Follow-up analysis of a randomized phase III immunotherapeutic clinical trial on melanoma

A systematic analysis on the clinical safety and efficacy of onco-virotherapy

Several onco-virotherapy candidates have been developed and clinically evaluated for the treatment of cancer, and several are approved for clinical use. In this systematic review we explored the clinical impact of onco-virotherapy compared to other cancer therapies by analyzing factors such as trial design, patient background, therapy design, delivery strategies, and study outcomes. For this purpose, we retrieved clinical studies from three platforms: ClinicalTrials.gov, PubMed, and EMBASE. We found that most studies were performed in patients with advanced and metastatic tumors, using a broad range of genetically engineered vectors and mainly administered intratumorally. Therapeutic safety was the most frequently assessed outcome, while relatively few studies focused on immunological antitumor responses. Moreover, only 59 out of 896 clinical studies were randomized controlled trials reporting comparative data. This systemic review thus reveals the need of more, and better controlled, clinical studies to increase our understanding on the application of onco-virotherapy either as a single treatment or in combination with other cancer immunotherapies.

Vaccine Therapies for Cancer: Then and Now

There are strong biologic and preclinical rationales for the development of therapeutic cancer vaccines; however, the clinical translation of this treatment strategy has been challenging. It is now understood that many previous clinical trials of cancer vaccines used target antigens or vaccine designs that inherently lacked sufficient immunogenicity to induce clinical responses. Despite the historical track record, breakthrough advances in cancer immunobiology and vaccine technologies have supported continued interest in therapeutic cancer vaccinations, with the hope that next-generation vaccine strategies will enable patients with cancer to develop long-lasting anti-tumor immunity. There has been substantial progress identifying antigens and vaccine vectors that lead to strong and broad T cell responses, tailoring vaccine designs to achieve optimal antigen presentation, and finding combination partners employing complementary mechanisms of action (e.g., checkpoint inhibitors) to overcome the diverse methods cancer cells use to evade and suppress the immune system. Results from randomized, phase 3 studies testing therapeutic cancer vaccines based on these advances are eagerly awaited. Here, we summarize the successes and failures in the clinical development of cancer vaccines, address how this historical experience and advances in science and technology have shaped efforts to improve vaccines, and offer a clinical perspective on the future role of vaccine therapies for cancer.

Systemic adjuvant therapy for adult patients at high risk for recurrent melanoma: A systematic review

Cutaneous melanoma is typically treated with wide local excision and, when appropriate, a sentinel node biopsy. Many patients are cured with this approach but for patients who have cancers with high risk features there is a significant risk of local and distant relapse and death. Interferon-based adjuvant therapy was recommended in the past but had modest results with significant toxicity. Recently, new therapies (immune checkpoint inhibitors and targeted therapies) have been found to be effective in the treatment of patients with metastatic melanoma and many of these therapies have been evaluated and found to be effective in the adjuvant treatment of high risk patients with melanoma. This systematic review of adjuvant therapies for cutaneous and mucosal melanoma was conducted for Ontario Health (Cancer Care Ontario) as the basis of a clinical practice guideline to address the question of whether patients with completely resected melanoma should be considered for adjuvant systemic therapy and which adjuvant therapy should be used.

An Open-Label Study of the Safety and Efficacy of Tag-7 Gene-Modified Tumor Cells-Based Vaccine in Patients with Locally Advanced or Metastatic Malignant Melanoma or Renal Cell Cancer

LESSONS LEARNED

This study showed that carefully selected patients with locally advanced and metastatic forms of malignant melanoma and renal cell carcinoma could potentially have long-term disease control with a tag-7 gene-modified tumor cells-based vaccine. Randomized clinical trials in patients whose tumors produce low amounts of immunosuppressive factors are needed to confirm this hypothesis in both the adjuvant and metastatic settings.

BACKGROUND

Immunotherapy may produce long-lasting effects on survival and toxicity. The magnitude of efficacy may be dependent on immune factors. We analyzed the results of a phase I/II study of a tag-7 gene-modified tumor cells-based vaccine (GMV) in patients with malignant melanoma (MM) or renal cell carcinoma (RCC) with biomarker analysis of immunosuppressive factors (ISFs) production by their tumor cells.

