The cell-cycle regulator c-Myc is essential for the formation and maintenance of germinal centers.

Germinal centers (GCs) are sites of intense B cell proliferation and are central for T cell-dependent antibody responses. However, the role of c-Myc, a key cell-cycle regulator, in this process has been questioned. Here we identified c-Myc(+) B cell subpopulations in immature and mature GCs and found, by genetic ablation of Myc, that they had indispensable roles in the formation and maintenance of GCs. The identification of these functionally critical cellular subsets has implications for human B cell lymphomagenesis, which originates mostly from GC B cells and frequently involves MYC chromosomal translocations. As these translocations are generally dependent on transcription of the recombining partner loci, the c-Myc(+) GC subpopulations may be at a particularly high risk for malignant transformation.

Safety and activity of anti-mesothelin antibody-drug conjugate anetumab ravtansine in combination with pegylated-liposomal doxorubicin in platinum-resistant ovarian cancer: multicenter, phase Ib dose escalation and expansion study.

OBJECTIVES: Anetumab ravtansine is an antibody-drug conjugate consisting of a fully human anti-mesothelin monoclonal antibody conjugated to cytotoxic maytansinoid tubulin inhibitor DM4. Mesothelin is highly expressed in ovarian cancer. This phase Ib study determines the safety, pharmacokinetics, and anti-tumor activity of anetumab ravtansine and pegylated liposomal doxorubicin in mesothelin-expressing platinum-resistant ovarian cancer. METHODS: Anetumab ravtansine (5.5 or 6.5 mg/kg) and pegylated liposomal doxorubicin (30 mg/m2) were administered intravenously every 3 weeks to 65 patients with platinum-resistant epithelial ovarian cancer. Mesothelin expression was assessed by central immunohistochemistry. Adverse events, tumor response (RECIST 1.1), and progression-free survival were determined. Biomarker samples were assessed by ELISA and next-generation sequencing. RESULTS: In dose escalation, nine patients received anetumab ravtansine across two doses (5.5 or 6.5 mg/kg). The maximum tolerated dose of anetumab ravtansine was 6.5 mg/kg every 3 weeks and no dose-limiting toxicities were observed. In dose expansion, 56 patients were treated at the maximum tolerated dose. The most common treatment-emergent adverse events of any grade were nausea (47.7%), decreased appetite (43.1%), fatigue (38.5%), diarrhea (32.3%), and corneal disorder (29.2%). In all treated patients the objective response rate was 27.7% (95% CI 17.3% to 40.2%), including one complete (1.5%) and 17 partial responses (26.2%), with median duration of response of 7.6 (95% CI 3.3 to 10.2) months and median progression-free survival of 5.0 (95% CI 3.2 to 6.0) months. In an exploratory analysis of a sub-set of patients (n=19) with high mesothelin expression who received ≤3 prior lines of systemic therapy, the objective response rate was 42.1% (95% CI 20.3% to 66.5%) with a median duration of response of 8.3 (95% CI 4.1 to 12.0) months and median progression-free survival of 8.5 (95% CI 4.0 to 11.4) months. CONCLUSIONS: Anetumab ravtansine and pegylated liposomal doxorubicin showed tolerability and promising clinical activity. These results established the dose schedule and the mesothelin-positive target population of this combination for a phase III study in platinum-resistant ovarian cancer. TRIAL REGISTRATION NUMBER: NCT02751918.

Anetumab ravtansine versus vinorelbine in patients with relapsed, mesothelin-positive malignant pleural mesothelioma (ARCS-M): a randomised, open-label phase 2 trial.

