Researchers at The University of Texas MD Anderson Cancer Center have just concluded a phase II trial on a tumor-specific vaccine that combined with an immune checkpoint inhibitor managed to shrink cancerous formations in 30% of patients.
“That encouraging response rate is about twice the rate produced by PD1 checkpoint inhibitors in previous clinical trials, so these results will lead to larger, randomized clinical trials of this combination”, said Bonnie Glisson, M.D., professor of Thoracic/Head and Neck Medical Oncology at MD Anderson.
The findings were published in the latest issue of JAMA Oncology. The article details how the combination of the ISA101 vaccine that targets peptides produced by the HPV16 genotype of the virus, along with nivolumab, a checkpoint inhibitor responsible for blocking the activation of PD-1 on T cells, works together.
On a clinical trial conducted on 24 participants, eight (33%) had tumor response with a median duration of 10.3 months. The overall median survival rate was 17.5 months and progression-free survival was 2.7 months. 70% of patients survived past the initial 12 months.
In the press release, Mrs. Glisson remarked that “vaccines are revving up the immune system, but the immunosuppressive tumor microenvironment probably prevents them from working. Our thinking was that inhibition of PD-1 would address one mechanism of immunosuppression, empowering the vaccine-activated T lymphocytes to attack the cancer“.
HPV is at the origin of most cervical and oropharyngeal cancers, and HPV16 and HPV18 are the most common genotypes that favor cancer development. This new combined immunotherapy course was designed to specifically target these viruses.
Furthermore, the team reported no serious side effects. They hope to build further on these promising results, as every step so far has yielded incremental improvements.