Cambridge, Mass. – December 6, 2020 – HighPassBio, an ElevateBio portfolio company dedicated to advancing novel targeted T cell immunotherapies, today discussed the ongoing Phase 1 trial of the company’s lead product candidate, an engineered T cell receptor (TCR) T cell therapy targeting HA-1 expressing cancer cells in an oral presentation at the 62nd American Society of Hematology (ASH) Annual Meeting. The Phase 1 clinical trial, which is being conducted by researchers at Fred Hutchinson Cancer Research Center, is designed to assess the feasibility, safety, and efficacy of this novel cell therapy in the treatment of leukemia following hematopoietic stem cell transplant (HSCT).
“The prognosis for leukemia patients who’ve relapsed or who have residual disease following allogeneic hematopoietic stem cell transplantation is often poor, but we believe that by targeting the minor H antigen, HA-1, through a novel T cell immunotherapy, we can potentially treat and prevent subsequent relapse,” said Elizabeth Krakow, M.D., MSc., Assistant Professor, Clinical Research Division, Fred Hutchinson Cancer Research Center, principal investigator of the study, and presenting author. “We have observed early promising indicators of anti-leukemic activity following treatment in this trial. We are eager to expand the trial to additional patients as we continue to research the feasibility, safety, and efficacy of this approach.”
The abstract for the presentation titled Phase 1 Study of Adoptive Immunotherapy with HA-1-Specific CD8+ and CD4+ Memory T Cells for Children and Adults with Relapsed Acute Leukemia after Allogeneic Hematopoietic Stem Cell Transplantation (HCT): Trial in Progress, can be found on the ASH website under the abstract number 137726.
To date, four patients, including one pediatric patient, have received a total of six infusions in the Phase 1 clinical trial. Patient characteristic data was shared in the oral presentation at ASH, including documented HA-1 TCR T cell persistence in blood and bone marrow up to 18 months. In some patients, clear in vivo anti-leukemic activity was observed at the first dose level, including a subject with aggressive, highly refractory T-ALL and early post-HCT relapse. No significant toxicities attributed to the T cells have been observed, including no infusion reactions or evidence of cytokine release syndrome or graft versus host disease.
The Phase 1 clinical trial is currently recruiting adult and pediatric patients who have residual disease or relapsed leukemia or related conditions following HSCT. As part of the trial, transplant patients and prospective donors may be recruited to participate in the genetic screening portion to determine eligibility. More details are available on clinicaltrials.gov under the study ID number NCT03326921.
About TCR-Engineered T Cell Therapy
A key role of the immune system is to detect tumor antigens, engage T cells, and eradicate the tumor. However, the immune response to tumor antigens varies and is often insufficient to prevent tumor growth and relapse. An approach known as adoptive T cell therapy, using T cell receptors, or TCRs, can overcome some of the obstacles to establishing an effective immune response to fight off the target tumor. TCRs are molecules found on surface of T cells that can recognize tumor antigens that are degraded to small protein fragments inside tumor cells. Unlike CAR T cells that recognize only surface antigens, TCRs can recognize small protein fragments derived from intracellular and surface antigens offering a more diverse way to attack tumors. These small protein fragments show up on the tumor cell surface, with another protein called major histocompatibility complex (MHC), that are recognized by the TCRs and consequently signal the body’s immune system to respond to fight off and kill the tumor cells.
Tumor-specific TCRs can be identified and then engineered into T cells that recognize and attack various types of cancers, representing a novel approach to treating and potentially preventing disease.
Adoptive T cell therapy can be applied to tackling relapse of leukemia post hematopoietic stem cell transplant (HSCT) by targeting the antigens expressed only by the patient’s native cells, and not by the cells from the stem cell transplant donor. HA-1, a known minor histocompatibility antigen, is expressed predominantly or exclusively on hematopoietic cells, including leukemic cells. There is evidence that T cells specific for HA-1 can induce a potent and selective antileukemic effect. HA-1 TCR T cell therapy is a new investigational immunotherapy for the management of post transplantation leukemia relapse.
About Leukemia post HSCT Treatment and the Risk of Relapse
Leukemia, a cancer of the blood or bone marrow characterized by an abnormal proliferation of blood cells, is the tenth most common type of cancer in the U.S. with an estimated 60,140 new cases and 24,400 deaths in 2016. Leukemia arises from uncontrolled proliferation of a specific type of hematopoietic (blood) cell that is critical for a functional immune system. As a result, when patients are given very high doses of chemotherapy to eradicate leukemic cells, most normal cells are killed as well, necessitating a transplant of hematopoietic stem cells from a donor to reconstitute the patient’s bone marrow and circulating hematopoietic cells. In some cases, the transplanted T cells from the donor can also recognize and eliminate the hematopoietic cells, including leukemia, from the recipient, thus preventing relapse. This can be described as a graft versus leukemia effect. Other hematologic disorders related to leukemia, like myelodysplastic syndrome (MDS), can also be treated in this way.
While HSCT can be curative, it is estimated that 25-50 percent of HSCT recipients relapse; leukemia relapse remains the major cause of allogeneic HSCT failure, and the prognosis for patients with post-HCT relapse is poor. Relapse occurs following allogeneic HSCT in approximately one-third of patients with acute leukemia who undergo the procedure, and most patients subsequently die of their disease.
HighPassBio, an ElevateBio portfolio company, is working to advance a novel approach to treating hematological malignancies by leveraging T cell receptor (TCR)-engineered T cells, known as TCR T cells. The company’s lead program is designed to treat or potentially prevent relapse of leukemia in patients who have undergone hematopoietic stem cell transplant (HSCT). The technology was born out of research conducted at Fred Hutchinson Cancer Research Center by world renowned expert, Dr. Marie Bleakley.
ElevateBio, LLC, is a Cambridge-based creator and operator of a portfolio of innovative cell and gene therapy companies. It begins with an environment where scientific inventors can transform their visions for cell and gene therapies into reality for patients with devastating and life-threatening diseases. Working with leading academic researchers, medical centers, and corporate partners, ElevateBio’s team of scientists, drug developers, and company builders are creating a portfolio of therapeutics companies that are changing the face of cell and gene therapy and regenerative medicine. Core to ElevateBio’s vision is BaseCamp, a centralized state-of-the-art innovation and manufacturing center, providing fully integrated capabilities, including basic and translational research, process development, clinical development, cGMP manufacturing, and regulatory affairs across multiple cell and gene therapy and regenerative medicine technology platforms. ElevateBio portfolio companies, as well as select strategic partners, are supported by ElevateBio BaseCamp in the advancement of novel cell and gene therapies.
ElevateBio’s investors include F2 Ventures, MPM Capital, EcoR1 Capital, Redmile Group, Samsara BioCapital, The Invus Group, Surveyor Capital (A Citadel company), EDBI, and Vertex Ventures.
ElevateBio is headquartered in Cambridge, Mass, with ElevateBio BaseCamp located in Waltham, Mass. For more information, please visit www.elevate.bio.
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