Are BiTEs the "missing link" in cancer therapy?

Antibody-siRNA conjugates: drugging the undruggable for anti-leukemic therapy

INTRODUCTION

Generating effective RNAi-based therapies with the potential to achieve leukemia remission remains critical unmet need. Despite a growing number of leukemia clinical trials, tissue specific delivery of therapeutic siRNA is a major roadblock in translating its clinical potential. The most recent reports in the antibody-siRNA-conjugates (ARCs) field add new dimensions to leukemic therapy, where a covalently ligated therapeutic antisense-RNA with the potential to repress the oncogenic transcript is selectively delivered into the cancer cells. Despite ARC localization to leukemic cells due to high affinity antigen-antibody interactions, multiple challenges exist to unlock the therapeutic potential of siRNA targeting. Areas covered: This review focuses on antibody and siRNA-based therapies for leukemia as well as potential antibody engineering-based strategies to generate an optimal ARC platform. Expert opinion: In vitro and clinical results have revealed that non-targeted delivery and inefficient cellular internalization of therapeutic siRNA are major contributing factors for the lack of efficacy in leukemia patients. Rational antibody design and selective protein engineering with the potential to neutralize siRNA charge, stabilize ARC complex, restrict off-targeted delivery, optimize endosomal escape, and extend serum half-life will generate clinically relevant leukemic therapies that are safe, selective, and effective.

Immunotherapy for prostate cancer: False promises or true hope?

Prostate cancer is the most commonly diagnosed cancer, and the second leading cause of cancer-related death for men in the United States. Despite the approval of several new agents for advanced disease, each of these has prolonged survival by only a few months. Consequently, new therapies are sorely needed. For other cancer types, immunotherapy has demonstrated dramatic and durable treatment responses, causing many to hope that immunotherapies might provide an ideal treatment approach for patients with advanced prostate cancer. However, apart from sipuleucel-T, prostate cancer has been conspicuously absent from the list of malignancies for which immunotherapies have received recent approval from the US Food and Drug Administration. This has left some wondering whether immunotherapy will "work" for this disease. In this review, the authors describe current developments in immunotherapy, including approaches to engage tumor-targeting T cells, disrupt immune regulation, and alter the immunosuppressive tumor microenvironment. The authors then describe the recent application of these approaches to the treatment of prostate cancer. Given the Food and Drug Administration approval of 1 agent, and the finding that several others are in advanced stages of clinical testing, the authors believe that immunotherapies offer real hope to improve patient outcomes for men with prostate cancer, especially as investigators begin to explore rational combinations of immunotherapies and combine these therapies with other conventional therapies. Cancer 2016;122:3598-607. © 2016 American Cancer Society.

Harnessing the immune system to improve cancer therapy

Cancer immunotherapy uses the immune system and its components to mount an anti-tumor response. During the last decade, it has evolved from a promising therapy option to a robust clinical reality. Many immunotherapeutic modalities are already approved by the Food and Drug Administration (FDA) for treating cancer patients and many others are in the pipeline for approval as standalone or combinatorial therapeutic interventions, several also combined with standard treatments in clinical studies. The two main axes of cancer immunotherapeutics refer to passive and active treatments. Prominent examples of passive immunotherapy include administration of monoclonal antibodies and cytokines and adoptive cell transfer of ex vivo "educated" immune cells. Active immunotherapy refers, among others, to anti-cancer vaccines [peptide, dendritic cell (DC)-based and allogeneic whole cell vaccines], immune checkpoint inhibitors and oncolytic viruses, whereas new approaches that can further enhance anti-cancer immune responses are also widely explored. Herein, we present the most popular cancer immunotherapy approaches and discuss their clinical relevance referring to data acquired from clinical trials. To date, clinical experience and efficacy suggest that combining more than one immunotherapy interventions, in conjunction with other treatment options like chemotherapy, radiotherapy and targeted or epigenetic therapy, should guide the way to cancer cure.