Citations

Abstract MYC amplification (amp) is a marker of poor prognosis in many non-hematologic malignancies. While MYC translocations in B cell lymphoma (BCL) have been extensively studied, little is known about the significance of MYC amp. Recent studies describe increased MYC copy numbers (3-10 copies/cell) to be associated with more aggressive BCL. The WHO 2017 does not include MYC amp in the definition of high-grade BCL (HGBCL) with MYC and BCL2 and/or BCL6 rearrangement ("double-hit lymphoma", DHL). However, it also states that high-level MYC amp occurring together with a MYC rearrangement, and concurrent with BCL2 rearrangement likely has a similar clinical impact as classic DHL. Although increased MYC copy number is commonly identified by routine fluorescence in situ hybridization (FISH) testing in BCL, the experience of our large cytogenetics reference laboratory suggests that high-level MYC amp, defined as uncountable MYC signals, is far less common. Therefore, we sought to characterize the clinical, pathologic and cytogenetic features of patients with BCL showing high-level MYC amp. The Mayo Clinic cytogenetic database was retrospectively reviewed for all cases of BCL with high-level MYC amp seen by FISH from January 2010 - February 2018. All FISH studies reported as MYC amp were re-reviewed by a cytogeneticist to verify the level of amp and the MYC probes involved. Pathology was reviewed by two independent hematopathologists. Clinical information was collected through chart review. Survival analysis was performed using Kaplan-Meier curves and the Wilcoxon rank-sum test. FISH analysis for MYC aberrations identified 44/9715 (0.45%) cases with high-level MYC amp. Of cases with available H&E, the most common morphology was diffuse large BCL (DLBCL) (82%; 28/34), followed by HGBCL (15%; 5/34) and plasmablastic BCL (3%; 1/34). Hans cell of origin (COO) algorithm immunohistochemistry (IHC) identified 21/25 (84%) germinal center B-cell-like (GCB), and 4/25 (16%) non-GCB cases. 21/27 (78%) cases were BCL2+ by IHC. MYC+ by IHC was ≥40% in 21/28 (75%) and <40% in 7/28 (25%) cases. 9/17 (53%) were "double expressers" (DEL) by IHC. MYC amp probe signals appeared in a cloud-like distribution (CLD) in 31 (70%) or in a single homogenous staining region (HSR) in 13 (30%) [Figure 1A]. Among 38 cases with amp in a MYC break-apart probe, 21 (55%) had amp of 5' alone, 15 (40%) of intact and 2 (5%) of the 3' probe alone. 7/44 (16%) had MYC translocations (5 IGH; 2 non-IGH). BCL2 rearrangement was seen in 15/39 (38%) cases, and BCL6 rearrangement in 3/36 (8%). Only 2/44 (4%) cases met the current WHO 2017 definition of DHL. Clinical data was available for 20 cases. Median age at diagnosis was 64.5 (range 25-88) years with M:F of 1.5:1. Only 1/14 (7%) had bone marrow while 16/18 (88.8%) had other extranodal sites of involvement (8 gastrointestinal). The clinical presentation was heterogeneous: 13 de novo, 3 post-transplant, 3 transformed from low grade and 1 mediastinal BCL. 9/14 had an elevated LDH, median 387 (225 - 2063) U/L. R-CHOP was the most common first line therapy in 12/17 (70%). At median follow-up of 18.2 (range 0.4 - 88.9) months, 9 patients had died, 3 were in relapse and 8 remained in first complete remission. Lymphoma relapse/progression was the most common cause of death in 7/9 (78%). The median overall survival (OS) was 29.3 months [Figure 1B]. There was no statistically significant difference in OS by morphologic classification (DLBCL vs HGBCL, p=0.6), double expresser (Yes/No, p=0.19), COO (GCB vs non-GCB, p=0.08), MYC amp pattern (HSR vs CLD, p=0.48), MYC amp probe (3' vs 5' vs intact, p=0.31), MYC rearrangement (Yes/No, p=0.1), or MYC amp with concurrent BCL2/BCL6 rearrangement (Yes/No ,p=0.2). To our knowledge, this is the first study to characterize the clinical, pathologic and cytogenetic features of BCL with strictly-defined high level MYC amp identified by FISH. The 5' signal alone, or the intact MYC probe are most frequently amplified, and two distinct patterns of amp can be seen. Predominant extra nodal involvement is an important clinical observation. These cases are usually DLBCL, GCB type, and infrequently have concurrent MYC/BCL2/BCL6 rearrangement. Our study suggests that BCL with high-level MYC amp may have an aggressive disease course regardless of MYC, BCL2 and BCL6 gene rearrangement status. A larger series is necessary to further understand the clinical significance of high-level MYC amp in BCL. Figure 1. Figure 1. Disclosures No relevant conflicts of interest to declare.

