Serratus Anterior Plane Blocks for Early Rib Fracture Pain Management: The SABRE Randomized Clinical Trial.

Importance: Rib fractures secondary to blunt thoracic trauma typically result in severe pain that is notoriously difficult to manage. The serratus anterior plane block (SAPB) is a regional anesthesia technique that provides analgesia to most of the hemithorax; however, SAPB has limited evidence for analgesic benefits in rib fractures. Objective: To determine whether the addition of an SAPB to protocolized care bundles increases the likelihood of early favorable analgesic outcomes and reduces opioid requirements in patients with rib fractures. Design, Setting, and Participants: This multicenter, open-label, pragmatic randomized clinical trial was conducted at 8 emergency departments across metropolitan and regional New South Wales, Australia, between April 12, 2021, and January 22, 2022. Patients aged 16 years or older with clinically suspected or radiologically proven rib fractures were included in the study. Participants were excluded if they were intubated, transferred for urgent surgical intervention, or had a major concomitant nonthoracic injury. Data were analyzed from September 2022 to July 2023. Interventions: Patients were randomly assigned (1:1) to receive an SAPB in addition to usual rib fracture management or standard care alone. Main Outcomes and Measures: The primary outcome was a composite pain score measured 4 hours after enrollment. Patients met the primary outcome if they had a pain score reduction of 2 or more points and an absolute pain score of less than 4 out of 10 points. Results: A total of 588 patients were screened, of whom 210 patients (median [IQR] age, 71 [55-84] years; 131 [62%] male) were enrolled, with 105 patients randomized to receive an SAPB plus standard care and 105 patients randomized to standard care alone. In the complete-case intention-to-treat primary outcome analysis, the composite pain score outcome was reached in 38 of 92 patients (41%) in the SAPB group and 18 of 92 patients (19.6%) in the control group (relative risk [RR], 0.73; 95% CI, 0.60-0.89; P = .001). There was a clinically significant reduction in overall opioid consumption in the SAPB group compared with the control group (eg, median [IQR] total opioid requirement at 24 hours: 45 [19-118] vs 91 [34-155] milligram morphine equivalents). Rates of pneumonia (6 patients [10%] vs 7 patients [11%]), length of stay (eg, median [IQR] hospital stay, 4.2 [2.2-7.7] vs 5 [3-7.3] days), and 30-day mortality (1 patient [1%] vs 3 patients [4%]) were similar between the SAPB and control groups. Conclusions and Relevance: This randomized clinical trial found that the addition of an SAPB to standard rib fracture care significantly increased the proportion of patients who experienced a meaningful reduction in their pain score while also reducing in-hospital opioid requirements. Trial Registration: http://anzctr.org.au Identifier: ACTRN12621000040864.

Mitochondrial Raf1 Regulates Glutamine Catabolism.

Raf kinases play vital roles in normal mitogenic signaling and cancer, however, the identities of functionally important Raf-proximal proteins throughout the cell are not fully known. Raf1 proximity proteomics/BioID in Raf1-dependent cancer cells unexpectedly identified Raf1-adjacent proteins known to reside in the mitochondrial matrix. Inner-mitochondrial localization of Raf1 was confirmed by mitochondrial purification and super-resolution microscopy. Inside mitochondria, Raf1 associated with glutaminase (GLS) in diverse human cancers and enabled glutaminolysis, an important source of biosynthetic precursors in cancer. These impacts required Raf1 kinase activity and were independent of canonical MAP kinase pathway signaling. Kinase-dead mitochondrial matrix-localized Raf1 impaired glutaminolysis and tumorigenesis in vivo. These data indicate that Raf1 localizes inside mitochondria where it interacts with GLS to engage glutamine catabolism and support tumorigenesis.

Optical and Structural Properties of Aluminum Nitride Epi-Films at Room and High Temperature.

