Personalized mRNA Therapy Cut Melanoma Recurrence by 42%: INTerpath-001 Results at ESMO 2026
In this article
INTerpath-001: Does personalized mRNA therapy (intismeran) reduce melanoma recurrence after surgery?
Medical content reviewed by Prof. Dr. Mustafa Özdoğan · Last updated: October 2026
The INTerpath-001 phase 3 trial, presented at ESMO 2026 Presidential Symposium I, showed that adding the personalized mRNA therapy intismeran to pembrolizumab reduced the risk of recurrence or death by 42% (HR 0.58) after complete surgical removal of stage IIB–IV melanoma. Overall survival data are not yet mature, and the therapy is not approved in any country.
- Primary endpoint (recurrence-free survival): HR 0.58 (95% CI 0.45–0.75; p<0.001). At 24 months, 82.2% vs 70.0% were recurrence-free: an absolute difference of 12.2 points, or roughly one recurrence (or death) avoided for every 8 patients.
- Distant metastasis-free survival: HR 0.62 (95% CI 0.45–0.85); 88.5% vs 80.2% at 24 months (8.3-point difference).
- Timing: No difference in the first 6 months (HR 0.99); HR 0.42 after the intismeran course. This is a prespecified sensitivity analysis; the main result is HR 0.58.
- Limits: Median follow-up 24.6 months; overall survival is not significant (HR 0.77; 95% CI 0.45–1.31). The therapy is investigational; side effects were mostly low-grade fever, injection-site pain and fatigue.
Why does this matter?
Even after complete surgical removal of high-risk melanoma, the disease returns in a proportion of patients. Recurrence most often occurs within the first two years, and more than half of patients who relapse develop distant metastases in organs such as the lung, liver or brain (Merck statement). The goal of post-operative (adjuvant) treatment is therefore to prevent or delay recurrence. Adjuvant immunotherapy with pembrolizumab is already a standard option in stage IIB, IIC and III melanoma (KEYNOTE-054, KEYNOTE-716).
According to the companies, INTerpath-001 is the first positive phase 3 result for an individualized neoantigen therapy and for an mRNA-based cancer therapy. In the phase 2b KEYNOTE-942 trial, the 5-year recurrence-free survival HR was 0.51; the phase 3 trial showed a benefit in the same direction in a much larger population. This does not mean the therapy is ready for routine use: Merck and Moderna are engaging with regulators, but there is no approval yet and overall survival data are awaited.
How does intismeran (personalized mRNA therapy) work in melanoma?
Intismeran is an mRNA therapy built from the mutations in a patient's own tumor and encoding up to 34 neoantigens. It aims to help the immune system recognize tumor cells. Each product is designed individually from tumor and normal DNA sequencing. In INTerpath-001 it was given with pembrolizumab after surgery to reduce recurrence; no survival advantage is shown yet.
How was the INTerpath-001 trial conducted?
INTerpath-001 is a randomized, double-blind, placebo- and active-comparator-controlled phase 3 trial (NCT05933577). Both arms received standard adjuvant pembrolizumab; the difference was whether patients also received intismeran or placebo.
| Feature | Details |
|---|---|
| Patients | 1,137 patients; 2:1 randomization (757 intismeran + pembrolizumab, 380 placebo + pembrolizumab) |
| Disease | Completely resected AJCC 8th edition stage IIB/IIC, III or IV cutaneous melanoma; no prior systemic therapy; surgery no more than 13 weeks before randomization; ocular and mucosal melanoma excluded |
| Other requirements | ECOG performance status 0–1; tumor sample suitable for next-generation sequencing |
| Intismeran | 1 mg intramuscularly every 3 weeks, up to 9 doses |
| Pembrolizumab | 400 mg intravenously every 6 weeks, up to 9 cycles (about 1 year) |
| Primary endpoint | Recurrence-free survival: time from randomization to any recurrence (investigator-assessed) or death from any cause |
| Secondary endpoints | Distant metastasis-free survival, overall survival, safety, quality of life |
| Participants | Median age 61; about 60% male; randomization stratified by risk-based stage and age |
| Follow-up | Median 24.6 months (data cutoff 30 June 2026) |
Figure 1 · How and when was treatment given?
INTerpath-001 trial flow (simplified)
What were the recurrence-free and distant metastasis-free survival results?
