As a single agent for use in patients with lymphoma, an acceptable once-daily dose of OTX015 appears to be 80 mg on a 14 days on, 7 days off, schedule, the results of a phase 1 study indicate.

The small-molecule inhibitor, which inhibits binding of bromodomain and exterminal proteins to acetylated histones, was associated with acceptable toxicity and efficacy in this regimen. The investigational drug is now being tested in expansion cohorts on a schedule of 14 days every 3 weeks, a regimen projected to allow for recovery from the drug’s toxic effects, Dr. Sandy Amorin of Hôpital Saint Louis, Paris, and associates reported.

The drug also is being evaluated in patients with acute leukemias.

Adults with nonleukemia hematologic malignancies that progressed on standard therapies participated in the open-label study, which was conducted at seven university hospital centers in Europe. Oral OTX015 was given once a day at one of five doses (10 mg, 20 mg, 40 mg, 80 mg, and 120 mg). The 3 + 3 study design permitted evaluation of alternative administration schedules. The primary endpoint was dose-limiting toxicity in the first treatment cycle (21 days). Secondary objectives were to evaluate safety, pharmacokinetics, and preliminary clinical activity of OTX015. The study is ongoing and is registered with, number NCT01713582 .

The study included 33 patients with lymphoma and 12 with myeloma; patients’ median age was 66 years, and they had received a median of four lines of prior therapy. No dose-limiting toxicities were seen in three patients given doses as high as 80 mg once a day. However, grade 4 thrombocytopenia occurred in five of six patients on a 21-day schedule of 40 mg twice a day. No patient tolerated various schedules of 120 mg once a day ( Lancet Haematol. 2016;3[4]:e196-204 ).

The researchers then examined the 80 mg once a day dose on a continuous basis in four patients, two of whom developed grade 4 thrombocytopenia. In light of these and other toxicities, a regimen was proposed of 80 mg once a day on a schedule of 14 days on, 7 days off.

Thrombocytopenia affected 43 of 45 patients, and 26 of them had grade 3-4 events. Other grade 3-4 events were infrequent. Anemia was seen in 41, and neutropenia in 23.

Of three patients with diffuse large B-cell lymphoma, two had complete responses at 120 mg once a day, and one had a partial response at 80 mg once a day. Six additional patients, two with diffuse large B-cell lymphoma and four with indolent lymphomas, had evidence of clinical activity, but did not meet the criteria for an objective response.

The study was funded by the developers of OTX015, Oncoethix GmbH, a wholly owned subsidiary of Merck Sharp & Dohme.

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