74P - Real-world impact of adjuvant anti-PD-1 therapy on survival in Danish resected stage III melanoma patients

Background

Adjuvant immunotherapy has been widely implemented for resected stage III melanoma since 2018. However, its impact on overall survival (OS) and melanoma-specific survival (MSS) remains uncertain. OS and MSS data from pivotal phase III trials of adjuvant anti-PD-1 therapy vs placebo has yet to be reported. Here, we present OS and MSS data from a national population-based cohort diagnosed with stage III melanoma before and after the introduction of adjuvant therapy.

Methods

Data were obtained from national Danish registries. The study cohort consisted of patients diagnosed with first-time, resectable stage III melanoma before and after the introduction of adjuvant anti-PD-1 therapy (November 2018), covering January 2016 to June 2018 (pre-cohort) and January 2019 to December 2020 (post-cohort). Patients were followed until August 12, 2024. Propensity score matching (PSM) was used to adjust for baseline characteristics (sex, age, AJCC8 stage and Charlson Comorbidity Index).

Results

475 and 567 patients were included in the pre- and post-cohort, respectively. In the post-cohort, 306 (54%) patients received anti-PD-1 therapy (adjuvant cohort) and 4 (0.7%) received BRAF/MEK inhibitors as adjuvant treatment. No differences in later first-line metastatic therapies were observed between the cohorts not receiving adjuvant therapy. Median follow-up was 87 months for the pre-cohort and 55 months for the post-cohort. In the post- vs. pre-cohort, the 4-year OS was 78.9% and 77.5% (HR 0.86, 95% CI 0.68-1.1, P=0.24) and the 4-year MSS was 85.1% and 83.4% (HR 0.83, 95% CI 0.62-1.12, P=0.223). In a subanalysis of the adjuvant cohort vs. pre-cohort, after PSM (n=306 in each), the HR for OS was 0.65 (95% CI 0.47-0.91, P=0.012), while the HR for MSS was 0.70 (95% CI 0.48-1.02, P=0.063).

Conclusions

This is the longest observation of real-world patients with stage III melanoma in the modern era of adjuvant immunotherapy. Comparison of survival curves after PSM cannot exclude a survival benefit of adjuvant anti-PD-1 therapy in the long run.

Legal entity responsible for the study

The authors.

Funding

Danish Cancer Society Copenhagen University Hospital, Herlev and Gentofte, Herlev Dansk Kræftforskningsfond Lizzi og Mogens Staal Fonden Køben Kjær Født la Cour-holmes Fond Marie og Børge Kroghs Fond.

Disclosure

M.B. Weitemeyer: Financial Interests, Personal and Institutional, Research Funding, Funding to conduct a descriptive report of stage II/III melanoma patients in DK, covering my salary: MSD DK; Financial Interests, Personal, Speaker, Consultant, Advisor, Oral presentation of descriptive data on Danish stage II/III melanoma at an advisory board meeting: MSD DK. M. Donia: Financial Interests, Personal, Other, Advisor: Achilles Therapeutics; Financial Interests, Personal, Other, Advisor (not for pharmaceutical companies): Guidepoint Global LLC, Alphasights; Other, Personal, Other, Chairman of the Melanoma and Non-melanoma Skin Cancer Scientific Committee: Danish Medicines Council (Medicinrådet). N.M. Helvind: Financial Interests, Personal, Speaker, Consultant, Advisor, Speaker: MSD DK. L. Bastholt: Non-Financial Interests, Personal, Advisory Role, Scientific committee under Danish Medicines Agency regarding new treatments of melanoma, skin cancer and thyroid cancer; Danish Medicines Agency. I.M. Svane: Financial Interests, Personal, Advisory Board: Novartis, Mendus, Instil Bio; Financial Interests, Personal, Invited Speaker: MSD, BMS, Sanofi, Takeda; Financial Interests, Personal, Writing Engagement: MSD; Financial Interests, Personal, Stocks/Shares, Cofounder and Founder warrants: IO Biotech; Financial Interests, Institutional, Research Grant: Adaptimmune, Enara Bio, Lytix Biopharma, TILT Biotherapeutics, Asgard Therapeutics, IO Biotech; Financial Interests, Institutional, Funding: Evaxion; Financial Interests, Institutional, Other, drug for investigator driven trial: BMS; Non-Financial Interests, Personal, Principal Investigator: BMS, Roche, TILT Biotherapeutics, Lytix Biopharma, Novartis, Immunocore, MSD. L. Rosenkrantz Hölmich: Other, Institutional, Research Funding, Funding to conduct a descriptive report of stage II/III melanoma patients in DK: MSD DK. E. Ellebaek: Financial Interests, Personal, Invited Speaker: Pierre Fabre, BMS, Novartis, MSD, Pfizer; Other, Personal, Other, Travel and conference expenses: MSD, Pierre Fabre. All other authors have declared no conflicts of interest.