BACKGROUND: Few treatment options exist for second-line treatment of malignant pleural mesothelioma. We aimed to assess the antibody-drug conjugate anetumab ravtansine versus vinorelbine in patients with unresectable locally advanced or metastatic disease overexpressing mesothelin who had progressed on first-line platinum-pemetrexed chemotherapy with or without bevacizumab. METHODS: In this phase 2, randomised, open-label study, done at 76 hospitals in 14 countries, we enrolled adults (aged ≥18 years) with unresectable locally advanced or metastatic malignant pleural mesothelioma, an Eastern Cooperative Oncology Group performance status of 0-1, and who had progressed on first-line platinum-pemetrexed chemotherapy with or without bevacizumab. Participants were prospectively screened for mesothelin overexpression (defined as 2+ or 3+ mesothelin membrane staining intensity on at least 30% of viable tumour cells by immunohistochemistry) and were randomly assigned (2:1), using an interactive voice and web response system provided by the sponsor, to receive intravenous anetumab ravtansine (6·5 mg/kg on day 1 of each 21-day cycle) or intravenous vinorelbine (30 mg/m2 once every week) until progression, toxicity, or death. The primary endpoint was progression-free survival according to blinded central radiology review, assessed in the intention-to-treat population, with safety assessed in all participants who received any study treatment. This study is registered with ClinicalTrials.gov, NCT02610140, and is now completed. FINDINGS: Between Dec 3, 2015, and May 31, 2017, 589 patients were enrolled and 248 mesothelin-overexpressing patients were randomly allocated to the two treatment groups (166 patients were randomly assigned to receive anetumab ravtansine and 82 patients were randomly assigned to receive vinorelbine). 105 (63%) of 166 patients treated with anetumab ravtansine (median follow-up 4·0 months [IQR 1·4-5·5]) versus 43 (52%) of 82 patients treated with vinorelbine (3·9 months [1·4-5·4]) had disease progression or died (median progression-free survival 4·3 months [95% CI 4·1-5·2] vs 4·5 months [4·1-5·8]; hazard ratio 1·22 [0·85-1·74]; log-rank p=0·86). The most common grade 3 or worse adverse events were neutropenia (one [1%] of 163 patients for anetumab ravtansine vs 28 [39%] of 72 patients for vinorelbine), pneumonia (seven [4%] vs five [7%]), neutrophil count decrease (two [1%] vs 12 [17%]), and dyspnoea (nine [6%] vs three [4%]). Serious drug-related treatment-emergent adverse events occurred in 12 (7%) patients treated with anetumab ravtansine and 11 (15%) patients treated with vinorelbine. Ten (6%) treatment-emergent deaths occurred with anetumab ravtansine: pneumonia (three [2%]), dyspnoea (two [1%]), sepsis (two [1%]), atrial fibrillation (one [1%]), physical deterioration (one [1%]), hepatic failure (one [1%]), mesothelioma (one [1%]), and renal failure (one [1%]; one patient had 3 events). One (1%) treatment-emergent death occurred in the vinorelbine group (pneumonia). INTERPRETATION: Anetumab ravtansine showed a manageable safety profile and was not superior to vinorelbine. Further studies are needed to define active treatments in relapsed mesothelin-expressing malignant pleural mesothelioma. FUNDING: Bayer Healthcare Pharmaceuticals.

Biomarkers Associated With Response to Regorafenib in Patients With Hepatocellular Carcinoma.

