Identification of melanoma antigens that are immunogenic in humans and expressed in vivo.

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.

Modulation of monocyte functions by muramyl tripeptide phosphatidylethanolamine in a phase II study in patients with metastatic melanoma.

BACKGROUND: Muramyl tripeptide phosphatidylethanolamine (MTP-PE) is a synthetic analogue of muramyl dipeptide (MDP), a component of bacterial cell walls that has potent in vitro monocyte-activating properties. We conducted a phase II clinical trial of MTP-PE in 30 patients with metastatic melanoma. PURPOSE: Our purpose was to define a clinical response rate for this agent in patients with advanced melanoma and to evaluate the agent's immunomodulatory properties. METHODS: Patients were randomly assigned to 1- or 4-mg dose levels of MTP-PE and received the drug intravenously once a week for 12-24 weeks. Immunological monitoring consisted of measurement of plasma tumor necrosis factor-alpha (TNF-alpha), neopterin, interleukin-1-beta, interleukin-6 (IL-6), and beta 2-microglobulin levels; phenotyping analysis of expression of human HLA-DR, CD-14 on mononuclear cells; and measurement of in vitro monocyte cytotoxicity against SKMel28 targets cells. RESULTS: MTP-PE was well tolerated; fever and chills were the major toxic effects. Plasma TNF-alpha levels increased 16-fold 2 hours after the first MTP-PE treatment. Increases in TNF-alpha levels after MTP-PE administration continued through week 12, but changes were of a lower magnitude after week 1. Plasma neopterin levels were significantly increased 24 hours after treatment at weeks 1, 6, and 12. A marked increase in IL-6 and a modest rise in beta 2-microglobulin levels were also seen at week 1. No significant changes from baseline IL-1 beta were observed. In the cytotoxicity assay, monocyte cytotoxic activity was significantly increased at weeks 4 and 6. Surface immuno-phenotyping revealed a consistent transient reduction in the number of circulating monocytes 2 hours after MTP-PE was administered. In addition, we observed a down-regulation (i.e., a decrease) in the expression of Leu M3 and HLA-DR on monocytes, 2 hours after MTP-PE treatment, followed by a recovery 24 hours after treatment. No objective clinical responses were seen in this advanced disease population. CONCLUSIONS: We conclude that MTP-PE has pleiotropic and potentially beneficial biologic effects and that further clinical investigations of MTP-PE are justified. IMPLICATIONS: In view of the clear immunomodulatory actions seen in our study and in earlier clinical trials, we believe that MTP-PE deserves further study in the adjuvant setting.

Pharmacokinetics of the cardioprotector ADR-529 (ICRF-187) in escalating doses combined with fixed-dose doxorubicin.

BACKGROUND: Although doxorubicin is an anticancer agent with a wide spectrum of activity, therapy with this anthracycline must often be discontinued at a time of benefit to the patient because of the drug's cumulative cardiotoxicity. ICRF-187 (ADR-529, dexrazoxane) is a bisdioxopiperazine compound that protects against cardiac toxicity induced by doxorubicin. PURPOSE: Our objectives in this study were to determine the maximum tolerated dose of ADR-529 (which uses a different vehicle than ICRF-187) when given with a fixed doxorubicin dose and to determine whether ADR-529 alters doxorubicin pharmacokinetics. METHODS: Twenty-five patients were treated with doxorubicin (60 mg/m2) preceded by administration of ADR-529 in escalating dosages (i.e., 60, 300, 600, 750, and 900 mg/m2) to groups of three to nine patients. ADR-529 was administered over a 15-minute period beginning 30 minutes before doxorubicin treatment; the protocol was repeated every 3 weeks. Blood was sampled frequently for drug levels, which were determined by high-pressure liquid chromatography with fluorescence (doxorubicin) and electrochemical detection (ADR-529). RESULTS: Dose-limiting neutropenia occurred in four of six previously treated patients at an ADR-529 dose of 600 mg/m2; the dose ratio of ADR-529 to doxorubicin was 10:1. For three additional patients with better Eastern Cooperative Oncology Group performance status and a maximum of one prior chemotherapy regimen, 600 mg/m2 was tolerated, but grade 3 or 4 neutropenia occurred in four of six patients who received an ADR-529 dose of 900 mg/m2 and in three of four patients at a dose of 750 mg/m2. Doxorubicin's estimated terminal half-life was 39.5 +/- 18.3 (mean +/- SD) hours; the area under the curve for plasma concentration of drug x time (AUC) was 1.74 +/- 0.40 (micrograms/microL) x hour. Total-body clearance was 598 +/- 142 microL/m2 per minute (N = 20), and it did not vary with ADR-529 dose. Estimated distribution and elimination phase half-lives for plasma ADR-529 were 0.46 +/- 0.30 hours and 4.16 +/- 2.94 hours, respectively. Total-body clearance was 111 +/- 87 microL/m2 per minute (N = 18); AUC was linear (r2 = .92), and the clearance rate was constant (r2 = .18) from 60 to 900 mg/m2. CONCLUSIONS: Myelotoxicity was dose limiting for ADR-529 at 600-750 mg/m2 when given with a fixed dose of doxorubicin at 60 mg/m2 (dose ratios of ADR-529 to doxorubicin ranged from 10:1 to 12.5:1). When used in combination, ADR-529 did not perturb doxorubicin's distribution, metabolism, or excretion; therefore, other mechanisms of cardioprotection must be involved. IMPLICATIONS: We recommend that an ADR-529 dose of 600 mg/m2 be given with single-agent doxorubicin at a dose of 60 mg/m2 in future studies.

