Immune-related adverse events after ≥12 months of starting immune checkpoint inhibitors.

person Agne Jovaisaite Barts Cancer Institute, London, London, United Kingdom info_outline Agne Jovaisaite, Marina Serrano, Francesca Jackson-Spence, Matthew Young, Charlotte Toms, Yishen Wang, Elizabeth Nally, Bernadett Szabados, Thomas Powles

Authors person Agne Jovaisaite Barts Cancer Institute, London, London, United Kingdom info_outline Agne Jovaisaite, Marina Serrano, Francesca Jackson-Spence, Matthew Young, Charlotte Toms, Yishen Wang, Elizabeth Nally, Bernadett Szabados, Thomas Powles Organizations Barts Cancer Institute, London, London, United Kingdom, Barts Cancer Centre, Queen Mary University of London, London, London, United Kingdom, Barts Cancer Institute, London, United Kingdom, Barts Cancer Centre, Queen Mary University of London, London, United Kingdom, Barts Health NHS Trust, London, United Kingdom, St Bart's Hospital, London, United Kingdom, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom, Barts Cancer Centre at St. Bartholomew's Hospital, London, United Kingdom Abstract Disclosures Research Funding No funding received None. Background: Immune checkpoint inhibitors (ICIs) are well established in the treatment of metastatic renal cell (mRCC) and urothelial carcinomas (mUC). The profile of ICI immune-related adverse events (irAEs) is well described, however, data on timings of toxicity and irAEs occurring at ≥12 months are lacking. Methods: A single-site retrospective audit of mRCC and mUC patients receiving ICI-based therapy for ≥12 months between January 2014 and December 2022. ICI-based therapies included monotherapy and combination therapy with other ICIs or anti-VEGF tyrosine kinase inhibitors (TKIs). Best response to ICI-based therapy and irAEs were described. Results: 199 patients received ICI-based therapy, of which 34% (68/199) received treatment for ≥12 months. Of those on therapy for ≥12 months, 44% (30/68), 25% (17/68), and 31% (21/68) were treated with ICI monotherapy, combination with other ICIs, and TKIs, respectively. At data cut-off, 69% (47/68) were alive. 26% (18/68), 59% (40/68) and 15% (10/68) achieved complete response (CR), partial response (PR) and stable disease (SD), respectively. Overall, 83 irAEs were observed in 74% (50/68) of patients receiving therapy for ≥12 months. Of these, 71% (59/83) occurred at < 12 months and 28% (24/85) at ≥12 months. Corticosteroid therapy was required in 31% (18/59) of irAEs at < 12 months and 63% (15/24) at ≥12 months. Endocrine and cutaneous irAEs mostly occurred at < 12 months, while rheumatic irAEs were more frequently observed at ≥12 months. No ICI-related deaths occurred. At ≥12 months, 71% (17/24) of irAEs were grade 1/2 and 29% (7/24) were grade 3/4. Grade ≥3 irAEs at ≥12 months included colitis (n = 1), proctitis (n = 1), tubulointerstitial nephritis (n = 1), bullous pemphigoid (n = 1) and transaminitis (n = 3). Four patients discontinued treatment, the remainder restarted therapy after irAE resolution. All patients with late-onset grade ≥3 irAEs responded to therapy (CR in 2/7, PR in 5/7). A patient with grade 2 seronegative inflammatory arthritis with onset at ≥12 months also discontinued treatment. Conclusions: Although irAEs are less frequent after 12 months of ICI-based therapy, they remain clinically relevant requiring treatment interruption and discontinuation. Patients require ongoing safety monitoring irrespective of the duration of ICI-based therapy.