Dependence of peripheral T-cell lymphoma on constitutively activated JAK3: Implication for JAK3 inhibition as a therapeutic approach.

Peripheral T-cell lymphoma (PTCL) is a clinically heterogeneous group that represents 10%-15% of all lymphomas. Despite improved genetic and molecular understanding, treatment outcomes for PTCL have not shown significant improvement. Although Janus kinase-2 (JAK2) plays an important role in myeloproliferative neoplasms, the critical role of JAK isoforms in mediating prosurvival signaling in PTCL cells is not well defined. Immunohistochemical analysis of PTCL tumors (n = 96) revealed high levels of constitutively active JAK3 (pJAK3) that significantly (p < 0.04) correlated with the activation state of its canonical substrate STAT3. Furthermore, constitutive activation of JAK3 and STAT3 positively correlated, at least in part, with an oncogenic tyrosine phosphatase PTPN11. Pharmacological inhibition of JAK3 but not JAK1/JAK2 significantly (p < 0.001) decreased PTCL proliferation, survival and STAT3 activation. A sharp contrast was observed in the pJAK3 positivity between ALK+ (85.7%) versus ALK-negative (10.0%) in human PTCL tumors and PTCL cell lines. Moreover, JAK3 and ALK reciprocally interacted in PTCL cells, forming a complex to possibly regulate STAT3 signaling. Finally, combined inhibition of JAK3 (by WHI-P154) and ALK (by crizotinib or alectinib) significantly (p < 0.01) decreased the survival of PTCL cells as compared to either agent alone by inhibiting STAT3 downstream signaling. Collectively, our findings establish that JAK3 is a therapeutic target for a subset of PTCL, and provide rationale for the clinical evaluation of JAK3 inhibitors combined with ALK-targeted therapy in PTCL.

The Impact of COVID-19 Health and Safety Measures on the Self-Reported Exercise Behaviors and Mental Health of College Students.

The public-health restrictions (e.g., remote learning, restricted access to facilities and dining halls) put in place by colleges to reduce the spread of COVID-19 resulted in forced isolation and modifications to health-related behaviors. The restrictions and uncertainty associated with COVID-19 may have exacerbated the challenges of meeting exercise recommendations and mental-health concerns. The purpose of this study was to assess the impact of restrictions on students' exercise habits and their levels of anxiety, stress, and depression. Five-hundred and forty students completed a 29-question survey on individual demographics, living arrangements, exercise, sleep, diet, and mental health. Significant changes in weekly days of exercise and intensity were reported. Increases in anxiety, stress, and depression were reported. The two most frequently reported changes in exercise behavior were an increase in minutes of aerobic training (5%) and a combination of reduced minutes of aerobic and resistance training (3.9%), which could be reflective of an individual's ability and/or desire to maintain exercise behavior during the restrictions. Alternatively, for those students who reduced their exercise habits, aerobic training (11%) was the mode that suffered the most. Demographic factors such as ethnicity, regional residence, and gender were found to have significant effects on stress, anxiety, and depression. Amidst pandemics and future health emergencies, colleges should prioritize establishing opportunities for students to exercise, helping them meet physical activity recommendations and combat mental-health issues.

Resilient pedagogy: experiences of kinesiology faculty during COVID-19.

The COVID-19 pandemic required an emergency shift to remote teaching. Despite their limited previous experience with online or hybrid teaching, our cohort of kinesiology faculty (n = 112) had high confidence in their ability to deliver quality educational experiences for their students during the pandemic. With support from their institutions, technology departments, and teaching and learning centers, faculty developed new skills and organizational strategies. To achieve this, 81% of faculty reported needing extra course preparation time to deliver high-quality remote teaching, with 51% needing up to 5 extra hours per week per course. There is a fraction of faculty from this study excited about the prospect of teaching online in the future. These newfound online teaching skills should be leveraged to modernize course offerings in kinesiology departments, supporting student recruitment, retention, and success.NEW & NOTEWORTHY The COVID-19 pandemic caused temporary and permanent changes to higher education, specifically kinesiology programs. This article highlights the resiliency of faculty in kinesiology programs, how they adapted, where they felt supported, and what they hope to bring with them into their future pedagogy practices.

Impact of COVID-19 on access to laboratories and human participants: exercise science faculty perspectives.

