BACKGROUND Blinatumomab, a bispecific monoclonal antibody construct that enables CD3-positive T cells to recognize and eliminate CD19-positive acute lymphoblastic leukemia (ALL) blasts, was approved for use in patients with relapsed or refractory B-cell precursor ALL on the basis of single-group trials that showed efficacy and manageable toxic effects. METHODS In this multi-institutional phase 3 trial, we randomly assigned adults with heavily pretreated B-cell precursor ALL, in a 2:1 ratio, to receive either blinatumomab or standard-of-care chemotherapy. The primary end point was overall survival. RESULTS Of the 405 patients who were randomly assigned to receive blinatumomab (271 patients) or chemotherapy (134 patients), 376 patients received at least one dose. Overall survival was significantly longer in the blinatumomab group than in the chemotherapy group. The median overall survival was 7.7 months in the blinatumomab group and 4.0 months in the chemotherapy group (hazard ratio for death with blinatumomab vs. chemotherapy, 0.71; 95% confidence interval [CI], 0.55 to 0.93; P = 0.01). Remission rates within 12 weeks after treatment initiation were significantly higher in the blinatumomab group than in the chemotherapy group, both with respect to complete remission with full hematologic recovery (34% vs. 16%, P<0.001) and with respect to complete remission with full, partial, or incomplete hematologic recovery (44% vs. 25%, P<0.001). Treatment with blinatumomab resulted in a higher rate of event-free survival than that with chemotherapy (6-month estimates, 31% vs. 12%; hazard ratio for an event of relapse after achieving a complete remission with full, partial, or incomplete hematologic recovery, or death, 0.55; 95% CI, 0.43 to 0.71; P<0.001), as well as a longer median duration of remission (7.3 vs. 4.6 months). A total of 24% of the patients in each treatment group underwent allogeneic stem-cell transplantation. Adverse events of grade 3 or higher were reported in 87% of the patients in the blinatumomab group and in 92% of the patients in the chemotherapy group. CONCLUSIONS Treatment with blinatumomab resulted in significantly longer overall survival than chemotherapy among adult patients with relapsed or refractory B-cell precursor ALL. (Funded by Amgen; TOWER ClinicalTrials.gov number, NCT02013167.)

BACKGROUND Brentuximab vedotin is an anti-CD30 antibody–drug conjugate that has been approved for relapsed and refractory Hodgkin’s lymphoma. METHODS We conducted an open-label, multicenter, randomized phase 3 trial involving patients with previously untreated stage III or IV classic Hodgkin’s lymphoma, in which 664 were assigned to receive brentuximab vedotin, doxorubicin, vinblastine, and dacarbazine (A+AVD) and 670 were assigned to receive doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD). The primary end point was modified progression-free survival (the time to progression, death, or noncomplete response and use of subsequent anticancer therapy) as adjudicated by an independent review committee. The key secondary end point was overall survival. RESULTS At a median follow-up of 24.9 months, 2-year modified progression-free survival rates in the A+AVD and ABVD groups were 82.1% (95% confidence interval [CI], 78.7 to 85.0) and 77.2% (95% CI, 73.7 to 80.4), respectively, a difference of 4.9 percentage points (hazard ratio for an event of progression, death, or modified progression, 0.77; 95% CI, 0.60 to 0.98; P = 0.03). There were 28 deaths with A+AVD and 39 with ABVD (hazard ratio for interim overall survival, 0.72 [95% CI, 0.44 to 1.17]; P = 0.19). All secondary efficacy end points trended in favor of A+AVD. Neutropenia occurred in 58% of the patients receiving A+AVD and in 45% of those receiving ABVD; in the A+AVD group, the rate of febrile neutropenia was lower among the 83 patients who received primary prophylaxis with granulocyte colony-stimulating factor than among those who did not (11% vs. 21%). Peripheral neuropathy occurred in 67% of patients in the A+AVD group and in 43% of patients in the ABVD group; 67% of patients in the A+AVD group who had peripheral neuropathy had resolution or improvement at the last follow-up visit. Pulmonary toxicity of grade 3 or higher was reported in less than 1% of patients receiving A+AVD and in 3% of those receiving ABVD. Among the deaths that occurred during treatment, 7 of 9 in the A+AVD group were associated with neutropenia and 11 of 13 in the ABVD group were associated with pulmonary-related toxicity. CONCLUSIONS A+AVD had superior efficacy to ABVD in the treatment of patients with advanced-stage Hodgkin’s lymphoma, with a 4.9 percentage-point lower combined risk of progression, death, or noncomplete response and use of subsequent anticancer therapy at 2 years. (Funded by Millennium Pharmaceuticals and Seattle Genetics; ECHELON-1 ClinicalTrials.gov number, NCT01712490; EudraCT number, 2011-005450-60.)

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The purine nucleoside analogs (PNA) form an important group of cytotoxic drugs active in the treatment of neoplastic and autoimmune diseases. Three of them, fludarabine (FA), cladribine (2-chlorodeoxyadenosine, 2-CdA) and pentostatin (2'-deoxycoformycin, DCF) have established clinical activity in hematological malignancies and have been approved by FDA. These drugs are also investigated in some autoimmune diosorders. Recently four novel PNA: clofarabine (CAFdA), nelarabine, immucillin H (BCX-1777, forodesine) and 8-chloroadenosine (8-Cl-Ado) have been synthesized and introduced into clinical trials. All these drugs have chemical structure similar to adenosine or guanosine, however, the mechanism of their action is different. FA, 2-CdA and CAFdA mainly require phosphorylation by deoxynucleoside salvage pathways. The cytotoxic effect exerts the triphosphate metabolites, which are incorporated into DNA, and finally lead to programmed cell death. In contrast, DCF does not need to be phosphorylated and results in an increase of plasma deoxyadenosine (dAdo) levels and intracellular deoxyadenosine triphosphate (dATP). Nelarabine is an arabinosylguanine (ara-G) prodrug, which after conversion to ara-G is phosphorylated to ara-G triphosphate (ara-GTP). Accumulation of ara-GTP finally leads to apoptosis. Forodesine is a purine nucleoside phosphatase (PNP) inhibitor which blocks intracellular deoxyguanine (dGuo) cleaving to guanine (Guo), but instead converts it to deoxyguanosine triphosphate (dGTP), and similarly to other PNA resulting in apoptosis. 8-chloroadenosine (8-Cl-Ado) is a ribonucleoside analog. The mechanism of its action is quite different from other PNA and remains poorly understood. However, it is known that the drug inhibits RNA synthesis, but not DNA. These agents have significant cytotoxic activity against lymphoid and myeloid malignant cells. Moreover, they have deleterious effects on the normal resting lymphocytes. They result in prolonged lymphocyte depletion especially in the CD4 subset of T-cells. Several clinical trials have demonstrated that PNA used alone or in combination with other cytotoxic drugs or monoclonal antibodies shows good efficacy and acceptable toxicity profile in the treatment of lymphoid malignancies. 2-CdA and DCF are drugs of choice in the treatment of hairy cell leukemia. FA and 2-CdA have significant clinical activity in low-grade non-Hodgkin's lymphoma and chronic lymphocytic leukemia. 2-CdA exhibits some activity in progressive multiple sclerosis and other autoimmune disorders. This review will summarize current knowledge concerning the mechanism of action, pharmacological properties, clinical activity and toxicity of PNA accepted for use in clinical practice as well as new agents available for clinical trials.