Conditional Survival Improves Over Time in Advanced Melanoma Treated With ICI

Prognosis was enhanced with conditional survival for patients with advanced melanoma who were progression-free after immune checkpoint inhibitor (ICI) therapy, according to a poster presented at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting and Exposition^.

The 5-year progression-free survival (PFS) was 29% (95% CI, 26%–33%), the 5-year overall survival (OS) was 39% (95% CI, 36%–43%), and the 5-year melanoma-specific survival (MSS) was 48% (95% CI, 45%–52%). Conditional survival analysis revealed striking improvements with each additional year of progression-free status. For all patients, the conditional 5-year PFS probability increased from 0.29 (95% CI, 0.26–0.33) at year 0 to 0.59 (95% CI, 0.53–0.63) at year 1 in complete, 0.73 (95% CI, 0.67–0.78) at year 2, 0.82 (95% CI, 0.77–0.86) at year 3, and 0.91 (95% CI, 0.86–0.95) at year 4.

Patients who achieved a complete response (n = 245; 27.4%) demonstrated the most favorable conditional PFS trajectory, with estimates rising from 0.74 at year 0 to 0.92 at year 4. Those treated with combination anti–PD-1 plus anti–CTLA-4 therapy saw conditional 5-year PFS improve from 0.38 at year 0 to 0.94 at year 4. Even patients with baseline ECOG performance status of at least 2, who began with a conditional 5-year PFS of 0.16, saw this estimate improve to 0.91 by year 4, converging toward the broader cohort among those who remained progression-free. Across subgroups defined by lactate dehydrogenase level, site of metastases, BRAF mutation status, and treatment regimen, patients who survived longer without progression showed consistent and marked improvements in future survival estimates.

Long-term survivors also approached mortality rates comparable with those of the general population. Among patients alive 5 years after ICI, the standard mortality rate (SMR) was 1.35 (95% CI, 0.87–1.99; P = .166); among patients who were progression-free for 3 years, the SMR was 1.22 (95% CI, 0.88–1.65; P = .217). Neither was statistically significantly different from the matched population, suggesting normalization of mortality risk in durable responders.

“Conditional survival illustrates dynamic improvement in prognosis for patients with advanced melanoma who remain progression-free following ICI therapy, with long-term survivors approaching normalized mortality of the matched general population,” wrote lead study author Chloe A. Lim, MD, of BC Cancer Agency in Vancouver, British Columbia, Canada.

The study enrolled adults with unresectable or metastatic cutaneous melanoma who received at least 1 dose of a PD-1–based ICI between 2012 and 2022 at BC Cancer Agency sites in British Columbia, Canada, with follow-up through December 2025. The cohort (n = 897) was predominantly male (64.9%), with a median age at treatment initiation of 69 years (IQR, 61–77). Most patients had an ECOG performance status of 0 to 1 (83.3%), and approximately half presented with M1c/M1d disease (48.9%). High-risk features were prevalent: 29.5% had elevated LDH, 34.9% had brain metastases at baseline, and 39.3% harbored a BRAF mutation. ICI regimens included PD-1 monotherapy in 67.7% of patients and combined PD-1 plus CTLA-4 therapy in 32.3%. Grade 3/4 immune-related adverse events (irAEs) occurred in 25.3% of patients.

End points included PFS, MSS, and OS estimated by Kaplan-Meier analysis, with multivariable Cox regression for OS and Fine-Gray modeling for MSS. Immune-related adverse effects were modeled as a time-dependent covariate to address immortal-time bias. Conditional survival was computed at annual landmarks from year 0 through year 5, stratified by baseline covariates and best overall response. Relative survival was assessed using SMRs compared with age-, sex-, and year-matched British Columbia life table data.

The investigators concluded that conditional survival provides time-updated probabilities that more accurately reflect the evolving prognosis of patients who remain event-free following ICI therapy for advanced melanoma. Unlike traditional fixed survival estimates calculated from treatment initiation, conditional survival improves dynamically as patients accrue progression-free time; this directly informs patient counseling conversations, imaging surveillance frequency, and long-term survivorship planning.

Reference

Lim CA, Nghiem L, Angeles A, et al. Conditional survival in advanced melanoma patients treated with immune checkpoint inhibitors. J Clin Oncol. 2026;44(suppl 16):12108. doi:10.1200/JCO.2026.44.16_suppl.12108