Identification of multiple risk loci and regulatory mechanisms influencing susceptibility to multiple myeloma

Genome-wide association studies (GWAS) have transformed our understanding of susceptibility to multiple myeloma (MM), but much of the heritability remains unexplained. We report a new GWAS, a meta-analysis with previous GWAS and a replication series, totalling 9974 MM cases and 247,556 controls of European ancestry. Collectively, these data provide evidence for six new MM risk loci, bringing the total number to 23. Integration of information from gene expression, epigenetic profiling and in situ Hi-C data for the 23 risk loci implicate disruption of developmental transcriptional regulators as a basis of MM susceptibility, compatible with altered B-cell differentiation as a key mechanism. Dysregulation of autophagy/apoptosis and cell cycle signalling feature as recurrently perturbed pathways. Our findings provide further insight into the biological basis of MM.

Serum free light chain levels and renal function at diagnosis in patients with multiple myeloma

Background

Renal impairment (RI) is common in multiple myeloma (MM) and is associated with poor survival. This study reports the associations between renal function and disease characteristics including serum free light chain (FLC) level at diagnosis in patients with MM.

Methods

Using data from the Medical Research Council Myeloma IX trial, a multicentre, randomized, open-label, phase III and factorial-design trial, we assessed the relationships between renal function, demographic, and disease characteristics, including serum FLC levels, in 1595 newly diagnosed MM patients. Multivariable linear regression was utilised to identify factors that were associated with renal function at diagnosis. A receiver operating characteristic curve (ROC) was used to identify the optimal threshold for serum FLC level at diagnosis to predict severe RI.

Results

52.8% of patients had an estimated glomerular filtration rate (eGFR) ≥60 ml/min/1.73 m² (no RI), 37.3% an eGFR 30–59 ml/min/1.73 m² (mild to moderate RI), and 9.8% an eGFR < 30 ml/min/1.73 m² (severe RI). In a multivariable analysis, factors independently and negatively associated with eGFR at diagnosis were: higher serum FLC level, female gender, and older age. Elevated serum FLC level at diagnosis, irrespective of the paraprotein type, was strongly associated with severe RI. Receiver operating characteristic curve analysis showed a serum FLC level of > 800 mg/L as the optimal cut-off associated with severe RI (area under curve 0.86, 95% confidence interval 0.77–0.84).

Conclusion

There was a strong relationship between higher serum FLC levels at diagnosis and the severity of RI that was irrespective of the paraprotein type. We report an increased risk of severe RI in patients presenting with serum FLC levels above 800 mg/L at diagnosis.

Quality of life during and following sequential treatment of previously untreated patients with multiple myeloma: findings of the Medical Research Council Myeloma IX randomised study

In the Medical Research Council (MRC) Myeloma IX trial (ISRCTN684564111) patients were randomised to sodium clodronate or zoledronic acid and induction treatment: cyclophosphamide, vincristine, doxorubicin and dexamethasone (CVAD) or cyclophosphamide, thalidomide and dexamethasone (CTD) followed by autologous stem cell transplant (ASCT) in the intensive pathway; attenuated CTD or melphalan and prednisolone (MP) in the non-intensive pathway. Subsequent randomisation allocated patients to either thalidomide or observation. The European Organisation for Research and Treatment of Cancer (EORTC) quality of life (QoL) questionnaires, QLQ-C30 and QLQ-MY24, were administered at baseline, 3, 6 and 12 months and annually thereafter, enabling the effect of sequential treatment on patient-reported health-related QoL (HR-QoL) to be investigated. The protocol specified four subscales of interest: Pain, Fatigue, Global Health Status/Quality of Life and Physical Functioning at 3, 6 and 12 months that were compared using linear models. The intensive pathway showed significant differences in favour of CTD for Fatigue at 3 months and Physical Functioning at 12 months. The non-intensive pathway and maintenance phase reported significant differences at 3 months; Pain (improved with attenuated CTD) and Global Health status/Quality of Life (improved with observation). The improved outcomes in MRC Myeloma IX were accompanied by some beneficial and few detrimental effects on HR-QoL.

