{"id":5610,"date":"2026-08-19T09:49:50","date_gmt":"2026-08-19T13:49:50","guid":{"rendered":"https:\/\/humanbodycalculator.com\/blogs\/?p=5610"},"modified":"2026-08-21T13:32:15","modified_gmt":"2026-08-21T17:32:15","slug":"moderna-melanoma-vaccine","status":"publish","type":"post","link":"https:\/\/humanbodycalculator.com\/blogs\/moderna-melanoma-vaccine\/","title":{"rendered":"mRNA Vaccine: How It Works, Benefits &amp; Risks"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\"><strong>The Moderna melanoma vaccine \u2014 known clinically as mRNA-4157, V940, or intismeran autogene \u2014 is an investigational, personalized mRNA shot given after melanoma surgery, alongside the immunotherapy drug Keytruda (pembrolizumab), to lower the chance the cancer comes back.<\/strong> It is built from each patient&#8217;s own tumor DNA rather than off a factory shelf, and on <strong>August 19, 2026<\/strong>, Merck and Moderna announced that the vaccine just cleared its first-ever Phase 3 trial. Here&#8217;s what that means, how the shot actually works inside the body, and what the real benefits and risks look like based on the clinical data published so far.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Key Takeaways<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Not a preventive vaccine.<\/strong> This melanoma vaccine treats patients who already had melanoma surgically removed \u2014 it does not prevent skin cancer in healthy people.<\/li>\n\n\n\n<li><strong>Cuts recurrence risk nearly in half.<\/strong> In 5-year trial data, the combination reduced the risk of recurrence or death by 49% compared with Keytruda alone.<\/li>\n\n\n\n<li><strong>Just passed its biggest test.<\/strong> The Phase 3 INTerpath-001 trial met its main goals on August 19, 2026 \u2014 the first positive late-stage result ever recorded for an mRNA cancer therapy.<\/li>\n\n\n\n<li><strong>Not yet FDA-approved.<\/strong> It remains investigational; Merck and Moderna plan to file with regulators using the new Phase 3 data.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">What Is the mRNA Vaccine?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The Moderna melanoma vaccine goes by several names depending on where you encounter it, which trips up a lot of readers:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>mRNA-4157<\/strong> \u2014 the original lab\/research code name<\/li>\n\n\n\n<li><strong>V940<\/strong> \u2014 Merck&#8217;s internal development code<\/li>\n\n\n\n<li><strong>Intismeran autogene<\/strong> \u2014 the official generic (INN) drug name assigned in 2025<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">All three refer to the same product. It is classified as an <strong>individualized neoantigen therapy (INT)<\/strong> \u2014 a type of personalized cancer vaccine \u2014 jointly developed by <a href=\"https:\/\/www.modernatx.com\/en-US\" target=\"_blank\" rel=\"noopener\">Moderna<\/a> and <a href=\"https:\/\/www.merck.com\/research\/oncology\/\" target=\"_blank\" rel=\"noopener\">Merck<\/a>. Unlike a flu shot or the Moderna COVID-19 vaccine, which are mass-produced and given to prevent infection, this is a <strong>therapeutic melanoma treatment<\/strong> manufactured individually for each patient from their own tumor tissue, then given after surgery in combination with Keytruda (pembrolizumab), Merck&#8217;s anti-PD-1 immunotherapy.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Breaking: The Phase 3 Trial Just Reported Success (August 2026)<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">On the morning of August 19, 2026, Merck and Moderna announced that the Phase 3 <strong>INTerpath-001<\/strong> trial (<a href=\"https:\/\/clinicaltrials.gov\/study\/NCT05933577\" target=\"_blank\" rel=\"noopener\">NCT05933577<\/a>) met its primary endpoint of recurrence-free survival (RFS) and a key secondary endpoint of distant metastasis-free survival (DMFS), according to the <a href=\"https:\/\/www.merck.com\/news\/merck-and-moderna-announce-phase-3-interpath-001-trial-of-intismeran-autogene-plus-keytruda-met-endpoints-of-recurrence-free-survival-rfs-and-distant-metastasis-free-survival-dmfs-in-patient\/\" target=\"_blank\" rel=\"noopener\">joint press release from Merck<\/a>. This is a genuinely big deal in oncology: it&#8217;s the first time any mRNA-based cancer therapy, and the first time any individualized neoantigen therapy, has posted a positive result in a late-stage, randomized trial.