Maurer, Matthew J.

Background:Recent large next generation sequencing studies have redefined the genomic landscape of diffuse large B‐cell lymphoma (DLBCL). While many of the more common genetic variants, primarily mutations, have been biologically characterized, little is known about newly emerging genetic aberrations. In particular, somatic copy number alterations remain poorly studied due to the large genomic regions they cover and the number of genes involved. This, in combination with lack of remission or early relapse in a portion of DLBCL, opens new opportunities to explore yet unidentified genetic contributions to lymphomagenesis.Aims:The goal of this study was to identify variants associated with failure to achieve event free survival at 24 months (EFS24) and define their biologic significance in DLBCL.Methods:Newly diagnosed DLBCL treated with standard immunochemotherapy were included in this study (n = 246). Copy number data was generated by using the molecular inversion probe OncoScan™ FFPE Assay Kit (Affymetrix, Santa Clara, CA, USA). OncoScan OSCHP files were analyzed using Nexus Copy Number 9.0 software (Biodiscovery, El Segundo, USA). Data interpretation and copy number calling was done using the human reference genome GRCh37/hg19. Files were analyzed using the Nexus FASST2‐Segmentation algorithm, which is based on a Hidden Markov Model approach for calling genetic events. For functional analysis, SOCS6 was overexpressed and studied in GCB‐DLBCL cell lines.Results:Upon review of genomic copy number data from DLBCL cases (n = 246), loss of 18q22.1‐q23 was a significant event in our cohort (p = 0.018), is found in 11% (n = 27) of DLBCL, and is enriched in germinal center DLBCL (GCB‐DLBCL) patients (18/107, 17%, p < 0.05) compared to activated B‐cell (ABC)/non‐GCB DLBCL patients (1/93, 1%). Furthermore, GCB‐DLBCL patients with a loss of 18q22.1‐q23 were significantly more likely to fail EFS24 (50%, p < 0.05) compared to GCB‐DLBCL patients without the loss (29%). Genes located at 18q22.1‐q23 include, TMX3, DOK6 and SOCS6. SOCS family proteins have been shown to play an important role in tumor biology, although little is known about SOCS6. SOCS6 gene expression is downregulated in a variety of solid tumors and is hypermethylated in some hematological malignancies. RNASeq data from DLBCL suggest variable expression across tumors. Using a panel of GCB cell lines we found that SOCS6 expression was low to negative, and publically available cell line data suggests this region is hypermethylated. Expression of SOCS6 was higher in a panel of mantle cell lymphoma and ABC‐DLBCL cell lines and this again correlated with their cell line methylation data, where no hypermethylation was found in those cell lines. Together, this data suggests that downregulation of SOCS6 through genomic loss or hypermethylation may have biologic importance. To explore the role of SOCS6, we restored expression in GCB cell lines and immuno‐fluorescence staining suggest localization to the nucleus and cytoplasm, as previously reported in other cell types. Studies to explore the role of SOCS6 in cytokine signaling and STAT family protein regulation are ongoing.Summary/Conclusion:Using genome copy number data from 246 DLBCL, we have found that loss of 18q22.1‐q23 (p = 0.018) is associated with GCB‐DLBCL and failure to achieve EFS24. Furthermore, we have identified that SOCS6 may have clinical and biologic significance in GCB‐DLBCL.

