Subject terms
cytopenia
CYTOPENIA
Persistent cytopenia in the post-hematopoietic cell transplantation (HCT) setting can occur despite adequate engraftment of donor cells. PLX-R18, a placental-derived mesenchymal-like cell product, is expanded ex vivo in a 3-dimensional environment. PLX-R18 cells secrete a large array of hematopoietic factors, which promote regeneration, maturation, and differentiation of hematopoietic cells and stimulate their migration to peripheral blood. This phase 1, first-in-human study (NCT03002519), included 21 patients with incomplete hematopoietic recovery post-HCT. Patients were treated with escalating doses of PLX-R18: 3 patients received 1 million cells/kg, 6 received 2 million cells/kg, and 12 received 4 million cells/kg via multiple intramuscular injections. While patients received only two administrations of cells during the first week, peripheral blood counts continued to increase for months, peaking at 6 months for hemoglobin (Hb, 