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The trial enrolled 1,137 patients with completely resected, high-risk (stage IIB\u2013IV) melanoma, randomized 2:1 to receive the vaccine plus Keytruda versus Keytruda alone. The companies have not yet released the exact percentage risk reduction from Phase 3 \u2014 those numbers will be presented at an upcoming international medical meeting and submitted to regulators. Merck also reported that <strong>no new safety signals<\/strong> turned up in the Phase 3 population, meaning the side-effect profile looked consistent with earlier trials.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\">&#8220;Today&#8217;s results represent a landmark moment for adjuvant melanoma treatment&#8230; [Intismeran] has the potential to establish a new treatment paradigm in the adjuvant melanoma setting, helping patients remain cancer-free for longer.&#8221;<\/p>\n<cite>\u2014 Professor Georgina Long, principal investigator of INTerpath-001 and Medical Director, Melanoma Institute Australia (<a href=\"https:\/\/www.merck.com\/news\/merck-and-moderna-announce-phase-3-interpath-001-trial-of-intismeran-autogene-plus-keytruda-met-endpoints-of-recurrence-free-survival-rfs-and-distant-metastasis-free-survival-dmfs-in-patient\/\" target=\"_blank\" rel=\"noopener\">source<\/a>)<\/cite><\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\">How Does the Moderna Melanoma Vaccine Work?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The mechanism is what sets this melanoma vaccine apart from any conventional cancer drug. It doesn&#8217;t attack the tumor directly \u2014 it trains the patient&#8217;s own immune system to recognize and destroy melanoma cells that might still be hiding in the body after surgery. Here&#8217;s the process, step by step:<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Tumor sequencing.<\/strong> After the patient&#8217;s melanoma tumor is surgically removed, a sample is sent for next-generation DNA sequencing to map its unique mutations.<\/li>\n\n\n\n<li><strong>Neoantigen selection.<\/strong> A proprietary algorithm scans those mutations and picks up to <strong>34 neoantigens<\/strong> \u2014 abnormal proteins found only on that patient&#8217;s cancer cells, not on healthy tissue.<\/li>\n\n\n\n<li><strong>Custom mRNA manufacturing.<\/strong> A synthetic mRNA strand encoding all 34 neoantigens is manufactured specifically for that one patient \u2014 essentially a one-of-a-kind prescription.<\/li>\n\n\n\n<li><strong>Lipid nanoparticle delivery.<\/strong> The mRNA is wrapped in a lipid nanoparticle (the same delivery technology used in Moderna&#8217;s COVID-19 vaccine) and injected.<\/li>\n\n\n\n<li><strong>Immune activation.<\/strong> The body&#8217;s cells read the mRNA and produce the neoantigen proteins, which are displayed to the immune system. This trains cancer-fighting T-cells to recognize those exact markers.<\/li>\n\n\n\n<li><strong>Combination with Keytruda.<\/strong> Pembrolizumab is given alongside the vaccine to block the PD-1 pathway that tumors use to hide from the immune system \u2014 effectively releasing the brakes on the T-cells the vaccine just trained.<\/li>\n<\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">In the trials, patients received the vaccine roughly once every three weeks for up to nine doses, alongside Keytruda infusions every six weeks, for about a year in total.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Benefits of the Moderna Melanoma Vaccine<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The clinical case for this <strong>personalized cancer vaccine<\/strong> rests on the Phase 2b <strong>KEYNOTE-942<\/strong> trial (<a href=\"https:\/\/clinicaltrials.gov\/study\/NCT03897881\" target=\"_blank\" rel=\"noopener\">NCT03897881<\/a>), which has now followed 157 patients for five years \u2014 an unusually long, mature dataset for a cancer therapy still in development. The benefit has held up at every checkpoint:<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Follow-Up Point<\/th><th>Reduced Risk of Recurrence\/Death (RFS)<\/th><th>Reduced Risk of Distant Metastasis (DMFS)<\/th><\/tr><\/thead><tbody><tr><td>~2 years (2023)<\/td><td>44%<\/td><td>65%<\/td><\/tr><tr><td>3 