PURPOSE In patients with diffuse large B-cell lymphoma (DLBCL), most relapses occur within the first 2 years of diagnosis. We sought to define the rate and outcome of late relapses that occurred after achieving event-free survival at 24 months (EFS24). METHODS We prospectively followed 1,324 patients with newly diagnosed DLBCL from 2002 to 2015 and treated with immunochemotherapy. Cumulative incidences of late DLBCL and indolent lymphoma relapses were analyzed as competing events. Postrelapse survival was defined as time from first relapse to death from any cause. RESULTS In 847 patients who achieved EFS24, the cumulative incidence of late relapse was 6.9% at 3 years, 9.3% at 5 years, and 10.3% at 8 years after EFS24. The incidence of DLBCL relapse was similar in patients with DLBCL alone at diagnosis (6.3% at 5 years), compared with patients with concurrent indolent lymphoma at diagnosis (5.2%; P = .46). However, the rate of indolent lymphoma relapse was higher in patients with concurrent indolent lymphoma (7.4% v 2.1% at 5 years; P < .01). In patients with DLBCL alone, the rate of DLBCL relapse was similar in the germinal center B-cell–like (GCB) (4.1% at 5 years) and non-GCB (4.0%; P = .71) subtypes, whereas the rate of indolent lymphoma relapse was higher in patients with the GCB subtype (3.9% v 0.0% at 5 years; P = .02). Postrelapse survival was inferior for patients who relapsed with DLBCL than for those who relapsed with indolent lymphoma (median 29.9 months v unreached; P < .01). CONCLUSION Patients with DLBCL with a concurrent indolent lymphoma and those with the GCB subtype had a higher rate of late relapse, owing to increased relapses with indolent lymphoma. Patients who relapsed with DLBCL had a worse prognosis than those who relapsed with indolent lymphoma.

SummaryThe diabetes mellitus (DM) drug metformin targets mechanistic/mammalian target of rapamycin and inhibits lymphoma growth in vitro. We investigated whether metformin affected outcomes of newly diagnosed diffuse large B‐cell (DLBCL, n = 869) and follicular lymphoma (FL, n = 895) patients enrolled in the Mayo component of the Molecular Epidemiology Resource cohort study between 2002 and 2015. Hazard ratios (HR) and 95% confidence intervals (CIs) adjusted for age, sex, body mass index, prognostic index and treatment were used to estimate the association of metformin exposure (No DM/No metformin; DM/No metformin; DM/Metformin) with event‐free (EFS), lymphoma‐specific (LSS) and overall (OS) survival. Compared to No DM/No metformin DLBCL patients, there was no association of DM/Metformin (n = 48; HR = 1·05, 95% CI 0·59–1·89) or DM/No metformin(n = 54; HR = 1·41, 95% CI 0·88–2·26) with EFS; results were similar for LSS and OS. Compared to No DM/No metformin FL patients, there was no association of DM/Metformin (n = 37; HR = 1·16, 95% CI 0·71–1·89) or DM/No metformin (n = 19; HR = 1·16, 95% CI 0·66–2·04) with EFS; results were similar for LSS. However, DM/Metformin was associated with inferior OS (HR = 2·17; 95% CI 1·19–3·95) compared to No DM/No metformin. In conclusion, we found no evidence that metformin use was associated with improved outcomes in newly diagnosed DLBCL and FL.

e17039 Background: Treatment strategies are needed for platinum-resistant recurrent ovarian cancer. Glucocorticoid receptor (GR) is associated with poor prognosis in ovarian cancer. GR signaling inhibits chemotherapy-induced cell death via transcriptional regulation of anti-apoptotic proteins. Non-selective (mifepristone) and selective GR antagonists (Relacorilant, Corcept Therapeutics) are under clinical development (eg. NCT02046421, NCT03776812). We hypothesized that GR antagonism would improve chemotherapy sensitivity in ovarian cancer patient-derived xenograft (PDX) models. Methods: Five PDX models were selected based on GR expression above median RNA seq levels. Tissues were transplanted into 300 female SCID-Bg mice at the Mayo Clinic. Once tumor diameter reached 0.2 cm, mice were randomized into treatment arms (2-25 mice per arm) and treated intraperitoneal (i.p): control (9% saline, CTL) on day 0 (D0), 1, 7, 8, 14, 15, 21, 22; mifepristone (MIF), 15 mg/kg D0, 1, 7, 8, 14, 15, 21, 22; relacorilant (134), 20 mg/kg D0, 1, 7, 8, 14, 15, 21, 22; carboplatin (CBDCA) at the MTD, 51 mg/kg D1, 8, 15, 22; CBDCA + MIF; CBDCA + 134. Tumor area was measured by ultrasound weekly (D0-D28), and the ratio calculated relative to D0. Tumor growth curves were compared between arms for each PDX via a linear mixed effects regression test of coincident curves. Time to progression was also evaluated and will be presented. Results: In 1/5 models (PH160), CBDCA + MIF significantly suppressed tumor growth compared to CBDCA alone (p < 0.05, Table 1). Addition of 134 to CBDCA did not suppress tumor growth compared to CBDCA alone in any model. In the 2 models with no difference of CBDCA versus CTL (PH160, PH454), addition of a GR antagonist to CBDCA suppressed tumor growth versus CTL. Conclusions: Addition of GR antagonists can improve response to chemotherapy. Work is ongoing to identify the GR transcriptional network, tumor, and host characteristics which predict responses to GR antagonists. [Table: see text]

