ESMO Congress 2026

Melanoma is one of the tumor types with the deepest accumulated immunotherapy evidence. In a phase 3 study enrolling 676 previously treated patients with unresectable stage III/IV melanoma, the CTLA-4 inhibitor ipilimumab combined with the gp100 peptide vaccine improved median overall survival to 10.0 months versus 6.4 months with gp100 alone ^[3]; the PD-1 antibody BMS-936558 subsequently showed objective responses in advanced solid tumors including melanoma ^[4]. On the demand side, U.S. melanoma incidence continued to rise by about 2%-3% annually during 2015-2019 ^[6], keeping recurrence-prevention strategies a persistent unmet treatment need for post-surgical populations.

The main storyline reported at this year's ESMO26 in Madrid is a trial of a personalized cancer vaccine designed to prevent post-surgical recurrence: adding a vaccine tailored to each patient on top of standard immunotherapy reduced the risk of melanoma coming back by 42% versus immunotherapy alone. Dr. Michael Postow, Chief of the Melanoma Service at MSK, explained the logic: by specifically boosting a patient's immune system to recognize their own tumor cells, the risk of recurrence can be reduced; even when no cancer is visible on CT or PET scans, a high proportion of patients eventually recur, hence the tremendous need for this type of treatment. The post also links the story of one of the three MSK patients treated in the trial. A second item in the same batch of posts: Toni Ribas received the ESMO'26 award, summarizing that immunotherapy has progressed from responses in only 1 of 20 patients to responses in more than half of advanced cases, and that the next big advance will be understanding why some patients do not respond and how to overcome resistance.

Unlike the existing evidence, which was mainly generated in advanced and metastatic populations (^[3] enrolled previously treated metastatic disease and ^[4] advanced solid tumors), this readout moves the immunotherapy strategy earlier into the post-surgical adjuvant setting, targeting patients with no radiographic disease but possible residual disease, with recurrence risk as the efficacy measure; moreover, unlike the gp100 peptide vaccine of the ^[3] era, the current vaccine is personalized to each patient and combined with standard immunotherapy, extending the checkpoint inhibitor evidence chain within the same tumor type toward earlier disease.

As for limitations, the post discloses no trial name, phase, sample size, follow-up duration, or overall survival data; the 42% is a relative recurrence risk reduction figure circulated at the social media level; Ribas's more than half responding is an award-speech-style summary rather than a specific trial readout — all await confirmation once formal data are published.