Activation of concurrent apoptosis and necroptosis by SMAC mimetics for the treatment of refractory and relapsed ALL

Abstract

More precise treatment strategies are urgently needed to decrease toxicity and improve outcomes for treatment-refractory leukemia. We used ex vivo drug response profiling of high-risk, relapsed, or refractory acute lymphoblastic leukemia (ALL) cases and identified a subset with exquisite sensitivity to small-molecule mimetics of the second mitochondria-derived activator of caspases (SMAC) protein. Potent ex vivo activity of the SMAC mimetic (SM) birinapant correlated with marked in vivo antileukemic effects, as indicated by delayed engraftment, decreased leukemia burden, and prolonged survival of xenografted mice. Antileukemic activity was dependent on simultaneous execution of apoptosis and necroptosis, as demonstrated by functional genomic dissection with a multicolored lentiCRISPR approach to simultaneously disrupt multiple genes in patient-derived ALL. SM specifically targeted receptor-interacting protein kinase 1 (RIP1)-dependent death, and CRISPR-mediated disruption of RIP1 completely blocked SM-induced death yet had no impact on the response to standard antileukemic agents. Thus, SM compounds such as birinapant circumvent escape from apoptosis in leukemia by activating a potent dual RIP1-dependent apoptotic and necroptotic cell death, which is not exploited by current therapy. Ex vivo drug activity profiling could provide important functional diagnostic information to identify patients who may benefit from targeted treatment with birinapant in early clinical trials.

Ex vivo drug response profiling detects recurrent sensitivity patterns in drug-resistant acute lymphoblastic leukemia

“…These included second mitochondrial activator of caspases (SMAC) mimetics (eg, LCL161), an observation that led us to show that a BCP-ALL subset was extremely responsive to SMAC mimetics through RIP1 kinase-dependent necroptosis and apoptosis. 37 The ABL/SRC inhibitor dasatinib is also highly active in a T-ALL subset discussed later in this article. High peak plasma concentrations (C max ) were reported for most clinical compounds in our panel (supplemental Figure 2), suggesting that effective concentrations may be achieved in vivo.…”

“…We and others 16,18 have demonstrated the use of drug profiling for identifying phenotypes that are responsive to new therapeutic agents. We have identified recurrent ALL patients who are highly sensitive to triggering RIP1-dependent cell death with SMAC mimetics 37 or to BCL2 inhibition in BCP-ALL subsets, including TCF3-HLF ALL 35 and T-ALL subsets. Moreover, we discovered a subgroup in T-ALL that is highly sensitive to dasatinib, which should be further evaluated first in patients with highly drugresistant and refractory disease.…”

Complex Pathologic Roles of RIPK1 and RIPK3: Moving Beyond Necroptosis

“…Similarly, BV6 was shown to efficiently kill apoptosis-resistant pancreatic cancer cells by necroptosis when combined with zVAD.fmk [142]. In contrast, analysis of refractory or relapsed acute lymphoblastic leukemia (ALL) patient samples identified a subset which was highly sensitive to brinipant alone [143]. In this case, specific activation of necroptosis by addition of caspase inhibitor was not necessary, as cells were efficiently eliminated by brinipant alone inducing a mixture of RIPK1 kinase-dependent apoptosis and necroptosis.…”

Burkitt lymphoma in adolescents and young adults: management challenges

“…Relative to B-lymphoid malignancies, venetoclax was found synergistic with vincristine and dexamethasone in B-precursor ALL expressing TCF3-HLF gene rearrangement,137 and TCF3 mutations are known to occur in BL. Another example concerns birinapant, an SMAC-mimetic inductor of necroptosis found effective against highly MRD-resistant cases of B-lineage ALL 138. In a study regarding another MYC -driven neoplasm (Group 3 medulloblastoma), an in silico analysis method for screening drug sensitivity databases resulted in the identification of new molecular targets (cyclin-dependent kinase) for these c-MYC -transformed cells 139…”