Brief Report: Post Hoc Validation of Platinum Ineligibility in NSCLC From the Phase III IPSOS Study

The phase III IPSOS study (NCT03191786) demonstrated that atezolizumab was associated with improved survival, stable patient-reported outcomes, and a favorable safety profile versus single-agent chemotherapy in patients with NSCLC ineligible for platinum-based chemotherapy. As no established consensus criteria for platinum ineligibility exist for NSCLC, we performed a post hoc analysis from IPSOS to evaluate clinical outcomes in a selected platinum-ineligible (sPI) population meeting a refined definition.

Patients with stage IIIB or IV NSCLC who were ineligible for platinum-doublet chemotherapy were randomized (2:1) to receive atezolizumab or single-agent chemotherapy (vinorelbine or gemcitabine). Patients in the sPI subgroup were defined as those with Eastern Cooperative Oncology Group performance status of 3, age older than 80 years, Eastern Cooperative Oncology Group performance status of 2 with relevant comorbidities, or age 70 years or older with relevant comorbidities.

Of 453 patients from the IPSOS intention-to-treat population, 405 (89%) met sPI criteria. Compared with chemotherapy, atezolizumab improved overall survival (unstratified hazard ratio 0.78; 95% confidence interval: 0.63-0.98). Atezolizumab was associated with fewer grade 3 or 4 treatment-related adverse events (46 of 266 [17.3%] versus 46 of 134 [34.3%] with chemotherapy), grade 5 treatment-related adverse events (two of 266 [0.8%] versus four of 134 [3.0%]), and stabilization or improvement of patient-reported health-related quality of life.

This subanalysis suggests that first-line treatment with atezolizumab provides long-term overall survival, consistent with the results from the intention-to-treat population, and a favorable safety profile compared with single-agent chemotherapy in the sPI population. In addition, the selection criteria for platinum ineligibility from the sPI population may provide a structured approach for treatment selection in NSCLC in clinical practice.