Archive for the Melanoma category.
Posted on April 3rd, 2008 by Canadian Health in
Melanoma
A randomized adjuvant trial of GM2/BCG given following surgery for stage III melanoma (AJCC staging) has been conducted in 122 patients at Memorial-Sloan-Kettering Cancer Center (MSKCC) between 1987 and 1988. This trial, reported at more than 5 years of follow-up, has demonstrated the induction of IgM anti-GM2 antibodies in a majority of patients who were immunized, and the presence of native antibodies against GM2 in a small (fewer than 5%) subset of unvaccinated patients in the control group. Antibody response against GM2 was again demonstrated to be a highly significant and favorable prognostic factor. In addition, vaccination was associated with a prolongation of relapse-free survival of borderline statistical significance, confounded by the occurrence of native anti-GM2 antibody responses among six patients in the total, five of whom were entered into the control group. Analysis of the efficacy of immunization among seronegative entrants into this protocol revealed a significant improvement of relapse-free survival associated with GM2/BCG vaccination ( P = .02).
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To further augment the immunogenicity of GM2, a variety of measures have been explored. Covalent attachment of GM2 to carrier proteins, such as keyhole limpet hemocyanin (KLH), has improved the titer and durability of the IgM response seen with BCG and GM2 and induced antibody of the IgG isotype for the first time. A phase-III evaluation of the GM2-KLH vaccine with the QS21 adjuvant has been planned in the ECOG and US Intergroup mechanism, as well as in England.
Posted on April 2nd, 2008 by Canadian Health in
Melanoma
Several centers have investigated the immunogenicity of lysates derived from tumor cells infected with Newcastle disease virus, vaccinia virus, and vesicular stomatitis virus. A multicenter randomized controlled prospective clinical trial that enrolled 250 patients with resected moderate- to high-risk melanoma was recently reported demonstrating the lack of any therapeutic benefit of immunization with the Newcastle disease virus viral oncolysate approach. This is the only randomized controlled multicenter trial of a melanoma tumor cell vaccine reported in the literature. Our understanding of molecular biology of immune response to melanoma has increased greatly since the design of this trial. We know the importance of tumor cell expression of histocompatibility antigens (e.g., HLA-A2) that were lacking in this tumor vaccine, or costimulatory molecules (B7.1) that may have been suboptimal in the vaccine. Yet this trial demonstrates the approach that will be necessary to evaluate the most promising vaccine candidates in the adjuvant setting. As with the SWOG 9035 trial (see later), the eligibility criteria for this trial included T3 (AJCC IIA) lesions for which prognosis is more heterogeneous than for stage IIb or a stage III disease, and the sample size was insufficient to detect small benefits.
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The allogeneic tumor cell vaccine reported first by Mitchell and colleagues, admixed with the immunologic adjuvant Detox (Ribi Immunochem Res, Hamilton, MT) has been studied in a second large multicenter randomized trial that is enrolling moderate-risk T3 N0 patients, and will be completed in 2006. This study has been enlarged from its original goal to 600 patients to increase the power of the trial, and its ability to detect more subtle movements in relapse-free survival. In addition, the understanding of the nature of melanoma antigens recognized has moved forward rapidly, including the discovery of a number of peptide antigens whose recognition is restricted by the HLA-A2 allele, which was absent in the tumor cell lines employed in this vaccine trial.
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Another approach to increasing immune response has been to alter tumor cells by binding haptens to autologous tumor cells. Pilot single-institution data with haptenated autologous tumor cells have been intriguing but, to date, this type of vaccine has not been evaluated in a randomized controlled or multicenter trial, owing in part to the difficulty of manipulating autologous tumor cells for the vaccine.