MAFb protein confers intrinsic resistance to proteasome inhibitors in multiple myeloma

Background

Multiple myeloma (MM) patients with t(14;20) have a poor prognosis and their outcome has not improved following the introduction of bortezomib (Bzb). The mechanism underlying the resistance to proteasome inhibitors (PIs) for this subset of patients is unknown.

Methods

IC50 of Bzb and carfilzomib (CFZ) in human myeloma cell lines (HMCLs) were established by MTT assay. Gene Expression profile (GEP) analysis was used to determine gene expression in primary myeloma cells. Immunoblotting analysis was performed for MAFb and caspase family proteins. Immunofluorescence staining was used to detect the location of MAFb protein in MM cells. Lentiviral infections were used to knock-down MAFb expression in two lines. Apoptosis detection by flow cytometry and western blot analysis was performed to determine the molecular mechanism MAFb confers resistance to proteasome inhibitors.

Results

We found high levels of MAFb protein in cell lines with t(14;20), in one line with t(6;20), in one with Igλ insertion into MAFb locus, and in primary plasma cells from MM patients with t(14;20). High MAFb protein levels correlated with higher IC50s of PIs in MM cells. Inhibition of GSK3β activity or treatment with Bzb or CFZ prevented MAFb protein degradation without affecting the corresponding mRNA level indicating a role for GSK3 and proteasome inhibitors in regulation of MAFb stability. Silencing MAFb restored sensitivity to Bzb and CFZ, and enhanced PIs-induced apoptosis and activation of caspase-3, − 8, − 9, PARP and lamin A/C suggesting that high expression of MAFb protein leads to insensitivity to proteasome inhibitors.

Conclusion

These results highlight the role of post-translational modification of MAFb in maintaining its protein level, and identify a mechanism by which proteasome inhibitors induced stabilization of MAFb confers resistance to proteasome inhibitors, and provide a rationale for the development of targeted therapeutic strategies for this subset of patients.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4602-4) contains supplementary material, which is available to authorized users.

Abstract 5324: Intragenic DNA-hypomethylation promotes overexpression of ITGB7 in MF subgroup of multiple myeloma

Integrin-β7 is part of an extensive family of glycoproteins and is overexpressed in the MF subgroups in Multiple Myeloma (MM), contributing to drug resistance and poor survival. ITGB7 promotes adhesion and proliferation of myeloma cells in bone-marrow stroma by supplementing growth factors like VEGF. Here, we investigate the possible epigenetic mechanism of ITGB7 overexpression in the MF subgroup, comprising of t(14;16) and t(14;20) myeloma. Newly diagnosed MM (NDMM) patient bone marrow aspirates underwent CD138 cell selection to enrich tumor cells to &gt;98%. Samples consisted of those with a t(14;16) (n=17), t(14;20) (n=7), t(4;14) (n=9), t(11;14) (n=10) and hyperdiploidy (n=19, separated into D1 (n=12) or D2 (n=7 subgroups). NDMM patient samples were compared to plasma cells isolated from age-matched healthy donors (n=4), to determine differential changes in epitranscripts. We performed unbiased genome-wide reduced representation bisulfite sequencing (RRBS) to identify differentially methylated regions (DMRs) in CpG islands, which were validated by Infinium MethylationEPIC arrays (Illumina) in conjunction with gene expression array data (U133 Plus 2.0, Affymetrix) to determine the epitranscriptomic profile in all samples. RRBS was performed using 75 bp reads to a minimum of 20 M reads per sample. Data from MM cells at the Blueprint consortium were also used for annotation of epigenetic marks. Using the RRBS data we identified 26 hypomethylated, overexpressed genes in the MF group samples, which were not present in the other subgroups. In comparison, only 1 gene, FUT7, was hypermethylated and down-regulated in the MF cluster. Most interestingly, we identified ITGB7 amongst the hypomethylated, overexpressed genes. With an in-depth analysis we identified 4 significant (p&lt;0.05) DMRs across intragenic regions of ITGB7, within a 2.5 kb region. Mean methylation across the DMRs reduced from 58% to 22% (p&lt;0.01) in t(14;16) and 39% (p=0.02) in t(14;20) with concomitant overexpression of ITGB7 in the t(14;16), 19.5-fold increase, and the t(14;20), 23.4-fold increase, subgroups. These 4 DMRs belong to CpG islands, annotated to be the part of possible intragenic enhancer site with promoter like activity, and enriched for open chromatin structures. The DMRs also align with the hotspot of H3K4me1 marks and a putative binding site of activating transcription factors such as AP1/2 or Sp1. This suggests that the identified DMRs could be within the enhancer that regulates ITGB7 overexpression through DNA-hypomethylation. ITGB7 is a known oncogenic factor in high-risk MM, contributing to cell adhesion, migration and homing. Here we show using combined DNA methylation and expression data that ITGB7 is regulated through hypomethylation of the an enhancer region in the MF subgroup in MM.

