Baseline Tumor Size and Prognosis in Pembrolizumab-Treated Melanoma
Posted: Monday, June 25, 2018
Baseline tumor size, independent of other baseline clinical factors, was found to be prognostic of overall survival in 583 patients with advanced melanoma who were treated with pembrolizumab, according to a retrospective study performed by Richard W. Joseph, MD, of Mayo Clinic, Jacksonville, Florida, and colleagues. Their work, published in Clinical Cancer Research, centered on patients participating in KEYNOTE-001 who had baseline measurable disease (583 of a total of 655).
The baseline tumor size was quantified, the authors explained, “by adding the sum of the longest dimensions of all measurable baseline target lesions.” The median size was 10.2 cm, with a range of 1.0 cm to 89.5 cm. The baseline tumor size below the median was found to be significantly associated with improved overall survival, using both univariate and multivariate analyses, and with higher objective response rate, using univariate but not multivariate analyses. Over the median, the baseline tumor size was significantly associated with an Eastern Cooperative Oncology Group performance status 1, elevated lactate dehydrogenase level, stage M1c disease, and metastases to the liver (with or without any other sites).
“Although this analysis cannot differentiate the predictive versus prognostic effect of baseline factors, we hypothesize that [baseline tumor size] represents a distinct balance between tumor antigen burden and the preexisting ineffective immune response that, when adequately augmented by PD-1 blockade, can result in an effective antitumor response,” Dr. Joseph and colleagues wrote.