Penn’s Genetically Modified T Cells Create Antitumor Effect In Mice With Folate Positive Ovarian Cancer; Clinical Trial Pending

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.

Daniel J. Powell, Jr., Ph.D., Research Assistant Professor of Pathology & Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania.

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.

Sources:

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.

Gene Transfer Therapy Destroys Tumors in Chronic Lymphocytic Leukemia Patients; Holds Promise For Ovarian Cancer

Penn researchers have shown sustained remissions of up to a year among a small group of advanced chronic lymphocytic leukemia (CLL) patients treated with genetically engineered versions of their own T-cells. This genetically-modified “serial killer” T-cell approach could provide a tumor-attack roadmap for the treatment of  ovarian, lung, and pancreatic cancer, as well as myeloma and melanoma.

In a cancer treatment breakthrough 20 years in the making, researchers from the University of Pennsylvania’s Abramson Cancer Center and Perelman School of Medicine have shown sustained remissions of up to a year among a small group of advanced chronic lymphocytic leukemia (CLL) patients treated with genetically engineered versions of their own T-cells.

The protocol involves removing patients’ cells and modifying them in Penn’s vaccine production facility, followed by the infusion of the new cells back into the patient’s body following chemotherapy. This approach also represents a potential tumor-attack roadmap for the treatment of other cancers including those of the lung and ovaries and myeloma and melanoma. The findings, published simultaneously yesterday in the New England Journal of Medicine (NEJM) and Science Translational Medicine, are the first demonstration of the use of gene transfer therapy to create “serial killer” T-cells aimed at cancerous tumors.

Carl June, M.D., Ph.D., Principal Investigator; Director, Translational Research & Professor of Pathology & Laboratory Medicine, Abramson Cancer Center, University of Pennsylvania

David Porter, M.D., Co-Principal Investigator; Director, Blood & Marrow Transplantation & Professor of Medicine, Abramson Cancer Center, University of Pennsylvania

“Within three weeks, the tumors had been blown away, in a way that was much more violent than we ever expected,” said senior author Carl June, M.D., Ph.D., director of Translational Research and a professor of Pathology and Laboratory Medicine in the Abramson Cancer Center, who led the work. “It worked much better than we thought it would.”

The results of the pilot trial of three patients are a stark contrast to existing therapies for CLL. The patients involved in the new study had few treatment options. The only potential curative therapy would have involved a bone marrow transplant, a procedure which requires a lengthy hospitalization and carries at least a 20 percent mortality risk — and even then offers only about a 50 percent chance of a cure, at best.

“Most of what I do is treat patients with no other options, with a very, very risky therapy with the intent to cure them,” says co-principal investigator David Porter, M.D., Professor of Medicine and Director of Blood and Marrow Transplantation. “This approach has the potential to do the same thing, but in a safer manner.”

Secret Ingredients

Dr. June thinks there were several “secret ingredients” that made the difference between the lackluster results that have been seen in previous trials with modified T cells and the remarkable responses seen in the current trial. The details of the new cancer immunotherapy are detailed in Science Translational Medicine.

After removing the patients’ cells, the team reprogrammed them to attack tumor cells by genetically modifying them using a lentivirus vector. The vector encodes an antibody-like protein, called a chimeric antigen receptor (CAR), which is expressed on the surface of the T-cells and designed to bind to a protein called CD19 (Cluster of Differentiation 19).

Once the T-cells start expressing the CAR, they focus all of their killing activity on cells that express CD19, which includes CLL tumor cells and normal B-cells. All of the other cells in the patient that do not express CD19 are ignored by the modified T-cells, which limits side effects typically experienced during standard therapies.

The team engineered a signaling molecule into the part of the CAR that resides inside the cell. When it binds to CD19, initiating the cancer cell death, it also tells the cell to produce cytokines that trigger other T-cells to multiply — building a bigger and bigger army until all of the target cells in the tumor are destroyed.

Vodpod videos no longer available.

Serial Killers

“We saw at least a 1000-fold increase in the number of modified T-cells in each of the patients. Drugs don’t do that,” June says. “In addition to an extensive capacity for self-replication, the infused T-cells are serial killers. On average, each infused T-cell led to the killing of thousands of tumor cells – and overall, destroyed at least two pounds of tumor in each patient.”

