Gamma-Delta T-cell Therapy Shows Durable Complete Responses in Acute Myeloid Leukemia

IN8bio’s INB-100, an allogeneic gamma-delta T-cell therapy, has shown durable efficacy in early data from 3 patients with acute myeloid leukemia (AML) undergoing haploidentical hematopoietic stem cell transplant (HSCT) who were dosed in a phase 1 clinical trial (NCT03533816).¹

Despite being at high risk of relapse, the 3 patients remain progression-free at 12.5, 24.2, and 26.5 months post-transplant, respectively. Additionally, no dose-limiting toxicities nor serious treatment emergent adverse events have been observed.

“We are excited about the early signals of long-term durable responses from gamma-delta T-cell therapy in these high-risk AML patients with complex cytogenetics,” Trishna Goswami, MD, chief medical officer of IN8bio, said in a statement.¹ “Despite the up to 51% anticipated one-year relapse rate of the patients enrolled in the trial, all 3 remain alive and disease free for more than one-year post-transplant. These data are highly encouraging, with the potential to increase the rates of cures in AML patients without significant added toxicities observed to date.”

At 6 months post-treatment, the patients’ immune systems showed normal function with elevations in levels of T-cells, B-cells, and gamma-delta T-cells. One patient experienced a grade 2 case of gastrointestinal tract (GI) graft–vs host disease (GvHD). All 3 of the patients experienced cases of grade 2 skin GvHD, which have resolved for 2 patients, while 1 patient continues to be treated with Jakafi.

The single-center, dose-escalation trial is anticipated to enroll 38 participantsage 18 to 65 with AML in morphologic complete remission with intermediate/high-risk features or relapsed disease, chronic myeloid leukemia, myelodysplastic syndrome with intermediate/high-risk features or refractory disease, or acute lymphoblastic leukemia with intermediate/high-risk features or relapsed disease. Patients with active central nervous system neoplastic involvement, a body mass index greater than 35, allergy to DMSO, and patients who are HIV1- or HIV2-positive or pregnant or breastfeeding will be excluded from the study.

Patients will receive gamma-delta T-cells, expanded and activated ex vivo, from matched related donors following haploidentical HSCT. Primary end points include the occurrence of dose-limiting toxicities and severe acute adverse events following treatment in the dose-finding part of the study, and the rate of acute GvHD in the expansion phase. Secondary end points include the rate of 1-year relapse-free survival, the rate of 1-year relapse mortality, the rate of 1-year overall survival, and the proportion of participants with chronic GvHD at 1 year. In the expansion phase, overall survival, relapse, and non-relapse mortality will also be evaluated.

The results described above will be discussed by William Ho, chief executive officer and co-founder, IN8bio, at the 3rd Annual Gamma-Delta T Therapies Summit being held from July 26 to 28 in Boston, Massachusetts.

The clinical trial has recruited additional patients, and further data is expected to be released in late 2022. The study’s estimated completion date is January 2023.

REFERENCE

IN8bio observes durable morphologic complete responses in ongoing phase 1 clinical trial of INB-100, an allogeneic gamma-delta T cell therapy in high-risk leukemia patients. News release. IN8bio, Inc. July 27, 2022. https://investors.in8bio.com/news-releases/news-release-details/in8bio-observes-durable-morphologic-complete-responses-ongoing