Pearce, Kathryn E.

Background: Multiple myeloma (MM) is an incurable plasma cell malignancy and genetic abnormalities contribute to disease heterogeneity and outcome. Primary abnormalities, namely recurrent immunoglobulin (Ig) heavy chain translocations and hyperdiploidy, occur early in disease course. Secondary events, such as MYC abnormalities occur upon progression. Earlier studies showed MYC abnormalities detected by FISH or by capture sequencing were independently associated with poor outcome (Walker, et al., BCJ, 2014), while recent studies using WGS did not support this finding (excluding MYC/IGL) (Mikulasova, et al. Haematologica, 2020; Misund, et al. Leukemia, 2020). We hypothesize these discrepancies are due to differences in methods and sensitivities of detection of MYC abnormalities by FISH vs. WGS. Given that MYC abnormalities often display remarkable genomic heterogeneity with numerous gene partners, reduced detection of MYC abnormalities by FISH is not unexpected. This hypothesis is supported by lower frequencies of MYC abnormalities found by FISH (15%) vs. NGS (30-35%) consistent with ~50% false-negative rate of the MYC FISH probe (Smadbeck, et al. BCJ, 2019). To better understand the role of MYC in myeloma disease outcome, we compared the MYC abnormality subtype identified by FISH or NGS vs. MYC gene expression levels and overall survival. Methods: We performed a retrospective study of newly diagnosed MM patients seen at Mayo Clinic or enrolled in the MMRF CoMMpass trial. For Mayo cases, MYC FISH results (breakapart probe, Abbott) were obtained from the Mayo Clinic Genomics database (N=1342) and mate pair sequencing (MPseq) was performed on 140 cases. For CoMMpass cases, we obtained tumor long-insert whole genome sequencing (WGS), RNA sequencing (RNAseq) for gene expression and clinical outcome data. Overall survival (OS) was defined as time from diagnosis to death from any cause or to last follow up. Survival curves were estimated using Kaplan Meier and compared using the Log-Rank test. Statistical analyses performed using SPSS and JMP with significance determined when P <0.05. Results: We first evaluated the impact of MYC abnormalities on OS when detected by FISH or NGS. In Mayo cases, OS was significantly shorter in patients with MYC abnormalities compared to patients without MYC abnormalities using FISH (5.3 vs. 8.0 years, P<0.001, N=1342). In contrast, there was no significant difference in OS between patients with or without MYC or abnormalities using MPseq or WGS in both the Mayo and CoMMpass cohorts (Mayo: 6.4 vs. and 6.9 years P=0.78, N=140; CoMMpass: 4.9 vs. and 5.1 years P=0.74, N=546). Since FISH-detected MYC abnormalities were associated with poor outcome, we evaluated differences in the types of MYC abnormalities identified FISH and genome sequencing; 270 of 658 CoMMpass cases had a MYC abnormality and 12 abnormality subgroups were identified. In the Mayo cases, FISH preferentially detected translocations and complex abnormalities and missed insertions with flanking duplicating sequences or terminal tandem duplications (TTD) that occur telomeric to MYC. Since the level of MYC expression should be a consequence of the various genomic abnormalities altering the MYC gene region, we compared MYC expression levels in relation to MYC abnormality subgroups. Highest expression was seen with MYC amplification, followed by Ig abnormalities, non-Ig abnormalities, complex deletion/duplications, proximal deletions, non-Ig insertions, terminal deletions, TTD, trisomy 8, no MYC structural variation, monosomy 8 and cases with MAX mutations had the lowest expression. Abnormalities identified by FISH had higher MYC expression (83.5 TPM) compared to cases predicted to be missed by FISH (63.2 TPM). We tested if high MYC expression, irrespective of MYC structural abnormality, was associated with differences in OS. Boxplot analysis was used to categorize MYC expression in 631 CoMMpass patients as top quartile/high MYC expression (Q4≥ 75 TPM, n=159) and bottom quartile/low MYC expression (Q1≤ 16.5 TPM, n= 158) (see Figure). OS was significantly shorter in patients with high MYC expression compared to patients with low MYC expression (4.6 vs. 5.3 years, P <0.038). Conclusion: We show that FISH detects only a subset of the MYC abnormalities detected by genome sequencing, and that FISH-detected MYC abnormalities are associated with higher MYC gene expression and decreased survival. Figure 1 Disclosures Kumar: Kite Pharma: Consultancy, Research Funding; Janssen Oncology: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; AbbVie: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Oncopeptides: Consultancy, Other: Independent Review Committee; IRC member; Dr. Reddy's Laboratories: Honoraria; Cellectar: Other; Takeda: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Novartis: Research Funding; Tenebio: Other, Research Funding; Carsgen: Other, Research Funding; Amgen: Consultancy, Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments, Research Funding; Merck: Consultancy, Research Funding; Genecentrix: Consultancy; BMS: Consultancy, Research Funding; Karyopharm: Consultancy; Celgene/BMS: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Genentech/Roche: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Sanofi: Research Funding; MedImmune: Research Funding; Adaptive Biotechnologies: Consultancy.

