CRISPR Therapeutics and Vertex Announce Positive Safety and Efficacy Data From First Two Patients Treated With Investigational CRISPR/Cas9 Gene-Editing Therapy CTX001® for Severe Hemoglobinopathies

-Two patients treated with CTX001 successfully engrafted and demonstrated an initial safety profile consistent with myeloablative busulfan conditioning and autologous hematopoietic stem cell transplant-

-Beta thalassemia: Patient is transfusion independent with total hemoglobin level of 11.9 g/dL and 10.1 g/dL fetal hemoglobin at nine months after CTX001 infusion-

-Sickle cell disease: Patient is free of vaso-occlusive crises with total hemoglobin level of 11.3 g/dL and 46.6% fetal hemoglobin at four months after CTX001 infusion-

ZUG, Switzerland and CAMBRIDGE, MA and BOSTON, MA, USA I November 19, 2019 I CRISPR Therapeutics (NASDAQ: CRSP) and Vertex Pharmaceuticals Incorporated (NASDAQ: VRTX) today announced positive, interim data from the first two patients with severe hemoglobinopathies treated with the investigational CRISPR/Cas9 gene-editing therapy CTX001 in ongoing Phase 1/2 clinical trials. One patient with transfusion-dependent beta thalassemia (TDT) received CTX001 in the first quarter of 2019 and data for this patient reflect nine months of safety and efficacy follow-up. One patient with severe sickle cell disease (SCD) received CTX001 in mid-2019 and data for this patient reflect four months of safety and efficacy follow-up. These studies are ongoing and patients will be followed for approximately two years following infusion. Several additional patients have been enrolled and have had drug product manufactured across the two studies.

Transfusion-Dependent Beta Thalassemia
The patient with TDT has the β0/IVS-I-110 genotype and required 16.5 transfusions per year (annualized rate during the two years prior to consenting for the study) before enrolling in the clinical study. The patient achieved neutrophil engraftment 33 days after CTX001 infusion and platelet engraftment 37 days after infusion. Two serious adverse events (SAEs) occurred, neither of which the principal investigator (PI) considered related to CTX001: pneumonia in the presence of neutropenia and veno-occlusive liver disease attributed to busulfan conditioning; both subsequently resolved. At nine months after CTX001 infusion, the patient was transfusion independent and had total hemoglobin levels of 11.9 g/dL, 10.1 g/dL fetal hemoglobin, and 99.8% F-cells (erythrocytes expressing fetal hemoglobin).

Sickle Cell Disease
The patient with SCD experienced seven vaso-occlusive crises (VOCs) per year (annualized rate during the two years prior to consenting for the study) before enrolling in the clinical study. The patient achieved neutrophil and platelet engraftment 30 days after CTX001 infusion. Three SAEs occurred, none of which the PI considered related to CTX001: sepsis in the presence of neutropenia, cholelithiasis, and abdominal pain, all of which resolved. At four months after CTX001 infusion, the patient was free of VOCs and had total hemoglobin levels of 11.3 g/dL, 46.6% fetal hemoglobin, and 94.7% F-cells (erythrocytes expressing fetal hemoglobin).

“We are very encouraged by these preliminary data, the first such data to be reported for patients with beta thalassemia and sickle cell disease treated with our CRISPR/Cas9 edited autologous hematopoietic stem cell candidate, CTX001,” said Samarth Kulkarni, Ph.D., Chief Executive Officer of CRISPR Therapeutics. “These data support our belief in the potential of our therapies to have meaningful benefit for patients following a one-time intervention. We continue to enroll these studies as we drive forward to develop CRISPR/Cas9 therapies as a new class of transformative medicines to treat serious diseases.”

“The data we announced today are remarkable and demonstrate that CTX001 has the potential to be a curative CRISPR/Cas9-based gene-editing therapy for people with sickle cell disease and beta thalassemia,” said Jeffrey Leiden, M.D., Ph.D., Chairman, President and Chief Executive Officer of Vertex. “While the data are exciting, we are still in the early phase of this clinical program. We look forward to continuing to work with physicians, patients, caregivers and families over the coming months and years to bring forward the best possible therapy for these two serious diseases and to continue to accelerate our gene-editing programs for other serious diseases such as Duchenne muscular dystrophy and myotonic dystrophy type 1.”

About the Phase 1/2 Study in Transfusion-Dependent Beta Thalassemia
The ongoing Phase 1/2 open-label trial, CLIMB-Thal-111, is designed to assess the safety and efficacy of a single dose of CTX001 in patients ages 18 to 35 with TDT. The study will enroll up to 45 patients and follow patients for approximately two years after infusion. Each patient will be asked to participate in a long-term follow-up study. Enrollment is ongoing at six clinical trial sites in the United States, Canada and Europe.

