G1 Therapeutics, Inc. announced topline results from the final OS analysis of its Phase 3 PresERVE 2 trial evaluating the efficacy and safety of trilaciclib administered prior to chemotherapy (gemcitabine and carboplatin; GCb) in patients with metastatic TNBC. The study did not demonstrate a statistically significant treatment effect in the ITT population (n=187) with a hazard ratio (HR) of 0.91 (p=0.884). The median OS in the trilaciclib plus GCb arm was 17.4 months compared to 17.8 months in the control arm.

Median OS numerically favored the trilaciclib arm in both PD-L1 subgroups (positive and negative), though neither achieved statistical significance. Varying effects were observed across regions and patients who received different types of subsequent therapies; these findings will be evaluated further. The safety profile of trilaciclib with GCb observed in the trial was consistent with prior studies, and no new safety signals were identified.

Consistent with other trilaciclib studies, evidence of myeloprotection was observed, including a reduction in the occurrence of severe neutropenia, which occurred in 8% of patients who received trilaciclib compared to 29% of patients in the control arm.