The importance of the T-cell self-replication is illustrated in the New England Journal of Medicine paper, which describes the response of one patient, a 64-year old man. Prior to his T-cell treatment, his blood and marrow were replete with tumor cells. For the first two weeks after treatment, nothing seemed to change. Then on day 14, the patient began experiencing chills, nausea, and increasing fever, among other symptoms. Tests during that time showed an enormous increase in the number of T-cells in his blood that led to tumor lysis syndrome, which occurs when a large number of cancer cells die all at once.

By day 28, the patient had recovered from the tumor lysis syndrome –– and his blood and marrow showed no evidence of leukemia.

“This massive killing of tumor is a direct proof of principle of the concept,” Porter says.

The Penn team pioneered the use of the HIV-derived vector in a clinical trial in 2003 in which they treated HIV patients with an antisense version of the virus. That trial demonstrated the safety of the lentiviral vector used in the present work.

The cell culture methods used in this trial reawaken T-cells that have been suppressed by the leukemia and stimulate the generation of so-called “memory” T-cells, which the team hopes will provide ongoing protection against recurrence. Although long-term viability of the treatment is unknown, the doctors have found evidence that months after infusion, the new cells had multiplied and were capable of continuing their “seek-and-destroy” mission against cancerous cells throughout the patients’ bodies.

Moving forward, the team plans to test the same CD19 CAR construct in patients with other types of CD19-positive tumors, including non-Hodgkin’s lymphoma and acute lymphocytic leukemia. They also plan to study the approach in pediatric leukemia patients who have failed standard therapy. Additionally, the team has engineered a CAR vector that binds to mesothelin, a protein expressed on the surface of mesothelioma cancer cells, as well as on ovarian and pancreatic cancer cells.

In addition to June and Porter, co-authors on the NEJM paper include Bruce Levine, Ph.D., Michael Kalos, Ph.D., and Adam Bagg MB, BCh, all from Penn Medicine. Michael Kalos and Bruce Levine are co-first authors on the Science Translational Medicine paper. Other co-authors include Carl June, M.D., Ph.D., David Porter, M.D., Sharyn Katz, M.D., MTR, and Adam Bagg MB, BCh, from Penn Medicine, and Stephan Grupp, M.D., Ph.D., from the Children’s Hospital of Philadelphia.

The work was supported by the Alliance for Cancer Gene Therapy, a foundation started by Penn graduates Barbara and Edward Netter, to promote gene therapy research to treat cancer, and the Leukemia & Lymphoma Society.

Accompanying NEJM Editorial

In an accompanying NEJM editorial, Walter J. Urba, M.D., Ph.D. and Dan L. Longo, M.D. raise several important consideration in regard to the genetically-modified, serial killer T-cell therapy discussed above.

First, the editorial authors note that chimeric antigen receptors (or CARS) have theoretical advantages over other T-cell–based therapies, including: (i) use of the patient’s own cells, which avoids the risk of graft-versus-host disease; (ii) the ability to create CARs quickly; and (iii) use of the same CAR for multiple patients.

While noting the remarkable clinical outcome of the 64-year old male CLL patient described above, the editorial authors note that in addition to tumor lysis syndrome, the patient experienced B-cell depletion and hypogammaglobulinemia. Although these conditions may not create a major problem in patients with CLL, the authors state that the persistence of activated T-cells, memory T-cells, or both could pose substantial problems in other tumor types.

According to the editorial authors, both toxic effects to the target organ and also “on-target, but off-organ” toxic effects have been observed by other researchers in the past because of unanticipated cross-reactive target antigens.

While toxicity may become more of a problem as more potent second- and third-generation CARs are used in patients with different tumor types, the authors explain that additional safety measure may help offset that risk. The safety measures highlighted in the editorial include: (i) the infusion of a lower number of T-cells, (ii) the use of immunosuppressive agents, and (iii) the introduction of an inducible “suicide signal” to kill the cells when they are creating mischief.

In connection with the third safety measured provided above, the authors state that a novel, non-immunogenic, inducible caspase 9suicide gene” has already been developed. Nevertheless, the authors warn that the suicide gene strategy may not have time to work properly because the deaths from toxic effects reported in the past have been severe and occurred within hours after administration of the gene-transfected cells.

The editorial authors conclude that only with the more widespread clinical use of CAR T-cells will researchers learn whether the results reported by Porter et al. represent a true advancement toward a clinically applicable and effective therapy, or alternatively, another promising strategy that runs into an insurmountable barrier which is difficult to overcome.

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.

