bims-lifras 2020-10-04 papers

bims-lifras

Biomed News

on Li-Fraumeni syndrome

Issue of 2020‒10‒04
thirteen papers selected by
Joanna Zawacka-Pankau
University of Warsaw

TP53, a gene for colorectal cancer predisposition in the absence of Li-Fraumeni-associated phenotypes.
Gene Panel Tumor Testing in Ovarian Cancer Patients Significantly Increases the Yield of Clinically Actionable Germline Variants beyond BRCA1/BRCA2.
Effects of germline and somatic events in candidate BRCA-like genes on breast-tumor signatures.
New surveillance guidelines for Li-Fraumeni and hereditary TP53 related cancer syndrome: implications for germline TP53 testing in breast cancer.
Comparison of Colorectal and Endometrial Microsatellite Instability Tumor Analysis and Premm5 Risk Assessment for Predicting Pathogenic Germline Variants on Multigene Panel Testing.
Germline variants of Brazilian women with breast cancer and detection of a novel pathogenic ATM deletion in early-onset breast cancer.
Genetic characterization of pancreatic cancer patients and prediction of carrier status of germline pathogenic variants in cancer-predisposing genes.
Comparison Between Familial Colorectal Cancer Type X and Lynch Syndrome: Molecular, Clinical, and Pathological Characteristics and Pedigrees.
First description of ultramutated endometrial cancer caused by germline loss-of-function and somatic exonuclease domain mutations in POLE gene.
Distinctive phenotypes in two children with novel germline RUNX1 mutations - one with myeloid malignancy and increased fetal hemoglobin.
Cancer Predisposition Genes in Cancer-Free Families.
Association between the TPMT*3C (rs1142345) Polymorphism and the Risk of Death in the Treatment of Acute Lymphoblastic Leukemia in Children from the Brazilian Amazon Region.
Survival implications of the relationship between tissue versus circulating tumor DNA TP53 mutations - a perspective from a real-world precision medicine cohort.

Gut. 2020 Sep 30. pii: gutjnl-2020-321825. [Epub ahead of print]

TP53, a gene for colorectal cancer predisposition in the absence of Li-Fraumeni-associated phenotypes.

Terradas M, Mur P, Belhadj S, Woodward ER, Burghel GJ, Munoz-Torres PM, Quintana I, Navarro M, Brunet J, Lazaro C, Pineda M, Moreno V, Capella G, Evans DGR, Valle L.

  OBJECTIVE: Germline TP53 pathogenic (P) variants cause Li-Fraumeni syndrome (LFS), an aggressive multitumor-predisposing condition. Due to the implementation of multigene panel testing, TP53 variants have been detected in individuals without LFS suspicion, for example, patients with colorectal cancer (CRC). We aimed to decipher whether these findings are the result of detecting the background population prevalence or the aetiological basis of CRC.DESIGN: We analysed TP53 in 473 familial/early-onset CRC cases and evaluated the results together with five additional studies performed in patients with CRC (total n=6200). Control population and LFS data were obtained from Genome Aggregation Database (gnomAD V.2.1.1) and the International Agency for Research on Cancer (IARC) TP53 database, respectively. All variants were reclassified according to the guidelines of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG/AMP), following the ClinGen TP53 Expert Panel specifications.
RESULTS: P or likely pathogenic (LP) variants were identified in 0.05% of controls (n=27/59 095) and 0.26% of patients with CRC (n=16/6200) (p<0.0001) (OR=5.7, 95% CI 2.8 to 10.9), none of whom fulfilled the clinical criteria established for TP53 testing. This association was still detected when patients with CRC diagnosed at more advanced ages (>50 and>60 years) were excluded from the analysis to minimise the inclusion of variants caused by clonal haematopoiesis. Loss-of-function and missense variants were strongly associated with CRC as compared with controls (OR=25.44, 95% CI 6.10 to 149.03, for loss of function and splice-site alleles, and OR=3.58, 95% CI 1.46 to 7.98, for missense P or LP variants).
CONCLUSION: TP53 P variants should not be unequivocally associated with LFS. Prospective follow-up of carriers of germline TP53 P variants in the absence of LFS phenotypes will define how surveillance and clinical management of these individuals should be performed.

