TAK1-inhibitors did not reduce disease burden in a Vκ*MYC model of multiple myeloma.

OBJECTIVE: Multiple myeloma is a haematological malignancy characterized by proliferation of monoclonal plasma cells in the bone marrow. Development of resistance and minimal residual disease remain challenging in the treatment of multiple myeloma. Transforming growth factor-ß activated kinase 1 (TAK1) has recently gained attention as a potential drug target in multiple myeloma. This study aimed at determining the in vivo effects of TAK1-inhibitors in a Vκ*MYC multiple myeloma mouse model. RESULTS: We treated mice carrying Vκ*MYC multiple myeloma cells with the TAK1-inhibitors 5Z-7-oxozeaenol and NG25. There were tendencies towards increased survival for both inhibitors, but only NG25 prolonged survival significantly. However, this effect was limited, and no differences in disease burden were observed for any of the treatments. In conclusion, although TAK1-inhibitors might prolong survival somewhat, they do not prevent disease in the Vκ*MYC mouse model of multiple myeloma.

Empirical antimicrobial therapy for bloodstream infections not compliant with guideline was associated with discordant therapy, which predicted poorer outcome even in a low resistance environment.

OBJECTIVES: To characterise all bloodstream infections (BSIs) in a low antimicrobial resistance (AMR) prevalence setting with regard to the appropriateness of empirical antimicrobial therapy, compliance with the national clinical practice guideline, de-escalation practice and outcome. METHODS: A retrospective observational study including patients aged ≥ 18 years admitted to a university hospital in central Norway with positive blood culture in 2019. RESULTS: We included 756 BSI episodes in our analysis. Empirical antimicrobial therapy was in accordance with the national guideline in 534 (70.6%), and not in accordance in 190 (25.1%) of the BSI episodes. There was a statistically significant association between compliance with the national guideline and concordant empirical antimicrobial therapy (p = .001). De-escalation of antimicrobial therapy was possible but not done in 217 (31.1%) of the BSI episodes. Variables identified as independent predictors of discordant empirical antimicrobial therapy included hospital department, type of empirical antimicrobial regimen, bacterial species, and AMR. Independent predictors of intra-hospital case fatality rate were coverage of empirical antimicrobial therapy, CCI-score, SAPS-II score, site of infection, and type of empirical antimicrobial regimen. Furthermore, the intra-hospital and long-term unadjusted all-cause case fatality rates were increased (p < .001, log-rank test for overall difference in survival) for the patients who received discordant empirical antimicrobial therapy. CONCLUSION: Our study shows that empirical antimicrobial therapy initiated in accordance with national guideline recommendations increases the likelihood of receiving concordant therapy. Discordant empirical antimicrobial therapy was associated with poorer outcomes, even in a setting with low AMR prevalence.

TAK1-inhibitors are cytotoxic for multiple myeloma cells alone and in combination with melphalan.

Multiple myeloma (MM) is an incurable cancer caused by malignant transformation of plasma cells. Transforming growth factor-ß activated kinase 1 (MAP3K7, TAK1) is a major regulator of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and mitogen-activated protein kinase (MAPK) signaling. Both NF-κB and MAPK control expression of genes with vital roles for drug resistance in MM. TAK1 is an attractive drug target as it switches these survival pathways to cell death. Our analysis showed that patients with high MAP3K7 expression in the tumor had shorter overall and progression free survival. The TAK1-inhibitors NG25 and 5Z-7-oxozeaenol (5Z-7) were cytotoxic to MM cell lines and patient cells. NG25 reduced expression of MYC and E2F controlled genes, involved in tumor cell growth, cell cycle progression and drug resilience. TAK1 can be activated by genotoxic stress. NG25 and 5Z-7 induced both synergistic and additive cytotoxicity in combination with the alkylating agent melphalan. Melphalan activated TAK1, NF-κB, and the MAPKs p38 and c-Jun N-terminal kinase (JNK), as well as a transcriptional UV-response. This was blocked by NG25, and instead apoptosis was activated. MM induce elevated bone-degradation resulting in myeloma bone disease (MBD), which is the main cause of disability and morbidity in MM patients. NG25 and 5Z-7 reduced differentiation and viability of human bone degrading osteoclasts, suggesting that TAK1-inhibition can have a double beneficial effect for patients. In sum, TAK1 is a promising drug target for MM treatment.

Smac-mimetics reduce numbers and viability of human osteoclasts.

Elevated activity of bone-degrading osteoclasts (OC) contributes to pathological bone degradation in diseases such as multiple myeloma. Several proinflammatory cytokines, including TNF, contribute to osteoclastogenesis. The receptor-interacting protein kinase 1 (RIPK1) regulates inflammation and cell death. It is recruited to the TNF-receptor complex, where it is ubiquitinated, and activates transcription factor NF-κB and mitogen-activated protein kinases (MAPK). Smac-mimetics (SM) is a group of drugs that block RIPK1 ubiquitination and shifts RIPK1 to activation of apoptosis or necroptosis. In this manuscript, we show that the two SM birinapant and LCL-161 reduced the number and viability of primary human OC, and induced TNF-dependent cell death in OC precursors (pre-OC). Birinapant was more cytotoxic than LCL-161 and induced predominantly apoptosis and to some degree necroptosis. Both inhibitors restrained osteoclastogenesis induced by myeloma patient bone-marrow aspirates. SM has gained attention as novel treatment strategies both for cancer and chronic inflammatory pathologies, but limited information has been available on interactions with primary human immune cells. As LCL-161 is in phase 2 clinical studies for multiple myeloma, we propose that SM might possess additional benefits in reducing bone degradation in myeloma patients. Taken together, we show that SM reduces human osteoclastogenesis, and that these compounds may represent promising drug candidates for pathological bone degradation.