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Varsha Gandhi - One of the best experts on this subject based on the ideXlab platform.

  • Preclinical and Clinical Evaluation of Forodesine in Pediatric and Adult B-Cell Acute Lymphoblastic Leukemia
    Clinical lymphoma myeloma & leukemia, 2013
    Co-Authors: Kumudha Balakrishnan, Shanta Bantia, Farhad Ravandi, Anna Franklin, Varsha Gandhi
    Abstract:

    Abstract Background The discovery that purine nucleoside phosphorylase (PNP) deficiency leads to T-cell lymphopenia was the basis for introducing PNP inhibitors for T-cell leukemias. Forodesine is an orally bioavailable PNP inhibitor with picomolar potency. Because T lymphoblasts and indolent chronic lymphocytic leukemia (CLL) B cells inherently elicit favorable pharmacokinetics to accumulate deoxyguanosine triphosphate (dGTP), Forodesine demonstrated promising activity in preclinical and clinical settings for patients with T-cell acute lymphoblastic leukemia (T-ALL) and B-cell CLL (B-CLL). However, the use of Forodesine in B-cell ALL (B-ALL) is unknown. Patients and Methods Leukemic blasts obtained from pediatric patients with de novo B-ALL (n = 10) were incubated with Forodesine and deoxyguanosine (dGuo), and the biological end points of apoptosis, intracellular dGTP accumulation, and inhibition of RNA and DNA synthesis were measured. Additionally, adult patients with B-ALL (n = 2) were intravenously infused with 80 mg/m 2 /d daily for 5 days. After therapy, clinical response, toxicity, laboratory biomarkers including PNP enzyme inhibition, and plasma Forodesine, dGuo, and intracellular dGTP levels were analyzed. Results Our in vitro investigations demonstrated that Forodesine treatment inhibited proliferation and induced modest apoptosis in de novo B-ALL lymphoblasts. There was time-dependent accumulation of dGTP and inhibition of RNA and DNA synthesis. During therapy, neither patient achieved a complete response (CR), but there was disease stabilization for several weeks in both patients. There was significant maintained inhibition of PNP enzyme in red blood cells, accumulation of Forodesine and dGuo in plasma, and intracellular dGTP accumulation in both patients. Conclusion Our preclinical and clinical investigations suggest that Forodesine has activity in B-ALL. However, it needs to be either infused with dGuo or combined with established chemotherapeutic agents based on mechanistic rationale.

  • Nucleoside Analogs in the Therapy of T-Cell Malignancies
    T-Cell Lymphomas, 2012
    Co-Authors: Varsha Gandhi, Pier Luigi Zinzani
    Abstract:

    Nucleoside analogs are a relatively novel group of cytotoxic agents that are highly immunosuppressive and have antineoplastic activity. These agents are characterized by cytotoxicity in both proliferating and nonproliferating cells though inhibition of DNA synthesis, inhibition of DNA repair, and induction of apoptosis. Pentostatin and gemcitabine are active against T-cell lymphomas. More recently, Forodesine and nelarabine have been investigated in T-cell malignancies.

  • Influence of bone marrow stromal microenvironment on Forodesine-induced responses in CLL primary cells
    Blood, 2010
    Co-Authors: Kumudha Balakrishnan, Mary Ayres, William G Wierda, Jan A. Burger, Maite P. Quiroga, Marina Henneberg, Varsha Gandhi
    Abstract:

    Forodesine, a purine nucleoside phosphorylase inhibitor, displays in vitro activity in chronic lymphocytic leukemia (CLL) cells in presence of dGuo, which is the basis for an ongoing clinical trial in patients with fludarabine-refractory CLL. Initial clinical data indicate Forodesine has significant activity on circulating CLL cells, but less activity in clearing CLL cells from tissues such as marrow. In tissue microenvironments, lymphocytes interact with accessory stromal cells that provide survival and drug-resistance signals, which may account for residual disease. Therefore, we investigated the impact of marrow stromal cells (MSCs) on Forodesine-induced response in CLL lymphocytes. We demonstrate that spontaneous and Forodesine-induced apoptosis of CLL cells was significantly inhibited by human and murine MSCs. Forodesine-promoted dGuo triphosphate (dGTP) accumulation and GTP and ATP depletion in CLL cells was inhibited by MSCs, providing a mechanism for resistance. Also, MSCs rescued CLL cells from Forodesine-induced RNA- and protein-synthesis inhibition and stabilized and increased Mcl-1 transcript and protein levels. Conversely, MSC viability was not affected by Forodesine and dGuo. Collectively, MSC-induced biochemical changes antagonized Forodesine-induced CLL cell apoptosis. This provides a biochemical mechanism for MSC-derived resistance to Forodesine and emphasizes the need to move toward combinations with agents that interfere with the microenvironment's protective role for improving current therapeutic efforts.

  • Forodesine: review of preclinical and clinical data.
    Future oncology (London England), 2010
    Co-Authors: Aref Al-kali, Varsha Gandhi, Mohamad Ayoubi, Michael J. Keating, Farhad Ravandi
    Abstract:

    Purine nucleoside phosphorylase (PNP) is an important catalytic enzyme in the purine salvage pathway; its deficiency is associated with T-cell lymphopenia and with humoral deficiency. This clinical observation led to the investigation of PNP inhibitors and their possible clinical application in the management of hematologic malignancies, notably those of T-cell lineage. Forodesine is the most potent of the PNP inhibitors. Its effect appears to be linked to increased 2´-deoxyguanosine levels in plasma, which in turn is converted to 2´-deoxyguanosine triphosphate in target cells and disrupts DNA synthesis. Several preclinical studies have shown Forodesine’s effect against lymphocytes in vitro and in vivo, and these findings have led to several Phase I/II studies in patients with lymphoid neoplasms. Early clinical trials show that Forodesine has promise as a single agent for the treatment of relapsed/refractory hematologic malignancies, and combination therapies might be warranted to improve clinical results.

  • abstract 5516 mechanisms of marrow stromal cells msc rescuing chronic lymphocytic leukemia cll lymphocytes from Forodesine induced apoptosis
    Cancer Research, 2009
    Co-Authors: Kumudha Balakrishnan, William G Wierda, Jan A. Burger, Maite P. Quiroga, Varsha Gandhi
    Abstract:

