A Study of VAC85135, a Neoantigen Vaccine Regimen, Concurrently Administered With Ipilimumab for the Treatment of Myeloproliferative Neoplasms

Inclusion Criteria

• Be positive for a CALR (calreticulin) mutation: Type 1 or Type 2; Type 1-like, or Type 2-like may be considered with Sponsor approval; or positive for the JAK2V617F (Janus kinase 2 with valine 617 to phenylalanine mutation) mutation with HLA-A02:01 (human leukocyte antigens) per medical history or local testing
• Have an Eastern Cooperative Oncology Group (ECOG) performance status grade of 0 or 1 or 2
• Have the following hematologic laboratory values: Leukocytes greater than or equal to (>=) 1.5*10^9 per liter, Neutrophils >=1.0*10^9 per liter, Platelets >=20*10^9 per liter, Hemoglobin greater than (>) 7 gram per deciliter (g/dL)
• Have the following chemistry laboratory values: Alanine aminotransferase (ALT): less than or equal to (<=) 3*upper limit of normal (ULN), Aspartate aminotransferase (AST): <=3*ULN, Total bilirubin: <=1.5*ULN, and glomerular filtration rate >=40 milliliter per minute (mL/min)
• A female participant of childbearing potential must agree to all the following during the study and for 6 months after the last dose of study treatment: use a barrier method of contraception, use a highly effective preferably user-independent method of contraception, not to donate eggs (ova, oocytes) or freeze for future use for the purposes of assisted reproduction, not plan to become pregnant, not to breast-feed
• A male participant must agree to all the following during the study and for 90 days after the last dose of study treatment: wear a condom when engaging in any activity that allows for passage of ejaculate to another person, not to father a child, not to donate sperm or freeze for future use for the purpose of reproduction

Exclusion Criteria

• History of any significant medical condition per investigators judgment (example: severe asthma/chronic obstructive pulmonary disease (COPD), poorly regulated heart condition, insulin dependent diabetes mellitus)
• Serious known clinically relevant allergies or earlier anaphylactic reactions
• Currently pregnant or breastfeeding
• Prior treatment with any Janus kinase 1/2 (JAK1/2) inhibitor
• Known sensitivity or contraindications to the use of Ipilimumab per local prescribing information