SVV-001 With Nivolumab and Ipilimumab in Patients With Poorly Differentiated Neuroendocrine Carcinomas (NEC) or Well-Differentiated High-Grade Neuroendocrine Tumors (NET)

"SVV-001 will be administered intratumorally as a single dose on Day 1; or as multiple doses on Days 1, 15, 29, 43, 57, and 71. The virus dose levels per SVV-001 treatment are as follows:~* 2.2 × 10\^8 Viral Genomes (VG) (starting dose)~* 2.2 × 10\^9 VG~* 2.2 × 10\^10 VG"

Nivolumab will be administered via intravenous (IV) injection at a dose of 240 mg, once every two weeks starting on Day 15 until Day 85 during SVV-001 therapy. Nivolumab will be administered once every four weeks during the maintenance period for up to 2 years.

Ipilimumab will be administered via intravenous (IV) injection at a dose of 1 mg/kg, once every six weeks starting on Day 15 until Day 85 during SVV-001 therapy. Participants will continue on 1 mg/kg ipilimumab IV every 6 weeks for two additional doses or unacceptable toxicity and/or participant withdrawal.