    AACR Annual Meeting-- Apr 18-22, 2009; Denver, CO Previously we demonstrated that Forodesine, a purine nucleoside phosphorylase inhibitor, in presence of deoxyguanosine (dGuo) showed efficacy during in vitro incubation of CLL lymphocytes by accumulating dGuo triphosphate (dGTP) without any effect on other deoxynucleotides. Intracellular increase in the level of dGTP in CLL-B cells was proportional to hall-mark features of apoptosis (Balakrishnan et al ; Blood 108:2392, 2006). Based on these encouraging data, a phase II clinical trial of Forodesine is initiated for fludarabine-refractory CLL patients. Because microenvironments, such as the bone marrow,provide niches in which leukemia cells may survivestandard chemotherapy, we investigated the role MSC on Forodesine-induced apoptosis, using 2 MSC lines (murine M2-10B4 and human NK-TERT). Both MSC lines decreased spontaneous apoptosis of CLL lymphocytes from 36% without stroma (48h, n=20) to 27% with M2-10B4 (n=15; p<0.05) and 9% with NK-TERT (n=7; p<0.05). Forodesine (2 µM) with 20 µM dGuo induced significant apoptosis in CLL lymphocytes with a median of 51% at 48h (n=20; p<0.05). Co-culture with both, M2-10B4 and NK-TERT significantly decreased Forodesine-induced apoptosis to 29% (n=15; p<0.05) or 15% (n=7; p<0.05), respectively. Similar survival advantages were observed at 24h of treatment. Median endogenous dGTP levels in CLL lymphocytes were 5 µM, which increased with Forodesine to a median of 21 µM (range: 10-31 µM). In co-cultures, both MSC lines slightly enhanced endogenous dGTP levels (median 7 µM with M2-10B4 and 12 µM with NK-TERT). With Forodesine, there was no further increase in dGTP levels in CLL lymphocytes co-cultured with MSC. Other dNTPs were not affected either by stromal cells or in the presence of Forodesine. Because dGTP perturbation was not fully associated with cell death, we tested additional mechanisms such as transcription inhibition. Although CLL lymphocytes are replicationally quiescent, they are transcriptionally active. Total RNA synthesis varied widely in CLL samples among patients but was inhibited by Forodesine in 3 of 4 samples (median 33%, range 21-41%; 48h). When CLL lymphocytes were co-cultured on stromal cells, RNA synthesis increased dramatically (2-46 folds with M2-10B4 and 2-6 folds with NK-TERT). CLL lymphocytes co-cultured on stromal cells when incubated with Forodesine, the RNA synthesis inhibition was partially recovered, but still not brought back to the levels in untreated cells. In conclusion, murine and human MSC rescue CLL lymphocytes from Forodesine-induced apoptosis. The mechanisms for this resistance seem to involve decrease in the intracellular accumulation of dGTP and reversal in the inhibition of RNA synthesis in CLL lymphocytes co-cultured with MSC. Therefore, combination strategies of Forodesine with agents that interfere with anti-apoptotic signals from the microenvironment might be beneficial. Citation Information: In: Proc Am Assoc Cancer Res; 2009 Apr 18-22; Denver, CO. Philadelphia (PA): AACR; 2009. Abstract nr 5516.

Kensei Tobinai - One of the best experts on this subject based on the ideXlab platform.

  • Forodesine in the treatment of relapsed/refractory peripheral T-cell lymphoma: an evidence-based review.
    OncoTargets and therapy, 2018
    Co-Authors: Shinichi Makita, Akiko Miyagi Maeshima, Dai Maruyama, Koji Izutsu, Kensei Tobinai
    Abstract:

    T-cell lymphoma is a rare hematologic malignancy with an incidence rate between 10% and 20% of that of non-Hodgkin lymphomas. Patients with peripheral T-cell lymphoma (PTCL) generally have a poor prognosis when treated with cyclophosphamide, doxorubicin, vincristine, and prednisolone (CHOP)/CHOP-like chemotherapy; once relapse occurs, it is mostly regarded as an incurable disease. To overcome the chemorefractoriness of PTCL, several novel agents have been developed. Since the first approval of pralatrexate, a dihydrofolate reductase inhibitor, for relapsed/refractory PTCL by the US Food and Drug Administration, several new agents, such as romidepsin (histone deacetylase inhibitor), brentuximab vedotin (antibody-drug conjugate targeting CD30), chidamide (histone deacetylase inhibitor), and mogamulizumab (anti-CC chemokine receptor 4 monoclonal antibody), have been approved as a therapeutic option for relapsed/refractory PTCL in several countries, including the US, Europe, China, and Japan. Forodesine is a novel, potent purine nucleoside phosphorylase inhibitor that is effective against T-cell malignancies. Although the clinical development of Forodesine was discontinued in the US and Europe, a multicenter Phase I/II study of oral Forodesine for relapsed PTCL was recently completed in Japan. The overall response rate was 24% (10 of 41 patients), which included four patients with complete response. In general, the toxicity of Forodesine is manageable. As the study met the primary end point, Forodesine was approved for the treatment of relapsed/refractory PTCL in Japan in March 2017, which was the first approval of Forodesine in the world. As Forodesine is an oral formulation, it is more convenient than other novel intravenous agents approved for PTCL. However, it is necessary to appropriately manage opportunistic infections and secondary lymphomas possibly associated with long-lasting lymphocytopenia caused by Forodesine. In this manuscript, we have summarized the currently available evidence for Forodesine and discussed the clinical implications for PTCL treatment.

  • Forodesine in the treatment of relapsed refractory peripheral t cell lymphoma an evidence based review
    OncoTargets and Therapy, 2018
    Co-Authors: Shinichi Makita, Akiko Miyagi Maeshima, Dai Maruyama, Koji Izutsu, Kensei Tobinai
    Abstract:

    T-cell lymphoma is a rare hematologic malignancy with an incidence rate between 10% and 20% of that of non-Hodgkin lymphomas. Patients with peripheral T-cell lymphoma (PTCL) generally have a poor prognosis when treated with cyclophosphamide, doxorubicin, vincristine, and prednisolone (CHOP)/CHOP-like chemotherapy; once relapse occurs, it is mostly regarded as an incurable disease. To overcome the chemorefractoriness of PTCL, several novel agents have been developed. Since the first approval of pralatrexate, a dihydrofolate reductase inhibitor, for relapsed/refractory PTCL by the US Food and Drug Administration, several new agents, such as romidepsin (histone deacetylase inhibitor), brentuximab vedotin (antibody-drug conjugate targeting CD30), chidamide (histone deacetylase inhibitor), and mogamulizumab (anti-CC chemokine receptor 4 monoclonal antibody), have been approved as a therapeutic option for relapsed/refractory PTCL in several countries, including the US, Europe, China, and Japan. Forodesine is a novel, potent purine nucleoside phosphorylase inhibitor that is effective against T-cell malignancies. Although the clinical development of Forodesine was discontinued in the US and Europe, a multicenter Phase I/II study of oral Forodesine for relapsed PTCL was recently completed in Japan. The overall response rate was 24% (10 of 41 patients), which included four patients with complete response. In general, the toxicity of Forodesine is manageable. As the study met the primary end point, Forodesine was approved for the treatment of relapsed/refractory PTCL in Japan in March 2017, which was the first approval of Forodesine in the world. As Forodesine is an oral formulation, it is more convenient than other novel intravenous agents approved for PTCL. However, it is necessary to appropriately manage opportunistic infections and secondary lymphomas possibly associated with long-lasting lymphocytopenia caused by Forodesine. In this manuscript, we have summarized the currently available evidence for Forodesine and discussed the clinical implications for PTCL treatment.

