The Capitello-291 trial for capivasertib missed its overall survival (OS) endpoint. However, this was likely confounded by the trial being underpowered for this endpoint and a significant imbalance in subsequent targeted therapies received by the placebo arm (42.5% vs 26%), which likely diluted the observable survival benefit of capivasertib.
Real-world use of capivaseratib reveals more challenging rash and diarrhea than trial data may suggest. The speaker recommends proactive management with non-sedating antihistamines starting the day *before* therapy and prophylactic loperamide. This strategy, combined with dose reductions that don't compromise PFS, is key for patient tolerance.
While ctDNA is a powerful tool, it is not interchangeable with tissue testing for PI3K pathway alterations. Analysis from Capitello-291 showed PTEN deletions were the most discordant, with 11% of pathway alterations found only in tissue. This highlights the need for a complementary strategy, using both methods to ensure all eligible patients are identified for targeted therapy.
A key toxicity of the dual PI3K/mTOR inhibitor getatolisib is grade 3 stomatitis, which occurs despite standard steroid mouthwash. Its rapid onset, with a median time of just four days, makes prevention difficult. Because it's an IV drug, patients cannot simply hold a dose at the first sign of symptoms, requiring clinicians to be highly vigilant in the first week of treatment.
The VICTORIA-1 trial demonstrated remarkable efficacy for the getatolisib/palbociclib/fulvestrant triplet in patients *without* PIK3CA mutations. Its ability to nearly quadruple median PFS versus fulvestrant alone (9.3 vs 2.6 months) in this wild-type population addresses a major unmet need, as these patients previously lacked effective targeted therapies in the PI3K/mTOR pathway.
Unlike earlier PI3K inhibitors notorious for severe hyperglycemia and rash, new pan-mutant selective agents tersolasib and zovagelisib have remarkably improved safety profiles. Tersolasib's most common grade 3 event was manageable liver enzyme elevation (7%), not the class-defining toxicities. This superior tolerability could enable broader use and better patient compliance.
A subgroup analysis from Capitello-291 suggests patients treated with capivasertib in the first-line setting experienced less diarrhea and rash than those in later lines. This aligns with a broader trend where heavily pre-treated patients exhibit poorer drug tolerance. This finding supports considering potent targeted agents earlier in the treatment sequence to potentially improve tolerability and outcomes.