Immunotherapy for malignant melanoma--tracing Ariadne's thread through the labyrinth

BAP31, a promising target for the immunotherapy of malignant melanomas

PURPOSE

Malignant melanoma's (MM) incidence is rising faster than that of any other cancer in the US and the overall survival at 5 years is less than 10%. B cell associated protein 31 (BAP31) is overexpressed in most MMs and might be a promising target for immunotherapy of this disease.

EXPERIMENTAL DESIGN

Firstly, we investigated the expression profiles of human BAP31 (hBAP31) and mouse BAP31 (mBAP31) in human and mouse normal tissues, respectively. The expression level of hBAP31 in human MMs and mBAP31 in B16 melanoma cells was also analyzed. Then we constructed novel mBAP31 DNA vaccines and tested there ability to stimulate mBAP31-specific immune responses and antitumor immunity in B16 melanoma-bearing mice.

RESULTS

For the first time, we found that protein expression of hBAP31 were dramatically upregulated in human MMs when compared with human normal tissues. Predominant protein expression of mBAP31 was found in mouse B16 melanoma cells but not in mouse important organs. When mice were immunized with mBAP31 DNA vaccines, strong cellular response to mBAP31 was observed in the vaccinated mice. CTLs isolated from immunized mice could effectively kill mBAP31-positive target mouse B16 melanoma tumor cells in vitro and vaccination with mBAP31 DNA vaccines had potent anti-tumor activity in therapeutic model using B16 melanoma cells.

CONCLUSIONS

These are the first data supporting a vaccine targeting BAP31 that is capable of inducing effective immunity against BAP31-expressing MMs and will be applicable to human MMs and hBAP31 DNA vaccine warrants investigation in human clinical trials.

Characterization of small spheres derived from various solid tumor cell lines: are they suitable targets for T cells?

T cell based immunotherapy has been investigated in a variety of malignancies and analyses have been mostly founded on in vitro data with tumor cell monolayers. However, three-dimensional (3D) culture models might mimic more closely the 'in vivo' conditions than 2D monolayers. Therefore, we analyzed the expression of tumor-associated antigens (TAA) and of molecules involved in antigen processing and presentation (APM) in tumor spheres, which served as an in vitro model for micrometastasis which might be enriched in tumor propagating cancer stem cells. For enrichment of sphere cells 12 human solid tumor cell lines were cultured in serum-free medium. Expression of a variety of TAA and APM were analyzed by RT-PCR and/or flow cytometry and compared to expression in corresponding adherent bulk cells grown in regular growth medium. Compared to adherent cells, spheres showed equal or higher mRNA expression levels of LMP2, LMP7 and MECL-1, of TAP1 and TAP2 transporters and, surprisingly, also of TAA including differentiation antigens. However, downregulation or loss of HLA-I and HLA-II molecules in spheres was observed in 8 of 10 and 1 of 2 cell lines, respectively, and was unresponsive to stimulation with IFN-γ. Although tumor spheres express TAA and molecules of intracellular antigen processing, they are defective in antigen presentation due to downregulation of HLA surface expression which may lead to immune evasion.

An intra-patient placebo-controlled phase I trial to evaluate the safety and tolerability of intradermal IMM-101 in melanoma

BACKGROUND

IMM-101 is a heat-killed innate and adaptive immune-activating mycobacterial product; a phase I study aimed to determine its safety and tolerability in individuals with melanoma.

PATIENTS AND METHODS

An intra-patient placebo-controlled study evaluated the safety and tolerability of three doses, namely, 0.1 (1 mg/ml), 0.5 (5 mg/ml) and 1.0 mg (10 mg/ml) of IMM-101 in stage III or IV melanoma. Each dose was administered in ascending order to one of the three cohorts.

RESULTS

Based on observations from patients administered the 0.1-mg dose, it was considered appropriate to proceed with dosing the patients in the 0.5-mg dose cohort and then the 1.0-mg cohort (n = 6 per cohort). Treatment-emergent adverse events that would be considered typical of a post-vaccination state (including joint pains/aches, headaches and influenza-like symptoms) occurred at all dose levels, along with injection site reactions. These were mainly mild in intensity, resolved in a matter of days and responded well to supportive care. During post-study follow-up, two clinical responses (15%) were observed in patients with stage IV disease.

CONCLUSION

IMM-101 is safe and well tolerated and there is a rationale for studying IMM-101 at a nominal 1.0-mg dose to complement conventional cytotoxic therapy for patients with advanced cancer.

Therapeutic cancer vaccines: why so few randomised phase III studies reflect the initial optimism of phase II studies

Immunotherapy is showing promise for the treatment of a range of tumours including prostate cancer, melanoma and non small-cell lung cancer. Phase II trial data has been extremely encouraging with regards both clinical outcome and the investigation of the underlying immunological mode-of-action. However, despite the positive phase II data there remains a high failure rate in late stage clinical trials which, in many cases can be ascribed to inappropriate trial design, poor patient selection and inconsistency in patient management. The potential impact of standard cancer treatments and other factors which may vary within patient populations is discussed. A perspective is provided on the failure of late-stage clinical trials across a range of platforms focusing particularly on melanoma and prostate cancer.

Current status and future applications of cellular therapies for cancer

Therapies based on the use of autologous immune cells are among the best candidates for cancer immunotherapy. Dendritic cell vaccines have demonstrated very encouraging responses for some solid tumors, while in melanoma autologous T-cell therapies have exceeded 70% objective response rates in selected Phase I trials. However, it is clear that a number of barriers exist to the effective, practical application of these therapies. The aim of this article is to consider modifications to such strategies over the last 3 years and the resultant clinical research in autologous dendritic cell vaccines, T-cell therapy and γδ T-cell therapy for cancer.

Molecular surgery for the treatment of malignant tumors: bioincompatible material apheresis for cancer therapy?

Controlled immunological shock, induced by bioincompatible material apheresis for cancer (BIC MAC) therapy, produces an immunoactive status in experimental subjects. However, in order to provide a safe, painless, effective, and reproducible BIC MAC therapy, it is mandatory to provide general anesthesia with endotracheal intubation not only during apheresis procedures of 1-h duration but also for an additional 5 h. Using this procedure, there was no mortality experienced during animal experiments. Also, there were no procedurally related physical or sensory abnormalities demonstrated. This general anesthesia of 6 h covered not only the initial 30 min of the hypotension and hypoxic stages but also the recovery stages to hemodynamically normalize the experimental animals. After 6 h, the accumulated leukocytes in the lung are released back to the systemic circulation. In general, granulocytes decreased almost 100% while lymphocytes decreased only 40-50%. During these 6 h, increases of cytokines (tumor necrosis factor-α, interleukin-6, etc.) sometimes up to 1000 times occurred. After the 6-h procedure, leukocytes returned nearly to preoperative levels but tended to be continuously increased. After the fourth day, leukocyte counts more than doubled. These cellular and humoral activations were normalized after 2 weeks. These studies were conducted on six normal mongrel dogs. Currently, similar studies are planned to be conducted on tumor-bearing experimental animals. This procedurally induced immunoactivation by apheresis may be able to produce effective apoptosis in malignant tumor cells.

Can prior vaccinations against certain infections confer protection against developing melanoma?

Currently available, relatively safe vaccines may help tackle this serious and increasing public health problem.