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ABSTRACT Isatuximab, a novel anti‐CD38 monoclonal antibody, is approved in combination with carfilzomib and dexamethasone (Isa‐Kd) in relapsed/refractory multiple myeloma (RRMM) patients. Because of its recent introduction, real‐world efficacy and safety are poorly reported. In this Italian multicenter real‐life observational retrospective study, efficacy and safety of the Isa‐Kd regimen were evaluated in a cohort of 103 RRMM patients. Overall response rate (ORR) was 85%, with stringent (sCR) or complete response (CR) in 18% of cases and very good partial response (VGPR) in 39%. Median PFS and OS were not reached within the study period, while 1‐year PFS and OS were 72% and 77%, respectively. Hematological toxicities were observed in 42% of subjects, and cardiac toxicities occurred in 24% of cases. Moreover, we conducted a subanalysis on patients (N = 69) treated with Isa‐Kd after one prior line of therapy, showing an ORR of 88%, with sCR + CR in 20% of subjects, VGPR in 46%, and PR in 22% of patients. In this group, median PFS and OS were not reached, while 1‐year PFS and OS were 92% and 95%, respectively. In conclusions, our study confirmed Isa‐Kd as an effective treatment option for RRMM with a manageable safety profile even in real‐life settings. [ABSTRACT FROM AUTHOR]

Induction chemotherapy followed by autologous haematopoietic cell transplantation and post‐transplant therapy (including maintenance therapy with or without prior consolidation) is still considered as the standard of care for newly diagnosed young and fit multiple myeloma patients. Over the last years, superiority of quadruplet regimens for induction was established, with the addition of an anti‐CD38 monoclonal antibody to triplet regimen including a proteasome inhibitor, an IMiD (thalidomide or lenalidomide) or cyclophosphamide, and dexamethasone. Given quadruplet induction regimens are associated with deep response, including a high‐rate of sustained measurable residual disease negativity in a significant proportion of patients, they are now recommended for induction chemotherapy when available. [ABSTRACT FROM AUTHOR]

The leading cause of cancer‐related death is lung cancer, with metastasis being the most common cause of death. To elucidate the role of macrophages in lung cancer and angiogenesis processes, we established an in vitro co‐culture model of A549 or HUVEC with THP‐1 cells that polarized to M2c macrophages with hydrocortisone. The proteasome inhibitors bortezomib and ixazomib were investigated for their effects on proliferation, invasion, migration, metastasis, and angiogenesis pathways. The effects of bortezomib and ixazomib on gene expression in gene panels, including crucial genes related to angiogenesis and proteasomes, were investigated after the co‐culture model to determine these effects at the molecular level. In conclusion, bortezomib and ixazomib showed antiproliferative effects in both cells, as well as in M2c macrophage co‐culture. M2c macrophages also increased invasion in A549 cells and both invasion and migration in HUVEC. mRNA expression upregulation, specifically in the NFKB and VEGF genes, supported the metastatic and angiogenic effects found in A549 and HUVEC with M2c macrophage co‐culture. Additionally, bortezomib inhibited the VEGFB pathway in HUVEC and NFKB1 in A549 cells. The significant findings obtained as a result of this study will provide information regarding angiogenesis induced by M2 macrophages. [ABSTRACT FROM AUTHOR]

Background: Belantamab mafodotin (belamaf) has shown promising antimyeloma activity in relapsed or refractory multiple myeloma (RRMM) as a single agent. It was hypothesized that its multimodal activity may be enhanced by programmed cell death protein 1 pathway inhibition and activation of T cell–mediated antitumor responses. This study investigated the efficacy and safety of belamaf with pembrolizumab in patients with RRMM. Methods: DREAMM‐4 (NCT03848845) was an open‐label, single‐arm, phase 1/2 study divided into dose‐escalation (part 1) and dose‐expansion (part 2) phases. Patients were ≥18 years old with ≥3 prior lines of therapy including a proteasome inhibitor, an immunomodulatory drug, and an anti‐CD38 agent. Patients received belamaf (2.5 or 3.4 mg/kg, part 1; 2.5 mg/kg, part 2) and 200 mg pembrolizumab for ≤35 cycles. Results: Of 41 enrolled patients, 34 (n = 6 part 1, n = 28 part 2) who received 2.5 mg/kg belamaf plus pembrolizumab were included in this final analysis. Sixteen patients (47%) achieved an overall response. Minimal residual disease negativity was achieved in three of 10 patients who had very good partial response or better. Five of eight patients who had prior anti–B‐cell maturation antigen therapy achieved partial response or better, including two who had B‐cell maturation antigen–refractory disease. Common grade ≥3 adverse events were keratopathy (38%) and thrombocytopenia (29%). Despite belamaf‐related ocular events, quality‐of‐life measures remained stable over time. No new safety signals were observed. Conclusions: The results of DREAMM‐4 demonstrated clinical activity and a favorable safety profile of belamaf plus pembrolizumab in patients with RRMM. This trial is registered at www.ClinicalTrials.gov as NCT03848845. [ABSTRACT FROM AUTHOR]

Objectives: To analyze the impact of prior therapies on outcomes with selinexor, bortezomib, and dexamethasone (SVd) versus bortezomib and dexamethasone (Vd) in 402 patients with relapsed/refractory multiple myeloma (RRMM) in the phase 3 BOSTON trial. Methods: Post hoc analysis of progression‐free survival (PFS), overall survival (OS), and safety for lenalidomide‐refractory, proteasome inhibitor (PI)‐naïve, bortezomib‐naïve, and one prior line of therapy (1LOT) patient subgroups. Results: At a median follow‐up of over 28 months, clinically meaningful improvements in PFS were noted across all groups with SVd. The median SVd PFS was longer in all subgroups (lenalidomide‐refractory: 10.2 vs. 7.1 months, PI‐naïve: 29.5 vs. 9.7; bortezomib‐naïve: 29.5 vs. 9.7; 1LOT: 21.0 vs. 10.7; p <.05). The lenalidomide‐refractory subgroup had longer OS with SVd (26.7 vs. 18.6 months; HR 0.53; p =.015). In all subgroups, overall response and ≥very good partial response rates were higher with SVd. The manageable safety profile of SVd was similar to the overall patient population. Conclusions: With over 2 years of follow‐up, these clinically meaningful outcomes further support the use of SVd in patients who are lenalidomide‐refractory, PI‐naïve, bortezomib‐naïve, or who received 1LOT (including a monoclonal antibody) and underscore the observed synergy between selinexor and bortezomib. [ABSTRACT FROM AUTHOR]

Objectives: To characterize the impact of prior exposure and refractoriness to lenalidomide or proteasome inhibitors (PIs) on the effectiveness and safety of ixazomib–lenalidomide–dexamethasone (IRd) in relapsed/refractory multiple myeloma (RRMM). Methods: INSURE is a pooled analysis of adult RRMM patients who had received IRd in ≥2 line of therapy from three studies: INSIGHT MM, UVEA‐IXA, and REMIX. Results: Overall, 391/100/68 were lenalidomide‐naïve/−exposed/−refractory and 37/411/110 were PI‐naïve/−exposed/−refractory. Median duration of therapy (DOT) was 15.3/15.6/4.7 months and median progression‐free survival (PFS) was 21.6/25.8/5.6 months in lenalidomide‐naïve/exposed/refractory patients. Median DOT and PFS in PI‐naïve/exposed/refractory patients were 20.4/15.2/6.9 months and not reached/19.8/11.4 months, respectively. The proportion of lenalidomide‐naïve/exposed/refractory patients in INSIGHT and UVEA‐IXA who discontinued a study drug due to adverse events (AEs) was ixazomib, 31.6/28.2/28.0% and 18.6/6.7/10.5%; lenalidomide, 21.9/28.2/16.0% and 16.1/6.7/10.5%; dexamethasone, 18.4/20.5/16.0% and 10.6/0/10.5%, respectively. The proportion of PI‐naïve/exposed/refractory patients in INSIGHT and UVEA‐IXA who discontinued a study drug due to AEs was: ixazomib, 44.4/28.8/27.8% and 22.2/16.7/15.7%; lenalidomide, 33.3/22.0/19.4% and 16.7/15.9/11.8%; dexamethasone, 33.3/17.4/16.7% and 16.7/9.5/7.8%, respectively. REMIX AE discontinuation rates were unavailable. Conclusion: IRd appeared to be effective in RRMM patients in routine clinical practice regardless of prior lenalidomide or PI exposure, with better outcomes seen in lenalidomide‐ and/or PI‐nonrefractory versus refractory patients. [ABSTRACT FROM AUTHOR]