Restrictions due to the coronavirus (COVID-19) pandemic impacted the ability of faculty and students in exercise science to work in lab settings with human participants. The purpose of this study was to determine how exercise science faculty were impacted by COVID-19 restrictions with respect to access and use of exercise science lab and research facilities. Of the 100 surveyed participants categorized as requiring access to people and lab spaces (lab-based faculty), 61% (n = 61) reported decreased research productivity with 87% (n = 53) of those faculty in one or more of the following subdisciplines: exercise physiology, clinical exercise physiology, or biomechanics. Of all lab-based faculty, 40% (n = 40) participants reported having access to students and lab spaces and 55% (n = 55) indicated they were allowed to conduct in-person research. Of tenure-track lab-based faculty, 80% (n = 20) reported a decrease in research productivity, of which 60.0% (n = 12) identified as female. Among faculty with 5 or less years of teaching experience (n = 23), 69.6% (n = 16) reported a decrease in productivity, with 68.8% (n = 11) of those being female. All exercise science faculty surveyed reported issues with safety and social distancing, modified lab and research procedures, faculty workload, and research productivity. This information can be leveraged to create better infrastructure to support faculty and develop and implement strategies to reduce workload inequities.

Faculty perceptions of the exercise science student learning experience during the coronavirus pandemic.

Significant disruptions in higher education course delivery occurred during the coronavirus (COVID-19) global pandemic. The implementation of emergency remote teaching (ERT) offered exercise science faculty a safe method to continue educating students in courses generally taught face-to-face. The purpose of this investigation was to explore faculty perceptions of their ERT efforts with respect to student successes, challenges, and faculty expectations. Through an electronic survey, participants (n = 112) from higher education institutions in 31 states and three Canadian provinces provided feedback on their perceptions of the student experience across 315 fall 2020 courses. Data analysis included a thematic analysis to identify themes and trends in participant responses. Faculty identified student adaptability, increased autonomy of learning, and maintenance of learning as successes. Also noted was the increased flexibility of alternative pedagogy methods. Participants perceived student challenges related to technology, time management, and well-being. Faculty perceived students expected increased accommodations and instructor responsiveness during fall 2020. While faculty and students were challenged to adapt during the global pandemic, the perceived ERT experiences during COVID-19 highlight the resiliency of higher education students and underscores changes needed by educational institutions to provide resources and training upon return to traditional education or in response to a future crisis.

MCIR1: A patient-derived mantle cell lymphoma line for discovering new treatments for ibrutinib resistance.

BACKGROUND: Despite the unprecedented success of ibrutinib in lymphoma therapy, the development of ibrutinib resistance due to acquired BTK or PLCγ2 mutations has become a new clinical problem. However, not all resistance is mediated by these mutations and these mechanisms are poorly understood due to a lack of study tools that truly recapitulate this clinical scenario. METHODS: We established a novel patient-derived ibrutinib-resistant mantle cell lymphoma (MCL) line named MCIR1. Using immunological, molecular, and cytogenetic approaches, we comprehensively characterized MCIR1 and further demonstrated its utility in the study of resistance mechanisms and treatments to overcome this resistance. RESULTS: We show that MCIR1 is a bona fide ibrutinib-resistant MCL cell line with normal BTK-/PLCγ2 but ibrutinib-resistant ERK1/2 and AKT1 signaling. RNA-Seq analysis revealed a robust non-canonical NF-kB signaling that drives the ibrutinib resistance. We also demonstrate the potential utility of a MCIR1-based cell and mouse model for the discovery of new treatments to overcome BTK inhibitor resistance. CONCLUSIONS: We have established the first patient-derived ibrutinib-resistant MCL cell line MCIR1 that lacks BTK or PLCγ2 mutations but exhibits a hyperactive non-canonical NF-kB pathway. We further demonstrate its utility in the discovery and validation of new drugs to overcome this resistance.

Salicylates enhance CRM1 inhibitor antitumor activity by induction of S-phase arrest and impairment of DNA-damage repair.