The high-quality aluminum nitride (AlN) epilayer is the key factor that directly affects the performance of semiconductor deep-ultraviolet (DUV) photoelectronic devices. In this work, to investigate the influence of thickness on the quality of the AlN epilayer, two AlN-thick epi-film samples were grown on c-plane sapphire substrates. The optical and structural characteristics of AlN films are meticulously examined by using high-resolution X-ray diffraction (HR-XRD), scanning electron microscopy (SEM), a dual-beam ultraviolet-visible spectrophotometer, and spectroscopic ellipsometry (SE). It has been found that the quality of AlN can be controlled by adjusting the AlN film thickness. The phenomenon, in which the thicker AlNn film exhibits lower dislocations than the thinner one, demonstrates that thick AlN epitaxial samples can work as a strain relief layer and, in the meantime, help significantly bend the dislocations and decrease total dislocation density with the thicker epi-film. The Urbach's binding energy and optical bandgap (Eg) derived by optical transmission (OT) and SE depend on crystallite size, crystalline alignment, and film thickness, which are in good agreement with XRD and SEM results. It is concluded that under the treatment of thickening film, the essence of crystal quality is improved. The bandgap energies of AlN samples obtained from SE possess larger values and higher accuracy than those extracted from OT. The Bose-Einstein relation is used to demonstrate the bandgap variation with temperature, and it is indicated that the thermal stability of bandgap energy can be improved with an increase in film thickness. It is revealed that when the thickness increases to micrometer order, the thickness has little effect on the change of Eg with temperature.

Unraveling the surface proteomic profile of multiple myeloma to reveal new immunotherapeutic targets and markers of drug resistance.

The cell surface proteome ("surfaceome") serves as the interface between diseased cells and their local microenvironment. In cancer, this compartment is critical not only for defining tumor biology but also serves as a rich source of potential therapeutic targets and diagnostic markers. Recently, we profiled the surfaceome of the blood cancer multiple myeloma, an incurable plasma cell malignancy. While available small molecule agents can drive initial remissions in myeloma, resistance inevitably occurs. Several new classes of immunotherapies targeting myeloma surface antigens, including antibody therapeutics and chimeric antigen receptor (CAR) T-cells, can further prolong survival. However, new approaches are still needed for those who relapse. We thus applied the glycoprotein cell surface capture (CSC) methodology to panel of multiple myeloma cell lines, identifying key surface protein features of malignant plasma cells. We characterized the most abundant surface proteins on plasma cells, nominating CD48 as a high-density antigen favorable for a possible avidity-based strategy to enhance CAR-T efficacy. After chronic resistance to proteasome inhibitors, a first-line therapy, we found significant alterations in the surface profile of myeloma cells, including down-regulation of CD50, CD361/EVI2B, and CD53, while resistance to another first-line therapy, lenalidomide, drove increases in CD33 and CD45/PTPRC. In contrast, short-term treatment with lenalidomide led to upregulation of the surface antigen MUC-1, thereby enhancing efficacy of MUC-1 targeting CAR-T cells. Integrating our proteomics data with available transcriptome datasets, we developed a scoring system to rank potential standalone immunotherapy targets. Novel targets of interest included CCR10, TXNDC11, and LILRB4. We developed proof-of-principle CAR-T cells versus CCR10 using its natural ligand, CCL27, as an antigen recognition domain. Finally, we developed a "miniaturized" version of the CSC methodology and applied it to primary myeloma patient specimens. Overall, our work creates a unique resource for the myeloma community. This study also supports unbiased surface proteomic profiling as a fruitful strategy for identifying new therapeutic targets and markers of drug resistance, that could have utility in improving myeloma patient outcomes. Similar approaches could be readily applied to additional tumor types or even models/tissues derived from other diseases.

PROBER identifies proteins associated with programmable sequence-specific DNA in living cells.

DNA-protein interactions mediate physiologic gene regulation and may be altered by DNA variants linked to polygenic disease. To enhance the speed and signal-to-noise ratio (SNR) in the identification and quantification of proteins associated with specific DNA sequences in living cells, we developed proximal biotinylation by episomal recruitment (PROBER). PROBER uses high-copy episomes to amplify SNR, and proximity proteomics (BioID) to identify the transcription factors and additional gene regulators associated with short DNA sequences of interest. PROBER quantified both constitutive and inducible association of transcription factors and corresponding chromatin regulators to target DNA sequences and binding quantitative trait loci due to single-nucleotide variants. PROBER identified alterations in regulator associations due to cancer hotspot mutations in the hTERT promoter, indicating that these mutations increase promoter association with specific gene activators. PROBER provides an approach to rapidly identify proteins associated with specific DNA sequences and their variants in living cells.

Allosteric HSP70 inhibitors perturb mitochondrial proteostasis and overcome proteasome inhibitor resistance in multiple myeloma.