Objective: TQB3602 is a novel orally bioavailable proteasome inhibitor. This study is the first‐in‐human phase I clinical trial to evaluate the safety, tolerability, pharmacokinetics, and preliminary efficacy of TQB3602 in relapsed/refractory multiple myeloma (RRMM). Methods: This is a multicenter phase I clinical trial consisting of the 3+3 dose‐escalation phase and dose expansion phase. Patients with MM who have received ≥2 prior antimyeloma therapies were enrolled. TQB3602 is administered at a dose of 0.5~7mg on days 1, 8, 15 in 28‐day cycle. Results: Twenty‐five RRMM patients who relapsed or failed ≥2 lines of therapies were enrolled in the dose escalation phase. Two patients in the 7.0 mg dose group developed dose‐limiting toxicity events (one with grade 2 peripheral neuropathy [PN] complicated by pain and one with diarrhea and abdominal pain), leading to a maximum tolerated dose of 6.0 mg. Any‐grade adverse events (AEs) occurred in 24 (96.0%) patients, while grade ≥3 AEs occurred in 13 (52.0%). The most common grade ≥3 AEs was anemia (6, 24.0%). The incidence rate of PN was 16% with no grade ≥3 PN occurred. TQB3602 was rapidly absorbed, resulting in a time‐to‐plasma peak concentration of 0.8–1.5 h. The mean half‐life was approximately 82 h. The AUClast and Cmax were approximately 1.9 times higher on day 15 than on day 1. Among 22 response‐evaluable patients, 63.7% achieved stable disease or better. Conclusions: TQB3602 is well tolerated, with a favorable neurotoxicity profile, and has shown preliminary efficacy in patients with RRMM. The anticipated therapeutic dose was 6 mg and was adopted for an ongoing dose‐expansion phase. [ABSTRACT FROM AUTHOR]

Minute virus of canines (MVC) belongs to the genus Bocaparvovirus (formerly Bocavirus) within the Parvoviridae family and causes serious respiratory and gastrointestinal symptoms in neonatal canines worldwide. A productive viral infection relies on the successful recruitment of host factors for various stages of the viral life cycle. However, little is known about the MVC‐host cell interactions. In this study, we identified that two cellular proteins (Hsc70 and Hsp70) interacted with NS1 and VP2 proteins of MVC, and both two domains of Hsc70/Hsp70 were mediated for their interactions. Functional studies revealed that Hsp70 was induced by MVC infection, knockdown of Hsc70 considerably suppressed MVC replication, whereas the replication was dramatically promoted by Hsp70 knockdown. It is interesting that low amounts of overexpressed Hsp70 enhanced viral protein expression and virus production, but high amounts of Hsp70 overexpression weakened them. Upon Hsp70 overexpressing, we observed that the ubiquitination of viral proteins changed with Hsp70 overexpression, and proteasome inhibitor (MG132) restored an accumulation of viral proteins. In addition, we verified that Hsp70 family inhibitors remarkably decreased MVC replication. Overall, we identified Hsc70 and Hsp70 as interactors of MVC NS1 and VP2 proteins and were involved in MVC replication, which may provide novel targets for anti‐MVC approach. [ABSTRACT FROM AUTHOR]

Serine/threonine‐protein kinase B‐raf (BRAF) mutations are found in 8–15% of colorectal cancer patients and identify a subset of tumors with poor outcome in the metastatic setting. We have previously reported that BRAF‐mutant human cells display a high rate of protein production, causing proteotoxic stress, and are selectively sensitive to the proteasome inhibitors bortezomib and carfilzomib. In this work, we tested whether carfilzomib could restrain the growth of BRAF‐mutant colorectal tumors not only by targeting cancer cells directly, but also by promoting an immune‐mediated antitumor response. In human and mouse colorectal cancer cells, carfilzomib triggered robust endoplasmic reticulum stress and autophagy, followed by the emission of immunogenic‐damage‐associated molecules. Intravenous administration of carfilzomib delayed the growth of BRAF‐mutant murine tumors and mobilized the danger‐signal proteins calreticulin and high mobility group box 1 (HMGB1). Analyses of drug‐treated samples revealed increased intratumor recruitment of activated cytotoxic T cells and natural killers, concomitant with the downregulation of forkhead box protein P3 (Foxp3)+ T‐cell surface glycoprotein CD4 (CD4)+ T cells, indicating that carfilzomib promotes reshaping of the immune microenvironment of BRAF‐mutant murine colorectal tumors. These results will inform the design of clinical trials in BRAF‐mutant colorectal cancer patients. [ABSTRACT FROM AUTHOR]

Pulmonary vascular remodeling is a key pathological process of pulmonary arterial hypertension (PAH), characterized by uncontrolled proliferation and migration of pulmonary arterial smooth muscle cells (PASMCs). Bortezomib (BTZ) is the first Food and Drug Administration (FDA)‐approved proteasome inhibitor for multiple myeloma treatment. Recently, there is emerging evidence showing its effect on reversing PAH, although its mechanisms are not well understood. In this study, anti‐proliferative and anti‐migratory effects of BTZ on PASMCs were first examined by different inducers such as fetal bovine serum (FBS), angiotensin II (Ang II) and platelet‐derived growth factor (PDGF)‐BB, while potential mechanisms including cellular reactive oxygen species (ROS) and mitochondrial ROS were then investigated; finally, signal transduction of ERK and Akt was examined. Our results showed that BTZ attenuated FBS‐, Ang II‐ and PDGF‐BB‐induced proliferation and migration, with associated decreased cellular ROS production and mitochondrial ROS production. In addition, the phosphorylation of ERK and Akt induced by Ang II and PDGF‐BB was also inhibited by BTZ treatment. This study indicates that BTZ can prevent proliferation and migration of PASMCs, which are possibly mediated by decreased ROS production and down‐regulation of ERK and Akt. Thus, proteasome inhibition can be a novel pharmacological target in the management of PAH. [ABSTRACT FROM AUTHOR]

The proteasome inhibitor bortezomib (BTZ) is the first‐line therapy for multiple myeloma (MM). BTZ resistance largely limits its clinical application in MM. Interleukin‐33 (IL‐33) exerts antitumor effects through various mechanisms, including enhancing antitumor immunity and promoting the apoptosis of cancer cells. Here, the synergistic anti‐MM effect of IL‐33 and BTZ was verified, and the underlying mechanisms were elucidated. Bioinformatic analysis indicated that IL‐33 expression levels were downregulated in MM, and that BTZ‐treated MM patients with high IL‐33 levels had better prognosis than those with low IL‐33 levels. Moreover, the patients with high IL‐33 levels had a better treatment response to BTZ. Further immune analysis suggested that IL‐33 can enhance the anti‐MM immunity. IL‐33 and BTZ synergistically inhibited proliferation and induced apoptosis of MM cells, which was mediated by the excessive accumulation of cellular reactive oxygen species (ROS). Furthermore, increased ROS hindered the nuclear translocation of NF‐κB‐p65, thereby decreasing the transcription of target stemness‐related genes (SOX2, MYC, and OCT3/4). These effects induced by the combination therapy could be reversed by eliminating ROS by N‐acetylcysteine. In conclusion, our results indicated that IL‐33 enhanced the sensitivity of MM to BTZ through ROS‐mediated inhibition of nuclear factor kappa‐B (NF‐κB) signal and stemness properties. [ABSTRACT FROM AUTHOR]

Histone H1 is involved in chromatin compaction and dynamics. In human cells, the H1 complement is formed by different amounts of somatic H1 subtypes, H1.0‐H1.5 and H1X. The amount of each variant depends on the cell type, the cell cycle phase, and the time of development and can be altered in disease. However, the mechanisms regulating H1 protein levels have not been described. We have analyzed the contribution of the proteasome to the degradation of H1 subtypes in human cells using two different inhibitors: MG132 and bortezomib. H1 subtypes accumulate upon treatment with both drugs, indicating that the proteasome is involved in the regulation of H1 protein levels. Proteasome inhibition caused a global increase in cytoplasmatic H1, with slight changes in the composition of H1 bound to chromatin and chromatin accessibility and no alterations in the nucleosome repeat length. The analysis of the proteasome degradation pathway showed that H1 degradation is ubiquitin‐independent. The whole protein and its C‐terminal domain can be degraded directly by the 20S proteasome in vitro. Partial depletion of PA28γ revealed that this regulatory subunit contributes to H1 degradation within the cell. Our study shows that histone H1 protein levels are under tight regulation to prevent its accumulation in the nucleus. We revealed a new regulatory mechanism for histone H1 degradation, where the C‐terminal disordered domain is responsible for its targeting and degradation by the 20S proteasome, a process enhanced by the regulatory subunit PA28γ. [ABSTRACT FROM AUTHOR]