Lack of effect of cyclophosphamide on the immunogenicity of a melanoma antigen vaccine.

Melanoma antigen vaccines are a conceptually attractive approach to prevent or delay disease recurrence in patients with surgically resected malignant melanoma. However, the immunogenicity of current vaccines is relatively low. Cyclophosphamide, when given in low doses prior to antigen exposure, is an immunomodulator which has been shown to enhance both humoral and cellular antitumor responses in animals and humans. We conducted a prospective, randomized, clinical trial to study whether pretreatment with cyclophosphamide augments the immunogenicity of a polyvalent, allogeneic, melanoma antigen vaccine in patients with melanoma and low tumor burden. Forty-five patients with resected stage II melanoma (regional metastases) were randomly allocated to treatment with melanoma vaccine or melanoma vaccine plus cyclophosphamide. All patients received the same dose and schedule of vaccine immunizations; those randomized to cyclophosphamide received 300 mg/m2 i.v. 3 days prior to each vaccine immunization. Cellular immune responses were evaluated by delayed-type hypersensitivity (DTH) skin reactivity to a test dose of vaccine at baseline (prior to treatment) and following the fourth immunization. Humoral immune responses were measured by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiographic analysis of indirect immunoprecipitates of patients' sera at the same time points. Twenty-four patients were randomized to cyclophosphamide pretreatment and 21 to vaccine alone; 22 and 18 patients were evaluable in each group, respectively. Differences were statistically nonsignificant with respect to either cellular (DTH) or humoral (antibody) responses between the two groups. DTH responses were induced in 16 of 22 (73%) and 15 of 18 (83%) patients treated with cyclophosphamide plus vaccine and vaccine alone, respectively. The mean posttreatment augmentation in DTH response in the cyclophosphamide group was 9.5 mm, compared with 9.9 mm in the vaccine-only group. Eight of 12 (66%) cyclophosphamide-pretreated patients and 9 of 12 (75%) vaccine-only patients produced increased titers of antimelanoma antibodies following treatment. No differences were observed between the groups in disease-free or overall survival. In summary, low-dose cyclophosphamide pretreatment failed to augment the immunogenicity of a polyvalent, allogeneic, melanoma vaccine in patients with completely resected early-stage melanoma.

Phase II trial of paclitaxel and cisplatin in women with advanced breast cancer: an active regimen with limiting neurotoxicity.