About the University of Pennsylvania Perelman School of Medicine

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 the 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.

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 our community.

Sources:

  • Urba WJ & Longo DL. Redirecting T CellsN Engl J Med Editorial. Published online August 10, 2011 (10.1056/NEJMe1106965).

2011 ASCO: Women with BRCA Gene Mutations Can Take Hormone-Replacement Therapy Safely After Ovary Removal

Women with the BRCA1 or BRCA2 gene mutations, which are linked to a very high risk of breast and ovarian cancer, can safely take hormone-replacement therapy (HRT) to mitigate menopausal symptoms after surgical removal of their ovaries, according to new research from the Perelman School of Medicine at the University of Pennsylvania

Women with the BRCA1 or BRCA2 gene mutations, which are linked to a very high risk of breast and ovarian cancer, can safely take hormone-replacement therapy (HRT) to mitigate menopausal symptoms after surgical removal of their ovaries, according to new research from the Perelman School of Medicine at the University of Pennsylvania which will be presented on Monday, June 6 during the American Society for Clinical Oncology’s annual meeting. Results of the prospective study indicated that women with BRCA mutations who had their ovaries removed and took short-term HRT had a decrease in the risk of developing breast cancer.

Research has shown that in women who carry the BRCA gene mutations, the single most powerful risk-reduction strategy is to have their ovaries surgically removed by their mid-30s or early 40s. The decrease in cancer risk from ovary removal comes at the cost of early menopause and menopausal symptoms including hot flashes, mood swings, sleep disturbances and vaginal dryness — quality-of-life issues that may cause some women to delay or avoid the procedure.

Lead study author Susan M. Domchek, M.D., Associate Professor, Divison of Hematology-Oncology & Director, Cancer Risk Evaluation Program, Abramson Cancer Center, University of Pennsylvania

“Women with BRCA1/2 mutations should have their ovaries removed following child-bearing because this is the single best intervention to improve survival,” says lead author Susan M. Domchek, M.D., an associate professor in the division of Hematology-Oncology and director of the Cancer Risk Evaluation Program at Penn’s Abramson Cancer Center. “It is unfortunate to have women choose not to have this surgery because they are worried about menopausal symptoms and are told they can’t take HRT. Our data say that is not the case — these drugs do not increase their risk of breast cancer.”

Senior author Timothy R. Rebbeck, Ph.D., associate director of population science at the Abramson Cancer Center, notes that BRCA carriers may worry — based on other studies conducted in the general population showing a link between HRT and elevated cancer risk — that taking HRT may negate the effects of the surgery on their breast cancer risk. The message he hopes doctors will now give to women is clear: “If you need it, you can take short-term HRT. It doesn’t erase the effects of the oophorectomy.”

In the current study, Domchek, Rebbeck, and colleagues followed 795 women with BRCA1 mutations and 504 women with BRCA2 mutations who have not had cancer enrolled in the PROSE consortium database who underwent prophylactic oophorectomy, divided into groups of those who took HRT and those who did not. Women who underwent prophylactic oophorectomy had a lower risk of breast cancer than those who did not, with 14 percent of the women who took HRT after surgery developing breast cancer compared to 12 percent of the women who did not take HRT after surgery. The difference was not statistically significant.

Domchek says some of the confusion about the role of HRT in cancer risk elevation comes from the fact that the risks and benefits associated with HRT depend on the population of women studied. In this group of women — who have BRCA1/2 mutations and who have had their ovaries removed while they are quite young — HRT should be discussed and considered an option for treating menopausal symptoms. “People want to make hormone replacement therapy evil, so they can say ‘Don’t do it,'” she says. “But there isn’t one simple answer. The devil is in the details of the studies.”

By contrast, Penn researchers and their collaborators in the PROSE consortium have shown definitively that oophorectomy reduces ovarian and breast cancer incidence in these women, and reduces their mortality due to those cancers. But paying attention to the role that hormone depletion following preventive oophorectomy plays in women’s future health is also important.

“We know for sure that using HRT will mitigate menopausal symptoms, and we have pretty good evidence that it will help bone health,” she says. “Women need to be aware that going into very early menopause does increase their risk of bone problems and cardiovascular problems. And even if they aren’t going to take HRT, they need to be very attentive to monitoring for those issues. But they also need to know that HRT is an option for them and to discuss it with their doctors and other caregivers.”

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 our community.

About the University of Pennsylvania Perelman School of Medicine

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 the 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.

Sources: