Primary Founder Mutations in the PRKDC Gene Increase Tumor Mutation Load in Colorectal Cancer

The clonal composition of a malignant tumor strongly depends on cellular dynamics influenced by the asynchronized loss of DNA repair mechanisms. Here, our aim was to identify founder mutations leading to subsequent boosts in mutation load. The overall mutation burden in 591 colorectal cancer tumors was analyzed, including the mutation status of DNA-repair genes. The number of mutations was first determined across all patients and the proportion of genes having mutation in each percentile was ranked. Early mutations in DNA repair genes preceding a mutational expansion were designated as founder mutations. Survival analysis for gene expression was performed using microarray data with available relapse-free survival. Of the 180 genes involved in DNA repair, the top five founder mutations were in PRKDC (n = 31), ATM (n = 26), POLE (n = 18), SRCAP (n = 18), and BRCA2 (n = 15). PRKDC expression was 6.4-fold higher in tumors compared to normal samples, and higher expression led to longer relapse-free survival in 1211 patients (HR = 0.72, p = 4.4 × 10−3). In an experimental setting, the mutational load resulting from UV radiation combined with inhibition of PRKDC was analyzed. Upon treatments, the mutational load exposed a significant two-fold increase. Our results suggest PRKDC as a new key gene driving tumor heterogeneity.

Machine learning guided design of high affinity ACE2 decoys for SARS-CoV-2 neutralization

A potential therapeutic candidate for neutralizing SARS-CoV-2 infection is engineering high- affinity soluble ACE2 decoy proteins to compete for binding of the viral spike (S) protein. Previously, a deep mutational scan of ACE2 was performed and has led to the identification of a triple mutant ACE2 variant, named ACE22.v.2.4, that exhibits nanomolar affinity binding to the RBD domain of S. Using a recently developed transfer learning algorithm, TLmutation, we sought to identified other ACE2 variants, namely double mutants, that may exhibit similar binding affinity with decreased mutational load. Upon training a TLmutation model on the effects of single mutations, we identified several ACE2 double mutants that bind to RBD with tighter affinity as compared to the wild type, most notably, L79V;N90D that binds RBD with similar affinity to ACE22.v.2.4. The successful experimental validation of the double mutants demonstrated the use transfer and supervised learning approaches for engineering protein-protein interactions and identifying high affinity ACE2 peptides for targeting SARS-CoV-2.

Mitochondria-mediated Maternal-fetal Interactions and Consequences of Mitochondrial Dysregulation Indicate New Roles for Mitochondria in Hypertensive Pregnancies

Oxidative stress, placental mitochondrial morphological alterations, and impaired bioenergetics are associated with hypertensive disorders of pregnancy. Here we examined mitochondrial DNA mutational load in pregnant women with pregnancy-induced hypertension and reanalyzed publicly available high-throughput transcriptomic datasets from maternal and fetal tissues from normotensive and hypertensive pregnancies. Mitochondrial dysregulation was indicated by aberrant mitochondrial gene expression, and putative consequences were examined. Women with hypertensive pregnancy had elevated mitochondrial DNA mutational load. Maternal mitochondrial dysregulation in hypertensive pregnancies was associated with pathways involved in inflammation, cell death/survival, and placental development. In fetal tissues from hypertensive pregnancies, mitochondrial dysregulation was associated with increased extracellular vesicle production. Our study demonstrates mitochondria-mediated maternal-fetal interactions during healthy pregnancy and maternal mitochondrial dysregulation in hypertensive pregnancy development.

Mutational signatures among young-onset testicular cancers

Background Incidence of testicular cancer is highest among young adults and has been increasing dramatically for men born since 1945. This study aimed to elucidate the factors driving this trend by investigating differences in mutational signatures by age of onset. Methods We retrieved somatic variant and clinical data pertaining to 135 testicular tumors from The Cancer Genome Atlas. We compared mutational load, prevalence of specific mutated genes, mutation types, and mutational signatures between age of onset groups (< 30 years, 30–39 years, ≥ 40 years) after adjusting for subtype. A recursively partitioned mixture model was utilized to characterize combinations of signatures among the young-onset cases. Results Mutational load was significantly higher among older-onset tumors (p < 0.05). There were no highly prevalent driver mutations among young-onset tumors. Mutated genes and types of nucleotide mutations were not significantly different by age group (p > 0.05). Signatures 1, 8 and 29 were more common among young-onset tumors, while signatures 11 and 16 had higher prevalence among older-onset tumors (p < 0.05). Among young-onset tumors, clustering of signatures resulted in four distinct tumor classes. Conclusions Signature contributions differ by age with signatures 1, 8 and 29 were more common among younger-onset tumors. While these signatures are connected with endogenous deamination of 5-methylcytosine, late replication errors and chewing tobacco, respectively, additional research is needed to further elucidate the etiology of young-onset testicular cancer. Large studies of mutational signatures among young-onset patients are required to understand epidemiologic trends as well as inform targeted prevention and treatment strategies.

