Dr. Ravi A Madan, M.D.

M9241 + SBRT

for Prostate Cancer

Background: Prostate cancer is often treated with radiation and ADT (ADT is androgen deprivation therapy). Up to 30% of these cancers recur within 5 years of treatment. Researchers want to see if a new drug (M9241) can help the immune system to fight prostate cancer. Objective: To find what doses of M9241 are safe in people who are treated for prostate cancer. Also, to see what effects M9241 has on the immune system. Eligibility: People aged 18 and older with high- and intermediate-risk prostate cancer. Their cancer must not have spread to other parts of the body. Design: The study will last 7 months. Participants will be screened. They will share their medical history. They will also have: \<TAB\>A physical exam \<TAB\>Routine blood and urine tests \<TAB\>Imaging scans of the chest, abdomen, and pelvis \<TAB\>A bone scan \<TAB\>A tumor biopsy \<TAB\>A specialized MRI. Participants will lie face down on the MRI scanner table. An antenna that receives a signal may be placed in the rectum. All participants will be treated with radiation therapy and ADT. Some participants will also receive M9241 as an injection under the skin. This treatment will start 4 weeks after the radiation has ended. Participants will receive a total of 3 doses. The injections will be 4 weeks apart. Some screening tests will be repeated at each visit. Participants who do not receive M9241 will also have screening tests during the treatment period. Participants will return for follow-up about 1 month after the last treatment or set of tests.