Effect of Administration of Systemic Steroids on Survival Benefit Associated with Immunotherapy-Induced Skin Toxicity.

e22046 Background: Immune checkpoint inhibition (ICI) improves progression-free survival (PFS) and overall survival (OS) for patients with metastatic melanoma (MM), but treatment may cause serious immune-related adverse events (irAEs) that require the use of immunosuppressive steroids. Skin toxicity (ST), the most common side effect, has been reported to be associated with better response to ICI in some studies but not others. Herein, we tested the hypothesis that the portended survival benefit associated with ICI-related ST reaches a threshold in MM patients, dependent on the severity of the ST. Methods: We analyzed MM patients enrolled prospectively in a clinicopathological database with protocol-driven follow up and treated with ICI at NYULH. The patient and/or physician reported the ST, and an immunologist-dermatologist independently confirmed the event was ICI-related. Severe ST was defined as a skin event that required treatment with systemic steroids. Other site-specific toxicities were recorded using the CTCAE v5.0. We tested the associations between ST and PFS and OS, stratified by no, mild, and severe ST, adjusting for age, gender, number of metastatic sites, LDH, and ECOG score at treatment initiation. Results: The cohort included 256 MM patients (387 lines of ICI treatments). ST was the most common irAE (34%), and was significantly associated with development of endocrine toxicity (P = 0.007). Of the ST events (n = 130), 66% were mild and 34% were severe. Compared to none, mild ST was significantly associated with improved PFS (adjusted hazard ratio [aHR] = 0.58 [0.38, 0.89], P = 0.01), and a similar trend was observed with OS (aHR = 0.68 [0.45, 1.03], P = 0.06). However, the positive effect was reduced to insignificant (PFS P = 0.53; OS P = 0.25) in patients who developed severe ST irAEs that required systemic steroids. Conclusions: Our data demonstrate that ICI-induced ST is a complex phenomenon and might explain the discordance of reported data. While the worse outcome in patients with severe ST compared to mild may stem from steroidal immunosuppression, a threshold may also exist wherein severe ST itself might contribute to a relative reduction in ICI efficacy. More research is needed to elucidate the mechanisms that link ST and response to ICI in order to better characterize and treat skin irAEs without systemically suppressing anti-tumor immunity.