Transcriptional and mutational signatures of the aging germline

Aging is a complex biological process which is accompanied by changes in gene expression and mutational load. In many species including humans, old fathers pass on more paternally-derived de novo mutations, however, the cellular basis and cell types driving this pattern are still unclear. To understand the root causes of this phenomenon, we performed single-cell RNA-sequencing (scRNA-seq) on testes from young and old male Drosophila, as well as genomic sequencing (DNA-seq) on somatic tissue from the same flies. We found that early germ cells from old and young flies have similar mutational loads, but older flies are less able to remove mutations during spermatogenesis. This indicates that germline mutations arise from primarily non-replicative factors, and that the increased mutational load of older males is due to differences in genome maintenance activities such as repairs to DNA damage. We also found that T>A mutations are enriched in older flies, and transcription-related enrichment terms are depleted in older males. Early spermatogenesis-enriched genes have lower dN/dS than late spermatogenesis-enriched genes, supporting the hypothesis that late spermatogenesis is the source of evolutionary innovation. This transcriptional disruption is reflected in the decreased expression of genome maintenance genes in early germ cells of older flies, as well as potentially aberrant transcription of transposable elements in the aging germline. Our results provide novel insights into the transcriptional and mutational signatures of the male germline.

Germinal BRCA-mutation significance in the tumor microenvironment formation Efficacy of PARP inhibition in late-line therapy of metastatic castration-resistant prostate cancer

Metastatic castration-resistant prostate cancer is a difficult problem for a clinical oncologist. In addition, mutations in genes of homologous DNA recombination, including BRCA1/2, suggest an aggressive behavior and therapy resistance. Treatment options for such patients were significantly limited until new drugs - PARP inhibitors have been registered. Nevertheless, there is evidence that BRCA1/2 gene mutations are associated with increased mutational load, neoepitopes formation, increased number of tumor-infiltrating lymphocytes and a response to the immune response checkpoints blockade. Studies have shown that BRCA2-mutated prostate cancer demonstrates high level of immune cells infiltration compared to tumors without mutation, in particular with respect to CD4+, CD8+ and FOXP3+ T-lymphocytes. It should be noted that studies have shown a tendency of CD8+ T-lymphocytes/FOXP3+ T-cells ratio decreasing in BRCA2-mutated tumors. Thus, the mutational status of BRCA2 presumably forms the immune phenotype of prostate cancer with an increase of intratumoral immune cells, but with immunosuppressive properties. At the same time, the use of immune checkpoint blockers in advanced prostate cancer has been unsuccessful in terms of overall survival. Despite the fact that immune checkpoint blocker's efficacy is often associated with a high intracellular CD4+ and CD8+ T lymphocytes, their presence is clearly insufficient for response. Studies showed that PARP inhibitors effect tumor microenvironment significantly. Anti-PD-1/PD-L1 combination with PARP inhibitors is being actively studied due to their properties of modulating the tumor microenvironment. Thus, future immunooncological strategies for primary prostate cancer therapy may include not only an increase in mutational load, but also an impact on the immunosuppressive microenvironment. The article presents clinical cases of 3 brothers, carriers of the germinal BRCA2 c.9371A>T mutation, suffering from prostate cancer with a burdened family history. The disease development under standard therapies was studied and markers of the tumor microenvironment were immunohistochemically evaluated. PARP inhibitor Olaparib efficacy in prostate cancer of older brother in late-line therapy for metastatic castration-resistant disease was analyzed.

