Prediction of pan-solid tumor pembrolizumab benefit by integrating tumor mutation and gene expression profiling

Pembrolizumab is approved in many advanced solid tumor types, however predictive biomarkers and the proportion of pembrolizumab-benefiting patients vary. Biomarkers beyond PD-L1 immunohistochemistry, microsatellite instability (MSI) status, and tumor mutation burden (TMB) may improve benefit prediction. Here, leveraging treatment data (time to next treatment [TTNT]) and comprehensive genomic and quantitative transcriptomic profiling on routine tumor tissue from 708 patients (24 tumor types) collected in an ongoing observational trial (NCT03061305), we report a multivariate, integrative predictor of pan-solid tumor pembrolizumab benefit. The Immune Response Score (IRS) model, which includes TMB and quantitative PD-1, PD-L2, ADAM12 and CD4 RNA expression, was confirmed as predictive through comparison of pembrolizumab TTNT with previous chemotherapy TTNT in a subset of 166 patients treated with both. Applying IRS to the entire NCT03061305 cohort (n=25,770 patients), 13.2-30.7% of patients (2.2-9.6% of patients outside of pembrolizumab approved tumor types [including TMB-High and MSI-High]) are predicted to benefit substantially from pembrolizumab. Hence, if prospectively validated, the IRS model may improve pembrolizumab benefit prediction across approved tumor types including patients outside of currently approved indications.

Clinical and utilization outcomes associated with tumor mutational burden in a real-world pan-tumor population

Aim & methods: This real-world study examined the association of tumor mutational burden (TMB) with clinical and healthcare utilization in adults diagnosed with advanced solid tumor 1 January 2015– 31 January 2019. Results: There were 170 patients in low-TMB group (TMB<10 mut/Mb) and 32 in high-TMB group (TMB ≥10 mut/Mb). Median overall survival was 18.8 (95% CI: 17.3–28.8) and 15.9 months (95% CI: 11.3–18.0) whereas median progression-free survival was 9.9 (95% CI: 8.6–11.4) and 7.8 months (95% CI: 3.8–12.5) for the low- and high-TMB groups, respectively. Hospitalization (49.4 vs 37.5%), emergency visit (25.3 vs 21.9%), and median overall cost of care (US$135,403 vs 87,570) were all lower in low-TMB group. Conclusion: Despite the limited sample, these data provide a historical perspective for examining real-world outcomes associated with TMB.

Treatment beyond progression with anti-PD-1/PD-L1 based regimens in advanced solid tumors: a systematic review

Background Treatment beyond progression with immunotherapy may be appropriate in selected patients based on the potential for late responses. The aim of this systematic review was to explore the impact of treatment beyond progression in patients receiving an anti-PD-1/PD-L1 based regimen for an advanced solid tumor. Methods A systematic literature search was performed to identify prospective clinical trials reporting data on overall response rate by immune-related criteria and/or the number of patients treated beyond conventional criteria-defined PD and/or the number of patients achieving a clinical benefit after an initial PD with regimens including an anti-PD-1/PD-L1 agent which received the FDA approval for the treatment of an advanced solid tumor. Results 254 (4.6%) responses after an initial RECIST-defined progressive disease were observed among 5588 patients, based on 35 trials included in our analysis reporting this information. The overall rate of patients receiving treatment beyond progressive disease was 30.2%, based on data on 5334 patients enrolled in 36 trials, and the rate of patients who achieved an unconventional response among those treated beyond progressive disease was 19.7% (based on 25 trials for a total of 853 patients). Conclusion The results of our systematic review support the clinical relevance of unconventional responses to anti-PD-1/PD-L1-based regimens; however, most publications provided only partial information regarding immune-related clinical activity, or did not provide any information at all, highlighting the need of a more comprehensive report of such data in trials investigating immunotherapy for the treatment of patients with advanced tumors.