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A variety of efforts are also underway to immunize melanoma patients with purified or partially purified preparations of potentially immunogenic molecules from melanoma cells. The rationale for this approach comes from the identification of antigens on melanoma cells that can be recognized by antibodies in sera or lymphocytes from patients with melanoma. A large experience using partially purified cultured allogeneic tumor cell antigens has been the stimulus for the initiation of controlled trials of one vaccine preparation derived from shed antigens of cultured melanoma cell lines. Gangliosides have been shown to induce antibody responses after immunization. Of particular interest is that the ganglioside GM2 induces IgM antibody responses in more than 80% of patients immunized with GM2 and BCG following cyclophosphamide treatment at low dose as an immunomodulator. A prospective randomized study evaluated the role of vaccination for 6 months against GM2 with BCG, in comparison to BCG alone, using low-dose cyclophosphamide pretreatment in both groups.
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Serologic studies have shown a favorable prognostic significance for the presence of anti-GM2 ganglioside antibodies, suggesting that the induction of antibodies against gangliosides may confer protection from relapse and mortality due to melanoma. However, native autologous antibody reactivity against GM2 is infrequently detected in patients with melanoma. A variety of vaccination programs utilizing intact autologous and allogeneic cells, and cell fractions derived from allogeneic melanoma cell lines, have been employed to increase immune responses to autologous melanoma cells. The most promising results from randomized controlled trials of vaccination have emerged from studies of purified ganglioside GM2. Livingston and colleagues have performed a series of trials employing autologous tumor cells, and more recently purified ganglioside preparations, with various immunologic adjuvants. The combination of BCG given together with ganglioside GM2 has been shown to induce the formation of increased titers of IgM antibodies in the majority of patients immunized (33 of 44).
Posted on April 2nd, 2008 by Canadian Health in
Melanoma
Tumor vaccines have a long history, but the search for effective methods to induce active immunity against tumors has been difficult. Repeated attempts have been made to inhibit the outgrowth of tumors and influence the natural history of melanoma by immunization against tumor cells or extracts of tumor cells. More recently, purified antigens recognized by the host antibody response, as well as the epitopes defined by T-cell responses, have been identified and prepared for use as vaccines. In addition, genetically modified melanoma cells, recombinant vaccines, and antiidiotype antibodies that represent the antibody-recognized antigens of melanoma have entered into clinical trials. Evidence is mounting that vaccination can induce immune responses to melanoma. Efforts to vaccinate patients against the antigens of melanoma can be classified categorically into trials of allogeneic tumor cell immunization, autologous tumor cell immunization, and immunization against synthetic chemically defined antigens.
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The last category can be subclassified into approaches directed at the induction of antibody responses, such as the gangliosides noted below, and approaches directed at the induction of a T-cell response to antigens that may include either proteins or peptides. Formal phase III trials have been initiated to evaluate the potential efficacy of relatively few tumor vaccines as adjuvant therapy in high-risk patients.
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At this point, it remains unclear which approaches will be most effective. The multitude of different ongoing trials listed indicate that there is no consensus on vaccine strategies. Early clinical trials of each of the categories of vaccines have been conducted in patients with metastatic disease, for reasons of safety evaluation. Despite early concerns, no reports of tumor enhancement have been documented with the whole-cell vaccination trials conducted to date. Antitumor responses have been recorded in a small fraction of subjects with metastatic disease, receiving varied programs of tumor cell immunization against allogeneic tumor cells incorporating two of three cell lines of hapten-coupled autologous [autochthonous] tumor cells. Most subsequent clinical studies have been performed in patients after resection of regional lymph node metastases or high-risk primary lesions. A more interesting observation is that patients who develop evidence of immune responses have improved disease-free survival or overall survival. This intriguing correlation does not directly imply that vaccines improve the clinical course (for instance, patients who a priori have a better prognosis may be more likely to develop an immune response to vaccination), but is consistent with the hypothesis that an immune response induced by vaccination may have antitumor benefit. A number of problems exist in the construction of tumor vaccines, including the weak immunogenicity of tumor antigens, heterogeneity of tumor-restricted antigen expression in tumors, and the ability of tumors to escape any immune responses that may be induced naturally, or therapeutically. Most melanoma antigens on tumor cells are not tumor-restricted or specific (i.e., present only on cancer cells) but are shared with certain normal cells.
