News Release
T Cell

PHILADELPHIA—Too many “exhausted” T cells left in the wake of aggressive chemotherapy regimens for patients with advanced chronic lymphocytic leukemia (CLL) make it more challenging for chimeric antigen receptor (CAR) T cell therapy to do its job. Now, a new study from researchers in the Perelman School of Medicine at the University of Pennsylvania shows how to overcome this type of resistance and reinvigorate these T cells with an experimental small molecule inhibitor.

Reporting online today in the Journal of Clinical Investigation, the team shows how the drug, known as JQ1, improved CAR T cell function by inhibiting what is known as the bromodomain and extra terminal (BET) proteins. BET, the researchers showed, can disrupt CAR expression and key acetylated histone functions in T cells in CLL.

The findings demonstrate, for the first time, this mechanism of resistance and present a much-needed target for CLL when treating patients with cellular therapies like CAR. Only a small subset of patients with advanced CLL respond to CAR T cell therapy—compared to 80 percent of acute lymphocytic leukemia patients with advanced disease.

“Why CAR T cells fail to fully attack cancer cells in so many CLL patients is an important question that needs to be answered in order to expand the use of these immunotherapies in CLL and other cancers,” said senior author Joseph A. Fraietta, PhD, an assistant professor of Microbiology at Penn, and member of the Center for Cellular Immunotherapies. “Treating these ‘war weary’ T cells during the CAR T cell engineering process has the potential to boost responses, we’ve shown here. It’s setting the stage for a very promising set of next steps that rationalize further studies, including clinical trials, to prove this approach is safe and feasible.”

Using the small molecule inhibitor and the T cells and CD19 CAR T cells from multiple previously treated patients, the researchers demonstrated that the BET protein plays a role in downregulating CAR expression, and that, if blocked, can diminish CAR cell T cell exhaustion and increase the production of CAR T cells from CLL patients with poor lymphocytes.

Treatment with JQ1 also increased levels of various immunoregulatory cytokines and chemokines previously reported to be produced by CAR T cells in CLL during successful therapy. The array of native immune and CAR cells mirrored those found more typically in patients who do respond.

Given this observed reinvigoration of dysfunctional CLL patient CAR T cells by BET inhibition, the authors suggest that incorporating JQ1 into cellular engineering and expansion processes could lead to a generation of less defective and more potent final CAR T cells for patients.

To what extent the above pathways contribute to the effects of JQ1 on CAR T cells is a focus of ongoing investigations for the research group.

“This work shows us that T cells can be taught new tricks,” said Bruce Levine, PhD, the Barbara and Edward Netter Professor in Cancer Gene Therapy in Penn’s Perelman School of Medicine, and co-author on the study. “That is to say that the methods of manufacturing can be adapted to improve CAR T cell function, so that what would have been exhausted or dysfunctional cells can now be reinvigorated, and potentially lead to better clinical responses in more patients than before.”

This work was supported by the Bob Levis Funding Group, along with the National Institute of Allergy and Infectious Diseases (T32 AI007632), National Cancer Institute (P01 CA214278 575, R01 CA241762 U54 CA244711 576, P30 CA016520-44S3, and P30 CA016520-44S4), National Institute on Aging (U01 AG066100), the National Institute of General Medical Sciences (R01 GM118501), an Emerging Cancer Informatics Center of Excellence award from the Penn Institute for Biomedical Informatics and Abramson Cancer Center, Gabrielle’s Angel Foundation, an Alliance for Cancer Gene Therapy Investigator Award in Cell and Gene Therapy for Cancer, and Novartis.

Editor’s note: Fraietta is a co-founder of DeCART Therapeutics, Inc. and Levine is a co-founder of Tmunity Therapeutics, Inc. The University of Pennsylvania has licensed certain study-related technologies to Novartis. Penn and the inventors of these technologies receive significant financial benefits as a result of this licensing relationship with Novartis.

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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 $8.9 billion enterprise.

The Perelman School of Medicine has been ranked among the top medical schools in the United States for more than 20 years, according to U.S. News & World Report's survey of research-oriented medical schools. The School is consistently among the nation's top recipients of funding from the National Institutes of Health, with $496 million awarded in the 2020 fiscal year.

The University of Pennsylvania Health System’s patient care facilities include: the Hospital of the University of Pennsylvania and Penn Presbyterian Medical Center—which are recognized as one of the nation’s top “Honor Roll” hospitals by U.S. News & World Report—Chester County Hospital; Lancaster General Health; Penn Medicine Princeton Health; and Pennsylvania Hospital, the nation’s first hospital, founded in 1751. Additional facilities and enterprises include Good Shepherd Penn Partners, Penn Medicine at Home, Lancaster Behavioral Health Hospital, and Princeton House Behavioral Health, among others.

Penn Medicine is powered by a talented and dedicated workforce of more than 44,000 people. The organization also has alliances with top community health systems across both Southeastern Pennsylvania and Southern New Jersey, creating more options for patients no matter where they live.

Penn Medicine is committed to improving lives and health through a variety of community-based programs and activities. In fiscal year 2020, Penn Medicine provided more than $563 million to benefit our community.

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