Testing a Combined WT1 Peptide Vaccine for Recurring Brain Cancer

This was a Phase I clinical trial enrolling 14 patients with recurrent malignant glioma (2 grade 3 and 12 grade 4) who were HLA-A*24:02-positive. Patients received weekly alternating injections: one week a vaccine with 3 mg of WT1 HLA class I peptide alone, and the next week a cocktail combining the class I peptide with one of three escalating doses of the WT1 HLA class II peptide (0.75, 1.5, or 3 mg). After 6 weeks without significant adverse effects, vaccination continued at 2-4-week intervals. The primary endpoint was safety, with immunological responses and survival as secondary measures.

Peptide-based cancer vaccines targeting tumor-associated proteins like WT1 represent a promising immunotherapy strategy. This trial demonstrated that combining class I and class II peptides — which activate different arms of the immune system — is safe, opening the door for larger efficacy trials. For patients with recurrent malignant glioma, who have very limited treatment options, this approach could eventually expand the therapeutic toolkit.

Cancer peptide vaccines have gained traction as a way to train the immune system to recognize and attack tumors. WT1 is one of the most studied tumor-associated antigens, and earlier trials using only HLA class I peptides showed promise. By adding an HLA class II peptide to engage helper T cells alongside killer T cells, this cocktail approach aims to produce a more robust and durable immune response. Demonstrating its safety is an essential first step toward Phase II and III trials.

This was a small Phase I trial focused primarily on safety, not efficacy, so the survival data should be interpreted cautiously. With only 14 patients and no control group, it is impossible to determine whether the vaccine improved outcomes compared to natural disease course. The study was also restricted to HLA-A*24:02-positive patients, limiting the applicability to a subset of the population. Three patients dropped out early due to disease progression, which may have biased the completion and response data.