Lower doses of immunotherapy for skin cancer give better results, study suggests

According to a new study, lower doses of approved immunotherapy for malignant melanoma can give better results against tumors, while reducing side effects. This is reported by researchers at Karolinska Institutet in the Journal of the National Cancer Institute.

“The results are highly interesting in oncology, as we show that a lower dose of an immunotherapy drug, in addition to causing significantly fewer side effects, actually gives better results against tumors and longer survival,” says last author Hildur Helgadottir, a researcher at the Department of Oncology–Pathology at Karolinska Institutet, who led the study.

Lower dose regimen in Sweden

The traditional dose of nivolumab and ipilimumab is the one that is approved and established. Due to the extensive side effects, Sweden has increasingly begun to use a treatment regimen with a lower dose of ipilimumab, which is the most expensive part of this immunotherapy and causes the most side effects.

“In Sweden, we have greater freedom to choose doses for patients, while in many other countries, due to reimbursement policies, they are restricted by the doses approved by the drug authorities,” says Hildur Helgadottir.

Study results and patient outcomes

The study included nearly 400 patients with advanced, inoperable malignant melanoma, the most serious form of skin cancer. The study shows that the regimen with the lower dose of ipilimumab is more effective, with a higher proportion of patients responding to treatment, 49%, compared to the traditional dose, 37%.

Progression-free survival, the time the patient lives without the disease worsening, was a median of nine months for the lower dose, compared to three months for the traditional dose. Overall survival was also longer, 42 months compared to 14 months.

Serious side effects were seen in 31% of patients in the low-dose group, compared to 51% in the traditional group.

Potential impact and study limitations

“The new immunotherapies are very valuable and effective, but at the same time they can cause serious side effects that are sometimes life-threatening or chronic. Our results suggest that this lower dosage may enable more patients to continue the treatment for a longer time, which is likely to contribute to the improved results and longer survival,” says Hildur Helgadottir.

There were some differences between the two treatment groups, but even after adjusting for several factors such as age and tumor stage, the better outcome for the lower dose of ipilimumab remained. The study is a retrospective observational study and therefore it is not possible to definitively establish a causal relationship.