Adjuvant Bestatin immunotherapy in patients with transitional cell carcinoma of the bladder. Clinical results of a randomized trial

Antiretroviral Drug Repositioning for Glioblastoma

Outcomes for glioblastoma (GBM) remain poor despite standard-of-care treatments including surgical resection, radiation, and chemotherapy. Intratumoral heterogeneity contributes to treatment resistance and poor prognosis, thus demanding novel therapeutic approaches. Drug repositioning studies on antiretroviral therapy (ART) have shown promising potent antineoplastic effects in multiple cancers; however, its efficacy in GBM remains unclear. To better understand the pleiotropic anticancer effects of ART on GBM, we conducted a comprehensive drug repurposing analysis of ART in GBM to highlight its utility in translational neuro-oncology. To uncover the anticancer role of ART in GBM, we conducted a comprehensive bioinformatic and in vitro screen of antiretrovirals against glioblastoma. Using the DepMap repository and reversal of gene expression score, we conducted an unbiased screen of 16 antiretrovirals in 40 glioma cell lines to identify promising candidates for GBM drug repositioning. We utilized patient-derived neurospheres and glioma cell lines to assess neurosphere viability, proliferation, and stemness. Our in silico screen revealed that several ART drugs including reverse transcriptase inhibitors (RTIs) and protease inhibitors (PIs) demonstrated marked anti-glioma activity with the capability of reversing the GBM disease signature. RTIs effectively decreased cell viability, GBM stem cell markers, and proliferation. Our study provides mechanistic and functional insight into the utility of ART repurposing for malignant gliomas, which supports the current literature. Given their safety profile, preclinical efficacy, and neuropenetrance, ARTs may be a promising adjuvant treatment for GBM.

CD13 expression affects glioma patient survival and influences key functions of human glioblastoma cell lines in vitro

CD13 (APN) is an Alanyl-Aminopeptidase with diverse functions. The role of CD13 for gliomas is still unknown. In this study, data of glioma patients obtained by TCGA and CGGA databases were used to evaluate the survival rate and prognostic value of CD13 expression level. Protein expression of CD13 was confirmed by immunofluorescence staining of fresh patient tissues. Eight human glioblastoma cell lines were studied by RT-PCR, Western Blot, immunofluorescence staining and flow cytometry to define CD13 expression. Cell lines with different CD13 expression status were treated with a CD13 inhibitor, bestatin, and examined by MTT, scratch and colony formation assaysas well as by apoptosis assay and Western Blots. Bioinformatics analysis indicated that patients with high expression of CD13 had poor survival and prognosis. Additionally, CD13 protein expression was positively associated with clinical malignant characteristics. Investigated glioblastoma cell lines showed distinct expression levels and subcellular localization of CD13 with intracellular enrichment. Bestatin treatment reduced proliferation, migration and colony formation of glioma cells in a CD13-dependent manner while apoptosis was increased. In summary, CD13 has an impact on glioma patient survival and is important for the main function of specific glioma cells.

Ubenimex activates the E-cadherin-mediated adhesion of a breast cancer cell line YMB-S

It has been reported that ubenimex, a biological response modifier, has a direct anti-tumor effect. To clarify the mechanism involved, we examined the effects of ubenimex on the growth and adhesive property of a breast cancer cell line YMB-S. The cells proliferate in a floating manner without aggregation in normal complete medium. Ubenimex induced cell-cell and cell-surface adhesion of the cells accompanied with growth suppression. E-Cadherin localized at cell-cell contact sites of adhered cells, and anti-E-cadherin antibody inhibited the adhesion. Both Western blot analysis and binding assay disclosed that there was no apparent difference between E-cadherin levels of the cells before and after the treatment with ubenimex. These results indicate that ubenimex inhibits the proliferation of YMB-S cells and augments cell-to-cell adhesion through the induction of E-cadherin-mediated adhesion resulting from the functional activation of pre-expressed but inefficient E-cadherin.

Clinical trials of bestatin for leukemia and solid tumors

A new immunomodulating agent, bestatin (INN: ubenimex) has low toxicity after long-term oral administration and significantly modifies immunological responses. Prolongation of remission duration and survival was achieved in adult acute nonlymphocytic leukemia with bestatin immunotherapy combined with remission maintenance chemotherapy. Patients with myelodysplatic syndrome (MDS) and chronic myelogenous leukemia (CML) responded to bestatin, and it is noted that cytogenetic remission was obtained in CML. MDS and CML are thought to be a family of clonal malignant disorders in which malignant transformations occurs at the level of the pluripotent stem cell. Bestatin may be capable of modifying the biological-proliferative disequilibrium of the disease, and the therapy opens new and promising prospects in the treatment of both MDS and CML. Randomized controlled studies of bestatin immunotherapy were performed in solid tumors including malignant melanoma, carcinoma of the lung, stomach, bladder, head and neck, and esophagus, and therapeutic benefits on disease free-interval or survival were observed in certain types of these cancers. However, the adjuvant activity of bestatin immunotherapy for these cancers should be further investigated to confirm its activity.

