Enhancement of complement-dependent cytotoxicity by polyvalent melanoma cell vaccine (CancerVax): correlation with survival

Melanoma

Melanoma is a common cancer in the Western world with an increasing incidence. Sun exposure is still considered to be the major risk factor for melanoma. The prognosis of patients with malignant (advanced-stage) melanoma differs widely between countries, but public campaigns advocating early detection have led to significant reductions in mortality rates. As well as sun exposure, distinct genetic alterations have been identified as associated with melanoma. For example, families with melanoma who have germline mutations in CDKN2A are well known, whereas the vast majority of sporadic melanomas have mutations in the mitogen-activated protein kinase cascade, which is the pathway with the highest oncogenic and therapeutic relevance for this disease. BRAF and NRAS mutations are typically found in cutaneous melanomas, whereas KIT mutations are predominantly observed in mucosal and acral melanomas. GNAQ and GNA11 mutations prevail in uveal melanomas. Additionally, the PI3K-AKT-PTEN pathway and the immune checkpoint pathways are important. The finding that programmed cell death protein 1 ligand 1 (PDL1) and PDL2 are expressed by melanoma cells, T cells, B cells and natural killer cells led to the recent development of programmed cell death protein 1 (PD1)-specific antibodies (for example, nivolumab and pembrolizumab). Alongside other new drugs - namely, BRAF inhibitors (vemurafenib and dabrafenib) and MEK inhibitors (trametinib and cobimetinib) - these agents are very promising and have been shown to significantly improve prognosis for patients with advanced-stage metastatic disease. Early signs are apparent that these new treatment modalities are also improving long-term clinical benefit and the quality of life of patients. This Primer summarizes the current understanding of melanoma, from mechanistic insights to clinical progress. For an illustrated summary of this Primer, visit: http://go.nature.com/vX2N9s.

Melanoma vaccines

There is much renewed activity in the testing of vaccines that target metastatic melanoma, driven by successes in other areas, most notably prostate cancer. Yet, sound evidence that any stand-alone vaccination approach has clinical benefit against melanoma remains lacking. With phase III studies showing no efficacy of promising whole-cell vaccines and heat shock proteins, peptide and dendritic cell vaccines remain the most common approaches. A major obstacle to progress is the lack of any surrogate measures in phase II studies that associate meaningfully with clinical benefit, and this is further complicated by phase III evidence in prostate cancer that immunologic monitoring, tumor response rates, or even times to tumor progression may not accurately predict survival benefit. The area with the most progress has been in combining vaccines with other systemic immunostimulatory agents. Although no vaccine has been found which fulfills the prediction from murine models that they can enhance the efficacy of ipilimumab, combining a peptide vaccination with high-dose interleukin 2 was shown to enhance complete and overall response rates compared with interleukin 2 alone. These promising combinations continue to struggle with the same unresolved issues that have plagued melanoma vaccines from the beginning-what are the best antigens to target, what are the best methods of vaccination, and what constitutes a sufficient immune response to be of value? Virtually no progress has been made toward answering these questions.

Tumor Cell Vaccines

This chapter reviews the history of tumor cell vaccines, both autologous and allogeneic, as well as adjuvants used with tumor cell vaccines. The chapter discusses various tumor cell modifications that have been tested over the years. The immune response to tumor vaccines is briefly described, as are some methods of immune monitoring after vaccine therapy. Finally, there is a description of various tumor cell-based vaccines that have been tested in clinical trials.

Targeting Melanoma Cells with Human High Molecular Weight-Melanoma Associated Antigen-Specific Antibodies Elicited by a Peptide Mimotope: Functional Effects

