Rob Schott
Analyst · Nicole Germino from Truist Securities
Thank you, Sandy, and good afternoon to everyone on the call. Our development organization remains focused on execution in the clinic, and we are pleased with this quarter's progress. Beginning with our Phase I/II STAAR study examining isaralgagene civaparvovec, or ST-920, which is our wholly owned gene therapy program for the treatment of Fabry Disease in adults. This quarter, the Safety Monitoring Committee approved escalating to a fourth dose cohort as outlined in the STAAR study protocol. This was based on the totality of data from the previously dosed patients. 2 patients have since been dosed in cohort 4 at the 5e13 vector genomes per kilogram dose level, completing the dose escalation portion of the Phase I/II study. Furthermore, this quarter, we dosed an additional patient in cohort 3. This achieves a total of 3 patients in this cohort in 9 patients overall that have been dosed in the STAAR study to date. In addition, during this quarter, we completed withdrawal of enzyme replacement therapy from a second patient, which means that we now have withdrawn on each from the first and second cohorts. These patients are being closely monitored and investigators have thus far not deemed it necessary to resume enzyme replacement therapy. We expect to provide updated results from the STAAR study in the second half of 2022 and are actively preparing for both the Phase I/II expansion cohorts in a Phase III clinical trial. In the Phase I/II PRECIZN-1 study of SAR445136 for the treatment of sickle cell disease. This quarter, we dosed the fifth patient. This patient was the first in the study to receive a product candidate manufactured using improved methods that have been shown in internal experiments to increase the number of long-term progenitor cells in the final product. We expect to dose the remaining patients in the study in the third quarter of this year. We look forward to sharing an update on the PRECIZN-1 study in the second half of 2022. Feedback has been received from the FDA and Phase III enabling activities, including manufacturing readiness are in progress. The orderly transition of Sanofi's rights and obligations under this program back to Sangamo is progressing well and is on track to be completed on June 28. As previously outlined, Sangamo is excited to have this asset back in our hands soon. As Sandy outlined in his opening, Pfizer recently announced that in March of this year, the FDA lifted its clinical hold on the Phase III AFFINE trial, evaluating giroctocogene fitelparvovec, an investigational gene therapy for hemophilia A. The hold was put in place following the observance of Factor VIII expression levels greater than 150% in some treated participants. Pfizer has announced that the voluntary pause remains in place until all necessary conditions are met, including approval of an updated drought protocols by regulatory authorities. In addition, Pfizer was made aware of a below-the-knee deep veins thrombosis in 1 participant with elevated Factor VIII levels. This patient had a history of thrombotic events prior to participation in the trial, which is a known risk factor for subsequent events and an exclusion criterion for participation in the AFFINE trial. The case was assessed to understand all potential contributing factors, including mix doses of investigator prescribed direct oral anticoagulants. The patient is reported to be doing well. All study participants continue to be closely monitored and there have been no other thrombotic events reported in the study at this time. The information was shared with study investigators, health authorities and the independent external data monitoring committee and Pfizer responded to queries from health authorities. Pfizer and Sangamo remain committed to the hemophilia community and Pfizer anticipates resuming the trial in the third quarter of 2022 with a pivotal data readout estimated in the second half of 2023. In the first quarter, Sangamo also had significant and trailblazing development on our wholly owned TX200 CAR-Tregs cell therapy candidate for the prevention of immune-mediated rejection in HLA-A2 mismatch kidney transplantation from a living donor. On March 22, we dosed the first patient in our Phase I/II STEADFAST clinical study in what we believe is the first ever dosing of a human with a CAR-Tregs cell therapy candidate. Continuing Sangamo's track record of advancing groundbreaking therapies in genomic medicine. The patient continues to do well following dosing with the Autologous CAR-Tregs therapy and has not reported any adverse events related to the treatment to date. As you know, safety and tolerability continue to be among the major goals of the Phase I/II study. TX200 was designed with the potential to prevent kidney rejection by reducing local inflammation and promoting immunological tolerance to the graft. This investigational cell therapy is composed of Autologous CAR-Tregs cell engineered to express an HLA-A2, CAR and is being assessed in the HLA-A2-negative patients receiving a mismatched HLA-A2-positive kidney from a living donor. TX200 Engineer CAR-Tregs are expected to localize to the graft and activate upon binding the HLA-A2 antigen. Through their ability to regulate the immune system, TX200 cells may protect the graft for immune-mediated rejection and reduce or eliminate the need for lifelong treatment with immunosuppressants. In the STEADFAST clinical study design, each patient undergoes a leukapheresis procedure to collect their white blood cells, which after Tregs cells are isolated are genetically engineered and in cryopreserved. The patient subsequently undergoes transplantation surgery to receive a kidney from a living donor. Following a recovery period, the patient receives their individualized TX200 investigational cell therapy. Dosing of patients, therefore, occur several months after patient enrollment. Secondary objectives include the incidence of biopsy confirmed acute graft rejection, incidents of chronic graft rejection and confirmation that TX200 CAR-Tregs cells localized to the transplant of kidney. We also plan to evaluate the ability to reduce systemic immunosuppressive therapy, which carries the risk of significant systemic toxicity. Sangamo expects to dose a second patient in the STEADFAST study around the middle of 2022 based on their transplant schedule, and we plan to complete the first cohort, which comprises a total of 3 patients by the end of the year. We look forward to sharing data at the appropriate time. We see this study as the first step in our R&D journey towards a potential pipeline of CAR-Tregs therapies for autoimmune diseases. In addition to TX200, Sangamo is developing CAR-Tregs cell therapy candidates in preclinical studies, including for potential use in treating multiple sclerosis and inflammatory bowel disorders. I will now turn the call over to our Chief Scientific Officer, Jason Fontenot, for an update on our preclinical programs. Jason?