AbstractMetaphase cytogenetic abnormalities, plasma cell proliferation index (PCPro), and gain 1q by fluorescence in situ hybridization (FISH) are associated with inferior survival in newly diagnosed multiple myeloma (MM) treated with novel agents; however, their role in risk stratification is unclear in the era of the revised International Staging System (R-ISS). The objective of this study was to determine if these predictors improve risk stratification in newly diagnosed MM when accounting for R-ISS and age. We studied a retrospective cohort of 483 patients with newly diagnosed MM treated with proteasome inhibitors and/or immunomodulators. On multivariable analysis, R-ISS, age, metaphase cytogenetic abnormalities (both in aggregate and for specific abnormalities), PCPro, and FISH gain 1q were associated with inferior progression-free (PFS) and overall survival (OS). We devised a risk scoring system based on hazard ratios from multivariable analyses and assigned patients to low-, intermediate-, and high-risk groups based on their cumulative scores. The addition of metaphase cytogenetic abnormalities, PCPro, and FISH gain 1q to a risk scoring system accounting for R-ISS and age did not improve risk discrimination of Kaplan-Meier estimates for PFS or OS. Moreover, they did not improve prognostic performance when evaluated by Uno’s censoring-adjusted C-statistic. Lastly, we performed a paired analysis of metaphase cytogenetic and interphase FISH abnormalities, which revealed the former to be insensitive for the detection of prognostic chromosomal abnormalities. Ultimately, metaphase cytogenetics lack sensitivity for important chromosomal aberrations and, along with PCPro and FISH gain 1q, do not improve risk stratification in MM when accounting for R-ISS and age.

Background: Small lymphocytic lymphoma/chronic lymphocytic leukemia (SLL/CLL) is a lymphoproliferative disorder of small mature B-cells, most commonly presenting with peripheral blood and bone marrow involvement. Tumoral lesions are variably encountered, resulting from either lymph node involvement or, less commonly, infiltration into virtually any extramedullary site. The prognostic assessment of patients with SLL/CLL relies strongly on the identification of recurrent chromosomal abnormalities, which are routinely tested by fluorescence in situ hybridization (FISH) on peripheral blood or bone marrow specimens. However, the incidence of such recurrent chromosomal abnormalities on tumoral lesions has only been studied on small series, and its concordance with peripheral blood and/or bone marrow testing remains unknown. We hereby report a large series of chromosomal abnormalities detected on tumoral SLL/CLL lesions, based on a validated FISH panel for formalin-fixed/paraffin-embedded (FFPE) biopsy sections. Methods: FISH was performed at Mayo Clinic on FFPE tissue sections from biopsies obtained from May 2014 to November 2018, as clinically indicated. Pathology reports and H&E-stained sections were reviewed and were consistent with a diagnosis of SLL/CLL in all cases. Probes were validated to detect previously described chromosomal abnormalities in SLL/CLL, including trisomy 12 (+12) and deletions of 6q23 (6q-), 11q22.3 (11q-), 13q14.3 (13q-) and 17p13.1 (17p-). Available FISH results performed on peripheral blood or bone marrow samples from these patients were also reviewed for comparison. Results: Tissue biopsies involved by SLL/CLL from 346 patients were evaluated by FISH. The majority of specimens were either lymph nodes (65%) or soft tissue masses (29%). The median age was 66.9 years (range: 36 to 91), and the male to female ratio was 2.1:1. FISH abnormalities were identified in 60% of evaluated tissue sections. The most frequently detected aberration was +12 (35%), followed by 13q- (24%), 11q- (15%), 17p- (6%) and 6q- (2%) (Figure A). In particular, the incidence of +12 was significantly higher, and the incidence of 13q- significantly lower compared to frequencies previously reported on peripheral blood or bone marrow specimens (p<0.01 for both abnormalities, in comparison to a recently published cohort of 1585 patients: Br J Haematol 2016;173:105). Most cases