A large retrospective study published in JAMA Network Open reveals that chronic immune-related adverse events (irAEs) are surprisingly common — and persistent — among melanoma patients receiving adjuvant anti-PD-1 therapy. Of 303 patients with resected stage III–IV melanoma, 73% developed acute irAEs and nearly half (48%) went on to develop chronic irAEs, defined as lasting at least 3 months after stopping treatment. At a median follow-up of 67 months, 34% still had ongoing symptoms.

The research also highlights a nuanced relationship between corticosteroid use and chronic irAE risk. When irAEs appeared within the first 42 days of treatment, patients treated with corticosteroids were three times more likely to develop chronic irAEs compared to those who weren't. That risk diminished significantly when irAE onset occurred later (around 259 days). On the molecular side, 8 cytokines — including FGF-23, MMP-1, and VEGFA — were significantly elevated in patients with chronic irAEs, suggesting a potential biological hallmark of the condition.

By the Numbers:

• 73% of patients developed acute irAEs
• 48% developed chronic irAEs (lasting ≥3 months post-treatment)
• 34% still had ongoing chronic irAEs at median 67-month follow-up
• Corticosteroid use with early irAE onset (≤42 days): adjusted OR 3.00 for chronic irAE development
• 8 out of 92 cytokines were significantly upregulated in chronic irAE patients

Why it matters: As more melanoma patients achieve long-term survival on anti-PD-1 therapy, managing lasting side effects becomes critical. This study signals that clinicians should weigh corticosteroid use carefully — particularly early in treatment — and that cytokine profiling could one day help flag patients at highest risk before chronic damage sets in.