A randomized phase III trial in patients with advanced adenocarcinoma of the stomach receiving first-line chemotherapy with fluorouracil, leucovorin and oxaliplatin (FLO) versus fluorouracil, leucovorin and cisplatin (FLP)

LBA4016

Background: Cisplatin-based chemotherapy is a standard option in advanced gastric cancer. However, treatment results have been unsatisfactory so far, with a time to progression (TTP) of 3 to 4 months and an overall survival (OS) of 6 to 9 months. In addition, treatment regimens are too intense and toxicity is considerable. The aim of this 2-arm randomized trial was to determine whether FLO prolongs TTP and reduces toxicity as compared to FLP. Methods: Patients (pts) were randomized to receive FLO: F 2600 mg/m2 24 h infusion, L 200 mg/m2, and oxaliplatin 85 mg/m2, every two weeks or FLP: F 2000 mg/m2 24 h infusion, L 200 mg/m2, weekly, and cisplatin 50 mg/m2, every two weeks. The primary end point was TTP. Main secondary endpoints included toxicity, time to treatment failure (TTF), and OS. Based on a planned sample size of 218 pts, the trial was designed to have an 80% power to detect an improvement in median TTP from 3.5 to 5.0 months (1-sided log-rank test; significance level 0.05). Results: 220 pts (FLO/FLP, 112/108) were randomized between Aug 2003 and Jan 2006. Median age was 64 yrs and median ECOG was 1. 162 pts (FLO, 80; FLP, 81) had disease progression and 25 pts (FLO, 18; FLP, 8) are still under treatment. Median TTP was 5.7 months for FLO and 3.8 months for FLP (log-rank p = 0.081, Wilcoxon p = 0.019). Median TTF was 5.3 months for FLO and 3.1 months for FLP (log-rank p = 0.028). Response to FLO (34%) was superior to FLP (27%), with 15% and 30% of pts having disease progression as best response to FLO and FLP, respectively (chi-square for trend p = 0.012). Median treatment duration was 4.3 months with FLO and 3 months with FLP. FLO was associated with significantly less NCI-CTC grade 1–4 leukopenia, nausea, alopecia, fatigue, and renal toxicity and FLP was associated with significantly less peripheral neuropathy (chi-square for trend p < 0.05). Severe adverse events related to treatment were less frequent with FLO (8.9%) as compared to FLP (18.6%; p = 0.046). Conclusions: FLO reduced toxicity and improved efficacy as compared to FLP. This leads us to consider FLO for future studies in combination with targeted drugs to further improve the outcome of pts with gastric cancer.

No significant financial relationships to disclose.

Results from a phase I dose escalation study of PEGylated glutaminase in combination with 6-diazo-5-oxo-L-norleucine (DON) in advanced malignant solid tumors

13017

Background: To cope with the increased demand with concomitant down-regulation of glutamine synthesis, tumor cells in general have an upregulated glutamine uptake. The rationale is based on the premise that the therapeutic effectiveness of the glutamine anti-metabolite 6-diazo-5-oxo-L-norleucine (DON) is enhanced by strong depletion of the available pool of glutamine through PEGylated glutaminase (PEG-PGA). The optimal dose of PEG-PGA was found in step one of this study. Methods: Step two of this Phase I study was designed to determine the safety and tolerability of 120 I.U./m2 PEG-PGA in combination with increasing dose levels of DON both administered i.v. twice weekly. DON was administered four hours after PEG-PGA at levels of 5–185 mg/m2 with cohorts of three patients. Cohorts were expanded in case of possibly drug related AEs≥G3. All patients exhibited solid tumors of various indications refractory to standard treatment. Toxicity was measured according to NCI-CTC criteria. Response was evaluated according to RECIST criteria. Results: 61 patients have been enrolled in step two of this study wherein 58 received at least one treatment and 46 (57% male) were available for preliminary evaluation. Median age was 62.5 years (range 43–79) and 36% had a Karnofksy-index <90%. At 25 mg/m2 of DON three patients exhibited G3 nausea and vomiting which was managed effectively with antiemetic therapy. Possibly drug related AEs ≥ G3 like dyspnoea (n = 1), allergic reaction (n = 1), haematemesis (n = 1), 1 thrombosis (n = 1) and neurological diseases (n = 4) were reported in 19.6% of the patients. Haematological toxicities were neither frequent nor severe. No G4 toxicity in any dose level has been observed. DLT (two AEs ≥ G3 in one cohort) was reached in the 11th escalation step resulting in an adequate MTD which will be used in the following studies. In 38 patients available for tumor response 1 confirmed PR (renal) and at least 12 SDs have been reported. Conclusions: PEG-PGA in combination with DON has shown promising efficacy in heavily pre-treated solid tumors with a favourable toxicity profile. A clinical proof of concept study with statistically sufficient number of patients is ongoing.