About the Phase 1/2 Study in Sickle Cell Disease
The ongoing Phase 1/2 open-label trial, CLIMB-SCD-121, is designed to assess the safety and efficacy of a single dose of CTX001 in patients ages 18 to 35 with severe SCD. The study will enroll up to 45 patients and follow patients for approximately two years after infusion. Each patient will be asked to participate in a long-term follow-up study. Enrollment is ongoing at 12 clinical trial sites in the United States, Canada and Europe.

About the Gene-Editing Process in These Trials
Patients who enroll in these studies will have hematopoietic stem and progenitor cells collected from peripheral blood. The patient’s cells will be edited using the CRISPR/Cas9 technology. The edited cells, CTX001, will then be infused back into the patient as part of a stem cell transplant, a process which involves, among other things, a patient being treated with myeloablative busulfan conditioning. Patients undergoing stem cell transplants may also encounter side effects (ranging from mild to severe) that are unrelated to the administration of CTX001. Patients will initially be monitored to determine when the edited cells begin to produce mature blood cells, a process known as engraftment. After engraftment, patients will continue to be monitored to track the impact of CTX001 on multiple measures of disease.

CRISPR Therapeutics Conference Call and Webcast
CRISPR Therapeutics will host a conference call and webcast today at 8:00 a.m. ET. The webcast and presentation will be made available on the CRISPR Therapeutics website at in the Investors section under Events and Presentations. Following the live audio webcast, a replay will be available on the Company's website for approximately 30 days.

About CTX001
CTX001 is an investigational ex vivo CRISPR gene-edited therapy that is being evaluated for patients suffering from TDT or severe SCD in which a patient’s hematopoietic stem cells are engineered to produce high levels of fetal hemoglobin (HbF; hemoglobin F) in red blood cells. HbF is a form of the oxygen-carrying hemoglobin that is naturally present at birth and is then replaced by the adult form of hemoglobin. The elevation of HbF by CTX001 has the potential to alleviate transfusion requirements for TDT patients and painful and debilitating sickle crises for SCD patients.

CTX001 is being developed under a co-development and co-commercialization agreement between CRISPR Therapeutics and Vertex.

About the CRISPR-Vertex Collaboration
CRISPR Therapeutics and Vertex entered into a strategic research collaboration in 2015 focused on the use of CRISPR/Cas9 to discover and develop potential new treatments aimed at the underlying genetic causes of human disease. CTX001 represents the first treatment to emerge from the joint research program. CRISPR Therapeutics and Vertex will jointly develop and commercialize CTX001 and equally share all research and development costs and profits worldwide.

About CRISPR Therapeutics
CRISPR Therapeutics is a leading gene editing company focused on developing transformative gene-based medicines for serious diseases using its proprietary CRISPR/Cas9 platform. CRISPR/Cas9 is a revolutionary gene editing technology that allows for precise, directed changes to genomic DNA. CRISPR Therapeutics has established a portfolio of therapeutic programs across a broad range of disease areas including hemoglobinopathies, oncology, regenerative medicine and rare diseases. To accelerate and expand its efforts, CRISPR Therapeutics has established strategic collaborations with leading companies including Bayer AG, Vertex Pharmaceuticals and ViaCyte, Inc. CRISPR Therapeutics AG is headquartered in Zug, Switzerland, with its wholly-owned U.S. subsidiary, CRISPR Therapeutics, Inc., and R&D operations based in Cambridge, Massachusetts, and business offices in London, United Kingdom. For more information, please visit

About Vertex
Vertex is a global biotechnology company that invests in scientific innovation to create transformative medicines for people with serious diseases. The company has four approved medicines that treat the underlying cause of cystic fibrosis (CF) — a rare, life-threatening genetic disease — and has several ongoing clinical and research programs in CF. Beyond CF, Vertex has a robust pipeline of investigational small molecule medicines in other serious diseases where it has deep insight into causal human biology, including pain, alpha-1 antitrypsin deficiency, and APOL1-mediated kidney disease. In addition, Vertex has a rapidly expanding pipeline of genetic and cell therapies for diseases such as sickle cell disease, beta thalassemia, Duchenne muscular dystrophy and type 1 diabetes mellitus.

Founded in 1989 in Cambridge, Mass., Vertex's global headquarters is now located in Boston's Innovation District and its international headquarters is in London, UK. Additionally, the company has research and development sites and commercial offices in North America, Europe, Australia and Latin America. Vertex is consistently recognized as one of the industry's top places to work, including 10 consecutive years on Science magazine's Top Employers list and top five on the 2019 Best Employers for Diversity list by Forbes. For company updates and to learn more about Vertex's history of innovation, visit or follow us on Facebook, Twitter, LinkedIn, YouTube and Instagram.

SOURCE: Vertex Pharmaceuticals

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