PURPOSE: A phase II study of paclitaxel and cisplatin in patients with advanced breast cancer was performed to determine the objective response rate and make further observations about the toxicity of this regimen. PATIENTS AND METHODS: Patients were required to have histologically proven adenocarcinoma of the breast with no more than one chemotherapeutic treatment for advanced disease. Treatment consisted of paclitaxel 200 mg/m2 administered as a 24-hour intravenous (i.v.) infusion followed by cisplatin 75 mg/m2 i.v. Patients received granulocyte colony-stimulating factor (G-CSF) 5 micrograms/kg subcutaneously on day 3 until WBC recovery. Cycles were repeated every 21 days. Patients continued to receive therapy until disease progression or unacceptable toxicity. RESULTS: Forty-four patients entered the trial. Forty-two patients were assessable for response. Nineteen patients (43%) had no prior chemotherapy and 41 had no chemotherapy for metastatic disease. The median number of cycles administered per patient was five (range, one to seven). There were five complete responses (CRs) (11.9%) and 17 partial responses (PRs) (40.5%), with an overall response rate of 52.4% (95% confidence interval [CI], 36.4% to 68.0%). Nine patients had stage III disease. The response rate for this group was 66.7% (95% CI, 33.0% to 92.5%), with three CRs and three PRs. Among 35 patients with stage IV disease, there were two CRs and 14 PRs, with an overall response rate of 48.5% (95% CI, 30.8% to 66.5%). Overall, the median response duration was 10.6 months. Thirty patients (68%) developed transient grade 4 neutropenia. Cumulative neuropathy was the major dose-limiting toxicity. After five cycles of chemotherapy, 96% of patients had at least grade 1 neurotoxicity and 52% had at least grade 2 neurotoxicity. One patient had a toxic death after cycle 1 of therapy. CONCLUSION: The combination of paclitaxel and cisplatin as first-line chemotherapy for women with advanced breast cancer is an active regimen. However, the cumulative neurotoxicity was significant and dose-limiting in the majority of patients.

Phase I trial of low-dose continuous topotecan infusion in patients with cancer: an active and well-tolerated regimen.

PURPOSE: The objective of this trial was to define the maximum-tolerated dose (MTD) of topotecan for a 21-day infusion schedule, repeated every 28 days, in patients with cancer. PATIENTS AND METHODS: Cohorts of four patients received continuous ambulatory infusions of topotecan in escalated duration with doses beginning at 0.20 mg/m2/d for 7 days. Forty-four patients with a histologic diagnosis of cancer refractory to standard therapy were treated with infusions of topotecan for a total of 115 cycles and 1,780 patient-days of infusion. The median number of treatment cycles per patient was two (range, one to eight). All patients were heavily pretreated with chemotherapy and/or radiation. RESULTS: The dose-limiting toxicity (DLT) was myelo-suppression, with thrombocytopenia greater than neutropenia seen at the dose level of 0.70 mg/m2/d for 21 days. At the MTD of 0.53 mg/m2, ten patients were treated for a total of 20 courses, resulting in one episode of grade 4 thrombocytopenia and leukopenia, one grade 3 thrombocytopenia, and two grade 3 leukopenias. This dose regimen was well tolerated, with minimal nonhematologic toxicity. Local infusion port complications developed in two patients and two had bacteremia, including one patient with repeated local skin infections. Objective responses were observed in this heavily pretreated population for patients with ovarian cancer (two partial responses and one mixed response in six patients), breast cancer (one partial response and one mixed response in two patients), and for one patient each with renal and non-small-cell lung cancer (two partial remissions). CONCLUSION: Twenty-one-day topotecan infusion is well tolerated at 0.53 mg/m2, with dose-intensity exceeding other schedules for administration of topotecan. The DLT is hematologic, with thrombocytopenia somewhat exceeding leukopenia. Objective responses were observed in seven patients with breast, ovarian, renal, and non-small-cell lung cancer.

Double-blind trial of a polyvalent, shed-antigen, melanoma vaccine.

A polyvalent melanoma vaccine prepared from shed antigens stimulates humoral and cellular immune responses and improves survival compared with historical controls. We conducted a double-blind, prospectively randomized, placebo-controlled trial to assess whether this vaccine could slow the progression of resected melanoma. Thirty-eight patients with resected melanoma metastatic to regional nodes (American Joint Committee on Cancer stage III) who had a particularly poor prognosis on the basis of the nodes being clinically positive or two or more histologically positive nodes were randomly assigned in a 2:1 ratio to treatment with 40 microg of melanoma or placebo (human albumin) vaccine, both of which were bound to alum as an adjuvant. Immunizations were given intradermally into the extremities every 3 weeks x 4, monthly x 3, every 3 months x 2, and then every 6 months for 5 years or until disease progression. Twenty-four patients were treated with the melanoma, and 14 patients were treated with the placebo vaccine. The groups were evenly balanced with respect to prognostic factors. Median length of observation was 2.5 years. There was no local or systemic toxicity. By Kaplan-Meier analysis, median time to disease progression was two and a half times longer in patients treated with melanoma vaccine compared with that in patients treated with placebo vaccine, i.e., 1.6 years (95% confidence interval, 1.0-3.0 years) compared with 0.6 year [95% confidence interval, 0.3-1.9 year(s)]. By Cox proportional hazards analysis, this difference was significant at P = 0.03. Overall survival was 40% longer in the melanoma vaccine-treated group (median overall survival of 3.8 years versus 2.7 years), but this difference was not statistically significant. In a double-blind and placebo-controlled trial, these results suggest that immunization with a melanoma vaccine may be able to slow the progression of melanoma. Although statistically significant, these results must be interpreted with caution because they are based on a small number of patients.