Human high molecular weight-melanoma associated Ag (HMW-MAA) mimics have been shown to elicit HMW-MAA-specific humoral immune responses that appear to be clinically beneficial. This finding has stimulated interest in characterizing the mechanism(s) underlying the ability of the elicited Abs to exert an anti-tumor effect. To address this question, in the present study, we have generated HMW-MAA-specific Abs by sequentially immunizing rabbits with the peptide P763.74, which mimics the HMW-MAA determinant recognized by mAb 763.74, and with HMW-MAA(+) melanoma cells. HMW-MAA-specific Abs isolated from immunized rabbits mediated cell-dependent cytotoxicity but did not mediate complement-dependent cytotoxicity of HMW-MAA(+) melanoma cells. These Abs also effectively inhibited spreading, migration and Matrigel invasion of HMW-MAA(+) melanoma cells. Besides contributing to our understanding of the role of HMW-MAA in the biology of melanoma cells, these results suggest that both immunological and nonimmunological mechanisms underlie the beneficial clinical effects associated with the induction of HMW-MAA-specific Abs in melanoma patients immunized with a HMW-MAA mimic.

Cancer vaccines entering Phase III clinical trials

The last 10 years have seen a growth in the number of tumour antigens identified from immune responses raised in patients. The discovery that tumours can be recognised by the immune system stimulated a great deal of work characterising the molecular mechanisms underlying immune recognition. This in turn has led to an impressive array of immunological approaches to the generation of cancer vaccines; these range from molecularly defined T cell epitopes, antibody-based vaccines, cytokine therapies, immune modulators and DNA vaccines, to whole cell vaccines and, more recently, combinations of these methods. Many of these approaches have entered Phase I/II trials and have shown interesting clinical results. Moreover, they have extended our knowledge of the immune system and our understanding of the mechanisms required to design a successful cancer vaccine. This review outlines some of the approaches that have led to some of these vaccines entering Phase III clinical trials, discusses their modes of action and reports on their current status in trial.

Tumor antigens for cancer immunotherapy: therapeutic potential of xenogeneic DNA vaccines

Preclinical animal studies have convincingly demonstrated that tumor immunity to self antigens can be actively induced and can translate into an effective anti-tumor response. Several of these observations are being tested in clinical trials. Immunization with xenogeneic DNA is an attractive approach to treat cancer since it generates T cell and antibody responses. When working in concert, these mechanisms may improve the efficacy of vaccines. The use of xenogeneic DNA in overcoming immune tolerance has been promising not only in inbred mice with transplanted tumors but also in outbred canines, which present with spontaneous tumors, as in the case of human. Use of this strategy also overcomes limitations seen in other types of cancer vaccines. Immunization against defined tumor antigens using a xenogeneic DNA vaccine is currently being tested in early phase clinical trials for the treatment of melanoma and prostate cancers, with proposed trials for breast cancer and Non-Hodgkin's Lymphoma.

Granulocyte-macrophage colony-stimulating factor gene-modified autologous tumor vaccines in non-small-cell lung cancer

To evaluate the feasibility, safety, and efficacy of vaccination with autologous tumor cells genetically modified with an adenoviral vector (Ad-GM) to secrete human granulocyte-macrophage colony-stimulating factor (GM-CSF), we conducted a phase I/II multicenter trial in patients with early and advanced stage non-small-cell lung cancer (NSCLC). Vaccines were generated from autologous tumor harvests. Intradermal injections were given every 2 weeks for a total of three to six vaccinations. Tumors were harvested from 83 patients, 20 with early-stage NSCLC and 63 with advanced- stage NSCLC; vaccines were successfully manufactured for 67 patients, and 43 patients were vaccinated. The most common toxicity was a local injection-site reaction (93%). Three of 33 advanced-stage patients, two with bronchioloalveolar carcinoma, had durable complete tumor responses (lasting 6, 18, and >or=22 months). Longer survival was observed in patients receiving vaccines secreting GM-CSF at more than 40 ng/24 h per 10(6) cells (median survival = 17 months, 95% confidence interval [CI] = 6 to 23 months) than in patients receiving vaccines secreting less GM-CSF (median survival = 7 months, 95% CI = 4 to 10 months) (P =.028), suggesting a vaccine dose-related survival advantage.

Endogenous immune response to early- and intermediate-stage melanoma is correlated with outcomes and is independent of locoregional relapse and standard prognostic factors

BACKGROUND

Standard prognostic factors, including precise staging of the regional lymph nodes, cannot accurately determine which early-stage melanomas will metastasize. The immune response to a 90-kd tumor-associated antigen correlates with occult nodal disease and survival of patients receiving vaccine therapy for melanoma. We hypothesized that this response might have prognostic significance independent of standard prognostic features.