Chromosome region maintenance protein 1 (CRM1) mediates protein export from the nucleus and is a new target for anticancer therapeutics. Broader application of KPT-330 (selinexor), a first-in-class CRM1 inhibitor recently approved for relapsed multiple myeloma and diffuse large B-cell lymphoma, have been limited by substantial toxicity. We discovered that salicylates markedly enhance the antitumor activity of CRM1 inhibitors by extending the mechanisms of action beyond CRM1 inhibition. Using salicylates in combination enables targeting of a range of blood cancers with a much lower dose of selinexor, thereby potentially mitigating prohibitive clinical adverse effects. Choline salicylate (CS) with low-dose KPT-330 (K+CS) had potent, broad activity across high-risk hematological malignancies and solid-organ cancers ex vivo and in vivo. The K+CS combination was not toxic to nonmalignant cells as compared with malignant cells and was safe without inducing toxicity to normal organs in mice. Mechanistically, compared with KPT-330 alone, K+CS suppresses the expression of CRM1, Rad51, and thymidylate synthase proteins, leading to more efficient inhibition of CRM1-mediated nuclear export, impairment of DNA-damage repair, reduced pyrimidine synthesis, cell-cycle arrest in S-phase, and cell apoptosis. Moreover, the addition of poly (ADP-ribose) polymerase inhibitors further potentiates the K+CS antitumor effect. K+CS represents a new class of therapy for multiple types of blood cancers and will stimulate future investigations to exploit DNA-damage repair and nucleocytoplasmic transport for cancer therapy in general.

Effects of guided mindfulness meditation on anxiety and stress in a pre-healthcare college student population: a pilot study.

Objective: To identify the effects of guided mindfulness meditation on anxiety and stress in pre-healthcare college students. Participants: Students (n = 33, age 19-22 years) were tested between September and November of 2017. Methods: Students completed 5-12 minutes of meditation 6 days/week for 8 weeks. We examined differences in pre- and post-intervention stress, anxiety, mindfulness, and heart rate variability. Results: All variables significantly improved after the intervention. When broken into quartiles based on minutes of meditation, groups 1 (0-184 min, p = 0.044) and 2 (184.1-268 min, p = 0.042) significantly increased mindfulness after the intervention. Group 3 (268-350 min) significantly decreased state anxiety (p = 0.015) and increased mindfulness (p = 0.029). Group 4 (350.24-424.05 min) decreased stress (p = 0.003), state anxiety (p = 0.007), trait anxiety (p = 0.003), and increased mindfulness (p = 0.007). Conclusion: Five to twelve minutes of daily mindfulness meditation is associated with decreased stress and anxiety, and increased mindfulness with greater changes observed following more minutes of meditation.

Targeting glycogen synthase kinase 3 for therapeutic benefit in lymphoma.

Targeting the B-cell receptor and phosphatidylinositol 3-kinase/mTOR signaling pathways has shown meaningful, but incomplete, antitumor activity in lymphoma. Glycogen synthase kinase 3 (GSK3) α and ß are 2 homologous and functionally overlapping serine/threonine kinases that phosphorylate multiple protein substrates in several key signaling pathways. To date, no agent targeting GSK3 has been approved for lymphoma therapy. We show that lymphoma cells abundantly express GSK3α and GSK3ß compared with normal B and T lymphocytes at the messenger RNA and protein levels. Utilizing a new GSK3 inhibitor 9-ING-41 and by genetic deletion of GSK3α and GSK3ß genes using CRISPR/CAS9 knockout, GSK3 was demonstrated to be functionally important to lymphoma cell growth and proliferation. GSK3ß binds to centrosomes and microtubules, and lymphoma cells treated with 9-ING-41 become arrested in mitotic prophase, supporting the notion that GSK3ß is necessary for the progression of mitosis. By analyzing recently published RNA sequencing data on 234 diffuse large B-cell lymphoma patients, we found that higher expression of GSK3α or GSK3ß correlates well with shorter overall survival. These data provide rationale for testing GSK3 inhibitors in lymphoma patient trials.

Prognostic and therapeutic significance of phosphorylated STAT3 and protein tyrosine phosphatase-6 in peripheral-T cell lymphoma.

Peripheral T cell lymphomas (PTCL) is a heterogenous group of non-Hodgkin lymphoma and many patients remain refractory to the frontline therapy. Identifying new prognostic markers and treatment is an unmet need in PTCL. We analyzed phospho-STAT3 (pSTAT3) expression in a cohort of 169 PTCL tumors and show overall 38% positivity with varied distribution among PTCL subtypes with 27% (16/59) in PTCL-NOS; 29% (11/38) in AITL, 57% (13/28) in ALK-negative ALCL, and 93% in ALK-pos ALCL (14/15), respectively. Correlative analysis indicated an adverse correlation between pSTAT3 and overall survival (OS). PTPN6, a tyrosine phosphatase and potential negative regulator of STAT3 activity, was suppressed in 62% of PTCL-NOS, 42% of AITL, 60% ALK-neg ALCL, and 86% of ALK-pos ALCL. Loss of PTPN6 combined with pSTAT3 positivity predicted an infwere considered significantferior OS in PTCL cases. In vitro treatment of TCL lines with azacytidine (aza), a DNA methyltransferase inhibitor (DNMTi), restored PTPN6 expression and decreased pSTAT3. Combining DNMTi with JAK3 inhibitor resulted in synergistic antitumor activity in SUDHL1 cell line. Overall, our results suggest that PTPN6 and activated STAT3 can be developed as prognostic markers, and the combination of DNMTi and JAK3 inhibitors as a novel treatment for patients with PTCL subtypes.

