Purpose Checkpoint inhibitors demonstrate salutary anti-cancer effects including long-term remissions. PD-L1 expression/amplification, high mutational burden and mismatch repair-deficiency correlate with response. We have, however, observed a subset of patients who appear to be “hyper-progressors,” with a greatly accelerated rate of tumor growth and clinical deterioration compared to pre-therapy, which was also recently reported by Institut Gustave Roussy. The current study investigated potential genomic markers associated with “hyper-progression” after immunotherapy. Method Consecutive stage IV cancer patients who received immunotherapies (CTLA-4, PD-1/PD-L1 inhibitors or other [investigational] agents) and had their tumor evaluated by next-generation sequencing were analyzed (N=155). We defined hyper-progression as time-to-treatment failure (TTF) <2 months, >50% increase in tumor burden compared to pre-immunotherapy imaging, and >2-fold increase in progression pace. Results Amongst 155 patients, TTF <2 months was seen in all six individuals with MDM2/MDM4 amplification. After anti-PD1/PDL1 monotherapy, four of these patients showed remarkable increases in existing tumor size (55% to 258%), new large masses, and significantly accelerated progression pace (2.3-, 7.1-, 7.2- and 42.3-fold compared to the two months before immunotherapy). In multivariate analysis, MDM2/MDM4 and EGFR alterations correlated with TTF<2 months. Two of 10 patients with EGFR alterations were also hyper-progressors (53.6% and 125% increase in tumor size; 35.7- and 41.7-fold increase). Conclusion Some patients with MDM2 family amplification or EGFR aberrations had poor clinical outcome and significantly increased rate of tumor growth after single-agent checkpoint (PD-1/PD-L1) inhibitors. Genomic profiles may help to identify patients at risk for progression on immunotherapy. Further investigation is urgently needed.

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The immune-modulating effects of radiation therapy have gained considerable interest recently and there have been multiple reports of synergy between radiation and immunotherapy. However, additional pre-clinical studies are needed to demonstrate the antigen-specific nature of radiation-induced immune responses and elucidate potential mechanisms of synergy with immunotherapy. Here we demonstrate the ability of stereotactic radiotherapy to induce endogenous antigen-specific immune responses when combined with anti-PD-1 checkpoint blockade immunotherapy. Using the small animal radiation research platform (SARRP), image-guided stereotactic radiotherapy delivered to B16-OVA melanoma or 4T1-HA breast carcinoma tumors resulted in the development of antigen-specific T and B cell-mediated immune responses. These immune-stimulating effects of radiotherapy were significantly increased when combined with either anti-PD-1 therapy or regulatory T cell (Treg) depletion, resulting in improved local tumor control. Phenotypic analyses of antigen-specific CD8 T cells revealed that radiotherapy increased the percentage of antigen-experienced T cells and effector memory T cells. Mechanistically we found that radiotherapy up-regulates tumor-associated antigen-MHC complexes, enhances antigen cross-presentation in the draining lymph node, and increased T-cell infiltration into tumors. These findings demonstrate the ability of radiotherapy to prime an endogenous antigen-specific immune response and provide additional mechanistic rationale for combining radiation with PD-1 blockade in the clinic.