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Active specific vaccination trials in melanoma (as opposed to nonspecific vaccination with BCG) have progressed from the use of unmodified, irradiated allogeneic or autologous melanoma cells for immunization, either alone or in combination with BCG and other nonspecific immunomodulators. It has been difficult to demonstrate any benefit or specific immune responses in the course of these trials. One exception has been immune responses to gangliosides, the major acidic glycolipid of melanoma cells, in some patients immunized with selected allogeneic melanoma cells.
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Efforts have been made to improve immunogenicity of allogeneic tumor cells by treating with the enzyme neuraminidase to remove sialic acid residues from the cell surface. Strategies have been developed to augment the immune response to tumor antigens by infecting tumor cells with nonpathogenic viruses. Viral proteins presented on the cell membrane of tumors have been shown to augment the immunogenicity of tumor antigens.
Posted on April 1st, 2008 by Canadian Health in
Melanoma
The WHO Melanoma Program Trial 16 has evaluated the efficacy of a lower, less-toxic dosage of IFN- alpha2a, given 3 MU/d subcutaneously three times weekly for 3 years versus observation. Of 444 patients who entered this trial, a majority exhibited extracapsular extranodal involvement, a pathologic variable that made patients ineligible for the trials of the US Cooperative groups previously noted. The analysis of WHO Trial 16 has been reported preliminarily at 22 months of follow-up, and in a subset analysis an interaction between age and gender and treatment was found. This interim analysis of subsets, defined by the presence or absence of extranodal extension, has suggested an influence of this therapy upon intranodal disease, and lack of any trend to benefit among patients with extracapsular extension. Subsequent reports of interim analyses of this trial at intervals up to 39 months median follow-up have suggested the absence of a significant impact upon either relapse-free or overall survival. Canadian cialis
In summary, the analyses of E1684, NCCTG 83-7052, and WHO 16, taken together, argue that IFN- alpha2b at higher dosages, delivered intravenously, may be necessary for the benefit observed in E1684. Equivalent dosages of IFN- alpha2a administered by the IM route for shorter periods have been less effective, and lower dosages of IFN- alpha2a administered by the subcutaneous route for longer periods have been ineffective to date. The approval of IFN- alpha2b for adjuvant therapy within 2 months of surgery of high-risk node-positive and deep primary melanoma is the first adjuvant therapy approved for melanoma, and the first new agent approved for therapy of this disease in any stage or setting, since dacarbazine.
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The evaluation of newer and potentially more effective biologic agents in the adjuvant setting has been pursued in multiple trials. SWOG 86-42 is a trial of IFN- alpha administered at dosages projected to be the optimal immunomodulatory dosages (0.2 mg/d sc qod for 1 year). IFN- alpha is among the most potent immunomodulators yet tested, and one for which initial hopes for adjuvant and metastatic disease applications were elevated even beyond IFN- alpha2. As previously noted, the therapeutic activity of IFN gamma in the advanced disease setting has been negligible. The recently published SWOG 86-42 trial demonstrates the lack of therapeutic benefit for this agent at the dosage tested, in either intermediate-risk stage II or stage III resected melanoma. Of concern is that the initial report of this trial suggested a potentially adverse impact of treatment that has not yet been confirmed. In any case, the unequivocal failure of IFN- gamma to improve relapse-free or overall survival in the adjuvant setting argues that the effects of the dose, route, and schedule of IFN- gamma and the monocyte activation and NK activation associated with IFN- alpha administered as in this trial are not sufficient to alter the outcome of this disease. The pleiotropic effects of IFN- alpha2b, which account for its therapeutic benefit in melanoma, have yet to be proven. In vivo activities that may be important range from a direct antiproliferative and cytotoxic action to immunopotentiation of T- or B-cell host responses, dendritic cell antigen presentation, anti-angiogenesis factor, and tumor-restricted antigen expression. These are being evaluated prospectively in the context of the recently completed intergroup trial (ECOG 1690/SWOG 91-11, CALGB 91-90).
