WT1 Trio Peptide-Based Cancer Vaccine for Rare Cancers Expressing Shared Target WT1.

Area of Science:

• Immunology
• Oncology
• Vaccinology

Background:

• Standard treatments for rare cancers are lacking.
• The Wilms' Tumor 1 (WT1) antigen is a shared target in various rare cancers.
• Clinical trials for rare cancers are challenging due to small patient populations.

Purpose of the Study:

• To evaluate the safety and efficacy of a biweekly WT1 tri-peptide-based vaccine (WT1 Trio) in patients with recurrent or advanced rare cancers.
• To compare the immunogenicity of WT1 Trio against a weekly WT1-235 CTL peptide vaccine.
• To assess clinical outcomes including antibody production, skin reactions, and disease progression.

Main Methods:

• A clinical trial involving 45 patients with WT1-expressing rare cancers and specific HLA types (HLA-A*24:02 or 02:01).
• Patients received the biweekly WT1 Trio vaccine.
• Primary endpoints included immunoglobulin G (IgG) antibody production and delayed-type hypersensitivity (DTH) reactions.
• Secondary endpoints focused on safety and clinical efficacy.

Main Results:

• WT1 Trio induced a significantly higher IgG antibody response (88.0%) compared to the weekly vaccine (62.5%).
• DTH positivity rates were comparable between WT1 Trio (62.9%) and the weekly vaccine (60.7%).
• The vaccine was generally safe, with one case of severe myasthenia gravis-like symptoms.
• Stable disease was achieved in 33.3% of patients after 3 months.

Conclusions:

• The biweekly WT1 Trio vaccine, incorporating a WT1 helper T lymphocyte peptide, elicits a more robust immune response targeting WT1 than the weekly CTL peptide vaccine.
• WT1-targeted immunotherapy represents a promising therapeutic avenue for rare cancers.
• The study highlights the potential of shared antigen-targeted vaccines in overcoming challenges in rare cancer clinical trials.