REPL’s RP1 plus Nivolumab Delivers 44% Response Rate in Acral Melanoma—Rare Disease Sees Hope at ESMO 2025

IGNYTE Trial Reveals a Meaningful Objective Response Rate in Challenging Patient Group

New data presented at the ESMO Congress 2025 put Replimune (NASDAQ: REPL) squarely in the spotlight for its progress in a notoriously difficult cancer—acral melanoma. In the phase 2 IGNYTE cohort, patients with this rare skin cancer saw an objective response rate (ORR) of 44% with the combination of RP1 and nivolumab. That’s 8 out of 18 participants seeing their tumors shrink significantly, with the median duration of those responses lasting nearly a year (11.9 months), and the upper bound not yet reached at the time of reporting.

Acral Melanoma: Rare, Aggressive, and Tough to Treat

Why is this noteworthy? Acral melanoma makes up just 2-3% of all melanoma cases, most often affecting the palms, soles, and nailbeds. Historically, outcomes for this group have been poor—immune checkpoint inhibitors, the mainstays for advanced melanoma, usually have little effect here. After failing first-line therapy, there are almost no effective treatments except for a limited subset of BRAF-mutant patients who qualify for targeted therapies.

Clinical Outcomes: Promising Response and Manageable Safety

Safety results further strengthen the case: the majority of adverse events were grade 1 or 2 and short-lived—reassuring news in an aggressive disease where tolerability can often dictate real-world success.

Pipeline Momentum: IGNYTE-3 and Expanded Trials

The momentum doesn’t stop at phase 2. Replimune is already enrolling patients in the IGNYTE-3 randomized phase 3 trial, where RP1 plus nivolumab will be compared against physicians’ choice in patients who have already failed both anti-PD1 and anti-CTLA-4 therapies. This is a patient segment that typically faces dismal odds.

RP1’s Platform: An Engineered Oncolytic Virus Strategy

RP1, Replimune’s flagship therapy, is based on an engineered herpes simplex virus, turbocharged with genetic additions designed to maximize immune system activation against tumors. The platform’s design aims for synergistic effects when paired with checkpoint inhibitors, with a broader ambition to tackle cancers resistant to standard immunotherapy approaches.

Takeaway: Durable Benefit in a Difficult Melanoma Subtype

For investors, physicians, and patients alike, this update offers new optimism for a previously hard-to-treat population. With an ORR of 44% and median response exceeding 11 months, the RP1 plus nivolumab regimen could become a major advance—if these results hold up in the upcoming phase 3 trial.

While uncertainties remain—as is common with early- and mid-stage trial data—this signal stands out for its relevance and potential. Anyone tracking the next breakthroughs in oncology may want to keep a close eye on REPL’s evolving clinical story.

Contact Information:

If you have feedback or concerns about the content, please feel free to reach out to us via email at support@marketchameleon.com.

About the Publisher - Marketchameleon.com:

Marketchameleon is a comprehensive financial research and analysis website specializing in stock and options markets. We leverage extensive data, models, and analytics to provide valuable insights into these markets. Our primary goal is to assist traders in identifying potential market developments and assessing potential risks and rewards.

NOTE: Stock and option trading involves risk that may not be suitable for all investors. Examples contained within this report are simulated and may have limitations. Average returns and occurrences are calculated from snapshots of market mid-point prices and were not actually executed, so they do not reflect actual trades, fees, or execution costs. This report is for informational purposes only, and is not intended to be a recommendation to buy or sell any security. Neither Market Chameleon nor any other party makes warranties regarding results from its usage. Past performance does not guarantee future results. Please consult a financial advisor before executing any trades. You can read more about option risks and characteristics at theocc.com.

The information is provided for informational purposes only and should not be construed as investment advice. All stock price information is provided and transmitted as received from independent third-party data sources. The Information should only be used as a starting point for doing additional independent research in order to allow you to form your own opinion regarding investments and trading strategies. The Company does not guarantee the accuracy, completeness or timeliness of the Information.

Disclosure: This article was generated with the assistance of AI