MALT1 Inhibition Is Efficacious in Both Naïve and Ibrutinib-Resistant Chronic Lymphocytic Leukemia.

The clinical efficacy displayed by ibrutinib in chronic lymphocytic leukemia (CLL) has been challenged by the frequent emergence of resistant clones. The ibrutinib target, Bruton's tyrosine kinase (BTK), is essential for B-cell receptor signaling, and most resistant cases carry mutations in BTK or PLCG2, a downstream effector target of BTK. Recent findings show that MI-2, a small molecule inhibitor of the para-caspase MALT1, is effective in preclinical models of another type of BCR pathway-dependent lymphoma. We therefore studied the activity of MI-2 against CLL and ibrutinib-resistant CLL. Treatment of CLL cells in vitro with MI-2 inhibited MALT1 proteolytic activity reduced BCR and NF-κB signaling, inhibited nuclear translocation of RelB and p50, and decreased Bcl-xL levels. MI-2 selectively induced dose and time-dependent apoptosis in CLL cells, sparing normal B lymphocytes. Furthermore, MI-2 abrogated survival signals provided by stromal cells and BCR cross-linking and was effective against CLL cells harboring features associated with poor outcomes, including 17p deletion and unmutated IGHV Notably, MI-2 was effective against CLL cells collected from patients harboring mutations conferring resistance to ibrutinib. Overall, our findings provide a preclinical rationale for the clinical development of MALT1 inhibitors in CLL, in particular for ibrutinib-resistant forms of this disease. Cancer Res; 77(24); 7038-48. ©2017 AACR.

Serum B-cell maturation antigen is elevated in multiple myeloma and correlates with disease status and survival.

Although TNFRSF17 (also designated as B-cell maturation antigen (BCMA)) is expressed on tumour cells in B-cell malignancies, it has not been found in serum. The present study found that BCMA concentrations were higher in the supernatants of cultured bone marrow mononuclear cells from multiple myeloma (MM) patients than in healthy subjects. Serum BCMA levels were measured in samples from MM patients (n = 209), monoclonal gammopathy of undetermined significance (MGUS) individuals (n = 23) and age-matched controls (n = 40). BCMA was detected in the serum of untreated MM patients (n = 50) and levels were higher than in MGUS patients (P = 0·0157) and healthy subjects (P < 0·0001). Serum BCMA levels were higher among patients with progressive disease (n = 80) compared to those with responsive disease (n = 79; P = 0·0038). Among all MM patients, overall survival was shorter among patients whose serum BCMA levels were above the median (P = 0·001). We also demonstrated that sera from mice with human MM xenografts contained human BCMA, and levels correlated with the change in tumour volume in response to melphalan or cyclophosphamide with bortezomib. These results suggest that serum BCMA levels may be a new biomarker for monitoring disease status and overall survival of MM patients.

Anti-myeloma effects of the novel anthracycline derivative INNO-206.

PURPOSE: Doxorubicin has shown efficacy especially in combination treatment for the treatment of multiple myeloma; however, its side effects limit its use. INNO-206 is an albumin-binding prodrug of doxorubicin, which is released from albumin under acidic conditions. Because INNO-206 has not been previously evaluated in any hematologic malignancy, we determined its anti-multiple myeloma effects. EXPERIMENTAL DESIGN: The anti-multiple myeloma effect of INNO-206 at different pH levels on multiple myeloma cell proliferation using multiple myeloma cell lines with the MTS assay and antiangiogenic activity using the chorioallantoic membrane/feather bud assay were determined. The anti-multiple myeloma effects and toxicity of INNO-206 were also compared with conventional doxorubicin and PEGylated liposomal doxorubicin (PLD) alone, and in combination with bortezomib, using our multiple myeloma xenograft models. RESULTS: INNO-206 inhibited blood vessel formation and reduced multiple myeloma cell growth in a pH-dependent fashion. INNO-206 alone produced marked anti-multiple myeloma effects in vivo at doses that doxorubicin was toxic, and the combination of INNO-206 plus bortezomib produced increased anti-multiple myeloma effects compared with either agent alone. In contrast, all mice receiving bortezomib with doxorubicin or PLD died. CONCLUSIONS: These findings show that INNO-206 produces anti-multiple myeloma effects in vitro and in vivo. It also enhances the antitumor effects of bortezomib. These results suggest that INNO-206 may provide patients with multiple myeloma with an anthracycline that may be administered safely at higher doses compared with free doxorubicin, resulting in superior efficacy compared with the currently available anthracyclines to treat this B-cell malignancy.