Slammed with PhII flop for lead drug, Calithera lays off a third of its staffers

Calithera Biosciences will be going into the new year with only two-thirds of its staff.

The South San Francisco-based biotech is laying off “around 30 employees,” it told Endpoints News — or 35% of its total workforce — in the wake of a Phase II flop. Adding Calithera’s telaglenastat to Exelixis’ Cabometyx, the investigators concluded, failed to improve progression-free survival for patients with renal cell carcinoma.

By the numbers, patients on Cabometyx and placebo actually lived slightly longer — a PFS of 9.3 months compared to 9.2 months for those treated with telaglenastat and Cabometyx, but at this point it doesn’t mean much. The hazard ratio of 0.94 was far off statistical significance (p=0.65), quashing previous hopes of taking the data to the FDA for potential registration.

While disappointed, president and CEO Susan Molineaux’s faith in the drug has remained.

“Based on the strong scientific rationale for telaglenastat in KEAP1/NRF2 mutant non-small cell lung cancer patients, and the safety profile observed in CANTATA, we remain dedicated to advancing our randomized KEAPSAKE trial,” she said in a statement.

Also dubbed CB-839, telaglenastat is a glutaminase inhibitor designed to cut off glutamine consumption in tumor cells, which are more dependent on glutamine than normal cells.

The KEAPSAKE trial started in September, and Calithera said the $115 million in its reserves should keep it afloat through a readout later this year to 2022. It is also running a study of CB-280, an arginase inhibitor, for cystic fibrosis that is partially supported by the CF Foundation, on top of other pipeline programs. These ongoing programs will be its focus for now, it noted, hinting that the layoffs likely target drug discovery and research units.

Following the restructuring, around 60 employees will remain at Calithera.

Although an array of players have proposed new ways to treat RCC, I/O therapies and tyrosine kinase inhibitors such as Inlyta and Cabometyx are still dominant.

In total, the CANTATA trial enrolled 444 patients, 62% of whom were treated with prior PD-(L)1-containing therapy. All had had one or two lines of systemic therapy, including at least one drug targeted at the VEGF pathway or the Yervoy/Opdivo combo.

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