Selective induction of apoptosis in leukemic B-lymphoid cells by a CD19-specific TRAIL fusion protein

Abstract

Although the treatment outcome of lymphoid malignancies has improved in recent years by the introduction of transplantation and antibody-based therapeutics, relapse remains a major problem. Therefore, new therapeutic options are urgently needed. One promising approach is the selective activation of apoptosis in tumor cells by the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). This study investigated the pro-apoptotic potential of a novel TRAIL fusion protein designated scFvCD19:sTRAIL, consisting of a CD19-specific single-chain Fv antibody fragment (scFv) fused to the soluble extracellular domain of TRAIL (sTRAIL). Potent apoptosis was induced by scFvCD19:sTRAIL in several CD19-positive tumor cell lines, whereas normal blood cells remained unaffected. In mixed culture experiments, selective binding of scFvCD19:sTRAIL to CD19-positive cells resulted in strong induction of apoptosis in CD19-negative bystander tumor cells. Simultaneous treatment of CD19-positive cell lines with scFvCD19:sTRAIL and valproic acid (VPA) or Cyclosporin A induced strongly synergistic apoptosis. Treatment of patient-derived acute B-lymphoblastic leukemia (B-ALL) and chronic B-lymphocytic leukemia (B-CLL) cells resulted in strong tumoricidal activity that was further enhanced by combination with VPA. In addition, scFvCD19:sTRAIL prevented engraftment of human Nalm-6 cells in xenotransplanted NOD/Scid mice. The pre-clinical data presented here warrant further investigation of scFvCD19:sTRAIL as a potential new therapeutic agent for CD19-positive B-lineage malignancies.

Recombinant human CD19L-sTRAIL effectively targets B cell precursor acute lymphoblastic leukemia

“…only on 2 to 3 consecutive days, CD19L-sTRAIL showed promising in vivo antileukemic activity in NOD/SCID mouse xenograft models of relapsed BPL. CD19L-sTRAIL exhibited (a) potent in vitro antileukemic activity at 3 log lower concentrations and (b) potent in vivo antileukemic activity at 3 log lower dose levels than scFvCD19: sTRAIL, another CD19-specific sTRAIL fusion protein (Mr: 47 kDa) in which the scFv of an anti-CD19 mAb was genetically linked to sTRAIL (42). In contrast to CD19L-sTRAIL and scFvCD19:sTRAIL, even nanomolar concentrations of recombinant sTRAIL induced apoptosis in less than 25% of BPL cases (37).…”

A novel AML-selective TRAIL fusion protein that is superior to Gemtuzumab Ozogamicin in terms of in vitro selectivity, activity and stability

“…This data corroborates with favorable toxicity profiles that we reported earlier for a series of analogous scFv:sTRAIL fusion proteins directed to various tumorassociated antigens, including CD7, CD19, CD20, EpCAM, and EGFR. [16][17][18][19][20]25 None of these fusion protein variants showed signs of toxicity towards normal blood cells, endothelia cells and hepatocytes. [16][17][18][19][20]25 From this we conclude that the intrinsic tumor-selective activity of sTRAIL is fully retained in the scFvCD33:sTRAIL fusion protein.…”

TRAIL/TRAIL‐R in hematologic malignancies

“…Another approach was proposed for B-ALL, based on the use of a TRAIL fusion protein designated scFvCD19:sTRAIL, consisting of a CD19-speciifc single-chain Fv antibody fragment (scFv) fused to the soluble extracellular domain of TRAIL (sTRAIL). scFvC19:sTRAIL induced apoptosis of primary B-ALL cells, consistently potentiated by concomitant addition of the histone deacetylase inhibitor valproic acid [Stiegmailer et al, 2008].…”