All comparisons below are between the two arms of the same trial, so they are direct comparisons. Colored bars are intismeran + pembrolizumab; gray bars are placebo + pembrolizumab.
24-month rates
Recurrence-free and distant metastasis-free survival · ITT and mITT
Recurrence-free survival (RFS) · 24 months
Distant metastasis-free survival (DMFS) · 24 months
RFS · mITT sensitivity analysis · 24 months
HR: RFS 0.58, DMFS 0.62, mITT RFS 0.51. The mITT analysis excludes patients who did not receive at least one planned dose of intismeran/placebo.
| Endpoint | HR (95% CI) | Events (combination / control) | 24-month rate |
|---|---|---|---|
| Recurrence-free survival (primary, ITT) | 0.58 (0.45–0.75); p<0.001 | 136 (18.0%) / 111 (29.2%) | 82.2% / 70.0% |
| Distant metastasis-free survival (ITT) | 0.62 (0.45–0.85); p=0.002 | 89 (11.8%) / 71 (18.7%) | 88.5% / 80.2% |
| Recurrence-free survival (mITT) | 0.51 (0.39–0.67) | – | 84.2% / 70.4% |
| Distant metastasis-free survival (mITT) | 0.55 (0.40–0.77) | – | 90.1% / 80.7% |
| Overall survival | 0.77 (0.45–1.31); p=0.33 | – | Immature |
Median RFS and median DMFS have not been reached in either arm. Endpoints were tested hierarchically (RFS, then DMFS, then overall survival); overall survival did not cross the prespecified significance boundary and follow-up continues.
In which patient groups was a benefit seen?
The benefit pointed in the same direction in most prespecified subgroups. In small subgroups, confidence intervals crossed 1; no firm conclusions can be drawn for those groups.
| Subgroup | RFS HR (95% CI) | DMFS HR (95% CI) |
|---|---|---|
| Stage IIB/IIC/IIIA/IIIB | 0.60 (0.41–0.88) | 0.65 (0.41–1.02) |
| Stage IIIC/IIID/IV | 0.57 (0.41–0.79) | 0.59 (0.39–0.91) |
| Under 65 years | 0.65 (0.47–0.91) | – |
| 65 years and older | 0.53 (0.36–0.77) | – |
In the stage IIB–IIIB subgroup the DMFS confidence interval includes 1. In the US subgroup, the DMFS HR of 1.77 (95% CI 0.38–8.35) is based on only 10 events and is too uncertain to interpret.
Why was there no difference in the first 6 months?
In the trial, pembrolizumab starts at randomization, while intismeran is made for each patient and given once the product is ready. The median time to the first intismeran dose was 64 days. In the first 6 months the curves overlapped (RFS HR 0.99; 95% CI 0.66–1.49; DMFS HR 1.01; 95% CI 0.58–1.79).
After month 6, a prespecified sensitivity analysis gave an RFS HR of 0.42 (95% CI 0.30–0.58) and a DMFS HR of 0.50 (95% CI 0.34–0.73). The companies and investigators interpret this as the benefit emerging once the immune response has developed. However, this is a sensitivity analysis; the HR of 0.58 in the main analysis should be used as the effect size.
What are the most common side effects during treatment?
The safety profile was consistent with previously reported data for intismeran plus pembrolizumab; no new safety signal was reported. Investigators described the added side effects of the combination as low-grade and transient.
Most common adverse events and severe events
Intismeran + pembrolizumab vs placebo + pembrolizumab
Fever (any cause, any grade)
Injection-site pain
Fatigue
Influenza-like illness
Grade 3 or higher event of any cause
Treatment-related grade 3–5 event
Red bars mark severe events in the combination arm that need attention. The comparison is between the two arms of the same trial.
| Measure | Intismeran + pembrolizumab | Placebo + pembrolizumab |
|---|---|---|
| Any treatment-related event | 95.8% | 90.0% |
| Serious treatment-related event | 9.8% | 11.1% |
| Discontinuation of any study drug due to a treatment-related event | 14.0% | 8.7% |
| Discontinuation of both drugs due to an event | 6.5% | 5.3% |
| Immune-mediated events of interest for pembrolizumab | 36.0% | 34.7% |
| Treatment-related loss of life | 2 patients (0.3%); both attributed to pembrolizumab | – |
Intismeran did not increase the immune-mediated side effects associated with pembrolizumab. Treatment completion was similar in the two arms (69.8% vs 69.1%); discontinuation because of recurrence was less frequent in the combination arm (10.8% vs 17.9%). The known immune-mediated side effects of pembrolizumab (thyroid, bowel, liver, lung and others) still need monitoring in both arms.