BACKGROUND & AIMS: In a phase 3 trial (RESORCE), regorafenib increased overall survival compared with placebo in patients with hepatocellular carcinoma (HCC) previously treated with sorafenib. In an exploratory study, we analyzed plasma and tumor samples from study participants to identify genetic, microRNA (miRNA), and protein biomarkers associated with response to regorafenib. METHODS: We obtained archived tumor tissues and baseline plasma samples from patients with HCC given regorafenib in the RESORCE trial. Baseline plasma samples from 499 patients were analyzed for expression of 294 proteins (DiscoveryMAP) and plasma samples from 349 patients were analyzed for levels of 750 miRNAs (miRCURY miRNA PCR). Tumor tissues from 7 responders and 10 patients who did not respond (progressors) were analyzed by next-generation sequencing (FoundationOne). Forty-six tumor tissues were analyzed for expression patterns of 770 genes involved in oncogenic and inflammatory pathways (PanCancer Immune Profiling). Associations between plasma levels of proteins and miRNAs and response to treatment (overall survival and time to progression) were evaluated using a Cox proportional hazards model. RESULTS: Decreased baseline plasma concentrations of 5 of 266 evaluable proteins (angiopoietin 1, cystatin B, the latency-associated peptide of transforming growth factor beta 1, oxidized low-density lipoprotein receptor 1, and C-C motif chemokine ligand 3; adjusted P ≤ .05) were significantly associated with increased overall survival time after regorafenib treatment. Levels of these 5 proteins, which have roles in inflammation and/or HCC pathogenesis, were not associated with survival independently of treatment. Only 20 of 499 patients had high levels and a reduced survival time. Plasma levels of α-fetoprotein and c-MET were associated with poor outcome (overall survival) independently of regorafenib treatment only. We identified 9 plasma miRNAs (MIR30A, MIR122, MIR125B, MIR200A, MIR374B, MIR15B, MIR107, MIR320, and MIR645) whose levels significantly associated with overall survival time with regorafenib (adjusted P ≤ .05). Functional analyses of these miRNAs indicated that their expression level associated with increased overall survival of patients with tumors of the Hoshida S3 subtype. Next-generation sequencing analyses of tumor tissues revealed 49 variants in 27 oncogenes or tumor suppressor genes. Mutations in CTNNB1 were detected in 3 of 10 progressors and VEGFA amplification in 1 of 7 responders. CONCLUSION: We identified expression patterns of plasma proteins and miRNAs that associated with increased overall survival times of patients with HCC following treatment with regorafenib in the RESORCE trial. Levels of these circulating biomarkers and genetic features of tumors might be used to identify patients with HCC most likely to respond to regorafenib. ClinicalTrials.gov number NCT01774344. NCBI GEO accession numbers: mRNA data (NanoString): GSE119220; miRNA data (Exiqon): GSE119221.

Effect of HLA-DRB1 alleles and genetic variants on the development of neutralizing antibodies to interferon beta in the BEYOND and BENEFIT trials.

BACKGROUND: Treatment of multiple sclerosis (MS) with interferon ß can lead to the development of antibodies directed against interferon ß that interfere with treatment efficacy. Several observational studies have proposed different HLA alleles and genetic variants associated with the development of antibodies against interferon ß. OBJECTIVE: To validate the proposed genetic markers and to identify new markers. METHODS: Associations of genetic candidate markers with antibody presence and development were examined in a post hoc analysis in 941 patients treated with interferon ß-1b in the Betaferon® Efficacy Yielding Outcomes of a New Dose (BEYOND) and BEtaseron®/BEtaferon® in Newly Emerging multiple sclerosis For Initial Treatment (BENEFIT) prospective phase III trials. All patients were treated with interferon ß-1b for at least 6 months. In addition, a genome-wide association study was conducted to identify new genetic variants. RESULTS: We confirmed an increased risk for carriers of HLA-DRB1*04:01 (odds ratio (OR) = 3.3, p = 6.9 × 10-4) and HLA-DRB1*07:01 (OR = 1.8, p = 3.5 × 10-3) for developing neutralizing antibodies (NAbs). Several additional, previously proposed HLA alleles and genetic variants showed nominally significant associations. In the exploratory analysis, variants in the HLA region were associated with NAb development at genome-wide significance (OR = 2.6, p = 2.30 × 10-15). CONCLUSION: The contribution of HLA alleles and HLA-associated single-nucleotide polymorphisms (SNPs) to the development and titer of antibodies against interferon ß was confirmed in the combined analysis of two multi-national, multi-center studies.

Canonical NF-κB signaling is uniquely required for the long-term persistence of functional mature B cells.