For years, proteasomal degradation was predominantly attributed to the ubiquitin-26S proteasome pathway. However, it is now evident that the core 20S proteasome can independently target proteins for degradation. With approximately half of the cellular proteasomes comprising free 20S complexes, this degradation mechanism is not rare. Identifying 20S-specific substrates is challenging due to the dual-targeting of some proteins to either 20S or 26S proteasomes and the non-specificity of proteasome inhibitors. Consequently, knowledge of 20S proteasome substrates relies on limited hypothesis-driven studies. To comprehensively explore 20S proteasome substrates, we employed advanced mass spectrometry, along with biochemical and cellular analyses. This systematic approach revealed hundreds of 20S proteasome substrates, including proteins undergoing specific N- or C-terminal cleavage, possibly for regulation. Notably, these substrates were enriched in RNA- and DNA-binding proteins with intrinsically disordered regions, often found in the nucleus and stress granules. Under cellular stress, we observed reduced proteolytic activity in oxidized proteasomes, with oxidized protein substrates exhibiting higher structural disorder compared to unmodified proteins. Overall, our study illuminates the nature of 20S substrates, offering crucial insights into 20S proteasome biology. Synopsis: A systematic investigation of the repertoire of protein substrates degraded by the 20S proteasome under basal and oxidized conditions reveals hundreds of substrates and differential functionality of naïve and oxidized 20S proteasome complexes. 20S proteasome substrates are primarily RNA- and DNA-binding proteins with intrinsically disordered regions. The 20S proteasome not only fully degrades substrates but also cleaves proteins at their N- and C-termini, indicating regulatory actions. Oxidized proteasomes show lower proteolytic activity in comparison to naïve proteasomes. Oxidized protein substrates display higher structural disorder than naïve substrates. A systematic investigation of the repertoire of protein substrates degraded by the 20S proteasome under basal and oxidized conditions reveals hundreds of substrates and differential functionality of naïve and oxidized 20S proteasome complexes. [ABSTRACT FROM AUTHOR]

Multiple myeloma (MM) is a common hematological malignancy, and patients with MM are recommended to take immunomodulatory drugs such as lenalidomide along with proteasome inhibitors such as bortezomib to extend survival. However, drug resistance influences the efficacy of treatment for MM. In our study, we found that metformin and chidamide both suppressed MM cell growth in a concentration‐ and time‐dependent way (p <.001). Moreover, combined therapy with metformin and chidamide exhibited enhanced inhibition of the growth of MM cells compared with monotherapy (p <.05). Additionally, the triple‐drug combination of metformin and chidamide with lenalidomide or bortezomib was used to stimulate the MM cells, and the results revealed that metformin and chidamide treatment sensitized MM cells to lenalidomide and bortezomib. As a result, the apoptosis (p <.001) together with cell cycle arrest at G0/G1 phase (p <.05) was stimulated by lenalidomide and bortezomib, and showed significant elevation in the triple‐drug combination group compared with the lenalidomide or bortezomib treatment alone group (p <.05). Furthermore, the impacts of different drugs on glycolysis in MM cells were examined. We found that metformin and chidamide combined treatment significantly promoted glucose uptake and reduced energy production in MM cells treated with lenalidomide and bortezomib (p <.001), suggesting that metformin and chidamide affected glycolysis in MM cells and enhanced the sensitivity of lenalidomide and bortezomib in MM by regulating glucose metabolism. In conclusion, metformin and chidamide synergistically hindered MM cell growth and sensitized cells to lenalidomide/bortezomib. The findings of this study might provide novel clues to improve MM therapy. [ABSTRACT FROM AUTHOR]

The standard treatment for canine lymphoma is the CHOP chemotherapy regimen. Proteasome inhibitors have been employed with CHOP for the treatment of human haematological malignancies but remain to be fully explored in canine lymphoma. We identified an association between poor response to CHOP chemotherapy and high mRNA expression levels of proteasomal subunits in a cohort of 15 canine lymphoma patients, and sought to determine the effect of proteasome inhibitors on the viability of a canine B‐cell lymphoma cell line (CLBL‐1). The aim of this study was to investigate whether proteasome inhibitors sensitize these cells to the CHOP agents doxorubicin, vincristine and cyclophosphamide (as 4‐hydroxycyclophosphamide/4‐HC). CLBL‐1 cells were sensitive to proteasome inhibition by bortezomib and ixazomib. The IC50 of bortezomib was 15.1 nM and of ixazomib was 59.14 nM. Proteasome inhibitors plus doxorubicin had a synergistic effect on CLBL‐1 viability; proteosome inhibitors plus vincristine showed different effects depending on the combination ratio, and there was an antagonistic effect with 4‐HC. These results may have clinical utility, as proteasome inhibition could potentially be used with a synergizing CHOP compound to improve responsiveness to chemotherapy for canine lymphoma patients. [ABSTRACT FROM AUTHOR]

Photolipids have emerged as attractive tools for the optical control of lipid functions. They often contain an azobenzene photoswitch that imparts a cis double‐bond upon irradiation. Herein, we present the application of photoswitching to a lipidated natural product, the potent proteasome inhibitor cepafungin I. Several azobenzene‐containing lipids were attached to the cyclopeptide core, yielding photoswitchable derivatives. Most notably, PhotoCep4 exhibited a 10‐fold higher cellular potency in its light‐induced cis‐form, matching the potency of natural cepafungin I. The length of the photolipid tail and distal positioning of the azobenzene photoswitch with respect to the macrocycle is critical for this activity. In a proteome‐wide experiment, light‐triggered PhotoCep4 modulation showed high overlap with constitutively active cepafungin I. The mode of action was studied using crystallography and revealed an identical binding of the cyclopeptide in comparison to cepafungin I, suggesting that differences in their cellular activity originate from switching the tail structure. The photopharmacological approach described herein could be applicable to many other natural products as lipid conjugation is common and often necessary for potent activity. Such lipids are often introduced late in synthetic routes, enabling facile chemical modifications. [ABSTRACT FROM AUTHOR]

Summary: Immune thrombotic thrombocytopenic purpura (iTTP) is a rare and life‐threatening haematological condition. Initial treatment involves plasma exchange (PLEX), corticosteroids, caplacizumab and rituximab. In relapsed and refractory cases despite initial treatments, further immune‐modulating therapy includes the proteasome inhibitor, bortezomib. Evidence for bortezomib in this setting is limited to case reports and case series. We report our experience and perform a systematic review of the literature. We identified 21 publications with 28 unique patients in addition to our cohort of eight patients treated with bortezomib. The median age of patients was 44 years (IQR: 27–53) and 69% female. They were usually in an initial, refractory presentation of iTTP where they had received PLEX, corticosteroids, rituximab and another line of therapy. After bortezomib administration, 72% of patients had a complete response, with 85% maintaining a durable response without relapse at the last follow‐up. [ABSTRACT FROM AUTHOR]

Background: Desensitization is one of the strategies to reduce antibodies and facilitate heart transplantation in highly sensitized patients. We describe our center's desensitization experience with combination of plasma cell (PC) depletion therapy (with proteasome inhibitor or daratumumab) and costimulation blockade (with belatacept). Methods: We reviewed five highly sensitized patients who underwent desensitization therapy with plasma cell depletion and costimulation blockade. We evaluated the response to therapy by measuring the changes in cPRA, average MFI, and number of positive beads > 5000MFI. Results: Five patients, mean age of 56 (37‐66) years with average cPRA of 98% at 5000 MFI underwent desensitization therapy. After desensitization, mean cPRA decreased from 98% to 70% (p =.09), average number of beads > 5000 MFI decreased from 59 to 37 (p =.15), and average MFI of beads > 5000 MFI decreased from 16713 to 13074 (p =.26). Conclusion: Combined PC depletion and CoB could be a reasonable strategy for sustained reduction in antibodies in highly sensitized patients being listed for heart transplantation. [ABSTRACT FROM AUTHOR]