How is a personalized therapy prepared in practice?
- A tumor sample is required: The patient's tumor and normal DNA are sequenced, and an mRNA encoding up to 34 neoantigens is designed. Of 1,749 patients screened, 302 (17.3%) could not enter the trial because the tumor sample was inadequate.
- Manufacturing largely succeeded: Product was manufactured for more than 99% of patients in the combination arm; the maximum number (34) of neoantigens was identified in 91% of randomized patients.
- There is a preparation time: The median time to the first intismeran dose was 64 days (about 9 weeks); patients received a median of 9 doses.
- Completion rates were similar: Treatment was completed by 69.8% in the combination arm and 69.1% in the pembrolizumab arm.
Which results are established, and which are not yet clear?
Figure 2 · Evidence map
INTerpath-001, ESMO 2026 LBA1
- Approval: Intismeran has not yet been approved by any health authority worldwide; Merck and Moderna state that they are engaging with regulators. It is therefore not available as a licensed therapy.
- Reimbursement: As an unapproved therapy, there is no reimbursement. Coverage for adjuvant pembrolizumab differs by country and insurer and should be checked locally.
- Access: The sources do not mention any access route outside the trial. INTerpath-001 is listed as active but no longer recruiting.
- What should patients do? Post-operative melanoma treatment is planned by a tumor board according to stage, risk and the patient's condition. Discuss the currently available options, including adjuvant pembrolizumab, with your own oncologist.
Frequently asked questions
- Is intismeran a cancer vaccine?
- Intismeran is an mRNA-based individualized neoantigen therapy made from a patient's own tumor and is often called a "personalized cancer vaccine". It does not prevent the disease; it aims to strengthen the immune response against tumor cells that may remain after surgery.
- Is this treatment available now?
- No. Intismeran is not approved in any country. The results have been accepted for publication in the New England Journal of Medicine and the companies are engaging with regulators; the decision and its timing are unknown.
- Did it improve overall survival?
- Not yet shown. Overall survival data are immature and did not reach the significance boundary (HR 0.77; 95% CI 0.45–1.31). Follow-up continues.
- What are the side effects?
- The most common were fever, injection-site pain, fatigue and flu-like symptoms, mostly low-grade and transient. Severe (grade 3–5) treatment-related events were similar in the two arms (14.2% vs 13.4%).
Glossary
- Adjuvant therapy
- Treatment given after surgical removal of the visible tumor to prevent recurrence.
- Recurrence-free survival (RFS)
- Time from randomization to recurrence of disease at any site or death from any cause.
- Distant metastasis-free survival (DMFS)
- Time until spread to distant organs or death.
- Neoantigen
- Protein fragment created by tumor-specific mutations that the immune system can recognize as foreign.
- Hazard ratio (HR)
- A value below 1 means a lower risk of an event (recurrence or death) in the experimental arm; 0.58 means about a 42% lower risk.
- ITT and mITT
- ITT analyzes everyone randomized; mITT is a sensitivity analysis of those who received at least one dose as planned.
DROZDOGAN Academy Commentary
INTerpath-001 is the first randomized phase 3 dataset showing that a personalized mRNA therapy adds recurrence control on top of adjuvant pembrolizumab; a survival benefit has not yet been confirmed.
⚡ Why it matters
Pembrolizumab has been a standard adjuvant option in melanoma for years, and this is the first phase 3 trial to show added benefit on top of it. It also suggests that an individualized approach can work in a large patient population.
✅ Strengths
Randomized, double-blind, placebo-controlled design; 1,137 patients; both the primary and the key secondary endpoint were significant; the mITT analysis and most subgroups pointed the same way; safety shows no marked added burden beyond pembrolizumab's known profile.
⚠️ Limitations
Median follow-up is 24.6 months and overall survival is not significant. The overlapping curves in the first 6 months and the HR of 0.42 afterward come from a sensitivity analysis; the main effect is HR 0.58. The comparator is pembrolizumab alone. The data are company-sponsored and the full text has not yet been reviewed.
