e15078

Background: Checkpoint inhibitors (CPIs) such as nivolumab have transformed the treatment paradigm for patients (pts) with metastatic non-small cell lung cancer (mNSCLC) and renal cell carcinoma (mRCC). Low response rates (20%) with CPIs has prompted novel immunotherapy combination trials. Radiotherapy (RT) causes direct tumor cell death and in addition also effectively stimulates T-cell immunity. RT is a highly cost-effective anti-cancer treatment and its combination with CPIs may herald a new potent therapeutic tool. This study reports on the efficacy and toxicity of concurrent nivolumab and RT administration. Methods: Pts with mNSCLC and mRCC receiving concurrent nivolumab and RT were assessed retrospectively for radiological response (RECIST 1.1), toxicity and symptom benefit (pain score). Results: Of the 63 pts that received nivolumab at our institution, 15 pts received concurrent RT for 32 courses; mNSCLC (n = 8), mRCC (n = 7). Median age 59 years (range 39-71); M:F ratio (4:1). Stereotactic and conformal RT was delivered to 5 and 27 sites, respectively. Most common indication for RT was oligometastatic disease progression (PD): 59%. Treatment sites included: bones (n = 13), lung (n = 7), brain (n = 5), adrenal, renal bed, skin, ethmoid and scalp. The gap between RT & nivolumab did not exceed 2 weeks for all patients. No grade 3-4 toxicities were observed; grade 2 pneumonitis noted in 2 pts. Fractionation schedules included 20Gy/5 fractions (#) (most common-47%), 48Gy/4#, 40Gy/10#, 40Gy/4#, 34Gy/4#, 30Gy/10#, 25Gy/5#, 20Gy/4#, 16Gy/4#, 22Gy/1# and 8Gy/1#. Of the 23 measurable sites, 70% had excellent response including complete response at 3 sites. Pain scores improved in 6 out of 9 sites (67%). Conclusions:The combination of nivolumab and RT appears to be well tolerated in pts with mNSCLC and mRCC with response rates exceeding published studies of nivolumab monotherapy. For patients with oligometastatic PD during nivolumab therapy, addition of RT appears to initiate a response and prolong time spent on nivolumab. Future clinical trials may better define whether RT during nivolumab treatment should be used as induction therapy, consolidative therapy or should be used for pts with oligometastatic PD.