Abstract Abstract 1845 Inflammation is a driving factor in the pathogenesis of many cancers including multiple myeloma (MM). The active role that cytokines play, IL-1β in particular, during the early stages of MM has been extensively characterized. Myeloma is a plasma cell tumor whose early stages are characterized by cytokine dependent growth, predominantly driven by IL-6. We have demonstrated that IL-1β is a key inducer of IL-6 expressed by bone marrow stromal cells in a paracrine fashion during the progression of multiple myeloma from smoldering myeloma (SMM) to active disease (Mayo Clinic Proc 84:114 (Feb. 2009)). Elevated ATP levels have been documented in vivo in tumor micro-environments and is a potential contributing factor to IL-1β induced inflammation. The P2X7 receptor (P2X7R) is an ATP-gated ion channel expressed by cells of the hematopoetic lineage that has been shown to play a critical role in IL-1b processing and secretion. We investigated the role this receptor may have in the release of IL-1β in the bone marrow microenvironment using bone marrow samples from both chemotherapy treated and untreated patients. Myeloma cell lines were evaluated by RT-PCR for the expression of P2X7R mRNA. Expression was detected and confirmed by sequencing in ANBL-6, MM1.S, U266, RPMI-8226 and KAS-6/1 and was comparable to U937, a previously characterized P2X7R positive cell line. A newly derived plasmacytoma cell line, PCYT3, showed very low levels of message expression. The ability of ATP, the P2X7R agonist, to trigger the processing and release of IL-1β by activation of the P2X7 channel was studied using KAS-Pro, a myeloma cell line stably transfected with a pro- IL-1β gene. IL-1β, measured by ELISA, was released in a dose dependent fashion in response to increasing amounts of ATP ranging from.6mM to 5mM. Four P2X7R specific antagonists were tested for their effect on ATP stimulated IL- 1β release from KAS-Pro; all 4 compounds demonstrated inhibition in a dose dependent manner with varying degrees of potency correlating with P2X7R inhibition. In addition fresh patient samples (8 MGUS/7SMM/9 newly diagnosed MM as well as 12 Treated MM) were evaluated for receptor expression and function. All stages of disease expressed the receptor by RT-PCR. Analysis of samples from all stages of MM, as measured directly by IL-1β ELISA as well as indirectly by measurement of IL-1β induced IL-6 production from normal bone marrow stromal cells, showed functional receptor activation in response to ATP stimulation. IL-6 production detected from MGUS patient samples had a mean result of 2,253 pg/ml, the mean for SMM was 5,495 pg/ml, MM were 6,875 pg/ml while treated MM samples showed a mean result of 15,219 pg/m. Greater than 90% inhibition of IL-1β release by the P2X7R antagonists was seen for all patients who demonstrated a positive ATP induced IL-1β release (see figure). We observed a greater than 2 fold increase in IL-1β release between the treated MM samples and the newly diagnosed MM samples, suggesting a chemotherapy induced inflammation process may be ongoing in these patients. These results confirm the activity of functional P2X7 receptors on myeloma cell lines and in fresh patient samples and suggest a role for the use of P2X7 receptor antagonists in the therapy of myeloma, particularly in patients undergoing chemotherapy. Disclosures: Hromockyj: Pfizer Corporation: Employment. Meyer:Pfizer Corporation: Employment.

