Faculty Bibliography

BACKGROUND: In the development of an antimelanoma vaccine, a critical factor is the identification of antigens that induce a strong immune response in humans and that are expressed by melanoma cells in vivo. The aim of this study was to identify candidate antigens for such vaccine. METHODS: Sixty-nine patients with surgically resected melanomas (American Joint Commission on Cancer [AJCC] stage III) were immunized with a polyvalent vaccine containing multiple melanoma antigens. Antimelanoma antibodies generated in the patients' sera were used as probes to identify the melanoma antigens that are immunogenic in humans and that are expressed on the tumor tissue in vivo. Such responses were determined by an immunoblotting assay that employed an antigen source prepared from membrane fractions of freshly excised melanoma tissue. RESULTS AND CONCLUSIONS: Vaccine treatment stimulated antibody responses in 35 (51%; 95% confidence interval [CI] = 39%-63%) of 69 sequentially enrolled patients. The antibodies were directed to one or more antigens with molecular masses of 45, 59, 68, 79, 89, 95, and/or 110 kd. The most immunogenic antigens were p110 and p68, which induced responses in 33% (95% CI = 22%-44%) and 25% (95% CI = 15%-35%) of patients, respectively. Both antigens were commonly expressed on different melanomas, but they were absent on autologous normal tissue and on an unrelated allogeneic tumor. All the above antigens are attractive candidates for vaccine construction

An important element in melanoma vaccine construction is to identify peptides from melanoma-associated Ags that have immunogenic potential in humans and are recognized by CD8+ T cells in vivo. To identify such peptides, we evaluated HLA-A*02+ melanoma patients immunized to a polyvalent vaccine containing multiple Ags, including MAGE-3, Melan-A/MART-1, gp100, tyrosinase, melanocortin receptor (MC1R), and dopachrome tautomerase (TRP-2). Using a filter spot assay, we measured peripheral blood CD8+ T cell responses, before and after immunization, to a panel of 45 HLA-A*0201-restricted peptides derived from these Ags. The peptides were selected for immunogenic potential based on their strong binding affinity in vitro to HLA-A*0201. Vaccine treatment induced peptide-specific CD8+ T cell responses to 22 (47.8%) of the peptides. The most striking finding was the HLA-independent heterogeneity of responses to both peptides and Ags. All responding patients reacted to different combination of peptides and Ags even though the responding patients were all A*0201+ and the peptides were all A*0201-restricted. From 9 to 27% of patients developed a CD8+ T cell response to at least one peptide from each Ag, but no more than 3 (14%) reacted to the same peptide from the same Ag. This heterogeneity of responses to individual peptides and Ags in patients with the same haplotype points to the need to construct vaccines of multiple peptides or Ags to maximize the proportion of responding patients

Treatment for metastatic melanoma is limited by low response rates to single- or combination-agent chemotherapy. Recent studies have examined the role of biologic modifiers and differentiating agents. This phase II study examined the efficacy and toxicity of combining alpha-2b-interferon (IFN alpha) and 13 cis retinoic acid (cRA) in the treatment of metastatic malignant melanoma. Thirteen patients were treated with IFN alpha (5 x 10(6) units/m2 three times weekly) and cRA (1 mg/kg per day). One patient with lung and adrenal metastases had a partial response 6 months in duration and two patients had stabilization of lung metastases for 2 months. All other patients had progressive disease. Toxicity was substantial with all patients experiencing Eastern Cooperative Oncology Group grade 1-2 fatigue, myalgias, anorexia, stomatitis, and cheilitis. In addition, serum cholesterol and triglycerides were elevated in all patients. Seven patients required 50% dose reductions because of hypertriglyceridemia, fatigue associated with a significant decline in performance status, and severe stomatitis with anorexia and weight loss. One patient discontinued therapy because of a decline in performance status. This study suggests this combination of cRA and IFN alpha is inactive in the treatment of metastatic melanoma and is associated with substantial toxicity

Single agent activity of vinorelbine in previously untreated breast cancer and its predictable toxicity make it ideal for combination with cisplatin, a drug we found to be very active in combination with paclitaxel (J Clin Oncol; 14:1993, 1996), but with a high rate of neurotoxicity limiting duration of therapy. Eligibility included: histologically proven locally advanced or metastatic measurable breast cancer, ECOG performance status (PS) of 2 or less, adequate organ function. Cisplatin was given at a dose of 75 mg/m2 on day 1, with vinorelbine 30 mg/m2 days 1 and 8 of a 21 day cycle; day 8 vinorelbine dose was modified for neutropenia and thrombocytopenia. 24 patients (pts) entered the study, of whom 23 were eligible and 1 too early for response evaluation. 20 pts were treated as first line therapy for advanced disease (10 locally advanced and 10 metastatic). 3 pts were treated as second-line therapy for metastatic disease. Median age was 49 (range 32-67), median ECOG PS = 0. Nine pts had prior adjuvant chemotherapy and 8 pts had prior RT. A total of 91 cycles of chemotherapy were given with a median of 3 per pt. Hematological toxicity included leukopenia gr 3 = 4 pts, gr 4 = 2; neutropenia gr 3 = 4, gr 4 = 7 pts; no gr 3 or 4 thrombocytopenia. Non-heme toxicity included: N/V gr 2 = 6 pts, gr 3 = 1; neuropathy gr 1 = 10; gr 2 = 2; renal gr 2 = 1 pt. Responses seen included 2 CRs and 6 PRs (of 9 evaluable) locally advanced, 1 CR and 5 PRs (of 10) in metastatic disease, and 1 CR + 1 PR (of 3) second line therapy. Overall response rate was 73% (4 CR + 12 PR + 4 SD = 18% CR and 55% PR) of 22 evaluable pts. These data suggest that combined vinorelbine/cisplatin therapy is highly active in locally advanced and metastatic breast cancer without the high incidence of dose-limiting neurotoxicity seen in our prior paclitaxel/cisplatin trial. Accrual is continuing to improve the 95% confidence interval. (C) American Society of Clinical Oncology 1997

A critical requirement to use tumor antigens as vaccines is that they stimulate CD8+ T cell responses. In this study, we tested the ability of a shed, polyvalent, melanoma antigen vaccine to induce such responses to the melanoma-associated antigens, MAGE-3 and MART-1/Melan-A. Fifteen HLA-A2+ patients with resected malignant melanoma were immunized to the vaccine sc every 2-3 weeks x 4, and monthly thereafter. CD8+ T cells in peripheral blood reacting to HLA-A2 restricted epitopes on MAGE-3 (FLWGPRALV) and/or MART-1/Melan-A (AAGIGILTV) were quantitated directly using a filter spot assay at baseline and following 4 immunizations. Vaccine immunization induced CD8+ T cells reacting specifically to one or both of these antigens in 9 (60%) patients. These cells were CD8+ and HLA-A2 restricted, as reactivity was abrogated by monoclonal antibodies to CD8 and to class I HLA, but not by anti-CD4. The CD8+ T cells were specifically directed to these antigens, as they did not react to the same targets pulsed with a control HLA-A2 restricted peptide recognized by T cells. All responding patients remained recurrence-free during a follow-up of 12-21 months, whereas melanoma recurred within 3-5 months in non-responders. The differences in outcome were unrelated to differences in disease-severity or overall immunological competence between CD8+ T cell responders and non-responders. These results demonstrate that a polyvalent vaccine can stimulate a CD8+ T cell response to MAGE-3 and MART-1/Melan-A in humans, and suggest that the responses are protective and surrogate markers of vaccine efficacy. (C) American Society of Clinical Oncology 1997