Toxoplasmic encephalitis with high 201Tl uptake and retention mimicking malignant lymphoma in a patient with human immunodeficiency virus infection.

Various opportunistic infections develop during immunodeficiency due to human immunodeficiency virus (HIV) infection. The treatment options for malignant lymphoma (ML) and toxoplasmic encephalitis (TE) are completely different; therefore, their discrimination is critical. A 25-year-old female of foreign nationality had been experiencing headaches for several weeks and suddenly developed convulsions. Brain computed tomography revealed multiple intracranial lesions; therefore, the patient was referred to the neurosurgery department. Brain magnetic resonance imaging (MRI) revealed multiple masses with surrounding edema, accompanied by enhanced contrast. The largest mass (2 cm) in the left occipital lobe exhibited ringed contrast enhancement. Her blood test results showed a CD4 count of 40/µL, positive HIV Ag/Ab, HIV-RNA level of 56 × 104 copies/mL, positive anti-Toxoplasma IgG (63 IU/mL), and negative anti-Toxoplasma IgM. 201Tl- single photon emission computed tomography (201Tl-SPECT) revealed abnormal accumulation only in the tumor in the left occipital lobe (early T/N ratio, 3.034; delayed T/N ratio, 2.738; retention index, 0.9), which was suspected to be a ML. Both tumors, with or without high accumulation of 201Tl, were subjected to craniotomy biopsy. Pathological examination revealed infiltration of small lymphocytes with a necrotic background. The patient was diagnosed with TE based on a positive result of a tissue polymerase chain reaction test for Toxoplasma gondii. Two weeks after sulfamethoxazole and trimethoprim combination therapy, MRI imaging showed dramatic improvement in multiple brain tumors. This case is atypical because ML was ruled out despite high 201Tl-SPECT uptake and retention. Careful diagnosis through pathological examination and DNA testing is important.

Ex vivo expansion and activation of Vγ9Vδ2 T cells by CELMoDs in combination with zoledronic acid.

As multiple myeloma (MM) progresses, immune effector cells decrease in number and function and become exhausted. This remains an insurmountable clinical issue that must be addressed by development of novel modalities to revitalize anti-MM immunity. Human Vγ9Vδ2 T (Vδ2+ γδ T) cells serve as the first line of defense against pathogens as well as tumors and can be expanded ex vivo from peripheral blood mononuclear cells (PBMCs) upon treatment with amino-bisphosphonates in combination with IL-2. Here, we demonstrated that next-generation immunomodulators called cereblon E3 ligase modulators (CELMoDs), as well as lenalidomide and pomalidomide, expanded Th1-like Vδ2+ γδ T cells from PBMCs in the presence of zoledronic acid (ZA). However, the expansion of Th1-like Vδ2+ γδ T cells by these immunomodulatory drugs was abolished under IL-2 blockade, although IL-2 production was induced in PBMCs. BTN3A1 triggers phosphoantigen presentation to γδ T-cell receptors and is required for γδ T-cell expansion and activation. ZA but not these immunomodulatory drugs upregulated BTN3A1 in monocytes. These results suggest that immunomodulatory drugs and ZA have cooperative roles in expansion of Th1-like Vδ2+ γδ T cells, and provide the important knowledge for clinical application of human Vδ2+ γδ T cells as effector cells.

Skeletal muscle mass during chemotherapy for haematological malignancies: a retrospective study.

OBJECTIVE: This study investigated whether baseline or alteration in muscle mass affects complications during chemotherapy or overall survival (OS) in haematological malignancies. METHODS: Skeletal Muscle Index (SMI) was evaluated by bioimpedance analysis before and after chemotherapy in patients with haematological malignancies, and the association between muscle mass and clinical data was retrospectively analysed. RESULTS: Exactly 104 patients were enrolled, with a mean age of 62.2 years. SMI was 7.85 and 6.08 in male and female patients under 65 years and 7.10 and 5.92 over 65 years, before chemotherapy, respectively. Lower baseline SMI was not correlated with worse OS in total patients (p=0.915). After a median measurement interval of 30 days after chemotherapy (n=67), body weight and SMI decreased by 2.73% and 2.87% (mean), respectively. The decrease in body weight correlated with the loss of trunk muscle mass (R2=0.2107) but was more strongly associated with the loss of lower limbs muscle mass (R2=0.3985). The muscle mass of lower limbs significantly decreased in lymphoma patients who experienced febrile neutropenia (-0.42% vs -6.04%, p=0.040). OS significantly decreased in lymphoma patients with loss of lower limbs muscle ≥2.8% (p=0.0327). CONCLUSIONS: Muscle loss occurred following anticancer treatments, significantly contributing to worse outcomes. Body composition assessment and relevant multimodal prevention of muscle loss may be vital for patients receiving chemotherapy for haematological malignancies.

