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Original article: TRIMELVax: la vacuna chilena hecha con «proteína de loco» que enciende una esperanza contra el cáncer de piel avanzado

At a laboratory in El Salvador Hospital, Santiago, a team of researchers achieved what once seemed impossible: transforming a common Chilean mollusk into an unexpected ally in the fight against aggressive skin cancer.

The Citizen

The Silent Enemy Growing in Chile

Malignant melanoma is the most dangerous type of skin cancer, originating in melanocytes (the cells responsible for skin pigment). Once it spreads to other parts of the body, it becomes extremely difficult to treat. In Chile, the situation is alarming: deaths from this disease have increased by around 60% over the last decade. In 2024 alone, there were over 620 fatalities, the highest figure recorded in two decades, with 53% of victims being men, particularly among those aged 60 to 79 years.

In response to this grim scenario, treatments have evolved. In recent years, immunotherapies using checkpoint inhibitors (like anti-PD-1) have revolutionized melanoma management, extending the average survival of metastatic patients from about 10-11 months to 36 months, thanks to therapies developed by the same scientific team. Nevertheless, a significant percentage of patients do not respond or develop resistance. This is where TRIMELVax comes into play: a vaccine created for those who have run out of options.

What is TRIMELVax and Why Does It Contain «Loco» Protein?

TRIMELVax is the result of years of research conducted at the University of Chile and the biotechnology company Oncobiomed. It is not a preventive vaccine like those for COVID-19; instead, it is a therapeutic vaccine: administered to individuals already diagnosed with the disease, it aims to train their immune system to combat tumors more effectively.

How is it made? Scientists extract human melanoma cells and subject them to a «thermal shock» (controlled heating) before grinding them to obtain tumor lysate. This extract is then combined with a secret ingredient: a natural adjuvant derived from the hemocyanin of the Concholepas concholepas, popularly known as «loco».

«The goal is to enhance immunogenicity and activate the immune system more vigorously,» explains immunologist Flavio Salazar, former Minister of Science and one of the project leaders.

The «loco» acts as an enhancer: it causes localized inflammation at the injection site, drawing in defensive cells and keeping them on high alert. Thanks to this, T lymphocytes (the soldiers of the immune system) learn to recognize and destroy cancerous cells, even in «cold tumors» that are nearly invisible to the body’s natural defenses.

Clinical Trial Results: Numbers That Inspire Hope

The first human trial, results of which were published in the prestigious British Journal of Cancer (part of the Nature group), included 17 patients with stage IV melanoma who had already failed standard anti-PD-1 immunotherapy. All received four subcutaneous doses of TRIMELVax, one every four weeks.

Safety: No serious adverse effects were recorded. Most patients experienced mild to moderate reactions (grade 1 or 2), and only two suffered manageable grade 3 events. There were no grade 4 or 5 toxicities.

Clinical Activity: While no patient achieved complete remission, one patient had a partial response, six stabilized their disease, and three maintained stable disease for over six months. Together, the disease control rate was 41%. The median overall survival was 14 months, with progression-free survival reaching 5.2 months.

Immunological Evidence: The vaccine did indeed activate the immune system. Among the nine patients analyzed, six exhibited delayed hypersensitivity responses (a sign of immune memory). Furthermore, blood analysis showed an increase in CD8⁺ T cells with CXCR3 markers and a decrease in CD39, a pattern consistent with improved tumor-fighting capabilities.

The most remarkable case involved a patient with pulmonary metastasis: their body demonstrated a massive expansion of T cells with stem cell-like properties (TCF1⁺PD-1⁺) and an enrichment of CD8⁺ T cells loaded with perforin and granzyme B (the agents used by the immune system to destroy tumor cells).

The most significant aspect of this work is having conducted a clinical study with a cancer vaccine designed and developed in Chile. All components were discovered, designed, and produced in the country, highlights Salazar.

Limitations and Next Steps

The study has significant limitations: it is a Phase I trial primarily designed to evaluate safety rather than efficacy. It did not include a control group, and the patient number is small. The researchers themselves acknowledge this: «Although this type of study does not demonstrate definitive efficacy, we observed signals that we consider promising,» states Dr. Roberto Estay, an oncologist at El Salvador Hospital who led the trial.

The next step, currently underway, will be to progress towards larger, controlled clinical trials (Phase II and III) to confirm whether the vaccine genuinely prolongs patient survival beyond what was observed in this initial stage.

A Chilean Immunotherapy Ecosystem

TRIMELVax is not an isolated project. It represents the forefront of a line of developments that has already treated over 400 patients in Chile with other vaccines like TAPCells and LycellVax. Led by Dr. Flavio Salazar and Dr. Mercedes López, the team has positioned Chile as a relevant player in the development of third-generation immunotherapies, with international patents protecting their technologies in over 150 countries.

The hemocyanin from the «loco» is the result of years of work by Dr. María Inés Becker of Biosonda, who extracted and developed this immuno-stimulatory component from its inception, competing with the hemocyanin from Alaska’s chitons, which had historically dominated the market.

A Light at the End of the Tunnel

For the first time, an oncological vaccine designed entirely in Chile, with 100% domestic components and tested in a public hospital, shows clear signs of potentially helping patients who have stopped responding to conventional therapies.

It is not a miraculous cure. However, for those who have heard, «we have no more options,» an injection every four weeks that activates their own defenses against cancer—with the help of a Chilean mollusk—is much more than an experiment. It is a testament to how homegrown science can, with patience and rigor, transform the ocean into medicine and local biology into global hope.

The Citizen

La entrada TRIMELVax: The Chilean Vaccine Made with «Loco» Protein Sparks Hope Against Advanced Skin Cancer se publicó primero en El Ciudadano.