had 1 abnormality (55%), with fewer patients having 2 abnormalities (13%), and only 1 case showing 3 abnormalities. Of 47 patients with 2 or more chromosomal aberrations, most (72%) had 13q- in combination with either 11q- (7 cases), +12 (10 cases) or 17p- (7 cases) (Figure 1B). Of 29 patients with positive blood or bone marrow FISH results within 12 months of tissue biopsy, 7 patients (24%) had discrepant results, all of which were limited to discordant +12 and/or 13q- detection. In 14 additional patients with positive blood or bone marrow FISH results more than 12 months before or after tissue biopsy, discordant results were found in 3 cases (21%), all of which indicated gains of 17p- (2 cases) or 11q- (1 case) on the follow-up analysis. Conclusions: We hereby report the largest documented series (to the best of our knowledge) of FISH results performed on tumoral lesions of SLL/CLL. Trisomy 12 was overrepresented in tumoral lesions, as compared to the reported predominance of 13q- in leukemic involvement. Discrepant results between concurrent tumoral and leukemic FISH testing were limited to differences in +12 and 13q- in our series. We also document the acquisition of aberrancies of unfavorable prognosis (17p- and 11q-) on follow up FISH analysis in a small subset of patients, which should be taken into account when considering repeat FISH studies. Figure Disclosures Horna: MorphoSys AG: Research Funding.

Purpose: Multiple myeloma (MM) is a plasma cell (PC) malignancy with an increasing incidence in the US. Epidemiological studies demonstrate a 2-3 fold higher incidence of the pre-malignant monoclonal gammopathy of undetermined significance (MGUS) and MM with a ~4-year younger age of onset among African Americans (AA) compared to European Americans (EAs) (Fonseca, Leukemia, 2017). With equal access to care, AAs have better overall survival compared to EAs (Waxman, Blood, 2010). This disparity may be explained by ancestral-associated genetic predisposition of AAs to development of monoclonal gammopathies and to specific acquired, cytogenetically-defined subtypes. Using calculated genetic ancestry data, we have previously identified a higher prevalence of IgH translocations t(11;14), t(14;16) and t(14;20) in individuals with >80% African ancestry (Baughn, BCJ, 2018). Since SNP rs9344 encoding the CCND1 870G>A polymorphism has been reported in association with increased risk of t(11;14) (Weinhold, Nature Genetics, 2013), we investigated whether rs9344 correlates with African ancestry and with t(11;14) in our cohort of patients with plasma cell dyscrasias. Methods: We studied 898 patients with monoclonal gammopathies who had undergone uniform testing to identify MM-specific cytogenetic abnormalities. DNA from bone marrow samples was genotyped on the Precision Medicine Research Array and biogeographical ancestry was assessed using the Geographic Population Structure Origins tool (Elhaik, Nat Commun, 2014). Plasma cell proliferative disorder FISH of immunoglobulin (cIg)-stained positive plasma cells was performed as described (Baughn, BCJ, 2018). Individuals were divided into three ancestral groups: 1. EAs (<0.1% African ancestry and <30% Asian ancestry); 2. AAs (> 80% African ancestry); and 3. Other. Chi-squared test was used to determine the overall comparison between the 3 ancestral groups and also between ancestral groups 1 vs 2, and 2 vs 3 using pairwise comparison. All tests were two-sided with alpha level set at 0.05 for overall statistical significance. Pairwise comparison was considered statistically significant when p<0.025 based on Bonferroni method for multiple comparisons. Results: We identify increased risk of development of either a t(11;14), t(14;16) or t(14;20) in AAs (48.8%) compared to EAs (33.6%) (p-value=0.0051). To explore the genetic basis of increased t(11;14) specifically (37.4% AAs vs. 27.3% p-value=0.049), we evaluated the frequency of the G risk allele of rs9344 in relation to African ancestry. The frequency of the G risk allele was higher in AAs (0.81) compared to EAs (0.59) (p-value <0.0001) and also higher in t(11;14) cases (0.73) compared to non-t(11;14) controls (0.58) (p-value <0.0001). A