STUDY DESIGN

Patients with primary melanomas 1.01 to 2.00 mm and tumor-negative regional lymph nodes were identified. Group 1 comprised 50 patients who died of metastases within 7 years after complete surgical treatment; group 2 comprised 50 patients who were matched with group 1 for six standard prognostic features but who lived at least 10 years without recurrence. Postoperative sera were analyzed for an immune complex to TA90 and for immunoglobulin-G and immunoglobulin-M antibodies against TA90.

RESULTS

Median thickness of the primary melanoma was 1.40 +/- 0.31 mm and 1.42 +/- 0.32 mm in groups 1 and 2, respectively; median Clark's level of invasion was III in both groups, and 26 patients in each group had ulcerated primaries. Median TA90-IC level and rate of TA90-IC positivity (optical density greater than 0.410) were 0.557 +/- 0.43 and 82%, respectively, in group 1 and 0.305 +/- 0.15 and 18%, respectively, in group 2 (p < 0.001). The anti-TA90 IgM level was significantly elevated in 12% of group 1 (median titer 1:150) and 62% of group 2 (median titer 1:800) (p < 0.001). There was no significant difference in anti-TA90 IgG levels between the two groups.

CONCLUSIONS

A positive TA90-IC level and absence of an anti-TA90 IgM response correlate with distant metastasis when melanoma is low risk or intermediate risk by standard prognostic factors.

Immune responses in cancer

The complex of humoral factors and immune cells comprises two interleaved systems, innate and acquired. Immune cells scan the occurrence of any molecule that it considers to be nonself. Transformed cells acquire antigenicity that is recognized as nonself. A specific immune response is generated that results in the proliferation of antigen-specific lymphocytes. Immunity is acquired when antibodies and T-cell receptors are expressed and up-regulated through the formation and release of lymphokines, chemokines, and cytokines. Both innate and acquired immune systems interact to initiate antigenic responses against carcinomas. A new approach to the treatment of cancer has been immunotherapy, which aims to up-regulate the immune system in order that it may better control carcinogenesis. Currently, several forms of immunotherapy that use natural biological substances to activate the immune system are being explored therapeutically. The various forms of immunotherapy fall into three main categories: monoclonal antibodies, immune response modifiers, and vaccines. While these modalities have individually shown some promise, it is likely that the best strategy to combat cancer may require multiple immunotherapeutic strategies in order to demonstrate benefit in different patient populations. It may be that the best results are obtained with vaccines in combination with a variety of immunotherapy combinations. Another potent strategy may be in combining with more traditional cancer drugs as evidenced from the benefit derived from enhancing the efficacy of chemotherapy with cytokines. Through such concerted efforts, a durable, therapeutic antitumour immune response may be achieved and maintained over the course of a patient's lifespan.

Androgen blockade enhances response to melanoma vaccine

BACKGROUND

Because preclinical studies suggest an interaction between androgens and the immune system, we used a murine model to determine whether androgen blockade with flutamide might enhance the immunogenicity of an irradiated melanoma cell vaccine.

MATERIALS AND METHODS

Forty C57BL/6 male mice were randomly assigned to four treatment groups: flutamide + RPMI (Group A), flutamide + irradiated B16 murine melanoma cells (Group B), placebo + RPMI (Group C), and placebo + irradiated B16 cells (Group D). Splenocyte proliferation and secretion of interleukin-2 and interferon-gamma were assayed after coculturing splenocytes with irradiated B16 cells. Antibody-dependent cellular cytotoxicity (ADCC) against B16 cells was determined using peripheral blood lymphocytes. To examine the effect of treatment on tumor growth, a second set of 40 mice assigned to Groups A, B, C, and D underwent tumor challenge 7 days after the last treatment.