Development of tumor-infiltrating lymphocytes in breast cancer after neoadjuvant paclitaxel chemotherapy.

PURPOSE: Neoadjuvant chemotherapy for breast cancer creates new possibilities for the analysis of biological factors in the tumor and/or host, which may play a role in the response to treatment. In this study we analyzed whether changes in local antitumor immunity take place after neoadjuvant paclitaxel therapy and if they correlate with response to treatment. EXPERIMENTAL DESIGN: Neoadjuvant chemotherapy (paclitaxel, 200 mg/m2 q2w, 4 treatments) was followed by definitive surgical management. Histological sections from the pre- and post-treatment surgical specimens of 25 patients were analyzed for the extent of lymphocytic infiltration and presence of tumor infiltrating lymphocytes (TILs). The cumulative apoptotic response in the tumor after the first dose of paclitaxel was also studied in 10 of 25 patients. RESULTS: Pretreatment lymphocytic infiltrate in the tumor was minimal in the majority of patients and showed no relationship with clinical response. In the patients without TILs before treatment, development of TILs after treatment was noted in 0/3 (0%) patients with stable disease, 3/12 (25%) patients with clinical partial response, and 4/6 (67%) patients with clinical complete response and pathological residual disease. These correlated with the tumor cell apoptotic response to the first dose of paclitaxel. CONCLUSIONS: These results suggest that development of TILs after treatment correlates with clinical response to neoadjuvant paclitaxel therapy. The possible mechanism(s) whereby neoadjuvant chemotherapy may lead to induction of antitumor T cells is discussed. Immunological processes may influence the response of breast cancer patients to neoadjuvant treatment.

Effect of prolonged topotecan infusion on topoisomerase 1 levels: a phase I and pharmacodynamic study.

Topoisomerase 1 (topo-1) inhibitors act on the target enzyme by forming "cleavable complex," a high molecular weight DNA protein adduct. The formation of such cleavable complexes results in depletion of the Mr 100,000 "free" topo-1 band detectable by Western blot. The objectives of this study were to determine the maximally tolerated dose of prolonged topotecan infusion in previously untreated and minimally pretreated patients. A secondary objective was to measure the effect of prolonged topotecan infusion on topo-1 levels in peripheral blood mononuclear cells (PBMCs) as a pharmacodynamic end point. In a prior Phase I study of 21-day topotecan infusion (H. Hochster et al., J. Clin. Oncol., 12: 553-559, 1994), the maximum tolerated dose for patients treated previously was 0.53 mg/m2/day for 21 days every 28 days. In this study, patients with no prior therapy were treated similarly at 0.7 mg/m2/day for 21 days, and doses were escalated in 0.1 mg/m2/day increments. Patients who had one prior chemotherapy regimen or radiation therapy to a portal of

Paclitaxel-induced apoptosis and mitotic arrest assessed by serial fine-needle aspiration: implications for early prediction of breast cancer response to neoadjuvant treatment.

The extent of tumor reduction from neoadjuvant chemotherapy for breast cancer correlates with outcome. We investigated whether the initial cellular responses to paclitaxel are related to the extent of tumor reduction. Eleven women with breast cancer received paclitaxel (every 2 weeks for 4 cycles) as neoadjuvant treatment. Serial fine-needle aspirations (FNA; 25-gauge, 1 pass) were obtained before treatment and at 24, 48, 72, and 96 h after the first paclitaxel dose. Microscopic counts of apoptotic and mitotic indices were performed. The change in cancer volume from treatment was determined using radiological measurements with allowance for change in the histopathological amount of cancer. Apoptotic and mitotic responses usually subsided within 4 days. The duration of the initial apoptotic response was different for women with different treatment results. Cumulative apoptotic response for the first 4 days inversely correlated with the proportion of residual cancer after neoadjuvant treatment. FNA is a versatile clinical method to obtain breast cancer cells for therapy response studies. Apoptotic response to the first dose of paclitaxel is almost complete within 4 days, implying that more frequent (weekly) paclitaxel dosing might be beneficial. The apoptotic response to the first dose of paclitaxel appeared to predict the amount of cancer reduction from this treatment. This is a promising start toward the development of an early chemopredictive assay for paclitaxel treatment of breast cancer.