5000 Meter Run Performance is not Enhanced 24 Hrs After an Intense Exercise Bout and Cold Water Immersion.

Cold water immersion (CWI) is used by endurance athletes to speed recovery between exercise bouts, but little evidence is available on the effects of CWI on subsequent endurance performance. The purpose of this study was to investigate the effects of CWI following an acute bout of interval training on 5000 m run performance 24 hrs after interval training, perceived muscle soreness (PMS), range of motion (ROM), thigh circumference (TC), and perceived exertion (RPE). Nine endurance-trained males completed 2 trials, each consisting of an interval training session of 8 repetitions of 1200 m at a running pace equal to 75% of VO2peak, either a control or CWI treatment, and a timed 5000 m run 24 hrs post interval training session. CWI was performed for 12 min at 12 degrees Celsius on the legs. Recovery treatments were performed in a counterbalanced design. Run time for 5000 m was not different between the CWI and control trials (CWI = 1317.33 ± 128.33 sec, control = 1303.44 ± 105.53 sec; p = 0.48). PMS increased significantly from baseline to immediately post exercise (BL = 1.17 ± 0.22, POST = 2.81 ± 0.52; p = 0.02) and remained elevated from baseline to 24 hrs post exercise (POST24 = 2.19 ± 0.32; p = 0.02), but no difference was observed between the treatments. No differences were observed for the interaction between time and treatment for TC (λ = 0.73, p = 0.15) and ROM (λ = 0.49; p = 0.10). CWI performed immediately following an interval training exercise bout did not enhance subsequent 5000 m run performance or reduce PMS. CWI may not provide a recovery or performance advantage when athletes are accustomed to the demands of the prior exercise bout.

Drugs with anti-oxidant properties can interfere with cell viability measurements by assays that rely on the reducing property of viable cells.

Cell viability assays such as Cell Titer Blue and Alamar Blue rely on the reducing property of viable cells to reduce the reagent dye to a product which gives a fluorescent signal. The current manufacture-recommended protocols do not take into account the possibility of the reagent substrate being reduced directly to the fluorescent product by drugs with an anti-oxidant property. After suspecting spurious results while determining the cytotoxic potential of a drug of interest (DOI) with known anti-oxidant property against a renal cell cancer (RCC) cell line, we aimed to establish that drugs with anti-oxidant property can indeed cause false-negative results with the current protocols of these assays by direct reduction of the reagent substrate. We also aimed to counter the same with a simple modification added to the protocol. Through our experiments, we conclusively demonstrate that drugs with anti-oxidant properties can indeed interfere with cell viability measurements by assays that rely on the reducing property of viable cells. A simple modification in the protocol, as elaborated in the manuscript, can prevent spurious results with these otherwise convenient assays.Laboratory Investigation advance online publication, 27 February 2017; doi:10.1038/labinvest.2017.18.

Loss of function mutations in PTPN6 promote STAT3 deregulation via JAK3 kinase in diffuse large B-cell lymphoma.

PTPN6 (SHP1) is a tyrosine phosphatase that negatively controls the activity of multiple signaling pathways including STAT signaling, however role of mutated PTPN6 is not much known. Here we investigated whether PTPN6 might also be a potential target for diffuse large B cell lymphoma (DLBCL) and performed Sanger sequencing of the PTPN6 gene. We have identified missense mutations within PTPN6 (N225K and A550V) in 5% (2/38) of DLBCL tumors. Site directed mutagenesis was performed to mutate wild type (WT) PTPN6 and stable cell lines were generated by lentiviral transduction of PTPN6(WT), PTPN6(N225K) and PTPN6(A550V) constructs, and effects of WT or mutated PTPN6 on STAT3 signaling were analyzed. WT PTPN6 dephosphorylated STAT3, but had no effect on STAT1, STAT5 or STAT6 phosphorylation. Both PTPN6 mutants were unable to inhibit constitutive, as well as cytokines induced STAT3 activation. Both PTPN6 mutants also demonstrated reduced tyrosine phosphatase activity and exhibited enhanced STAT3 transactivation activity. Intriguingly, a lack of direct binding between STAT3 and WT or mutated PTPN6 was observed. However, compared to WT PTPN6, cells expressing PTPN6 mutants exhibited increased binding between JAK3 and PTPN6 suggesting a more dynamic interaction of PTPN6 with upstream regulators of STAT3. Consistent with this notion, both the mutants demonstrated increased resistance to JAK3 inhibitor, WHIP-154 relative to WT PTPN6. Overall, this is the first study, which demonstrates that N225K and A550V PTPN6 mutations cause loss-of-function leading to JAK3 mediated deregulation of STAT3 pathway and uncovers a mechanism that tumor cells can use to control PTPN6 substrate specificity.