🩺 In practice
Because the therapy is not approved, it is not an available option for patients today. Standard adjuvant options after melanoma surgery should continue to be discussed at the tumor board.
❓ Open questions
Will there be an overall survival benefit? In which stages and patients is the benefit greatest? How will inadequate tumor samples (17.3%) and the 64-day preparation time be handled in practice? What about long-term safety, cost and access?
Bottom line: A strong and encouraging phase 3 result for recurrence control; until the effect on survival and the regulatory path are clear, it should be interpreted with caution.
- This article was prepared in October 2026.
- Figures are taken from the Merck/Moderna company statement of 22 October 2026 and from OncLive, CancerNetwork and Targeted Oncology reports on the ESMO 2026 LBA1 presentation (24 October 2026; presenter G. V. Long). The results have been accepted for publication in the New England Journal of Medicine; the full text was not accessible.
- The overall survival HR (0.77), the number of treatment-related deaths, serious event and discontinuation rates and the manufacturing data come from a secondary source (CancerNetwork); the company statement only mentions a favorable trend for overall survival.
- The data come from a company-sponsored (Merck/Moderna) trial. The "first phase 3" wording belongs to the companies and is limited to individualized neoantigen/mRNA-based therapy; other cell-based cancer vaccines have been approved before.
- The abstract was released early on 22 October 2026 after an embargo breach; reports after the presentation are consistent with these data.
- The charts show only direct comparisons between arms of the same trial; the comparison with KEYNOTE-942 (phase 2b) is indirect and is mentioned only for context.
- The figures are derived from verified statements in the text and contain no new data. The Academy commentary is our own.
References
- Merck & Moderna. Merck and Moderna will present results from landmark Phase 3 INTerpath-001 trial of intismeran autogene plus KEYTRUDA at ESMO 2026 Presidential Symposium. News release, 22 Oct 2026. https://www.merck.com/news/merck-and-moderna-will-present-results-from-landmark-phase-3-interpath-001-trial-for-intismeran-autogene-plus-keytruda-pembrolizumab-at-esmo-2026-presidential-symposium/
- Long GV. INTerpath-001: Phase 3 study of intismeran autogene plus pembrolizumab vs pembrolizumab alone for adjuvant treatment of resected stage IIB-IV melanoma. ESMO Congress 2026, Madrid, Presidential Symposium I, LBA1.
- CancerNetwork. INTerpath-001 data detail survival, subgroup, and safety findings in melanoma. 24 Oct 2026. https://www.cancernetwork.com/view/interpath-001-data-detail-survival-subgroup-and-safety-findings-in-melanoma
- Targeted Oncology. Personalized mRNA vaccine intismeran plus pembro cuts melanoma recurrence. 23 Oct 2026. https://www.targetedonc.com/view/personalized-mrna-vaccine-intismeran-autogene-pembrolizumab-cuts-melanoma-recurrence
- OncLive. Intismeran autogene plus pembrolizumab meets RFS and DMFS end points in resected stage IIB-IV melanoma. 19 Aug 2026. https://www.onclive.com/view/intismeran-autogene-plus-pembrolizumab-meets-rfs-dmfs-end-points-in-resected-melanoma
- ClinicalTrials.gov. INTerpath-001 (NCT05933577). https://clinicaltrials.gov/study/NCT05933577
- Carlino MS, Khattak A, Meniawy T, et al. Intismeran autogene plus pembrolizumab in resected melanoma: 5-year update of KEYNOTE-942. J Clin Oncol. 2026;44(suppl 16):9500. https://doi.org/10.1200/JCO.2026.44.16_suppl.9500
- Luke JJ, Ascierto PA, Khattak MA, et al. Pembrolizumab vs placebo as adjuvant therapy in resected stage IIB or IIC melanoma: final analysis of DMFS in KEYNOTE-716. J Clin Oncol. 2024;42(14):1619-1624. https://doi.org/10.1200/JCO.23.02355
- Eggermont AMM, Blank CU, Mandala M, et al. Adjuvant pembrolizumab versus placebo in resected stage III melanoma (KEYNOTE-054). N Engl J Med. 2018;378:1789-1801. https://doi.org/10.1056/NEJMoa1802357
INTerpath-001: Does personalized mRNA therapy (intismeran) reduce melanoma recurrence after surgery?
