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Calithera Biosciences Begins Phase II Trial of Mivavotinib in DLBCL

NEW YORK – Calithera Biosciences on Thursday said that it has enrolled the first patient in a Phase II trial of its SYK inhibitor mivavotinib for patients with non-germinal center B-cell-like diffuse large B-cell leukemia.

The study will seek to confirm previous studies that have shown mivavotinib's activity in that setting and evaluate the drug in cancer patients with MYD88 and CD79b mutations as determined by centrally performed ctDNA-based next-generation sequencing. About 50 patients with and without those mutations will be randomized to two arms. In one arm, patients will receive a continuous 100 mg daily dose, while in the other, patients will start at a dose of 120 mg per day for 14 days and then step down to 80 mg per day on day 15.

The study's primary endpoint is overall response rate. Calithera will also assess patients' duration of response, progression-free survival, and complete response.

In a retrospective analysis of prior Phase I/II studies, 53 percent of patients with non-GCB DLBCL responded to mivavotinib compared to 22 percent of GCB DLBCL on the treatment. Preclinical studies have suggested that DLBCL tumor cell lines with mutations in MYD88 and CD79b are more sensitive to SYK inhibition.

The South San Francisco, California-based company is also evaluating the TORC 1/2 inhibitor sapanisertib in NRF2-mutated squamous non-small cell lung cancer in a Phase II trial. In March, it raised $10 million in gross proceeds in a public stock offering to advance mivavotinib and sapanisertib into Phase II clinical trials and fund its other discovery and development programs.