The Impact of gain1q on Mutational Structure and Clonal Evolution in a Uniformly Treated High-Risk Series of Patients at First Relapse

Introduction In Multiple Myeloma (MM) the emergence of treatment resistant clones is a characteristic feature of relapse and this is particularly so for high-risk cases. A key driver event mediating progression, risk status and relapse is gain(1q) (1q+). We report on the impact of 1q+ on the genetic profile seen at first relapse in a uniformly treated, newly diagnosed series of 56 patients enrolled to the NCRI Myeloma XI Trial. Methods We included 56 high risk patients, defined as relapse within 30 months of maintenance randomisation (median 19 months, range 8-51). Of the 56 patients, 30 received lenalidomide maintenance and 26 were observed. Whole exome sequencing was conducted at presentation and relapse to a median depth of 122x for tumour samples and 58x for controls. Libraries were prepared using the SureSelectQXT sample prep kit and SureSelect Clinical Research Exome kit. MuTect was used to determine gene variants and SciClone clustering was undertaken to map mutation variant allele frequencies. MANTA was used to determine translocations and Sequenza for copy number aberrations. Clonal structure and mechanisms of clonal evolution were assessed using kernel density estimation of the cancer clonal fraction for all mutations. Wilcoxon matched-pairs signed rank tests (2-sided) were used to determine the significance between paired data sets, including mutational load. Fishers exact test was used to determine the difference between two nominal variables. Results We looked at mutational, structural and clonal evolution events in all patients based on 1q+ status at relapse. At diagnosis, 34% (19/56) patients had evidence of 1q+, increasing to 46% (26/56) at relapse, with all patients harbouring 1q+ at presentation having the lesion at relapse. There was a significantly higher non-synonymous mutational load at relapse in patients with 1q+, 107 vs 126 (p=0.047), compared to those without 1q+, 36 vs 44 (p=0.140). Twenty two genes known to be significant in MM and mutations within the genes known to be important in IMiD mechanism of action were reviewed. Of the patients with 1q+, 92% (24/26) had at least one mutation during the course of the disease, compared to 77% in those without 1q+ (p=0.15). The impact on tumour suppressor gene regions including deletions of chromosome 1p, 13, 14 and 17p was analyzed. Of the patients with 1q+, 77% (20/26) of patients had a deletion of one of these regions during the disease course, compared to 57% (17/30) of patients without 1q+ (p=0.16). At relapse a change in the profile of these lesions was noted in 23% (6/26) patients with 1q+, compared to 20% (6/30) patients without 1q+ (p=1). Translocations involving MYC (t MYC) were also determined and found in 27% (7/26) of patients with 1q+ and 27% (8/30) of patients without (p=1). As with 1q+, t MYC was always preserved at relapse. Mechanisms of evolution leading to relapse were established for all patients. Branching and linear evolution predominated, noted to be the mechanism leading to relapse in 88% (23/26) patients with 1q+ and 83% (25/30) without (p0.71). Stable evolution was noted in the remaining patients. 1q+ occurring as a new event at relapse was associated with branching or linear evolution in all patients (n=7), consistent with a change in clonal structure. Conclusion These data reveal that 1q+ is conserved throughout the disease course, suggesting it imparts a survival advantage and treatment resistant phenotype to the clone(s) containing it. The presence of 1q+ is associated with a significant increase in mutational load at relapse and a greater incidence of tumour suppressor gene structural deletions, mechanisms that may contribute to clonal evolution and therapeutic escape. Disclosures Jones: BMS/Celgene: Other: Conference fees; Janssen: Honoraria. Pawlyn: Celgene / BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees. Weinhold: Sanofi: Honoraria. Walker: Sanofi: Speakers Bureau; Bristol Myers Squibb: Research Funding. Cairns: Merck Sharpe and Dohme: Research Funding; Amgen: Research Funding; Takeda: Research Funding; Celgene / BMS: Other: travel support, Research Funding. Kaiser: AbbVie: Consultancy; Seattle Genetics: Consultancy; BMS/Celgene: Consultancy, Other: Travel support, Research Funding; Amgen: Honoraria; Karyopharm: Consultancy, Research Funding; Pfizer: Consultancy; Janssen: Consultancy, Other: Educational support, Research Funding; GSK: Consultancy; Takeda: Consultancy, Other: Educational support. Cook: Pfizer: Consultancy, Honoraria; Karyopharm: Consultancy, Honoraria; BMS: Consultancy, Honoraria, Research Funding; Sanofi: Consultancy, Honoraria; Oncopeptides: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Roche: Consultancy, Honoraria. Drayson: Abingdon Health: Current holder of individual stocks in a privately-held company. Jackson: oncopeptides: Consultancy; takeda: Consultancy, Honoraria, Research Funding, Speakers Bureau; GSK: Consultancy, Honoraria, Speakers Bureau; J and J: Consultancy, Honoraria, Speakers Bureau; celgene BMS: Consultancy, Honoraria, Research Funding, Speakers Bureau; amgen: Consultancy, Honoraria, Speakers Bureau; Sanofi: Honoraria, Speakers Bureau. Davies: BMS: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Roche: Consultancy, Honoraria. Morgan: BMS: Membership on an entity's Board of Directors or advisory committees; Jansen: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; GSK: Membership on an entity's Board of Directors or advisory committees.

