Eleven proven NETs patients with baseline FDG & Ga-68 DOTATATE PET/CT scans, interim and post-therapy Ga-68 DOTATATE scan (except in one patient) and tumor specific markers received minimum 4 cycles of Lu-177 DOTATATE along with low-dose capecitabine. Four patients did not receive capecitabine in first cycle of PRRT and two of them did not have for their second cycle also. RECIST 1.1 criteria, percent change in SUVmax in target lesions (∆sigma SUVmax) and tumor SUVmax to spleen SUVmax ratio (∆sigma TS ratio) along with clinical response and tumor markers were analysed to define non-responder and responder.

RECIST 1.1 showed 9 responder out of 10 (couldn’t be applied in one patient), both functional parameters (∆sigma SUVmax and ∆sigma TS ratio) showed response in 8/10 patients. Concordant results were seen comparing RECIST 1.1 in 8 and 7 patients with ∆sigma SUVmax and ∆sigma TS ratio in interim analysis. In data for 10 patients at end treatment, 8 were responder on RECIST 1.1 criteria, functional response were seen in 4/10 and 7/10 patients on basis of ∆sigma SUVmax and ∆sigma TS ratio. Clinical response and fall/ stable tumor markers were almost similar in interim and end of treatment period. Concordance was seen in 6/9 patients when the ∆sigma TS ratio were taken at interim and at end of treatment. One patient had vomiting in single cycle of PRRT. One and two patients had diarrhoea and stomatitis. Two patients showed grade-2 renal dysfunction. Eight patients had grade1-4 anaemia. Seven and five patients had grade1-2 leukopenia and grade1-2 thrombocytopenia that resolved in majority after treatment. 10/11 patients are alive at present with median period of 19 months (14-27 months).

TS ratio is shown to be a better functional imaging biomarker for therapy response assessment. PRRNT with capecitabine is safe and efficacious treatment modality.