Partner Therapeutics Announces Initiation of Clinical Trial Evaluating Leukine® in T Cell Replete HLA-mismatched Haploidentical Stem Cell Transplant

LEXINGTON, Mass., June 11, 2020 /PRNewswire/ -- Partner Therapeutics, a commercial biotechnology company, announces the enrollment of the first patient dosed in a Phase II investigator-initiated study evaluating the efficacy and safety of Leukine(®) (sargramostim, rhu-GM-CSF) in T cell replete HLA-mismatched haploidentical stem cell transplant recipients who are receiving post-transplant cyclophosphamide (NCT04237623).

The study will enroll patients with high risk hematologic malignancies who are the recipients of a haploidentical cell transplant. The trial will evaluate the effectiveness of Leukine compared to a matched control cohort of G-CSF treated patients, as well as evaluate the immune reconstitution profile of the treated patients compared to a contemporaneous cohort of 20 patients who receive G-CSF.

"Given the important role GM-CSF plays in differentiating and maturing monocytes and dendritic cells, we are eager to evaluate the impact Leukine has on reconstituting the immune system of haploidentical transplant recipients, as well as the effect it may have on rates of infection in this at-risk patient population," said Dr. Melhem Solh, principal investigator of this investigator-initiated study and a physician with The Blood and Marrow Transplant Group of Georgia and Northside Hospital.

"This study will provide data that are more relevant to the current practice of stem cell transplant," said Fiona Garner, executive director of translational medicine at Partner Therapeutics. "We believe that the effect Leukine has on maturing and differentiating monocytes and dendritic cells, as well as neutrophils, may be particularly helpful in the immune reconstitution of this haploidentical transplant population, which experiences higher rates of infection and longer time to engraftment than other transplant populations."

Leukine (sargramostim) is a recombinant human granulocyte-macrophage growth factor (rhuGM-CSF) that stimulates the differentiation, maturation and mobilization of cells involved in the innate and adaptive immune response. It has been shown to facilitate cellular signaling, epithelial repair, and other critical processes that enhance the immune response and help defend the body against infection and cancer. Leukine was first approved by the FDA in 1991 and has an established safety profile based on treatment in more than 500,000 patients. Partner Therapeutics acquired the rights to Leukine in 2018. Leukine is held by the U.S. Government in the Strategic National Stockpile for use during public health emergencies. Leukine is available outside of the United States through a Named Patient Program administered by Tanner Pharma Group.

Many patients with high risk hematologic malignancies receive allogeneic hematopoietic cell transplants from a matched sibling to reestablish their immune system after chemotherapy and radiation are used to deplete the patients original and now dysfunctional immune system. However, only one third of those who require a transplant have HLA-matched siblings, so other sources of stem cells are required. A partially matched or haploidentical donor is available for most patients since everyone shares one haplotype with their parents. In recent years, haploidentical transplantation has shown similar outcomes to matched transplant. The numbers of haploidentical transplants continue to increase and studies to help improve on the immune reconstitution and decrease infection rates warranted.

The phase II trial discussed above is titled "Phase II trial evaluating the Efficacy and Safety of Sargramostim Post Infusion of T -Replete HLA Mismatched Peripheral Blood Haploidentical Hematopoietic Stem Cells with Post-Transplant Cyclophosphamide." The study plans to enroll 38 patients in the treatment arm ages 18-78 with a high-risk malignancy who are the recipient of a 5/10-8/10 HLA-A, B, DR matched donor with a Karnofsky performance score ³70%. The primary endpoint of the study is to establish equivalent effectiveness of sargramostim to a matched control cohort of G-CSF treated patients in time to neutrophil engraftment post haploidentical HSCT with post-transplant cyclophosphamide. Secondary endpoints will evaluate overall survival and relapse rates, incidence of GVHD, donor chimerism, and detailed immune profiling up to six months. Additional details on the study may be found here.

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SOURCE Partner Therapeutics, Inc.