  • updated report of a phase i ii multicenter study of Forodesine a purine nucleoside phosphorylase inhibitor in japanese patients with relapsed peripheral t cell lymphoma
    Blood, 2017
    Co-Authors: Hirohiko Shibayama, Kensei Tobinai, Kunihiro Tsukasaki, Toshiki Uchida, Yoshinobu Maeda, Hirokazu Nagai, Mitsutoshi Kurosawa, Kiyohiko Hatake, Youko Suehiro, Kiyoshi Ando
    Abstract:

    Introduction: Forodesine, a potent purine nucleoside phosphorylase inhibitor, induces apoptosis mainly in T cells. A pivotal single-arm phase 1/2 study of Forodesine at high dose was conducted in patients with relapsed Peripheral T-Cell Lymphoma (PTCL) in Japan. The results of this study at the point of data cut off (Aug 2015) demonstrated that Forodesine has promising single-agent activity and led to its approval in Japan for the treatment of patients with relapsed/refractory PTCL. The overall response rate (ORR) among evaluable patients in the phase 2 part (n=41) was 22% (90% confidence interval [CI], 12-35%) (Tsukasaki, et al. ASCO 2016). Observation of all patients who continued administration at the time of data cut off was completed in February 2017. This is a report on the results using data up to the final observation of all patients. Methods: Eligible patients, who had relapsed PTCL, confirmed by central pathology review according to the WHO classification 2008, and without major organ dysfunction, received Forodesine 300 mg twice a day (BID) continuously. Tumor response was assessed with CT and PET by independent imaging review using IWC 2007 criteria. The study was conducted according to the Simon9s two-stage design. Although the primary endpoint of this study was the ORR until data cut off, ORR using all data was calculated in this report. Secondary endpoints included progression-free survival (PFS), overall survival (OS), and duration of response (DoR). Results: The ORR in 41 evaluable patients was 24% (10 of 41; 90% CI 13.9-37.9) including 4 CR (10%) and 6 PR (15%), the lower limit of the 90% CI exceeded the 10% threshold. Median PFS and OS were 1.9 and 15.6 months, respectively (Figure 1). The 2-year overall survival was 39%. The median time to response in 10 responders was 2.8 months (range 1.8-12.8) and the median DoR was 10.4 months (95% CI, 5.9-16.0). In safety evaluable patients (N=48), serious AEs (SAEs) after dosing were reported in 22 patients (46%). As a remarkable point, 5 patients [3 angioimmunoblastic T-cell lymphoma (AITL) and 2 PTCL-NOS] with B-NHL were reported. Four out of 5 patients were positive Epstein-Barr virus- encoded small RNA (EBER+) in the tumor cells (identified using in situ hybridization), and they were diagnosed as the Epstein-Barr virus positive diffuse large B-cell lymphoma (DLBCL). In these 4 patients, 3 patients developed B-NHL during the study period, more than 200 days after the start of administration of Forodesine. One patient developed B-NHL about one year after the end of administration of Forodesine. Other most common SAEs (≥2 patients) were pneumonia (4 patients), pyrexia (3 patients), Pneumocystis jirovecii pneumonia (2 patients) and anemia (2 patients). Conclusion:In the final data analysis, efficacy was confirmed against relapsed PTCL. The median DoR was 10.4 months (95% CI, 5.9-16.0 months), the responses to Forodesine were durable in some patients. Compared with other PTCL options that require intravenous infusion with frequent clinic visits, the oral formulation makes Forodesine easier to administer and, in turn, may be more convenient and less burdensome to patients. Forodesine would contribute as one of the reasonable options for the treatment of relapsed PTCL. Clinical Trial Information: NCT01776411. Disclosures Shibayama: Mundipharma K.K.: Honoraria, Research Funding; Novartis Pharma K.K.: Honoraria, Research Funding; Ono Pharmaceutical Co.,LTD.: Honoraria, Research Funding; Bristol-Meyer Squibb K.K.: Honoraria, Research Funding; Jansen Pharmaceutical K.K.: Honoraria; Fujimoto Pharmaceutical Co.: Honoraria, Research Funding; Takeda Pharmaceutical Co.,LTD.: Honoraria, Research Funding; Celgene K.K.: Honoraria, Research Funding. Tobinai: Janssen: Honoraria, Research Funding; Kyowa Hakko Kirin: Honoraria, Research Funding; Chugai: Honoraria, Research Funding; GlaxoSmithKline: Research Funding; Daiichi Sankyo Co., Ltd: Consultancy, Honoraria; AbbVie: Research Funding; HUYA Bioscience: Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Eisai: Honoraria, Research Funding; Servier: Research Funding; Mundipharma: Honoraria, Research Funding; Ono Pharmaceutical: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Zenyaku Kogyo: Honoraria. Tsukasaki: Takeda: Honoraria, Research Funding; Mundypharma: Research Funding; Zenyaku Kogyo: Honoraria; Celgene: Honoraria, Research Funding; HUYA: Honoraria; Kyowa-Kirin: Honoraria; DaiichiSankyo: Consultancy; Chugai/Roche: Honoraria. Uchida: Mundipharma K.K.: Research Funding; Janssen Pharmaceuticals: Honoraria. Maeda: Toko Pharmaceutical Industries: Other: Investigational drug is provided free of charge.. Nagai: Janssen, Mundipharma, Celgene, Bayer Yakuhin, AbbVie, Takeda, Chugai, Kyowa Hakko Kirin, Eisai: Research Funding; Chugai, Mundipharma, Eisai, Sanofi, Janssen: Honoraria. Hatake: AbbVie, Gilead, Celgene, Solasia, Pfizer, Bristol-Myers Squibb, Janssen, Ghugai: Research Funding; Mundipharma K.K.: Honoraria. Ando: MOCHIDA PHARMACEUTICAL: Other: Donation to institute; TOYAMA CHEMICAL: Other: Donation to institute; NOVARTIS: Other: Donation to institute; Meiji Seika Pharma: Other: Donation to institute; CHUGAI PHARMACEUTICAL: Other: Donation to institute; Sumitomo Dainippon Pharma: Other: Donation to institute; Eisai: Other: Donation to institute; Bristol-Myers Squibb: Other: Donation to institute; MSD: Other: Donation to institute; Kyowa Hakko Kirin: Other: Donation to institute; ALEXION: Other: Donation to institute; Takeda: Other: Donation to institute; Japan Blood Products Organization: Other: Donation to institute; Nippon Shinyaku: Other: Donation to institute; NIHON PHARMACEUTICAL: Other: Donation to institute; TAIHO: Other: Donation to institute; Asahi KASEI: Other: Donation to institute. Hidaka: Eisai: Honoraria; Chugai: Research Funding. Tamura: Mundipharma K.K.: Honoraria. Yamauchi: Bristol-Meyers Squibb, Chugai Pharma: Research Funding. Ueda: Mundipharma K.K.: Consultancy, Honoraria.

  • Phase 1/2 study of Forodesine in patients with relapsed peripheral t-cell lymphoma (PTCL).
    Journal of Clinical Oncology, 2016
    Co-Authors: Kunihiro Tsukasaki, Kensei Tobinai, Toshiki Uchida, Yoshinobu Maeda, Hirohiko Shibayama, Hirokazu Nagai, Mitsutoshi Kurosawa, Yasunobu Abe, Kiyohiko Hatake, Kiyoshi Ando
    Abstract:

    7542Background: Forodesine, a potent purine nucleoside phosphorylase inhibitor, induces apoptosis mainly in T cells. Forodesine at relatively low dose was feasible but the response rate was not suf...