Citation Format: Samrat Roy Choudhury, Cody Ashby, Ruslana Tytarenko, Yan Wang, Purvi H. Patel, Aneta Mikulasova, Michael Bauer, Shayu Deshpande, Faith E. Davies, Gareth J. Morgan, Brian A. Walker. Intragenic DNA-hypomethylation promotes overexpression of ITGB7 in MF subgroup of multiple myeloma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5324.

Abstract 223: A meta-analysis of genome-wide association studies of multiple myeloma among African Americans

Multiple myeloma (MM) is twice as common in African Americans (AA) compared to European Americans (EA). The reported familial clustering and the elevated MM risk among first-degree relatives of cases implicate genetic susceptibility. Previous genome-wide association studies (GWAS) in EA have identified 16 novel risk loci. In this study, we tested the generalizability of the established risk alleles to AA and conducted a meta-GWAS analysis using two sets of AA to identify additional novel common MM risk variants. In the first study, we genotyped 1,305 incident AA MM cases from the African American Multiple Myeloma Study (AAMMS) using the Illumina HumanCore GWAS array and compared them to 7,078 AA controls from the African Ancestry Prostate Cancer Consortium (AAPC) and African Ancestry Breast Cancer Consortium (AABC) using the Illumina 1M-Duo. In the second study, 95 additional AAMMS cases and 435 AA MM cases from the University of Arkansas for Medical Sciences (UAMS) were genotyped using the Illumina MegaBead Chip and compared to 2,390 AA controls from the Multiethnic Cohort. The Haplotype Reference Consortium (HRC) was used to impute the overlapping typed SNPS from each GWAS case and control set together. Per-allele risk associations were tested for 8,715,278 overlapping genotyped and imputed variants with &gt;1% frequency and &gt;0.8 imputation score using unconditional logistic regression in both sets, and the combined effects were estimated using a fixed-effect meta-analysis. Of the 16 reported risk loci discovered in EA, directional consistency was present for 15 variants; eight of these replicated at nominal significance p&lt;0.05, with the most statistically significant variant being rs4487645 at 7p15.3 (OR=1.38, p=3.56×10-6). AA individuals with polygenic risk scores from these 16 variants (PRS) in the top 10% stratum had a 1.44-fold increased MM risk compared to those with a PRS in the 25th -75th percentiles. Additionally, we identified three suggestive novel loci located at 12q12, 9p24.3 and 9p13.1 at p&lt;1×10-6, with ORs ranging from 1.25-1.55, but none reached genome-wide significance. The variant at 9p24.3 is located in an intron in the KANK1 gene and a correlated SNP in EAs (r2=0.5) is strongly associated with gene expression in neoplastic plasma cells (unpublished, Weinhold and Morgan). Our study replicated most of the reported risk loci discovered among EA, demonstrated that a PRS constructed using the 16 reported risk alleles was associated with MM risk, and provides suggestive evidence for additional loci associated with MM risk in AAs.

