G1 Therapeutics Fails Late-Stage Breast Cancer Trial, Plans ‘Targeted’ Headcount Reductions

Pictured: A digital mammogram of the breast to dia

Pictured: A digital mammogram of the breast to dia

G1 Therapeutics on Monday reported Phase III study results showing its drug Cosela did not demonstrate a statistically significant effect in overall survival in triple-negative breast cancer patients.

Pictured: Digital mammogram used to diagnose breast cancer/iStock, mr.suphachai praserdumrongchai

G1 Therapeutics announced Monday that its drug Cosela (trilaciclib) in a Phase III trial failed to show a statistically significant treatment effect in triple-negative breast cancer patients, as the company takes measures to reach profitability in the second half of 2025.

Cosela was investigated in the PRESERVE 2 trial for its efficacy and safety in patients with triple-negative breast cancer (TNBC) before taking chemotherapy. The results showed no statistically significant effect on the intent to treat the population, displaying a hazard ratio of 0.91 and a p-value of 0.884.

The median overall survival rate in the Cosela and chemo arm was 17.4 months compared to 17.8 in the control arm. The median overall survival “numerically favored” Cosela in the PD-L1 positive and negative subgroups, but neither reached statistical significance.

G1 plans to evaluate the findings and said no new safety signals were found. The company also intends to submit the results at an unnamed medical conference.

Based on the results, G1 said it will “wind down” the Phase III PRESERVE 2 trial, stop hiring staff and halt investment in a first-line TNBC indication. It also intends to make a “targeted headcount reduction” to streamline the company, but no specific numbers were provided by the company.

G1 said these efforts are expected to provide G1 with enough of a cash runway to achieve profitability in the second half of 2025. However, G1’s stock price dropped by more than 50% in premarket trading on Monday.

“The unexpected results from PRESERVE 2 underscore the challenge of developing new therapies for triple-negative breast cancer,” G1 CEO Jack Bailey said in a statement. “We are disappointed that this trial did not deliver the benefit that we anticipated to people living with TNBC.”

Bailey said the company is now focusing on accelerating and expanding its extensive-stage small cell lung cancer (ES-SCLC) business, which he says will help “achieve anticipated company profitability” in the second half of next year. G1 is evaluating other myeloprotection uses for Cosela and pushing for ex-U.S. partners to expand the drug’s use globally.

Cosela was approved by the FDA in 2021 to reduce the frequency of chemotherapy-induced bone marrow suppression in adults taking chemotherapy to treat ES-SCLC. The company’s first commercial product is expected to generate between $60 million and $70 million in net revenue this year.

Tyler Patchen is a staff writer at BioSpace. You can reach him at tyler.patchen@biospace.com. Follow him on LinkedIn.