  • phase i study of bcx1777 Forodesine in patients with relapsed or refractory peripheral t natural killer cell malignancies
    Cancer Science, 2012
    Co-Authors: Michinori Ogura, Dai Maruyama, Kunihiro Tsukasaki, Toshiki Uchida, Hirokazu Nagai, Jun Taguchi, Tatsuya Suzuki, Takashi Oyama, Tomomitsu Hotta, Kensei Tobinai
    Abstract:

    BCX1777 (Forodesine), a novel purine nucleoside phosphorylase inhibitor, induces apoptosis, mainly in T cells. To evaluate the safety, tolerability, and pharmacokinetics of BCX1777, we conducted a phase I study in patients with relapsed or refractory peripheral T/natural killer-cell malignancies. Eligible patients had relapsed or refractory peripheral T/natural killer-cell malignancies without any major organ dysfunction. BCX1777 was administered orally once daily (dose escalation: 100, 200, and 300 mg) until disease progression requiring new therapy or unacceptable adverse events occurred. A total of 13 patients were enrolled and treated in three dose cohorts (100 mg/day, five patients; 200 mg/day, three patients; 300 mg/day, five patients). Although none of the patients developed dose-limiting toxicities, further dose escalation was not performed based on data from overseas. Therefore, the maximum tolerated dose was not determined. Adverse events of grade 3 or greater (≥2 patients) included lymphopenia (62%), anemia (15%), leukopenia (8%), and pyrexia (8%). Plasma pharmacokinetics parameter of BCX1777 (area under the plasma concentration-time curve) at day 1 in each cohort was 1948 ± 884, 4608 ± 1030, and 4596 ± 939 ng•h/mL, respectively. Disease control was achieved in approximately half of patients. One patient with anaplastic large cell lymphoma, which was negative for anaplastic lymphoma kinase, achieved a complete response, and two patients with cutaneous T-cell lymphoma achieved partial responses. BCX1777 was well tolerated at doses up to 300 mg once daily and showed preliminary evidence of activity in relapsed or refractory peripheral T/natural killer-cell malignancies, warranting further investigation.

Tadeusz Robak - One of the best experts on this subject based on the ideXlab platform.

  • older and new purine nucleoside analogs for patients with acute leukemias
    Cancer Treatment Reviews, 2013
    Co-Authors: Pawel Robak, Tadeusz Robak
    Abstract:

    Purine nucleoside analogs (PNAs) compose a class of cytotoxic drugs that have played an important role in the treatment of hematological neoplasms, especially lymphoid and myeloid malignancies. All PNA drugs have a chemical structure similar to adenosine or guanosine, and they have similar mechanisms of action. They have many intracellular targets: they act as antimetabolites, competing with natural nucleosides during DNA or RNA synthesis, and as inhibitors of key cell enzymes. In contrast to other antineoplastic drugs, PNAs act cytotoxically, both in the mitotic and quiescent cell cycle phases. In the last few years, three PNAs have been approved for the treatment of lymphoid malignancies and other hematological disorders: 2-chlorodeoxyadenosine (2-CdA), fludarabine and pentostatin. 2-CdA and fludarabine are also active in the treatment of acute myeloid leukemia (AML). These drugs, in combination with cytarabine and other agents, are commonly used as salvage regimens in relapsed or refractory AML. Moreover, the addition of 2-CdA to the standard induction regimen is associated with an increased rate of complete remission and improved survival of adult patients with AML. More recently three novel PNAs have been synthesized and introduced into clinical trials: clofarabine, nelarabine and Forodesine. Clofarabine is the most promising PNA in current clinical trials in pediatric and adult patients with acute leukemias. Nelarabine is more cytotoxic in T-lineage than in B-lineage leukemias. Clofarabine and nelarabine have been approved for the treatment of refractory patients with acute lymphoblastic leukemia (ALL) and lymphoblastic lymphoma. Clofarabine is also an active drug in AML treatment when administered either alone or in combination regimens as front-line treatment and in relapsed or refractory patients. Unlike other PNA, Forodesine is not incorporated into DNA but displays a highly selective purine nucleoside phosphorylase inhibitory action. Forodesine is undergoing clinical trials for the treatment of T-cell malignancies, including T-cell ALL. This article summarizes recent achievements in the mechanism of action, pharmacological properties and clinical activity and toxicity of PNAs, as well as their emerging role in lymphoid and myeloid acute leukemias.

  • Purine nucleoside analogs in the treatment of rarer chronic lymphoid leukemias.
    Current pharmaceutical design, 2012
    Co-Authors: Tadeusz Robak, Pawel Robak
    Abstract:

    Purine nucleoside analogues (PNA) are the cytotoxic agents highly active in the treatment of indolent lymphoid malignancies. These drugs have chemical structure similar to adenosine or deoxyadenosine. PNAs are characterized by a similar mechanism of cytotoxicity both in proliferating and quiescent cells, such as inhibition of DNA synthesis, inhibition of DNA repair and accumulation of DNA strand breaks. In addition, PNAs induce apoptosis which is the end-point of their action. Older PNAs, pentostatin (DCF; 2'- deoxycoformycin), cladribine (2-CdA; 2-chloro-2'-deoxyadenosine) and fludarabine (2-fluoro-9-(-D-arabinosyl)-adenine) were approved by Food and Drug Administration (FDA) for the treatment of hematological malignancies. In addition three novel PNAs: clofarabine (CAFdA), nelarabine (ara-G) and Forodesine (immucillin H, BCX-1777) have been synthesized and introduced into preclinical studies and clinical trials. This review summarizes current knowledge on the mechanism of action and pharmacokinetic properties of older and new PNAs. Clinical activity and toxicity of PNAs, especially in hairy cell leukemia (HCL), hairy cell leukemia variant (HCL-V), prolymphocytic leukemia (PLL) and other rarer chronic lymphoid leukemias, are also presented. 2-CdA and DCF, introduced in the 1980s, changed radically the treatment modality, inducing complete and durable responses in the majority of patients with HCL. In contrast, the results of the treatment of HCL-V with PNA are rather poor. There are also several reports indicating activity of PNAs in PLL and large granular lymphocyte leukemia. Clofarabine, nelarabine and Forodesine need further investigation in rarer lymphid leukemias, to better define their status in the treatment of these disorders.

  • New nucleoside analogs for patients with hematological malignancies.
    Expert opinion on investigational drugs, 2011
    Co-Authors: Tadeusz Robak
    Abstract:

    Introduction: In the last few years, several new purine and pyrimidine nucleoside analogs have been synthesized and made available for both preclinical studies and clinical trials. Areas covered: This article summarizes recent achievements in the mechanism of action, pharmacological properties and clinical activity and toxicity as well as the emerging role of newer purine and pyrimidine nucleoside analogs potentially active in lymphoid and myeloid malignancies. A literature review was conducted from the MEDLINE database PubMed for articles in English. Publications from 2000 to October 2010 were scrutinized. The search terms used were clofarabine, nelarabine, Forodesine, 8-chloroadenosine, LMP-420, azacitidine, decitabine, sapacitabine, troxacitabine, thiarabine and zebularine in conjunction with hematologic malignancies, leukemia and lymphoma. Conference proceedings from the previous 5 years of the American Society of Hematology, European Hematology Association, and American Society of Clinical Oncology w...

  • Novel Systemic Drugs for Cutaneous T-Cell Lymphoma
    Recent patents on anti-cancer drug discovery, 2011
    Co-Authors: Ewa Lech-marańda, Ewa Robak, Tadeusz Robak
    Abstract:

    For the last few years new therapeutic options for primary cutaneous T-cell lymphoma (CTCL) have been recently introduced into clinical trials, particularly for patients with advanced stage and refractory disease. Systemic treatment uses biological response modifiers, such as fusion molecules, rexinoids, interferons as well as monoclonal antiobodies, and new antiproliferative drugs, such as histone deacetylase inhibitors, proteasome inhibitors or Forodesine. This review focuses on recent advances in the development of systemic agents for CTCL including both novel patented compounds and novel therapeutic protocol of intervention.

