Fate Therapeutics Announces Day 100 Clinical Results from Phase 1 Stage of PROTECT Trial of ProTmune™ and Initiation of Phase 2 Stage

On December 11, 2017 Fate Therapeutics, Inc. (NASDAQ:FATE), a clinical-stage biopharmaceutical company dedicated to the development of programmed cellular immunotherapies for cancer and immune disorders, reported Day 100 clinical data from the Phase 1 stage of its PROTECT clinical trial of ProTmune, the Company’s next-generation hematopoietic cell graft for patients with hematologic malignancies (Press release, Fate Therapeutics, DEC 11, 2017, View Source [SID1234522554]). All seven subjects receiving ProTmune remained alive and relapse-free during the first 100 days following hematopoietic cell transplantation (HCT). Three of the seven subjects experienced acute graft-versus-host disease (GvHD) during the first 100 days following HCT. Each of these three subjects responded to standard-of-care steroid treatment with a median time to resolution of the maximum GvHD grade of 7 days [range: 5-8 days].

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"The significant risk of GvHD limits broad application of allogeneic transplant due to uncertainty of its short- and long-term impact on the recipient. It occurs frequently with variable intensity and can be a devastating disease when unresponsive to treatment. The requisite extended use of immunosuppressive agents to treat GvHD compromises the anti-leukemia activity of the transplant procedure and can significantly increase the risk of cancer relapse and mortality while also placing patients at risk for opportunistic infection," said Richard Maziarz, M.D., Principal Investigator, Oregon Health Sciences University. "The administration of a hematopoietic cell graft that is optimized to attenuate T-cell alloreactivity and maintain the graft’s anti-leukemia activity is a novel and highly-attractive therapeutic approach to decrease the risk and enhance the curative potential of allogeneic transplantation."

PROTECT Phase 1 Day 100 Clinical Results

Clinical data from the Phase 1 stage of PROTECT were presented today by Dr. Maziarz during a poster session at the 59th American Society of Hematology (ASH) (Free ASH Whitepaper) Annual Meeting and Exposition. The Phase 1 stage included seven adult subjects with hematologic malignancies undergoing matched unrelated donor HCT following myeloablative conditioning. During the first 100 days following HCT, all seven subjects receiving ProTmune remained alive and relapse-free. Three of the seven subjects experienced acute GvHD during the first 100 days following HCT, all of whom responded to standard-of-care steroid treatment. The median time to resolution of the maximum GvHD grade was 7 days [range: 5-8 days]. There were no events of graft failure, and there were no ProTmune-related serious adverse events reported by investigators.

PROTECT Day 100 Clinical Data
Subject 1 2 3 4 5 6 7
Hematologic Malignancy MDS AML AML ALL ALL ALL AML
CD34+ cell dose (x106/kg) 10.3 4.6 10.9 4.8 3.2 3.0 9.4
CD3+ cell dose (x108/kg) 3.1 1.8 2.6 2.8 2.0 1.2 2.8
ProTmune-related SAEs None None None None None None None
Day of Neutrophil Engraftment 1 Day 14 Day 18 Day 22 Day 15 Day 16 Day 18 Day 19
Acute GvHD / Grade (CIBMTR) None None Grade 2 None Grade 2 Grade 3 None
Treatment Responsive — — Yes — Yes Yes —
Time to Resolution of Maximum Grade — — 7 days — 8 days 5 days —
Cancer Relapse-free Yes Yes Yes Yes Yes Yes Yes
Survival Yes Yes Yes Yes Yes Yes Yes
1 As measured from the day following HCT

"The Day 100 clinical results from our Phase 1 stage of PROTECT support the unique therapeutic potential of ProTmune to reduce graft-versus-host disease and promote relapse-free survival. We are very encouraged by these initial clinical findings and the potential of ProTmune to deliver transformative benefits to cancer patients," said Chris Storgard, M.D., Chief Medical Officer of Fate Therapeutics. "The randomized, controlled and double-blinded Phase 2 stage of PROTECT is enrolling subjects at 14 U.S. centers of excellence. Given the high rates of morbidity and mortality underlying hematopoietic cell transplantation, we have also engaged the FDA, under our Fast Track designation for ProTmune, to discuss the necessary activities for product registration."

All subjects receiving ProTmune in the PROTECT Phase 1 stage are being followed for a period of two years following HCT. As of a November 29, 2017 data cut-off, all subjects remained relapse-free, and there were no events of graft failure and no serious adverse events related to ProTmune reported by investigators. Non-relapse mortality was reported in two subjects (Subject 1 on Day 228; Subject 3 on Day 151). Five of seven subjects remained on study with median time on study of 154 days [Day 106 — 254].

PROTECT Phase 2 Design
The Phase 2 stage of PROTECT is a randomized, controlled and double-blinded clinical trial assessing the safety and efficacy of ProTmune in up to 60 adult subjects with hematologic malignancies undergoing matched unrelated donor HCT following myeloablative conditioning. Subjects are being randomized, in a 1:1 ratio, to receive either ProTmune or a conventional matched unrelated donor mobilized peripheral blood cell graft. The primary efficacy endpoint of PROTECT is cumulative incidence of Grades 2-4 acute GvHD by Day 100 following HCT, where prospective clinical studies have shown that 40% to 80% of patients undergoing matched unrelated donor transplant experience Grades 2-4 acute GvHD. Immunosuppressant treatments are effective in only about half of affected HCT patients and are associated with a marked increase in severe infections and cancer relapse. Additional endpoints, such as rates of cancer relapse, chronic GvHD, non-relapse mortality and overall survival, are also being assessed. Fourteen U.S. centers are currently open for enrollment in the Phase 2 stage of PROTECT.

About Acute GvHD
Acute graft-versus-host disease (GvHD) is a severe immunological disease that commonly arises in patients during the first weeks following allogeneic HCT when newly-transplanted donor immune cells attack the patient’s tissues and organs, resulting in a potentially fatal immune system reaction. Prospective clinical studies have shown that 40% to 80% of patients undergoing matched unrelated donor transplant experience Grades 2-4 acute GvHD, with most incidents occurring by Day 60 following HCT despite the use of standard prophylaxis regimens. The disease is the leading cause of early morbidity and mortality in matched unrelated donor transplant, where death directly attributable to acute GvHD or its treatment occurs in 10% to 20% of patients. There are currently no FDA-approved preventive therapies and very few treatment options for acute GvHD.

About ProTmune
ProTmune is an investigational next-generation hematopoietic cell graft for the prevention of acute graft-versus-host disease (GvHD) in patients undergoing allogeneic hematopoietic cell transplantation. ProTmune is manufactured by pharmacologically modulating a donor-sourced, mobilized peripheral blood graft ex vivo with two small molecules (FT1050 and FT4145) to decrease the morbidity and mortality of acute GvHD while maintaining the anti-leukemia activity of the graft. ProTmune has been granted Orphan Drug and Fast Track Designations by the U.S. Food and Drug Administration, and Orphan Medicinal Product Designation by the European Commission.