Multicenter validation of an assay to predict anti-PD-1 disease control in patients with recurrent or metastatic Head and Neck Squamous Cell Carcinoma: The PREDAPT Study

BackgroundDespite advances in cancer care and detection, more than 65% of patients with squamous cell cancer of the head and neck (HNSCC) will develop recurrent and/or metastatic disease. The prognosis for these patients is poor with a 5 year overall survival of 39%. Recent treatment advances in immunotherapy, including immune checkpoint inhibitors like pembrolizumab and nivolumab, have resulted in clinical benefit in a subset of patients. There is a critical clinical need to identify patients who benefit from these anti-PD-1 immune checkpoint inhibitors. MethodsHere we report findings from a multi-center observational study, PREDAPT (ClinicalTrials.gov: NCT04510129), conducted across 17 US healthcare systems. PREDAPT aimed to validate OncoPrism-HNSCC, a clinical biomarker assay predictive of disease control in recurrent or metastatic HNSCC patients treated with anti-PD-1 immune checkpoint inhibitors as a single agent (monotherapy) and in combination with chemotherapy (chemo-immunotherapy). The test used RNA-sequencing data and machine learning models to score each patient and place them into groups of Low, Medium, or High. ResultsThe OncoPrism-HNSCC prediction significantly correlated with disease control in both the monotherapy cohort (n=62, p=0.004) and the chemo-immunotherapy cohort (n=50, p=0.01). OncoPrism-HNSCC also significantly predicted progression-free survival in both cohorts (p=0.015 and p=0.037, respectively). OncoPrism-HNSCC had more than threefold higher specificity than PD-L1 combined positive score and nearly fourfold higher sensitivity than tumor mutational burden for predicting disease control. ConclusionsHere we demonstrate the clinical validity of the OncoPrism-HNSCC assay in identifying patients with disease control in response to anti-PD-1 immune checkpoint inhibitors. WHAT IS ALREADY KNOWN ON THIS TOPICAnti-PD-1 immune checkpoint inhibitors such as pembrolizumab benefit a subset of patients with recurrent or metastatic head and neck squamous cell carcinoma (RM- HNSCC), but current biomarkers are inadequate at identifying these patients. WHAT THIS STUDY ADDSThis study describes the validation of a new RNA-based test that predicts disease control and progression-free survival in response to anti-PD-1 therapy with high sensitivity and specificity. The test was validated using two independent cohorts of patients from 17 community and academic sites. HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICYThe test had significantly higher sensitivity than TMB and significantly higher specificity than PD-L1, enabling clinicians to make more informed decisions when prioritizing treatment. Use of the test has the potential to avoid unnecessary chemotherapy and/or anti-PD-1 treatment and improve patient outcomes.