Comparison of RECIST to immune-related response criteria in patients with non-small cell lung cancer treated with immune-checkpoint inhibitors.

PURPOSE

Given that immune-related response in non-small cell lung cancer (NSCLC) has not been well evaluated, we assessed tumor response using the response evaluation criteria in solid tumors, version 1.1 (RECIST v1.1) and immune-related response criteria (irRC) to identify atypical responses in patients with advanced NSCLC treated with immunotherapeutic agents.

METHODS

Patients received immune-checkpoint inhibitors (pembrolizumab, atezolizumab, nivolumab, and durvalumab plus tremelimumab) to treat metastatic or recurrent NSCLC after failed platinum-based chemotherapy. Tumor response was assessed according to both RECIST v1.1 and irRC.

RESULTS

Responses by 41 patients were analyzed. The overall response rate (ORR) was 29.2% (95% CI 17.6-44.5) assessed by RECIST v1.1 and 34.1% (95% CI 21.6-49.4) by irRC, showing similar results from the two methods (p = 0.923). Two patients (4.9%) were defined as having progressive disease as assessed by RECIST but not by irRC. The patients eventually experienced tumor regression, suggesting delayed pseudoprogression. For all patients, the median PFS was 5.1 months (95% CI 3.4-6.7) and OS was 18.3 months (95% CI 6.7-29.8). In multivariate analysis, ex- or current smokers (HR 0.34, p = 0.14) and EGFR mutation negativity (HR 0.16, p = 0.05) were associated with significantly longer PFS.

CONCLUSION

Our study found that pseudoprogression was not frequently observed in NSCLC. Conventional RECIST v1.1 might underestimate the benefit of immune-checkpoint inhibitors. Given the small number of patients studied, further study is warranted on whether treatment with immune-checkpoint inhibitors beyond RECIST progression benefits patients with advanced NSCLC.