[Table: see text]

Saccharomyces cerevisiae as delivery vehicle for a NY-ESO-1 protein vaccine

2578

Background: Vaccine strategies that target or activate dendritic cells in order to elicit potent cellular immunity are currently the subject of intense research. Here we report that genetically engineered yeast expressing the full-length tumor associated antigen NY-ESO-1 are a versatile host for protein production eliciting MHC class I and II T-cell responses. Methods: The pYD1 yeast display vector was chosen for full length NY-Eso-1 protein (pNY-ESO-1) expression. NY-ESO-1 and SSX-2 (as control) protein were affinity purified on. IFN-g ELISPOT assays were performed in triplicates on nitrocellulose-lined 96-well plates. MHC class I cross-presentation of peptide epitopes was demonstrated by blocking T-cell responses against DCs. For this purpose, antigen or peptide pulsed DCs were labeled with different doses (100, 10, 1 μg/ml) of antibodies specific for HLA-A2/peptide complexes (HLA-A2/ NY-Eso-1157–165; 3M4E5) or an irrelevant antibody (specific for HLA-A2/IMP58–66) as control. Results: Highest level of NY-ESO-1 expression was detected on the cell wall of wt EBY100 strain with lower expression levels on PMT deficient strains PMT-2 and PMT-4. After protein feeding of immature DCs, NY-ESO-1 157–165 peptide cross-presentation was detected by 3M4E5 and an antigen-specific CD8+ T cell clone. There was a strong positive correlation between the amount of Aga2p-NY-ESO-1 protein (0–15μg/ml) and peptide presentation. Specific T-cell recognition of NY-Eso-1 157–165/HLA-A2 complexes was validated by blocking experiments with Fab 3M4E5. Pre-incubation of protein fed DCs with the antibody at different concentrations (0–100 μg/ml) resulted in a significant reduction (p< 0.05) of spot numbers. Efficient presentation and T-cell recognition of epitope 157–165 was only adequately detectable when protein produced by EBY100 wt yeast strain was used (p < 0.05). MHC class II presentation was studied in an autologous setting using a T-cell line recognising the NY-ESO-1 157–170 in HLA-DP4 context revealing that NY-ESO-1 protein produced in yeast was efficiently taken up and presented. Conclusions: Together, these data add further evidence that yeast expressing recombinant proteins can be used for vaccine purposes and that antigen uptake in APC depends on glycoslation of yeast expressed antigens.

No significant financial relationships to disclose.

A phase I repeated dose escalation study of the Polo-like kinase 1 inhibitor BI 2536 in patients with advanced solid tumours

