On December 4, 2018 City of Hope physicians and researchers reported at the American Society of Hematology (ASH) (Free ASH Whitepaper) meeting in San Diego presented clinical trials for new leukemia and lymphoma treatments, laying the groundwork for innovative therapeutic approaches aimed at improving treatment options and quality of life for patients (Press release, City of Hope, DEC 4, 2018, View Source [SID1234531885]).
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The ASH (Free ASH Whitepaper) meeting hosted more than 25,000 hematology professionals who focus on research and treatment for blood cancers and other diseases.
"City of Hope clinical and laboratory investigators enjoyed sharing our leading-edge research findings and demonstrating our continued commitment to advancing the most promising cures against cancers, including finding new targets in CAR T cell therapy," said Stephen J. Forman, M.D., leader of City of Hope’s Hematologic Malignancies and Stem Cell Transplantation Institute and the Francis & Kathleen McNamara Distinguished Chair in Hematology and Hematopoietic Cell Transplantation.
City of Hope physician-scientists presented clinical trials that provide the foundation for new treatments for patients with T cell lymphoma, non-Hodgkin’s lymphoma and acute lymphoblastic leukemia. They also discussed mouse studies that experimented with a different and possibly more effective way of delivering chimeric antigen receptor (CAR) T cells for leukemia and lymphoma in the central nervous system (CNS). The research is discussed in more detail below.
Delivering CD19-CAR T cells directly into cerebrospinal fluid to treat a lymphoma
This study is touted as the first to demonstrate that local brain delivery of CAR T cells are capable of treating both systemic lymphoma and the CNS. Xiuli Wang, Ph.D., research professor in the Department of Hematology & Hematopoietic Cell Transplantation at City of Hope, said immunotherapy that uses T cells genetically modified with the CD19-CAR lentivirus have been effective in treating acute lymphoblastic leukemia and diffuse large B cell lymphoma. Notably, CNS lymphoma, a disease limited to brain, cannot be treated through surgery because the tumors are widespread, and chemo-drugs cannot pass through the protective blood-brain barrier. CAR T cell therapies are usually delivered intravenously and have not been used in treatment for CNS lymphoma due to concerns of effectiveness and potential side effects such as cytokine release syndrome.
People with CNS lymphoma have limited options; City of Hope wants to expand their options. Using a mouse model, Wang and her colleagues delivered T cells modified to express a CD19-CAR directly into cerebro-spinal fluid via cerebral ventricles, a process called intracerebroventricular infusion. A single local infusion was enough to completely eradicate CNS lymphoma and systemic lymphoma throughout the mouse body after 14 days. The mice remained tumor-free for 300 days, the length of the experiment. Comparatively, the mice who received the immunotherapy treatment intravenously had delayed anti-tumor activity: Complete remission was observed about 40 days post CAR T treatment. Eventually the tumors relapsed, and all of the control mice died before day 180.
The experiment demonstrated that delivering CAR T locally into the cerebro-spinal fluid appears to be more efficacious than intravenous delivery. When researchers imaged the mice, they found that CAR T cells migrated to the tumor sites outside the brain. So, local brain delivery of this immunotherapy was able to spread throughout their body. Lastly, the CAR T cells persisted in the mice with the experimental treatment much longer than when they are delivered intravenously – helping to maintain an anti-tumor environment to ward off relapse.
Wang hypothesizes that intracerebroventricular infusion of CAR T therapy may be safer and more effective than intravenous infusion. Her team will test this hypothesis in a phase 1 clinical trial next year.
A chemotherapy-free immunotherapy that uses a special two-armed antibody
In a multisite, international phase 1/1b clinical trial, Lihua Elizabeth Budde, M.D., Ph.D., assistant professor in the Department of Hematology & Hematopoietic Cell Transplantation at City of Hope, et al. are testing a promising two-armed antibody that could strong-arm relapsed/refractory B cell non-Hodgkin’s lymphoma into remission. (Normal antibodies have only one arm.) If proven effective, the treatment heralds a new age where chemotherapy and its painful side effects will be obsolete in the treatment of this disease.
The ongoing first-in-human study testing for safety has recruited more than 98 patients to receive varying doses of mosunetuzumab, an experimental antibody with two arms. One arm grabs specific immune cells in the body while the other grabs lymphoma cells. Now in close proximity, the immune cells are trained or forced to recognize and attack lymphoma cells.
Unlike CAR T therapy, this treatment option does not involve removing a patient’s immune cells, modifying them to attack disease and expanding the T cells outside the body. Mosunetuzumab is delivered intravenously and redirects T cells to recognize the cancer; everything happens inside the human body.