Although canonical NF-κB signaling is crucial to generate a normal mature B-cell compartment, its role in the persistence of resting mature B cells is controversial. To resolve this conflict, we ablated NF-κB essential modulator (NEMO) and IκB kinase 2 (IKK2), two essential mediators of the canonical pathway, either early on in B-cell development or specifically in mature B cells. Early ablation severely inhibited the generation of all mature B-cell subsets, but follicular B-cell numbers could be largely rescued by ectopic expression of B-cell lymphoma 2 (Bcl2), despite a persisting block at the transitional stage. Marginal zone (MZ) B and B1 cells were not rescued, indicating a possible role of canonical NF-κB signals beyond the control of cell survival in these subsets. When canonical NF-κB signaling was ablated specifically in mature B cells, the differentiation and/or persistence of MZ B cells was still abrogated, but follicular B-cell numbers were only mildly affected. However, the mutant cells exhibited increased turnover as well as functional deficiencies upon activation, suggesting that canonical NF-κB signals contribute to their long-term persistence and functional fitness.

Mapping of transcription factor motifs in active chromatin identifies IRF5 as key regulator in classical Hodgkin lymphoma.

Deregulated transcription factor (TF) activities are commonly observed in hematopoietic malignancies. Understanding tumorigenesis therefore requires determining the function and hierarchical role of individual TFs. To identify TFs central to lymphomagenesis, we identified lymphoma type-specific accessible chromatin by global mapping of DNaseI hypersensitive sites and analyzed enriched TF-binding motifs in these regions. Applying this unbiased approach to classical Hodgkin lymphoma (HL), a common B-cell-derived lymphoma with a complex pattern of deregulated TFs, we discovered interferon regulatory factor (IRF) sites among the top enriched motifs. High-level expression of the proinflammatory TF IRF5 was specific to HL cells and crucial for their survival. Furthermore, IRF5 initiated a regulatory cascade in human non-Hodgkin B-cell lines and primary murine B cells by inducing the TF AP-1 and cooperating with NF-κB to activate essential characteristic features of HL. Our strategy efficiently identified a lymphoma type-specific key regulator and uncovered a tumor promoting role of IRF5.

AKT1 (E17K) mutation profiling in breast cancer: prevalence, concurrent oncogenic alterations, and blood-based detection.

BACKGROUND: The single hotspot mutation AKT1 [G49A:E17K] has been described in several cancers, with the highest incidence observed in breast cancer. However, its precise role in disease etiology remains unknown. METHODS: We analyzed more than 600 breast cancer tumor samples and circulating tumor DNA for AKT1 (E17K) and alterations in other cancer-associated genes using Beads, Emulsions, Amplification, and Magnetics digital polymerase chain reaction technology and targeted exome sequencing. RESULTS: Overall AKT1 (E17K) mutation prevalence was 6.3 % and not correlated with age or menopausal stage. AKT1 (E17K) mutation frequency tended to be lower in patients with grade 3 disease (1.9 %) compared with those with grade 1 (11.1 %) or grade 2 (6 %) disease. In two cohorts of patients with advanced metastatic disease, 98.0 % (n = 50) and 97.1 % (n = 35) concordance was obtained between tissue and blood samples for the AKT1 (E17K) mutation, and mutation capture rates of 66.7 % (2/3) and 85.7 % (6/7) in blood versus tissue samples were observed. Although AKT1-mutant tumor specimens were often found to harbor concurrent alterations in other driver genes, a subset of specimens harboring AKT1 (E17K) as the only known driver alteration was also identified. Initial follow-up survival data suggest that AKT1 (E17K) could be associated with increased mortality. These findings warrant additional long-term follow-up. CONCLUSIONS: The data suggest that AKT1 (E17K) is the most likely disease driver in certain breast cancer patients. Blood-based mutation detection is achievable in advanced-stage disease. These findings underpin the need for a further enhanced-precision medicine paradigm in the treatment of breast cancer.

On the Application of Artificial Intelligence/Machine Learning (AI/ML) in Late-Stage Clinical Development.