Acute accumulation of PIM2 and NRF2 and recovery of ß5 subunit activity mitigate multiple myeloma cell susceptibility to proteasome inhibitors.

Resistance to proteasome inhibitors (PIs) has emerged as an important clinical issue. We investigated the mechanisms underlying multiple myeloma (MM) cell resistance to PIs. To mimic their pharmacokinetic/pharmacodynamic (PK/PD) profiles, MM cells were treated with bortezomib and carfilzomib for 1 h at concentrations up to 400 and 1,000 nM, respectively. Susceptibility to these PIs markedly varied among MM cell lines. Pulsatile treatments with PIs suppressed translation, as demonstrated by incorporation of puromycin at 24 h in PI-susceptible MM.1S cells, but not PI-resistant KMS-11 cells. Inhibition of ß5 subunit activity decreased at 24 h in KMS-11 cells, even with the irreversible PI carfilzomib, but not under suppression of protein synthesis with cycloheximide. Furthermore, the proteasome-degradable pro-survival factors PIM2 and NRF2 acutely accumulated in MM cells subjected to pulsatile PI treatments. Accumulated NRF2 was trans-localized into the nucleus to induce the expression of its target gene, HMOX1, in MM cells. PIM and Akt inhibition restored the anti-MM effects of PIs, even against PI-resistant KMS-11 cells. Collectively, these results suggest that increased synthesis of ß5 proteasome subunit and acute accumulation of PIM2 and NRF2 reduce the anti-MM effects of PIs.

Acute suppression of translation by hyperthermia enhances anti-myeloma activity of carfilzomib.

Hyperthermia is a unique treatment option for cancers. Multiple myeloma (MM) remains incurable and innovative therapeutic options are needed. We investigated the efficacy of hyperthermia and carfilzomib in combination against MM cells. Although MM cell lines exhibited different susceptibilities to pulsatile carfilzomib treatment, mild hyperthermia at 43℃ induced MM cell death in all cell lines in a time-dependent manner. Hyperthermia and carfilzomib cooperatively induced MM cell death even under suboptimal conditions. The pro-survival mediators PIM2 and NRF2 accumulated in MM cells due to inhibition of their proteasomal degradation by carfilzomib; however, hyperthermia acutely suppressed translation in parallel with phosphorylation of eIF2α to reduce these proteins in MM cells. Recovery of ß5 subunit enzymatic activity from its immediate inhibition by carfilzomib was observed at 24 h in carfilzomib-insusceptible KMS-11, OPM-2, and RPMI8226 cells, but not in carfilzomib-sensitive MM.1S cells. However, heat treatment suppressed the recovery of ß5 subunit activity in these carfilzomib-insusceptible cells. Therefore, hyperthermia re-sensitized MM cells to carfilzomib. Our results support the treatment of MM with hyperthermia in combination with carfilzomib. Further research is warranted on hyperthermia for drug-resistant extramedullary plasmacytoma.

Therapeutic efficacy of the resorcylic acid lactone LL-Z1640-2 for adult T-cell leukaemia/lymphoma.

Adult T-cell leukaemia/lymphoma (ATL) remains incurable. The NF-κB and interferon regulatory factor 4 (IRF4) signalling pathways are among the critical survival pathways for the progression of ATL. TGF-ß-activated kinase 1 (TAK1), an IκB kinase-activating kinase, triggers the activation of NF-κB. The resorcylic acid lactone LL-Z1640-2 is a potent irreversible inhibitor of TAK1/extracellular signal-regulated kinase 2 (ERK2). We herein examined the therapeutic efficacy of LL-Z1640-2 against ATL. LL-Z1640-2 effectively suppressed the in vivo growth of ATL cells. It induced in vitro apoptosis and inhibited the nuclear translocation of p65/RelA in ATL cells. The knockdown of IRF4 strongly induced ATL cell death while downregulating MYC. LL-Z1640-2 as well as the NF-κB inhibitor BAY11-7082 decreased the expression of IRF4 and MYC at the protein and mRNA levels, indicating the suppression of the NF-κB-IRF4-MYC axis. The treatment with LL-Z1640-2 also mitigated the phosphorylation of p38 MAPK along with the expression of CC chemokine receptor 4. Furthermore, the inhibition of STAT3/5 potentiated the cytotoxic activity of LL-Z1640-2 against IL-2-responsive ATL cells in the presence of IL-2. Therefore, LL-Z1640-2 appears to be an effective treatment for ATL. Further studies are needed to develop more potent compounds that retain the active motifs of LL-Z1640-2.

