CTLA-4 blockade enhances polyfunctional NY-ESO-1 specific T cell responses in metastatic melanoma patients with clinical benefit.

Blockade of inhibitory signals mediated by cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) has been shown to enhance T cell responses and induce durable clinical responses in patients with metastatic melanoma. The functional impact of anti-CTLA-4 therapy on human immune responses is still unclear. To explore this, we analyzed immune-related adverse events and immune responses in metastatic melanoma patients treated with ipilimumab, a fully human anti-CTLA-4 monoclonal antibody. Fifteen patients were selected on the basis of availability of suitable specimens for immunologic monitoring, and eight of these showed evidence of clinical benefit. Five of the eight patients with evidence of clinical benefit had NY-ESO-1 antibody, whereas none of seven clinical non-responders was seropositive for NY-ESO-1. All five NY-ESO-1 seropositive patients had clearly detectable CD4(+) and CD8(+) T cells against NY-ESO-1 following treatment with ipilimumab. One NY-ESO-1 seronegative clinical responder also had a NY-ESO-1 CD4(+) and CD8(+) T cell response, possibly related to prior vaccination with NY-ESO-1. Among five clinical non-responders analyzed, only one had a NY-ESO-1 CD4(+) T cell response and this patient did not have detectable anti-NY-ESO-1 antibody. Overall, NY-ESO-1-specific T cell responses increased in frequency and functionality during anti-CTLA-4 treatment, revealing a polyfunctional response pattern of IFN-gamma, MIP-1beta and TNF-alpha. We therefore suggest that CTLA-4 blockade enhanced NY-ESO-1 antigen-specific B cell and T cell immune responses in patients with durable objective clinical responses and stable disease. These data provide an immunologic rationale for the efficacy of anti-CTLA-4 therapy and call for immunotherapeutic designs that combine NY-ESO-1 vaccination with CTLA-4 blockade.

Safety and immunogenicity of tyrosinase DNA vaccines in patients with melanoma.

Immunity to self antigens on cancer is constrained by tolerance/ignorance. DNA vaccines encoding xenogeneic differentiation antigens, such as tyrosinase (TYR), mediate tumor protection and regression in implantable mouse models, and dogs with spontaneous melanoma. We conducted a trial of mouse and human TYR DNA vaccines in stage III/IV melanoma patients. Eighteen human leukocyte antigen (HLA)-A*0201(+) melanoma patients were randomized as follows: one group received three mouse TYR DNA injections followed by three human TYR DNA injections; the other group received the same vaccines in opposite sequence. The study was conducted at three dose levels: 100, 500, and 1,500 microg DNA/injection, administered intramuscularly (IM) every 3 weeks. Most toxicities were grade 1 injection site reactions. Seven patients developed CD8(+) T-cell responses, defined by a >3 SD increase in baseline reactivity to TYR peptide in tetramer or intracellular cytokine staining (ICS) assays. There was found to be no relationship between dose, assigned schedule, and T-cell response. At a median of 42 months follow-up, median survival has not been reached. Mouse and human TYR DNA vaccines were found safe and induced CD8(+) T-cell responses in 7 of 18 patients. T cells recognizing a native TYR peptide had a phenotype consistent with that of effector memory cells.