years (2024)<\/td><td>49%<\/td><td>62%<\/td><\/tr><tr><td>5 years (Jan 2026)<\/td><td>49%<\/td><td>59%<\/td><\/tr><tr><td>Phase 3 INTerpath-001 (Aug 2026)<\/td><td>Primary endpoint met*<\/td><td>Secondary endpoint met*<\/td><\/tr><\/tbody><\/table><figcaption class=\"wp-element-caption\">*Exact percentages from the Phase 3 trial have not yet been disclosed publicly; full data are expected at an upcoming medical conference. Data source: <a href=\"https:\/\/www.merck.com\/news\/moderna-merck-announce-5-year-data-for-intismeran-autogene-in-combination-with-keytruda-pembrolizumab-demonstrated-sustained-improvement-in-the-primary-endpoint-of-recurrence-free-survival-i\/\" target=\"_blank\" rel=\"noopener\">Merck\/Moderna 5-year data release<\/a>.<\/figcaption><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\">Why This Matters for Melanoma Patients<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Melanoma is aggressive once it spreads. The <a href=\"https:\/\/www.merck.com\/news\/merck-and-moderna-announce-phase-3-interpath-001-trial-of-intismeran-autogene-plus-keytruda-met-endpoints-of-recurrence-free-survival-rfs-and-distant-metastasis-free-survival-dmfs-in-patient\/\" target=\"_blank\" rel=\"noopener\">American Cancer Society estimates cited by Merck<\/a> put U.S. cases at roughly 112,000 new diagnoses and more than 8,500 deaths in 2026 alone, and most recurrences happen within the first two years after surgery, and most of those recurrences are metastatic rather than local. That&#8217;s the exact window this vaccine targets: the period right after surgery when microscopic cancer cells may still be circulating in the body, undetectable on scans but capable of regrowing the tumor later.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Moderna Melanoma Vaccine Side Effects &amp; Risks<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">No cancer therapy is risk-free, and this combination is no exception. Because the vaccine is always given with Keytruda, patients take on side effects from both drugs. Reporting from the trial&#8217;s 3-year data update, compiled by <a href=\"https:\/\/www.targetedonc.com\/view\/mrna-4157-plus-pembrolizumab-continues-to-improve-rfs-in-high-risk-melanoma\" target=\"_blank\" rel=\"noopener\">Targeted Oncology<\/a>, breaks down the most common reactions attributed specifically to the vaccine component:<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table><thead><tr><th>Side Effect<\/th><th>Reported Frequency<\/th><\/tr><\/thead><tbody><tr><td>Fatigue<\/td><td>~61%<\/td><\/tr><tr><td>Injection site pain<\/td><td>~56\u201357%<\/td><\/tr><tr><td>Chills<\/td><td>~49\u201350%<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">These are mostly mild-to-moderate and short-lived \u2014 similar to how you&#8217;d feel after an mRNA COVID-19 booster, just more frequent because of the repeated dosing schedule. More importantly, adding the vaccine did <strong>not<\/strong> meaningfully raise the rate of serious side effects: grade 3-or-higher treatment-related adverse events occurred in about 25% of patients on the combination versus 20% on Keytruda alone, and the vaccine did not increase immune-related adverse events on top of what Keytruda already causes.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">The Risks That Come From the Keytruda Half of Treatment<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Because pembrolizumab works by taking the brakes off the immune system, it carries its own, separately documented risk of <strong>immune-mediated adverse reactions<\/strong> \u2014 situations where the newly activated immune system attacks healthy organs by mistake. These can affect the lungs (pneumonitis), colon (colitis), liver, hormone-producing glands (thyroid, adrenal, pituitary), kidneys, or skin, and range from mild to serious. Full details are documented in Merck&#8217;s <a href=\"https:\/\/www.merck.com\/product\/usa\/pi_circulars\/k\/keytruda\/keytruda_pi.pdf\" target=\"_blank\" rel=\"noopener\">official KEYTRUDA prescribing information<\/a>, which any patient starting this regimen should review with their oncologist.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Patients on this melanoma treatment are monitored closely with regular bloodwork and check-ins specifically to catch these reactions early, since prompt treatment (usually corticosteroids) typically resolves them.