Jonathan S. Cebon, Ian D Davis, Phillip Parente, Weisan Chen, Mark Shackleton, Wendie Hopkins, Heather Goldie, Eugene Maraskovsky, Qiyuan Chen, Heather Jackson, Tsin Yee Tai
Ludwig Institute for Cancer Research, Heidelberg, Australia

Grant McArthur
Peter MacCallum Cancer Institute, Melbourne, Australia

Duncan MacGregor, Sue Sturrock
Austin & Repatriation Medical Centre, Heidelberg, Australia

Simon Green, Andrew Cuthbertson, Darryl Maher, David Ryan, Michael McNamara, Debbie Drane, Lena Miloradovic 
CSL Limited, Melbourne, Australia,

Achim Jungbluth, Gerd Ritter, Elisabeth Stockert, Yao-T. Chen, Eric Hoffman, Sacha Gnjatic, Lloyd Old
Ludwig Institute for Cancer Research, New York, NY

A Phase 1 Clinical Trial of NY-ESO-1 Protein Formulated With Immunostimulatory Complexes (ISCOMÒ Adjuvant) in Patients with Minimal Residual Disease

Spontaneous antibody and cellular immune responses against the cancer testis antigen NY-ESO-1 occur in a subset of patients with NY-ESO-1 expressing tumors. NY-ESO-1 specific immune responses to injected HLA A2-restricted peptides of NY-ESO-1 have also been reported in patients with spontaneous NY-ESO-1 immunity. Furthermore, a number of Class-II epitopes to NY-ESO-1 presented on HLA DP4, DR53 and DR4 have been identified. The potential to stimulate both CD8+ and CD4+ T-cell responses following vaccination with full-length NY-ESO-1 protein formulated with ISCOMÒ
(ImmunoStimulating COMplexeS, CSL Ltd, Australia) adjuvant was pursued in a Phase 1 study. The ISCOMÒ adjuvant is saponin-based and has been shown to stimulate antibody responses and induce T helper cell as well as cytotoxic T lymphocyte responses in a variety of animal models and human clinical trials. The objectives of the current study were to evaluate the safety and immunogenicity of an NY-ESO-1 ISCOMÒ vaccine.

Forty-six (46) patients with minimal residual disease and tumors that expressed NY-ESO-1 antigen by immunohistochemistry and/or RT-PCR were evaluated in the study. Patients received NY-ESO-1 ISCOMÒ or protein alone, administered IM on three occasions at monthly intervals. NY-ESO-1 ISCOMÒ protein doses were: 10mg (n=3), 30mg (n=3), and 100mg (n=20). A further 20 patients received 100mg NY-ESO-1 protein alone. All patients except 10 in each of the 100mg groups were HLA-A2 positive, and 2 patients in each group of 10 received placebo.

Patients were evaluated for toxicity each week. Immune function was assayed in all patients by Delayed Type Hypersensitivity (DTH) to NY-ESO-1 protein alone and by NY-ESO-1 antibody titre (ELISA). In HLA-A2 patients the number of reactive NY-ESO-1 CD8+ T cells was measured by HLA-A2 tetramers and by “Cytospot assay” for g-interferon production. Results: Grade 3 injection site pain occurred in three patients who received 100mg. Grade 2 injection site pain, flu-like symptoms, fever and malaise were also noted, otherwise the vaccine was generally very well tolerated. At the 100mg dose of the NY-ESO-1 ISCOMÒ vaccine, enhanced DTH reactions (up to 60mm redness and 25mm induration) over baseline occurred. Antibody titres were significantly higher (>1:100,000) in patients immunized with ISCOMÒ formulation than with NY-ESO-1 protein alone. CD8+ cellular immune responses were observed in one of three NY-ESO-1 ISCOMÒ patients at the 10mg dose (a patient with prior antibody response), and otherwise at the 100 mg dose, primarily in patients who received the vaccine with adjuvant. There was a good correlation between tetramer and cytospot findings but little or no correlation between DTH and the monitored ESO1b-specific CD8+ T-cell responses. One patient has shown evidence of a response to a new peptide epitope presented on HLA DR2. This patient also had evidence of a simultaneous response to epitopes presented on HLA A2 and HLA DP4.

Conclusion: NY-ESO-1 ISCOMÒ vaccine was safe, well tolerated and generated both humoral and cellular NY-ESO-1 specific responses. Future studies will focus on identifying responses to other epitopes as well as undertaking trials in patients with evaluable disease to immune and clinical responses.