Defining Genomic Probability of Progression to Identify Low-Risk Smoldering Multiple Myeloma

On an average, 1% of monoclonal gammopathy of undermined significance (MGUS) and 10% of smoldering Multiple Myeloma (SMM) progress to symptomatic MM every year within the first five years of diagnosis. The probability of progression significantly decreases for SMM patients after first 5 years. However, a distinct subset of SMM patients progress within 2 years and are re-classified as high-risk patients based on risk markers such as 20/2/20 or certain genomic features. Although recent studies have evaluated the high-risk genomic features for SMM but genomic background of SMM patients who do not progress to MM after long-term follow-up (&gt;= 5 years) has not been described. Here, we evaluated transcriptomic and genomic changes enriched in non-progressor (NP) (no progression after 5 years of follow-up) precursor conditions (N=31) with those progressed within short period of time (N=71) and compared them with changes observed in newly diagnosed MM (N=192). Additionally, using transcriptome, epigenome and whole genome profiling we also studied additional unique samples from 18 patients at their precursor stage as well as when progressed to MM. Overall, we have observed significantly lower mutational load for NP SMM from progressor SMM (median SNV 4900 vs. 7881 p &lt; 3e-04) with high sensitivity (0.83) and specificity (0.65) to separate NP from progressors. We have further developed a deep learning model by using more than 4500 genome wide features using ten-fold cross validation. This model indicated that not only the load but also the patterns of mutations (type, location, frequency) are different between two conditions. We also found that NP samples have significantly lower heterogeneity (p &lt; 0.05). However, progressed samples showed similar mutational load and heterogeneity at precursor stage and MM. Among CNA differences, absence of gain or deletion of chr8 (not involving MYC region) were strong predictor of NP (OR=7.2 95% CI 2.2-24). Focal genomic loss was also significantly lower for NP (p=0.004) which was also reflected by low genome scar score (GSS) (p=0.07). Structural variant and copy number signature analysis also showed that NPs were showing significantly low exposure to non-clustered variable size genomic deletions. We observed similar frequency of primary translocations [t(11;14), t(4;14), and t(14;16)] in both progressor and NP samples as well as newly diagnosed MM. MYC translocation with any partner was not observed in NP samples, whereas 37% of progressor samples had a MYC translocations (OR=12.8). Adding all these differences including chr8 CNAs, MYC translocations, mutation burden, GSS, focal deletions, all driver mutations as well as primary translocations into recursive partitioning model to predict non-progressor SMM, we have identified a simple genomic model only involving chr8 CN changes and overall mutational burden to achieve a high sensitivity (0.82) and specificity (74%). Our transcriptomic analysis measured the distance between progressor and NP SMM as well as MM and found that NP SMM has greater difference with MM which is closer to progressor SMM. We quantified transcriptomic heterogeneity by using molecular degree of perturbation. This analysis showed that consistent with DNA changes, DNA repair pathway and MYC target genes are expressed similarly in NP SMM as in normal plasma cells compared to progressor SMM. Epigenomic analysis yielded 75 SEs regions differentially utilized between precursor and symptomatic MM stage using paired samples. The targeted genes included BMP6, PRDM1, STAT1, SERTAD2 and RAB21 and possibly regulating genes related to oncogenic KRAS activities. In conclusion, we define genomic characterization of non-progressor SMM and our results now provide the basis to develop molecular definition of SMM as well as risk driving features. Disclosures Munshi: Janssen: Consultancy; Pfizer: Consultancy; Legend: Consultancy; Novartis: Consultancy; Adaptive Biotechnology: Consultancy; Oncopep: Consultancy, Current equity holder in publicly-traded company, Other: scientific founder, Patents & Royalties; Takeda: Consultancy; Abbvie: Consultancy; Karyopharm: Consultancy; Amgen: Consultancy; Celgene: Consultancy; Bristol-Myers Squibb: Consultancy.