2038

Background: BI 2536 is a novel highly potent and selective inhibitor of the serine-threonine kinase polo-like kinase 1 (Plk1), which is a key regulator of cell cycle progression. Objectives of this trial were the assessment of the maximum tolerated dose (MTD), overall safety, pharmacokinetics and efficacy of BI 2536 given intravenously. Methods: Sequential cohorts of 3 to 6 patients (pts) with pretreated advanced or metastatic solid tumours received intravenous infusions of BI 2536 on days 1 and 8 of a 3-week treatment course following a toxicity guided dose escalation design. Further treatment courses were administered to pts in the absence of disease progression and if toxicity after a 3-week treatment course had resolved. Results: A total of 42 pts was treated at doses of 25 mg (n=3), 50 mg (n=3), 100 mg (n=22), 125 mg (n=5), 150 mg (n=6) and 200 mg (n=3). Reversible CTCAE grade ≥ 3 neutropenia in 14/42 pts represented the main drug related toxicity with an incidence of 3/5 in the 125 mg cohort, 4/6 in the 150 mg and 2/2 in the 200 mg dose cohorts. Dose limiting toxicity (DLT) was defined as drug related toxicity prohibiting administration of the day 8 dose of BI 2536 (hematologic: CTCAE ≥ 3 grade, non-hematologic toxicity: CTCAE ≥ 2). No DLT other than d8 neutropenia was observed. The MTD was defined at 100 mg for the given day 1 and 8 schedule. Further related adverse events (AE’s) were of mild to moderate intensity (CTCAE grade ≤ 2). There were no related AEs resulting in study discontinuation. Preliminary PK analysis showed dose proportionality of Cmax and AUC0-∞ with a high clearance (∼ 1500 mL/min) and a high volume of distribution (∼ 2000 L). No accumulation from d1 to d8 occurred. Patients were treated for up to 8 courses without evidence of accumulating toxicity. No objective responses were observed according to RECIST criteria in this heavily pretreated patient population. Conclusions: In summary BI 2536 is a Plk1 inhibitor with a favorable PK and safety profile at the tested dose and schedule. Neutropenia as a mechanism-related toxicity indicates target inhibition in vivo.

[Table: see text]

Dose escalation study for defining the maximum tolerated dose of continuous oral trofosfamide in pretreated patients with metastatic lung cancer

BACKGROUND

Trofosfamide is increasingly used in the treatment of patients with several types of malignancies. However, the optimal dose of trofosfamide for patients with advanced cancer has not been systematically investigated yet. The aim of this study was to define the maximum tolerated dose (MTD) of continuous oral trofosfamide.

PATIENTS AND METHODS

16 patients with advanced lung cancer (14 nonsmall cell lung cancer, 2 small cell lung cancer; 10 male, 6 female; median age 64 years (range 46-82); median Karnofsky status 70%; median number of organs involved 3 (range 1-6)) were enrolled. All patients were previously treated with chemotherapy (median 2x, range 1-6) and 8/16 (50%) with radiotherapy. Patients received trofosfamide p.o. administered in 3 doses per day for 3 weeks (1 cycle) using a 3-patient-cohort dose-escalation strategy. Toxicities were graded according to the WHO Criteria.

RESULTS

Patients received a median of 2 cycles of trofosfamide (range 1-4) at 3 dose levels (90, 125, and 175 mg/m2). Grade 3 and 4 neutropenia, anemia, and thrombocytopenia were observed in 20, 13.3, and 6.6%, respectively. Dose-limiting toxicities during the first cycle were grade 3 muscle weakness and anorexia observed in 1/6 patients in cohort 1 (trofosfamide 90 mg/m2), grade 3 neutropenia in 1/6, and encephalopathy in 1/6 patients in cohort 3 (trofosfamide 175 mg/m2). Therefore, the dose level of 125 mg/m2 was defined as the MTD.

CONCLUSION

Trofosfamide at 125 mg/m2 administered in 3 doses per day was well tolerated. This dose level is recommended for further clinical studies.

Synchronous bilateral endoscopic adrenalectomy: experiences after 18 operations

BACKGROUND

Patients who undergo unilateral adrenalectomy are known to benefit from the endoscopic procedure. Only a few reports on bilateral endoscopic adrenalectomy exist. The optimal approach and the value of this operation were assessed in this study.

METHODS

For 18 patients, synchronous bilateral lateral adrenalectomy with intraoperative repositioning was performed for different indications. The transperitoneal and retroperitoneal approaches were varied on both sides.

RESULTS

With the reported procedure, the operative time diminished considerably. Blood loss was low, and no blood transfusions were required. No conversion to an open procedure was necessary. There were no intraoperative or postoperative complications, except for one death from pulmonary embolism. The mean postoperative hospital stay was 7 days, and the follow-up evaluation showed overall improvement.