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Is the Moderna Melanoma Vaccine FDA-Approved?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Not yet.<\/strong> As of August 2026, intismeran autogene (mRNA-4157\/V940) remains an investigational therapy \u2014 it is not commercially available, and no patient outside a clinical trial can currently receive it. Here&#8217;s the regulatory timeline so far:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>February 2023<\/strong> \u2014 FDA grants <a href=\"https:\/\/www.onclive.com\/view\/fda-grants-breakthrough-therapy-designation-to-mrna-4157-v940-plus-pembrolizumab-in-high-risk-melanoma\" target=\"_blank\" rel=\"noopener\">Breakthrough Therapy Designation<\/a>, a status meant to speed development of drugs that show substantial improvement over existing options.<\/li>\n\n\n\n<li><strong>July 2023<\/strong> \u2014 Phase 3 INTerpath-001 trial begins enrollment.<\/li>\n\n\n\n<li><strong>2025<\/strong> \u2014 Trial completes enrollment at 1,137 patients; the product receives its official generic name, intismeran autogene.<\/li>\n\n\n\n<li><strong>August 19, 2026<\/strong> \u2014 Phase 3 trial reports positive topline results; Merck and Moderna say they will now engage regulators on a formal filing.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Given the Breakthrough Therapy status and the positive Phase 3 readout, industry analysts widely expect an FDA filing within the next several months \u2014 but until that filing is reviewed and approved, this remains a treatment you can only access by enrolling in one of the ongoing INTerpath clinical trials.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Who Might Be Eligible?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">In the trials conducted so far, the melanoma vaccine has been studied in adults with <strong>completely resected, high-risk cutaneous melanoma<\/strong> \u2014 specifically stage IIB, IIC, III, or IV disease after surgical removal, in patients who have not yet received systemic therapy. It is an <em>adjuvant<\/em> treatment, meaning it&#8217;s given after surgery to lower recurrence risk, not as a treatment for active, unresectable, or already-metastatic disease. Beyond melanoma, Merck and Moderna are separately testing the same technology in non-small cell lung cancer, bladder cancer, and renal cell carcinoma, as part of a nine-trial development program called INTerpath.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Moderna Melanoma Vaccine vs. a Traditional Vaccine<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The word &#8220;vaccine&#8221; causes real confusion here, so it&#8217;s worth spelling out the difference plainly:<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table><thead><tr><th><\/th><th>Traditional Vaccine (e.g., flu, COVID-19)<\/th><th>Moderna Melanoma Vaccine (mRNA-4157)<\/th><\/tr><\/thead><tbody><tr><td>Purpose<\/td><td>Prevent infection in healthy people<\/td><td>Treat cancer, reduce recurrence after surgery<\/td><\/tr><tr><td>Who receives it<\/td><td>General public<\/td><td>Only diagnosed melanoma patients post-surgery<\/td><\/tr><tr><td>Manufacturing<\/td><td>Identical for everyone<\/td><td>Custom-built from each patient&#8217;s own tumor<\/td><\/tr><tr><td>Given with another drug?<\/td><td>No<\/td><td>Yes \u2014 always paired with Keytruda<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">Frequently Asked Questions<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Is the Moderna melanoma vaccine the same as the COVID-19 vaccine?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">No. Both use mRNA and lipid nanoparticle delivery technology, but they carry completely different genetic instructions and serve different purposes \u2014 one prevents a viral infection, the other trains the immune system to attack a patient&#8217;s own cancer cells.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">How is the Moderna melanoma vaccine given?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">It&#8217;s an injection, given roughly every three weeks for up to nine doses, alongside Keytruda infusions given every six weeks, over about a year following melanoma surgery.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">What are the most common melanoma vaccine side effects?