Citation Format: Zhaohui Du, Chi Song, Kristin Rand, Niels Weinhold, David Van Den Berg, Amie Hwang, Xin Sheng, Victor Hom, Sikander Ailawadhi, Ajay K. Nooka, Seema Singhal, Karen Pawlish, Edward S. Peters, Cathryn Bock, Ann Mohrbacher, Alexander Stram, Sonja I. Berndt, William Blot, John David Carpten, Antoinette Stroup, Andrew Olshan, Wei Zhang, African Ancestry Breast & Prostate Consortium, Stephen Chanock, Jayesh Mehta, Graham A. Colditz, Jeffrey Wolf, Thomas G. Martin, Michael Tomasson, Mark A. Fiala, Howard Terebelo, Nalini Janakiraman, Laurence Kolonel, Loic LeMarchand, Elad Ziv, Daniel Stram, Ravi Vij, Leon Bernal-Mizrachi, Gareth J. Morgan, Jeffrey A. Zonder, Carol Ann Huff, Sagar Lonial, Robert Z. Orlowski, David V. Conti, Christopher A. Haiman, Wendy Cozen. A meta-analysis of genome-wide association studies of multiple myeloma among African Americans [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 223.

Maintaining therapeutic progress in multiple myeloma by integrating genetic and biological advances into the clinic

INTRODUCTION

Utilizing advances in genetic and immunologic analysis to segment and direct treatment is potentially a way of maintaining therapeutic progress toward cure in multiple myeloma (MM). This approach works well using clinical segments but can be optimized using recent genetic and immunologic technologies, which have opened the possibility of enhancing risk stratification and disease subclassification. Areas covered: This position paper discusses strategies to segment myeloma into subgroups with distinct risk profiles and distinct targetable lesions are presented. Expert commentary: Risk stratified treatment of MM is already a clinical reality that can be enhanced by the developmental of unified segmentation and testing approaches. Mutation-targeted treatment has proven to be effective against the RAS pathway, but is compromised by intra-clonal and spatiotemporal heterogeneity. Identifying new disease segments based on tumor biology or immunological content of the microenvironment offers an exciting new way to control and even eradicate myeloma clones. Going forward, risk and biologically stratified therapy for myeloma is a promising way of maintaining therapeutic progress, as is precision immunotherapy directed by the cellular context of the bone marrow.

Evaluation of a modified Cheatham-Platinum stent for the treatment of aortic coarctation by finite element modelling

Objectives

Stent implantation for the treatment of aortic coarctation has become a standard approach for the management of older children and adults. Criteria for optimal stent design and construction remain undefined. This study used computational modelling to compare the performance of two generations of the Cheatham-Platinum stent (NuMED, Hopkinton, NY, USA) deployed in aortic coarctation using finite element analysis.

Design

Three-dimensional models of both stents, reverse engineered from microCT scans, were implanted in the aortic model of one representative patient. They were virtually expanded in the vessel with a 16 mm balloon and a pressure of 2 atm.

Results

The conventional stent foreshortened to 96.5% of its initial length, whereas the new stent to 99.2% of its initial length. Diameters in 15 slices across the conventional stent were 11.6–15 mm (median 14.2 mm) and slightly higher across the new stent: 10.7–15.3 mm (median 14.5 mm) (p= 0.021). Apposition to the vessel wall was similar: conventional stent 31.1% and new stent 28.6% of total stent area.

Conclusions

The new design Cheatham-Platinum stent showed similar deployment results compared to the conventional design. The new stent design showed slightly higher expansion, using the same delivery balloon. Patient-specific computational models can be used for virtual implantation of new aortic stents and promise to inform subsequent in vivo trials.

