Immunotherapy Enhances Radiation Benefits in Localized Prostate Cancer

A recent study indicates that combining the investigational immunotherapy aglatimagene with radiation therapy significantly enhances disease-free survival in patients with intermediate- or high-risk localized prostate cancer. Conducted by the Johns Hopkins University School of Medicine and associated centers, this multicenter clinical trial involved 745 men across the U.S. and Puerto Rico and was published in The Lancet Oncology.

The trial participants received either direct injections of aglatimagene into the prostate along with the oral prodrug valacyclovir and radiation therapy, or a placebo with valacyclovir and radiation therapy. A median follow-up period of 50.3 months revealed that patients in the aglatimagene group experienced longer disease-free survival compared to the placebo group. Specifically, 23% of the aglatimagene-treated group faced cancer progression, recurrence, or death, compared to 31% in the placebo group. Moreover, the median disease-free survival in the aglatimagene cohort was not reached, compared to 86.1 months in the placebo group.

The study found that 17% of patients receiving aglatimagene had recurrence or prostate cancer-related death, a notable improvement over 25% in the placebo group. Additionally, 67% of those treated with aglatimagene achieved very low prostate-specific antigen (PSA) levels, compared to 59% in the placebo group, indicating better cancer control.

The immunotherapy leverages a modified virus to deliver a cancer-fighting gene into tumor cells, disrupting DNA replication and stimulating an immune response. This pivotal phase 3 trial demonstrates a reduction in disease recurrence, as 80% of aglatimagene-treated patients presented with negative biopsy results approximately two years post-radiation therapy, compared to 63% in the placebo group.

Side effects of the treatment were predominantly mild to moderate, with severe side effects reported in 8% of the aglatimagene group and 7% of the placebo group. No treatment-related deaths were noted.

As detailed by researchers, while these findings could mark significant progress for men with localized prostate cancer, further investigations are required to assess long-term outcomes and potential reductions in the need for subsequent therapies. The study was conducted under a Special Protocol Assessment agreed upon with the FDA, and ongoing long-term follow-ups aim to solidify these findings.