CONCLUSION

The risk associated with endoscopic bilateral adrenalectomy is low. Transperitoneal and retroperitoneal lateral adrenalectomy are recommended as approaches of choice. The authors advocate early bilateral adrenalectomy for Cushing's disease after unsuccessful transsphenoidal operation and ectopic adrenocorticotropic hormone production from an inaccessible tumour.

Numbers of colony-forming progenitors in patients with systemic mastocytosis: potential diagnostic implications and comparison with myeloproliferative disorders

BACKGROUND

An increase in colony-forming progenitor cells (CFU) is typically seen in myeloproliferative disorders (MPD). Systemic mastocytosis (SM) is a haemopoietic neoplasm involving myeloid progenitors similar to MPD. In the present study, we measured the levels of peripheral blood (pb) and bone marrow (bm) CFU in patients with different categories of SM, and compared them with those obtained in MPD patients and healthy controls.

MATERIALS AND METHODS

Numbers of CFU (CFU-GM, BFU-E, CFU-GEMM) were measured in a colony assay in 25 patients with SM [indolent SM (ISM), n = 15; smouldering SM (SSM), n = 3; SM with an associated haematologic clonal non-mast cell lineage disease (SM-AHNMD), n = 5; aggressive SM (ASM), n = 1; mast cell leukaemia (MCL), n = 1] and 37 with MPD [chronic myeloid leukaemia (CML), n = 10; polycythemia vera (PV), n = 8; essential thrombocytosis (ET), n = 9; idiopathic myelofibrosis (IMF), n = 10].

RESULTS

In the patients with MPD, elevated numbers of pb CFU were detected in all groups when compared with healthy controls (P < 0.05). In most of the patients with ISM, circulating CFU levels (CFU-GM, BFU-E, and CFU-GEMM) were within the normal range. In SSM, pb CFU-GM levels were normal in two patients, and elevated in a third patient. In the "SM-AHNMD-group", CFU levels were found to reflect the nature of the AHNMD: in SM with concomitant acute myeloid leukaemia (SM-AML, n = 2), the levels of CFU were low or undetectable, whereas in SM with chronic myelomonocytic leukaemia (SM-CMML, n = 2), elevated numbers of pb CFU-GM were found.

CONCLUSION

The numbers of CFU are normal in patients with ISM, but elevated in some patients with SSM and SM-CMML. An elevated CFU level in SM should raise the suspicion of an associated MPD (CMML) or smouldering SM, a novel SM-subtype that shares several features with MPD and sometimes progresses to an overt SM-MPD.

Circulating myeloid colony-forming cells predict survival in myelodysplastic syndromes

The growth characteristics and the prognostic value of cytokine-stimulated myeloid colony formation from peripheral blood mononuclear cells (PBMC) of patients with myelodysplastic syndromes (MDS) are largely unknown. In this study we have determined the number of myeloid colony-forming units (mCFUs) in semisolid medium from 112 MDS patients and correlated them with French-American-British (FAB) type, the international prognostic scoring system (IPSS), karyotype, peripheral blood (PB) and bone marrow (BM) blast cells, cytopenias, lactate dehydrogenase (LDH), and survival data. Concerning the FAB classification, lower median mCFUs were found in patients with refractory anemia (RA) and refractory anemia with ringed sideroblasts (RARS) compared to refractory anemia with excess of blast cells (RAEB) and refractory anemia with excess of blasts cells in transformation (RAEB-T). In vitro growth in MDS clearly correlated with the cytogenetic risk groups defined by the IPSS (30.5/10(5) PBMCs with favorable karyotypes, 191 in the intermediate prognostic group, 677 with unfavorable cytogenetics, p=0.015 favorable vs unfavorable). BM blast cells >5% (60.5 vs 255 colonies, p=0.032) as well as LDH levels above the normal limit (64.5 vs 425 colonies, p=0.045) were also associated with higher colony formation. Patients were stratified according to the number of circulating mCFUs into a low growth, intermediate growth and high growth group. Median survival was 343 days in the high growth, 1119 days in the low growth, and 2341 days in the intermediate growth group ( p=0.0002). Multivariate analyses revealed colony growth ( p=0.0056), PB blast cells ( p=0.0069), cytogenetic risk group ( p=0.024), and platelet count ( p=0.018) to predict survival in our patients. After inclusion of the IPSS risk categories, mCFU levels remained a highly predictive parameter for survival ( p=0.0056) and acute myeloblastic leukemia (AML) transformation ( p=0.0003).