  • current status of older and new purine nucleoside analogues in the treatment of lymphoproliferative diseases
    Molecules, 2009
    Co-Authors: Tadeusz Robak, Anna Korycka, Ewa Lechmaranda, Pawel Robak
    Abstract:

    For the past few years more and more new cytotoxic agents active in the treatment of hematological malignancies have been synthesized and become available for either in vitro studies or clinical trials. Among them the class of antineoplastic drugs belonging to the purine nucleoside analogues group (PNAs) plays an important role. Three of them: pentostatin (DCF), cladribine (2-CdA) and fludarabine (FA) were approved by Food and Drug Administration (FDA) for the treatment of hematological malignancies. Recently three novel PNAs: clofarabine (CAFdA), nelarabine (ara-G) and Forodesine (immucillin H, BCX-1777) have been synthesized and introduced into preclinical studies and clinical trials. These agents seem to be useful mainly for the treatment of human T-cell proliferative disorders and they are currently undergoing clinical trials in lymphoid malignancies. However, there are also several studies suggesting the role of these drugs in B-cell malignancies. This review will summarize current knowledge concerning the mechanism of action, pharmacologic properties, clinical activity and toxicity of PNAs accepted for use in clinical practice, as well as new agents available for clinical trials.

Kumudha Balakrishnan - One of the best experts on this subject based on the ideXlab platform.

  • Preclinical and Clinical Evaluation of Forodesine in Pediatric and Adult B-Cell Acute Lymphoblastic Leukemia
    Clinical lymphoma myeloma & leukemia, 2013
    Co-Authors: Kumudha Balakrishnan, Shanta Bantia, Farhad Ravandi, Anna Franklin, Varsha Gandhi
    Abstract:

    Abstract Background The discovery that purine nucleoside phosphorylase (PNP) deficiency leads to T-cell lymphopenia was the basis for introducing PNP inhibitors for T-cell leukemias. Forodesine is an orally bioavailable PNP inhibitor with picomolar potency. Because T lymphoblasts and indolent chronic lymphocytic leukemia (CLL) B cells inherently elicit favorable pharmacokinetics to accumulate deoxyguanosine triphosphate (dGTP), Forodesine demonstrated promising activity in preclinical and clinical settings for patients with T-cell acute lymphoblastic leukemia (T-ALL) and B-cell CLL (B-CLL). However, the use of Forodesine in B-cell ALL (B-ALL) is unknown. Patients and Methods Leukemic blasts obtained from pediatric patients with de novo B-ALL (n = 10) were incubated with Forodesine and deoxyguanosine (dGuo), and the biological end points of apoptosis, intracellular dGTP accumulation, and inhibition of RNA and DNA synthesis were measured. Additionally, adult patients with B-ALL (n = 2) were intravenously infused with 80 mg/m 2 /d daily for 5 days. After therapy, clinical response, toxicity, laboratory biomarkers including PNP enzyme inhibition, and plasma Forodesine, dGuo, and intracellular dGTP levels were analyzed. Results Our in vitro investigations demonstrated that Forodesine treatment inhibited proliferation and induced modest apoptosis in de novo B-ALL lymphoblasts. There was time-dependent accumulation of dGTP and inhibition of RNA and DNA synthesis. During therapy, neither patient achieved a complete response (CR), but there was disease stabilization for several weeks in both patients. There was significant maintained inhibition of PNP enzyme in red blood cells, accumulation of Forodesine and dGuo in plasma, and intracellular dGTP accumulation in both patients. Conclusion Our preclinical and clinical investigations suggest that Forodesine has activity in B-ALL. However, it needs to be either infused with dGuo or combined with established chemotherapeutic agents based on mechanistic rationale.

  • Influence of bone marrow stromal microenvironment on Forodesine-induced responses in CLL primary cells
    Blood, 2010
    Co-Authors: Kumudha Balakrishnan, Mary Ayres, William G Wierda, Jan A. Burger, Maite P. Quiroga, Marina Henneberg, Varsha Gandhi
    Abstract:

    Forodesine, a purine nucleoside phosphorylase inhibitor, displays in vitro activity in chronic lymphocytic leukemia (CLL) cells in presence of dGuo, which is the basis for an ongoing clinical trial in patients with fludarabine-refractory CLL. Initial clinical data indicate Forodesine has significant activity on circulating CLL cells, but less activity in clearing CLL cells from tissues such as marrow. In tissue microenvironments, lymphocytes interact with accessory stromal cells that provide survival and drug-resistance signals, which may account for residual disease. Therefore, we investigated the impact of marrow stromal cells (MSCs) on Forodesine-induced response in CLL lymphocytes. We demonstrate that spontaneous and Forodesine-induced apoptosis of CLL cells was significantly inhibited by human and murine MSCs. Forodesine-promoted dGuo triphosphate (dGTP) accumulation and GTP and ATP depletion in CLL cells was inhibited by MSCs, providing a mechanism for resistance. Also, MSCs rescued CLL cells from Forodesine-induced RNA- and protein-synthesis inhibition and stabilized and increased Mcl-1 transcript and protein levels. Conversely, MSC viability was not affected by Forodesine and dGuo. Collectively, MSC-induced biochemical changes antagonized Forodesine-induced CLL cell apoptosis. This provides a biochemical mechanism for MSC-derived resistance to Forodesine and emphasizes the need to move toward combinations with agents that interfere with the microenvironment's protective role for improving current therapeutic efforts.

  • Phase 2 and pharmacodynamic study of oral Forodesine in patients with advanced, fludarabine-treated chronic lymphocytic leukemia.
    Blood, 2010
    Co-Authors: Kumudha Balakrishnan, Shanta Bantia, Michael J. Keating, Dushyant Verma, Susan O'brien, Susan Bickel, J.m. Kilpatrick, Yuling Chen, Brenita F. Tyler, Hagop M Kantarjian
    Abstract:

    Forodesine is a new and potent purine nucleoside phosphorylase (PNP) inhibitor. Patients with chronic lymphocytic leukemia (CLL) with primary resistance to fludarabine-based therapy or with progressive disease were eligible for oral Forodesine (200 mg/d) for up to 24 weeks. Eight patients with median lymphocyte count of 35.9 × 109/L and median serum β2 microglobulin level of 6.45 mg/L were treated. Six had Rai stage III to IV and were previously heavily treated (median prior therapy = 5). Two had transient decrease in lymphocyte count to normal, whereas in 5, disease progressed. Adverse events were mild. Steady-state level of Forodesine ranged from 200 to 1300nM and did not reach desired 2μM level. PNP inhibition ranged from 57% to 89% and steady-state 2′-deoxyguanosine (dGuo) concentration median was 1.8μM. Intracellular deoxyguanosine triphosphate (dGTP) increase was very modest, from median of 6μM to 10μM. Compared with in vivo, in vitro incubations of CLL lymphocytes with 10 or 20μM dGuo and Forodesine (2μM) resulted in accumulation of higher levels of dGTP (40-250μM) which resulted in increase in apoptosis. Forodesine has biologic activity in CLL; pharmacodynamic parameters suggest that an alternate dosing schedule and/or higher doses to achieve greater intracellular dGTP may be beneficial in this patient population. This study is registered at www.clinicaltrials.gov as #NCT00289549.

