A preparation of autologous CD8+ (cytotoxic) T-lymphocytes sensitized to cancer-testis antigen NY-ESO-1 antigen with potential immunostimulating and antineoplastic activities. Autologous CD8+ T-lymphocytes, isolated from a melanoma patient, are exposed to an NY-ESO-1 peptide ex vivo, expanded, and reintroduced into the patient; these tumor-reactive T-cells may stimulate a host immune response against tumor cells expressing the NY-ESO-1 antigen, resulting in tumor cell lysis. NY-ESO-1, an antigen found in normal testis, may be upregulated in various cancers, including bladder, breast, hepatocellular, melanoma, and prostate cancers.