Myeloma bone disease: pathogenesis and management in the era of new anti-myeloma agents.

INTRODUCTION: Multiple myeloma (MM) is a malignancy of plasma cells with characteristic bone disease. Despite recent great strides achieved in MM treatment owing to the implementation of new anti-MM agents, MM is still incurable and bone destruction remains a serious unmet issue in patients with MM. APPROACH: In this review, we will summarize and discuss the mechanisms of the formation of bone disease in MM and the available preclinical and clinical evidence on the treatment for MM bone disease. CONCLUSIONS: MM cells produce a variety of cytokines to stimulate receptor activator of nuclear factor-κB ligand-mediated osteoclastogenesis and suppress osteoblastic differentiation from bone marrow stromal cells, leading to extensive bone destruction with rapid loss of bone. MM cells alter the microenvironment through bone destruction where they colonize, which in turn favors tumor growth and survival, thereby forming a vicious cycle between tumor progression and bone destruction. Denosumab or zoledronic acid is currently recommended to be administered at the start of treatment in newly diagnosed patients with MM with bone disease. Proteasome inhibitors and the anti-CD38 monoclonal antibody daratumumab have been demonstrated to exert bone-modifying activity in responders. Besides their anti-tumor activity, the effects of new anti-MM agents on bone metabolism should be more precisely analyzed in patients with MM. Because prognosis in patients with MM has been significantly improved owing to the implementation of new agents, the therapeutic impact of bone-modifying agents should be re-estimated in the era of these new agents.

Novel antimyeloma therapeutic option with inhibition of the HDAC1-IRF4 axis and PIM kinase.

Multiple myeloma (MM) preferentially expands and acquires drug resistance in the bone marrow (BM). We herein examined the role of histone deacetylase 1 (HDAC1) in the constitutive activation of the master transcription factor IRF4 and the prosurvival mediator PIM2 kinase in MM cells. The knockdown or inhibition of HDAC1 by the class I HDAC inhibitor MS-275 reduced the basal expression of IRF4 and PIM2 in MM cells. Mechanistically, the inhibition of HDAC1 decreased IRF4 transcription through histone hyperacetylation and inhibiting the recruitment of RNA polymerase II at the IRF4 locus, thereby reducing IRF4-targeting genes, including PIM2. In addition to the transcriptional regulation of PIM2 by the HDAC1-IRF4 axis, PIM2 was markedly upregulated by external stimuli from BM stromal cells and interleukin-6 (IL-6). Upregulated PIM2 contributed to the attenuation of the cytotoxic effects of MS-275. Class I HDAC and PIM kinase inhibitors cooperatively suppressed MM cell growth in the presence of IL-6 and in vivo. Therefore, the present results demonstrate the potential of the simultaneous targeting of the intrinsic HDAC1-IRF4 axis plus externally activated PIM2 as an efficient therapeutic option for MM fostered in the BM.

[Primary cutaneous anaplastic large cell lymphoma with systemic progression responding to low-dose methotrexate therapy].

The standard therapies for primary cutaneous anaplastic large cell lymphoma (pcALCL) in an advanced stage remain undefined. A 71-year-old man presented with multiple erythema and nodules. He was diagnosed with lymphomatoid papulosis (LyP) through a skin biopsy from the left postauricular area. All skin lesions achieved complete response by electron beam irradiation. However, nodular lesions appeared in both inner canthi 5 months later. Histopathological evaluation of the lesional biopsy revealed dominant infiltration of CD30-positive large cells. Positron emission tomography/computed tomography revealed fluorodeoxyglucose-positive cervical and inguinal lymph node swelling and right tonsillitis, followed by the diagnosis of pcALCL and TNM classification T3bN3M0. Since the patient had severe chronic obstructive pulmonary disease and recurrent pneumonia, he received low-dose methotrexate (MTX) (15 mg/week) therapy. Low-dose MTX effectively debulked the lymphadenopathies over time without particular adverse effects. Although the standard therapies for pcALCL are not established, low-dose MTX was effective and considered safe for patients with frailty and compromised respiratory function. Further study is warranted on the pathophysiology of pcALCL after the development of LyP and mechanisms of action of low-dose MTX against LyP and pcALCL.

