Arguably the most impactful readout in skin cancer in recent months was MSD and Moderna’s melanoma cancer vaccine data.
At the European Society of Medical Oncology (ESMO) Congress 2026, which took place from 23-27 October in Madrid, Spain, the INTerpath-001 (NCT05933577) data received a standing ovation during the first Presidential Symposium of the conference.
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The data, which was revealed two days early on 22 October by the companies after an embargo breach, showed a 42% reduction in the risk of death or recurrence in the patients who received intismeran autogene plus Keytruda (pembrolizumab) compared with those who received Keytruda alone after 24.6 months. The study enrolled patients with completely resected stage IIB-IV melanoma.
In other sessions, there were several data presentations for other skin cancer studies.
Regeneron presents longer-term C-POST data
This included a Phase III readout from Regeneron Pharmaceuticals of its PD-1 inhibitor Libtayo (cemiplimab) as adjuvant treatment for patients with cutaneous squamous cell carcinoma (CSCC) at a high risk of recurrence after surgery and radiation. CSCC is the second most common skin cancer.
In the Phase III C-POST trial, at a 44-month average follow-up, there was a 37% reduction in the risk of death, up from 22% at a median follow-up of 30 months and 14% at a median follow-up of 24 months.
Notably, patients randomised to placebo were able to cross over to Libtayo after recurrence, and 61 of 69 placebo patients (88%) with recurrence received subsequent Libtayo.
The emerging overall survival (OS) benefit, despite the high crossover rate, therefore, supports treating high-risk patients with Libtayo after surgery and radiation, rather than waiting for their disease to recur.
An exploratory analysis of patients with baseline circulating tumour DNA (ctDNA) data was conducted. When evaluating patients by ctDNA, also known as minimum residual disease (MRD), benefit for disease-free survival (DFS) was significant, regardless of positive or negative MRD. The hazard ratio in MRD-positive patients was 0.24, and in MRD-negative patients, it was 0.45.
Speaking with Clinical Trials Arena, Dr Israel Lowy, PhD, senior VP, clinical development unit head, oncology, at Regeneron, said that this means that if MRD tests are not sensitive enough, patients will still see benefit.
“It could come back MRD negative but have only missed a trace amount. With this drug, regardless of whether you were MRD positive or not, you benefited from taking the treatment,” he said.
Lowy added that, given the positive data for its use following radiation, it would also be interesting to see what a monotherapy trial could show.
“Whether you could achieve this just by using Libtayo alone, it would be interesting to see a study like that,” Lowy said. “It is worth considering because six weeks of radiation is burdensome to patients and can cause toxicities.”
Safety results remained consistent with previously reported data. Treatment-emergent adverse events (TEAEs) of any grade occurred in 94% of patients in the Libtayo arm and 91% of patients in the placebo arm, with Grade ≥3 TEAEs occurring in 26% of patients and 17% of patients in the same arms, respectively.
Treatment discontinuations due to TEAEs occurred in 10% of patients in the Libtayo cohort and 3% of patients in the placebo cohort. TEAEs leading to death occurred in 2% of patients in each arm.
Libtayo was approved by the US Food and Drug Administration (FDA) in October 2025 and the European Commission in November 2025 as the first and only immunotherapy for this indication based on earlier C-POST data.
STARBOARD safety data raises concerns
Final analysis results of Pfizer’s STARBOARD trial (NCT04657991) have demonstrated a meaningful, highly statistically significant clinical benefit with a Keytruda (pembrolizumab) triplet regimen versus standard dual therapy in patients with unresectable locally advanced or metastatic melanoma.
For patients with BRAF V600-mutant metastatic melanoma, the current first-line standard of care is ICIs or other immunotherapy combinations, often without BRAF or MEK inhibitors.
The STARBOARD study met both the primary and key secondary endpoints. The confirmed objective response rate (ORR), the trial’s primary endpoint, was 70.0% in the triplet arm of Keytruda plus Braftovi (encorafenib) and Mektovi (binimetinib) compared with 32.7% in the control arm of Keytruda plus placebo.
Median progression-free survival (PFS) was also significantly extended with the triplet regimen, at 33.0 months compared to 3.4 months, respectively, resulting in a 67% reduction in the risk of disease progression or death.
“The improved PFS from combined use of immunotherapy and targeted therapy as first-line treatment is great to see, but this strategy ‘burns two bullets’ that could be used sequentially if needed as later-line therapy, so it will be important to know whether the significantly extended PFS translates into prolonged OS,” cautions Dr Olivier Michielin from Geneva University Hospital, Switzerland, noting that OS data were immature at data cut-off, while a positive trend towards improved OS was observed in the triplet arm.
Despite impressive ORR and PFS benefits in the STARBOARD experimental arm, “Presented data showed the added toxicity of treatment intensification, although the most common adverse events such as nausea, diarrhoea, vomiting, fatigue and elevated liver enzymes are known toxicities that we have experience in managing,” Michielin added.
Grade 3–4 TEAEs were reported in 70.0% of patients in the STARBOARD triplet arm versus 39.1% of those in the control arm.