The hydrogen peroxide (H2O2)‐producing NADPH oxidase Nox4, forming a heterodimer with p22phox, is expressed in a variety of cells including those in the heart to mediate adaptive responses to cellular stresses such as hypoxia. Since Nox4 is constitutively active, H2O2 production is controlled by its protein abundance. Hypoxia‐induced Nox4 expression is observed in various types of cells and generally thought to be regulated at the transcriptional level. Here we show that hypoxia upregulates the Nox4 protein level and Nox4‐catalyzed H2O2 production without increasing the Nox4 mRNA in rat H9c2 cardiomyocytes. In these cells, the Nox4 protein is stabilized under hypoxic conditions in a manner dependent on the presence of p22phox. Cell treatment with the proteasome inhibitor MG132 results in a marked decrease of the Nox4 protein under both normoxic and hypoxic conditions, indicating that the proteasome pathway does not play a major role in Nox4 degradation. The decrease is partially restored by the autophagy inhibitor 3‐methyladenine. Furthermore, the Nox4 protein level is upregulated by the lysosome inhibitors bafilomycin A1 and chloroquine. Thus, in cardiomyocytes, Nox4 appears to be degraded via an autophagy‐related pathway, and its suppression by hypoxia likely stabilizes Nox4, leading to upregulation of Nox4‐catalyzed H2O2 production. [ABSTRACT FROM AUTHOR]

Summary: Very scarce data exist about outcomes of relapsed multiple myeloma patients who have failed proteasome inhibitor, immunomodulatory drug, anti‐CD38 monoclonal antibody and therapies targeting B‐cell maturation antigen (BCMA) (Quad‐class exposed [QCE]). In this retrospective single‐centre study, we determined progression‐free survival (PFS) and overall survival (OS) from anti‐BCMA failure in 45 QCE patients. Seven (16%) patients received antibody‐drug conjugate, 20 (44%) bispecific antibodies and 18 (40%) CAR‐T cell. Thirty patients (67%) received ≥1 subsequent line of treatment. PFS was 4.4 months (95% CI = 2.4–12.5) and OS 6.3 months (95% CI = 3.9–14.4). Having an adverse prognosis, QCE myeloma patients remain an unmet medical need. [ABSTRACT FROM AUTHOR]

Background: The use of bortezomib which is a proteasome inhibitor has been demonstrated to be efficacious in small number of patients as a desensitization strategy in heart transplant. We reviewed our single center's experience using Bortezomib along with plasmapheresis as desensitization therapy for highly sensitized patients to assess pre‐ and post‐transplant outcomes. Method: We assessed 43 highly sensitized patients awaiting HTx (defined as cPRA > 50%) between 2010 and 2021 who underwent desensitization therapy with bortezomib. Only those patients who subsequently underwent HTx were included in this study. Enrolled patients received up to four doses of bortezomib (1.3 mg/m2) over 2 weeks in conjunction with plasmapheresis. The efficacy of PP/BTZ was assessed by comparing the calculated panel reactive antibodies to HLA class I or class II antigens. Post‐transplant outcomes including overall survival and incidence of rejection were compared to those of non‐sensitized patients (PRA < 10%, n = 649) from the same center. Results: The average cPRA prior to PP/BTZ was 94.5%. Post‐PP/BTZ there was no statistically significant decline in mean cPRA, class I cPRA, or class II cPRA, though the average percentage decrease in class I cPRA (8.7 ± 17.0%) was higher than the change in class II cPRA (4.4 ± 13.3%). Resulted were also replicated with C1q‐binding antibodies showing more effect on I class compared to class II (15.0 ± 37.4% vs. 6.8 ± 33.6%) as well as with 1:8 dilutional assay (14.0 ± 23.0% vs. 9.1 ± 34.9%). Additionally, PP/BTZ treated patients and the control group of non‐sensitized patients had similar overall 1 year survival (95.4 vs. 92.5%) but patients with PP/BTZ had increased incidence of AMR (79.1% vs. 97.1%, p = <.001), any treated rejection (62.8% vs. 86.7%, p = <.001) and de novo DSA development (81.4% vs. 92.5%, p =.007). Major side effects of PP/BTZ included thrombocytopenia (42%), infection requiring antibiotics (28%), and neuropathy (12%). Conclusion: The use of bortezomib in highly sensitized patients does not significantly lower circulating antibodies prior to heart transplantation. However, its use may improve the chances of obtaining an immuno‐compatible donor heart and contribute to acceptable post‐transplant outcomes. [ABSTRACT FROM AUTHOR]

In this project, we describe proteasome inhibitor (PI) treatment of antibody‐mediated rejection (AMR) in heart transplantation (HTX). From January 2018 to September 2021, 10 patients were treated with PI for AMR: carfilzomib (CFZ) n = 8; bortezomib (BTZ) n = 2. Patients received 1–3 cycles of PI. All patients had ≥1 strong donor‐specific antibody (DSA) (mean fluorescence intensity [MFI] > 8000) in undiluted serum. Most DSAs (20/21) had HLA class II specificity. The MFI of strong DSAs had a median reduction of 56% (IQR = 13%–89%) in undiluted serum and 92% (IQR = 53%–95%) at 1:16 dilution. Seventeen DSAs in seven patients were reduced > 50% at 1:16 dilution after treatment. Four DSAs from three patients did not respond. DSA with MFI > 8000 at 1:16 dilution was less responsive to treatment. 60% (6/10) patients presented with graft dysfunction; 4/6 recovered ejection fraction > 40% after treatment. Pathologic AMR was resolved in 5/7 (71.4%) of patients within 1 year after treatment. 9/10 (90%) patients survived to 1 year after AMR diagnosis. Using PI in AMR resulted in significant DSA reduction with some resolution of graft dysfunction. Larger studies are needed to evaluate PI for AMR. [ABSTRACT FROM AUTHOR]

SIRT4, together with SIRT3 and SIRT5, comprises the mitochondrially localized subgroup of sirtuins. SIRT4 regulates mitochondrial bioenergetics, dynamics (mitochondrial fusion), and quality control (mitophagy) via its NAD+‐dependent enzymatic activities. Here, we address the regulation of SIRT4 itself by characterizing its protein stability and degradation upon CoCl2‐induced pseudohypoxic stress that typically triggers mitophagy. Interestingly, we observed that of the mitochondrial sirtuins, only the protein levels of SIRT4 or ectopically expressed SIRT4‐eGFP decrease upon CoCl2 treatment of HEK293 cells. Co‐treatment with BafA1, an inhibitor of autophagosome–lysosome fusion required for autophagy/mitophagy, or the use of the proteasome inhibitor MG132, prevented CoCl2‐induced SIRT4 downregulation. Consistent with the proteasomal degradation of SIRT4, the lysine mutants SIRT4(K78R) and SIRT4(K299R) showed significantly reduced polyubiquitination upon CoCl2 treatment and were more resistant to pseudohypoxia‐induced degradation as compared to SIRT4. Moreover, SIRT4(K78R) and SIRT4(K299R) displayed increased basal protein stability as compared to wild‐type SIRT4 when subjected to MG132 treatment or cycloheximide (CHX) chase assays. Thus, our data indicate that stress‐induced protein degradation of SIRT4 occurs through two mechanisms: (a) via mitochondrial autophagy/mitophagy, and (b) as a separate process via proteasomal degradation within the cytoplasm. [ABSTRACT FROM AUTHOR]

Despite enormous advances in terms of therapeutic strategies, multiple myeloma (MM) still remains an incurable disease with MM patients often becoming resistant to standard treatments. To date, multiple combined and targeted therapies have proven to be more beneficial compared to monotherapy approaches, leading to a decrease in drug resistance and an improvement in median overall survival in patients. Moreover, recent breakthroughs highlighted the relevant role of histone deacetylases (HDACs) in cancer treatment, including MM. Thus, the simultaneous use of HDAC inhibitors with other conventional regimens, such as proteasome inhibitors, is of interest in the field. In this review, we provide a general overview of HDAC‐based combination treatments in MM, through a critical presentation of publications from the past few decades related to in vitro and in vivo studies, as well as clinical trials. Furthermore, we discuss the recent introduction of dual‐inhibitor entities that could have the same beneficial effects as drug combinations with the advantage of having two or more pharmacophores in one molecular structure. These findings could represent a starting‐point for both reducing therapeutic doses and lowering the risk of developing drug resistance. [ABSTRACT FROM AUTHOR]