e17038 Background: Carcinosarcomas (CS) are aggressive gynecologic malignancies defined by a biphasic tumor histology of carcinomatous and sarcomatous components. High expression of glucocorticoid receptor (GR) is associated with aggressive tumor biology in triple-negative breast, ovarian, and endometrial cancers. GR activation results in transcriptional regulation of epithelial-mesenchymal transition (EMT) genes. Therefore, we hypothesized that the sarcomatous component of Müllerian CS may be associated with relatively higher GR expression compared to the carcinomatous portion. Methods: Müllerian CSs from the University of Chicago tissue bank diagnosed from 5/19/2009 – 8/25/2014 were identified and pathology confirmed (RL). In addition, we evaluated GR expression in a mouse PDX CS model. Immunohistochemical expression of nuclear estrogen (ER), progesterone (PR), androgen (AR), and GR was quantified using the H-score. Scores between the sarcomatous and carcinomatous components were compared using a paired t-test. Results: Mean GR H-score was relatively higher in the sarcomatous vs carcinomatous component, overall (144.44 vs 38.89, P = 0.0014). Mean H-score also differed between sarcomatous and carcinomatous components for ER (3.06 vs 63.06, P = 0.016), PR (1.67 vs 47.22, P = 0.004), and AR (0 vs 2.78, P = 0.056). The significantly higher sarcomatous GR expression was replicated in IHC evaluation of the mouse PDX model. Conclusions: GR expression is significantly higher in the sarcomatous than the carcinomatous component of Müllerian CS, while ER, PR, and AR expression is significantly lower. Recent data suggest that an EMT gene signature is more prominently expressed in the sarcomatous versus carcinomatous component. We hypothesize that GR expression and activity may mediate EMT gene expression and represent a therapeutic target for CS. [Table: see text]

AbstractPredicting early clinical failure in patients with untreated follicular lymphoma (FL) is important but difficult. This study aimed to determine the incidence and patterns of extranodal (EN) and spleen disease using PET/CT, and assess their utility in predicting early clinical failure. PET/CT images from 613 cases of untreated FL (2003‐2016) were reviewed. The location and number of EN sites, patterns of bone involvement, and splenic involvement were recorded. Outcomes were assessed using event‐free survival (EFS), overall survival (OS), and early clinical failure at 24 months (EFS24). So, 49% (301/613) of patients had PET/CT‐detected EN involvement, and 28% (171/613) had spleen involvement. The presence of ≥2 EN sites, spleen, bone or soft tissue involvement all predicted failure to achieve EFS24. Presence of ≥2 EN sites and bone involvement pattern were also predictive of OS in a univariate analysis. In a multivariate analysis with FLIPI‐2 factors, spleen involvement, pattern of bone involvement, and soft tissue involvement independently predicted a lower EFS (HR 1.49 (1.11‐2.00),P= .007; HR 1.71 (1.10‐2.65),P= .017; and HR 1.67 (1.06‐2.62),P= .026, respectively). When the multivariate analysis was performed using PRIMA‐PI factors (marrow and B2M), the number of EN sites was an independent prognostic factor for inferior OS (HR 2.28;P= .05). Baseline PET/CT identifies EN involvement in nearly half of patients with untreated FL. The presence of ≥2 EN sites, bone, soft tissue, or splenic involvement predicts early clinical failure. These results, when combined with other factors, may better identify high‐risk patients and guide therapy.