John F. Seymour, MBBS, FRACP, PhD, discusses the efficacy of single-agent ABT-199 (GDC-0199), a novel Bcl-2 inhibitor, in high-risk relapsed or refractory chronic lymphocytic leukemia and small lymphocytic lymphoma.
John F. Seymour, MBBS, FRACP, PhD, from the Department of Hematology at the Peter MacCallum Cancer Centre in East Melbourne, Australia, discusses the efficacy of single-agent ABT-199 (GDC-0199), a novel Bcl-2 inhibitor, in high-risk relapsed or refractory chronic lymphocytic leukemia (CLL) and small lymphocytic lymphoma (SLL).
In the phase I trial, 56 patients received treatment with ABT-199 at doses from 150 mg to 1200 mg. The overall response rate for patients treated with ABT-199 was 84% with a complete remission rate of 23%, Seymour notes. In general, 90% of patients had received prior treatment with fludarabine with approximately 50% of patients developing fludarabine resistance. On average, patients received 4 median treatments prior to receiving ABT-199, representing a very heavily pretreated patient population.
Furthermore, Seymour says, response rates were sustained in patients with 17p deletions, which have conventionally indicated a poor response to treatment. In a phase I context, this agent has generated exciting response across poor prognostic groups, Seymour notes.
Although it was not a prospective objective of the trial, local labs completed 4-color flow cytometry. Overall, 8 patients tested negative for minimal residual disease. In the context of a single agent in relapsed and refractory CLL, this agent has demonstrated very encouraging efficacy, Seymour believes.