Immunoinformatics Approach to Design a Multi-Epitope Vaccine Targeting GPRC5D in Multiple Myeloma

Background Multiple myeloma (MM) is an incurable hematological malignancy characterized by clonal proliferation of plasma cells within the bone marrow. Despite advances in chemotherapy, monoclonal antibodies, and cellular therapies, MM remains associated with high relapse rates and poor long-term survival. The G protein-coupled receptor class C group 5 member D (GPRC5D) has recently emerged as a selective tumor antigen in MM, validated by the clinical success of GPRC5D-directed CAR-T and bispecific antibodies. Methods An immunoinformatics pipeline was applied to design a multi-epitope vaccine targeting GPRC5D. The GPRC5D sequence was retrieved from NCBI and analyzed for physicochemical properties (ProtParam). Cytotoxic T lymphocyte (CTL), helper T lymphocyte (HTL), and B-cell epitopes were predicted using NetCTL, IEDB, and BepiPred servers, respectively, and screened for antigenicity, allergenicity, and toxicity. Cytokine-inducing potential was evaluated using IFNepitope and IL4Pred servers. Selected epitopes were assembled with appropriate linkers and fused to human β-defensin-3 as an adjuvant. Structural modeling and refinement were performed with Robetta and GalaxyRefine, followed by validation with PROCHECK and ProSA-web. Molecular docking was conducted against Toll-like receptors (TLRs) and representative HLA alleles using ClusPro. Population coverage was assessed with the IEDB tool, and immune response simulations were conducted using C-ImmSim. Results ProtParam analysis revealed GPRC5D as a 345-amino acid protein with molecular weight 38.79 kDa, acidic pI (4.58), high aliphatic index (119.77), and positive GRAVY score (+0.698), consistent with thermostability and multi-pass hydrophobic topology. Epitope prediction identified multiple antigenic CTL, HTL, and B-cell epitopes, several of which were predicted to induce IFN-γ and IL-4 responses. Docking analysis demonstrated strong binding of the vaccine construct to TLR-2, TLR-4, and HLA alleles, supporting robust innate and adaptive immune activation. Population coverage exceeded 90% globally, while immune simulation predicted high antibody titers, strong T-helper cell activation, and sustained memory responses. Conclusions A rationally designed GPRC5D-based multi-epitope vaccine is proposed as a promising immunotherapeutic strategy in MM. While computational analyses demonstrate strong immunogenic potential, further in vitro and in vivo validation is required to establish translational applicability.