Acute Lymphoblastic Leukemia

CD47 agonist peptide PKHB1 induces immunogenic cell death in T-cell acute lymphoblastic leukemia cells

T‐cell acute lymphoblastic leukemia (T‐ALL) has a poor prognosis derived from its genetic heterogeneity, which translates to a high chemoresistance. Recently, our workgroup designed thrombospondin‐1‐derived CD47 agonist peptides and demonstrated their ability to induce cell death in chronic lymphocytic leukemia. Encouraged by these promising results, we evaluated cell death induced by PKHB1 (the first‐described serum‐stable CD47‐agonist peptide) on CEM and MOLT‐4 human cell lines (T‐ALL) and on one T‐murine tumor lymphoblast cell‐line (L5178Y‐R), also assessing caspase and calcium dependency and mitochondrial membrane potential. Additionally, we evaluated selectivity for cancer cell lines by analyzing cell death and viability of human and murine non‐tumor cells after CD47 activation. In vivo, we determined that PKHB1‐treatment in mice bearing the L5178Y‐R cell line increased leukocyte cell count in peripheral blood and lymphoid organs while recruiting leukocytes to the tumor site. To analyze whether CD47 activation induced immunogenic cell death (ICD), we evaluated damage‐associated molecular patterns (DAMP) exposure (calreticulin, CRT) and release (ATP, heat shock proteins 70 and 90, high‐mobility group box 1, CRT). Furthermore, we gave prophylactic antitumor vaccination, determining immunological memory. Our data indicate that PKHB1 induces caspase‐independent and calcium‐dependent cell death in leukemic cells while sparing non‐tumor murine and human cells. Moreover, our results show that PKHB1 can induce ICD in leukemic cells as it induces CRT exposure and DAMP release in vitro, and prophylactic vaccinations inhibit tumor establishment in vivo. Together, our results improve the knowledge of CD47 agonist peptides potential as therapeutic tools to treat leukemia.

Acute lymphoblastic leukemia and lymphoblastic lymphoma in adolescents and young adults

Compared to younger and older age groups, the incidence of acute lymphoblastic leukemia (ALL) and lymphoblastic lymphoma (LBL) has increased more in the adolescent and young adult (AYA) population, the cause of which is unknown. As of the last decade, only half of the AYA patients with these diseases were surviving 10 years. Strong evidence exists that favors "pediatric" treatment regimens for AYAs compared to "adult" treatment regimens in terms of survival rates, hospitalization time, toxicities, late effects, and quality of life both during and after treatment. Targeted agents are clinically accessible for certain subsets of patients with Philadelphia-like ALL, the incidence of which peaks in AYAs. Treatment teams must appreciate the complex psychosocial underpinnings in these patients in order to maximize compliance with the prolonged and complex treatment plans during the AYA years.