SNMMI: Does Vaccination Enhance Pluvicto Efficacy in mCRPC?

Emerging research findings suggest thatprior vaccination for prostate cancer-specific antigens may bolster the effectiveness of treatment with ¹⁷⁷Lu-PSMA-617 in patients with metastatic castration-resistant prostate cancer (mCRPC).

For the retrospective study, recently presented at the Society of Nuclear Medicine and Molecular Imaging (SNMMI) conference, researchers evaluated the impact of prior vaccination targeting prostatic acid phosphatase (PAP) or in combination with the androgen receptor antigen. The cohort of 126 patients with mCRPC included 19 patients treated with ¹⁷⁷Lu-PSMA-617 (Pluvicto, Novartis) who had prior vaccination and 17 standard-of-care patients who had androgen deprivation therapy (ADT) and taxane-based chemotherapy, according to the study.

Noting a median follow-up time of 11.6 months, researchers found that 73.7 percent of patients with the combination of prior vaccination and ¹⁷⁷Lu-PSMA-617 had a PSA50 response. In comparison, 55.6 percent of unvaccinated patients who had ¹⁷⁷Lu-PSMA-617 achieved a PSA50 response and 23.5 percent of standard-of-care patients had a PSA50 response, according to the researchers.

For patients treated with ¹⁷⁷Lu-PSMA-617, the study authors found that prior vaccination doubled the rate of two-year overall survival in comparison to unvaccinated patients (47.6 percent vs. 23.5 percent).

(Editor’s note: For additional coverage from the SNMMI conference, click here.)

“Prior vaccination against prostate cancer antigens may enhance the clinical efficacy of ¹⁷⁷Lu-PSMA-617 therapy in mCRPC, without impairing prostate antigen-specific T cell response,” noted lead study author Bryce Wei Quan Tan, MD, who is affiliated with Singapore General Hospital in Singapore, and colleagues.

After multivariable analysis, the researchers noted that prior vaccination was associated with over a sevenfold higher likelihood of a higher PSA50 response with ¹⁷⁷Lu-PSMA-617 and a 70 percent reduction in mortality risk.

“Prospective studies on the combination therapy of vaccinations and ¹⁷⁷Lu-PSMA are warranted,” added Tan and colleagues.

(Editor’s note: For related content, see “SNMMI: What Early Research Reveals About the Alpha-Emitting Radioconjugate ATNM-400 for Prostate Cancer,” “Early SPECT/CT Response After Pluvicto May Help Predict Survival in Patients with mCRPC” and “Could Pluvicto Be a First-Line Systemic Treatment for Patients with Oligometastatic Hormone-Sensitive PCa?”)

Reference

1. Tan BWQ, Shim D, Lee C, et al. Immunological priming improves efficacy of ¹⁷⁷Lu-PSMA-617 in mCRPC: a retrospective cohort study. Presented at the Society of Nuclear Medicine and Molecular Imaging (SNMMI) conference, May 30-June 2, Los Angeles. Available at: https://jnm.snmjournals.org/content/67/supplement_1/261187 .