  • Phase II, Single Center Study of Oral Forodesine in Patients with Advanced, Fludarabine-Treated Chronic Lymphocytic Leukemia (CLL).
    Blood, 2009
    Co-Authors: Dushyant Verma, William G Wierda, Stefan Faderl, Kumudha Balakrishnan, Susan O'brien, Deborah A. Thomas, Alessandra Ferrajoli, Amit Verma, Susan Bickel, Shanta Bantia
    Abstract:

    Abstract 2369 Poster Board II-346 Background: The prognosis of fludarabine-refractory patients is poor and the current salvage regimens produce low CR rates and are unlikely to improve long-term survival in this patient population. Forodesine, an analog inhibitor of the enzyme purine nucleoside phosphorylase (PNP), leads to rise in plasma dGuo levels followed by accumulation of dGTP in T-cells,that results in DNA breakdown and cell apoptosis. Forodesine has exhibited promising clinical activity in T cell leukemia with complete inhibition of PNP during therapy (Gandhi et al, Blood 106:4253, 2005). Previous in-vitro studies conducted by our group demonstrated that Forodesine induces caspase dependent cell death in primary CLL cells by accumulating high intracellular dGTP in CLL cells (Balakrishnan et al, Blood 108:2392, 2006). This provided the rationale to test Forodesine in B-CLL. Aims: i) to investigate the efficacy (CR + PR) of Forodesine in treating patients with advanced, fludarabine-treated CLL, ii) to evaluate the toxicity, duration of response, disease-free survival and overall survival associated with treatment with Forodesine, and iii) to correlate PK/PD data of Forodesine in CLL with its clinical activity. Methods: Patients with primary resistance to fludarabine-based therapy (no CR or PR) or with progressive disease after response to prior fludarabine based regimen were eligible. The Forodesine dose was 200 mg oral once daily, administered continuously up to a maximum of 24 weeks. Blood samples were collected on days 1-5 and day 28 and pharmacokinetic and pharmacodynamic parameters were determined. Ex vivo incubation with Forodesine and dGuo were also performed in CLL lymphocytes to compare the treatment effects in vivo and ex vivo investigations. Results: 8 patients were treated, the median age was 62 years (range 51-68), 7 males, median absolute lymphocyte count 35.85 (range 1.4-156.66) × 10 9 /L, median serum beta 2 microglobulin level was 6.45 (range 3.6-16.3) mg/L. Six patients had Rai stage III-IV disease, the, median number of prior therapy was 5 (range 1-10), 5 patients were fludarabine refractory, 5 were ZAP-70 positive. Seven patients are evaluable for response and toxicity. Two patients had a transient decrease in their absolute lymphocyte count to normal level after the first 4 weeks, but it was short lasting. In the other 5 patients, the WBC counts increased progressively and in 3 patients there was also progression in lymphadenopathies. The toxicities observed were mild and included fatigue, bronchitis, diarrhea and low grade fever. Myelosuppression was transient and included neutropenia thrombocytopenia in 3 patients. One patient had pneumonia. The steady-state level of Forodesine, measured on day 2, 3, 4, and 5, ranged between 200-1300 nM (n=8). At these concentrations, PNP inhibition in circulating RBCs, ranged between 57 and 89% (n=8). With this extent of PNP inhibition, steady-state dGuo concentration was a median 1.8 μM (range, 0.56 – 4.4 μM, n=8). The starting level of intracellular dGTP was a median 5 μM (range, 0.9 - 7.8 μM, n = 7) which increased to a median 12.5 μM (range 1.9 - 65 μM, n = 7). The circulating lymphocytes did not show annexin positivity above 10% during the first five days of treatment. To determine if CLL lymphocytes accumulate dGTP at high dGuo (10 and 20 μM) levels, we performed ex vivo incubations. Compared to in vivo , higher levels of dGTP were achieved ex vivo with a 10-50% increase in apoptosis. Conclusion: Oral Forodesine showed activity with decrease in peripheral lymphocyte counts in 2 of 7 evaluable patients. However, all patients ultimately progressed while on treatment. Side effects were mild. The ex vivo biologic data and in vivo pharmacodynamic and clinical data suggest that Forodesine has biological activity, and that alternative dosing schedules should be explored in future CLL trials. Disclosures: Off Label Use: Forodesine is not approved by FDA for treatment of CLL. Bantia: BioCryst: Employment. Gandhi: Mundipharma: Honoraria, Research Funding; Biocryst: Honoraria, Research Funding. Ravandi: Biocryst: Research Funding.

  • abstract 5516 mechanisms of marrow stromal cells msc rescuing chronic lymphocytic leukemia cll lymphocytes from Forodesine induced apoptosis
    Cancer Research, 2009
    Co-Authors: Kumudha Balakrishnan, William G Wierda, Jan A. Burger, Maite P. Quiroga, Varsha Gandhi
    Abstract:

    AACR Annual Meeting-- Apr 18-22, 2009; Denver, CO Previously we demonstrated that Forodesine, a purine nucleoside phosphorylase inhibitor, in presence of deoxyguanosine (dGuo) showed efficacy during in vitro incubation of CLL lymphocytes by accumulating dGuo triphosphate (dGTP) without any effect on other deoxynucleotides. Intracellular increase in the level of dGTP in CLL-B cells was proportional to hall-mark features of apoptosis (Balakrishnan et al ; Blood 108:2392, 2006). Based on these encouraging data, a phase II clinical trial of Forodesine is initiated for fludarabine-refractory CLL patients. Because microenvironments, such as the bone marrow,provide niches in which leukemia cells may survivestandard chemotherapy, we investigated the role MSC on Forodesine-induced apoptosis, using 2 MSC lines (murine M2-10B4 and human NK-TERT). Both MSC lines decreased spontaneous apoptosis of CLL lymphocytes from 36% without stroma (48h, n=20) to 27% with M2-10B4 (n=15; p<0.05) and 9% with NK-TERT (n=7; p<0.05). Forodesine (2 µM) with 20 µM dGuo induced significant apoptosis in CLL lymphocytes with a median of 51% at 48h (n=20; p<0.05). Co-culture with both, M2-10B4 and NK-TERT significantly decreased Forodesine-induced apoptosis to 29% (n=15; p<0.05) or 15% (n=7; p<0.05), respectively. Similar survival advantages were observed at 24h of treatment. Median endogenous dGTP levels in CLL lymphocytes were 5 µM, which increased with Forodesine to a median of 21 µM (range: 10-31 µM). In co-cultures, both MSC lines slightly enhanced endogenous dGTP levels (median 7 µM with M2-10B4 and 12 µM with NK-TERT). With Forodesine, there was no further increase in dGTP levels in CLL lymphocytes co-cultured with MSC. Other dNTPs were not affected either by stromal cells or in the presence of Forodesine. Because dGTP perturbation was not fully associated with cell death, we tested additional mechanisms such as transcription inhibition. Although CLL lymphocytes are replicationally quiescent, they are transcriptionally active. Total RNA synthesis varied widely in CLL samples among patients but was inhibited by Forodesine in 3 of 4 samples (median 33%, range 21-41%; 48h). When CLL lymphocytes were co-cultured on stromal cells, RNA synthesis increased dramatically (2-46 folds with M2-10B4 and 2-6 folds with NK-TERT). CLL lymphocytes co-cultured on stromal cells when incubated with Forodesine, the RNA synthesis inhibition was partially recovered, but still not brought back to the levels in untreated cells. In conclusion, murine and human MSC rescue CLL lymphocytes from Forodesine-induced apoptosis. The mechanisms for this resistance seem to involve decrease in the intracellular accumulation of dGTP and reversal in the inhibition of RNA synthesis in CLL lymphocytes co-cultured with MSC. Therefore, combination strategies of Forodesine with agents that interfere with anti-apoptotic signals from the microenvironment might be beneficial. Citation Information: In: Proc Am Assoc Cancer Res; 2009 Apr 18-22; Denver, CO. Philadelphia (PA): AACR; 2009. Abstract nr 5516.

