Introduction
Early T cell precursor acute lymphoblastic leukemia (ETP ALL) is a
relatively new, high-risk subgroup of acute lymphoblastic leukemia (ALL)
characterized by unique immune-phenotype and disease biology. ETP ALL
cells share similarities with hematopoietic stem cells and myeloid
progenitor cells [1]. Immuno-phenotypically it is characterized by
CD1a−, CD8−,
CD5− (dim), and positivity for 1 or more stem cell or
myeloid antigens [2]. As compared to patients with non ETP-ALL,
these patients have lower rates of complete remission (73% vs
91%; P = .03) and overall survival (OS)(20 months versus not
reached, P = .008). ETP ALL has been shown to be BCL 2 dependent
and is sensitive to in vitro inhibition by BCL2 inhibitors [3].
Venetoclax is an orally bioavailable BCL 2 inhibitor approved for use in
acute myeloid leukemia, chronic lymphocytic leukemia and multiple
myeloma [4]. Response of relapsed refractory T cell ALL with
venetoclax based therapy have been reported in literature. We present
the treatment outcomes of 2 patients with ETP ALL treated with
venetoclax.