METHODS

From 2001 to 2014, 80 patients received GMV: 68 with MM and 12 with RCC. Treatment in the metastatic setting included 61 patients (MM, 51; RCC, 10), and treatment in the adjuvant setting (after complete cytoreduction) included 19 patients (MM, 17; RCC, 2). Twenty-six patients were stage III (33%), and 54 (67%) were stage IV. The patients' tumor samples were transferred to culture, transfected with tag-7 gene, and inactivated by radiation. The produced product was injected subcutaneously every 3 weeks until progression or 2 years of therapy. ISFs were measured in the supernatants of the tumor cell cultures and used as predictive factors.

RESULTS

No major safety issues or grade 5 adverse events (AEs) were seen. One grade 4 and two grade 3 AEs were registered. No AEs were registered in 89.4% of treatment cycles. No delayed AE was found. The 5-year overall survival (OS) in the intention-to-treat population was 25.1%. There were no differences between MM OS and RCC OS (log rank, p = .44). Median OS in the metastatic setting was 0.7 years and in the adjuvant setting was 3.1 years. Classification trees were built on the basis of ISF production (Fig. 1). The median OS was 6.6 years in the favorable prognosis (FP) group (major histocompatibility complex class I polypeptide-related sequence A [MICA] level ≤582 pg/mL, n = 15) and 4.6 months in the unfavorable (UF) group (MICA level >582 pg/mL, n = 12; p < .0001). No significant differences were found between classification trees based on ISFs (transforming growth factor β1 [TGF-β1], interleukin-10 [IL-10], and vascular endothelial growth factor [VEGF]). In patients with stage III-IV MM with FP, median OS was 2.3 years, with 31% patients alive at 10 years (Fig. 2) in the UF group (0.4 years; log rank, p = 1.94E-5). No FP patients received modern immunotherapy.

CONCLUSION

GMV showed high results in carefully selected patients with low ISF (TGF-β1, IL-10, and VEGF) production. The method should be further investigated in patients with FP.

Therapeutic vaccination immunomodulation: forming the basis of all cancer immunotherapy

Recent immunotherapy advances have convincingly demonstrated complete tumour removal with long-term survival. These impressive clinical responses have rekindled enthusiasm towards immunotherapy and tumour antigen vaccination providing 'cures' for melanoma and other cancers. However, many patients still do not benefit; sometimes harmed by severe autoimmune toxicity. Checkpoint inhibitors (anti-CTLA4; anti-PD-1) and interleukin-2 (IL-2) are 'pure immune drivers' of pre-existing immune responses and can induce either desirable effector-stimulatory or undesirable inhibitory-regulatory responses. Why some patients respond well, while others do not, is presently unknown, but might be related to the cellular populations being 'driven' at the time of dosing, dictating the resulting immune response. Vaccination is in-vivo immunotherapy requiring an active host response. Vaccination for cancer treatment has been skeptically viewed, arising partially from difficulty demonstrating clear, consistent clinical responses. However, this article puts forward accumulating evidence that 'vaccination' immunomodulation constitutes the fundamental, central, intrinsic property associated with antigen exposure not only from exogenous antigen (allogeneic or autologous) administration, but also from endogenous release of tumour antigen (autologous) from in-vivo tumour-cell damage and lysis. Many 'standard' cancer therapies (chemotherapy, radiotherapy etc.) create waves of tumour-cell damage, lysis and antigen release, thus constituting 'in-vivo vaccination' events. In essence, whenever tumour cells are killed, antigen release can provide in-vivo repeated vaccination events. Effective anti-tumour immune responses require antigen release/supply; immune recognition, and immune responsiveness. With better appreciation of endogenous vaccination and immunomodulation, more refined approaches can be engineered with prospect of higher success rates from cancer therapy, including complete responses and better survival rates.

Immunotherapy Plus Cryotherapy: Potential Augmented Abscopal Effect for Advanced Cancers