Posted on April 1st, 2008 by Canadian Health in
Melanoma
In an accompanying editorial on the E1684 ECOG trial, Balch and Buzaid questioned the role of adjuvant IFN- alpha in a high risk for recurrence patient whose tumor is greater than 4.0 mm thick and lymph node examination is clinically negative. Although excluded from the ECOG eligibility criteria for the E1684 trial, these patients have a greater than 60% chance of harboring microscopic nodal metastases and therefore may benefit from adjuvant high-dose interferon therapy. Knowing the pathologic status of the regional nodes in patients with thick melanomas provides important prognostic information. Patients with thick melanomas who have negative nodes have a significantly better prognosis than those with positive nodes (58% to 71% versus 32% to 42%). The available data from the ECOG E1684 trial were derived from patients whose lymph node pathology was known. The benefit of this therapy was seen for patients who entered the trial with lymph node involvement by comparison with the small subgroup of patients with thick, lymph node negative tumors. These authors therefore recommended that patients with melanomas greater than 4.0 mm have a nodal staging procedure, preferably intraoperative lymphatic mapping and sentinel lymph node biopsy, since this is the least morbid approach. Extrapolation of the results of E1684 may be considered for patients with local recurrences, satellite lesions, or in-transit metastases. Important questions that remain to be answered are whether the high-dose intravenous induction is necessary (or may in fact be sufficient to obtain the benefit of the E1684 treatment) and whether more prolonged interferon administration would enhance the benefit. In addition, the question remains whether early IFN- alpha therapy (after microscopic nodal metastases are removed) is better than late adjuvant therapy (after grossly positive nodal disease is resected with a therapeutic node dissection).
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Only a small subset of patients who receive high-dose IFN- alpha2b therapy actually derived benefit from it. Serum markers of tumors may provide a key to the more selective application of adjuvant therapy. Tyrosinase (a key enzyme in melanin biosynthesis whose gene is actively expressed only in melanocytes, melanoma cells, and Schwann cells) may serve as a marker of early dissemination of disease to allow more selective use of adjuvant therapy in the future. Because melanocytes and melanoma cells do not usually circulate in the blood, the detection of tyrosinase mRNA by reverse transcriptase-polymerase chain reaction (RT-PCR) in blood is considered a potential indication of the presence of circulating melanoma cells. Patients who have a positive RT-PCR before starting therapy that subsequently becomes negative may be those who benefit from the therapy. Human Growth Hormone
The North Central Cancer Treatment Group (NCCTG 83-7052) evaluated the adjuvant role of IFN- alpha2a given at 20 MU/IM three times weekly for 3 months, versus observation in patients with 1.69-mm Breslow depth T3+ or T4, and N1 patients (subsets of AJCC stages IIA or IIB and III). An analysis of 260 evaluable patients who entered this trial demonstrates no significant prolongation of survival, or of relapse-free interval overall. Subset evaluation of patients in stage II as opposed to those in stage III participating in this trial reveals a potential impact in the latter, by Cox analysis.
Posted on March 31st, 2008 by Canadian Health in
Melanoma
LACK OF EFFICACY OF ADJUVANT ISOLATED LIMB PERFUSION
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Isolated limb perfusion does not seem to have a role in the adjuvant treatment of patients who have high-risk melanoma of the limbs. In the recently completed EORTC/WHO adjuvant trial, patients with melanomas greater than 1.5 mm thick were randomized to WLE and observation or WLE and prophylactic hyperthermic isolated limb perfusion. A significantly decreased local recurrence rate was noted in the perfused population, but the distant disease-free survival and overall survival were the same. Thus, prophylactic perfusion using melphalan cannot be recommended.
