Ignite Proteomics presents data on MHC-II as predictor of pembrolizumab response

Ignite Proteomics announced the presentation of new data demonstrating that MHC-II protein expression is a superior predictor of response to pembrolizumab compared to PD-L1 at the upcoming National Comprehensive Cancer Network Annual Conference. The study, conducted with I-SPY 2 clinical trial results, evaluated five different PD-L1 antibodies – including the one most commonly used as a companion diagnostic – yet only MHC-II expression showed a statistically significant correlation with patient outcomes. I-SPY 2 is a multicenter, adaptive platform trial primarily focused on high-risk stage II and III breast cancer patients undergoing neoadjuvant treatment. The design rapidly evaluates new agents – such as checkpoint inhibitors – based on interim outcomes like pathologic complete response. Data from I-SPY 2 often guides further clinical development in breast cancer, underscoring the significance of MHC-II outperforming PD-L1 measurements in this well-regarded research setting. Five PD-L1 Antibodies Tested: Only MHC-II correlated with response to pembrolizumab, whereas none of the five PD-L1 measurements reached statistical significance. Improved Patient Outcomes: Patients with higher MHC-II protein levels demonstrated nearly double the response rate compared to the unselected patient cohort. Unmet Need in Some Indications: For some cancers and settings where no biomarker testing is used, a large fraction of patients do not respond to checkpoint inhibitors. This study suggests MHC-II testing can enrich for those more likely to benefit.