Shanta Bantia - One of the best experts on this subject based on the ideXlab platform.

  • Preclinical and Clinical Evaluation of Forodesine in Pediatric and Adult B-Cell Acute Lymphoblastic Leukemia
    Clinical lymphoma myeloma & leukemia, 2013
    Co-Authors: Kumudha Balakrishnan, Shanta Bantia, Farhad Ravandi, Anna Franklin, Varsha Gandhi
    Abstract:

    Abstract Background The discovery that purine nucleoside phosphorylase (PNP) deficiency leads to T-cell lymphopenia was the basis for introducing PNP inhibitors for T-cell leukemias. Forodesine is an orally bioavailable PNP inhibitor with picomolar potency. Because T lymphoblasts and indolent chronic lymphocytic leukemia (CLL) B cells inherently elicit favorable pharmacokinetics to accumulate deoxyguanosine triphosphate (dGTP), Forodesine demonstrated promising activity in preclinical and clinical settings for patients with T-cell acute lymphoblastic leukemia (T-ALL) and B-cell CLL (B-CLL). However, the use of Forodesine in B-cell ALL (B-ALL) is unknown. Patients and Methods Leukemic blasts obtained from pediatric patients with de novo B-ALL (n = 10) were incubated with Forodesine and deoxyguanosine (dGuo), and the biological end points of apoptosis, intracellular dGTP accumulation, and inhibition of RNA and DNA synthesis were measured. Additionally, adult patients with B-ALL (n = 2) were intravenously infused with 80 mg/m 2 /d daily for 5 days. After therapy, clinical response, toxicity, laboratory biomarkers including PNP enzyme inhibition, and plasma Forodesine, dGuo, and intracellular dGTP levels were analyzed. Results Our in vitro investigations demonstrated that Forodesine treatment inhibited proliferation and induced modest apoptosis in de novo B-ALL lymphoblasts. There was time-dependent accumulation of dGTP and inhibition of RNA and DNA synthesis. During therapy, neither patient achieved a complete response (CR), but there was disease stabilization for several weeks in both patients. There was significant maintained inhibition of PNP enzyme in red blood cells, accumulation of Forodesine and dGuo in plasma, and intracellular dGTP accumulation in both patients. Conclusion Our preclinical and clinical investigations suggest that Forodesine has activity in B-ALL. However, it needs to be either infused with dGuo or combined with established chemotherapeutic agents based on mechanistic rationale.

  • In vitro efficacy of Forodesine and nelarabine (ara-G) in pediatric leukemia
    Blood, 2011
    Co-Authors: Irene Homminga, Shanta Bantia, Chantal Y. Manz, Cynthia Parker, Rob Pieters, C. Michel Zwaan, Willem K. Smits, Fiona Higginbotham, Jules P.p. Meijerink
    Abstract:

    Forodesine and nelarabine (the pro-drug of ara-G) are 2 nucleoside analogues with promising anti-leukemic activity. To better understand which pediatric patients might benefit from Forodesine or nelarabine (ara-G) therapy, we investigated the in vitro sensitivity to these drugs in 96 diagnostic pediatric leukemia patient samples and the mRNA expression levels of different enzymes involved in nucleoside metabolism. Forodesine and ara-G cytotoxicities were higher in T-cell acute lymphoblastic leukemia (T-ALL) samples than in B-cell precursor (BCP)–ALL and acute myeloid leukemia (AML) samples. Resistance to Forodesine did not preclude ara-G sensitivity and vice versa, indicating that both drugs rely on different resistance mechanisms. Differences in sensitivity could be partly explained by significantly higher accumulation of intracellular dGTP in Forodesine-sensitive samples compared with resistant samples, and higher mRNA levels of dGK but not dCK . The mRNA levels of the transporters ENT1 and ENT2 were higher in ara-G–sensitive than –resistant samples. We conclude that especially T-ALL, but also BCP-ALL, pediatric patients may benefit from Forodesine or nelarabine (ara-G) treatment.

  • Phase 2 and pharmacodynamic study of oral Forodesine in patients with advanced, fludarabine-treated chronic lymphocytic leukemia.
    Blood, 2010
    Co-Authors: Kumudha Balakrishnan, Shanta Bantia, Michael J. Keating, Dushyant Verma, Susan O'brien, Susan Bickel, J.m. Kilpatrick, Yuling Chen, Brenita F. Tyler, Hagop M Kantarjian
    Abstract:

    Forodesine is a new and potent purine nucleoside phosphorylase (PNP) inhibitor. Patients with chronic lymphocytic leukemia (CLL) with primary resistance to fludarabine-based therapy or with progressive disease were eligible for oral Forodesine (200 mg/d) for up to 24 weeks. Eight patients with median lymphocyte count of 35.9 × 109/L and median serum β2 microglobulin level of 6.45 mg/L were treated. Six had Rai stage III to IV and were previously heavily treated (median prior therapy = 5). Two had transient decrease in lymphocyte count to normal, whereas in 5, disease progressed. Adverse events were mild. Steady-state level of Forodesine ranged from 200 to 1300nM and did not reach desired 2μM level. PNP inhibition ranged from 57% to 89% and steady-state 2′-deoxyguanosine (dGuo) concentration median was 1.8μM. Intracellular deoxyguanosine triphosphate (dGTP) increase was very modest, from median of 6μM to 10μM. Compared with in vivo, in vitro incubations of CLL lymphocytes with 10 or 20μM dGuo and Forodesine (2μM) resulted in accumulation of higher levels of dGTP (40-250μM) which resulted in increase in apoptosis. Forodesine has biologic activity in CLL; pharmacodynamic parameters suggest that an alternate dosing schedule and/or higher doses to achieve greater intracellular dGTP may be beneficial in this patient population. This study is registered at www.clinicaltrials.gov as #NCT00289549.

  • In-Vitro Efficacy of the Deoxyguanoside Analogs Forodesine (BCX-1777) and ARA-G in Pediatric Acute Lymphoblastic Leukemia.
    Blood, 2009
    Co-Authors: Irene Homminga, Shanta Bantia, Chantal Y. Manz, Wilco Smits, Rob Pieters, Michel C. Zwaan, Amel Seghouani, Jules P.p. Meijerink
    Abstract:

