Efficacy Findings: Response and Disease Control Rates

Efficacy Findings: Response and Disease Control Rates

The KEYNOTE-B61 study demonstrated remarkable efficacy results with an objective response rate of 50.6% across all histologies, representing a substantial improvement over historical outcomes in non–clear cell RCC. The disease control rate reached 82%, meaning the overwhelming majority of patients achieved at least stable disease or better. Approximately 10% of patients achieved complete responses, while the remainder of responses were partial responses, establishing a memorable clinical benchmark of roughly 50% response rate and 82% disease control rate for clinicians treating this patient population.

When efficacy was analyzed by specific histologic subtype, response rates varied across the spectrum but remained encouraging even in traditionally immunotherapy-resistant subtypes. Chromophobe RCC, which comprises 18% of the study population and historically has not been considered highly immunoresponsive, still achieved a 31% response rate. This finding is particularly significant as it provides substantial data supporting immunotherapy-based regimens for patients with chromophobe RCC, a population that previously lacked strong evidence for this treatment approach.

The waterfall plot analysis revealed that tumor burden reduction occurred in nearly all patients, regardless of whether they met formal RECIST response criteria requiring at least a 30% reduction in target lesions. This finding demonstrates broad antitumor activity across all histologic subtypes including papillary, chromophobe, unclassified, translocation, and other variants. The median duration of response was 23.5 months, approximately 2 years, indicating durable benefit for responding patients. These results establish a new treatment standard, dramatically surpassing historical response rates of less than 25% to 30% seen with TKI monotherapy, with complete response rates previously below 5%. Only 10% of patients experienced disease progression at first assessment, translating to a 90% chance of avoiding early treatment failure.