HSF1 Is Essential for Myeloma Cell Survival and A Promising Therapeutic Target

Purpose: Myeloma is a plasma cell malignancy characterized by the overproduction of immunoglobulin, and is therefore susceptible to therapies targeting protein homeostasis. We hypothesized that heat shock factor 1 (HSF1) was an attractive therapeutic target for myeloma due to its direct regulation of transcriptional programs implicated in both protein homeostasis and the oncogenic phenotype. Here, we interrogate HSF1 as a therapeutic target in myeloma using bioinformatic, genetic, and pharmacologic means.Experimental Design: To assess the clinical relevance of HSF1, we analyzed publicly available patient myeloma gene expression datasets. Validation of this novel target was conducted in in vitro experiments using shRNA or inhibitors of the HSF1 pathway in human myeloma cell lines and primary cells as well as in in vivo human myeloma xenograft models.Results: Expression of HSF1 and its target genes were associated with poorer myeloma patient survival. ShRNA-mediated knockdown or pharmacologic inhibition of the HSF1 pathway with a novel chemical probe, CCT251236, or with KRIBB11, led to caspase-mediated cell death that was associated with an increase in EIF2α phosphorylation, CHOP expression and a decrease in overall protein synthesis. Importantly, both CCT251236 and KRIBB11 induced cytotoxicity in human myeloma cell lines and patient-derived primary myeloma cells with a therapeutic window over normal cells. Pharmacologic inhibition induced tumor growth inhibition and was well-tolerated in a human myeloma xenograft murine model with evidence of pharmacodynamic biomarker modulation.Conclusions: Taken together, our studies demonstrate the dependence of myeloma cells on HSF1 for survival and support the clinical evaluation of pharmacologic inhibitors of the HSF1 pathway in myeloma. Clin Cancer Res; 24(10); 2395-407. ©2018 AACRSee related commentary by Parekh, p. 2237.

Thymic PTH Increases After Thyroparathyroidectomy in C57BL/KaLwRij Mice

We previously reported a substantial correlation between serum parathyroid hormone (PTH) levels and the myeloma response to proteasome inhibition that suggests a crucial role for the PTH receptor 1 system in the control of myeloma tumor growth. While investigating the role of PTH in the antimyeloma effect, we observed the recovery of serum PTH levels after thyroparathyroidectomy (TPTX). Although the presence of thymus-derived PTH has been reported previously, the existence or role of thymic PTH in the serum remains controversial. Here, TPTX was performed in 8- to 12-week-old C57BL/KaLwRij mice to delineate the potential source(s) for the recovery of serum PTH. Immediately after TPTX, the expected loss of measurable serum PTH was observed. Serum PTH levels recovered 3 to 4 weeks after TPTX. Thirteen endocrine organs from mice with recovered serum PTH were examined. The thymus from control mice expressed measurable and detectable Pth transcripts; however, the Pth transcript level was substantially elevated in tissue from TPTX mice. Western blot analysis of the thymus demonstrated a reproducible and distinct PTH band in thymus tissue that was significantly increased after TPTX. To directly confirm the identity of the distinct PTH band, immunoprecipitated proteins were isolated and subjected to tandem mass spectrometry. After fragmentation and direct peptide sequencing, PTH peptides PTH(1-13) and PTH(54-70), diagnostic for PTH, were identified. These data demonstrate that the murine thymus produces PTH and that after TPTX the thymus becomes the major source of serum PTH, compensating for the loss of the parathyroid glands and returning circulating PTH levels to normal.

Treatment to suppression of focal lesions on positron emission tomography-computed tomography is a therapeutic goal in newly diagnosed multiple myeloma

Fluorine-18 fluorodeoxyglucose positron emission tomography with computed tomography attenuation correction (PET-CT) in myeloma can detect and enumerate focal lesions by the quantitative characterization of metabolic activity. The aim of this study was to determine the prognostic significance of the suppression of PET-CT activity at a number of time points post therapy initiation: day 7, post induction, post transplant, and at maintenance therapy. As part of the TT4-6 trial series, 596 patients underwent baseline PET-CT and were evaluated serially during their disease course using peak standardized uptake values above background red marrow signal. We demonstrate that the presence of more than 3 focal lesions at presentation identifies a group of patients with an adverse progression-free survival and overall survival. At day 7 of therapy, patients with complete focal lesion signal suppression revert to the same prognosis as those with no lesions at diagnosis. At later time points, the continued suppression of signal remains prognostically important. We conclude that for newly diagnosed patients with focal lesions, treatment until these lesions are suppressed is an important therapeutic goal as the prognosis of these patients is the same as those without lesions at diagnosis. (clinicaltrials.gov identifiers: 00734877, 02128230, 00869232, 00871013).

Hybrid Strategy for High-Risk Neonates with Interrupted Aortic Arch: A Can Well Worth Kicking?