Proteasome inhibitor (PI) resistance remains a central challenge in multiple myeloma. To identify pathways mediating resistance, we first mapped proteasome-associated genetic co-dependencies. We identified heat shock protein 70 (HSP70) chaperones as potential targets, consistent with proposed mechanisms of myeloma cells overcoming PI-induced stress. We therefore explored allosteric HSP70 inhibitors (JG compounds) as myeloma therapeutics. JG compounds exhibited increased efficacy against acquired and intrinsic PI-resistant myeloma models, unlike HSP90 inhibition. Shotgun and pulsed SILAC mass spectrometry demonstrated that JGs unexpectedly impact myeloma proteostasis by destabilizing the 55S mitoribosome. Our data suggest JGs have the most pronounced anti-myeloma effect not through inhibiting cytosolic HSP70 proteins but instead through mitochondrial-localized HSP70, HSPA9/mortalin. Analysis of myeloma patient data further supports strong effects of global proteostasis capacity, and particularly HSPA9 expression, on PI response. Our results characterize myeloma proteostasis networks under therapeutic pressure while motivating further investigation of HSPA9 as a specific vulnerability in PI-resistant disease.

The surfaceome of multiple myeloma cells suggests potential immunotherapeutic strategies and protein markers of drug resistance.

The myeloma surface proteome (surfaceome) determines tumor interaction with the microenvironment and serves as an emerging arena for therapeutic development. Here, we use glycoprotein capture proteomics to define the myeloma surfaceome at baseline, in drug resistance, and in response to acute drug treatment. We provide a scoring system for surface antigens and identify CCR10 as a promising target in this disease expressed widely on malignant plasma cells. We engineer proof-of-principle chimeric antigen receptor (CAR) T-cells targeting CCR10 using its natural ligand CCL27. In myeloma models we identify proteins that could serve as markers of resistance to bortezomib and lenalidomide, including CD53, CD10, EVI2B, and CD33. We find that acute lenalidomide treatment increases activity of MUC1-targeting CAR-T cells through antigen upregulation. Finally, we develop a miniaturized surface proteomic protocol for profiling primary plasma cell samples with low inputs. These approaches and datasets may contribute to the biological, therapeutic, and diagnostic understanding of myeloma.

Severe delayed hypersensitivity reactions to IL-1 and IL-6 inhibitors link to common HLA-DRB1*15 alleles.

OBJECTIVES: Drug reaction with eosinophilia and systemic symptoms (DRESS) is a severe, delayed hypersensitivity reaction (DHR). We observed DRESS to inhibitors of interleukin 1 (IL-1) or IL-6 in a small group of patients with Still's disease with atypical lung disease. We sought to characterise features of patients with Still's disease with DRESS compared with drug-tolerant Still's controls. We analysed human leucocyte antigen (HLA) alleles for association to inhibitor-related DHR, including in a small Kawasaki disease (KD) cohort. METHODS: In a case/control study, we collected a multicentre series of patients with Still's disease with features of inhibitor-related DRESS (n=66) and drug-tolerant Still's controls (n=65). We retrospectively analysed clinical data from all Still's subjects and typed 94/131 for HLA. European Still's-DRESS cases were ancestry matched to International Childhood Arthritis Genetics Consortium paediatric Still's cases (n=550) and compared for HLA allele frequencies. HLA association also was analysed using Still's-DRESS cases (n=64) compared with drug-tolerant Still's controls (n=30). KD subjects (n=19) were similarly studied. RESULTS: Still's-DRESS features included eosinophilia (89%), AST-ALT elevation (75%) and non-evanescent rash (95%; 88% involving face). Macrophage activation syndrome during treatment was frequent in Still's-DRESS (64%) versus drug-tolerant Still's (3%; p=1.2×10-14). We found striking enrichment for HLA-DRB1*15 haplotypes in Still's-DRESS cases versus INCHARGE Still's controls (p=7.5×10-13) and versus self-identified, ancestry-matched Still's controls (p=6.3×10-10). In the KD cohort, DRB1*15:01 was present only in those with suspected anakinra reactions. CONCLUSIONS: DRESS-type reactions occur among patients treated with IL-1/IL-6 inhibitors and strongly associate with common HLA-DRB1*15 haplotypes. Consideration of preprescription HLA typing and vigilance for serious reactions to these drugs are warranted.

Dnmt3a deficiency in the skin causes focal, canonical DNA hypomethylation and a cellular proliferation phenotype.