Background and Aims: Nonsmall cell lung cancer accounts for over 85% of lung cancer incidences worldwide, and often has a poor prognosis. Proteasome inhibitors, such as bortezomib, have previously demonstrated evidence in preclinical and clinical models in the treatment of NSCLC both alone and as part of chemotherapeutic regimens. Methods: Five databases were searched from inception to February 2023 to identify published clinical trial data and ongoing clinical trials on the use of proteasome inhibitors in treatment of NSCLC with a comprehensive search strategy. Results: This review examines the clinical evidence from 21 completed and published phase I and II trials studying the use of bortezomib monotherapy and combination therapy in the treatment of NSCLC. Bortezomib/docetaxel combination resulted in longer median time‐to‐progression (TTP), median duration of response, median duration of disease control and median progression‐free survival (PFS) than bortezomib monotherapy, with concurrent administration having greater 6‐month PFS and median overall survival (OS) than sequential administration. Bortezomib/vorinostat with chemotherapy was well tolerated and effective. Bortezomib/gemcitabine/carboplatin, bortezomib/bevacizumab/carboplatin and bortezomib/paclitaxel/carboplatin combinations showed promising results and were of further investigational value. Conclusion: Bortezomib showed some clinical promise in combination therapy but not monotherapy. It also demonstrated a manageable side effect profile. Combination regimens are of further investigation value in Phase II trials. [ABSTRACT FROM AUTHOR]

Daratumumab demonstrates activity as a single agent and in combination with either immunomodulatory agents (IMiDs) or proteasome inhibitors (PIs) in relapsed refractory multiple myeloma (RRMM). However, little is known about the benefit of daratumumab retreatment in daratumumab‐refractory MM. This study aimed to analyze the clinical efficacy of daratumumab‐based retreatment (D2) in patients who are daratumumab refractory MM. Retrospectively, we identified 43 RRMM patients from a single‐center database review. The median age was 65 years, 42% patients had high‐risk cytogenetics, and 23% had an extramedullary disease, while the median time between D2 and prior daratumumab was 1 (0.25–39) month. All D2 patients received combination therapy with either pomalidomide, carfilzomib, bortezomib, or lenalidomide. The response rate, median progression‐free, and overall survival were 49%, 7.97 and 32.6 months, respectively. Our study raises the possibility of re‐utilizing daratumumab in combination with different classes of anti‐myeloma drugs to generate responses in RRMM patients who are daratumumab‐refractory. [ABSTRACT FROM AUTHOR]

A series of novel noncovalent glycine/β‐alanine anilide derivatives possessing 2‐chloronaphthoquinone structure as a pharmacophoric unit were designed, synthesized, and evaluated for their antiproliferative and antiproteasomal activities against MCF‐7 cell line, in vitro. According to biological activity results, all the target compounds showed antiproliferative activity in the range of IC50 = 7.10 ± 0.10–41.08 ± 0.14 μM and most of them exhibited inhibitory efficacy with varying ratios against the three catalytic subunits (β1, β2, and β5) presenting caspase‐like (C‐L), trypsin‐like (T‐L) and chymotrypsin‐like (ChT‐L) activities of proteasome. The antiproteasomal activity evaluations revealed that compounds preferentially inhibited the β5 subunit compared with β1 and β2 subunits of the proteasome. Among the compounds, compounds 7 and 9 showed the highest antiproliferative activity with an IC50 value of 7.10 ± 0.10 and 7.43 ± 0.25 μM, respectively. Additionally, compound 7 displayed comparable potency to PI‐083 lead compound in terms of β5 antiproteasomal activity with an inhibition percentage of 34.67 at 10 μM. This compound showed an IC50 value of 32.30 ± 0.45 μM against β5 subunit. Furthermore, molecular modeling studies of the most active compound 7 revealed key interactions with β5 subunit. The results suggest that this class of compounds may be beneficial for the development of new potent proteasome inhibitors. [ABSTRACT FROM AUTHOR]

Introduction: To review the pathogenesis and treatment of multiple myeloma (MM). MM is a hematological malignancy with abnormal plasma cell proliferation in bone marrow. Due to the emergence of drug resistance, MM is still an incurable malignancy, which requires further exploration of pathogenesis and effective therapeutic targets. Methods: In this paper, the method of literature review is adopted to obtain the information about MM. Based on the literature, comprehensive and systematic review is made. Results: MM is a complex pathophysiological process with great heterogeneity, mainly reflected in genomic instability and bone marrow microenvironment. At present, the treatment of MM has made great progress, proteasome inhibitors and immunomodulatory drugs are widely used in clinic. Allogeneic stem cell transplantation may be the only promising cure for MM, and its high transplant‐related mortality limits its clinical application. Conclusions: The future of MM treatment lies in the development of more targeted therapies, novel immunotherapies, and a better understanding of the disease's molecular and genetic basis. [ABSTRACT FROM AUTHOR]

Background: Proteasome inhibitors are in use in treating certain types of cancers. These drugs inhibit the catalytic activity of the 20S proteasome, shared by all the different proteasome complexes. Inhibitors of the 26S‐associated deubiquitinating activity explicitly inhibit the 26S proteasomal degradation of ubiquitinylated substrates. We have previously reported an alternative strategy that is based on reducing the 26S/20S ratio by depleting PSMD1, 6, and 11, the subunits of the 19S proteasome regulatory complex. Given the addiction of the many cancer types to a high 26S/20S ratio, the depletion strategy is highly effective in killing many aggressive cancer cell lines but not mouse and human immortalized and normal cells. Methods: We used two aggressive cell lines, MDA‐MB‐231, a triple‐negative breast tumor cell line, and OVCAR8, a high‐grade ovary adenocarcinoma. Cell culture, mouse MDA‐MB‐231, OVCAR8 xenografts, and patient‐derived ovarian cancer xenograft (PDX) models were transduced with lentivectors expressing PSMD1 shRNA. Tumor size was measured to follow treatment efficacy. Results: Using different experimental strategies of expressing shRNA, we found that PSMD1 depletion, either by expressing PSMD1 shRNA in an inducible manner or in a constitutive manner, robustly inhibited MDA‐MB‐231, and OVCAR8 xenograft tumor growth. Furthermore, the PSMD1 depletion strategy compromised the growth of the PDX of primary ovarian cancer. Conclusion: Our results suggest that reducing the 26S/20S ratio might be a valuable strategy for treating drug‐resistant aggressive types of cancers. [ABSTRACT FROM AUTHOR]

Background: Multiple myeloma (MM) is a hematopoietic malignancy for which proteasome inhibitors have become available in recent years. However, many patients develop resistance to these drugs during treatment. Therefore, it is important to elucidate the mechanisms underlying resistance acquisition by proteasome inhibitors. Side population (SP) cells, which have a high drug efflux capacity and hypoxic responses in the microenvironment have both provided important insights into drug resistance in MM; however, little is known about the characteristics of SP cells in hypoxic microenvironments. Methods: We performed cDNA microarray analysis for SP and non‐SP obtained from RPMI‐8226 and KMS‐11 cell lines cultured for 48 h in normoxic and hypoxic conditions (1% O2). Genes specifically upregulated in hypoxic SP were examined. Results: Our comprehensive gene expression analysis identified HMOX1, BACH2, and DUX4 as protein‐coding genes that are specifically highly expressed in SP cells under hypoxic conditions. We have shown that HMOX1/heme oxygenase‐1 (HMOX1/HO‐1) is induced by hypoxia‐inducible reactive oxygen species (ROS) and reduces ROS levels. Furthermore, we found that HMOX1 contributes to hypoxia‐induced resistance to proteasome inhibitors in vitro and in vivo. Excessive ROS levels synergistically enhance bortezomib sensitivity. In clinical datasets, HMOX1 had a strong and significantly positive correlation with MAFB but not MAF. Interestingly, hypoxic stimulation increased MAFB/MafB expression in myeloma cells; in addition, the knockdown of MAFB under hypoxic conditions suppressed HMOX1 expression. Conclusion: These results suggest that the hypoxia‐ROS‐HMOX1 axis and hypoxia‐induced MafB may be important mechanisms of proteasome inhibitor resistance in hypoxic microenvironments. [ABSTRACT FROM AUTHOR]