Identification of HLA-A*03, A*11 and B*07-restricted melanoma-associated peptides that are immunogenic in vivo by vaccine-induced immune response (VIIR) analysis.

With the discovery of increasing numbers of tumor antigens, there is a need to rapidly determine whether these antigens and the individual peptides they express are able to stimulate immune responses in vivo and thus, can be used to construct cancer vaccines. In this study we used the method of vaccine-induced immune response (VIIR) analysis to identify multiple immunogenic peptide epitopes derived from several melanoma associated antigens and presented by HLA-A*03, A*11 and B*07. Thirty-one patients with melanoma were immunized to a polyvalent vaccine containing multiple antigens, including MAGE-3, Melan A/MART-1, gp100 and tyrosinase. Their peripheral blood was tested for peptide-specific, vaccine-induced CD8+ T cell responses before and after immunization using an enzyme-linked immune spot (ELISPOT) assay with panels of peptides restricted by these three alleles. The peptides were selected for immunogenic potential based on their strong binding affinity in vitro to HLA-A*03, A*11 or B*07. Overall, 60% of the 20 peptides studied were recognized by at least one patient and 50% of the patients showed a vaccine-induced CD8+ T cell response to at least one peptide that matched their HLA specificity. We conclude that VIIR analysis is an effective strategy to directly identify immunogenic peptides that are good candidates for vaccine construction.

Phase I study of doxorubicin, ICRF-187 and granulocyte/macrophage-colony-stimulating factor.

A group of 16 patients with advanced malignancy were entered on a phase I trial of escalating doses of doxorubicin with ICRF-187 for cardioprotection and granulocyte/macrophage-colony-stimulating factor (GMCSF) for bone marrow protection. Patients received intravenous ICRF-187 (dose ratio 20:1 ICRF-187:doxorubicin) 30 min prior to doxorubicin. GMCSF at a dose of 15 micrograms kg-1 day-1 was self-administered subcutaneously on days 3-14 of the cycle. Doxorubicin was administered every 21 days. Substantial hematological and non-hematological toxicity was seen. Fever, malaise, and pulmonary symptoms, thought to be due to GMCSF, were not eliminated by reduction in the GMCSF dose to 10 or 5 micrograms kg-1 day-1. Severe hematological toxicity was seen despite GMCSF administration and it was not possible to escalate the doxorubicin dose above 72 mg/m2 with this combination. Dose escalation of doxorubicin may be more feasible with the use of other growth factors or growth factor combinations.

Decrease in circulating tumor cells as an early marker of therapy effectiveness.

As melanoma cells are present in the circulation of many patients with this cancer, decreases in their number could provide an early indication of therapy effectiveness. To evaluate this possibility, we examined the effect of treatment with a melanoma vaccine on the number of melanoma cells present in the circulation. PCR was used to detect melanoma cells that expressed the melanoma-associated antigens MART-1, MAGE-3, tyrosinase and/or gp100 in 91 patients with melanoma. Melanoma cells that expressed one or more of these markers were present more often in advanced disease, i.e. in 80% of patients with advanced stage IV compared to in less than one-third of patients with less advanced disease. We then measured circulating melanoma cells in a subset of 43 of these patients who were treated with a polyvalent, shed antigen, melanoma vaccine. The vaccine contains multiple melanoma-associated antigens including MART-1, MAGE-3, tyrosinase and gp100. Immunizations were given intradermally q2-3 weeks x4 and then monthly x3. Prior to vaccine treatment, circulating melanoma cells were detected in 14 (32%) patients. Following 4 and 7 months of vaccine treatment, melanoma cells that expressed any of these markers were present in only nine (21%) and three (7%) of patients, respectively. Thus, vaccine therapy was associated with clearance of melanoma cells from the circulation in 78% of initially positive patients. As the number of these cells declined steadily with increasing length of therapy, it is unlikely that this was due to a random change in their number. Rather it suggests that the decline was a result of the therapy. These observations suggest that the presence of melanoma cells in the circulation is related to the extent of the melanoma, and that their disappearance may provide an early marker of the efficacy of therapy. However, the practical utility of assaying circulating tumor cells as a guide to the effectiveness of therapy or of prognosis will need to be confirmed by correlations with clinical outcome.

Phase II clinical trial of recombinant alpha 2b interferon and 13 cis retinoic acid in patients with metastatic melanoma.

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.

Immunotherapy of malignant melanoma.