The use of hybrid techniques to avoid neonatal cardiopulmonary bypass in high-risk individuals is well reported in the setting of hypoplastic left heart syndrome. We describe the use of that technique as a bridging procedure in high-risk neonates with an interrupted aortic arch. We report three cases where hybrid branch pulmonary artery banding and ductal stent implantation has been successfully used to defer complete repair, allowing recovery, maturity, and weight gain. This strategy may be considered for patients deemed at high risk for primary neonatal repair.

Loss of heterozygosity as a marker of homologous repair deficiency in multiple myeloma: a role for PARP inhibition?

PARP inhibitors can induce synthetic lethality in tumors characterized by homologous recombination deficiency (HRD), which can be detected by evaluating genome-wide loss of heterozygosity (LOH). Multiple myeloma (MM) is a genetically unstable tumor and we hypothesized that HRD-related LOH (HRD-LOH) could be detected in patient samples, supporting a potential role for PARP inhibition in MM. Using results from targeted next-generation sequencing studies (FoundationOne^® Heme), we analyzed HRD-LOH in patients at all disease stages (MGUS (n = 7), smoldering MM (SMM, n = 30), newly diagnosed MM (NDMM, n = 71), treated MM (TRMM, n = 64), and relapsed MM (RLMM, n = 234)) using an algorithm to identify HRD-LOH segments. We demonstrated HRD-LOH in MM samples, increasing as disease progresses. The extent of genomic HRD-LOH correlated with high-risk disease markers. Outcome of RLMM patients, the biggest clinical group, was analyzed and patients with HRD-LOH above the third quartile (≥5% HRD-LOH) had significantly worse progression-free and overall survival than those with lower levels (p < 0.001). Mutations in key homologous recombination genes account for some, but not all, of the cases with an excess of HRD-LOH. These data support the further evaluation of PARP inhibitors in MM patients, particularly in the relapsed setting with a high unmet need for new treatments.

Pulmonary Regurgitation- Is the Future Percutaneous or Surgical?

For decades, surgical replacement of the pulmonary valve has been seen as the gold-standard technique. Until the advent of Medtronic's Melody valve, it was the only option. Whilst radical changes in surgical techniques have not been forthcoming, rapid and substantial developments in the techniques and available technology for percutaneous valves now cause us to ask if the gold-standard moniker now belongs in the cath lab. This manuscript explores the recent history and future of a revolution in this large area of congenital cardiac practice.

Serial Versus Direct Dilation of Small Diameter Stents Results in a More Predictable and Complete Intentional Transcatheter Stent Fracture: A PICES Bench Testing Study

Balloon-expandable stents, implanted in infants and children with congenital heart disease (CHD), often require redilation to match somatic growth. Small diameter stents may eventually require longitudinal surgical transection to prevent iatrogenic vascular stenosis. Intentional transcatheter stent fracture (TSF) is an emerging alternative approach to stent transection, but little is known about the optimal stent substrate and best protocol to improve the likelihood of successful TSF. Bench testing was performed with a stent dilation protocol. After recording baseline characteristics, stents were serially or directly dilated using ultra-high-pressure balloons (UHPB) until fracture occurred or further stent dilation was not possible. Stent characteristics recorded were as follows: cell design, metallurgy, mechanism, and uniformity of fracture. Stents tested included bare-metal coronary stents, premounted small diameter stents, and ePTFE-covered small diameter premounted stents. Ninety-four stents representing 9 distinct models were maximally dilated, with 80 (85%) demonstrating evidence of fracture. Comprehensive fracture details were recorded in 64 stents: linear and complete in 34/64 stents (53.1%), linear and incomplete in 9/64 stents (14.1%), transverse/complex and complete in 6/64 stents (9.4%), and transverse/complex and incomplete in 15/64 stents (23.4%). Stent fracture was not accomplished in some stent models secondary to significant shortening, i.e., "napkin-ring" formation. Serial dilation resulted in evidence of fracture in 62/67 (92.5%) stents compared with 18/27 (66.7%) stents in the direct dilation group (p = 0.003). Intentional TSF is feasible in an ex vivo model. Serial dilation more reliably expanded the stent and allowed for ultimate stent fracture, whereas direct large diameter dilation of stents was more likely to generate a "napkin-ring" configuration, which may be more resistant to fracture. In vivo animal and human testing is necessary to better understand the response to attempted TSF for newly developed stents as well as those currently in use.