DNA hypomethylation is a feature of epidermal cells from aged and sun-exposed skin, but the mechanisms responsible for this methylation loss are not known. Dnmt3a is the dominant de novo DNA methyltransferase in the skin; while epidermal Dnmt3a deficiency creates a premalignant state in which keratinocytes are more easily transformed by topical mutagens, the conditions responsible for this increased susceptibility to transformation are not well understood. Using whole genome bisulfite sequencing, we identified a focal, canonical DNA hypomethylation phenotype in the epidermal cells of Dnmt3a-deficient mice. Single-cell transcriptomic analysis revealed an increased proportion of cells with a proliferative gene expression signature, while other populations in the skin were relatively unchanged. Although total DNMT3A deficiency has not been described in human disease states, rare patients with an overgrowth syndrome associated with behavioral abnormalities and an increased risk of cancer often have heterozygous, germline mutations in DNMT3A that reduce its function (Tatton-Brown Rahman syndrome [TBRS]). We evaluated the DNA methylation phenotype of the skin from a TBRS patient with a germline DNMT3AR882H mutation, which encodes a dominant-negative protein that reduces its methyltransferase function by ∼80%. We detected a focal, canonical hypomethylation phenotype that revealed considerable overlap with hypomethylated regions found in Dnmt3a-deficient mouse skin. Together, these data suggest that DNMT3A loss creates a premalignant epigenetic state associated with a hyperproliferative phenotype in the skin and further suggest that DNMT3A acts as a tumor suppressor in the skin.

Proteasome inhibitor-induced modulation reveals the spliceosome as a specific therapeutic vulnerability in multiple myeloma.

Enhancing the efficacy of proteasome inhibitors (PI) is a central goal in myeloma therapy. We proposed that signaling-level responses after PI may reveal new mechanisms of action that can be therapeutically exploited. Unbiased phosphoproteomics after treatment with the PI carfilzomib surprisingly demonstrates the most prominent phosphorylation changes on splicing related proteins. Spliceosome modulation is invisible to RNA or protein abundance alone. Transcriptome analysis after PI demonstrates broad-scale intron retention, suggestive of spliceosome interference, as well as specific alternative splicing of protein homeostasis machinery components. These findings lead us to evaluate direct spliceosome inhibition in myeloma, which synergizes with carfilzomib and shows potent anti-tumor activity. Functional genomics and exome sequencing further support the spliceosome as a specific vulnerability in myeloma. Our results propose splicing interference as an unrecognized modality of PI mechanism, reveal additional modes of spliceosome modulation, and suggest spliceosome targeting as a promising therapeutic strategy in myeloma.

Evaluating the efficacy of multiple myeloma cell lines as models for patient tumors via transcriptomic correlation analysis.

Multiple myeloma (MM) cell lines are routinely used to model the disease. However, a long-standing question is how well these cell lines truly represent tumor cells in patients. Here, we employ a recently described method of transcriptional correlation profiling to compare similarity of 66 MM cell lines to 779 newly diagnosed MM patient tumors. We found that individual MM lines differ significantly with respect to patient tumor representation, with median R ranging from 0.35 to 0.54. ANBL-6 was the "best" line, markedly exceeding all others (p < 2.2e-16). Notably, some widely used cell lines (RPMI-8226, U-266) scored poorly in our patient similarity ranking (48 and 52 of 66, respectively). Lines cultured with interleukin-6 showed significantly improved correlations with patient tumor (p = 9.5e-4). When common MM genomic features were matched between cell lines and patients, only t(4;14) and t(14;16) led to increased transcriptional correlation. To demonstrate the utility of our top-ranked line for preclinical studies, we showed that intravenously implanted ANBL-6 proliferates in hematopoietic organs in immunocompromised mice. Overall, our large-scale quantitative correlation analysis, utilizing emerging datasets, provides a resource informing the MM community of cell lines that may be most reliable for modeling patient disease while also elucidating biological differences between cell lines and tumors.

Integrated phosphoproteomics and transcriptional classifiers reveal hidden RAS signaling dynamics in multiple myeloma.