Reduced-dose cladribine (2-CdA) plus mitoxantrone is effective in the treatment of mantle-cell and low-grade non-Hodgkin's lymphoma

Cladribine (2-chlorodeoxyadenosine) (2-CdA) has been shown to be effective in mantle-cell (MCL) and low-grade lymphomas (lgNHL). The aim of this multicentre study was to evaluate the rate and duration of remissions and to examine the toxicity of the combination of reduced-dose 2-CdA and mitoxantrone (CdM) in MCL and lgNHL as first-line therapy or for patients in their relapse. A total of 285 courses, median of five courses per patient, were administered to 62 evaluable patients (42 previously untreated, 20 relapsed) with 5 mg/m(2) 2-CdA per day given as an intermittent 2-h infusion over 3 consecutive days combined with 8 mg/m(2) mitoxantrone on days 1 and 2 for the untreated patients or 12 mg/m(2) mitoxantrone on day 1 for patients in their first relapse for a maximum of six cycles every four weeks. 32 follicular, 18 MCL, 9 lymphoplasmacytoid, 2 marginal zone and 1 unclassified low-grade B-cell lymphoma were involved in the study. 56 of the 62 patients responded to CdM resulting in an overall response rate of 90% (95% confidence interval (CI), 80-96%) with a complete remission (CR) rate of 44% (95% CI, 31-57%) and a median duration of remission of 25 months (range 6-42+). The overall survival rate at 48 months was 80%. For 42 previously untreated patients, the overall response rate was 88% (95% CI, 74-96%) with a CR rate of 38% (95% CI, 24-54%), whereas the response rate for the group of 20 previously treated patients was similar with a 95% overall response (95% CI, 75-100%) and a CR rate of 55% (95% CI, 32-77%). In MCL, CdM showed a high activity, achieving a response rate of 100% (95% CI, 81-100%) with a CR rate of 44% and a median duration of remission of 24 months (range 6-35+). Myelosuppression was the major toxicity with 23% grade 3 granulocytopenia and 50% grade 4. Thrombocytopenia was less commonly observed, with only 8% grades 3 and 4. These results demonstrate that the combination of reduced-dose 2-CdA and mitoxantrone is a highly active regimen in the treatment of low-grade lymphomas, and in particular of MCL.

Chemical investigation of hassium (element 108)

The periodic table provides a classification of the chemical properties of the elements. But for the heaviest elements, the transactinides, this role of the periodic table reaches its limits because increasingly strong relativistic effects on the valence electron shells can induce deviations from known trends in chemical properties. In the case of the first two transactinides, elements 104 and 105, relativistic effects do indeed influence their chemical properties, whereas elements 106 and 107 both behave as expected from their position within the periodic table. Here we report the chemical separation and characterization of only seven detected atoms of element 108 (hassium, Hs), which were generated as isotopes (269)Hs (refs 8, 9) and (270)Hs (ref. 10) in the fusion reaction between (26)Mg and (248)Cm. The hassium atoms are immediately oxidized to a highly volatile oxide, presumably HsO(4), for which we determine an enthalpy of adsorption on our detector surface that is comparable to the adsorption enthalpy determined under identical conditions for the osmium oxide OsO(4). These results provide evidence that the chemical properties of hassium and its lighter homologue osmium are similar, thus confirming that hassium exhibits properties as expected from its position in group 8 of the periodic table.