The growth of melanoma in humans depends not only on the malignant potential of the tumor but also on the patient's immune response to the melanoma. As a result, a variety of strategies have evolved to treat melanoma by stimulating antitumor immune responses to melanoma. This article reviews the different approaches being taken and the results obtained to date.

Humoral mediator of antigenic competition demonstrated in vivo.

To determine if a soluble mediator of antigenic competition could be demonstrated in vivo, various groups of mice received implants of intraperitoneal Millipore diffusion chambers containing normal spleen cells and sheep erythrocytes (SRC). Priming and boosting the chamber hosts so that a vigorous secondary immune response to horse erythrocytes (HoRC) coincided with chamber implantation resulted in the suppression of the anti-SRC response of the chamber-enclosed cells. Similarly, passive immunization of the chamber hosts with SRC-absorbed anti-HoRC hyperimmune serum suppressed the response of the chamber-enclosed cells to SRC. Thus, serum from hyperimmune mice contains a humoral suppressor substance which mediates antigenic competition.

A phase II study of Didemnin B (NSC 325319) in advanced malignant melanoma: an Eastern Cooperative Oncology Group study (PB687).

PURPOSE: Didemnin B is a novel marine natural product cyclic depsipeptide containing unusual amino acid moieties. This agent demonstrates promising preclinical antitumor activity, including activity against B16 melanoma and against melanoma isolates in the human tumor stem cell assay. METHODS: We conducted a phase II study of Didemnin B, given in Cremophor, at a starting dose of 4.2 mg/m2/IV q 28 days. Patients with measurable metastatic or advanced malignant melanoma were eligible. All patients were previously untreated with chemotherapy and had performance status 0 or 1. Doses were escalated to 4.9 and 5.6 mg/m2 in cycles 2 and 3, respectively. RESULTS: Nineteen patients were entered and treated with a median of one cycle per patient. Eight of these patients went off study for toxicity including 7 with anaphylactoid reactions in the first or second cycle. One patient went off study after 3 cycles with severe myopathy, a newly described toxicity. Two were not evaluable for response and five were considered stable, including one patient with a transient PR of soft tissue disease in the first cycle. Another patient had stable disease for twelve cycles before progressing and one went off study electively after 3 cycles, for a total of 7 patients with stable disease. One patient with a measurable partial remission (PR) and went off study after three cycles due to severe myopathy, a then newly-described toxicity. No hematologic toxicity was seen. Nausea and vomiting were controlled with anti-emetics. CONCLUSIONS: This study was indeterminate with respect to the activity of Didemnin B in melanoma. Signs of activity were seen, particularly in soft tissue masses, though a large number of patients could not be evaluated fully for activity due to the occurrence of anaphylactoid reactions. This study does not preclude a clinically important level of activity for Didemnin B.

Effect of DETOX as an adjuvant for melanoma vaccine.

The identification of effective adjuvants is critical for tumor vaccine development. Towards this end, we examined whether the immunogenicity of a melanoma vaccine could be potentiated by DETOX, an adjuvant consisting of monophosphoryl lipid A (MPL) and purified mycobacterial cell-wall skeleton (CWS). Nineteen patients with resected stage III melanoma were immunized with a polyvalent melanoma antigen vaccine (40 micrograms) admixed with DETOX, q3 wks x 4. Seven patients received vaccine + low-dose DETOX (10 micrograms MPL + 100 micrograms CWS) and 12 received vaccine + high-dose DETOX (20 micrograms MPL + 200 micrograms CWS). A non-randomized control group of 35 patients was treated similarly with 40 micrograms vaccine + alum. One week after the fourth vaccine immunization, melanoma antibodies were increased over baseline in 7/7 (100%) patients treated with vaccine + low-dose DETOX, 8/12 (67%) patients treated with vaccine + high-dose DETOX, and in 4/19 (21%) of vaccine + alum patients. For the entire DETOX group, the antibody response rate was 15/19 (79%) compared 4/19 (21%) in the alum group (p < 0.001). In contrast, a strong delayed-type hypersensitivity (DTH) response (> or = 15 mm increase in DTH response over baseline) was induced in 50% of the entire DETOX group versus in 47% of the alum group. Median disease-free (DF) survival for the entire DETOX group was 17.8 months compared with 32.1 months in the alum group (p < 0.05). In conclusion, DETOX markedly potentiated antibody but had little effect on DTH responses to melanoma vaccine immunization. It did not appear to improve disease-free survival in comparison to alum in this non-randomized study.