A major driver of multiple myeloma (MM) is thought to be aberrant signaling, yet no kinase inhibitors have proven successful in the clinic. Here, we employed an integrated, systems approach combining phosphoproteomic and transcriptome analysis to dissect cellular signaling in MM to inform precision medicine strategies. Unbiased phosphoproteomics initially revealed differential activation of kinases across MM cell lines and that sensitivity to mammalian target of rapamycin (mTOR) inhibition may be particularly dependent on mTOR kinase baseline activity. We further noted differential activity of immediate downstream effectors of Ras as a function of cell line genotype. We extended these observations to patient transcriptome data in the Multiple Myeloma Research Foundation CoMMpass study. A machine-learning-based classifier identified surprisingly divergent transcriptional outputs between NRAS- and KRAS-mutated tumors. Genetic dependency and gene expression analysis revealed mutated Ras as a selective vulnerability, but not other MAPK pathway genes. Transcriptional analysis further suggested that aberrant MAPK pathway activation is only present in a fraction of RAS-mutated vs wild-type RAS patients. These high-MAPK patients, enriched for NRAS Q61 mutations, have inferior outcomes, whereas RAS mutations overall carry no survival impact. We further developed an interactive software tool to relate pharmacologic and genetic kinase dependencies in myeloma. Collectively, these predictive models identify vulnerable signaling signatures and highlight surprising differences in functional signaling patterns between NRAS and KRAS mutants invisible to the genomic landscape. These results will lead to improved stratification of MM patients in precision medicine trials while also revealing unexplored modes of Ras biology in MM.

Emergent high fatality lung disease in systemic juvenile arthritis.

OBJECTIVE: To investigate the characteristics and risk factors of a novel parenchymal lung disease (LD), increasingly detected in systemic juvenile idiopathic arthritis (sJIA). METHODS: In a multicentre retrospective study, 61 cases were investigated using physician-reported clinical information and centralised analyses of radiological, pathological and genetic data. RESULTS: LD was associated with distinctive features, including acute erythematous clubbing and a high frequency of anaphylactic reactions to the interleukin (IL)-6 inhibitor, tocilizumab. Serum ferritin elevation and/or significant lymphopaenia preceded LD detection. The most prevalent chest CT pattern was septal thickening, involving the periphery of multiple lobes ± ground-glass opacities. The predominant pathology (23 of 36) was pulmonary alveolar proteinosis and/or endogenous lipoid pneumonia (PAP/ELP), with atypical features including regional involvement and concomitant vascular changes. Apparent severe delayed drug hypersensitivity occurred in some cases. The 5-year survival was 42%. Whole exome sequencing (20 of 61) did not identify a novel monogenic defect or likely causal PAP-related or macrophage activation syndrome (MAS)-related mutations. Trisomy 21 and young sJIA onset increased LD risk. Exposure to IL-1 and IL-6 inhibitors (46 of 61) was associated with multiple LD features. By several indicators, severity of sJIA was comparable in drug-exposed subjects and published sJIA cohorts. MAS at sJIA onset was increased in the drug-exposed, but was not associated with LD features. CONCLUSIONS: A rare, life-threatening lung disease in sJIA is defined by a constellation of unusual clinical characteristics. The pathology, a PAP/ELP variant, suggests macrophage dysfunction. Inhibitor exposure may promote LD, independent of sJIA severity, in a small subset of treated patients. Treatment/prevention strategies are needed.

T Cell Receptor-Independent, CD31/IL-17A-Driven Inflammatory Axis Shapes Synovitis in Juvenile Idiopathic Arthritis.

T cells are considered autoimmune effectors in juvenile idiopathic arthritis (JIA), but the antigenic cause of arthritis remains elusive. Since T cells comprise a significant proportion of joint-infiltrating cells, we examined whether the environment in the joint could be shaped through the inflammatory activation by T cells that is independent of conventional TCR signaling. We focused on the analysis of synovial fluid (SF) collected from children with oligoarticular and rheumatoid factor-negative polyarticular JIA. Cytokine profiling of SF showed dominance of five molecules including IL-17A. Cytometric analysis of the same SF samples showed enrichment of αßT cells that lacked both CD4 and CD8 co-receptors [herein called double negative (DN) T cells] and also lacked the CD28 costimulatory receptor. However, these synovial αßT cells expressed high levels of CD31, an adhesion molecule that is normally employed by granulocytes when they transit to sites of injury. In receptor crosslinking assays, ligation of CD31 alone on synovial CD28nullCD31+ DN αßT cells effectively and sufficiently induced phosphorylation of signaling substrates and increased intracytoplasmic stores of cytokines including IL-17A. CD31 ligation was also sufficient to induce RORγT expression and trans-activation of the IL-17A promoter. In addition to T cells, SF contained fibrocyte-like cells (FLC) expressing IL-17 receptor A (IL-17RA) and CD38, a known ligand for CD31. Stimulation of FLC with IL-17A led to CD38 upregulation, and to production of cytokines and tissue-destructive molecules. Addition of an oxidoreductase analog to the bioassays suppressed the CD31-driven IL-17A production by T cells. It also suppressed the downstream IL-17A-mediated production of effectors by FLC. The levels of suppression of FLC effector activities by the oxidoreductase analog were comparable to those seen with corticosteroid and/or biologic inhibitors to IL-6 and TNFα. Collectively, our data suggest that activation of a CD31-driven, αßTCR-independent, IL-17A-mediated T cell-FLC inflammatory circuit drives and/or perpetuates synovitis. With the notable finding that the oxidoreductase mimic suppresses the effector activities of synovial CD31+CD28null αßT cells and IL-17RA+CD38+ FLC, this small molecule could be used to probe further the intricacies of this inflammatory circuit. Such bioactivities of this small molecule also provide rationale for new translational avenue(s) to potentially modulate JIA synovitis.

