Oral ixazomib maintenance therapy in multiple myeloma

Comparative effectiveness of lenalidomide/dexamethasone-based triplet regimens for treatment of relapsed and/or refractory multiple myeloma in the United States: An analysis of real-world electronic health records data

BACKGROUND

This retrospective longitudinal study compared the effectiveness of dexamethasone+lenalidomide (Rd)-based triplet regimens containing proteasome inhibitors (PIs) ixazomib (IRd), carfilzomib (KRd), and bortezomib (VRd) or monoclonal antibodies (MABs) elotuzumab (ERd) and daratumumab (DRd) in patients with relapsed/refractory multiple myeloma (RRMM)-including those with high cytogenetic risk-primarily treated at community oncology clinics in the United States.

METHODS

Electronic health records of adult RRMM patients in a deidentified real-world database (01/01/2014-09/30/2020) who initiated IRd, KRd, VRd, ERd, or DRd in the second or later line of therapy (LOT) were analyzed. The index date was the date of initiation of each LOT and baseline was the 6-month pre-index period. Duration of therapy (DOT), time to next therapy (TTNT), progression-free survival (PFS), and overall survival (OS) were compared across regimens with multivariable Cox proportional hazards models.

RESULTS

Of the 1,185 patients contributing 1,332 LOTs, 985 had standard cytogenetic risk (median age, 71 years) and 180 had high risk (median age, 69 years). Compared with other regimens, DRd was associated with longer DOT overall (adjusted hazard ratio [95 % confidence interval]: 1.84 [1.42, 2.38] vs. KRd, 1.65 [1.20, 2.28] vs. ERd, 1.58 [1.23, 2.04] vs. IRd, and 1.54 [1.18, 2.00] vs. VRd), and longer TTNT and PFS. KRd was associated with shorter OS compared with DRd (1.45 [1.01, 2.08]) and VRd (1.32 [1.01, 1.73]). High-risk patients had similar outcomes with all triplet regimens.

CONCLUSION

Although DRd improved clinical outcomes overall, Rd-based triplet regimens containing a PI or MAB are similarly effective in high-risk RRMM.

Epigenetic Alterations as Vital Aspects of Bortezomib Molecular Action

Bortezomib (BTZ) is widely implemented in the treatment of multiple myeloma (MM). Its main mechanism of action is very well established. BTZ selectively and reversibly inhibits the 26S proteasome. More precisely, it interacts with the chymotryptic site of the 20S proteasome and therefore inhibits the degradation of proteins. This results in the intracellular accumulation of misfolded or otherwise defective proteins leading to growth inhibition and apoptosis. As well as interfering with the ubiquitin-proteasome complex, BTZ elicits various epigenetic alterations which contribute to its cytotoxic effects as well as to the development of BTZ resistance. In this review, we summarized the epigenetic alterations elicited by BTZ. We focused on modifications contributing to the mechanism of action, those mediating drug-resistance development, and epigenetic changes promoting the occurrence of peripheral neuropathy. In addition, there are therapeutic strategies which are specifically designed to target epigenetic changes. Herein, we also reviewed epigenetic agents which might enhance BTZ-related cytotoxicity or restore the sensitivity to BTZ of resistant clones. Finally, we highlighted putative future perspectives regarding the role of targeting epigenetic changes in patients exposed to BTZ.

Ixazomib promotes CHOP-dependent DR5 induction and apoptosis in colorectal cancer cells

BACKGROUND

Ixazomib (Ninlaro), a novel proteasome inhibitor, has been developed for the treatment of many cancers and has demonstrated anti-tumor efficacy against various malignancies. However, the mechanism of the anti-tumor effect of ixazomib in colorectal cancer (CRC) cells remains unclear.

METHODS

MTS and flow cytometry were performed to determine the effect of ixazomib on CRC cells. Western blotting and real-time RT-PCR were performed to detect ixazomib-induced DR5 upregulation. ChIP was performed to detect CHOP binding to DR5 promoter. Finally, xenograft experiments were carried out to measure the antitumor effect of ixazomib in vivo.

RESULTS

In this study, we revealed the mechanism by which ixazomib inhibits the growth of CRC cells. Our findings indicated that ixazomib treatment induces CHOP-dependent DR5 induction, irrespective of p53 status. Furthermore, DR5 is necessary for ixazomib-mediated apoptosis. Ixazomib also synergized with TRAIL to induce marked apoptosis via DR5 in CRC cells.

CONCLUSIONS

Our findings further suggested that ixazomib sensitizes TRAIL/death receptor signaling pathway-targeted CRC and suggested that DR5 induction could be a valuable indicator of ixazomib sensitivity.

Second-generation proteasome inhibitor carfilzomib sensitizes neuroblastoma cells to doxorubicin-induced apoptosis

Neuroblastoma (NB), which accounts for about 15% of cancer-related mortality in children, is the most common extracranial malignant neoplasm in children. Elevated level of proteasome activity promotes cancer development and the inhibition of proteasome activity is a promising strategy for cancer treatment. Therefore, targeting proteasome by small molecule inhibitors may be a viable option for NB therapy. Here in this study, we show that a novel proteasome inhibitor Carfilzomib (CFZ) exerts anti-tumor effect on NB. CFZ caused decreased cell viability and attenuated colony formation ability of a subset of NB cell lines. CFZ induced cell apoptosis in NB cells. Moreover, CFZ enhanced the cytotoxic effect of doxorubicin (Dox) on NB cells and Dox-induced p38 and JNK phosphorylation. In addition, CFZ inhibited Dox-induced NF-κB activation by stabilizing the protein level of IκBα. Furthermore, CFZ induced apoptosis and augmented Dox-induced apoptosis in NB tumor cells in orthotopic xenograft mouse models. In summary, our study suggests that proteasome is a therapeutic target in NB and proteasome inhibition by CFZ is a potential therapeutic strategy for treating NB patients.