Whereas AI/ML methods were considered experimental tools in clinical development for some time, nowadays they are widely available. However, stakeholders in the health care industry still need to answer the question which role these methods can realistically play and what standards should be adhered to. Clinical research in late-stage clinical development has particular requirements in terms of robustness, transparency and traceability. These standards should also be adhered to when applying AI/ML methods. Currently there is some formal regulatory guidance available, but this is more directed at settings where a device or medical software is investigated. Here we focus on the application of AI/ML methods in late-stage clinical drug development, i.e. in a setting where currently less guidance is available. This is done via first summarizing available regulatory guidance and work done by regulatory statisticians followed by the presentation of an industry application where the influence of extensive sets of baseline characteristics on the treatment effect can be investigated by applying ML-methods in a standardized manner with intuitive graphical displays leveraging explainable AI methods. The paper aims at stimulating discussions on the role such analyses can play in general rather than advocating for a particular AI/ML-method or indication where such methods could be meaningful.

Aberrant Expression of and Cell Death Induction by Engagement of the MHC-II Chaperone CD74 in Anaplastic Large Cell Lymphoma (ALCL).

In 50-60% of cases, systemic anaplastic large cell lymphoma (ALCL) is characterized by the t(2;5)(p23;q35) or one of its variants, considered to be causative for anaplastic lymphoma kinase (ALK)-positive (ALK+) ALCL. Key pathogenic events in ALK-negative (ALK-) ALCL are less well defined. We have previously shown that deregulation of oncogenic genes surrounding the chromosomal breakpoints on 2p and 5q is a unifying feature of both ALK+ and ALK- ALCL and predisposes for occurrence of t(2;5). Here, we report that the invariant chain of the MHC-II complex CD74 or li, which is encoded on 5q32, can act as signaling molecule, and whose expression in lymphoid cells is usually restricted to B cells, is aberrantly expressed in T cell-derived ALCL. Accordingly, ALCL shows an altered DNA methylation pattern of the CD74 locus compared to benign T cells. Functionally, CD74 ligation induces cell death of ALCL cells. Furthermore, CD74 engagement enhances the cytotoxic effects of conventional chemotherapeutics in ALCL cell lines, as well as the action of the ALK-inhibitor crizotinib in ALK+ ALCL or of CD95 death-receptor signaling in ALK- ALCL. Additionally, a subset of ALCL cases expresses the proto-oncogene MET, which can form signaling complexes together with CD74. Finally, we demonstrate that the CD74-targeting antibody-drug conjugate STRO-001 efficiently and specifically kills CD74-positive ALCL cell lines in vitro. Taken together, these findings enabled us to demonstrate aberrant CD74-expression in ALCL cells, which might serve as tool for the development of new treatment strategies for this lymphoma entity.

On-Target Pharmacodynamic Activity of the PI3K Inhibitor Copanlisib in Paired Biopsies from Patients with Malignant Lymphoma and Advanced Solid Tumors.

The PI3K inhibitor copanlisib has efficacy and manageable safety in patients with indolent lymphoma and solid tumors. Pharmacodynamic effects relative to copanlisib dose and plasma exposure were evaluated. Patients with lymphoma or solid tumors received copanlisib 0.4 or 0.8 mg/kg on days 1, 8, and 15 of a 28-day cycle. Primary variables were maximum changes in phosphorylated AKT (pAKT) levels in platelet-rich plasma (PRP) and plasma glucose. Other evaluations included PI3K signaling markers and T-lymphocytes in paired tumor biopsies, the relationship between estimated plasma exposure and pharmacodynamic markers, response, and safety. Sixty-three patients received copanlisib. PRP pAKT levels showed sustained reductions from baseline following copanlisib [median inhibition: 0.4 mg/kg, 73.8% (range -94.9 to 144.0); 0.8 mg/kg, 79.6% (range -96.0 to 408.0)]. Tumor pAKT was reduced versus baseline with copanlisib 0.8 mg/kg in paired biopsy samples (P < 0.05). Dose-related transient plasma glucose elevations were observed. Estimated copanlisib plasma exposure significantly correlated with changes in plasma pAKT and glucose metabolism markers. There were two complete responses and six partial responses; seven of eight responders received copanlisib 0.8 mg/kg. Adverse events (all grade) included hyperglycemia (52.4%), fatigue (46.0%), and hypertension (41.3%). Copanlisib demonstrated dose-dependent pharmacodynamic evidence of target engagement and PI3K pathway modulation/inhibition in tumor and immune cells. Results support the use of copanlisib 0.8 mg/kg (or flat-dose equivalent of 60 mg) in solid tumors and lymphoma, and provide a biomarker hypothesis for studies of copanlisib combined with immune checkpoint inhibitors (NCT03711058).

