In a recent issue of Cancer Research, researchers from the University of Pennsylvania showed for the first time that engineered human T cells can eradicate deadly human ovarian cancer in immune-deficient mice. A clinical trial involving the modified T cells is expected to be announced within the next few months.
In a recent issue of Cancer Research, Daniel J. Powell, Jr., Ph.D., a research assistant professor of Pathology and Laboratory Medicine at the Perelman School of Medicine at the University of Pennsylvania, showed for the first time that engineered human T cells can eradicate deadly human ovarian cancer in immune-deficient mice. Ovarian cancer is the most lethal reproductive cancer for women, with one-fifth of women diagnosed with advanced disease surviving five years. Nearly all ovarian cancers (90%) are characterized by their expression of a distinct cell-surface protein called alpha-folate receptor, which can be targeted by engineered T cells.
The alpha-folate receptor is expressed on the surface of ovarian cancer cells and has a high affinity for folic acid, a vitamin which helps “feed” the cancer cells, and represents an “Achilles’ Heel” for cancer researchers to target.
Until now, human T cells engineered to express an antibody fragment specific for the alpha-folate receptor protein have shown anti-tumor activity against epithelial cancers in the lab, but not in the clinic due to their inability to persist and attack tumors in the human body. The modified T cells used in this study express an engineered fusion protein – called a “chimeric antigen receptor” (CAR) — that combines the specificity of an antibody with the T cell signaling portions from two different proteins that stimulate the immune system to recognize ovarian cancer cells. These added signaling protein pieces give the engineered T cells the extra survival signals they need to do their job.
In a past clinical study, first generation engineered T cells did not shrink tumors in women with ovarian cancer because the T cells did not persist in the patients. The new second generation technology developed in the current study overcomes the limitations of the first generation approach. Specifically, the second generation T cells shrank tumors in mice, but the T cells engineered using first generation technology did not. The second generation T cells also caused tumor regression in models of metastatic intraperitoneal, subcutaneous, and lung-involved human ovarian cancer.
“We anticipate the opening of a genetically modified T cell clinical trial in the next few months for women with recurrent ovarian cancer,” said Powell. “Targeting the alpha-folate receptor is an opportunity for widespread clinical application.”
Two Birds, One Stone T Cells
The double-barreled T cells are engineered to multiply, survive, recognize, and kill ovarian tumors. The modified T cells were expanded for two weeks in the lab, and then tested for reactivity by exposing them to human ovarian cancer cells to see if they destroyed the cancer cells. Researchers also tested for effectiveness by measuring cytokine production by the T cells, a sign of inflammation produced by the engineered T cells when killing cancer cells.
The new second generation engineered T cells were successful in many ways. First, they were resistant to cancer-induced cell death; that is, fewer new T cells died when exposed to cancer cells, compared to the older technology. Second, the new T cells also multiplied better and survived; therefore their numbers increased over time in in vitro experiments and in the mouse model.
A clinical trial using these T cells is pending with George Coukos, M.D., Director of the Ovarian Cancer Research Center at Penn and the principal trial investigator. Penn is the only study site identified to date. Investigators aim to recruit up to 21 patients with advanced recurrent ovarian cancer whose tumors express the alpha-folate receptor.
“This technology represents a promising advancement for the treatment of women with ovarian cancer,” said Powell. “But we will continue to work around the clock to improve this approach using other costimulatory portions and antibody-like proteins to make this the most powerful and safe approach for the treatment of the greatest number of women with this horrible disease.”
About Penn Medicine
Penn Medicine is one of the world’s leading academic medical centers, dedicated to the related missions of medical education, biomedical research, and excellence in patient care. Penn Medicine consists of the Raymond and Ruth Perelman School of Medicine at the University of Pennsylvania (founded in 1765 as the nation’s first medical school) and the University of Pennsylvania Health System, which together form a $4 billion enterprise.
Penn Medicine is committed to improving lives and health through a variety of community-based programs and activities. In fiscal year 2010, Penn Medicine provided $788 million to benefit the community.
About Perelman School of Medicine, University of Pennsylvania
Penn’s Perelman School of Medicine is currently ranked #2 in U.S. News & World Report’s survey of research-oriented medical schools and among the top 10 schools for primary care. The School is consistently among the nation’s top recipients of funding from the National Institutes of Health, with $507.6 million awarded in the 2010 fiscal year.
About University of Pennsylvania Health System
The University of Pennsylvania Health System’s patient care facilities include: The Hospital of the University of Pennsylvania — recognized as one of the nation’s top 10 hospitals by U.S. News & World Report; Penn Presbyterian Medical Center; and Pennsylvania Hospital – the nation’s first hospital, founded in 1751. Penn Medicine also includes additional patient care facilities and services throughout the Philadelphia region.
Song DG, et al. In Vivo Persistence,Tumor Localization, and Antitumor Activity of CAR-Engineered T Cells Is Enhanced by Costimulatory Signaling through CD137 (4-1BB). Cancer Res. 2011 Jul 1;71(13):4617-27. Epub 2011 May 5. PubMed PMID: 21546571.
Penn Study Finds More Effective Approach Against “Achilles’ Heel” of Ovarian Cancer, News Brief, Penn Medicine, Perelman School of Medicine, University of Pennsylvania Health System, August 5, 2011.