RESULTS

Splenocyte proliferation was significantly higher in the two groups receiving flutamide at 50 mg/kg x 7 days (29% in Groups A and B vs 3% in Group C and 7% in Group D). Secretion of interferon was significantly higher in mice receiving flutamide + irradiated B16 cells (15.2 pg/ml in Group B vs 0, 1.7, and 4 pg/ml in Groups A, C, and D, respectively; P = 0.0024). Differences in interleukin secretion were not significant. ADCC was 26% in Group B vs 15, 8, and 22% in Groups A, C, and D, respectively (P = 0.0001). In the tumor challenge experiment, the rate of survival was 10% higher in mice receiving irradiated B16 + flutamide than in mice receiving irradiated B16 alone.

CONCLUSION

Flutamide can enhance immune responses to an irradiated whole-cell melanoma vaccine. A clinical study of immunotherapeutic androgen blockade is warranted.

Immunotherapy of advanced breast cancer with a heterophilic ganglioside (NeuGcGM3) cancer vaccine

PURPOSE

A heterophilic ganglioside cancer vaccine was developed by combining NeuGcGM3 with the outer membrane protein complex of Neisseria meningitidis to form very small size proteoliposomes (VSSP). A phase I clinical trial was performed to determine safety and immunogenicity of this vaccine.

PATIENTS AND METHODS

Stage III to IV breast cancer patients received up to 15 (200 micro g) doses of the vaccine by intramuscular injection. The first five doses (induction phase) were given at 2-week intervals, with the remaining treatment (maintenance) administered on a monthly basis.

RESULTS

Twenty-one patients, 11 of whom had metastatic disease, were included. Main toxicities included erythema and induration at the injection site, sometimes associated with mild pain, and low-grade fever (World Health Organization grades 1 and 2). All treated patients who completed the induction phase developed anti-NeuGcGM3 antibody titers between 1:1,280 and 1:164,000 immunoglobulin G (IgG), and 1:640 and 1:164,000 IgM. Noteworthy specific IgA antibodies were induced by vaccination in all stage III patients and in three stage IV patients. Serum antibody levels were higher in the stage III patients, with the larger increases observed after week 32. The antiganglioside IgG subclasses were mainly IgG1 and IgG3. Hyperimmune sera increased complement-mediated cytotoxicity versus P3X63 myeloma cells and a marked IgG differential reactivity against human mammary ductal carcinoma samples.

CONCLUSION

NeuGcGM3/VSSP/Montanide ISA 51 is an unusual immunogenic ganglioside vaccine and also seems to be safe in this small trial. Immunologic surrogates of activity indicate that this reagent warrants further investigation.

Active immunotherapy by reinduction with a polyvalent allogeneic cell vaccine correlates with improved survival in recurrent metastatic melanoma

BACKGROUND

We have observed prolonged survival in patients undergoing vaccine reinduction after resection of recurrent metastatic melanoma and adjuvant polyvalent allogenic cell vaccine (PACV) immunotherapy. We hypothesized that reinduction with a more intensive vaccine regimen would re-stimulate specific immune responses that were correlated with survival after recurrence.

METHODS

From 1996 to 1998, 194 patients developed recurrence during adjuvant PACV (CancerVax vaccine) treatment after resection of metastatic melanoma. Recurrent disease was treated with or without vaccine reinduction. Reinduction regimen entailed an increased vaccine frequency and coadministration of two doses of bacille Calmette-Guérin (BCG). PACV Delayed-type hypersensitivity (DTH) responses were prospectively recorded. Survival was defined as the interval from recurrence to death.

RESULTS

Ninety-four patients underwent reinduction immunotherapy. DTH responses to PACV before recurrence increased significantly after reinduction therapy (P =.0001). The median survival time was 37 months for reinduced patients and 17 months for other patients. On multivariate analysis, reinduction status remained a significant prognostic variable (P =.0277). In the reinduction group, there was a significant correlation between PACV DTH responses and survival (P =.0178).

CONCLUSIONS

Reinduction vaccine regimen can enhance immune responses in previously immunized patients and is associated with prolonged survival after recurrence in patients receiving the same active specific immunotherapy.