Phosphatidylinositol 3-Kinase Inhibition by Copanlisib in Relapsed or Refractory Indolent Lymphoma.

Purpose Phosphatidylinositol 3-kinase (PI3K) signaling is critical for the proliferation and survival of malignant B cells. Copanlisib, a pan-class I PI3K inhibitor with predominant activity against PI3K-α and -δ isoforms, has demonstrated efficacy and a manageable safety profile in patients with indolent lymphoma. Patients and Methods In this phase II study, 142 patients with relapsed or refractory indolent lymphoma after two or more lines of therapy were enrolled to receive copanlisib 60 mg intravenously on days 1, 8, and 15 of a 28-day cycle. The primary end point was objective response rate; secondary end points included duration of response, progression-free survival, and overall survival. In addition, safety and gene expression were evaluated. Results Median age was 63 years (range, 25 to 82 years), and patients had received a median of three (range, two to nine) prior regimens. The objective response rate was 59% (84 of 142 patients); 12% of patients achieved a complete response. Median time to response was 53 days. Median duration of response was 22.6 months, median progression-free survival was 11.2 months, and median overall survival had not yet been reached. The most frequent treatment-emergent adverse events were transient hyperglycemia (all grades, 50%; grade 3 or 4, 41%) and transient hypertension (all grades, 30%; grade 3, 24%). Other grade ≥3 events included decreased neutrophil count (24%) and lung infection (15%). High response rates to copanlisib were associated with high expression of PI3K/B-cell receptor signaling pathway genes. Conclusion PI3K-α and -δ inhibition by copanlisib demonstrated significant efficacy and a manageable safety profile in heavily pretreated patients with relapsed or refractory indolent lymphoma.

Association of Vitamin D Levels With Multiple Sclerosis Activity and Progression in Patients Receiving Interferon Beta-1b.

IMPORTANCE: Low serum 25-hydroxyvitamin D (25[OH]D) levels are associated with an increased risk of multiple sclerosis (MS) as well as with increased disease activity and rate of progression in clinically isolated syndromes and early MS. OBJECTIVE: To assess the association between 25(OH)D and disease course and prognosis in patients with relapsing-remitting MS treated with interferon beta-1b. DESIGN, SETTING, AND PARTICIPANTS: We conducted a prospective cohort study assessing 25(OH)D levels and subsequent MS disease course and progression characterized by magnetic resonance imaging (MRI) and clinical end points. The study took place between November 2003 and June 2005; data analysis was performed between June 2013 and December 2014. The study was conducted among participants in the Betaferon Efficacy Yielding Outcomes of a New Dose (BEYOND) study, a large, phase 3, prospective, multicenter, blinded, randomized clinical trial. Patients were monitored for at least 2 years. Clinic visits were scheduled every 3 months, and MRI was performed at baseline and annually thereafter. Eligible patients included 1482 participants randomized to receive 250 µg or 500 µg of interferon-1b with at least 2 measurements of 25(OH)D obtained 6 months apart. EXPOSURES: Serum 25(OH)D measurements were performed at baseline, 6 months, and 12 months. MAIN OUTCOMES AND MEASURES: Main outcomes included cumulative number of new active lesions (T2 lesions and gadolinium acetate-enhancing lesions), change in normalized brain volume, relapse rate, and progression determined by the Expanded Disability Status Scale (EDSS). Statistical analyses were adjusted for age, sex, randomized treatment, region, disease duration, and baseline EDSS score. RESULTS: Overall, average 25(OH)D levels in 1482 patients were significantly inversely correlated with the cumulative number of new active lesions between baseline and the last MRI, with a 50.0-nmol/L increase in serum 25(OH)D levels associated with a 31% lower rate of new lesions (relative rate [RR], 0.69; 95% CI, 0.55-0.86; P = .001). The lowest rate of new lesions was observed among patients with 25(OH)D levels greater than 100.0 nmol/L (RR, 0.53; 95% CI, 0.37-0.78; P = .002). No significant associations were found between 25(OH)D levels and change in brain volume, relapse rates, or EDSS scores. Results were consistent following adjustment for HLA-DRB1*15 or vitamin D-binding protein status. CONCLUSIONS AND RELEVANCE: Among patients with MS treated with interferon beta-1b, higher 25(OH)D levels were associated with lower rates of MS activity observed on MRI. Results for brain atrophy and clinical progression were more equivocal.

