Background: Metastatic neuroendocrine neoplasms (mNEN’s) originating in the gastrointestinal tract are frequently slow growing yet both symptom and disease control remain important. Treatment options include resection, chemoablation, systemic somatostatin analogues (SSA) or peptide receptor radionuclide therapy (PRRT), but additional options are needed and one such option is hepatic intralesional (IL) rose bengal disodium (PV-10), an oncolytic immunotherapy under development for solid tumours. Methods: This phase 1 study is evaluating the safety, tolerability and reduction of biochemical markers and symptoms resulting from percutaneous administration of PV-10 in 12 subjects with progressive mNEN with hepatic lesions not amenable to resection or other potentially curative therapy. Target lesion(s) must be 1.0 - 3.9 cm in longest diameter. In Cohort 1 (n = 6) subjects receive PV-10 to a single hepatic lesion per treatment cycle, and can receive PV-10 to additional uninjected hepatic lesions ≥6 weeks after prior injection. Cohort 2 (n = 6) subjects may receive injection of multiple lesions per treatment cycle. The primary endpoint is safety. Secondary endpoints include objective response rate (ORR) assessed by contrast enhanced CT and ⁶⁸Ga-DOTATATE PET, biochemical response (CgA) and patient-reported outcome (EORTC QLQ-C30 and GI.NET21). Results: Cohort 1 has fully enrolled, with 4 of 6 subjects male, median age 65yrs, range 47-72. Primary sites were: small bowel 3, pancreas 2, caecal 1; grade: Gd1 = 5, Gd2 = 1. All patients received prior SSA and PRRT. Median CgA was 645 (range 30-2819). To date 1 subject has received 4 PV-10 treatment cycles, 1 has received 2 cycles, and 4 have received a single cycle. Toxicity has been acceptable, including pain post procedure, carcinoid flare and nausea. LFT’s have remained stable. Overall QOL score was stable for 5 of 6 subjects. ORR in injected lesions is 50% (progression in 1 subject), with overall disease control of 84%. CgA response: 5 stable, 1 progression. One subject with “carcinoid pellagra” had rash resolution. Response follow-up is ongoing and additional efficacy and functional data will be presented. Conclusions: Hepatic IL PV-10 elicited no safety concerns with encouraging evidence of both local and systemic disease control. Enrolment to Cohort 2 is underway. Clinical trial information: NCT02693067