multivariate model identified only rs9344 as significantly associated with t(11;14) after adjusting for age, gender and race group suggesting that it plays a role in the development of t(11;14) (p-value <0.001 for GG, p-value=0.005 for AG). To test if these results are replicable, we studied the MMRF CoMMpass cohort. This cohort includes individuals with newly diagnosed MM along with self-report race information and translocation data from long insert whole genome sequencing. Although t(11;14) was not enriched in self-reported Black individuals from this cohort (17.5% Black vs. 20.4% White, p-value=0.47), there was association between the rs9344 and self-reported Black race (p-value <0.0001) and with the presence of t(11;14) when the t(11;14) was analyzed by long insert whole genome sequencing (p-value=0.0001). Conclusions: To our knowledge, this study includes the largest group of African individuals with an abnormal plasma cell clone along with uniformly collected FISH, genotyping and ancestry data. We have identified in this diverse population the association of the CCND1 870G>A polymorphism (rs9344) with African ancestry and with t(11;14) suggesting that it plays a role in the development of t(11;14) plasma cell dyscrasias. Disclosures Elhaik: DNA Diagnostics Center: Consultancy. Baird:DNA Diagnostics Center: Employment. Cerhan:Janssen: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; NanoString: Research Funding. Bergsagel:Celgene: Consultancy; Ionis Pharmaceuticals: Consultancy; Janssen Pharmaceuticals: Consultancy. Dispenzieri:Alnylam: Research Funding; Akcea: Consultancy; Intellia: Consultancy; Janssen: Consultancy; Pfizer: Research Funding; Takeda: Research Funding; Celgene: Research Funding. Kumar:Janssen: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Takeda: Research Funding.

Purpose: B-cell acute lymphoblastic leukemia/lymphoma (B-ALL/LBL) represents the most common childhood malignancy. Classification of recurrent genetic abnormalities in B-ALL/LBL is essential for risk stratification and patient management. Observed in approximately 5% of B-ALL/LBL cases, hypodiploidy is considered a poor prognostic finding and can be further characterized as near-haploidy (24-31 chromosomes), low hypodiploidy (32-39 chromosomes) and high hypodiploidy (40-43 chromosomes). Importantly, masked hypodiploid clones that have undergone endoreduplication can be mischaracterized as hyperdiploidy, a favorable prognostic finding in B-ALL/LBL. These "doubled" hypodiploid clones are termed pseudo-hyperdiploid and their accurate detection is critical. Mate-pair sequencing (MPseq) is a next-generation sequencing (NGS) technology designed to sequence larger DNA fragments (2000-5000bp) than paired-end sequencing. This allows for the detection of large genetic rearrangements (e.g. translocations, inversions, etc.) and copy number variants (CNVs) at a high resolution with low base coverage. It has demonstrated particular clinical utility for genetic characterization of hematologic malignancies. To expand the role of MPseq in the evaluation of hematologic neoplasms, we aimed to improve the analysis of MPseq results to allow for the detection of copy-neutral loss of heterozygosity (cnLOH) that would enable the differentiation between hyperdiploid and pseudo-hyperdiploid clones. Methods: A new algorithm was applied that statistically analyzes common SNP locations in MPseq data in order to detect both cnLOH regions, and provides global heterozygosity levels at a resolution that allows for the detection of hypodiploidy. This method accounts for the low base-coverage of MPseq data (<10x) in order to provide the highest possible accuracy and precision without increasing cost by requiring changes to the input or sequencing requirements. The algorithm was applied to 17 B-ALL samples classified by conventional chromosome analysis, FISH, and/or chromosomal microarray as either pseudo-hyperdiploidy (n=8) or hyperdiploidy (n=9). The cases were sequenced using MPseq with 101bp read lengths across a range of base coverages (1-10x; 30-135 million fragments) and tumor percentages (50-100%). Results: We demonstrate the method's ability to differentiate