Correlative study using immuno-MRM in the Cancer Immunotherapy Trials Network (CITN-10) phase 2 clinical trial of pembrolizumab for the treatment of refractory or relapsed Mycosis fungoides (MF) and Sezary syndrome (SS)

MF and SS are common subtypes of cutaneous T-cell lymphomas with poor response rates to systemic therapies. Treatments targeting immune checkpoint molecules, like PD-1, have been associated with 15-38% overall response rates in the MF type T-cell lymphomas (Lesokhin et al., 2016; Khodadoust et al., 2020). Thus, correlative, predictive markers of response to identify patients most likely to respond to targeted therapy would be highly beneficial. Using a linear mixed effects regression model, we identified ten peptides with significant abundance changes (adjusted p-value <0.05) in plasma and serum across the pre-treatment (Pre), cycle-2 (C02), and end-of-treatment (EOT) time points. Two peptides, corresponding to IL6R and MST1, respectively, showed significant differences between the response classes.