Abstract Abstract 39 Three randomized trials have previously reported a progression-free survival (PFS) advantage for patients receiving thalidomide (T) maintenance post ASCT in MM. Two trials reported an overall survival (OS) advantage but the largest trial reported shows no OS advantage and in very high risk MM the use of T was deleterious. Recent trial reports demonstrate a PFS but not yet an OS advantage for patients receiving maintenance lenalidomide. We report results of NCIC CTG MY.10 which compared treatment with T (200 mg daily) and prednisone (50 mg alternate days) (T/P) until progression versus observation alone when used as maintenance therapy following ASCT. Importantly, OS was the 1ry endpoint of this study, 2ry endpoints were PFS, quality of life (QoL), toxicity, and the incidence of venous thromboembolism events (VTE). Eligibility: Patients with MM who had ASCT within 1 year of beginning initial treatment for their disease. Patients were randomized 60–100 days post ASCT and had no other medical condition precluding long term use of T/P. Results: 332 patients were enrolled. Median age was 58 years and the arms were balanced. Patients were stratified by age (<60 or >60), and CR status post transplant. Median follow up is 4 years. Only 14% of patients were in CR post transplant. 111 patients died (50 versus 61 in T/P vs. observation). The median OS was 5 years for observation, and has not yet been reached for T/P, however T/P maintenance therapy did not significantly prolong OS: p = 0.18, HR of maintenance vs. observation 0.77 (95% CI 0.53–1.13). The 4 year survival rate was 68% for T/P and 60% for observation. Age and response to transplant had no significant association with OS (p=0.21), while higher disease stage was associated with shorter OS (p=0.03). The median PFS was 28 months for T/P versus 17 months for observation: p<0.0001, HR of T/P vs. observation 0.56 (95% CI 0.43 – 0.73). The 4 year PFS rate was 32% for T/P treated patients versus 14% for patients on observation. At relapse, treatment by arm (T/P vs observation) included lenalidomide (39 vs 34%), T (13 vs 22%) or bortezomib (50 versus 46%). Non hematologic toxicities were seen in more patients with treatment (Grade 3: 92% T/P vs 49% observation, grade 4: 16% vs 7%). Common toxicities of all grades that were significantly higher in T/P treated patients included hyperglycemia, edema, hypertension, fatigue, Cushingoid appearance, constipation, mouth dryness, dyspepsia, anxiety, memory loss, sensory neuropathy, tremor, blurred vision, depressed consciousness, cataracts, dyspnea and bruising. 7% of patients on maintenance T/P developed a VTE in the absence of prophylaxis versus 0% on observation. NCIC CTG standardized response analysis was use to compare QoL data between the 2 treatment arms. Overall, patients on T/P had worse QoL specifically in physical (p=0.07), role (p=0.08), cognitive (p = 0.01) and global (p=0.06) domains, and worse symptoms with dyspnea (p = 0.0007), constipation (p<0.0001), thirst (p=0.003), swelling in leg (p=0.03), numbness (p=0.02), dry mouth (p<0.0001), and balance problems (p<0.0001). However, patients on T/P reported improvement in appetite (p 0.02), and sleep (p=0.04). Conclusions: T/P maintenance did not improve overall survival, the primary objective of this trial, although a trend in favor of T/P was seen. In contrast, PFS was significantly improved in the T/P arm while toxicity was demonstrably increased and quality of life diminished. Disclosures: Stewart: Millennium: Consultancy; Celgene: Honoraria. Trudel:Celgene: Honoraria. Bahlis:Celgene: Honoraria, Research Funding, Speakers Bureau. White:Celgene: Honoraria, Research Funding. Meyer:Celgene: Honoraria.