The mTORC1 inhibitor everolimus has antitumor activity in vitro and produces tumor responses in patients with relapsed T-cell lymphoma.

Everolimus is an oral agent that targets the mammalian target of rapamycin (mTOR) pathway. This study investigated mTOR pathway activation in T-cell lymphoma (TCL) cell lines and assessed antitumor activity in patients with relapsed/refractory TCL in a phase 2 trial. The mTOR pathway was activated in all 6 TCL cell lines tested and everolimus strongly inhibited malignant T-cell proliferation with minimal cytotoxic effects. Everolimus completely inhibited phosphorylation of ribosomal S6, a raptor/mTOR complex 1 (mTORC1) target, without a compensatory activation of the rictor/mTORC2 target Akt (S475). In the clinical trial, 16 patients with relapsed TCL were enrolled and received everolimus 10 mg by mouth daily. Seven patients (44%) had cutaneous (all mycosis fungoides); 4 (25%) had peripheral T cell not otherwise specified; 2 (13%) had anaplastic large cell; and 1 each had extranodal natural killer/T cell, angioimmunoblastic, and precursor T-lymphoblastic leukemia/lymphoma types. The overall response rate was 44% (7/16; 95% confidence interval [CI]: 20% to 70%). The median progression-free survival was 4.1 months (95% CI, 1.5-6.5) and the median overall survival was 10.2 months (95% CI, 2.6-44.3). The median duration of response for the 7 responders was 8.5 months (95% CI, 1.0 to not reached). These studies indicate that everolimus has antitumor activity and provide proof-of-concept that targeting the mTORC1 pathway in TCL is clinically relevant. This trial was registered at www.clinicaltrials.gov as #NCT00436618.

Translation initiation complex eIF4F is a therapeutic target for dual mTOR kinase inhibitors in non-Hodgkin lymphoma.

Deregulated mRNA translation has been implicated in disease development and in part is controlled by a eukaryotic initiation complex eIF4F (composed of eIF4E, eIF4G and eIF4A). We demonstrate here that the cap bound fraction from lymphoma cells was enriched with eIF4G and eIF4E indicating that lymphoma cells exist in an activated translational state. Moreover, 77% (110/142) of diffuse large B cell lymphoma tumors expressed eIF4E and this was associated with an inferior event free survival. Over-expression of wild-type eIF4E (eIF4E(WT)) but not cap-mutant eIF4E (eIF4E(cap mutant)) increased the activation of the eIF4F complex. Treatment with the active-site dual mTOR inhibitor CC214-1 reduced the level of the eIF4F complex by decreasing the cap bound fraction of eIF4G and increasing the levels of 4E-BP1. CC214-1 inhibited both the cap dependent and global protein translation. CC214-1 inhibited c-Myc, and cyclin D3 translation by decreasing polysomal fractions from lymphoma cells. Inhibition of eIF4E with shRNA further decreased the CC214-1 induced inhibition of the eIF4F complex, c-Myc, cyclin D3 translation, and colony formation. These studies demonstrate that the eIF4F complex is deregulated in aggressive lymphoma and that dual mTOR therapy has therapeutic potential in these patients.

Elevated soluble IL-2Rα, IL-8, and MIP-1ß levels are associated with inferior outcome and are independent of MIPI score in patients with mantle cell lymphoma.