Symptomatic partial and transitional atrioventricular septal defect repaired in infancy

Objectives

Infants with symptomatic partial and transitional atrioventricular septal defect undergoing early surgical repair are thought to be at greater risk. However, the outcome and risk profile of this cohort of patients are poorly defined. The aim of this study was to investigate the outcome of symptomatic infants undergoing early repair and to identify risk factors which may predict mortality and reoperation.

Methods

This multicentre study recruited 51 patients (24 female) in three tertiary centres between 2000 and 2015. The inclusion criteria were as follows: (1) partial and transitional atrioventricular septal defect, (2) heart failure unresponsive to treatment, (3) biventricular repair during the first year of life.

Results

Median age at definitive surgery was 179 (range 0–357) days. Sixteen patients (31%) had unfavourable anatomy of the left atrioventricular valve: dysplastic (n=7), double orifice (n=3), severely deficient valve leaflets (n=1), hypoplastic left atrioventricular orifice and/or mural leaflet (n=3), short/poorly defined chords (n=2). There were three inhospital deaths (5.9%) after primary repair. Eleven patients (22%) were reoperated at a median interval of 40 days (4 days to 5.1 years) for severe left atrioventricular valve regurgitation and/or stenosis. One patient required mechanical replacement of the left atrioventricular valve. After median follow-up of 3.8 years (0.1–11.4 years), all patients were in New York Heart Association (NYHA) class I. In multivariable analysis, unfavourable anatomy of the left atrioventricular valve was the only risk factor associated with left atrioventricular valve reoperation.

Conclusions

Although surgical repair is successful in the majority of the cases, patients with partial and transitional atrioventricular septal defect undergoing surgical repair during infancy experience significant morbidity and mortality. The reoperation rate is high with unfavourable left atrioventricular valve anatomy.

Incomplete Refolding of Antibody Light Chains to Non-Native, Protease-Sensitive Conformations Leads to Aggregation: A Mechanism of Amyloidogenesis in Patients?

Genetic, biochemical, and pharmacologic evidence supports the hypothesis that conformationally altered or misfolded protein states enable aggregation and cytotoxicity in the systemic amyloid diseases. Reversible structural fluctuations of natively folded proteins are involved in the aggregation of many degenerative disease associated proteins. Herein, we use antibody light chains (LCs) that form amyloid fibrils in AL amyloidosis to consider an alternative hypothesis of amyloidogenesis: that transient unfolding and incomplete extracellular refolding of secreted proteins can lead to metastable, alternatively folded states that are more susceptible to aggregation or to endoproteolysis that can release aggregation-prone fragments. Refolding of full-length λ6a LC dimers comprising an interchain disulfide bond from heat- or chaotrope-denatured ensembles in buffers yields the native dimeric state as well as alternatively folded dimers and aggregates. LC variants lacking an interchain disulfide bond appear to refold fully reversibly to the native state. The conformation of a backbone peptidyl-proline amide in the LC constant domain, which is cis in the native state, may determine whether the LC refolds back to the native state. A proline to alanine (P147A) LC variant, which cannot form the native cis-amide conformation, forms amyloid fibrils from the alternatively folded ensemble, whereas all the full-length λ6a LCs we have studied to date do not form amyloid under analogous conditions. P147A LC variants are susceptible to endoproteolysis by thrombin, enabling amyloidogenesis of the fragments released. Thus, non-native LC structural ensembles containing a tyrosine 146-proline 147 trans-amide bond can initiate and propagate amyloid formation, either directly or after aberrant endoproteolysis.