An oncogenic role for alternative NF-κB signaling in DLBCL revealed upon deregulated BCL6 expression.

Diffuse large B cell lymphoma (DLBCL) is a complex disease comprising diverse subtypes and genetic profiles. Possibly because of the prevalence of genetic alterations activating canonical NF-κB activity, a role for oncogenic lesions that activate the alternative NF-κB pathway in DLBCL has remained elusive. Here, we show that deletion/mutation of TRAF3, a negative regulator of the alternative NF-κB pathway, occurs in ∼15% of DLBCLs and that it often coexists with BCL6 translocation, which prevents terminal B cell differentiation. Accordingly, in a mouse model constitutive activation of the alternative NF-κB pathway cooperates with BCL6 deregulation in DLBCL development. This work demonstrates a key oncogenic role for the alternative NF-κB pathway in DLBCL development.

Molecular mechanism underlying the impact of vitamin D on disease activity of MS.

OBJECTIVE: Some previous studies suggest modest to strong effects of 25-hydroxyvitamin D (25(OH)D) on multiple sclerosis (MS) activity. The objective of this study was to explore the mechanistic rationale that may explain potential clinical effects of 25(OH)D. METHODS: This study measured serum 25(OH)D levels and global gene expression profiles over a course of up to 2 years in patients starting treatment with interferon beta-1b (IFNB-1b) after a clinically isolated syndrome. MS disease activity was assessed by the number of gadolinium-enhancing lesions present on repeated magnetic resonance imaging (MRIs). RESULTS: The number of gadolinium-enhancing lesions was highly significantly associated with 25(OH)D levels. Conducting various systems-level analyses on the molecular level, multiple lines of evidence indicated that 25(OH)D regulates expression dynamics of a large gene-gene interaction system which primarily regulates immune modulatory processes modulating MS activity. The vitamin D response element was significantly enriched in this system, indicating a direct regulation of this gene interaction network through the vitamin D receptor. With increasing 25(OH)D levels, resulting regulation of this system was associated with a decrease in MS activity. Within the complex network of genes that are regulated by 25(OH)D, well-described targets of IFNB-1b and a regulator of sphingosine-1-phosphate bioavailability were found. The 25(OH)D effects on MS activity were additively enhanced by IFNB-1b. INTERPRETATION: Here, we provide mechanistic evidence that an unbalanced 25(OH)D gene expression system may affect MS activity. Our findings support a potential benefit of monitoring and managing vitamin D levels (e.g., through supplementation) in early MS patients treated with IFN-beta-1b.

Vitamin D as an early predictor of multiple sclerosis activity and progression.

