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

Inclusion Criteria:

1. Male or female patients, 18 years of age or older at the time of consent.

2. Life expectancy of 6 months or greater as assessed by the treating oncologist.

3. Have advanced metastatic disease that has progressed on at least one line ofavailable therapy.

4. Histologically or cytologically confirmed diagnosis of Grade 3 well-differentiatedneuroendocrine tumor (NET) or poorly differentiated neuroendocrine carcinoma (NEC;large-cell neuroendocrine carcinoma, small-cell carcinoma, mixed neuroendocrine nonneuroendocrine carcinoma). Note: if an archival tissue sample collected ≤ 2 yearsfrom enrollment is unavailable at Screening for diagnostic confirmation, at thePrincipal Investigator's (PI's) discretion, a screening biopsy will be ordered.

5. For patients in Part 1A, in addition to histological or cytological confirmation ofNEC or NET (see Inclusion #4), radiological confirmation of tumor is required.

6. Parts 1B and 2 only: Measurable disease as determined by Response EvaluationCriteria in Solid Tumors (RECIST) v1.1 or immune-related Response EvaluationCriteria in Solid Tumors (iRECIST). At least one lesion must be suitable formultiple injections (up to 6 injections every 2 weeks) with SVV-001. Lesions forinjection must be ≥10 mm and ≤50 mm in longest diameter and deemed safe and suitablefor injection by the Investigator.

7. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.

8. Recovered to Grade 1 or baseline from any clinically significant toxicity associatedwith prior treatments (excluding alopecia) prior to initiation of investigationalmedicinal product (IMP) administration.

9. Adequate hematological, renal, and liver function defined as follows:

• a. Hepatic:

• i. Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤2.5 × upper limit of normal (ULN) (≤5 × ULN if liver metastases arepresent)

• ii. Serum bilirubin ≤1.5 × ULN (unless due to Gilbert's syndrome orhemolysis)

• b. Renal:

• i. Creatinine clearance ≥50 mL/minute using Cockcroft Gault equation

• c. Hematologic:

• i. Absolute neutrophil count ≥1500 cells/µL

• ii. Platelet count ≥100,000 platelets/µL

• iii. Hemoglobin ≥9.0 g/dL

• iv. International normalization ratio (INR) within the institutionalnormal range

• v. Normal prothrombin time (PT) and partial thromboplastin time (PTT)

10. For Part 2 Expansion Cohort patients only, patients will submit archival tissue atScreening and undergo a post-treatment biopsy according to the treatinginstitution's guidelines with the following exceptions:

• a. If an archival tissue sample collected ≤ 2 years from enrollment isunavailable at Screening, at the PI's discretion, a screening biopsy will beordered.

• b. Participants will not undergo a biopsy procedure for collection of thepost-treatment biopsy if, in the discretion of their treating physician, theparticipant's condition has deteriorated to the point where performance of abiopsy procedure would place the participant at an increased risk forcomplications beyond what is reasonably expected for a biopsy collected as partof the participant's standard medical care.

11. Women of childbearing potential must agree to use a reliable form of contraceptiveduring the trial treatment period and for at least 7 months following the last doseof IMP.

12. Male patients must agree to use an adequate method of contraception during the trialtreatment period and for at least 7 months following the last dose of IMP.

13. Patient is willing and able to comply with all protocol-required assessments,visits, and procedures.

14. Provide written informed consent prior to performing any trial-related procedure.

Exclusion Criteria:

1. Any active second malignancy within the 2 years prior to the screening visit, unlessthe patient has undergone curative surgery for the tumors such as in situ cervicalcancer or squamous cell cancer of the skin.

2. Has had cytotoxic chemotherapy or radiation therapy within 3 weeks; and less than 5half-lives or 6 weeks, whichever is shorter, from prior biologic therapies, prior tothe first dose of SVV-001.

3. Has undergone a major surgical procedure (as defined by the Investigator) orsignificant traumatic injury within 28 days prior to the first dose of SVV-001.

4. Has any physical abnormality of the tissue/organ to be biopsied that would put thepatient at increased risk of bleeding secondary to the injection and/or biopsy.

5. Has received a live-virus immunization within 30 days prior to the screening visitor anticipates receiving a live virus immunization during the trial or within 30days of the last treatment with IMP.

6. Presence of an active autoimmune or inflammatory disease requiring systemictreatment within the past 2 months or a documented history of clinically severeautoimmune disease that requires systemic steroids or other immunosuppressivemedications. Local steroid injections, intermittent use of topical, inhaled,ophthalmologic, intra-articular, or intranasal corticosteroids, or systemiccorticosteroids at physiologic doses not to exceed 10 mg/day of prednisone orequivalent would not result in exclusion from the trial.

7. Presence of primary immunodeficiency or receiving systemic steroids of >10 mg/dayprednisone or equivalent or other immunosuppressive agents within 14 days prior tothe first dose of SVV-001.

8. Any active infection, including known infection with human immunodeficiency virus (HIV), active hepatitis, or seropositive for hepatis B immunoglobulin (Ig) M coreantibody or hepatitis C ribonucleic acid (RNA) at the screening visit.

9. Patients with a history of solid-organ or bone marrow transplant.

10. Known hypersensitivity to ipilimumab or nivolumab or their excipients

11. Has known untreated central nervous system metastases. Patients with treated brainmetastases are eligible as long as they are stable and there is no evidence ofprogression for at least 4 weeks after central nervous system-directed treatment, asascertained by clinical examination and brain imaging (magnetic resonance imaging (MRI) or computed tomography (CT)) during the screening period.

12. Any clinically significant (i.e., active) cardiovascular disease, including cerebralvascular accident/stroke (<6 months prior to enrollment), myocardial infarction (<6months prior to enrollment), unstable angina, congestive heart failure (≥ New YorkHeart Association Classification Class II), or serious cardiac arrhythmia requiringmedication.

13. Patients with an ejection fraction (EF) < 50 on a 2D echocardiogram (ECHO).

14. Patients whose baseline pulse oximetry (saturation of peripheral oxygen (SpO2)) is < 92% on Room air.

15. Any chronic illness, psychiatric condition, or social situation that is lifethreatening or, in the opinion of the Investigator, renders the patient unsuitablefor participation in a clinical trial due to possible noncompliance or would placethe patient at an unacceptable risk and/or have the potential to affectinterpretation of the results of the trial.

16. Female participants who are breastfeeding and/or who have a positive pregnancy testresult prior to receiving any treatment with IMP.

17. Patients with impaired decision-making capacity.