Safety of PSMA radioligand therapy in mCRPC patients with preexisting moderate to severe thrombocytopenia.

Aim of this study was to analyze the safety of prostate-specific membrane antigen radioligand therapy (PSMA-RLT) in patients with metastatic castration-resistant prostate cancer (mCRPC) with preexisting moderate to severe thrombocytopenia (CTCAE ≥ 2).

Seventeen mCRPC patients with preexisting thrombocytopenia (platelet count < 75 × 109/L) were included in this study. Patients received a median of 3 cycles of [177Lu]Lu-PSMA-617 (range 1-6). The course of platelet cell count was closely monitored within and after the PSMA-RLT and analyzed statistically and according to CTCAE.

No significant difference in platelet counts was observed between baseline and follow-up after each PSMA-RLT cycle: first cycle (54.18 ± 16.07 at baseline vs. 59.65 ± 39.16 at follow up [in × 109/L], p=  0.834), second cycle (58.56 ± 16.43 vs. 107.1 ± 56.44, p = 0.203), and third cycle (60.38 ± 16.57 vs. 132.1 ± 80.43, p = 0.148), respectively. Similarly, baseline and end of treatment values, irrespective of the number of administered cycles, did not reveal a significant difference (54.18 ± 16.07 vs. 72.06 ± 71.9, p = 0.741). After the end of therapy, irrespective of the number of administered cycles, 29.4% of patients remained stable in terms of CTCAE scoring, 41.2% changed to a higher score and 29.4% improved to a lower score. We observed no critical bleeding events due to thrombocytopenia.

Despite the common consideration of marked preexisting thrombocytopenia as a contraindication for RLT, this study indicates feasibility of PSMA-RLT in patients with preexisting thrombocytopenia of grade ≥ 2, as in our preliminary experience, there was no RLT-induced significant deterioration of platelet cell count. Thus, patients with thrombocytopenia should not be categorically excluded from receiving PSMA-RLT.

European journal of nuclear medicine and molecular imaging. 2024 Dec 03 [Epub ahead of print]

Moritz B Bastian, Maike Sieben, Arne Blickle, Caroline Burgard, Tilman Speicher, Mark Bartholomä, Andrea Schaefer-Schuler, Stephan Maus, Samer Ezziddin, Florian Rosar

Department of Nuclear Medicine, Saarland University, Kirrberger Str., Geb. 50, 66421, Homburg, Germany., Department of Nuclear Medicine, Saarland University, Kirrberger Str., Geb. 50, 66421, Homburg, Germany. .