Medical content reviewed by Prof. Dr. Mustafa Özdoğan · Last updated: October 2026
The INTerpath-001 phase 3 trial, presented at ESMO 2026 Presidential Symposium I, showed that adding the personalized mRNA therapy intismeran to pembrolizumab reduced the risk of recurrence or death by 42% (HR 0.58) after complete surgical removal of stage IIB–IV melanoma. Overall survival data are not yet mature, and the therapy is not approved in any country.
- Primary endpoint (recurrence-free survival): HR 0.58 (95% CI 0.45–0.75; p<0.001). At 24 months, 82.2% vs 70.0% were recurrence-free: an absolute difference of 12.2 points, or roughly one recurrence (or death) avoided for every 8 patients.
- Distant metastasis-free survival: HR 0.62 (95% CI 0.45–0.85); 88.5% vs 80.2% at 24 months (8.3-point difference).
- Timing: No difference in the first 6 months (HR 0.99); HR 0.42 after the intismeran course. This is a prespecified sensitivity analysis; the main result is HR 0.58.
- Limits: Median follow-up 24.6 months; overall survival is not significant (HR 0.77; 95% CI 0.45–1.31). The therapy is investigational; side effects were mostly low-grade fever, injection-site pain and fatigue.
Why does this matter?
Even after complete surgical removal of high-risk melanoma, the disease returns in a proportion of patients. Recurrence most often occurs within the first two years, and more than half of patients who relapse develop distant metastases in organs such as the lung, liver or brain (Merck statement). The goal of post-operative (adjuvant) treatment is therefore to prevent or delay recurrence. Adjuvant immunotherapy with pembrolizumab is already a standard option in stage IIB, IIC and III melanoma (KEYNOTE-054, KEYNOTE-716).
According to the companies, INTerpath-001 is the first positive phase 3 result for an individualized neoantigen therapy and for an mRNA-based cancer therapy. In the phase 2b KEYNOTE-942 trial, the 5-year recurrence-free survival HR was 0.51; the phase 3 trial showed a benefit in the same direction in a much larger population. This does not mean the therapy is ready for routine use: Merck and Moderna are engaging with regulators, but there is no approval yet and overall survival data are awaited.
How does intismeran (personalized mRNA therapy) work in melanoma?
Intismeran is an mRNA therapy built from the mutations in a patient's own tumor and encoding up to 34 neoantigens. It aims to help the immune system recognize tumor cells. Each product is designed individually from tumor and normal DNA sequencing. In INTerpath-001 it was given with pembrolizumab after surgery to reduce recurrence; no survival advantage is shown yet.
How was the INTerpath-001 trial conducted?
INTerpath-001 is a randomized, double-blind, placebo- and active-comparator-controlled phase 3 trial (NCT05933577). Both arms received standard adjuvant pembrolizumab; the difference was whether patients also received intismeran or placebo.
| Feature | Details |
|---|---|
| Patients | 1,137 patients; 2:1 randomization (757 intismeran + pembrolizumab, 380 placebo + pembrolizumab) |
| Disease | Completely resected AJCC 8th edition stage IIB/IIC, III or IV cutaneous melanoma; no prior systemic therapy; surgery no more than 13 weeks before randomization; ocular and mucosal melanoma excluded |
| Other requirements | ECOG performance status 0–1; tumor sample suitable for next-generation sequencing |
| Intismeran | 1 mg intramuscularly every 3 weeks, up to 9 doses |
| Pembrolizumab | 400 mg intravenously every 6 weeks, up to 9 cycles (about 1 year) |
| Primary endpoint | Recurrence-free survival: time from randomization to any recurrence (investigator-assessed) or death from any cause |
| Secondary endpoints | Distant metastasis-free survival, overall survival, safety, quality of life |
| Participants | Median age 61; about 60% male; randomization stratified by risk-based stage and age |
| Follow-up | Median 24.6 months (data cutoff 30 June 2026) |
Figure 1 · How and when was treatment given?
INTerpath-001 trial flow (simplified)
What were the recurrence-free and distant metastasis-free survival results?