The importance of retaining physical functions to prevent skeletal-related events in multiple myeloma patients with bone disease.

This study was undertaken to identify baseline conditions and triggering factors for skeletal-related events (SRE) in multiple myeloma (MM) patients treated with denosumab. During the median follow-up of 17 months, SRE occurred in 6 out of 52 newly diagnosed patients and in 5 out of 23 relapsed/refractory patients. Bone fractures occurred by falling down due to orthostatic hypotension and/or muscle weakness in three out of four cases with amyloid light-chain (AL) amyloidosis. A loss of balance and falling down appear to be triggering factors for SRE, especially in frail MM patients with AL amyloidosis, indicating the importance of retaining physical functions to prevent SRE.

A machine learning model using SNPs obtained from a genome-wide association study predicts the onset of vincristine-induced peripheral neuropathy.

Vincristine treatment may cause peripheral neuropathy. In this study, we identified the genes associated with the development of peripheral neuropathy due to vincristine therapy using a genome-wide association study (GWAS) and constructed a predictive model for the development of peripheral neuropathy using genetic information-based machine learning. The study included 72 patients admitted to the Department of Hematology, Tokushima University Hospital, who received vincristine. Of these, 56 were genotyped using the Illumina Asian Screening Array-24 Kit, and a GWAS for the onset of peripheral neuropathy caused by vincristine was conducted. Using Sanger sequencing for 16 validation samples, the top three single nucleotide polymorphisms (SNPs) associated with the onset of peripheral neuropathy were determined. Machine learning was performed using the statistical software R package "caret". The 56 GWAS and 16 validation samples were used as the training and test sets, respectively. Predictive models were constructed using random forest, support vector machine, naive Bayes, and neural network algorithms. According to the GWAS, rs2110179, rs7126100, and rs2076549 were associated with the development of peripheral neuropathy on vincristine administration. Machine learning was performed using these three SNPs to construct a prediction model. A high accuracy of 93.8% was obtained with the support vector machine and neural network using rs2110179 and rs2076549. Thus, peripheral neuropathy development due to vincristine therapy can be effectively predicted by a machine learning prediction model using SNPs associated with it.

Allogeneic haematopoietic stem cell transplantation and patient falls: impact of lower extremity muscle strength.

OBJECTIVES: Patients undergoing allogeneic haematopoietic stem cell transplantation (allo-HSCT) have a higher risk of falls than those receiving other therapies for haematological disorders. This study aimed to investigate the impact of pretransplant lower extremity muscle strength (LEMS) on post-transplant falls. METHODS: In this retrospective cohort study, patients aged ≥18 years who underwent allo-HSCT were included. All data were extracted from medical records. LEMS was defined as the knee extension force measured by a handheld dynamometer divided by the patient's weight. The receiver operating characteristic (ROC) curve was used to calculate the optimal LEMS cut-off value for prediction of falls. Patients were categorised into low and normal LEMS groups based on the cut-off value. The impact of pretransplant LEMS on post-transplant falls was analysed using a Cox proportional hazards model. RESULTS: In total, 101 patients were analysed. During the observation period, falls occurred in 32 patients (31.7%). The ROC curve analysis results showed that the optimal LEMS cut-off value for prediction of falls was 45.4% per body weight. In multivariate analysis, pretransplant low LEMS was a significant predictor of falls in model 1 with patient characteristics as a confounding factor and model 2 with medications-inducing falls as a confounding factor, respectively (model 1: HR 3.23, 95% CI 1.37 to 7.64; model 2: HR 2.82, 95% CI 1.20 to 6.59). CONCLUSIONS: Pretransplant LEMS was a significant predictor of post-transplant falls. The results of this study may help to prevent falls in patients undergoing allo-HSCT.

A Genome-Wide Association Study Predicts the Onset of Dysgeusia Due to Anti-cancer Drug Treatment.

Dysgeusia is a major side effect of anti-cancer drug treatment. Since dysgeusia significantly lowers the patient's QOL, predicting and avoiding its onset in advance is desirable. Accordingly, aims of the present study were to use a genome-wide association study (GWAS) to identify genes associated with the development of dysgeusia in patients taking anti-cancer drugs and to predict the development of dysgeusia using associated single nucleotide polymorphisms (SNPs). GWAS was conducted on 76 patients admitted to the Department of Hematology, Tokushima University Hospital. Using Sanger sequencing for 23 separately collected validation samples, the top two SNPs associated with the development of dysgeusia were determined. GWAS identified rs73049478 and rs41396146 SNPs on the retinoic acid receptor beta (RARB) gene associated with dysgeusia development due to the administration of anti-cancer drugs. Evaluation of the two SNPs using 23 validation samples indicated that the accuracy rate of rs73049478 was relatively high (87.0%). Thus, the findings of the present study suggest that the rs73049478 SNP of RARB can be used to predict the onset of dysgeusia caused by the administration of anti-cancer drugs.