Translation efficiency is maintained at elevated temperature in Escherichia coli

Cellular protein levels are dictated by the balance between gene transcription, mRNA translation, and protein degradation, among other factors. Translation requires the interplay of several RNA hybridization processes, which are expected to be temperature-sensitive. We used ribosome profiling to monitor translation in Escherichia coli at 30 °C and to investigate how this changes after 10-20 min of heat shock at 42 °C. Translation efficiencies are robustly maintained after thermal heat shock and after mimicking the heat-shock response transcriptional program at 30 °C by overexpressing the heat shock σ factor encoded by the rpoH gene. We compared translation efficiency, the ratio of ribosome footprint reads to mRNA reads for each gene, to parameters derived from gene sequences. Genes with stable mRNA structures, non-optimal codon use, and those whose gene product is cotranslationally translocated into the inner membrane are generally less highly translated than other genes. Comparison with other published datasets suggests a role for translational elongation in coupling mRNA structures to translation initiation. Genome-wide calculations of the temperature dependence of mRNA structure predict that relatively few mRNAs show a melting transition between 30 and 42 °C, consistent with the observed lack of changes in translation efficiency. We developed a linear model with six parameters that can predict 38% of the variation in translation efficiency between genes, which may be useful in interpreting transcriptome data.

Response comparison of multiple myeloma and monoclonal gammopathy of undetermined significance to the same anti-myeloma therapy: a retrospective cohort study

BACKGROUND

Multiple myeloma is consistently preceded by monoclonal gammopathy of undetermined significance (MGUS), which is usually only treated by a form of anti-multiple myeloma therapy if it is causing substantial disease through deposition of secreted M proteins. However, studies comparing how MGUS and multiple myeloma plasma cell clones respond to these therapies are scarce. Biclonal gammopathy multiple myeloma is characterised by the coexistence of an active multiple myeloma clone and a benign MGUS clone, and thus provides a unique model to assess the responses of separate clones to the same anti-multiple myeloma therapy, in the same patient, at the same time. We aimed to identify how MGUS and multiple myeloma plasma cell clones responded to anti-multiple myeloma therapy in patients newly diagnosed with biclonal gammopathy multiple myeloma.

METHODS

In this retrospective cohort study, we identified patients with biclonal gammopathy multiple myeloma by central laboratory analysis of 6399 newly diagnosed patients with multiple myeloma enrolled in three UK clinical trials (Myeloma IX, Myeloma XI, and TEAMM) between July 7, 2004, and June 2, 2015. In addition to the inclusion criteria of these trials, our study necessitated at trial entry the presence of two distinct M proteins in immunofixation electrophoresis. The primary endpoint was difference in response achieved with anti-multiple myeloma therapy on MGUS (which we defined as M2) and multiple myeloma (M1) clones-overall, within patients, and between therapy types-with international therapy response criteria assessed with χ² analyses. We analysed by intention to treat.

FINDINGS

44 patients with biclonal gammopathy multiple myeloma with IgG or IgA MGUS clones were subsequently identified from the three trials and then longitudinally monitored. 41 (93%) of M1 clones had a response to therapy (either complete response, very good partial response, partial response, or minor response) compared with only 28 (64%) of M2 clones (p=0·0010). For the 20 patients who received intensive therapy, there was no difference between the proportion of responding clones in M1 (19 [95%]) and M2 (15 [75%], p=0·13). However, for the 17 patients who received non-intensive therapy, 16 (94%) of M1 clones had a response compared with ten [59%] of M2 clones (p=0·031). When examining clones within the same patient, 30 (68%) of 44 individual patients had different levels of responses within the M1 and M2 clones. One patient exhibited M2 progression to myeloma and subsequently died.

INTERPRETATION

These results show that, in patients with biclonal gammopathy multiple myeloma, anti-multiple myeloma therapies exert a greater depth of response against multiple myeloma plasma cell clones than MGUS plasma cell clones. Although some MGUS clones exhibited a complete response, many did not respond, which suggests that the underlying features that render multiple myeloma plasma cells susceptible to therapy are present in only some MGUS plasma cell clones. To determine MGUS clone susceptibly to therapy, future studies might seek to identify, with biclonal gammopathy multiple myeloma as an investigative model, the genetic and epigenetic alterations that affect whether MGUS plasma cell clones are responsive to anti-multiple myeloma therapy.

FUNDING

National Institute of Health Research, Medical Research Council, and Cancer Research UK.