Abstract 2224: Validated differential expression of immunoregulatory molecules that coincide with targetable mutations may provide novel insights into strategic trial design for therapeutics

Tumor Infiltrating Lymphocyte Expression of PD-1 Predicts Response to Anti-PD-1/PD-L1 Immunotherapy

INTRODUCTION

Many studies have focused on the role of programmed death receptor ligand 1 (PD-L1) expression in predicting immunotherapy outcomes. Limited clinical data are available regarding the role of programmed death receptor 1 (PD-1; the PD-L1 receptor) expressing tumor-infiltrating lymphocytes (TILs) in PD-1/PD-L1 antibody responsiveness. However, preclinical studies demonstrate that TILs expressing PD-1 contribute to tumor immune evasion.

METHODS

This study analyzed the association between TIL-PD-1 status and outcome after immune checkpoint blockade (ICB) therapy. We evaluated 123 patients with various solid tumors treated with monoclonal antibodies targeting the PD-1/PD-L1 signaling axis. Additionally, 8706 solid tumor specimens were assessed for TIL-PD-1 and tumor mutational burden (TMB) status.

RESULTS

The presence of PD-1-expressing TILs in tumors was associated with increased median progression-free survival (7.0 vs 1.9 months; p = 0.006) and overall survival (18.1 vs 8.0 months; p = 0.04) after treatment with ICB. TIL-PD-1-positive patients had an objective response rate (ORR) of 41% (95% CI, 24-61; N = 12/29) compared with 17% (95% CI, 4-43; N = 3/17) for TIL-PD-1-negative patients (p = 0.18). Analyzed as continuous variables, TIL-PD-1 and TMB showed a weak correlation in 8706 solid tumor samples (Pearson r = 0.074); when analyzed as categorical variables (cutoffs: TIL-PD-1 ≥ 1% and TMB ≥ 10 mutations/Mb), the two variables are correlated (p < 0.0001). TIL-PD-1-positive status is also associated with enrichment of pathologic variants within several genes, most notably TP53 (adjusted p < 0.05).

CONCLUSION

TIL-PD-1 positivity in tumors (≥ 1%) is associated with significantly longer progression-free and overall survival after ICB. ClinicalTrials.gov ID: NCT02478931.

First-line Immune Checkpoint Inhibitor Combinations in Metastatic Renal Cell Carcinoma: Where Are We Going, Where Have We Been?

The combination of targeted therapy and immunotherapy in the treatment of metastatic renal cell carcinoma (mRCC) has significantly improved outcomes for many patients. There are multiple FDA-approved regimens for the frontline setting based on numerous randomized Phase III trials. Despite these efforts, there remains a conundrum of identifying a biomarker-driven approach for these patients and it is unclear how to predict which patients are most likely to respond to these agents. This is due, in part, to an incomplete understanding of how these drug combinations work. The use of tyrosine kinase inhibitors that have multiple 'off-target' effects may lend themselves to the benefits observed when given in combination with immunotherapy. Further, targeting multiple clones within a patient's heterogenic tumor that are responsive to targeted therapy and others that are responsive to immunotherapy may also explain some level of improved response rates to the combination approaches compared to monotherapies. This review highlights the 5 FDA-approved regimens for mRCC in the frontline setting and offers insights into potential mechanisms for improved outcomes seen in these combination approaches.