    Abstract Abstract 2038 Poster Board II-15 Purine nucleoside phosphorylase (PNP) deficiency in humans is associated with elevated deoxyguanosine (dGuo) plasma levels. DGuo is converted into dGTP inducing apoptosis in T-cells and this provides the rationale for the development of deoxyguanosine analogues as a potential treatment option for T-cell malignancies. Forodesine (BCX-1777; BioCryst-Mundipharma) is an efficient blocker of PNP activity, thereby boosting the conversion of dGuo into dGTP and raising intracellular dGTP levels. AraG (9-b-D-arabinofuranosyl-guanine) is a compound that is resistant to PNP-mediated degradation that is efficiently converted into AraGTP. AraGTP becomes incorporated in the DNA, blocking DNA synthesis and promoting apoptosis. In a phase II clinical trial, the AraG prodrug Nelarabine enforced a complete remission rate of 55% for pediatric T-ALL patients at 1st relapse. (Berg, JCO 2005). Clinical data of Forodesine treatment in pediatric ALL patients are not yet available. As tested on primary pediatric acute lymphoblastic leukemia (ALL) patient samples (4 T-ALL, 2 BCP-ALL), 1μM of Forodesine is sufficient to completely block PNP and abolish rapid dGuo degradation resulting in a median 7.9 (range 0.5-378) fold raise of intracellular dGTP levels. Accumulation of dGTP is comparable for T-ALL (n=31) and BCP-ALL (n=11) patient samples. This reflects equal intrinsic ability of salvage nucleotide synthesis for both T-ALL and BCP-ALL cells. Cytotoxic effect of Forodesine was tested on primary leukemia cells from newly diagnosed pediatric ALL patients in-vitro by incubating cells with Forodesine (1μM) in the presence of increasing concentrations of dGuo (0.001-50μM). In accordance with selective T-cell toxicity, T-ALL cells were more sensitive to Forodesine/dGuo treatment (median T-ALL LC50 value: 1.1μM dGuo/1μM Forodesine, n=27, p=0.001) compared to BCP-ALL cells, which had a median LC50 value of 8.8μM dGuo/1μM Forodesine (n=30). All patients that responded demonstrated dGTP accumulation (1.5-222.1 fold), although the raise of dGTP levels did not correlate with Forodesine/dGuo toxicity (r2= 0.10, p=0.22). Studying in-vitro responsiveness to AraG, T-ALL cells were more sensitive compared to BCP-ALL cells (p=0.0002) with a median AraG LC50 value of 20.5μM for T-ALL samples (n=24) versus 48.3μM for BCP-ALL samples (n=20). Remarkably, TELAML1 positive BCP-ALL cases were insensitive to AraG treatment (median LC50 value >50μM, n=9). No correlation was identified between in-vitro Forodesine/dGuo and AraG cytotoxicities (r2=0.05, p=0.29). Most patient samples that displayed AraG resistance still responded to Forodesine/dGuo treatment. This may be explained by the fact that the uptake of both drugs may be facilitated by different transporters. Using RQ-PCR we could demonstrate that AraG toxicity, in contrast to Forodesine, was significantly associated with ENT1 (equilibrative nucleoside transporter 1) expression levels (p=0.008), which was previously identified as strong predictor for AraC cytotoxicity in pediatric ALL (Stam RW. et al., Blood 2003). AraG cytotoxicity strongly correlated with AraC cytotoxicity (r2=0.71, p<0.0001). We found no significant correlation between Forodesine sensitivity and the expression levels of other nucleoside transporters (CNT1, CNT2, CNT3, ENT2), kinases (dCK, dGK), nucleotidases (NT5C1A, NT5C2, PNI) or other enzymes that are involved in dGuo metabolism (PNP, RRM1, RRM2). In conclusion, T-ALL cells are more sensitive to Forodesine/dGuo treatment in-vitro than BCP-ALL cells that have nearly 8 fold higher dGuo LC50 values. Resistance to AraG treatment does not preclude responsiveness to Forodesine treatment and vice versa, indicating that Forodesine and AraG rely on different cellular mechanisms for cytotoxicity, possibly involving differences in dependence on the nucleoside transporter ENT1. Disclosures: No relevant conflicts of interest to declare.

  • Phase II, Single Center Study of Oral Forodesine in Patients with Advanced, Fludarabine-Treated Chronic Lymphocytic Leukemia (CLL).
    Blood, 2009
    Co-Authors: Dushyant Verma, William G Wierda, Stefan Faderl, Kumudha Balakrishnan, Susan O'brien, Deborah A. Thomas, Alessandra Ferrajoli, Amit Verma, Susan Bickel, Shanta Bantia
    Abstract:

    Abstract 2369 Poster Board II-346 Background: The prognosis of fludarabine-refractory patients is poor and the current salvage regimens produce low CR rates and are unlikely to improve long-term survival in this patient population. Forodesine, an analog inhibitor of the enzyme purine nucleoside phosphorylase (PNP), leads to rise in plasma dGuo levels followed by accumulation of dGTP in T-cells,that results in DNA breakdown and cell apoptosis. Forodesine has exhibited promising clinical activity in T cell leukemia with complete inhibition of PNP during therapy (Gandhi et al, Blood 106:4253, 2005). Previous in-vitro studies conducted by our group demonstrated that Forodesine induces caspase dependent cell death in primary CLL cells by accumulating high intracellular dGTP in CLL cells (Balakrishnan et al, Blood 108:2392, 2006). This provided the rationale to test Forodesine in B-CLL. Aims: i) to investigate the efficacy (CR + PR) of Forodesine in treating patients with advanced, fludarabine-treated CLL, ii) to evaluate the toxicity, duration of response, disease-free survival and overall survival associated with treatment with Forodesine, and iii) to correlate PK/PD data of Forodesine in CLL with its clinical activity. Methods: Patients with primary resistance to fludarabine-based therapy (no CR or PR) or with progressive disease after response to prior fludarabine based regimen were eligible. The Forodesine dose was 200 mg oral once daily, administered continuously up to a maximum of 24 weeks. Blood samples were collected on days 1-5 and day 28 and pharmacokinetic and pharmacodynamic parameters were determined. Ex vivo incubation with Forodesine and dGuo were also performed in CLL lymphocytes to compare the treatment effects in vivo and ex vivo investigations. Results: 8 patients were treated, the median age was 62 years (range 51-68), 7 males, median absolute lymphocyte count 35.85 (range 1.4-156.66) × 10 9 /L, median serum beta 2 microglobulin level was 6.45 (range 3.6-16.3) mg/L. Six patients had Rai stage III-IV disease, the, median number of prior therapy was 5 (range 1-10), 5 patients were fludarabine refractory, 5 were ZAP-70 positive. Seven patients are evaluable for response and toxicity. Two patients had a transient decrease in their absolute lymphocyte count to normal level after the first 4 weeks, but it was short lasting. In the other 5 patients, the WBC counts increased progressively and in 3 patients there was also progression in lymphadenopathies. The toxicities observed were mild and included fatigue, bronchitis, diarrhea and low grade fever. Myelosuppression was transient and included neutropenia thrombocytopenia in 3 patients. One patient had pneumonia. The steady-state level of Forodesine, measured on day 2, 3, 4, and 5, ranged between 200-1300 nM (n=8). At these concentrations, PNP inhibition in circulating RBCs, ranged between 57 and 89% (n=8). With this extent of PNP inhibition, steady-state dGuo concentration was a median 1.8 μM (range, 0.56 – 4.4 μM, n=8). The starting level of intracellular dGTP was a median 5 μM (range, 0.9 - 7.8 μM, n = 7) which increased to a median 12.5 μM (range 1.9 - 65 μM, n = 7). The circulating lymphocytes did not show annexin positivity above 10% during the first five days of treatment. To determine if CLL lymphocytes accumulate dGTP at high dGuo (10 and 20 μM) levels, we performed ex vivo incubations. Compared to in vivo , higher levels of dGTP were achieved ex vivo with a 10-50% increase in apoptosis. Conclusion: Oral Forodesine showed activity with decrease in peripheral lymphocyte counts in 2 of 7 evaluable patients. However, all patients ultimately progressed while on treatment. Side effects were mild. The ex vivo biologic data and in vivo pharmacodynamic and clinical data suggest that Forodesine has biological activity, and that alternative dosing schedules should be explored in future CLL trials. Disclosures: Off Label Use: Forodesine is not approved by FDA for treatment of CLL. Bantia: BioCryst: Employment. Gandhi: Mundipharma: Honoraria, Research Funding; Biocryst: Honoraria, Research Funding. Ravandi: Biocryst: Research Funding.