Efficacy and safety of 225Ac-DOTATATE targeted alpha therapy in metastatic paragangliomas: a pilot study.

PURPOSE: In this study, we aim to evaluate the efficacy and safety of 225AC-DOTATATE targeted alpha therapy in advanced-stage paragangliomas (PGLs). METHODS: Nine (6 males and 3 females) consecutive patients with histologically proven PGLs were treated with 225Ac-DOTATATE targeted alpha therapy (TAT) and concomitant radiosensitizer, capecitabine, at 8-weekly intervals up to a cumulative activity of ~ 74 MBq. The primary endpoint included evaluating therapy response and disease control rate (DCR) using the RECIST 1.1 criteria. Additional secondary endpoints comprised clinical response assessment using EORTC QLQ-H&N35 questionnaire, Karnofsky Performance Scale (KPS), Eastern Cooperative Oncology Group performance status (ECOG), analgesic score (AS), dose alterations of anti-hypertensive drugs (anti-HTN), and the safety and side-effect profile evaluation as per CTCAE criteria version 5.0. RESULTS: Following 225Ac-DOTATATE treatment, morphological response revealed partial response in 50%, stable disease in 37.5%, and disease progression in 12.5%, with a DCR of 87.5%. Similarly, the symptomatic response was remarkable, and anti-HTN drugs were stopped in 25% and reduced in 37.5%. Another significant finding in our study revealed a morphologic DCR of 66.6% (2/3) in patients who failed previous lutetium-177 peptide receptor radionuclide therapy (177Lu-PRRT). Regarding the KPS, ECOG, and AS performance scores, a notable improvement was observed post-225Ac-DOTATATE treatment. The QLQ-H&N35 symptom scores evaluated in seven H&N PGL patients showed significant improvement in all aspects. No improvement in sexual function was noted (P = 0.3559). Despite the significant reduction in the analgesic score post-treatment (P = 0.0031), the QLQ-H&N35 revealed only marginal significance concerning the intake of pain killers (P = 0.1723). No grade III/IV hematological, renal, and hepatological toxicities were noted. CONCLUSION: The evidence from this study suggests 225Ac-DOTATATE therapy is effective and safe in the treatment of advanced-stage PGLs and also reports a clear benefit even in patient's refractory to the previous 177Lu-PRRT.

Broadening horizons with 225Ac-DOTATATE targeted alpha therapy for gastroenteropancreatic neuroendocrine tumour patients stable or refractory to 177Lu-DOTATATE PRRT: first clinical experience on the efficacy and safety.

PURPOSE: The objective of this study was to investigate and present the early results on the efficacy, safety, and quality of life of 225Ac-DOTATATE targeted alpha therapy (TAT) in patients with advanced, progressive, 177Lu-DOTATATE refractory, and somatostatin receptor (SSTR) expressing metastatic GEP-NETs. METHODS: In this prospective study, we recruited patients with metastatic GEP-NETs who were stable or progressive disease on 177Lu-DOTATATE therapy. Systemic TAT using 225Ac-DOTATATE was performed in all the patients with 225Ac-DOTATATE (100 kBq/kg body weight) at an interval of 8 weeks. The primary end point was to assess the objective response (measured by RECIST 1.1 and functional M.D. Anderson criteria). The secondary end points included biochemical response assessment as per the Italian Trials in Medical Oncology (ITMO), adverse event profile as per CTCAE v5.0, and clinical response assessment by the quality of life (assessed with EORTC QLQ-GI.NET21 patient-based questionnaire). RESULTS: Between April 2018 and March 2019, 32 patients (17 females, 15 males, mean age 52 ± 9.2 years, 35-72 years) with either stable disease after completing 177Lu-DOTATATE therapy (14, 44%) or progressive disease on 177Lu-DOTATATE therapy (18, 56%) were included in the study. The morphological response was assessed in 24/32 patients that revealed partial remission in 15 and stable disease in 9. There was no documented disease progression or deaths in the median follow-up of 8 months (range 2-13 months). There was a significant decrease in the plasma chromogranin level post-225Ac-DOTATATE therapy (P < 0.0001). CONCLUSION: Our short-term clinical results indicate 225Ac-DOTATATE TAT as a promising treatment option which adds a new dimension in patients who are refractory to 177Lu-DOTATATE therapy or have reached the maximum prescribed cycles of 177Lu-DOTATATE therapy.