CancerVax, an allogeneic tumor cell vaccine, induces specific humoral and cellular immune responses in advanced colon cancer

BACKGROUND

The immunogenicity of the polyvalent tumor cell vaccine CancerVax has been correlated with the survival of patients receiving active immunotherapy for melanoma. Because the various antigens expressed on the vaccine are common to colon adenocarcinoma cells, we examined the survival impact of immune responses elicited by CancerVax in patients with advanced colon cancer refractory to standard therapy.

METHODS

Twenty-seven patients with American Joint Committee on Cancer (AJCC) stage IV colorectal adenocarcinoma were entered prospectively into the study. CancerVax was coadministered with bacille Calmette-Guerin (BCG) for the first 2 weeks of vaccine treatment. Blood was drawn at the start of therapy and every 2 weeks thereafter to measure serum titers of immunoglobulin (Ig)G and IgM against TA90 (a 90-kD immunogen common to colon cancer and CancerVax cells) and against purified protein derivative (PPD), a nontumor control antigen. Cellular immune responses were evaluated by delayed-type hypersensitivity (DTH) reaction to vaccine cells and to PPD. Mean follow-up time was 17.5 months.

RESULTS

There was a significant (P = .0001) increase in anti-TA90 IgG and IgM titers and in DTH response to vaccine cells. Humoral and skin responses to TA90 did not correlate with responses to PPD (P = .199 for IgM, P = .958 for IgG, and P = .149 for DTH). This suggests that these responses are not a manifestation of general immune competence. The median overall survival (OS) was 21.9 months for the entire group. Overall survival was higher among patients whose IgMTA90 titer was >800 (P = .003) or whose disease-free interval exceeded 12 months (P = .031). Multivariate Cox regression analysis-using age, sex, disease-free interval, disease status, extent of metastasis, humoral responses, and DTH responses-found only peak IgMTA90 titer to be a significant predictor of overall survival (P = .0365).

CONCLUSIONS

CancerVax can induce measurable humoral and cellular immune responses to tumor-associated antigens in patients with advanced-stage colon cancer. These responses correlate with overall survival. This novel therapeutic regimen for patients with advanced colon cancer merits further investigation.

High-dose interferon alfa-2b significantly prolongs relapse-free and overall survival compared with the GM2-KLH/QS-21 vaccine in patients with resected stage IIB-III melanoma: results of intergroup trial E1694/S9512/C509801

PURPOSE

Vaccine alternatives to high-dose interferon alfa-2b therapy (HDI), the current standard adjuvant therapy for high-risk melanoma, are of interest because of toxicity associated with HDI. The GM2 ganglioside is a well-defined melanoma antigen, and anti-GM2 antibodies have been associated with improved prognosis. We conducted a prospective, randomized, intergroup trial to evaluate the efficacy of HDI for 1 year versus vaccination with GM2 conjugated to keyhole limpet hemocyanin and administered with QS-21 (GMK) for 96 weeks (weekly x 4 then every 12 weeks x 8).

PATIENTS AND METHODS

Eligible patients had resected stage IIB/III melanoma. Patients were stratified by sex and number of positive nodes. Primary end points were relapse-free survival (RFS) and overall survival (OS).

RESULTS

Eight hundred eighty patients were randomized (440 per treatment group); 774 patients were eligible for efficacy analysis. The trial was closed after interim analysis indicated inferiority of GMK compared with HDI. For eligible patients, HDI provided a statistically significant RFS benefit (hazard ratio [HR] = 1.47, P = .0015) and OS benefit (HR = 1.52, P = .009) for GMK versus HDI. Similar benefit was observed in the intent-to-treat analysis (RFS HR = 1.49; OS HR = 1.38). HDI was associated with a treatment benefit in all subsets of patients with zero to > or = four positive nodes, but the greatest benefit was observed in the node-negative subset (RFS HR = 2.07; OS HR = 2.71 [eligible population]). Antibody responses to GM2 (ie, titers > or = 1:80) at days 29, 85, 365, and 720 were associated with a trend toward improved RFS and OS (P2 = .068 at day 29).

CONCLUSION

This trial demonstrated a significant treatment benefit of HDI versus GMK in terms of RFS and OS in melanoma patients at high risk of recurrence.

