Update: Statement on NHLBI decision to resume participant enrollment in the Pilot and Feasibility Study of Hematopoietic Stem Cell Gene Transfer for Sickle Cell Disease
December 27, 2021
On Feb. 17, 2021, out of an abundance of caution and concern for patient safety, the National Heart, Lung, and Blood Institute (NHLBI), part of NIH, placed an administrative hold on an NHLBI-funded trial at the Boston Children’s Hospital, the Pilot and Feasibility Study of Hematopoietic Stem Cell Gene Transfer for Sickle Cell Disease. Following a review of the recommendation of the NHLBI Gene and Cell Therapy Data and Safety Monitoring Board (DSMB), which was informed by a thorough examination of safety information and extensive expert consultations, NHLBI lifted the study’s administrative hold and resumed enrollment on Dec. 1, 2021.
During the period the trial was on hold, NHLBI took several important steps to further ensure the safety of research participants and the scientific integrity of the research. Specifically, NHLBI performed a comprehensive assessment of available safety information, including convening, and soliciting input from multidisciplinary scientific and clinical perspectives, as well as patient perspectives. The assessment involved:
- reviewing safety data and analyses from the bluebird bio, Inc. trial, which was suspended on Feb. 16, 2021, due to questions (later resolved) about myeloid neoplasms following gene therapy of two of their research participants;
- convening a special panel of hematology-oncology specialists, scientific experts in a wide range of relevant fields; and
- engaging in consultations with key scientific and patient groups.
The insights gained through these deliberations enabled the investigators to supplement their existing plans to further minimize risks to research participants (Risk Mitigation Plan). This plan has since been reviewed by the DSMB and the U.S. Food and Drug Administration (FDA) and was implemented for screening potential participants and following up participants already enrolled.
The Risk Mitigation Plan was reviewed carefully by an independent panel of cancer genomics experts. These experts provided their findings to the study’s DSMB on Sept. 10, 2021, for review. Following its review of this panel’s report and other data, the DSMB recommended lifting the administrative hold placed on the trial. The NHLBI accepted the recommendation. Currently, investigators are taking the following actions:
- engaging actively in the development of a risk mitigation plan for use in clinical trials across the Cure Sickle Cell Initiative;
- continuing to conduct vector integration site analysis as a standard element of surveillance testing in all participants following product administration;
- committing to sharing data in keeping with the policies and practices of the Cure Sickle Cell Initiative to help inform the field at large; and
- ensuring continued and clear communication to trial participants about the return of research results, which should incorporate independent genetic counseling to facilitate the participants’ understanding of research results.
NHLBI remains committed in its pursuit of a cure for sickle cell disease. We will continue communicate any updates as necessary.
Statement on NHLBI decision to pause the Pilot and Feasibility Study of Hematopoietic Stem Cell Gene Transfer for Sickle Cell Disease
February 22, 2021
On Feb. 16, 2021, bluebird bio, Inc. suspended its clinical trial exploring the curative potential of genetic therapy for sickle cell disease using its lentiviral vector (gene therapy delivery system), because two research participants in this trial developed myeloid neoplasms following gene therapy. Out of an abundance of caution, on Feb. 17, 2021, the National Heart, Lung, and Blood Institute (NHLBI), part of the NIH, paused participant enrollment and gene transfers in an NHLBI-funded trial at the Boston Children’s Hospital, Pilot and Feasibility Study of Hematopoietic Stem Cell Gene Transfer for Sickle Cell Disease. Since this trial began in February 2018, nine individuals with sickle cell disease have been treated. The Boston Children’s trial uses a different, yet related, vector, and targets a different gene than those used in the bluebird bio, Inc. trial. However, despite having no indications of such harm in the Boston Children’s trial, NHLBI is taking this action following the announcement that bluebird bio, Inc. temporarily suspended its study.
For more than a decade, gene therapy has been considered a promising approach to a cure for sickle cell disease. Lentiviral vectors have been a critical part of the process, as they are used to deliver a therapeutic gene into blood producing stem cells in the bone marrow. This therapy results in the production of healthy (or normal) hemoglobin in red blood cells.
The Institute has requested that its Data and Safety Monitoring Board (DSMB) conduct an independent safety review of the NHLBI-funded Boston Children’s Hospital. Patient volunteers and their safety are the highest priority in any research endeavor, and their participation is the foundation for scientific progress. NHLBI recognizes and honors the important contributions of these and all clinical research volunteers in advancing science toward a cure for this disease.
NHLBI remains committed in its pursuit of a cure for sickle cell disease. The Institute will reassess this pause following a thorough review of the Boston Children’s Hospital study by the DSMB and input from the U.S. Food and Drug Administration, which provides regulatory oversight of all gene therapy in the United States.