Here, we present remarkable epoxyketone‐based proteasome inhibitors with low nanomolar in vitro potency for blood‐stage Plasmodium falciparum and low cytotoxicity for human cells. Our best compound has more than 2,000‐fold greater selectivity for erythrocytic‐stage P. falciparum over HepG2 and H460 cells, which is largely driven by the accommodation of the parasite proteasome for a D‐amino acid in the P3 position and the preference for a difluorobenzyl group in the P1 position. We isolated the proteasome from P. falciparum cell extracts and determined that the best compound is 171‐fold more potent at inhibiting the β5 subunit of P. falciparum proteasome when compared to the same subunit of the human constitutive proteasome. These compounds also significantly reduce parasitemia in a P. berghei mouse infection model and prolong survival of animals by an average of 6 days. The current epoxyketone inhibitors are ideal starting compounds for orally bioavailable anti‐malarial drugs. [ABSTRACT FROM AUTHOR]

Metabolic changes of malignant plasma cells (PCs) and adaptation to tumour microenvironment represent one of the hallmarks of multiple myeloma (MM). We previously showed that MM mesenchymal stromal cells are more glycolytic and produce more lactate than healthy counterpart. Hence, we aimed to explore the impact of high lactate concentration on metabolism of tumour PCs and its impact on the efficacy of proteasome inhibitors (PIs). Lactate concentration was performed by colorimetric assay on MM patient's sera. The metabolism of MM cell treated with lactate was assessed by seahorse and real time Polymerase Chain Reaction (PCR). Cytometry was used to evaluate mitochondrial reactive oxygen species (mROS), apoptosis and mitochondrial depolarization. Lactate concentration resulted increased in MM patient's sera. Therefore, PCs were treated with lactate and we observed an increase of oxidative phosphorylation‐related genes, mROS and oxygen consumption rate. Lactate supplementation exhibited a significant reduction in cell proliferation and less responsive to PIs. These data were confirmed by pharmacological inhibition of monocarboxylate transporter 1 (MCT1) by AZD3965 which was able to overcame metabolic protective effect of lactate against PIs. Consistently, high levels of circulating lactate caused expansion of Treg and monocytic myeloid derived suppressor cells and such effect was significantly reduced by AZD3965. Overall, these findings showed that targeting lactate trafficking in TME inhibits metabolic rewiring of tumour PCs, lactate‐dependent immune evasion and thus improving therapy efficacy. [ABSTRACT FROM AUTHOR]

Triple‐negative breast cancer (TNBC) is an aggressive breast cancer subtype, which has poor prognosis due to the lack of effective targeted drugs. KPT‐330, an inhibitor of the nuclear export protein CRM‐1, has been widely used in clinical medicine. Y219, a novel proteasome inhibitor designed by our group, shows superior efficacy, reduced toxicity, and reduced off‐target effects as compared to the proteasome inhibitor bortezomib. In this study, we investigated the synergistic effect of KPT‐330 and Y219 against TNBC cells, as well as the underlying mechanisms. We report that combination treatment with KPT‐330 and Y219 synergistically inhibited the viability of TNBC cells in vitro and in vivo. Further analysis revealed that the combined use of KPT‐330 and Y219 induced G2‐M phase arrest and apoptosis in TNBC cells, and attenuated nuclear factor kappa B (NF‐κB) signaling by facilitating nuclear localization of IκB‐α. Collectively, these results suggest that the combined use of KPT‐330 and Y219 may be an effective therapeutic strategy for the treatment of TNBC. [ABSTRACT FROM AUTHOR]

Aims: Opioid addiction is a major public health issue, yet its underlying mechanism is still unknown. The aim of this study was to explore the roles of ubiquitin–proteasome system (UPS) and regulator of G protein signaling 4 (RGS4) in morphine‐induced behavioral sensitization, a well‐recognized animal model of opioid addiction. Methods: We explored the characteristics of RGS4 protein expression and polyubiquitination in the development of behavioral sensitization induced by a single morphine exposure in rats, and the effect of a selective proteasome inhibitor, lactacystin (LAC), on behavioral sensitization. Results: Polyubiquitination expression was increased in time‐dependent and dose‐related fashions during the development of behavioral sensitization, while RGS4 protein expression was not significantly changed during this phase. Stereotaxic administration of LAC into nucleus accumbens (NAc) core inhibited the establishment of behavioral sensitization. Conclusion: UPS in NAc core is positively involved in behavioral sensitization induced by a single morphine exposure in rats. Polyubiquitination was observed during the development phase of behavioral sensitization, while RGS4 protein expression was not significantly changed, indicating that other members of RGS family might be substrate proteins in UPS‐mediated behavioral sensitization. [ABSTRACT FROM AUTHOR]

The role of the proteasome inhibitor ixazomib in the treatment of POEMS syndrome continues to evolve. He and colleagues present the results of a study investigating ixazomib in combination with cyclophosphamide and dexamethasone in newly diagnosed POEMS patients. The triplet showed excellent efficacy and tolerability, and constitutes an effective treatment option for patients with POEMS. Commentary on: He et al. An open‐label, prospective trial to evaluate the efficacy and safety of ixazomib in combination with cyclophosphamide and dexamethasone in patients with newly‐diagnosed POEMS syndrome. Br J Haematol 2024;205:478‐482. [ABSTRACT FROM AUTHOR]

Background: The use of proteasome inhibitors (PIs), new immune modulators (IMiDs), and other new drugs, as well as high‐dose chemotherapy combined with autologous stem cell transplantation has considerably improved the survival of young patients with multiple myeloma (MM). However, the improvement in survival among elderly patients remains insufficient. Optimal treatment recommendation models for elderly patients with MM have not been developed especially there are quite few study in the real world. Methods: We retrospectively analyzed the treatment patterns and outcomes of 328 Chinese patients (≥65 years) with MM in a real‐world setting. Patients were divided into three groups according to induction regimens. Results: The median age of the cohort was 70 (65–86) years. The patients were divided into group 1 (PIs based regimens, n = 218), group 2 (IMiDs based regimens, n = 48) and group 3 (PIs + IMiDs, n = 62). Induction regimens in group 3 produced higher overall response rate than group 1 and 2 (85.42% vs. 71.08% vs. 66.67%, p = 0.016). The median follow‐up of the cohort was 30 (interquartile range [IQR] 18–36) months. For the entire cohort median progression‐free survival (PFS) was 26 (IQR 12.00–42.89) months and overall survival (OS) was 60 (IQR 40.00–67.20) months. The PFS were not significantly different among the three groups (28 months vs. 18 months vs. 26 months, p = 0.182). So were the OS (60 months vs. 59 months vs. not reached, p = 0.067). Multivariate analysis revealed that age >70 year, frailty status (Geriatric vulnerability score), induction efficacy < partial remission, and no maintenance treatment were independent poor prognostic factors for OS. Conclusion: Front‐line induction regimens combining PIs and IMiDs developed more deep response than single PI or IMiD based regimens. Maintenance treatment can further improve the clinical outcome in elderly MM patients in real‐world setting. [ABSTRACT FROM AUTHOR]

Cystathionine beta‐synthase (CBS)‐deficient homocystinuria (HCU) is the most common inborn error of sulfur amino acid metabolism. The pyridoxine non‐responsive form of the disease manifests itself by massively increasing plasma and tissue concentrations of homocysteine, a toxic intermediate of methionine metabolism that is thought to be the major cause of clinical complications including skeletal deformities, connective tissue defects, thromboembolism and cognitive impairment. The current standard of care involves significant dietary interventions that, despite being effective, often adversely affect quality of life of HCU patients, leading to poor adherence to therapy and inadequate biochemical control with clinical complications. In recent years, the unmet need for better therapeutic options has resulted in development of novel enzyme and gene therapies and exploration of pharmacological approaches to rescue CBS folding defects caused by missense pathogenic mutations. Here, we review scientific evidence and current state of affairs in development of recent approaches to treat HCU. [ABSTRACT FROM AUTHOR]

