Here we report that resistance to the BCL-2 targeting drug ABT-199 in models of mantle cell lymphoma and double-hit lymphoma evolves from outgrowth of persister clones displaying loss of 18q21 amplicons that harbor BCL2.
Dual targeting BTK and BCL2 with ibrutinib and venetoclax has improved outcomes in MCL patients who were predicted not to respond to conventional therapy, but it is unlikely to be curative.
Numerous studies have demonstrated many genetic aberrations in MCL in addition to the characteristic t(11:14), including frequent biallelic deletions of Bim, a proapoptotic member of the BCL-2 family.
In this study involving historical controls, dual targeting of BTK and BCL2 with ibrutinib and venetoclax was consistent with improved outcomes in patients with mantle-cell lymphoma who had been predicted to have poor outcomes with current therapy.
We demonstrate that DLBCL and MCL cell lines, primary patient samples, and PDX mouse models expressing high BCL-2 levels are extremely sensitive to venetoclax treatment.
To identify such combinations, we previously performed a combinatorial drug screen and identified the Bcl-2 inhibitor venetoclax (VEN) as a promising partner for combination with IBR in Mantle Cell Lymphoma (MCL).
High-throughput drug-sensitivity testing of MCL cells before and after ROR1 targeting revealed synergistic effects between cotargeting of ROR1 and the B-cell antigen receptor (BCR) or Bcl-2 family, underlining the high potential for ROR1-targeted therapies in overcoming MCL drug resistance.
On immunohistochemistry, the cells were positive for cyclin D1, CD20, CD21, SOX-11, and Bcl-2, but negative for CD3 and CD10; these findings were compatible with a diagnosis of MCL.
Apoptosis was evidenced by enhanced cleavage of Caspase-8/-9/-3 and poly (ADP-ribose) polymerase (PARP), and reduced anti-apoptotic proteins, including B-cell leukemia/lymphoma 2 (Bcl-2), mantle cell lymphoma (Mcl)-1, and Survivin.
Imbalances in the composition of BCL2 family proteins contribute to tumourigenesis and therapy resistance of mantle cell lymphoma (MCL), making these proteins attractive therapy targets.
Both cases showed near total effacement of the lymph node architecture by grade 1 FL (CD10+ and BCL2+) with accompanying in situ MCL component (CD5+ and cyclin D1+) surrounding neoplastic follicles.
The molecular characteristics of the t(14;18)/IGH-MALT1 resemble those found in the t(14;18)/IGH-BCL2 in follicular lymphoma and t(11;14)/CCND1-IGH in mantle cell lymphoma, suggesting that these translocations could be generated by common pathomechanisms involving illegitimate V(D)J-mediated recombination on IGH as well as new synthesis of T-nucleotides and nonhomologous end joining (NHEJ) or alternative NHEJ repair pathways on the IGH-translocation partner.
Fluorescence in situ hybridization studies demonstrated the presence of t(11;14)(q13;q32) involving BCL1, but not chromosomal translocations involving C-MYC or BCL2, confirming the diagnosis of MCL.
Apoptosis induction by BL22 was much more pronounced in MCL cell lines with low Bcl-2 expression (NCEB-1, JeKo-1 and JVM-2) compared to Granta-519 cells with high Bcl-2 expression.
In this study, we investigated the cell signaling pathways activated in bcl-2-overexpressing human mantle cell lymphoma cell lines (JVM-2 and Z-138) that have been treated with oblimersen, a molecular gene silencing strategy that effectively suppresses bcl-2 in vitro and in vivo.