T-Cell Clonality After Stereotactic Body Radiation Therapy Alone and in Combination With the Immunocytokine M9241 in Localized High- and Intermediate-Risk Prostate Cancer Treated With Androgen Deprivation Therapy

In the safety lead in, M9241 will be given in de-escalating doses (starting dose 16.8 mcg/kg, and de-escalated if needed to 12 mcg/kg, or 8 mcg/kg) every 4 weeks for 3 doses. Within 4 weeks after completing SBRT, those participants receiving immunotherapy agents will receive M9241 by subcutaneous injection at dose determined during the safety lead in every 4 weeks for 3 doses.

SBRT to the prostate will be delivered in 5 fractions of radiation each of 7.25-8.0 Gy, every other day over the course of 10 business days (2-3 weeks). The total dose will be 36.25-40 Gy