Allogeneic haematopoietic stem cell transplantation-clinical outcomes: impact of leg muscle strength.

OBJECTIVES: Muscle strength decline is reported to predict mortality in many cancers. However, there is little knowledge of the relation between muscle strength decline and clinical outcomes of allogeneic haematopoietic stem cell transplantation (allo-HSCT). This study aimed to determine the impact of pre-transplant lower extremity muscle strength (LEMS) on post-transplant overall survival (OS) and non-relapse mortality (NRM). METHODS: In this retrospective cohort study, 97 adult patients underwent allo-HSCT during 2012-2020. LEMS was defined as knee extension force divided by patient's body weight. The patients were divided into low and high LEMS groups based on pre-transplant LEMS. OS was measured using the Kaplan-Meier method and the Cox proportional hazards model. The cumulative incidence of NRM was evaluated using the Fine and Gray method, with relapse considered as a competing risk event. RESULTS: Probability of OS was significantly lower in the low LEMS groups (HR 2.48, 95% CI 1.20 to 5.12, p=0.014) than in the high LEMS group on multivariate analysis. Five-year OS was 25.8% and 66.4% in the low and high LEMS groups, respectively. Risk of NRM was significantly higher in the low LEMS group (HR 4.49, 95% CI 1.28 to 15.68, p=0.019) than in the high LEMS group. The cumulative incidence of NRM was 41.4% and 11.1% in the low and high LEMS groups, respectively. CONCLUSIONS: Pre-transplant LEMS was a significant factor in predicting OS and NRM.

Robot-assisted total gastrectomy for gastric cancer in a patient with amyotrophic lateral sclerosis receiving long-term tracheostomy invasive ventilation.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease. Although affected patients may develop cancers, major surgical intervention has been hampered by its questionable overall benefit due to limited prognosis and risk of postoperative respiratory collapse. A recent study, however, showed that tracheostomy invasive ventilation (TIV) prolonged median survival to 11.3 years; thus, patients with ALS receiving TIV might benefit from major surgery. A 66-year-old man with ALS, who had received TIV and enteral tube feeding for 8 years, presented with bloody stool. The patient also had type 2 diabetes mellitus, stage 4 chronic kidney disease, abdominal aortic aneurysm, and anti-phospholipid syndrome, as well as multiple episodes of pneumonia and catheter-related urinary tract infection treated by antibiotics. Medical examination and esophagogastroduodenoscopy revealed a type 3 tumor in the middle part of the stomach. The patient's preoperative diagnosis was gastric cancer (GC), MU, type3, Less-Post, T3(SS), N1, H0, P0, M0, cStage III. The estimated mortality rate was 30.5%, according to the Japanese National Clinical Database. The patient and his family were fully informed of the risk of surgery; the patient clearly requested curative surgery by eye movement. Thus, robot-assisted total gastrectomy (RATG) was performed. The tissues were extremely fragile and hemorrhagic. The surgical time was 7 h 0 min; intraoperative blood loss was 324 ml. Pathological examination revealed GC, MU, type3, T4a(SE), N2, H0, CY0, P0, M0 fStage IIIB. The postoperative course was uneventful. He has remained in stable condition for 3 months. Our findings suggest that patients with ALS who achieve longer survival with TIV can undergo major cancer surgery, including robot-assisted surgery, which may facilitate a better mid-long-term prognosis. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13691-021-00499-7.

[Diagnosis of Serous Adenocarcinoma following Pneumatosis Intestinalis Development during Bevacizumab Therapy for Cancer of Unknown Primary-A Case Report].

A 75-year-old woman was treated with TC plus Bev for cancer of unknown primary. During treatment, she presented to the clinic with chief complaints of general malaise and anorexia. On presentation, abdominal distention and upper abdominal tenderness were noted, and sepsis was suspected. A thoracoabdominal CT scan revealed prominent intramural emphysema and mesenteric gas in the ascending colon. An emergency laparotomy was performed for suspected pneumatosis intestinalis non-obstructive intestinal ischemia. However, no intra-abdominal contamination or ischemic changes were observed intraoperatively. Histological examination revealed a small adenocarcinoma on the serous surface of the ascending colon, and immunochemical staining confirmed the diagnosis of serous adenocarcinoma as the patient's primary cancer. This report describes a case in which the patient achieved long-term survival after diagnosis. It also emphasizes the importance of identifying the subset of patients with cancer of unknown primary who have a good prognosis in order to provide appropriate treatment.