Quantitative assessment of the expression of melanoma-associated antigens by non-competitive reverse transcription polymerase chain reaction

The assessment of tumor-associated antigens (TAA) recognized by T lymphocytes is a prerequisite for diagnosis and immunotherapy of melanoma. Different reverse transcription-polymerase chain reaction (RT-PCR) protocols allowing the quantification of the TAA mRNA expression in the solid tumor or the detection of circulating melanoma cells have been described. We have recently shown a positive correlation between the amount of specific product formed by RT-PCR and the staining intensity in immunohistochemical analysis of the corresponding sample. Here we describe a quantification procedure based on the direct digitization of the PCR products after separation on ethidium bromide-stained agarose gels, followed by computer-assisted densitometry. To standardize our method, we examined the linear range of the densitometric quantification procedure as reflected by the correlation of signal intensity to the amount of the corresponding DNA. As an internal measure for the so-termed cDNA in the different samples after RNA isolation and reverse transcription, a beta-actin PCR was introduced. Subsequently, we chose four sets of primers for the melanoma-associated antigens MAGE1, tyrosinase, Melan A/MART-1 and gp100/Pmel17 and performed PCR analysis over a range of cycle numbers. In each case, the amplification rate remained constant up to at least 26 cycles under the respective conditions. Plotting the logarithm of the amount of product against the cycle number yields a slope that equals the logarithm of the amplification rate. The amount of starting material can be determined from the intercept with the ordinate. In summary, the method introduced in the present work allows the quantification of TAA in melanoma which might be important for the monitoring of disease. Technically the method is sound and sensitive, avoids post-PCR manipulations and can be performed with the standard equipment of a molecular biology laboratory. It can be applied also to other solid tumors and leukemias.

Immune responses to tumour antigens: implications for antigen specific immunotherapy of cancer

Tumour associated antigens recognised by cellular or humoral effectors of the immune system are potential targets for antigen specific cancer immunotherapy. Different categories of cancer antigens have been identified that induce cytotoxic T lymphocyte (CTL) responses in vitro and in vivo, namely: (1) "cancer testis" (CT) antigens, expressed in different tumours and normal testis, (2) melanocyte differentiation antigens, (3) point mutations of normal genes, (4) self antigens that are overexpressed in malignant tissues, and (5) viral antigens. Clinical studies with peptides and proteins derived from these antigens have been initiated to study the efficacy of inducing specific CTL responses in vivo. Immunological and clinical parameters for the assessment of antigen specific immune responses have been defined-delayed type hypersensitivity (DTH), CTL, autoimmmune, and tumour regression responses. Specific DTH and CTL responses and tumour regression have been observed after the intradermal administration of tumour associated peptides alone. Peptide specific immune reactions were enhanced after using granulocyte macrophage stimulating factor (GM-CSF) as a systemic adjuvant by increasing the frequency of dermal antigen presenting Langerhans cells. Complete tumour regression has been observed in the context of measurable peptide specific CTL. However, in single cases with disease progression after an initial tumour response, either a loss of single antigens targeted by CTL or of the presenting major histocompatibility complex (MHC) class I allele was detected, pointing towards immunisation induced immune escape. Cytokines to modulate antigen and MHC class I expression in vivo are being evaluated to prevent immunoselection. Recently, a new CT antigen, NY-ESO-1, has been identified on the basis of spontaneous antibody responses to tumour associated antigens. NY-ESO-1 appears to be one of the most immunogenic antigens known to date, with spontaneous immune responses observed in 50% of patients with NY-ESO-1 expressing cancers. Clinical studies have been initiated to evaluate the immunogenicity of different NY-ESO-1 constructs to induce both humoral and cellular immune responses in vivo.

A pilot study of whole body hyperthermia and carboplatin in platinum-resistant ovarian cancer

