A Phase Ib Study of NeoVax in Combination With CDX-301 and Nivolumab or Pembrolizumab and in Patients With Melanoma

⁃ Eligibility to participate will be assessed at one timepoint: prior to initial core needle/surgical biopsy (Initial Registration).

• Inclusion Criteria

‣ Participant is willing and able to give written informed consent

⁃ Participants must have histologically confirmed stage IIIB/C/D or stage IV cutaneous melanoma (mucosal melanoma or uveal melanoma are excluded) that is surgically resected, is deemed surgically resectable, or is unresectable; tumor tissue for sequence analysis must be available from either previous melanoma resection/biopsy or at least one site of disease must be amenable to surgical or core biopsy

⁃ Age ≥ 18 years

⁃ ECOG performance status of 0 or 1

⁃ Recovered from all toxicities associated with prior treatment, to acceptable baseline status (as to Lab toxicity see below limits for inclusion) or a National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) version 5.0, Grade of 0 or 1, except for toxicities not considered a safety risk, such as alopecia or vitiligo

⁃ Participants must have normal organ and marrow function as defined below:

• WBC ≥3,000/µL

∙ ANC ≥1,500/µL

∙ Platelets ≥100,000/µL

∙ Hemoglobin ˃ 9.0 g/dL

∙ Total Bilirubin ≤ 1.5 x ULN (except subjects with Gilbert Syndrome, who can have total bilirubin \< 3.0 mg/dL)

∙ AST(SGOT)/ALT(SGPT) ≤ 3 x ULN

∙ Creatinine ≤ 1.5 x ULN OR

∙ Creatinine clearance ≥40 mL/min/1.73 m2 for participants with creatinine levels above institutional normal (if using the Cockcroft-Gault formula below):

⁃ Female CrCl = (140 - age in years) x weight in kg x 0.85 72 x serum creatinine in mg/dL

⁃ Male CrCl = (140 - age in years) x weight in kg x 1.00 72 x serum creatinine in mg/dL

• Women of childbearing potential (WOCBP) should have a negative serum pregnancy test (minimum sensitivity 25 IU/L or equivalent units of HCG) within 24 hours prior to the start of Nivolumab or Pembrolizumab, because the effects of NeoVax plus Montanide and Nivolumab (or Pembrolizumab) on the developing human fetus are unknown

• Because there is an unknown but potential risk for adverse events in nursing infants secondary to treatment of the mother with study agents, breastfeeding should be discontinued if the mother is treated Nivolumab or Pembrolizumab, Personalized Neoantigen vaccine, and CDX-301

• Female participants enrolled in the study, who are not free from menses for \>2 years, post hysterectomy / oophorectomy, or surgically sterilized, should be willing to use either 2 adequate barrier methods or a barrier method plus a hormonal method of contraception to prevent pregnancy or to abstain from sexual activity throughout the study, starting with visit 1 through 5 months after the last dose of study therapy. Approved contraceptive methods include for example: intra uterine device, diaphragm with spermicide, cervical cap with spermicide, male condoms, or female condom with spermicide. Spermicides alone are not an acceptable method of contraception. Should a woman become pregnant or suspect she is pregnant while she or her partner is participating in this study, she should inform her treating physician immediately.The investigational product will be permanently discontinued in an appropriate manner.

• Male participants should agree to use an adequate method of contraception starting with visit 1 through 7 months after the last dose of study therapy