Safety profile and therapeutic efficacy of one cycle of Lu177 PSMA in end stage metastatic castration resistant prostate cancer patients with low performance status

Introduction: Prostate cancer patients with distant metastasis have a poor prognosis and developed resistance to all standard drugs at various time intervals. A therapeutic option which can alleviate symptoms and prolong survival is in-search for these patients. Lu177 prostate specific membrane antigen (Lu177 PSMA) is a novel drug based on the theranostic concept. Here, we have presented the safety and efficacy profile of one cycle of Lu177 PSMA in metastatic castration resistant prostate cancer (mCRPC) patients who have exhausted all standard therapeutic options. Methods: Twenty-two patients treated with at least first line anti-androgens and docetaxel were treated with one cycle of Lu177 PSMA therapy on a compassionate basis. Haemoglobin, total leukocyte counts, platelets and serum creatinine for toxicity profile while prostate specific antigen (PSA), eastern cooperative oncology group (ECOG) performance status, visual analogue scale (VAS) and analgesic quantification scale (AQS) for therapeutic efficacy were recorded pre and 8 weeks post-therapy. Wilcoxon signed-rank and ANOVA tests were used for statistical analysis. Results: Partial response (PR), stable disease (SD) and progressive disease (PD) for PSA were seen in 5 (22.7%), 13 (59.1%) and 4 (18.2%) patients respectively treated with mean 6.88GBq dose of Lu177 PSMA. 8/22 (36.4%) patients showed ≥ 30% drop in PSA. Grade 3 haemoglobin toxicity was seen in 5/22 (22.7%) patients. No patient developed grade 4 haemoglobin toxicity. No patients had grade 3 or 4 leukocytopenia or thrombocytopenia. Wilcoxon signed-rank test showed statistical significant (p 0.05). ANOVA test showed a statistically significant difference in mean doses of Lu177 PSMA used in three PSA response group while the difference was non-significant for other variables. Conclusions: We concluded that Lu177 PSMA therapy has adequate pain palliation in all end-stage mCRPC patients and it has the potential to become an effective therapeutic option in properly selected patients.