BAT mAb induces lymphopoiesis in nude mice

A Mini-Review for Cancer Immunotherapy: Molecular Understanding of PD-1/PD-L1 Pathway & Translational Blockade of Immune Checkpoints

Interference of the binding of programmed cell death protein 1 (PD-1) and programmed death-ligand 1 (PD-L1) has become a new inspiring immunotherapy for resisting cancers. To date, the FDA has approved two PD-1 monoclonal antibody drugs against cancer as well as a monoclonal antibody for PD-L1. More PD-1 and PD-L1 monoclonal antibody drugs are on their way in clinical trials. In this review, we focused on the mechanism of the PD-1/PD-L1 signaling pathway and the monoclonal antibodies (mAbs) against PD-1 and PD-L1, which were approved by the FDA or are still in clinical trials. And also presented is the prospect of the PD-1/PD-L1 immune checkpoint blockade in the next generation of immunotherapy.

Improving therapeutic activity of anti-CD20 antibody therapy through immunomodulation in lymphoid malignancies

Nearly two decades ago rituximab heralded a new era in management of B cell malignancies significantly increasing response rates and survival. However, despite clear therapeutic advantage, significant numbers of patients become refractory to anti-CD20 mAb therapy, suggesting urgent improvements are required. It is now well recognized that the suppressive tumor microenvironment plays an important role in the outcome of anti-CD20 mAb therapy and that manipulation of this environment may improve the efficacy and produce long-term tumor control. The past few years have seen a surge of interest in immunomodulatory agents capable of overwriting immune suppressive networks into favorable clinical outcome. Currently, a number of such combinations with anti-CD20 mAb is under evaluation and some have produced encouraging outcomes in rituximab refractory disease. In this review, we give an outline of anti-CD20 mAbs and explore the combinations with immunomodulatory agents that enhance antitumor immunity through targeting stimulatory or inhibitory pathways and have proven potential to synergize with anti-CD20 mAb therapy. These agents, primarily mAbs, target CTLA-4, PD-1/PD-L1, and CD40.

Clinical Development of Immune Checkpoint Inhibitors

Recent progress in cancer immunotherapy has been remarkable. Most striking are the clinical development and approval of immunomodulators, also known as immune checkpoint inhibitors. These monoclonal antibodies (mAb) are directed to immune checkpoint molecules, which are expressed on immune cells and mediate signals to attenuate excessive immune reactions. Although mAbs targeting tumor associated antigens, such as anti-CD20 mAb and anti-Her2 mAb, directly recognize tumor cells and induce cell death, immune checkpoint inhibitors restore and augment the antitumor immune activities of cytotoxic T cells by blocking immune checkpoint molecules on T cells or their ligands on antigen presenting and tumor cells. Based on preclinical data, many clinical trials have demonstrated the acceptable safety profiles and efficacies of immune checkpoint inhibitors in a variety of cancers. The first in class approved immune checkpoint inhibitor is ipilimumab, an anti-CTLA-4 (cytotoxic T lymphocyte antigen-4) mAb. Two pivotal phase III randomized controlled trials demonstrated a survival benefit in patients with metastatic melanoma. In 2011, the US Food and Drug Administration (FDA) approved ipilimumab for metastatic melanoma. Several clinical trials have since investigated new agents, alone and in combination, for various cancers. In this review, we discuss the current development status of and future challenges in utilizing immune checkpoint inhibitors.

Safety and activity of PD1 blockade by pidilizumab in combination with rituximab in patients with relapsed follicular lymphoma: a single group, open-label, phase 2 trial

BACKGROUND

Endogenous or iatrogenic antitumour immune responses can improve the course of follicular lymphoma, but might be diminished by immune checkpoints in the tumour microenvironment. These checkpoints might include effects of programmed cell death 1 (PD1), a co-inhibitory receptor that impairs T-cell function and is highly expressed on intratumoral T cells. We did this phase 2 trial to investigate the activity of pidilizumab, a humanised anti-PD1 monoclonal antibody, with rituximab in patients with relapsed follicular lymphoma.

METHODS

We did this open-label, non-randomised trial at the University of Texas MD Anderson Cancer Center (Houston, TX, USA). Adult (≥18 years) patients with rituximab-sensitive follicular lymphoma relapsing after one to four previous therapies were eligible. Pidilizumab was administered at 3 mg/kg intravenously every 4 weeks for four infusions, plus eight optional infusions every 4 weeks for patients with stable disease or better. Starting 17 days after the first infusion of pidilizumab, rituximab was given at 375 mg/m(2) intravenously weekly for 4 weeks. The primary endpoint was the proportion of patients who achieved an objective response (complete response plus partial response according to Revised Response Criteria for Malignant Lymphoma). Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00904722.

FINDINGS

We enrolled 32 patients between Jan 13, 2010, and Jan 20, 2012. Median follow-up was 15.4 months (IQR 10.1-21.0). The combination of pidilizumab and rituximab was well tolerated, with no autoimmune or treatment-related adverse events of grade 3 or 4. The most common adverse events of grade 1 were anaemia (14 patients) and fatigue (13 patients), and the most common adverse event of grade 2 was respiratory infection (five patients). Of the 29 patients evaluable for activity, 19 (66%) achieved an objective response: complete responses were noted in 15 (52%) patients and partial responses in four (14%).

INTERPRETATION

The combination of pidilizumab plus rituximab is well tolerated and active in patients with relapsed follicular lymphoma. Our results suggest that immune checkpoint blockade is worthy of further study in follicular lymphoma.

FUNDING

National Institutes of Health, Leukemia and Lymphoma Society, Cure Tech, and University of Texas MD Anderson Cancer Center.

BAT monoclonal antibody immunotherapy of human metastatic colorectal carcinoma in mice

BAT monoclonal antibody exhibited anti-tumor activity mediated by T and NK cells. We have evaluated the efficacy of murine and humanized BAT for the treatment of human colorectal carcinoma liver metastases in nude mice. HM7, a human colorectal carcinoma was injected into the spleen to colonize the liver. A single intravenous administration of both BAT antibodies significantly reduced the number of metastases and liver weights. Histological examinations demonstrated lymphocyte accumulation near remnant tumors and in tumor-free tissues of BAT treated mice. The efficacy of humanized BAT in the regression of hepatic metastases in human colorectal carcinoma has potential clinical use.