between hyperdiploidy and pseudo-hyperdiploidy in all cases without any changes to the MPseq input or sequencing requirements. We detected an average of 11.5 whole-chromosome cnLOH (range 8-20) in the pseudo-hyperdiploidy cases, compared to an average of 0.67 whole-chromosome cnLOH (range 0-2) in the hyperdiploidy cases. Additionally, the method allows for the detection of cnLOH regions across the genome. For example, we observed a recurrent cnLOH of chromosome 9 in the hyperdiploid subtype (3/9 hyperdiploid cases), which is a recurrent abnormality in the disease. The method provides an easy to read visual output that compares favorably to the output of chromosomal microarray, increasing its utility for clinical application. Conclusions: This advancement in the analysis of low-coverage sequencing data makes MPseq available for the genetic characterization of B-ALL/LBL, where hypodiploidy is a primary cytogenetic abnormality and is sometimes missed by conventional cytogenetic techniques. Additionally, the algorithm allows for the detection of cnLOH regions across the genome, which is important across many disease types for diagnosis, prognosis, and the detection of potential therapeutic targets. The addition of the algorithm to the MPseq analysis pipeline makes it a more complete genetic characterization tool and brings it closer to its promise as a potential single assay replacement for conventional cytogenetic techniques. Disclosures No relevant conflicts of interest to declare.

Abstract Background: We previously demonstrated that putative clinical epidemiologic exposures associated with leukemia risk are prevalent among AML patients, and some are associated with unique cytogenetic risk group and with clinical phenotype (Finn, Cancer Epidemiol, 2015). Herein, we studied genome-wide DNA methylation in a cohort of AML patients to evaluate the association of individual hyper- and hypo-methylated CpG sites with epidemiologic exposures and overall survival. Methods: The Mayo Clinic AML Epidemiology Cohort is a highly annotated retrospective case series of 295 consecutive patients (pts) with AML diagnosed and treated at Mayo Clinic Florida and Arizona, with central cytogenetics performed in all cases. The prevalence of clinical epidemiologic exposures, past medical and family history as well as medication use and lifestyle was systematically obtained. After IRB approval, we interrogated the cytogenetic database and successfully obtained leukemia DNA from available remnant diagnostic cytogenetic cell pellets in a cohort of 148 AML patients in the Mayo epidemiology case series and performed an assessment of genome-wide DNA methylation using the Infinium HumanMethylation450K BeadChip. Samples were processed using the R Bioconductor package 'minfi' using Subset Within Array Quantile Normalization (PMID: 22703947). Individual CpGs that did not reach a detection p-value of <0.05 were filtered out. An internal control was included on each array to control for significant batch effects. To determine differential methylation status of 473,864 individual CpG sites (after exclusion of 11,648 that did not pass detection p-value QC), CpG sites with low interpatient variability, a standard deviation <0.05 of methylation values, and an interquartile range <0.05 of methylation values and X/Y chromosome probes were excluded from analysis. Epidemiologic and important clinical variables occurring in at least 10 pts or previously-identified as of unique interest but in fewer than 10 pts were evaluated, including sex, BMI, performance status and comorbidities, tobacco and alcohol use, family history of hematologic malignancy, medications of interest, history of toxin exposure, and history of immunosuppression and/or solid organ transplant or of secondary and therapy-related AML (t-AML). Associations of differential hypo or hypermethylation at 281,259 CpG sites with epidemiologic exposures/clinical variables were evaluated using Spearman's test of correlation (continuous or ordinal exposures), a Wilcoxon rank sum test (dichotomous exposures), or a Kruskal-Wallis rank sum test (multi-category exposures). A Bonferroni correction was applied for