Impact of pre-treatment hemoglobin (Hgb) on outcomes in metastatic castration resistant prostate cancer (mCRPC) with lutetium-177-PSMA-617 (Lu-177).

Abstract

e17065 Background: The Phase 3 VISION and TheraP trials excluded men with Hgb≤ 9 g/dL or blood transfusion within 30 days of Lu-177. Patients (pts) with mCRPC who are eligible for Lu-177 are often pancytopenic due to marrow infiltration and previous cytotoxic therapy. Clinicians are often faced with the dilemma of packed red blood cell (RBC) transfusion (Tx) to meet “eligibility requirements" of Lu-177. The impact of low Hgb levels on treatment (trt) outcomes is unclear. Methods: We retrospectively identified pts with mCRPC who received at least one cycle of Lu-177 between July 2022 and January 2023 at a single institution. Demographic, disease, laboratory and trt characteristics were recorded. Pts with Hgb level ≤10 g/dL or who received RBC Tx up to 14 days prior to the first Lu-177 dose were compared to pts with a pre-trt Hgb level ≥10 g/dL and no prior PRBC Tx. Data were summarized using descriptive statistics. Time to trt discontinuation was defined as the time from the first Lu-177 cycle until progressive disease per treating physician (clinical, radiographic, PSA progression) or adverse effect necessitating cessation and compared using the Kaplan Meier method. Cox proportional hazard regression analysis were utilized to assess the association of Hgb ≤ or ≥ 10 g/dL on the risk of trt discontinuation. Results: 51 pts were included, median follow up was 5.75 months, median age 70 years, 90% Caucasian. 49% (n = 25) had Gleason 9 /10 disease. Median number of prior trt was 4. 94% (n = 48), received prior docetaxel and 39% (n = 20) received prior cabazitaxel. 27% (n = 14) of pts had either Hgb≤10 or received a RBC Tx prior to trt. Of these, 50% of pts (n = 7) had stopped Lu-177 prior to completion of 6 cycles. Median number of cycles was 3. Reasons for trt cessation included clinical decline (n = 4), PSA or radiographic disease progression (n = 2), cytopenia (n = 1). Of pts who had Hgb ≥10 (n = 37), most (86%) are in ongoing trt, 11% (n = 4) have stopped trt due to progressive disease, 1 pt died. Pts with Hgb≤10 had a shorter time to trt discontinuation, 4.5 months (95% CI: 4.43- NA) vs not reached for those with Hgb≥10, p = 0.004 and an increased risk of trt discontinuation HR = 1.65 (95% CI: 1.53-18.09, p = 0.009). Conclusions: Pre-trt Hgb≤10 g/dL may be associated with worse outcomes in pts with mCRPC undergoing trt with Lu-177 and caution should be exercised. A larger data set and longer follow up is needed to further investigate outcomes in this pt population. Multivariable analysis is planned. [Table: see text]