The trial’s response rate is around 70 percent, which is promising because the maximum tolerated dose has not yet been reached. So far, most patients who experienced adverse effects had minor, manageable and reversible side effects, Budde said. Most of the patients are in complete remission and have stayed in remission – the longest patient has been cancer-free for more than two years –without needing any other treatment, she added.
Novel regimen for patients with certain lymphomas undergoing a stem cell transplant
In a phase 1 clinical trial designed to test the safety and tolerability of a novel conditioning regimen for patients with peripheral T cell lymphomas undergoing autologous stem cell transplants (which use the patient’s own stem cells), Jasmine Zain, M.D., director of City of Hope’s T cell Lymphoma Program, and her colleagues found that City of Hope-manufactured 90Yttrium-radiolabeled (90Y) basiliximab appears to be safe when used in combination with BEAM. There was no increased toxicity compared to using BEAM chemotherapy alone, and side effects were minimal, the study found.
Peripheral T cell lymphomas have a poor prognosis with current treatment regimens. In spite of autologous stem cell transplants, patients often relapse within a few years. The protein CD25 is differentially expressed in T cell lymphomas. Basliximab is an antibody that targets CD25. 90Y basiliximab provides targeted radiation to tumor cells and has been shown to successfully inhibit the growth of T cell lymphomas in mouse models.
In this phase 1 study, three different dose levels of targeted radiation were explored in combination with chemotherapy with BEAM. Fourteen patients underwent the experimental treatment over a nearly three-year period with no additional toxicity. Eight patients remain in remission. A safe dose level has been established. The study was not designed to assess efficacy of the regimen, but a dose expansion phase is in progress to answer that question.
Memory-enriched CAR T cells: High response rates and low toxicity
CAR T cell therapy reportedly achieves complete remission in patients with acute lymphoblastic leukemia about 80 percent of the time; however, a large proportion of these patients have side effects such as cytokine release syndrome and neurotoxicity. Samer Khaled, M.D., associate clinical professor in the Department of Hematology & Hematopoietic Cell Transplantation at City of Hope, said he may have found a CAR T product that is more potent and less toxic – a potential game-changer if the early results of his ongoing phase 1 clinical trial holds through future testing.
So far, the clinical trial has enrolled 16 patients with relapsed or refractory B cell acute lymphoblastic leukemia, a disease that has poor survival rates. The physician-scientists treated 13 eligible patients with T cells engineered to express CD19:28z-CAR. Investigators used a unique manufacturing platform developed at City of Hope that generates therapeutic cells from enriched memory and "naïve T cells" – immune soldiers known for their capacity for long-term persistence.
Eleven out of 11 patients evaluable for response received the treatment and are in complete remission, showing a 100 percent response rate with no significant increase in toxicity. Two patients were not eligible for response evaluation but were included in the toxicity assessment. Though the sample size was small, it is noteworthy. "Traditionally, high CAR T activity is associated with high toxicity, but our CD19 CAR T product appears to be a very powerful therapy with lower-than-normal side effects," Khaled said.
City of Hope research on a new CAR T therapy, BAFF-R
Hong Qin, Ph.D., associate research professor in City of Hope’s Department of Hematology & Hematopoietic Cell Transplantation, and Larry Kwak, M.D., Ph.D., Dr. Michael Friedman Professor in Translational Medicine and director of the Toni Stephenson Lymphoma Center, have conducted new research demonstrating that a CAR T cell therapy targeting the B-cell activating factor receptor (BAFF-R), a protein which is primarily expressed on B-cells and various subtypes of B-cell non-Hodgkin’s lymphoma (NHL) and acute lymphoblastic leukemia (ALL), can be used to help patients who are experiencing relapse after receiving other CAR T therapies.
CAR T therapies targeting CD19, another target on B-cell tumors, is becoming more common, but so are cases of CD19 antigen-loss relapse. The increase of relapse highlights an urgent need for new therapies and tumor targets.
City of Hope research has led to the development of a highly effective BAFF-R targeting CAR T cells that works against a variety of human B-cell leukemia and lymphoma models. Encouragingly, BAFF-R CAR T cells remain effective against tumor samples from ALL patients who experienced CD19 antigen-loss relapse. The new data suggest that targeting BAFF-R may add to existing alternative strategies to overcome relapse from CD19 antigen loss.
"City of Hope is planning a clinical trial in the coming year that will be the first BAFF-R CAR T trial for patients, providing new hope for patients who have no other therapeutic options," Qin said.