multiple testing, after which p <1.8 x 10-7 was considered as significant. To reduce the likelihood of false-negative findings, we additionally considered p <5 x 10-6 as indicating suggestive evidence of an association. CpG sites and associated gene and function was determined using Illumina manifest file & www.ncbi.nlm.nih.gov/gene. Results: Statistically significant associations (p <1.8 x 10-7) with individual epidemiologic and clinical exposures were identified for 109 unique CpG sites, corresponding to differential methylation in the genes listed in Table. Specifically, obesity (predominantly hypomethylation), specific cytogenetic lesions and risk group, and gender were highly significantly associated with unique CpG methylation status, but not smoking, toxin exposure, family history, comorbidity or performance status, secondary or t-AML, immunosuppression, medication use, of family history in the analysis. A further 353 unique CpG sites had defined suggestive associations (ongoing analysis). We also identified 8 additional CpG sites where differential methylation was associated with overall survival (p <5 x 10-6, Table). Conclusion: Obesity, cytogenetic lesions, and sex are associated with differential methylation of unique CpG sites at AML diagnosis, using stringent univariate statistical criteria. Significant CpG sites were identified in genes previously linked to AML biology and prognosis (DOCK6, HOXB3, MIR10A, FOXN3/CHES1, GPX1, MYST2/KAT7, PTPRD), but some represent novel findings in AML. These preliminary results suggest an association of some AML risk factors and clinical variables with unique gene methylation and will undergo validation in a prospective AML epidemiology dataset. Disclosures Cerhan: Jannsen: Other: Scientific Advisory Board; Nanostring: Research Funding; Celgene: Research Funding. Foran:Agios: Research Funding; Xencor, Inc.: Research Funding.

Abstract Monoclonal gammopathies, including multiple myeloma (MM), represent a group of plasma cell (PC) disorders that comprise of mostly incurable hematopoietic malignancies with an increasing incidence in the US. Previous epidemiological studies demonstrated a 2-3 fold higher incidence of monoclonal gammopathy of undetermined significance (MGUS) and a similarly higher incidence of MM along with a ~4-year younger age of onset among African Americans (AA) compared to European Americans (EAs) (Fonseca, Leukemia, 2017). This suggests a possible ancestral-associated genetic predisposition of AAs to the development of monoclonal gammopathies (Landgren, Blood, 2006). When access to care is equal, AAs have a better overall survival compared to EAs suggesting that AAs may have a genetic predisposition that renders them better responders to treatment or have more favorable cytogenetic subtypes of MM (Waxman, Blood, 2010). Previous efforts to understand this disparity have relied on self-reported race rather than genetic ancestry. We hypothesize that quantifying genetic ancestry is necessary to fully understand the genetic mechanisms of racial disparities of monoclonal gammopathies. We describe our study of 881 patients with monoclonal gammopathies who had undergone uniform testing to identify MM-specific cytogenetic abnormalities. DNA from the bone marrow samples was genotyped on the Precision Medicine Research Array. Biogeographical ancestry was assessed using the Geographic Population Structure Origins tool, which provides the ancestral breakdown of 36 admixture components for each individual representing different geographic regions and outputs admixture proportions corresponding to those ancestries (Elhaik, Nat Commun, 2014). We evaluated whether an increase in the percentage of African Ancestry altered the odds of any primary cytogenetic abnormality. We demonstrated that a 10% increase in the percentage of African ancestry was associated with a 6% increase in the odds of detecting either an t(11;14), t(14;16) or t(14;20) (odds ratio = 1.06, 95% CI: 1.02 - 1.11; p-value = 0.05). Although we observed an increase in the odds of each of the individual translocations with 10% increase in African ancestry, l t(11;14) (OR=1.03) t(14;16) (OR=1.11) and t(14;20) (OR=1.10), these