New and Worsening Long-term Immune-Related Adverse Events with PD-1/PD-L1 Pathway Agents in Patients with Cancer.

Abstract

Immune checkpoint inhibitors have produced durable responses across a variety of cancers. Although programmed cell death protein 1 (PD-1) and its ligand (PD-L1) inhibitors activate T cells against tumor cells, they may also cause autoimmune-like toxicities termed immune-related adverse events (irAEs). Although much is known regarding irAEs that occur early during treatment, data on the long-term toxicity profile of these agents are more limited. Our primary objective was to evaluate the frequency of patients receiving anti-PD-1/PD-L1 therapy for at least 6 continuous months who experienced new or worsening irAEs requiring clinical interventions. Secondary objectives included assessment of other factors associated with clinically significant irAEs after at least 6months of therapy. Retrospective chart review. Large university-affiliated National Cancer Institute-designated comprehensive cancer center. A total of 159 adults diagnosed with any malignancy who received a PD-1/PD-L1 inhibitor-nivolumab, pembrolizumab, or atezolizumab-as monotherapy or with concurrent cytotoxic agents, for at least 6months, between January 1, 2014, and September 1, 2017. We collected information on the incidence and timing of irAEs, along with patient demographics and other treatment outcomes. Thirty-eight patients (24%) experienced clinically significant, new, or worsening irAEs after 6months of treatment with anti-PD-1/PD-L1 therapy. Hypothyroidism was the most common irAE experienced (20 patients [12.6%]), followed by pneumonitis (5 patients [3%]); 2 patients died due to pneumonitis. Four patients (2.5%) had a deepened disease response beyond 6months of treatment. Our results revealed that a significant proportion of patients continue to experience irAEs with long-term use of PD-1/PD-L1 inhibitors. These results further contribute to the risk-benefit understanding of chronic PD-1/PD-L1 antagonism and support discontinuation of these agents following deepest response.