Peptide vaccines for hematological malignancies: a missed promise?

Therapeutic strategies to enhance immune response induced by multiple myeloma cells

Multiple myeloma (MM)as a haematological malignancy is still incurable. In addition to the presence of somatic genetic mutations in myeloma patients, the presence of immunosuppressive microenvironment greatly affects the outcome of treatment. Although the discovery of immunotherapy makes it possible to break the risk of high toxicity and side effects of traditional chemotherapeutic drugs, there are still obstacles of ineffective treatment or disease recurrence. In this review, we discuss therapeutic strategies to further enhance the specific anti-tumor immune response by activating the immunogenicity of MM cells themselves. New ideas for future myeloma therapeutic approaches are provided.

Current Trends in Cancer Immunotherapy

The search for an effective drug to treat oncological diseases, which have become the main scourge of mankind, has generated a lot of methods for studying this affliction. It has also become a serious challenge for scientists and clinicians who have needed to invent new ways of overcoming the problems encountered during treatments, and have also made important discoveries pertaining to fundamental issues relating to the emergence and development of malignant neoplasms. Understanding the basics of the human immune system interactions with tumor cells has enabled new cancer immunotherapy strategies. The initial successes observed in immunotherapy led to new methods of treating cancer and attracted the attention of the scientific and clinical communities due to the prospects of these methods. Nevertheless, there are still many problems that prevent immunotherapy from calling itself an effective drug in the fight against malignant neoplasms. This review examines the current state of affairs for each immunotherapy method, the effectiveness of the strategies under study, as well as possible ways to overcome the problems that have arisen and increase their therapeutic potentials.

Novel treatments to tackle myelofibrosis

INTRODUCTION

Despite the dramatic progress made in the treatment of patients with myelofibrosis since the introduction of the JAK1/2 inhibitor ruxolitinib, a therapeutic option that can modify the natural history of the disease and prevent evolution to blast-phase is still lacking. Recent investigational treatments including immunomodulatory drugs and histone deacetylase inhibitors benefit some patients but these effects have proven modest at best. Several novel agents do show promising activity in preclinical studies and early-phase clinical trials. We will illustrate a snapshot view of where the management of myelofibrosis is evolving, in an era of personalized medicine and advanced molecular diagnostics. Areas covered: A literature search using MEDLINE and recent meeting abstracts was performed using the keywords below. It focused on therapies in active phases of development based on their scientific and preclinical rationale with the intent to highlight agents that have novel biological effects. Expert commentary: The most mature advances in treatment of myelofibrosis are the development of second-generation JAK1/2 inhibitors and improvements in expanding access to donors for transplantation. In addition, there are efforts to identify drugs that target pathways other than JAK/STAT signaling that might improve the survival of myelofibrosis patients, and limit the need for stem-cell transplantation.

Identification of HLA‑A*1101‑restricted cytotoxic T lymphocyte epitopes derived from epidermal growth factor pathway substrate number 8

Epidermal growth factor receptor pathway substrate 8 (EPS8) is critical in the proliferation, progression and metastasis of solid and hematological types of cancer, and thus constitutes an ideal target for cancer immunotherapy. The present study aimed to identify human leukocyte antigen (HLA)‑A*1101‑restricted cytotoxic T lymphocyte (CTL) epitopes from EPS8 and characterize their immunotherapeutic efficacy in vitro. Two computer‑based algorithms were used to predict native EPS8 epitopes with potential high binding affinity to the HLA‑A*1101 molecule, which is the HLA‑A allele with the highest frequency in the Chinese population. The peptide‑induced cytokine production from the CTLs was examined using enzyme‑linked immunosorbent spot analysis. The cytotoxic effects on cancer cells by CTLs primed with the identified peptides were examined using flow cytometry. A total of five peptides, designated as P380, P70, P82, P30 and P529, presented with high affinity towards the HLA‑A*1101 molecule. In response to stimulation by these five peptides, enhanced secretion of interferon‑γ from the CTLs and increased cytolytic capabilities of the CTLs toward cancer cells were noted, with the most potent effects observed from the P380 peptide. Taken together, the present study identified five potential CTL epitopes from EPS8. Among these, P380 presented with the highest therapeutic efficacy in vitro. These peptides may benefit the development of EPS8‑based immunotherapy for the treatment of HLA‑A*1101‑positive hematological malignancies.

