Abstract

Checkpoint inhibitors (CPIs), such as nivolumab, have transformed the treatment paradigm for patients with metastatic non‑small cell lung cancer (mNSCLC) and metastatic renal cell carcinoma (mRCC). The combination of CPIs and radiotherapy (RT) constitutes a multimodal treatment approach that may work synergistically and facilitate augmented systemic responses. The aim of the present retrospective study was to assess the efficacy and safety of continuation of nivolumab treatment with the addition of RT in patients with mNSCLC and mRCC who develop oligometastatic disease progression on single‑agent nivolumab. All patients with mNSCLC and mRCC who received nivolumab at the Department of Oncology, Prince Sultan Military Medical City (Riyadh, Saudi Arabia) between November 2016 and April 2018 were identified. The records of patients who developed oligometastatic disease progression during nivolumab treatment and were subsequently treated with RT, with nivolumab continued beyond disease progression, were retrospectively reviewed. Details of RT, clinical outcomes and toxicity data were collected. Of the 96 patients who received nivolumab, 22 received multiple courses of RT. A total of 39 sites were irradiated: Bone (n=15), lung (n=9), brain (n=8), adrenal gland (n=2), renal bed (n=2), skin (n=1), ethmoid sinus (n=1) and scalp (n=1). Partial response and complete response were noted at 25 (64%) and 3 (8%) sites, respectively. Stable disease was noted at 6 sites (15%) and disease progression was noted at 5 sites (13%). The median time on nivolumab from the date of the first fraction of RT was 4.5 months (range, 1.5‑29 months) for patients with mNSCLC and 5 months (range, 1‑38.5 months) for patients with mRCC. No patients developed grade 3‑4 toxicities. Grade 2 pneumonitis was noted in 3 patients receiving lung RT. The addition of RT appeared to initiate a response and prolong the duration of nivolumab treatment. Therefore, the combination of nivolumab and RT was found to be well tolerated, with response rates exceeding those in published studies of nivolumab monotherapy.