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Fatigue, pain at the injection site, and chills are the most frequently reported reactions tied to the vaccine itself, each occurring in roughly half to two-thirds of patients. These are typically mild and temporary.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Can this vaccine prevent melanoma from ever developing?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">No. It is not a preventive shot for healthy people. It is only studied in patients who already had melanoma diagnosed and surgically removed, to help prevent that specific cancer from returning.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">When might the Moderna melanoma vaccine be available to patients?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">There&#8217;s no confirmed approval date. Following the positive August 2026 Phase 3 results, Merck and Moderna plan to present full data and begin discussions with regulators, which typically precedes a formal approval filing. Until an approval is granted, access remains limited to clinical trial participants.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Does insurance cover the Moderna melanoma vaccine?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Not applicable yet \u2014 since it isn&#8217;t FDA-approved or commercially available, there is no standard insurance coverage or pricing at this time. Coverage and cost will become relevant only after regulatory approval.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\"><strong>Also Read:<\/strong> <a href=\"https:\/\/humanbodycalculator.com\/blogs\/focal-therapy-for-prostate-cancer-benefits-risks-candidacy\/\">Focal Therapy for Prostate Cancer: Benefits, Risks &amp; Candidacy<\/a><\/p>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Medical Disclaimer:<\/strong> This article is for informational purposes only and does not constitute medical advice, diagnosis, or treatment. Intismeran autogene (mRNA-4157\/V940) is an investigational therapy and is not currently approved by the FDA or any regulatory agency; it is not available outside clinical trials. Always talk to a licensed oncologist or dermatologist about melanoma diagnosis, staging, and treatment options, including whether a clinical trial may be appropriate for you.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>The Moderna melanoma vaccine \u2014 known clinically as mRNA-4157, V940, or intismeran autogene \u2014 is an investigational, personalized mRNA shot &#8230; <\/p>\n<p class=\"read-more-container\"><a title=\"mRNA Vaccine: How It Works, Benefits &amp; Risks\" class=\"read-more button\" href=\"https:\/\/humanbodycalculator.com\/blogs\/moderna-melanoma-vaccine\/#more-5610\" aria-label=\"Read more about mRNA Vaccine: How It Works, Benefits &amp; Risks\">Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":5611,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[292],"tags":[],"class_list":["post-5610","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-cancer-oncology","resize-featured-image"],"_links":{"self":[{"href":"https:\/\/humanbodycalculator.com\/blogs\/wp-json\/wp\/v2\/posts\/5610","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/humanbodycalculator.com\/blogs\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/humanbodycalculator.com\/blogs\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/humanbodycalculator.com\/blogs\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/humanbodycalculator.com\/blogs\/wp-json\/wp\/v2\/comments?post=5610"}],"version-history":[{"count":3,"href":"https:\/\/humanbodycalculator.com\/blogs\/wp-json\/wp\/v2\/posts\/5610\/revisions"}],"predecessor-version":[{"id":5621,"href":"https:\/\/humanbodycalculator.com\/blogs\/wp-json\/wp\/v2\/posts\/5610\/revisions\/5621"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/humanbodycalculator.com\/blogs\/wp-json\/wp\/v2\/media\/5611"}],"wp:attachment":[{"href":"https:\/\/humanbodycalculator.com\/blogs\/wp-json\/wp\/v2\/media?parent=5610"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/humanbodycalculator.com\/blogs\/wp-json\/wp\/v2\/categories?post=5610"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/humanbodycalculator.com\/blogs\/wp-json\/wp\/v2\/tags?post=5610"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}