Effects of indoleamine 2,3-dioxygenase inhibitor in non-Hodgkin lymphoma model mice

Indoleamine 2,3-dioxygenase (IDO) catalyzes the rate-limiting step in the metabolism of tryptophan along the kynurenine pathway. In tumors, increased IDO activity inhibits proliferation and induces apoptosis of T cells and natural killer cells. We investigated the therapeutic potential of IDO inhibitor 1-methyl-D-tryptophan (D-1MT) with cyclophosphamide (CY) in a mouse model of lymphoma. To examine the effect of D-1MT, mice were killed on day 28. Serum concentrations of L-kynurenine and L-tryptophan were measured by high-performance liquid chromatography. Regulatory T cells (Tregs) were counted by flow cytometry, and mRNA expressions of IDO1, Foxp3, IFN-γ, and COX-2 were examined by quantitative real-time reverse transcription-polymerase chain reaction. D-1MT+CY combination treatment significantly inhibited tumor growth as compared to either treatment alone. There were no significant differences in the serum L-kynurenine/L-tryptophan ratio or the IDO1 expression level in the tumors among the treatment groups. The expression levels of IFN-γ and COX-2 mRNA in tumor-draining lymph nodes (TDLNs) were found to be significantly up-regulated in the CY and D-1MT+CY groups. The number of Tregs in TDLNs in the D-1MT+CY group was significantly lower than that in CY groups on day 17. These results suggest that D-1MT in combination with CY is an effective treatment for lymphoma in a mouse model.

Strategies for the identification of T cell-recognized tumor antigens in hematological malignancies for improved graft-versus-tumor responses after allogeneic blood and marrow transplantation

Allogeneic blood and marrow transplantation (allo-BMT) is an effective immunotherapeutic treatment that can provide partial or complete remission for patients with hematological malignancies. Mature donor T cells in the donor inoculum play a central role in mediating graft-versus-tumor (GVT) responses by destroying residual tumor cells that persist after conditioning regimens. Alloreactivity towards minor histocompatibility antigens (miHA), which are varied tissue-related self-peptides presented in the context of major histocompatibility complex (MHC) molecules on recipient cells, some of which may be shared on tumor cells, is a dominant factor for the development of GVT. Potentially, GVT can also be directed to tumor-associated antigens or tumor-specific antigens that are more specific to the tumor cells themselves. The full exploitation of allo-BMT, however, is greatly limited by the development of graft-versus-host disease (GVHD), which is mediated by the donor T cell response against the miHA expressed in the recipient's cells of the intestine, skin, and liver. Because of the significance of GVT and GVHD responses in determining the clinical outcome of patients, miHA and tumor antigens have been intensively studied, and one active immunotherapeutic approach to separate these two responses has been cancer vaccination after allo-BMT. The combination of these two strategies has an advantage over vaccination of the patient without allo-BMT because his or her immune system has already been exposed and rendered unresponsive to the tumor antigens. The conditioning for allo-BMT eliminates the patient's existing immune system, including regulatory elements, and provides a more permissive environment for the newly developing donor immune compartment to selectively target the malignant cells. Utilizing recent technological advances, the identities of many human miHA and tumor antigenic peptides have been defined and are currently being evaluated in clinical and basic immunological studies for their ability to produce effective T cell responses. The first step towards this goal is the identification of targetable tumor antigens. In this review, we will highlight some of the technologies currently used to identify tumor antigens and anti-tumor T cell clones in hematological malignancies.