Efficacy and safety of concomitant 177Lu-DOTATATE and low-dose capecitabine in advanced medullary thyroid carcinoma: a single-centre experience.

Peptide receptor radionuclide therapy (PRRT) has been shown to be useful in inoperable/metastatic medullary thyroid carcinoma (MTC). However, the role of concomitant PRRT and low-dose capecitabine therapy has not yet been studied in these patients. This study was conducted to evaluate the efficacy and safety of this combination approach in advanced MTC. This was a retrospective, single-centre study. Data of consecutive patients of advanced inoperable/metastatic MTC treated with concomitant Lu-DOTATATE+capecitabine, from January 2014 to August 2018, were collected and analysed for radiological, molecular and biochemical responses and treatment-related toxicity. Eight patients with advanced MTC received a median cumulative dose of 20.9 GBq (interquartile range 8.9-27.7 GBq) Lu-DOTATATE over 1-4 cycles and 1250 mg/m capecitabine from days 0 to 14 of each PRRT cycle. Radiological response according to Response Evaluation Criteria in Solid Tumours 1.1 criteria could be assessed in seven patients. Six out of seven patients (86%) had stable disease, while disease progression was observed in 1/7 (14%) patients. However, molecular response, as per the European Organization for Research and Treatment of Cancer criteria, was observed in all the seven patients. Biochemical response with reduction in serum calcitonin levels was observed in 3/5 (60%) patients. With the exception of grade 2 anaemia in one patient, no other significant toxicity was observed in this cohort. Our results indicate the efficacy and safety of concomitant Lu-DOTATATE and capecitabine in advanced MTC. Larger randomized controlled trials are, however, required to establish the role of capecitabine as a radiosensitizer along with PRRT in these patients.