AimsThe aims of this study were to review our 5‐year experience with clinical FISH testing for TP63 rearrangements using both TP63 break‐apart (BAP) and TBL1XR1/TP63 dual‐fusion (D‐FISH) probes to evaluate the frequency of TP63 rearrangements and the distribution of TBL1XR1 vs. alternate partner loci, and to assess whether both probe sets are necessary in all cases undergoing FISH testing.Methods and resultsA retrospective review of the Mayo Clinic cytogenetic database identified 470 patients evaluated by FISH testing for TP63 rearrangements in formalin‐fixed paraffin‐embedded (FFPE) tissue using both BAP and D‐FISH probes. Of these, 25 (5.3%) had TP63 rearrangements. All samples were being investigated for anaplastic large‐cell lymphoma or other T cell lymphoma subtypes. A TBL1XR1 partner was identified by D‐FISH in 12 (48%) of 25 cases. All cases positive by TBL1XR1/TP63 D‐FISH were also positive by TP63 BAP FISH.ConclusionThis is the largest series of TP63 rearrangements to date. The frequency of positive results among cases referred to a large reference laboratory for TP63 FISH testing was 5.3%. Approximately half of TP63 rearrangements have a TBL1XR1 partner. TP63 BAP FISH testing is sufficient for up‐front testing of FFPE tissue samples. However, because of the genomic proximity of the TP63 and TBL1XR1 loci, we recommend reflex TBL1XR1/TP63 D‐FISH testing in positive and equivocal cases.

AbstractObjectivesMyeloid sarcoma with CBFB-MYH11 fusion may be enriched in abdominal sites. The clinicopathologic features of 11 cases are reported.MethodsWe collected clinical features, morphology, immunophenotype, and bone marrow (BM) involvement of myeloid sarcoma cases with CBFB-MYH11 fusion.ResultsEleven of 29 total myeloid sarcoma cases were CBFB-MYH11 positive and all 11 involved abdominal sites. The blastic infiltrate was associated with eosinophils in four of 11 cases and plasmacytoid dendritic cell (pDC) nodules in four of six cases. CD34, CD117, and myeloperoxidase were expressed in eight of nine, 10 of 10, and 10 of 10 cases, respectively. Ten of 10 cases showed no BM involvement.ConclusionsOur current series, combined with a literature review, identifies a compelling series of 31 (94%) of 33 cases of myeloid sarcoma with CBFB-MYH11 fusion showing a marked predilection for abdominal sites. In addition, the lack of obvious associated eosinophils, presence of pDC nodules, and lack of concurrent BM involvement suggest that “myeloid sarcoma with CBFB-MYH11 fusion” may represent a unique phenomenon.

Abstract Hepatocellular carcinoma (HCC) has emerged as a major cause of cancer deaths globally. The landscape of systemic therapy has recently changed, with six additional systemic agents either approved or awaiting approval for advanced stage HCC. While these agents have the potential to improve outcomes, a survival increase of 2–5 months remains poor and falls short of what has been achieved in many other solid tumor types. The roles of genomics, underlying cirrhosis, and optimal use of treatment strategies that include radiation, liver transplantation, and surgery remain unanswered. Here, we discuss new treatment opportunities, controversies, and future directions in managing HCC.

Abstract Background Previous studies of the prognostic importance of FOXO1 fusion status in patients with rhabdomyosarcoma (RMS) have had conflicting results. We re‐examined risk stratification by adding FOXO1 status to traditional clinical prognostic factors in children with localized or metastatic RMS. Methods Data from six COG clinical trials (D9602, D9802, D9803, ARST0331, ARTS0431, ARST0531; two studies each for low‐, intermediate‐ and high‐risk patients) accruing previously untreated patients with RMS from 1997 to 2013 yielded 1727 evaluable patients. Survival tree regression for event‐free survival (EFS) was conducted to recursively select prognostic factors for branching and split. Factors included were age, FOXO1, clinical group, histology, nodal status, number of metastatic sites, primary site, sex, tumor size, and presence of metastases in bone/bone marrow, soft tissue, effusions, lung, distant lymph nodes, and other sites. Definition and outcome of the proposed risk groups were compared to existing systems and cross‐validated results. Results The 5‐year EFS and overall survival (OS) for evaluable patients were 69% and 79%, respectively. Extent of disease (localized versus metastatic) was the first split (EFS 73% vs 30%; OS 84% vs. 42%). FOXO1 status (positive vs negative) was significant in the second split both for localized (EFS 52% vs 78%; OS 65% vs 88%) and metastatic disease (EFS 6% vs 46%; OS 19% vs 58%). Conclusions After metastatic status, FOXO1 status is the most important prognostic factor in patients with RMS and improves risk stratification of patients with localized RMS. Our findings support incorporation of FOXO1 status in risk stratified clinical trials.