Phase I study of bryostatin 1 in patients with relapsed non-Hodgkin's lymphoma and chronic lymphocytic leukemia

Purpose: To define, in a phase I study in relapsed non-Hodgkin's lymphoma (NHL) and chronic lymphocytic leukemia (CLL), the maximum-tolerated dose (MTD), major toxicities, and possible antitumor activity of bryostatin 1, a macrocyclic lactone. Patients and Methods: Bryostatin 1 was delivered by 72-hour continuous infusion every 2 weeks to patients with relapsed NHL or CLL, at doses that ranged from 12 mu g/m(2) to 180 mu g/m(2) per course. Correlative investigations included evaluations of total protein kinase C (PKC) in peripheral blood and lymphoid differentiation in patient tumor tissue. Results: Twenty-nine patients were treated, including three patients with CLL and 26 with NHL. Generalized myalgia was the dose-limiting toxicity (DLT) and occurred in two of three patients treated with bryostatin 1 at 180 mu g/m(2) per course. Myalgias were dose-related and cumulative, and often started in the thighs and calves, improved with activity, were somewhat responsive to analgesics, and often took weeks to resolve once taken off study Six patients were treated at the MTD of 120 mu g/m(2) pel course. Myalgia, headache, and fatigue were common, Hematologic toxicity was uncommon. Total cumulative doses of bryostatin 1 up to 1,134 mu g/m(2) have been administered without untoward toxicity. Eleven patients achieved stable disease for 2 to 19 months. An in vitro assay for total PKC evaluation in patient peripheral-blood samples demonstrated activation within the first 2 hours with subsequent down-regulation by 24 hours, which was maintained throughout the duration of the 72-hour infusion. Conclusion: This phase 1 study defined the MTD and recommended phase II dose of bryostatin 1, when administered over 72 hours every 2 weeks, to be 120 mu g/m(2) (40 mu g/m(2)/d for 3 days). Generalized myalgia was the DLT. Future studies will define the precise activity of bryostatin 1 in subsets elf patients with lymphoproliferative malignancies and its efficacy in combination with other agents. (C) 1998 by American Society of Clinical Oncology.