Since the 1920s the gold standard for treating cancer has been surgery, which is typically preceded or followed with chemotherapy and/or radiation, a process that perhaps contributes to the destruction of a patient’s immune defense system. Cryosurgery ablation of a solid tumor is mechanistically similar to a vaccination where hundreds of unique antigens from a heterogeneous population of tumor cells derived from the invading cancer are released. However, releasing tumor-derived self-antigens into circulation may not be sufficient enough to overcome the checkpoint escape mechanisms some cancers have evolved to avoid immune responses. The potentiated immune response caused by blocking tumor checkpoints designed to prevent programmed cell death may be the optimal treatment method for the immune system to recognize these new circulating cryoablated self-antigens. Preclinical and clinical evidence exists for the complementary roles for Cytotoxic T-lymphocyte-associated protein (CTLA-4) and PD-1 antagonists in regulating adaptive immunity, demonstrating that combination immunotherapy followed by cryosurgery provides a more targeted immune response to distant lesions, a phenomenon known as the abscopal effect. We propose that when the host’s immune system has been “primed” with combined anti-CTLA-4 and anti-PD-1 adjuvants prior to cryosurgery, the preserved cryoablated tumor antigens will be presented and processed by the host’s immune system resulting in a robust cytotoxic CD8⁺ T-cell response. Based on recent investigations and well-described biochemical mechanisms presented herein, a polyvalent autoinoculation of many tumor-specific antigens, derived from a heterogeneous population of tumor cancer cells, would present to an unhindered yet pre-sensitized immune system yielding a superior advantage in locating, recognizing, and destroying tumor cells throughout the body.

PLX4032 Mediated Melanoma Associated Antigen Potentiation in Patient Derived Primary Melanoma Cells

Over expression of various immunogenic melanoma associated antigens (MAAs) has been exploited in the development of immunotherapeutic melanoma vaccines. Expression of MAAs such as MART-1 and gp100 is modulated by the MAPK signaling pathway, which is often deregulated in melanoma. The protein BRAF, a member of the MAPK pathway, is mutated in over 60% of melanomas providing an opportunity for the identification and approval by the FDA of a small molecule MAPK signaling inhibitor PLX4032 that functions to inactivate mutant BRAF(V600E). To this end, we characterized five patient derived primary melanoma cell lines with respect to treatment with PLX4032. Cells were treated with 5μM PLX4032 and harvested. Western blotting analysis, RT-PCR and in vitro transwell migration and invasion assays were utilized to determine treatment effects. PLX4032 treatment modulated phosphorylation of signaling proteins belonging to the MAPK pathway including BRAF, MEK, and ERK and abrogated cell phenotypic characteristics such as migration and invasion. Most significantly, PLX4032 led to an up regulation of many MAA proteins in three of the four BRAF mutated cell lines, as determined at the protein and RNA level. Interestingly, MAGE-A1 protein and mRNA levels were reduced upon PLX4032 treatment in two of the primary lines. Taken together, our findings suggest that the BRAF(V600E) inhibitor PLX4032 has therapeutic potential over and above its known target and in combination with specific melanoma targeting vaccine strategies may have further clinical utility.

Long-term outcomes of helper peptide vaccination for metastatic melanoma

OBJECTIVE

The objective of this study was to compare the long-term outcome of patients with metastatic melanoma vaccinated with 6MHP to that of a group of unvaccinated historical controls.

BACKGROUND

A multipeptide vaccine (6MHP), designed to induce helper T cells against melanocytic and cancer-testis antigens, has been shown to induce specific Th1-dominant CD4+ T cell responses.

METHODS

The 6MHP vaccine was administered to patients with metastatic melanoma. Circulating CD4+ T cell responses were measured by proliferation or direct IFN-gamma ELIspot assay. Overall survival of vaccinated patients was compared to a group of clinically comparable historical controls using multivariable Cox regression analysis and Kaplan-Meier survival analysis, taking into account age, metastatic site, and resection status.

RESULTS

Across 40 vaccinated patients and 87 controls, resection status (HR 0.54, P = 0.004) and vaccination (HR 0.24, P < 0.001) were associated with improved overall survival. Forty pairs of vaccinated patients and controls were matched by metastatic site, resection status, and age within 10 years. Median survival was significantly longer for vaccinated patients (5.4 vs 1.3 years, P < 0.001). Among the vaccinated patients, the development of a specific immune response after vaccination was associated with improved survival (HR 0.35, P = 0.040).

CONCLUSIONS

Helper peptide vaccination is associated with improved overall survival among patients with metastatic melanoma. These data support a randomized prospective trial of the 6MHP vaccine.

Melanoma vaccines: mixed past, promising future

Cancer vaccines were one of the earliest forms of immunotherapy to be investigated. Past attempts to vaccinate against cancer, including melanoma, have mixed results, showing the complexity of what was believed to be a simple concept. However, several recent successes and the combination of improved knowledge of tumor immunology and the advent of new immunomodulators make vaccination a promising strategy for the future.