The aim of this study was to determine whether the addition of whole body hyperthermia (WBH) to carboplatin (CBDCA) can induce responses in patients with platinum-resistant ovarian cancer. 16 pretreated patients with platinum-resistant ovarian cancer were entered on a Systemic Hyperthermia Oncological Working Group (SHOWG) study; (14 patients were eligible with 14 evaluable for toxicity and 12 for response). The patients were treated with WBH (Aquatherm) 41.8 degrees C x 60 min in combination with carboplatin (CBDCA) (area under the curve (AUC) of 8) every 4 weeks. Disease status was evaluated every two cycles. Patients were treated for a maximum of six cycles. One patient had a complete response (CR) and 4 had a partial response (PR). 4 patients had stable disease (SD). 3 patients had progressive disease (PD). 2 patients were unevaluable: 1 had a bowel obstruction shortly after her first treatment; the second patient achieved a CR, but only had one treatment secondary to an idiosyncratic reaction to sedative drugs. 2 patients entered on study were ineligible, as they did not meet criteria for platinum resistance; 1 entered a CR and 1 had SD. Dose-limiting toxicity, which required CBDCA dose reductions, was grade 4 thrombocytopenia. Other toxicities included neutropenia (grade 3/4), and nausea and/or vomiting. Consistent with preclinical modelling, these results suggests that 41.8 degrees C WBH can overcome platinum resistance in ovarian cancer. These observations suggest further investigation of the therapeutic potential of WBH in a group of patients who historically fail to respond to salvage therapies is warranted.

Analysis of HLA class I expression in different metastases from two melanoma patients undergoing peptide immunotherapy

We characterized the HLA class I alterations in five metastases obtained from two patients with melanoma immunized with Melan A/MART-1, tyrosinase and gp100 tumor peptides. All three metastases analyzed in the first patient (NW145) showed a similar HLA class I alteration with a dual population of melanoma cells. One population was HLA class I antigen positive and the other had loss of heterozygosity (LOH) in the short arm of chromosome 6 leading to an HLA haplotype loss (A02011, B4007, Cw1). The absence of HLA-A2 antigen may explain why this patient did not develop HLA-A2 restricted, Melan A/MART-1 specificity immunization, since this HLA molecule is the restriction element for the tumor peptides used. However, this HLA-deficient population was not selected after peptide immunotherapy. The primary tumor in this patient presented LOH in region 6q, but only in the vertical growth phase of the lesion, whereas LOH at 6p was observed only in DNA from metastatic material. The second patient (NW16) also presented two metastatic lesions with an identical HLA molecular defect, i.e. HLA B locus downregulation (HLA B51011: serological B51; B1503: serological B70). One lesion expressed the tumor antigen (Melan A/ MART-1), but the other did not. Interestingly, the antigen-positive metastasis regressed after peptide immunotherapy, whereas the other progressed rapidly. These findings provide the first indication that multiple metastases generated in the same host can have identically altered HLA class I phenotypes.

Vaccination for malignant melanoma: recent developments

The identification of tumor-associated antigens recognized by cellular or humoral effectors of the immune system has opened new perspectives for cancer immunotherapy. Different categories of cancer-associated antigens have been described as targets for CD8+ T cells in vitro and in vivo: (1) 'cancer-testis' (CT) antigens expressed in different tumors and normal testis; (2) melanocyte differentiation antigens; (3) point mutations of normal genes; (4) antigens that are overexpressed in malignant tissues, and (5) viral antigens. Clinical trials with antigenic peptides have been initiated to induce specific immunological responses in vivo. Immunological and clinical parameters for the assessment of peptide-specific reactions have been defined: DTH, CD8+ T cell, autoimmune and tumor regression responses. Preliminary results show that tumor-associated peptides alone elicit specific DTH and CD8+ T cell responses associated with tumor regression after intradermal vaccination. Granulocyte macrophage colony-stimulating factor has been shown to enhance peptide-specific immune reactions by amplification of dermal antigen-presenting dendritic cells. Complete tumor regressions have been observed after the induction of CD8+ T cell responses by peptide immunization. Based on these results, active immunotherapy with tumor-associated antigens may be a promising approach for patients in adjuvant treatment situations, who are at high risk for tumor recurrence. Recently, a strategy utilizing spontaneous antibody responses to tumor-associated antigens (SEREX) has led to the identification of a new CT antigen, NY-ESO-1. NY-ESO-1-specific spontaneous humoral and cellular immune responses were found in approximately 50% of patients with NY-ESO-1-positive tumors. Clinical studies have been initiated to evaluate the immunological effects of immunization with NY-ESO-1 peptides in cancer patients with detectable or absent immunity against NY-ESO-1.