All comparisons below are between the two arms of the same trial, so they are direct comparisons. Colored bars are intismeran + pembrolizumab; gray bars are placebo + pembrolizumab.
24-month rates
Recurrence-free and distant metastasis-free survival · ITT and mITT
Recurrence-free survival (RFS) · 24 months
Distant metastasis-free survival (DMFS) · 24 months
RFS · mITT sensitivity analysis · 24 months
HR: RFS 0.58, DMFS 0.62, mITT RFS 0.51. The mITT analysis excludes patients who did not receive at least one planned dose of intismeran/placebo.
| Endpoint | HR (95% CI) | Events (combination / control) | 24-month rate |
|---|---|---|---|
| Recurrence-free survival (primary, ITT) | 0.58 (0.45–0.75); p<0.001 | 136 (18.0%) / 111 (29.2%) | 82.2% / 70.0% |
| Distant metastasis-free survival (ITT) | 0.62 (0.45–0.85); p=0.002 | 89 (11.8%) / 71 (18.7%) | 88.5% / 80.2% |
| Recurrence-free survival (mITT) | 0.51 (0.39–0.67) | – | 84.2% / 70.4% |
| Distant metastasis-free survival (mITT) | 0.55 (0.40–0.77) | – | 90.1% / 80.7% |
| Overall survival | 0.77 (0.45–1.31); p=0.33 | – | Immature |
Median RFS and median DMFS have not been reached in either arm. Endpoints were tested hierarchically (RFS, then DMFS, then overall survival); overall survival did not cross the prespecified significance boundary and follow-up continues.
In which patient groups was a benefit seen?
The benefit pointed in the same direction in most prespecified subgroups. In small subgroups, confidence intervals crossed 1; no firm conclusions can be drawn for those groups.
| Subgroup | RFS HR (95% CI) | DMFS HR (95% CI) |
|---|---|---|
| Stage IIB/IIC/IIIA/IIIB | 0.60 (0.41–0.88) | 0.65 (0.41–1.02) |
| Stage IIIC/IIID/IV | 0.57 (0.41–0.79) | 0.59 (0.39–0.91) |
| Under 65 years | 0.65 (0.47–0.91) | – |
| 65 years and older | 0.53 (0.36–0.77) | – |
In the stage IIB–IIIB subgroup the DMFS confidence interval includes 1. In the US subgroup, the DMFS HR of 1.77 (95% CI 0.38–8.35) is based on only 10 events and is too uncertain to interpret.
Why was there no difference in the first 6 months?
In the trial, pembrolizumab starts at randomization, while intismeran is made for each patient and given once the product is ready. The median time to the first intismeran dose was 64 days. In the first 6 months the curves overlapped (RFS HR 0.99; 95% CI 0.66–1.49; DMFS HR 1.01; 95% CI 0.58–1.79).
After month 6, a prespecified sensitivity analysis gave an RFS HR of 0.42 (95% CI 0.30–0.58) and a DMFS HR of 0.50 (95% CI 0.34–0.73). The companies and investigators interpret this as the benefit emerging once the immune response has developed. However, this is a sensitivity analysis; the HR of 0.58 in the main analysis should be used as the effect size.
What are the most common side effects during treatment?
The safety profile was consistent with previously reported data for intismeran plus pembrolizumab; no new safety signal was reported. Investigators described the added side effects of the combination as low-grade and transient.
Most common adverse events and severe events
Intismeran + pembrolizumab vs placebo + pembrolizumab
Fever (any cause, any grade)
Injection-site pain
Fatigue
Influenza-like illness
Grade 3 or higher event of any cause
Treatment-related grade 3–5 event
Red bars mark severe events in the combination arm that need attention. The comparison is between the two arms of the same trial.
| Measure | Intismeran + pembrolizumab | Placebo + pembrolizumab |
|---|---|---|
| Any treatment-related event | 95.8% | 90.0% |
| Serious treatment-related event | 9.8% | 11.1% |
| Discontinuation of any study drug due to a treatment-related event | 14.0% | 8.7% |
| Discontinuation of both drugs due to an event | 6.5% | 5.3% |
| Immune-mediated events of interest for pembrolizumab | 36.0% | 34.7% |
| Treatment-related loss of life | 2 patients (0.3%); both attributed to pembrolizumab | – |
Intismeran did not increase the immune-mediated side effects associated with pembrolizumab. Treatment completion was similar in the two arms (69.8% vs 69.1%); discontinuation because of recurrence was less frequent in the combination arm (10.8% vs 17.9%). The known immune-mediated side effects of pembrolizumab (thyroid, bowel, liver, lung and others) still need monitoring in both arms.