Effect of ubenimex on the immune system of patients with hematological malignancies

The effect of in vivo administration of ubenimex (Bestatin) on the immune status of patients with hematological malignancies in remission was studied. Natural killer (NK) cell activities, lymphokine activated killer (LAK) cell activities, production of interferon-gamma (gamma-IFN) and surface antigens of peripheral lymphocytes were examined before and after administration of ubenimex. Analysis of the T, B and NK cell compartment ax conducted by assessing expression of the following antigens: CD3+CD19- (T), CD3-CD19+ (B), CD8+CD11b- (Tc), CD8+CD11b+ (Ts), CD4+Leu8-(Th), CD4+Leu8+(Ti), CD16CD57 (NK) using a 2-color flow cytometric analysis. NK and LAK activity was significantly lower in patients with hematological malignancies as compared to normal subjects. The absolute numbers of lymphocytes and NK cells were also lower than those in healthy controls. The reduced NK and LAK activity, however, was elevated after ubenimex administration. The absolute numbers of helper T cells, cytotoxic T cells and NK cells were also increased after administration of the drug. These findings were not observed in patients treated without ubenimex. Serum levels of IFN-gamma were not markedly changed after ubenimex administration. But peripheral blood mononuclear cells cultured with rIL2 showed appreciable levels of IFN-gamma production, and production increased after ubenimex administration. These results shows that ubenimex is a powerful immunomodulator that augments or restores some immune functions in patients with hematological malignancies.

Review of ubenimex (Bestatin): clinical research

An immunomodulating agent, ubenimex (Bestatin) has low toxicity even after long-term oral administration and brings about significant modifications in immunological response. In a cooperative randomized controlled study of Bestatin immunotherapy for adult acute nonlymphocytic leukemia, prolongation of remission duration and survival was achieved with Bestatin immunotherapy combined with remission maintenance chemotherapy. The significant prolongation of remission duration and survival was seen in the Bestatin group, especially in the elderly patients. Randomized controlled studies of Bestatin immunotherapy were performed in solid tumors including malignant melanoma, carcinoma of the lung, stomach, bladder, head and neck and esophagus, and therapeutic benefits regarding disease free-interval or survival were observed in certain types of the above-mentioned cancers; however, Bestatin immunotherapy for these cancers should be further investigated in large-scale controlled studies to confirm its activity.

Effects of bestatin on the host immunity in patients treated for urogenital cancer

To examine effects of bestatin on the host immunity of patients with urogenital cancer, 54 patients were randomized into 2 groups: bestatin treated and controls. In each group, the patients were divided into 2 subgroups: one which received basic treatment expected to greatly affect host immunity ('invasive treatment') while the other one received other types of basic treatment ('non-invasive treatment'). Peripheral lymphocyte, OKT 4/8 ratio and purified protein derivative (PPD) skin reaction were used as immunological markers. There were significant differences in the 'invasive' treatment group between bestatin treated patients and controls concerning lymphocyte counts and PPD skin reactions and in the 'non-invasive' group concerning lymphocyte counts and OKT 4/8 ratios. These results suggest that bestatin may potentiate host immunity in patients with urogenital cancer. Further studies on larger materials are, however, needed before more definite conclusions can be drawn.

Adjuvant bestatin (Ubenimex) treatment following full-dose local irradiation for bladder carcinoma

The clinical value of adjuvant bestatin (Ubenimex) immunotherapy has been examined in a group of patients with urinary bladder cancer. Patients with non-metastatic transitional cell carcinoma of the bladder, scheduled for full-dose local irradiation therapy (64 Gy), were randomly allocated to adjuvant oral bestatin treatment (30 mg daily for at least 1 year), starting at completion of irradiation, or no bestatin. The trial included 194 evaluable patients with a follow-up period of 1.5-9.5 years. The overall survival of the two groups of patients did not differ statistically significantly (97 patients in each). Subgrouping of the patient material gave no evidence that the clinical efficacy of bestatin is related to sex, tumor category or malignancy grade.

Chemoimmunotherapy with cyclophosphamide and bestatin in experimental metastasis in mice

Bestatin has significant therapeutic activity (even following oral administration) for the treatment of metastatic disease, an activity which is limited by tumor burden. Therefore, the therapeutic potential of bestatin was examined in combination with chemotherapy to determine if there is additive activity for heavy tumor burdens. Bestatin significantly increased therapeutic activity and decreased the myelotoxicity of cyclophosphamide following a single injection of cyclophosphamide or split daily doses. In immune function studies, in tumor-bearing animals, bestatin increased the number of colony-forming units (granulocyte-macrophage) (CFU) and alveolar macrophage tumoricidal activity. However, when bestatin was combined with cyclophosphamide, which depressed bone marrow and macrophage activity, it did not show apparent augmentation of macrophage and NK cell activity, but did significantly increase bone marrow CFU activity. Thus, in combined chemoimmunotherapy, bestatin appears to enhance therapeutic activity by accelerating the recovery of hematopoiesis. We suggest, therefore, that a combination chemotherapy protocol, with oral bestatin, may facilitate myelorestoration following aggressive chemotherapy. The majority of biological response modifiers require parental administration; thus, the identification of an orally active, synthetic immunoaugmenting agent with a defined receptor is of particular interest.