Phase II RCT finds no benefit for adding capecitabine to 177Lu-Dotatate in advanced NETs

PURPOSE: Peptide receptor radionuclide therapy (PRRT) with [177Lu]Lu-[DOTA0,Tyr3]octreotate (177Lu-Dotatate) is an effective and safe treatment for patients with metastatic gastroenteropancreatic neuroendocrine tumors (GEP NET). Whereas 177Lu-Dotatate prolongs progression-free survival (PFS) and preserves quality of life (QoL), objective response rates (ORR) remain limited. Capecitabine, as a radiosensitizer, could increase efficacy without increasing 177Lu-Dotatate activity. This phase II randomized controlled trial investigated the additional cytotoxic or radiosensitizing effect of capecitabine in combination with 177Lu-Dotatate. PATIENTS AND METHODS: Patients with advanced somatostatin receptor-positive GEP NET or bronchopulmonary NET were scheduled to receive four cycles of 7.4 GBq 177Lu-Dotatate and capecitabine or 177Lu-Dotatate alone. Capecitabine (1,650 mg/m2/day) was administered for 2 weeks from the start of each PRRT cycle. Primary endpoints were ORR, PFS, and median overall survival (OS). Secondary endpoints included biochemical response, adverse events, and QoL. RESULTS: A total of 111 of the 200 predefined patients were randomized for 177Lu-Dotatate/capecitabine (n = 50) or 177Lu-Dotatate (n = 61). According to the intention-to-treat analysis, the ORR was 32% for the 177Lu-Dotatate/capecitabine group versus 46% for the 177Lu-Dotatate group (P = 0.348). Treatment with 177Lu-Dotatate/capecitabine did not prolong median PFS (45.7 vs. 31.7 months, P = 0.629) or median OS (75.8 vs. 61.4 months, P = 0.530). Quality-adjusted life years (QALY) were lower in the 177Lu-Dotatate/capecitabine group (1.30 ± 0.48 vs. 1.47 ± 0.48, P = 0.014). CONCLUSIONS: In this prematurely closed phase II study, 177Lu-Dotatate/capecitabine did not improve ORR or prolong PFS and OS in patients with advanced NET compared with 177Lu-Dotatate alone and was associated with reduced QALY.