three abnormalities were combined to achieve greater statistical power. The differences in cytogenetic abnormalities were most striking among individuals with ≥80.0% African (n=120) compared to individuals with <0.1% African ancestry (n=235). Using these cutoff values comparing the ≥80.0% and <0.1% African ancestry cohorts, there was a higher prevalence of t(11;14), t(14;16) and t(14;20) (51% vs. 33%, respectively, p-value=0.008) and a lower prevalence of trisomies (with or without IgH translocations) (48.3% vs. 61.3%, respectively, p-value=0.066). In addition, the ≥80% African ancestry cohort also displayed a slightly lower prevalence of monosomy 13/13q deletion compared to the cohort with <0.1% African ancestry (34.2% vs. 38.7%, respectively, p-value=0.021). Further, we observed a significantly higher prevalence in the proportion of females with monoclonal gammopathies among the ≥80% African ancestry cohort compared to the cohort with <0.1% African ancestry (56.7% vs. 42.1%, respectively, p-value=0.028). We complement our past studies that relied on self-reported race and characterized patients' demographic and uniformly collected cytogenetic data in relation to genetically defined African ancestry. We demonstrate the prevalence of having one of three specific subtypes (i.e., t(11;14), t(14;16), or t(14;20)) was significantly higher in those with highest (≥80%) compared to lowest (<0.1%) African ancestry demonstrating African ancestry is associated with a subtype distribution of MM that differs from non-African individuals. These differences were only revealed after analysis of individuals with the highest and lowest percentage of African ancestry. Since 38.3% of the individuals with ≥80% African ancestry have the favorable t(11;14) translocation (in comparison to 26.8% of <0.1% African individuals), this finding may explain improved survival with equal access to care. Understanding the genetic mechanisms of this disparity is a fundamental step to understanding differences in incidence and outcomes of patients with monoclonal gammopathies. Disclosures Elhaik: DNA Diagnostics Center: Consultancy. Baird:DNA Diagnostics Center: Employment. Cerhan:Jannsen: Other: Scientific Advisory Board; Nanostring: Research Funding; Celgene: Research Funding. Stewart:Amgen Inc., BMS, Celgene, Takeda, Roche, Seattle Genetics, Janssen, Ono: Consultancy; Amgen Inc., Celgene, Roche, Seattle Genetics: Research Funding. Dispenzieri:Celgene, Takeda, Prothena, Jannsen, Pfizer, Alnylam, GSK: Research Funding. Kumar:Novartis: Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Research Funding.

Abstract Background: The current standard of care for eligible newly diagnosed multiple myeloma (MM) patients is induction therapy with novel agents followed by high dose chemotherapy and autologous stem cell transplant (ASCT). The International Myeloma Working Group proposed the Revised International Staging System (R-ISS) based on the presence of adverse chromosomal abnormalities (CA) detected by FISH (t(4;14), t(14;16) or del17p), in combination with ISS and LDH at diagnosis. However, there are a limited number of studies that have validated this risk model in the transplant and novel agents setting. Aims: To determine whether R-ISS is an appropriate risk-model for estimating overall survival (OS) and progression free survival (PFS) for transplant-eligible MM patients. Patients and Methods: We retrospectively studied a cohort of 519 MM patients who received novel drugs in the induction and subsequently underwent ASCT at Mayo Clinic Arizona from 2005 to 2014. In all, 95 patients met the inclusion criteria: comprising complete data at diagnosis (ISS, serum LDH level, and CA by FISH). The primary endpoint was OS from SCT and the secondary end point was PFS from ASCT. R-ISS groups were defined as described by Palumbo et al. J Clin Oncol. 