Marking a path to transplant tolerance

Ambovex(®) as a novel immunological modulator drug for the treatment of hepatocellular carcinoma (HCC) in the liver: a Phase II clinical trial

Hepatocellular carcinoma (HCC) is a global public health problem, based on it being the fifth most common cancer and third leading cause of cancer-related mortality worldwide. The approved conventional treatment methods for HCC have shown life-threatening side effects with limited or negligible success, especially in multifocal HCC. As a consequence, new therapeutic approaches are being explored, including immunoregulatory molecules that may have the potential to treat or delay the progression of HCC. A novel pharmaceutical botanical drug - Ambovex(®), an immune-modulator molecule - was tested to treat or delay the progress of HCC. We conducted a 6-month randomized clinical trial with an additional 3-month washing period (no treatment) to evaluate the safety and efficacy of low-dose Ambovex oral spray in treating patients with HCC. The clinical study involved a total of 40 patients, with 33 in the treatment group and seven in the control group. The α-fetoprotein (AFP) levels were measured every month and ultrasound scans were performed at time zero and every 2 months thereafter. Computed tomography (CT) scans were performed for patients in the treatment group. Ambovex proved to be safe, as there were no significant side effects although some patients found that the drug has unpleasant taste. AFP analysis showed a significant decrease in its level (α=0.05; 95% confidence interval) in the treatment group when compared to the control group at 3 months (P=0.0031) and at 6 months (P=0.007). The ultrasound results showed improvement in the treated group, as evidenced by a significant decrease in the lesion numbers and sizes. The lesions in 38% of treated patients decreased from multiple to single with major improvements; 35% of patients exhibited a decrease from multiple lesions to multiple lesions with minor improvements, whereas 27% had stabilized lesions. CT scans in the treated group showed significant improvement, as there was complete disappearance of the lesions after 6 months of treatment with Ambovex in two patients. This clinical study showed the effective and promising results of Ambovex as an immunological modulator in treating HCC. Further exploration of Ambovex is recommended.

Manipulating Immune Tolerance with Micro-RNA Regulated Gene Therapy

The success of in vivo gene therapy greatly depends on the ability to control the immune response toward the therapeutic transgene. Over the last decade several vector-based and pharmacological approaches have been explored to control the immune-mediated clearance of transgene-expressing cells after viral delivery. One important outcome from these studies is the concept that expression of a transgene in tolerance-promoting organs, such as the liver and tolerogenic antigen-presenting cells, can help safeguard transgene-expressing cells from immune-mediated clearance. Gene therapists are now manipulating vectors to target naturally occurring tolerogenic properties of the body by: (i) incorporating tissue/cell specific promoters for targeted expression, (ii) using viral-capsid engineering to alter tropism and avoid pre-existing immunity, and (iii) regulating cell and activation dependent expression by including micro-RNA (miR) targets into expression cassettes. The combination of these three layers of vector regulation greatly enhances the targeting of tolerogenic cells and limits off-target expression of the transgene, which can lead to the induction of transgene-specific pathogenic effector T cells. In this review, we discuss the application of using miR transgene regulation to generate tolerogenic responses and speculate on possible mechanisms used by the liver to induce the transgene-specific regulatory T cells.

Identification of a B cell signature associated with renal transplant tolerance in humans

Establishing long-term allograft acceptance without the requirement for continuous immunosuppression, a condition known as allograft tolerance, is a highly desirable therapeutic goal in solid organ transplantation. Determining which recipients would benefit from withdrawal or minimization of immunosuppression would be greatly facilitated by biomarkers predictive of tolerance. In this study, we identified the largest reported cohort to our knowledge of tolerant renal transplant recipients, as defined by stable graft function and receiving no immunosuppression for more than 1 year, and compared their gene expression profiles and peripheral blood lymphocyte subsets with those of subjects with stable graft function who are receiving immunosuppressive drugs as well as healthy controls. In addition to being associated with clinical and phenotypic parameters, renal allograft tolerance was strongly associated with a B cell signature using several assays. Tolerant subjects showed increased expression of multiple B cell differentiation genes, and a set of just 3 of these genes distinguished tolerant from nontolerant recipients in a unique test set of samples. This B cell signature was associated with upregulation of CD20 mRNA in urine sediment cells and elevated numbers of peripheral blood naive and transitional B cells in tolerant participants compared with those receiving immunosuppression. These results point to a critical role for B cells in regulating alloimmunity and provide a candidate set of genes for wider-scale screening of renal transplant recipients.

Immunotherapy for liver tumors: present status and future prospects

Increasing evidence suggests that immune responses are involved in the control of cancer and that the immune system can be manipulated in different ways to recognize and attack tumors. Progress in immune-based strategies has opened new therapeutic avenues using a number of techniques destined to eliminate malignant cells. In the present review, we overview current knowledge on the importance, successes and difficulties of immunotherapy in liver tumors, including preclinical data available in animal models and information from clinical trials carried out during the lasts years. This review shows that new options for the treatment of advanced liver tumors are urgently needed and that there is a ground for future advances in the field.