Essential function of NHE8 in mouse retina demonstrated by AAV-mediated CRISPR/Cas9 knockdown.

We studied the role of sodium/proton exchanger 8 (NHE8) in retinal pigment epithelium (RPE) and photoreceptor cells of adult mouse retina by using the clustered regularly interspaced short palindromic repeats (CRISPR)-associated endonuclease (Cas)9 from Neisseria meningitidis (Nm). Specific single guide RNAs (sgRNAs) were designed to knockdown the Slc9a8 gene, which encodes the NHE8. Nuclease null NmCas9 and sgRNAs were packaged respectively using adeno-associated viral vector (AAV), and delivered into mouse eyes in vivo by subretinal injection on wild-type mice of about four-week-old when mouse retina is fully developed. Eye samples were collected four weeks after injection for phenotype examination. Real-time PCR analysis demonstrated ∼38% reduction of NHE8 transcripts in retinas injected with AAV-knockdown sgRNA and AAV-Cas9. Loss of photoreceptor cells was found in eyes injected with AAV-knockdown sgRNA and AAV-Cas9 under either the human rhodopsin promoter or the minimal chicken ß-actin promoter, while normal morphology was observed in control eyes injected with AAV-Cas9 and AAV-control sgRNA; immunostaining data showed degenerating photoreceptor cells and RPE cells in eyes injected with knockdown sgRNA and Cas9 AAVs. We further determined that mutant M120K-NHE8 displayed altered intracellular pH regulation in human RPE and primary mouse RPE cells using genetically encoded pH sensor pHluorin and that primary cultured NHE8 mutant RPE cells showed different pH titration curves. These results indicate that NHE8 plays essential function in both RPE and photoreceptor cells. NHE8 dysfunction either in photoreceptor or RPE is sufficient to cause retinal degeneration in adult mice at any age.

Repurposing tofacitinib as an anti-myeloma therapeutic to reverse growth-promoting effects of the bone marrow microenvironment.

The myeloma bone marrow microenvironment promotes proliferation of malignant plasma cells and resistance to therapy. Activation of JAK/STAT signaling is thought to be a central component of these microenvironment-induced phenotypes. In a prior drug repurposing screen, we identified tofacitinib, a pan-JAK inhibitor Food and Drug Administration (FDA) approved for rheumatoid arthritis, as an agent that may reverse the tumor-stimulating effects of bone marrow mesenchymal stromal cells. Herein, we validated in vitro, in stromal-responsive human myeloma cell lines, and in vivo, in orthotopic disseminated xenograft models of myeloma, that tofacitinib showed efficacy in myeloma models. Furthermore, tofacitinib strongly synergized with venetoclax in coculture with bone marrow stromal cells but not in monoculture. Surprisingly, we found that ruxolitinib, an FDA approved agent targeting JAK1 and JAK2, did not lead to the same anti-myeloma effects. Combination with a novel irreversible JAK3-selective inhibitor also did not enhance ruxolitinib effects. Transcriptome analysis and unbiased phosphoproteomics revealed that bone marrow stromal cells stimulate a JAK/STAT-mediated proliferative program in myeloma cells, and tofacitinib reversed the large majority of these pro-growth signals. Taken together, our results suggest that tofacitinib reverses the growth-promoting effects of the tumor microenvironment. As tofacitinib is already FDA approved, these results can be rapidly translated into potential clinical benefits for myeloma patients.