ROLE OF ADJUVANT SYSTEMIC THERAPY FOR PATIENTS WITH MELANOMA AT HIGH RISK FOR RECURRENCE
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Advances in melanoma treatment over the past decade have evolved primarily from more detailed knowledge about prognostic factors of primary and metastatic lesions. Within the larger group of melanoma patients who undergo potentially curative treatment by surgical resection, subgroups can be identified who are at high risk for recurrence and for development of systemic metastases. Patients with melanomas 1.51 to 3.99 mm deep have a variable and intermediate risk of relapse, while patients with thick primary melanomas (more than 4 mm thick), in-transit lesions, and regional lymph node involvement are at particularly high risk: the 5-year relapse risk of these stage groupings generally exceeds 50%. Once distant metastases develop, median survival is only 6 to 9 months. The investigation of adjuvant systemic treatment that can prevent melanoma recurrence has become a critical area of investigation, focused upon either the intermediate or high-risk stage groups. The rationale and general principles for adjuvant treatment of cancer are based on the premise that treatment, whether chemotherapy or immunotherapy, is more effective when the tumor cell population is small and host immune and other resistance mechanisms are still intact. To date, randomized trials using dacarbazine, nitrosoureas, a variety of combination chemotherapy regimens, BCG, Corynebacterium parvum, transfer factor, and combinations of immunotherapy and chemotherapy have not demonstrated any advantage for treatment.
Adjuvant treatment for melanoma should be considered whenever possible within clinical research protocols that seek to improve on the results of current standard therapy in a systematic manner. Patients with a high risk of recurrence and death due to melanoma in the first several years following surgery include those patients with AJCC stage III melanoma (positive regional lymph node pathology) or those with deep primary invasion (greater than 4 mm Breslow depth). Patients in these two categories have at least a 50% chance of recurrence and death within 5 years of their diagnosis with just observation and are candidates for adjuvant trials. Investigations over the past decade have focused upon the interferons in this category of high-risk melanoma, and four trials conducted in this interval have recently been published or presented in national and international forums. The Eastern Cooperative Oncology Group has completed a trial of adjuvant therapy with high-dose IFN- alpha2b compared versus observation in stage IIb or III (AJCC) patients, the results of which have served as a pivotal basis for Food and Drug Administration (FDA) approval of IFN- alpha2b for the adjuvant treatment of high-risk melanomas. The treatment protocol adopted for this early trial is notable for its use of an initial month of daily intravenous therapy at 20 MU/m2 /d for 5 days a week for 4 weeks. This 1-month period of induction therapy was designed to deliver peak levels of circulating interferon- alpha unattainable by other routes, and was followed by 11 months of subcutaneous therapy at 10 MU/m2 three times a week, designed to sustain maximal tolerable levels of interferon in an outpatient or home therapy setting. An analysis of 280 of 287 patients for whom full data were available has demonstrated a significant prolongation of median time to relapse (1.7 versus 0.98 years, P2 = .005) and overall survival (3.8 versus 2.8 years, P2 = .047). Treatment was associated with an increment in the 5-year survival from 36% to 47%, and with an increment in the 5-year continuous relapse-free survival from 26% to 37%. These data have suggested the possibility of a curative impact of therapy with IFN- alpha2b as given in this trial. Cox multivariate analysis of this trial showed IFN therapy to be a highly significant independent prognostic factor and, after stage of disease, the most significant favorable prognostic factor.
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Toxicity of this therapy is significant, with nearly ubiquitous flulike symptoms of moderate to severe degree, and the need for dose delay or attenuation in more than one-third of patients during induction, and again during the subcutaneous maintenance phase of treatment. The completion of 1 year of therapy was feasible in the majority (74%) of patients who did not experience progression. Proper attention to hematologic and hepatic function has been sufficient to avoid lethal hepatic toxicities observed early during the application of this intensive protocol. The ECOG has led an intergroup confirmatory sequel study (E1690/SWOG9111/CALGB9190) that completed accrual in mid-1995 and will require up to several years of maturity for evaluation. This protocol was designed not only to corroborate E1684 but also to test the influence of a lower dose of IFN- alpha2b, 3 MU/d given subcutaneously three times weekly for 2 years. It closed in 1995 with accrual of 642 patients. This Intergroup Trial differed from the initial trial E1684 in that lymph node dissection was no longer required for patients with T4 (greater than 4.0 mm) primary melanomas.