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Concordance of pathologic response assessment between local and central review in melanoma: a post hoc analysis of
M Tetzlaff1, J M Taube2, G V Long3
1Departments of Pathology and Dermatology, Dermatopathology and Oral Pathology Unit, University of California San Francisco, San Francisco, USA.
Background:
Substudy 02C of the phase I-II KEYMAKER-U02 study was designed to evaluate neoadjuvant pembrolizumab as monotherapy and in combination with investigational agents, followed by surgery and adjuvant pembrolizumab in participants with resectable stage IIIB-D melanoma. Here, we report a post hoc analysis of concordance of pathologic response assessment between local and central review and among central reviewers in the KEYMAKER-U02 substudy 02C.
Patients And Methods:
Participants received neoadjuvant pembrolizumab plus vibostolimab, pembrolizumab plus gebasaxturev, or pembrolizumab monotherapy followed by resection and adjuvant pembrolizumab. Pathologic response was categorized by percent age of residual viable tumor (%RVT) in the treated tumor bed as follows: pathologic complete response (pCR; 0% RVT), near-pCR (RVT >0% but ≤10%), partial pathologic response (pPR; RVT >10% but ≤50%), and pathologic nonresponse (pNR; RVT >50%).
Results:
By local review of 60 participants, 24 (40%) had pCR, 7 (12%) had near-pCR, 12 (20%) had pPR, and 17 (28%) had pNR. By central review of 60 participants, 23 (38%) had pCR, 7 (12%) had near-pCR, 14 (23%) had pPR, and 16 (27%) had pNR. The weighted kappa for concordance between local and central review for these categories was 0.79 (95% CI 0.70-0.89). The three central reviewers agreed on the response category for 54 of 61 participants (89%). For the seven participants (11%) without agreement, the maximum difference in response was one category; for four of these participants, the dissenting response assessment was close to a %RVT category cut point. The weighted Gwet's agreement coefficient was 0.94 (95% CI 0.90-0.98).
Conclusion:
These results confirm a high level of concordance in pathologic response assessment between local and central review and among central reviewers and provide confidence in the accuracy of pathologic response assessment following neoadjuvant therapy.