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Calithera Biosciences Ends Telaglenastat Development Program After Second Trial Failure

NEW YORK – Calithera Bioscences on Friday said it would discontinue its Phase II KEAPSAKE clinical trial investigating telaglenastat plus pembrolizumab (Merck's Keytruda) and chemotherapy as a front-line treatment for non-small cell lung cancer patients with a KEAP1 or NRF2 mutation.

Moreover, the company has decided to entirely shutter the telaglenastat program since this is the second clinical trial of the drug it has had to discontinue due to lackluster efficacy. Earlier this year, Calithera had to stop another study of telaglenastat in renal cell carcinoma after it failed to meet the primary endpoint.

In the KEAPSAKE study, which began in September 2020, Calithera hoped to enroll 120 stage IV NSCLC patients and randomize them to receive either telaglenastat-pembrolizumab-chemo or just the immunotherapy-chemo combination. At the time of unblinding, 40 NSCLC patients had enrolled in the trial, but there wasn't a treatment benefit seen in the telaglenastat arm in terms of investigator-assessed progression-free survival. The South San Francisco, California-based company said in a statement that "there was a very low probability for the study to achieve a positive result."

Calithera will now focus on developing its recently acquired oncology compounds, sapanisertib and mivavotinib, along with its therapeutic candidates for cystic fibrosis. It purchased the two cancer drugs from Takeda last month in a $45 million deal. Sapanisertib is being investigated as a treatment for patients with NRF2-mutated NSCLC, and mivavotinib is being studied as a therapy for patients with non-Hodgkin's lymphoma and diffuse large B-cell lymphoma with MyD88 or CD79 mutations.