An overview of cancer immunotherapy

The survival of patients with cancer has improved steadily but incrementally over the last century, with the advent of effective anticancer treatments such as chemotherapy and radiotherapy. However, the majority of patients with metastatic disease will not be cured by these measures and will eventually die of their disease. New and more effective methods of treating these patients are required urgently. The immune system is a potent force for rejecting transplanted organs or microbial pathogens, but effective spontaneous immunologically induced cancer remissions are very rare. In recent years, much has been discovered about the mechanisms by which the immune system recognizes and responds to cancers. The specific antigens involved have now been defined in many cases. Improved adjuvants are available. Means by which cancer cells overcome immunological attack can be exploited and overcome. Most importantly, the immunological control mechanisms responsible for initiating and maintaining an effective immune response are now much better understood. It is now possible to manipulate immunological effector cells or antigen-presenting cells ex vivo in order to induce an effective antitumour response. At the same time, it is possible to recruit other aspects of the immune system, both specific (e.g. antibody responses) and innate (natural killer cells and granulocytes).

Innovations and strategies for the development of anticancer vaccines

In 1893, William Coley reported the spontaneous regression of a soft tissue sarcoma in several patients suffering from acute bacterial infections. Although this observation occurred over a century ago, the concept of anticancer vaccines and the immunotherapy of cancer has only recently seemed plausible. A myriad of specific and non-specific immunostimulatory approaches have been tested throughout the years with only a modicum of success. Most of these approaches were doomed from the outset since they were based on false or inadequate knowledge of tumour immunology. Recent advances in our understanding, most notably the identification of genes encoding for cancer regression antigens, currently permit investigators to pursue a more cogent strategy to develop novel and specific anticancer vaccine approaches. Several of these approaches are currently being tested in clinical trials and have already yielded exciting results. However, a number of immunologic and host obstacles to the successful application of anticancer vaccines remain. This editorial will provide an update on the clinical status of anticancer vaccines and review areas of promising research initiatives.

Does endogenous immune response determine the outcome of surgical therapy for metastatic melanoma?

BACKGROUND

Although the presence of tumor cells in the blood of patients with metastatic melanoma suggests widely disseminated disease, many of these patients enjoy prolonged survival or cure after surgical resection. Our previous study of adjuvant vaccine therapy after complete resection of metastatic melanoma revealed a strong correlation between postoperative survival and elevated antibody titers to a 90-kDa tumor-associated antigen (TA90) expressed by melanoma cells of the vaccine. We hypothesized a similar correlation between postoperative survival and endogenous anti-TA90 antibody titers induced by the patient's melanoma in the absence of postoperative adjuvant immunotherapy.

METHODS

From 1970 to 1996, 64 patients underwent complete resection of distant melanoma metastases and did not receive postoperative adjuvant immunotherapy. Serum collected within 4 months after surgery was tested in a coded and blinded fashion for anti-TA90 IgG and IgM by enzyme-linked immunosorbent assay, and for total IgG and IgM (controls) by radial immunodiffusion.

RESULTS

Median follow-up for the study population was 19 months (range, 3-147 months). There was no significant correlation between anti-TA90 IgG titer and total IgG level (P = .4785), or between anti-TA90 IgM and total IgM (P = .0989). Univariate analysis showed that postoperative anti-TA90 IgM titer as a continuous variable was significantly associated with overall survival (OS); i.e., the higher the anti-TA90 IgM titer, the longer the OS. Using an established cutoff titer of 800, median OS was 42 months for patients with high anti-TA90 IgM titers (n = 28) vs. 9 months for patients with low titers (n = 36) (P = .0001). There was no significant correlation between total IgG/IgM and survival (P = .4107 and .4044, respectively). Multivariate analysis identified anti-TA90 IgM as the most significant independent variable influencing OS after complete resection of distant melanoma metastases (P = .0001).

CONCLUSIONS

We conclude that the endogenous immune response to metastatic melanoma determines the outcome after surgical therapy. Enhancement of this specific immune response may prolong the survival of patients with distant melanoma metastases.