Ruxolitinib with lenalidomide and dexamethasone shows anti‐myeloma effects in vitro and in vivo. MUC1 leads to lenalidomide resistance in multiple myeloma (MM) cells, and ruxolitinib blocks its expression. Thus, ruxolitinib may restore sensitivity to lenalidomide. A phase I trial was conducted to determine the safety and efficacy of ruxolitinib with lenalidomide and methylprednisolone for patients with relapsed/refractory (RR)MM who had been treated with lenalidomide, steroids and a proteasome inhibitor and showed progressive disease at study entry. A traditional 3 + 3 dose escalation design was used to enroll subjects in four cohorts. Subjects received ruxolitinib twice daily, lenalidomide daily on days 1–21 of a 28 day cycle and methylprednisolone orally every other day. Primary endpoints were safety, clinical benefit rate (CBR) and overall response rate (ORR). Forty‐nine patients were enrolled. The median age was 64 years and they had received a median of six prior treatments including lenalidomide and steroids to which 94% were refractory. No dose limiting toxicities occurred. The CBR and ORR were 49% and 36%, respectively. All responding patients were refractory to lenalidomide. Grade 3 or 4 adverse events (AEs) included anemia (17%), decreased lymphocyte count (15%), and hypophosphatemia (10%). Most common serious AEs included sepsis (9.8%) and pneumonia (7.8%). This Phase I trial demonstrates that a JAK inhibitor, ruxolitinib, can overcome refractoriness to lenalidomide and steroids for patients with RRMM. These results represent a promising novel therapeutic approach for treating MM. NCT03110822. [ABSTRACT FROM AUTHOR]

The treatment scenario for newly‐diagnosed transplant‐ineligible multiple myeloma patients (NEMM) is quickly evolving. Currently, combinations of proteasome inhibitors and/or immunomodulatory drugs +/− the monoclonal antibody Daratumumab are used for first‐line treatment, even if head‐to‐head comparisons are lacking. To compare efficacy and safety of these regimens, we performed a network meta‐analysis of 27 phase 2/3 randomized trials including a total of 12,935 patients and 23 different schedules. Four efficacy/outcome and one safety indicators were extracted and integrated to obtain (for each treatment) the surface under the cumulative ranking‐curve (SUCRA), a metric used to build a ranking chart. With a mean SUCRA of 83.8 and 80.08 respectively, VMP + Daratumumab (DrVMP) and Rd + Daratumumab (DrRd) reached the top of the chart. However, SUCRA is designed to work for single outcomes. To overcome this limitation, we undertook a dimensionality reduction approach through a principal component analysis, that unbiasedly grouped the 23 regimens into three different subgroups. On the bases of our results, we demonstrated that first line treatment for NEMM should be based on DrRd (most active, but continuous treatment), DrVMP (quite "fixed‐time" treatment), or, alternatively, VRD and that, surprisingly, melphalan as well as Rd doublets still deserve a role in this setting. [ABSTRACT FROM AUTHOR]

The ubiquitin–proteasome pathway and its functional interplay with other proteostatic and/or mitostatic modules are crucial for cell viability, especially in post‐mitotic cells like cardiomyocytes, which are constantly exposed to proteotoxic, metabolic, and mechanical stress. Consistently, treatment of multiple myeloma patients with therapeutic proteasome inhibitors may induce cardiac failure; yet the effects promoted by heart‐targeted proteasome dysfunction are not completely understood. We report here that heart‐targeted proteasome knockdown in the fly experimental model results in increased proteome instability and defective mitostasis, leading to disrupted cardiac activity, systemic toxicity, and reduced longevity. These phenotypes were partially rescued by either heart targeted‐ or by dietary restriction‐mediated activation of autophagy. Supportively, activation of autophagy by Rapamycin or Metformin administration in flies treated with proteasome inhibitors reduced proteome instability, partially restored mitochondrial function, mitigated cardiotoxicity, and improved flies' longevity. These findings suggest that autophagic inducers represent a novel promising intervention against proteasome inhibitor‐induced cardiovascular complications. [ABSTRACT FROM AUTHOR]

Summary: For patients with newly diagnosed multiple myeloma, survival outcomes continue to improve significantly: however, nearly all patients will relapse following induction treatment. Optimisation of induction therapy is essential to provide longer term disease control and the current standard of care for most patients incorporates an immunomodulatory agent and proteasome inhibitor, most commonly lenalidomide and bortezomib in combination with dexamethasone (RVD), with maintenance until progression. Historically there has been limited access to RVD as an induction strategy outside of the United States; fortunately, there is now increasing access worldwide. This review discusses the rationale for use of RVD as induction therapy and aims to provide guidance in prescribing this regimen in order to optimise efficacy while minimising the toxicities of treatment. We also highlight the increasing evidence for the utility of addition of a monoclonal antibody to the RVD backbone to deepen responses and potentially provide longer disease control. [ABSTRACT FROM AUTHOR]

Inhibition of IRE1 RNase activity sensitizes patient-derived acute myeloid leukaemia cells to proteasome inhibitors The cells that were most responsive to MKC8866 plus CFZ co-treatment when compared with CFZ treatment alone had the highest XBP1s and vice versa. Significantly increased AML cell death was observed in the combination treatments that included CFZ ( I p i < 0.0001); increased cell death was observed in the combination treatments with BTZ but this was not significant (Figure 1D,E, right panels). We demonstrate that an IRE1 RNase inhibitor (MKC8866), in combination with proteasome inhibitors, significantly decreases XBP1s levels and increases cell death in AML cell lines and patient-derived AML cells. [Extracted from the article]

Background: Maintenance therapy with proteasome inhibitors (PIs) can improve outcomes of multiple myeloma (MM) patients, however, the neurotoxicity and parenteral route of bortezomib limit its long‐term use. An efficacious, tolerable, and convenient PI option is needed. Methods: In this single‐center, real‐world study, we retrospectively analyzed the outcome and safety profile of ixazomib‐based maintenance therapy in patients who plateaued with the responses of steady disease or better after bortezomib‐based induction therapy in MM patients not undergoing transplantation. Results: Of all the 71 patients, 37 cases (52.1%) were newly diagnosed MM (NDMM) and 34 cases (47.9%) were relapsed and/or refractory MM (RRMM). The overall response rate (ORR) was 81.7%, including 34 patients (47.9%) with a very good response rate or better (≥VGPR) after a median of nine cycles (6–14) of bortezomib‐based induction therapy. Then the ORR was transformed to 74.6% including 39 patients of ≥VGPR (54.9%) after a median of six courses (2–25) of ixazomib‐based maintenance therapy. Of these, 18 patients (25.4%) exhibited responses deepened. With 26.5 months median follow‐up, median progression‐free survival (PFS) was 28.4 and 16.5 months from the start of bortezomib and 16.2 and 10.0 months from the initiation of ixazomib in NDMM and RRMM group, respectively. Moreover, responses deepened during the maintenance phase (hazard ratio: 0.270, p = 0.007), and responses of ≥VGPR during the induction phase (hazard ratio: 0.218, p < 0.001) were confirmed to independently predict longer PFS after multivariate analyses. Severe adverse events (grade 3/4) were relatively rare. Bortezomib‐emergent peripheral neuritis (PN) was significantly relived after the transition to ixazomib (p < 0.001). Conclusion: This real‐world analysis has demonstrated oral ixazomib is a favorable option of long‐term administration for maintenance with efficacy and feasibility and confirmed the association between deepening responses with ixazomib and prolonged PFS. [ABSTRACT FROM AUTHOR]

Multiple myeloma (MM) is the second‐ranking malignancy in hematological tumors. The pathogenesis of MM is complex with high heterogeneity, and the development of the disease is a multistep process. Chromosomal translocations, aneuploidy, genetic mutations, and epigenetic aberrations are essential in disease initiation and progression. The correlation between MM cells and the bone marrow microenvironment is associated with the survival, progression, migration, and drug resistance of MM cells. In recent decades, there has been a significant change in the paradigm for the management of MM. With the development of proteasome inhibitors, immunomodulatory drugs, monoclonal antibodies, chimeric antigen receptor T‐cell therapies, and novel agents, the survival of MM patients has been significantly improved. In addition, nanotechnology acts as both a nanocarrier and a treatment tool for MM. The properties and responsive conditions of nanomedicine can be tailored to reach different goals. Nanomedicine with a precise targeting property has offered great potential for drug delivery and assisted in tumor immunotherapy. In this review, we summarize the pathogenesis and current treatment options of MM, then overview recent advances in nanomedicine‐based systems, aiming to provide more insights into the treatment of MM. [ABSTRACT FROM AUTHOR]