IMPORTANCE: It remains unclear whether vitamin D insufficiency, which is common in individuals with multiple sclerosis (MS), has an adverse effect on MS outcomes. OBJECTIVES: To determine whether serum concentrations of 25-hydroxyvitamin D (25[OH]D), a marker of vitamin D status, predict disease activity and prognosis in patients with a first event suggestive of MS (clinically isolated syndrome). DESIGN, SETTING, AND PARTICIPANTS: The Betaferon/Betaseron in Newly Emerging multiple sclerosis For Initial Treatment study was a randomized trial originally designed to evaluate the impact of early vs delayed interferon beta-1b treatment in patients with clinically isolated syndrome. Serum 25(OH)D concentrations were measured at baseline and 6, 12, and 24 months. A total of 465 of the 468 patients randomized had at least 1 25(OH)D measurement, and 334 patients had them at both the 6- and 12-month (seasonally asynchronous) measurements. Patients were followed up for 5 years clinically and by magnetic resonance imaging. MAIN OUTCOMES AND MEASURES: New active lesions, increased T2 lesion volume, and brain volume on magnetic resonance imaging, as well as MS relapses and disability (Expanded Disability Status Scale score). RESULTS: Higher 25(OH)D levels predicted reduced MS activity and a slower rate of progression. A 50-nmol/L (20-ng/mL) increment in average serum 25(OH)D levels within the first 12 months predicted a 57% lower rate of new active lesions (P < .001), 57% lower relapse rate (P = .03), 25% lower yearly increase in T2 lesion volume (P < .001), and 0.41% lower yearly loss in brain volume (P = .07) from months 12 to 60. Similar associations were found between 25(OH)D measured up to 12 months and MS activity or progression from months 24 to 60. In analyses using dichotomous 25(OH)D levels, values greater than or equal to 50 nmol/L (20 ng/mL) at up to 12 months predicted lower disability (Expanded Disability Status Scale score, -0.17; P = .004) during the subsequent 4 years. CONCLUSIONS AND RELEVANCE: Among patients with MS mainly treated with interferon beta-1b, low 25(OH)D levels early in the disease course are a strong risk factor for long-term MS activity and progression.

Structural insights into the mechanism of GTPase activation in the GIMAP family.

GTPases of immunity-associated proteins (GIMAPs) are regulators of lymphocyte survival and homeostasis. We previously determined the structural basis of GTP-dependent GIMAP2 scaffold formation on lipid droplets. To understand how its GTP hydrolysis is activated, we screened for other GIMAPs on lipid droplets and identified GIMAP7. In contrast to GIMAP2, GIMAP7 displayed dimerization-stimulated GTP hydrolysis. The crystal structure of GTP-bound GIMAP7 showed a homodimer that assembled via the G domains, with the helical extensions protruding in opposite directions. We identified a catalytic arginine that is supplied to the opposing monomer to stimulate GTP hydrolysis. GIMAP7 also stimulated GTP hydrolysis by GIMAP2 via an analogous mechanism. Finally, we found GIMAP2 and GIMAP7 expression differentially regulated in several human T cell lymphoma lines. Our findings suggest that GTPase activity in the GIMAP family is controlled by homo- and heterodimerization. This may have implications for the differential roles of some GIMAPs in lymphocyte survival.

Synergy between PI3K signaling and MYC in Burkitt lymphomagenesis.

In Burkitt lymphoma (BL), a germinal center B-cell-derived tumor, the pro-apoptotic properties of c-MYC must be counterbalanced. Predicting that survival signals would be delivered by phosphoinositide-3-kinase (PI3K), a major survival determinant in mature B cells, we indeed found that combining constitutive c-MYC expression and PI3K activity in germinal center B cells of the mouse led to BL-like tumors, which fully phenocopy human BL with regard to histology, surface and other markers, and gene expression profile. The tumors also accumulate tertiary mutational events, some of which are recurrent in the human disease. These results and our finding of recurrent PI3K pathway activation in human BL indicate that deregulated c-MYC and PI3K activity cooperate in BL pathogenesis.

Genomic loss of the putative tumor suppressor gene E2A in human lymphoma.

The transcription factor E2A is essential for lymphocyte development. In this study, we describe a recurrent E2A gene deletion in at least 70% of patients with Sézary syndrome (SS), a subtype of T cell lymphoma. Loss of E2A results in enhanced proliferation and cell cycle progression via derepression of the protooncogene MYC and the cell cycle regulator CDK6. Furthermore, by examining the gene expression profile of SS cells after restoration of E2A expression, we identify several E2A-regulated genes that interfere with oncogenic signaling pathways, including the Ras pathway. Several of these genes are down-regulated or lost in primary SS tumor cells. These data demonstrate a tumor suppressor function of E2A in human lymphoid cells and could help to develop new treatment strategies for human lymphomas with altered E2A activity.