How is a personalized therapy prepared in practice?
- A tumor sample is required: The patient's tumor and normal DNA are sequenced, and an mRNA encoding up to 34 neoantigens is designed. Of 1,749 patients screened, 302 (17.3%) could not enter the trial because the tumor sample was inadequate.
- Manufacturing largely succeeded: Product was manufactured for more than 99% of patients in the combination arm; the maximum number (34) of neoantigens was identified in 91% of randomized patients.
- There is a preparation time: The median time to the first intismeran dose was 64 days (about 9 weeks); patients received a median of 9 doses.
- Completion rates were similar: Treatment was completed by 69.8% in the combination arm and 69.1% in the pembrolizumab arm.
Which results are established, and which are not yet clear?
Figure 2 · Evidence map
INTerpath-001, ESMO 2026 LBA1
- Approval: Intismeran has not yet been approved by any health authority worldwide; Merck and Moderna state that they are engaging with regulators. It is therefore not available as a licensed therapy.
- Reimbursement: As an unapproved therapy, there is no reimbursement. Coverage for adjuvant pembrolizumab differs by country and insurer and should be checked locally.
- Access: The sources do not mention any access route outside the trial. INTerpath-001 is listed as active but no longer recruiting.
- What should patients do? Post-operative melanoma treatment is planned by a tumor board according to stage, risk and the patient's condition. Discuss the currently available options, including adjuvant pembrolizumab, with your own oncologist.
Frequently asked questions
- Is intismeran a cancer vaccine?
- Intismeran is an mRNA-based individualized neoantigen therapy made from a patient's own tumor and is often called a "personalized cancer vaccine". It does not prevent the disease; it aims to strengthen the immune response against tumor cells that may remain after surgery.
- Is this treatment available now?
- No. Intismeran is not approved in any country. The results have been accepted for publication in the New England Journal of Medicine and the companies are engaging with regulators; the decision and its timing are unknown.
- Did it improve overall survival?
- Not yet shown. Overall survival data are immature and did not reach the significance boundary (HR 0.77; 95% CI 0.45–1.31). Follow-up continues.
- What are the side effects?
- The most common were fever, injection-site pain, fatigue and flu-like symptoms, mostly low-grade and transient. Severe (grade 3–5) treatment-related events were similar in the two arms (14.2% vs 13.4%).
Glossary
- Adjuvant therapy
- Treatment given after surgical removal of the visible tumor to prevent recurrence.
- Recurrence-free survival (RFS)
- Time from randomization to recurrence of disease at any site or death from any cause.
- Distant metastasis-free survival (DMFS)
- Time until spread to distant organs or death.
- Neoantigen
- Protein fragment created by tumor-specific mutations that the immune system can recognize as foreign.
- Hazard ratio (HR)
- A value below 1 means a lower risk of an event (recurrence or death) in the experimental arm; 0.58 means about a 42% lower risk.
- ITT and mITT
- ITT analyzes everyone randomized; mITT is a sensitivity analysis of those who received at least one dose as planned.
DROZDOGAN Academy Commentary
INTerpath-001 is the first randomized phase 3 dataset showing that a personalized mRNA therapy adds recurrence control on top of adjuvant pembrolizumab; a survival benefit has not yet been confirmed.
⚡ Why it matters
Pembrolizumab has been a standard adjuvant option in melanoma for years, and this is the first phase 3 trial to show added benefit on top of it. It also suggests that an individualized approach can work in a large patient population.
✅ Strengths
Randomized, double-blind, placebo-controlled design; 1,137 patients; both the primary and the key secondary endpoint were significant; the mITT analysis and most subgroups pointed the same way; safety shows no marked added burden beyond pembrolizumab's known profile.
⚠️ Limitations
Median follow-up is 24.6 months and overall survival is not significant. The overlapping curves in the first 6 months and the HR of 0.42 afterward come from a sensitivity analysis; the main effect is HR 0.58. The comparator is pembrolizumab alone. The data are company-sponsored and the full text has not yet been reviewed.
