Calithera Biosciences Inc. (NASDAQ: CALA) Terminates Phase 2 KEAPSAKE Study Due Telaglenastat’s Lack of Clinical Benefit

Calithera Biosciences Inc. (NASDAQ: CALA) has announced a decision to discontinue its second phase KEAPSAKE clinical study because of failure to observe clinical benefit in the preliminary analysis of patients that received telaglenastat.

Calithera discontinues KEAPSAKE study 

CEO Susan Molineaux said, “We are disappointed in this outcome for the KEAPSAKE trial, but it was a well-run study with an interim analysis that gave us an answer to an important clinical question. We also want to express our sincere gratitude to the patients who participated in the trial and their families, as well as the physicians who served as investigators for the trial and their site staff.”

Molineaux added, “We remain committed to patients with difficult-to-treat cancers and will continue to advance our investigational targeted therapies for biomarker-specific patient populations. Our near-term clinical development plans include leveraging our clinical and biomarker expertise in the KEAP1/NRF2 pathway in the development of our mTORC1/2 inhibitor sapanisertib in squamous non-small cell lung cancer, as well as advancing the development of our SYK inhibitor mivavotinib in specific biomarker-defined populations of diffuse large B-cell lymphoma. In addition, we are continuing the development of our arginase inhibitor CB-280 for the treatment of cystic fibrosis.”

KEAPSAKE evaluated the safety of telaglenastat 

The KEAPSAKE research was meant to assess the safety and antitumor activity of telaglenastat in combination with standard-of-care chemoimmunotherapy as in patients with stage IV non-squamous non-small cell lung cancer (NSCLC)  with NRF2 or KEAP1 mutation tumors.

At unblinding, efficacy data available, including investigator-assessed progression-free survival (PFS), did not show clinical benefit. An examination of the data resulted in the conclusion that the study had a very low chance of producing a positive result. In addition, there was no variation in the safety profile between the two arms. Calithera has informed the US FDA of its findings and has voluntarily terminated the phase 2 trial with the approval of the KEAPSAKE Steering Committee. The company currently has no plans to continue developing telaglenastat. Calithera predicts a cost savings of $10-15 million as a result of the trial’s cancellation.