Intravenous busulfan-based conditioning with autologous stem cell transplantation for refractory B-cell lymphoma with central nervous system involvement.

The prognosis of relapsed or refractory lymphoma with central nervous system (CNS) involvement remains poor because of the lack of anticancer drugs with sufficient CNS penetration. [Case 1] A 65-year-old man was diagnosed with Stage IV mantle cell lymphoma. After two courses of chemotherapy and autologous hematopoietic stem cell (HSC) collection, urinary retention with fever developed. Cerebrospinal fluid analysis revealed leptomeningeal involvement, which was refractory to high-dose methotrexate therapy. Autologous peripheral blood stem cell transplantation (ASCT) was performed, followed by intravenous busulfan (ivBU), cyclophosphamide, and etoposide ; thereafter, no relapse has been detected for over six years. [Case 2] A 40-year-old woman with right lower hemiplegia was diagnosed with primary CNS lymphoma. Although four courses of high-dose methotrexate therapy were administered, the cerebral tumor increased in size. HSCs were collected after methotrexate therapy, and ASCT was performed in addition to conditioning using ivBU, cyclophosphamide, and etoposide, followed by whole-brain and local boost irradiation. She achieved complete remission, but relapsed two years after ASCT. High-dose ivBU-containing conditioning regimens with ASCT may be useful for refractory B-cell lymphoma with CNS involvement. J. Med. Invest. 68 : 196-201, February, 2021.

Acute Myeloid Leukemia Developing with Acute Pancreatitis Mimicking Autoimmune Pancreatitis.

A 33-year-old man was admitted to our hospital for fever and abdominal pain. A blood analysis revealed pancytopenia and increased serum pancreatic enzymes with disseminated intravascular coagulation. A detailed examination revealed acute pancreatitis, with diffuse swelling of the pancreas and diffuse beaded dilatation of the main pancreatic duct, which mimicked autoimmune pancreatitis complicated by acute myeloid leukemia. Systemic cytotoxic chemotherapy led to the remission of leukemia and pancreatitis. We hypothesized that the etiology of acute pancreatitis was invasion of leukemia cells. Acute pancreatitis is rare as a symptom of leukemia; however, we should consider the possibility of leukemia during the differential diagnosis of acute pancreatitis.

TAK1 is a pivotal therapeutic target for tumor progression and bone destruction in myeloma.

Along with the tumor progression, the bone marrow microenvironment is skewed in multiple myeloma (MM), which underlies the unique pathophysiology of MM and confers aggressiveness and drug resistance in MM cells. TGF-ß-activated kinase-1 (TAK1) mediates a wide range of intracellular signaling pathways. We demonstrate here that TAK1 is constitutively overexpressed and phosphorylated in MM cells, and that TAK1 inhibition suppresses the activation of NF-κB, p38MAPK, ERK and STAT3 to decrease the expression of critical mediators for MM growth and survival, including PIM2, MYC, Mcl-1, IRF4, and Sp1, along with a substantial reduction in the angiogenic factor VEGF in MM cells. Intriguingly, TAK1 phosphorylation was also induced along with upregulation of vascular cell adhesion molecule-1 (VCAM-1) in bone marrow stromal cells (BMSCs) in cocultures with MM cells, which facilitated MM cell-BMSC adhesion while inducing IL-6 production and receptor activator of nuclear factor κ-Β ligand (RANKL) expression by BMSCs. TAK1 inhibition effectively impaired MM cell adhesion to BMSCs to disrupt the support of MM cell growth and survival by BMSCs. Furthermore, TAK1 inhibition suppressed osteoclastogenesis enhanced by RANKL in cocultures of bone marrow cells with MM cells, and restored osteoblastic differentiation suppressed by MM cells or inhibitory factors for osteoblastogenesis overproduced in MM. Finally, treatment with the TAK1 inhibitor LLZ1640-2 markedly suppressed MM tumor growth and prevented bone destruction and loss in mouse MM models. Therefore, TAK1 inhibition may be a promising therapeutic option targeting not only MM cells but also the skewed bone marrow microenvironment in MM.