🩺 In practice
Because the therapy is not approved, it is not an available option for patients today. Standard adjuvant options after melanoma surgery should continue to be discussed at the tumor board.
❓ Open questions
Will there be an overall survival benefit? In which stages and patients is the benefit greatest? How will inadequate tumor samples (17.3%) and the 64-day preparation time be handled in practice? What about long-term safety, cost and access?
Bottom line: A strong and encouraging phase 3 result for recurrence control; until the effect on survival and the regulatory path are clear, it should be interpreted with caution.
- This article was prepared in October 2026.
- Figures are taken from the Merck/Moderna company statement of 22 October 2026 and from OncLive, CancerNetwork and Targeted Oncology reports on the ESMO 2026 LBA1 presentation (24 October 2026; presenter G. V. Long). The results have been accepted for publication in the New England Journal of Medicine; the full text was not accessible.
- The overall survival HR (0.77), the number of treatment-related deaths, serious event and discontinuation rates and the manufacturing data come from a secondary source (CancerNetwork); the company statement only mentions a favorable trend for overall survival.
- The data come from a company-sponsored (Merck/Moderna) trial. The "first phase 3" wording belongs to the companies and is limited to individualized neoantigen/mRNA-based therapy; other cell-based cancer vaccines have been approved before.
- The abstract was released early on 22 October 2026 after an embargo breach; reports after the presentation are consistent with these data.
- The charts show only direct comparisons between arms of the same trial; the comparison with KEYNOTE-942 (phase 2b) is indirect and is mentioned only for context.
- The figures are derived from verified statements in the text and contain no new data. The Academy commentary is our own.
References
- Merck & Moderna. Merck and Moderna will present results from landmark Phase 3 INTerpath-001 trial of intismeran autogene plus KEYTRUDA at ESMO 2026 Presidential Symposium. News release, 22 Oct 2026. https://www.merck.com/news/merck-and-moderna-will-present-results-from-landmark-phase-3-interpath-001-trial-for-intismeran-autogene-plus-keytruda-pembrolizumab-at-esmo-2026-presidential-symposium/
- Long GV. INTerpath-001: Phase 3 study of intismeran autogene plus pembrolizumab vs pembrolizumab alone for adjuvant treatment of resected stage IIB-IV melanoma. ESMO Congress 2026, Madrid, Presidential Symposium I, LBA1.
- CancerNetwork. INTerpath-001 data detail survival, subgroup, and safety findings in melanoma. 24 Oct 2026. https://www.cancernetwork.com/view/interpath-001-data-detail-survival-subgroup-and-safety-findings-in-melanoma
- Targeted Oncology. Personalized mRNA vaccine intismeran plus pembro cuts melanoma recurrence. 23 Oct 2026. https://www.targetedonc.com/view/personalized-mrna-vaccine-intismeran-autogene-pembrolizumab-cuts-melanoma-recurrence
- OncLive. Intismeran autogene plus pembrolizumab meets RFS and DMFS end points in resected stage IIB-IV melanoma. 19 Aug 2026. https://www.onclive.com/view/intismeran-autogene-plus-pembrolizumab-meets-rfs-dmfs-end-points-in-resected-melanoma
- ClinicalTrials.gov. INTerpath-001 (NCT05933577). https://clinicaltrials.gov/study/NCT05933577
- Carlino MS, Khattak A, Meniawy T, et al. Intismeran autogene plus pembrolizumab in resected melanoma: 5-year update of KEYNOTE-942. J Clin Oncol. 2026;44(suppl 16):9500. https://doi.org/10.1200/JCO.2026.44.16_suppl.9500
- Luke JJ, Ascierto PA, Khattak MA, et al. Pembrolizumab vs placebo as adjuvant therapy in resected stage IIB or IIC melanoma: final analysis of DMFS in KEYNOTE-716. J Clin Oncol. 2024;42(14):1619-1624. https://doi.org/10.1200/JCO.23.02355
- Eggermont AMM, Blank CU, Mandala M, et al. Adjuvant pembrolizumab versus placebo in resected stage III melanoma (KEYNOTE-054). N Engl J Med. 2018;378:1789-1801. https://doi.org/10.1056/NEJMoa1802357
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