2015; 33(26):2863-2869. Results: There were 50 (52.6%) men and 45 (47.4%) women who underwent ASCT in this period, with a median age at the time of transplant of 66-years-old (range, 36-78). There were 27 patients (28.4%) with high-risk CA: 12 patients (12.6%) with del17p; 11 patients (11.6%) with t(4;14); and 6 (6%) with t(14;16). In addition, 8 patients (8.5%) had high LDH levels and 9 patients (9.5%) presented with renal impairment at diagnosis. The patients were staged at diagnosis according to the three R-ISS groups: 44 patients (46.3%) had stage I, 26 (27.4%) had stage II, and 25 (26.3%) had stage III. CyBorD was the preferred induction regimen which was received by 42 patients (44%). There were 14 patients (15%) who received at least 2 lines of induction. All patients were in at least partial response (PR) at the moment of transplant: 32 in complete response (CR), 32 in very good partial response (VGPR) and the remaining 31 in PR. The response achieved at day +100 after ASCT improved, with 54 patients (57%) in CR, and only 18 patients (19%) in PR. After a median follow-up of 61 months (range, 14-135), median OS from SCT was 108 months (95% CI: 85 - 132 months) and the median PFS was 45.4 months (95% CI: 31.1 - 53.8 months) in the whole series.MM patients with R-ISS III had a significantly shorter median OS compared to patients with R-ISS II or R-ISS I (32.1 months vs. 94.7 months vs. not reached, respectively, P<0.0001) (Figure). No statistically significant differences in baseline characteristics were identified among these groups to explain the differences in OS observed. PFS among these groups was not statistically significant, only showing a trend towards shorter PFS in R-ISS III compared with either R-ISS I or II: median 22.1 months vs. 35.7 months, respectively, (P=0.2). Renal impairment at diagnosis, IgA subtype, ≥ 2 lines of induction treatment, and less than CR achieved at day +100 after ASCT were also associated with significantly inferior OS. Multivariate analysis selected R-ISS as an independent predictor for OS (HR: 2.3, 95% CI: 1.1-4.8; P=0.03), as well as ≥ 2 lines before ASCT. CR at day +100 after ASCT was the most important independent factor for predicting PFS (HR: 0.4; 95% CI: 0.2-0.6; P<0.001). Conclusion: R-ISS assessed at diagnosis was an independent predictor for OS after ASCT in our series, with median OS for the different R-ISS groups comparable to those reported by Palumbo et al. in their subgroup of younger patients. Thus, this study lends further support for the R-ISS as a reliable prognostic tool for estimating OS in transplant-eligible MM patients. In addition, new treatment approaches are needed for the high-risk patients (R-ISS III) with a median OS of 2.5 years. Figure Figure. Disclosures Reeder: Millennium: Research Funding; BMS: Research Funding; Celgene: Research Funding; Novartis: Research Funding. Mikhael:Abbvie: Research Funding; Onyx: Research Funding; Sanofi: Research Funding; Celgene: Research Funding. Bergsagel:Amgen, BMS, Novartis, Incyte: Consultancy; Novartis: Research Funding. Stewart:celgene: Consultancy. Fonseca:Janssen: Consultancy; Celgene: Consultancy; Sanofi: Consultancy; Novartis: Consultancy; Bayer: Consultancy; AMGEN: Consultancy; AMGEN: Consultancy; AMGEN: Consultancy; Patent: Patents & Royalties: Prognostication of MM based on genetic categorization of FISH of the disease; AMGEN: Consultancy; Millennium, a Takeda Company: Consultancy; Janssen: Consultancy; Sanofi: Consultancy; Patent Pending: Patents & Royalties: The use of calcium isotopes as biomarkers for bone metabolisms; Novartis: Consultancy; Patent: Patents & Royalties: Prognostication of MM based on genetic categorization of FISH of the disease; Millennium, a Takeda Company: Consultancy; Millennium, a Takeda Company: Consultancy; Bayer: Consultancy; Celgene: Consultancy; Patent Pending: Patents & Royalties: The use of calcium isotopes as biomarkers for bone metabolisms; Patent: Patents & Royalties: Prognostication of MM based on genetic categorization of FISH of the disease; Patent Pending: Patents & Royalties: The use of calcium isotopes as biomarkers for bone metabolisms; BMS: Consultancy; Millennium, a Takeda Company: Consultancy; BMS: Consultancy; Patent: Patents & Royalties: Prognostication of MM based on genetic categorization of FISH of the disease; Patent Pending: Patents & Royalties: The use of calcium isotopes as biomarkers for bone metabolisms.

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.