We aim to determine the cumulative and comparative risk of cardiovascular events associated with different Immunomodulatory Drugs (iMiDs) and Proteasome Inhibitor (PIs) in Multiple Myeloma (MM) patients through pairwise and network meta‐analysis. Electronic searches were conducted using Ovid MEDLINE, EMBASE, CINAHL, Web of Science, and Clinical Trial Registry (Clinical Trials.gov) up to May 2021. Phase 3 randomized clinical trials (RCTs) reporting cardiotoxicity in MM patients (newly diagnoses and/or relapsed) treated with iMiD and/or PI. Studies, where iMiD or PI was used alongside the chemotherapy versus placebo or no additional drugs (control) in the other arm were included. The primary outcome was the presence of cardiotoxicity after follow‐up. Pairwise meta‐analysis and network meta‐analysis were performed using the frequentist's approach to estimate the odds ratio (OR). Twenty RCTs with 10,373 MM patients were included in this analysis. Eleven studies compared iMiDs with control, seven studies compared PIs with control, and two studies compared bortezomib against carfilzomib. CTACE high‐grade (≥grade 3) cardiotoxic events were increased with iMiDs compared to their control counterpart (OR 2.05; 95% CI 1.30–3.26). Similar high‐grade cardiotoxicity was also noted more frequently with PI use when compared to the control group (OR 1.67; 95% CI 1.17–2.40). Among the PIs, carfilzomib was associated with a maximum risk of cardiotoxicity (OR 2.68; 95% CI 1.63–4.40). There was no evidence of publication bias among studies. iMiDs and PIs, particularly carfilzomib, appear to be associated with increased risk of high‐grade cardiovascular events in MM patients. [ABSTRACT FROM AUTHOR]

Gallbladder cancer (GBC) is a rare but the most malignant type of biliary tract tumor. It is usually diagnosed at an advanced stage and conventional treatments are unsatisfactory. As a proteasome inhibitor, bortezomib (BTZ) exhibits excellent antitumor ability in GBC. However, the long‐term treatment efficacy is limited by its resistance, poor stability, and high toxicity. Herein, BTZ‐encapsulated pH‐responsive copolymeric nanoparticles with estrone (ES‐NP(BTZ; Ce6)) for GBC‐specific targeted therapy is reported. Due to the high estrogen receptor expression in GBC, ES‐NP(BTZ; Ce6) can rapidly enter the cells and accumulate near the nucleus via ES‐mediated endocytosis. Under acidic tumor microenvironment (TME) and 808 nm laser irradiation, BTZ is released and ROS is generated by Ce6 to destroy the "bounce‐back" response pathway proteins, such as DDI2 and p97, which can effectively inhibit proteasomes and increase apoptosis. Compared to the traditional treatment using BTZ monotherapy, ES‐NP(BTZ; Ce6) can significantly impede disease progression at lower BTZ concentrations and improve its resistance. Moreover, ES‐NP(BTZ; Ce6) demonstrates similar antitumor abilities in patient‐derived xenograft animal models and five other types of solid tumor cells, revealing its potential as a broad‐spectrum antitumor formulation. [ABSTRACT FROM AUTHOR]

Background and Purpose: Aberrant lipid metabolism is recognized as a key feature of cancer cells. Our initial research on MS‐based analysis of lipids in a multiple myeloma (MM) cell line showed a significant accumulation of lipids in multiple myeloma cells after proteasome inhibition. This finding prompted us to hypothesize that multiple myeloma cell survival depends on the maximal utilization of abnormally accumulated lipids. Therefore, we explored whether lipid metabolism‐modulating agents would synergize with proteasome inhibitors. Experimental Approach Lipid accumulation in multiple myeloma cells was measured by MS. Synergism between lipid regulators and proteasome inhibitors was assessed by cell viability and apoptosis. A novel stable derivative of fenofibrate (FCE) was synthesized and used to treat multiple myeloma cells in vitro and in vivo along with the proteasome inhibitor ixazomib. ChIP‐seq, western blotting and RT‐qPCR were performed to explore the potential mechanism(s) underlying the increase in lipid levels in multiple myeloma cells after proteasome inhibition. Key Results: Accumulation of lipids in multiple myeloma cells was induced by proteasome inhibition. Lipid‐lowering drugs and MG‐132 exerted a synergistic effect to kill multiple myeloma cells. FCE showed significant synergistic activity in vitro and in vivo with ixazomib. The abnormal lipid accumulation in multiple myeloma cells that was enhanced by proteasome inhibitors might be due to the elevated SREBP1/2 expression induced by ATF4. Conclusions and Implications: Our results provide a proof of principle and support for the further clinical evaluation of the combination of lipid‐modulating drugs with proteasome inhibitors in the treatment of multiple myeloma. [ABSTRACT FROM AUTHOR]

Mantle cell lymphoma (MCL) is a haematologic malignancy. The proteasome inhibitor (PI) bortezomib has been approved to treat MCL, but resistance has emerged through mechanisms that remain unclear. This study aimed to explore the mechanism of PI resistance in MCL and identify new targets for this patient subgroup. Carfilzomib‐resistant (CR) MCL cell lines and primary samples were used for both in vitro and in vivo experiments to identify gene expression and explore their related signalling pathways. We first identified mucin 20 (MUC20) suppression in carfilzomib‐resistant MCL models. MUC20 overexpression sensitized cells to carfilzomib in vitro and in vivo. MUC20 expression was inversely related to activation of c‐Met and the downstream p44/42 MAPK pathway. c‐Met activation with hepatocyte growth factor (HGF) induced PI resistance, while c‐Met inhibition restored PI sensitivity. Carfilzomib resistance and depressed MUC20 expression were associated with enhanced proteasome activity and higher expression of proteassemblin (POMP), a chaperone for catalytically active proteasome assembly. c‐Met and POMP were associated through binding and induction of MAPK‐regulated ELK1 to the POMP promoter. Our data reveal that c‐Met signalling activation enhanced proteasome capacity as a mechanism of PI resistance, and MUC20 expression may be a useful biomarker for PI therapy. [ABSTRACT FROM AUTHOR]

Human cytomegalovirus (HCMV) is a globally ubiquitous pathogen and causes congenital infection as well as opportunistic infection in immunocompromised patients. The HCMV UL42 gene encodes a membrane protein that regulates the function of Nedd4 family ubiquitin E3 ligases through its PPxY motif. As HCMV envelope glycoprotein B (gB) also has a PPxY motif at its C‐terminal cytoplasmic domain, we examined whether there was any relationship between UL42 protein and gB. Among the Nedd4 family proteins, Nedd4, Nedd4L, and Itch induced the degradation of gB in transiently expressing cells. The degradation of gB by Nedd4 was inhibited by proteasome inhibitor MG132, lysosome inhibitor chloroquine, and the co‐expression of UL42 proteins. Among those Nedd4 family proteins, Itch was relocalized by the co‐expression of gB to the perinuclear region of the cytoplasm. A co‐immunoprecipitation assay demonstrated an interaction between gB and Itch through its PPxY motif. The 150 kDa gB precursor was aberrantly ubiquitinated, and the total amount of gB was quickly decreased in the absence of UL42. Our results indicate that UL42 prevents the degradation of gB by the inhibition of Nedd4 family proteins. [ABSTRACT FROM AUTHOR]

For the local treatment of bone defects, highly adaptable macromolecular architectures are still required as drug delivery system (DDS) in solid bone substitute materials. Novel DDS fabricated by host–guest interactions between β‐cyclodextrin‐modified dendritic glycopolymers and adamantane‐modified temperature‐sensitive polymers for the proteasome inhibitor bortezomib (BZM) is presented. These DDS induce a short‐ and long‐term (up to two weeks) retarded release of BZM from calcium phosphate bone cement (CPC) in comparison to a burst release of the drug alone. Different release parameters of BZM/DDS/CPC are evaluated in phosphate buffer at 37 °C to further improve the long‐term retarded release of BZM. This is achieved by increasing the amount of drug (50–100 µg) and/or DDS (100–400 µg) versus CPC (1 g), by adapting the complexes better to the porous bone cement environment, and by applying molar ratios of excess BZM toward DDS with 1:10, 1:25, and 1:100. The temperature‐sensitive polymer shells of BZM/DDS complexes in CPC, which allow drug loading at room temperature but are collapsed at body temperature, support the retarding long‐term release of BZM from DDS/CPC. Thus, the concept of temperature‐sensitive DDS for BZM/DDS complexes in CPC works and matches key points for a local therapy of osteolytic bone lesions. [ABSTRACT FROM AUTHOR]