Mantle cell lymphoma (MCL) is a unique type of lymphoma with a prognosis intermediate between indolent and aggressive types. The purpose of this study was to study blood cytokine levels in newly diagnosed and relapsed MCL patients with respect to patterns of abnormalities and relationship to the MCL International Prognostic Index (MIPI) score. We analyzed blood levels of 30 cytokines using a multiplex ELISA in 88 patients with newly diagnosed MCL (pre-treatment levels) and 20 with relapsed MCL and compared them with controls without known lymphoma. Elevated cytokine levels were compared with clinical outcome and the MIPI score. In the 88 newly diagnosed MCL patients, we found significantly elevated levels compared with controls of IL-12, IP-10, sIL-2Rα, MIG, IL-1RA, IL-8, MIP-1α, and MIP-1ß (all P < 0.05). Of these elevated cytokines, sIL-2Rα, IL-8, MIG, MIP-1α, and MIP-1ß were predictive of inferior event-free survival, and sIL-2Rα (HR = 1.94; P = 0.038), IL-8 (HR = 2.17; P = 0.015), and MIP-1ß (HR = 2.10; P = 0.016) were independent of MIPI score; only sIL-2Rα (HR = 2.35; P = 0.041) was associated with overall survival after adjustment for MIPI. In the relapsed MCL patient group, the only significantly elevated plasma cytokines that predicted EFS were sIL-2Rα (HR = 2.90; P = 0.04) and IL-8 (HR = 3.75; P = 0.02). Elevated blood levels of sIL-2Rα and the pro-inflammatory cytokines IL-8 and MIP-1ß are poor prognostic factors in MCL patients and independent of MIPI score. These factors, if validated, will provide important additions to the MIPI and guide the development of new therapies for patients with elevated levels of these cytokines.

Elevated serum monoclonal and polyclonal free light chains and interferon inducible protein-10 predicts inferior prognosis in untreated diffuse large B-cell lymphoma.

The detection of serum free light (FLC) is useful in the diagnosis of several hematological diseases. The role and biological relevance of monoclonal or polyclonal FLC elevations in predicting long-term outcome in diffuse large B-cell lymphoma (DLBCL) is unknown. We determined the relationship of the type of FLC elevations to outcome, tumor genotype, and pattern of serum cytokine elevations in 276 patients with untreated DLBCL. Elevated FLC was an adverse prognostic factor through 6 years of follow-up (monoclonal, Event free survival (EFS) HR = 3.56, 95% CI: 1.88-6.76, P <0.0001; polyclonal, EFS HR = 2.56, 95% CI: 1.50-4.38, P = 0.0006). About 73% of DLBCL tumors with monoclonal FLC elevations were activated B-cell type (ABC) versus 33% from patients with normal FLC. Only ABC-DLBCL lines secreted kappa FLC in vitro and this secretion could be inhibited by the NF-κB inhibitor bortezomib. Patients with monoclonal FLC had significantly (all P <0.001) increased serum levels of IL-12, sIL-2Rα, IL-1R, and IP-10. Patients with polyclonal elevations of FLC had higher levels of IL-6 (P = 0.033), IL-8 (P =0.025), sIL2Rα (P = 0.011), and IL-1R1 (P = 0.041). The combination of elevated FLC and a CXC superfamily chemokine IP-10 predicted a particularly inferior outcome characterized by late relapse. These increased abnormal FLC and cytokines are potentially useful biomarkers for prognosis and selecting agents for untreated DLBCL.

Elevated serum IL-10 levels in diffuse large B-cell lymphoma: a mechanism of aberrant JAK2 activation.

Cytokines are deregulated in cancers and can contribute to tumor growth. In patients with diffuse large-cell lymphoma (DLBCL), we observed higher levels of JAK/STAT pathway-related serum cytokines (ie, IL-6, IL-10, epidermal growth factor, and IL-2) compared with controls. Of these, only IL-10 activated the JAK2 pathway in lymphoma cells in vitro. Patients with high serum IL-10 had shorter event-free survival (EFS) than patients with low levels (P > .01) and high IL-10 was correlated with high lactase dehydrogenase (P = .0085) and higher International Prognostic Index scores (P = .01). To explore the mechanism by which IL-10 may contribute to an inferior EFS, we investigated the effect of IL-10 on the JAK2 pathway and found that the IL-10/IL-10 receptor complex up-regulated JAK2 signaling. Neutralizing Ab to IL-10 inhibited constitutive and IL-10-induced JAK2/STAT3 phosphorylation. JAK2 inhibition dephosphorylated JAK2 and STAT3 and caused an inhibitory effect on phospho-JAK2-positive DLBCL cells; there was a minimal effect on phospho-JAK2-negative cells. Apoptosis induced by JAK2 inhibition was dependent on inhibition of autocrine IL-10 and c-myc expression and independent of Bcl-2 family expression. These results provide the rationale for testing JAK2 inhibitors in DLBCL patients, and indicate that serum IL-10 may be a biomarker to identify patients more likely to respond to JAK2-targeted therapy.