Saad, Fred

5048 Background: Ra-223, an alpha-emitting radionuclide, is the first agent of its kind approved for the treatment of mCRPC. Although a pivotal phase 3 study evaluated its short-term safety, there is a need to investigate its long-term safety. The REASSURE study prospectively examined the long-term safety of Ra-223, including secondary primary malignancies (SPMs), in a large patient (pt) population enrolled across Europe, the United States, Israel, and Latin America. Methods: We report final analyses (data cut-off Oct 24, 2024) of REASSURE (NCT02141438), a global, noninterventional study (enrolment 2014–2017). Primary outcomes were the incidence of SPMs, short- (30 days) and long-term (7 years) safety events, and bone marrow suppression (BMS) management in pts who had ≥1 Ra-223 dose. Secondary outcomes included overall survival (OS). Results: Analyses included 1472 pts; median follow-up was 17 months (range 0.3–95.4). Median age was 73 years and 80% of pts had an ECOG PS of 0/1. In evaluable pts, median alkaline phosphatase, prostate-specific antigen, and lactate dehydrogenase levels were 133 U/L, 59 ng/mL, and 266 U/L, respectively. Overall, 81% of pts had bone-only metastases at baseline; 19% of pts had metastases in the bone plus other sites (mostly lymph nodes). Prior treatments included abiraterone (48% of pts), enzalutamide (39%), docetaxel (39%), and cabazitaxel (9%). Pts received a median of 6 Ra-223 doses; 67% received ≥5 doses. SPMs occurred in 2% of pts (25 SPMs in 24 pts). Of these pts, 16 (67%) and 1 (4%) had received prior or concomitant radiotherapy, respectively. Overall, 3% of pts had drug-related serious adverse events >30 days after completing Ra-223. Fractures were reported in 10% of pts and were less common in pts with (7% of 605) than without (12% of 867) concomitant BHA use. During Ra-223 and up to 30 days after the last dose, there was no notable difference in the incidence of abnormal platelet counts between pts with (3%) or without (2%) prior chemotherapy; similar findings were seen for abnormal neutrophil counts (5% and 5%, respectively). BMS treatments, assessed from the start of Ra-223, were more common in pts who had received prior taxanes (38%) than in those who had not (26%). The most common life-prolonging therapies received after Ra-223 were docetaxel (18%), enzalutamide (15%), abiraterone (11%), and cabazitaxel (11%). Median OS was 15.6 months (95% CI, 14.6, 16.4); pt subgroups that survived the longest will be characterized and presented. Conclusions: This real-world safety analysis of pts with mCRPC is the longest follow-up of a radiopharmaceutical reported to date and supports the well-established favorable safety profile of Ra-223. The incidence of SPMs was low. The rate of fracture was low, especially in the presence of BHAs. Prior taxane chemotherapy use had no impact on hematological toxicity. Clinical trial information: NCT02141438 .

TPS294 Background: Approval of [ 177 Lu]Lu-PSMA-617 ( 177 Lu-PSMA-617) for the treatment of adult patients with prostate-specific membrane antigen (PSMA)-positive metastatic castration-resistant prostate cancer, previously treated with androgen receptor pathway inhibitors and taxane-based chemotherapy, was based on the results of the Phase 3 VISION study (NCT03511664). It is important to further characterize long-term safety outcomes in 177 Lu-PSMA-617–treated patients, with particular regard to potential treatment-related risks. To this end, the long-term follow-up (LTFU) safety study (NCT05803941) has been established. Findings from the LTFU study will be crucial for assessing delayed toxicities for patients with PSMA-positive metastatic prostate cancer treated with 177 Lu-PSMA-617 globally. Methods: The LTFU study is a prospective, multi-center, non-EU post-authorization safety study. Patients who received ≥1 dose of 177 Lu-PSMA-617 within one of the prospective parent studies (Table 1) are eligible. Patients may enroll in the LTFU study after fulfilling the requirements of their corresponding parent study. The primary endpoint is the number and proportion of selected adverse events (AEs), including myelosuppression, xerostomia, renal failure, xerophthalmia, and second primary malignancies (eg, myelodysplastic syndrome or acute myeloid leukemia), other serious AEs, and changes in laboratory values. The secondary endpoint is the number and proportion of deaths. Following enrollment, patients will undergo assessments at baseline, and then every 6–8 months for up to 10 years after their first dose of 177 Lu-PSMA-617 or until death. At each visit, a review of selected treatment-related AEs (xerostomia, xerophthalmia, myelosuppression), any-cause AEs (renal toxicity, new diagnoses of second primary malignancies), and treatment-related serious AEs will be conducted. Physical and laboratory assessments, as well as details on concomitant medications and interventions, including anti-cancer therapies, will be collected. Patients may receive treatment with any medical intervention. Interim analyses are planned at 2 and 5 years post-study activation. Enrollment is ongoing (n=13). Clinical trial information: NCT05803941 . Parent studies of the long-term follow-up safety study. Trial Indication Phase N (all groups) ClinicalTrials.gov ID VISION (+sub-study) Post-taxane mCRPC 3 831 (+30) NCT03511664 PSMAfore Pre-taxane mCRPC 3 469 NCT04689828 PSMAddition mHSPC 3 1144 NCT04720157 177 Lu-PSMA-617 in patients with moderately or severely impaired, or normal renal function Post-taxane mCRPC 2 20 a NCT06004661 a Planned. mCRPC, metastatic castration-resistant prostate cancer; mHSPC, metastatic hormone-sensitive prostate cancer.

Purpose Ipilimumab increases antitumor T-cell responses by binding to cytotoxic T-lymphocyte antigen 4. We evaluated treatment with ipilimumab in asymptomatic or minimally symptomatic patients with chemotherapy-naive metastatic castration-resistant prostate cancer without visceral metastases. Patients and Methods In this multicenter, double-blind, phase III trial, patients were randomly assigned (2:1) to ipilimumab 10 mg/kg or placebo every 3 weeks for up to four doses. Ipilimumab 10 mg/kg or placebo maintenance therapy was administered to nonprogressing patients every 3 months. The primary end point was overall survival (OS). Results Four hundred patients were randomly assigned to ipilimumab and 202 to placebo; 399 were treated with ipilimumab and 199 with placebo. Median OS was 28.7 months (95% CI, 24.5 to 32.5 months) in the ipilimumab arm versus 29.7 months (95% CI, 26.1 to 34.2 months) in the placebo arm (hazard ratio, 1.11; 95.87% CI, 0.88 to 1.39; P = .3667). Median progression-free survival was 5.6 months in the ipilimumab arm versus 3.8 with placebo arm (hazard ratio, 0.67; 95.87% CI, 0.55 to 0.81). Exploratory analyses showed a higher prostate-specific antigen response rate with ipilimumab (23%) than with placebo (8%). Diarrhea (15%) was the only grade 3 to 4 treatment-related adverse event (AE) reported in ≥ 10% of ipilimumab-treated patients. Nine (2%) deaths occurred in the ipilimumab arm due to treatment-related AEs; no deaths occurred in the placebo arm. Immune-related grade 3 to 4 AEs occurred in 31% and 2% of patients, respectively. Conclusion Ipilimumab did not improve OS in patients with metastatic castration-resistant prostate cancer. The observed increases in progression-free survival and prostate-specific antigen response rates suggest antitumor activity in a patient subset.