Keywords:  cancer genetics; cancer susceptibility; cancer syndromes; gene mutation; genetic testing

DOI:  https://doi.org/10.1136/gutjnl-2020-321825
Cancers (Basel). 2020 Sep 30. pii: E2834. [Epub ahead of print]12(10):

Gene Panel Tumor Testing in Ovarian Cancer Patients Significantly Increases the Yield of Clinically Actionable Germline Variants beyond BRCA1/BRCA2.

Barbosa A, Pinto P, Peixoto A, Guerra J, Pinto C, Santos C, Pinheiro M, Escudeiro C, Bartosch C, Silva J, Teixeira MR.

  Since the approval of PARP inhibitors for the treatment of high-grade serous ovarian cancer, in addition to cancer risk assessment, BRCA1 and BRCA2 genetic testing also has therapeutic implications (germline and somatic variants) and should be offered to these patients at diagnosis, irrespective of family history. However, variants in other genes besides BRCA1 and BRCA2 are associated with ovarian cancer predisposition, which would be missed by a genetic testing aimed only at indication for PARP inhibitor treatment. In this study, we aimed to evaluate the yield of clinically actionable germline variants using next-generation sequencing of a customized panel of 10 genes for the analysis of formalin-fixed paraffin-embedded samples from 96 ovarian carcinomas, a strategy that allows the detection of both somatic and germline variants in a single test. In addition to 13.7% of deleterious germline BRCA1/BRCA2 carriers, we identified 7.4% additional patients with pathogenic germline variants in other genes predisposing for ovarian cancer, namely RAD51C, RAD51D, and MSH6, representing 35% of all pathogenic germline variants. We conclude that the strategy of reflex gene-panel tumor testing enables the identification of clinically actionable germline variants in a significantly higher proportion of ovarian cancer patients, which may be valuable information in patients with advanced disease that have run out of approved therapeutic options. Furthermore, this approach increases the chance to make available genetic counseling, presymptomatic genetic testing, and gynecological cancer prophylaxis to female relatives who turn out to be healthy carriers of deleterious germline variants.

Keywords:  clinically actionable alterations; genetic predisposition; multi-gene panel; next generation sequencing; ovarian cancer; tumor testing

DOI:  https://doi.org/10.3390/cancers12102834
PLoS One. 2020 ;15(9): e0239197

Effects of germline and somatic events in candidate BRCA-like genes on breast-tumor signatures.

Bodily WR, Shirts BH, Walsh T, Gulsuner S, King MC, Parker A, Roosan M, Piccolo SR.

Mutations in BRCA1 and BRCA2 cause deficiencies in homologous recombination repair (HR), resulting in repair of DNA double-strand breaks by the alternative non-homologous end-joining pathway, which is more error prone. HR deficiency of breast tumors is important because it is associated with better responses to platinum salt therapies and PARP inhibitors. Among other consequences of HR deficiency are characteristic somatic-mutation signatures and gene-expression patterns. The term "BRCA-like" (or "BRCAness") describes tumors that harbor an HR defect but have no detectable germline mutation in BRCA1 or BRCA2. A better understanding of the genes and molecular events associated with tumors being BRCA-like could provide mechanistic insights and guide development of targeted treatments. Using data from The Cancer Genome Atlas (TCGA) for 1101 breast-cancer patients, we identified individuals with a germline mutation, somatic mutation, homozygous deletion, and/or hypermethylation event in BRCA1, BRCA2, and 59 other cancer-predisposition genes. Based on the assumption that BRCA-like events would have similar downstream effects on tumor biology as BRCA1/BRCA2 germline mutations, we quantified these effects based on somatic-mutation signatures and gene-expression profiles. We reduced the dimensionality of the somatic-mutation signatures and expression data and used a statistical resampling approach to quantify similarities among patients who had a BRCA1/BRCA2 germline mutation, another type of aberration in BRCA1 or BRCA2, or any type of aberration in one of the other genes. Somatic-mutation signatures of tumors having a non-germline aberration in BRCA1/BRCA2 (n = 80) were generally similar to each other and to tumors from BRCA1/BRCA2 germline carriers (n = 44). Additionally, somatic-mutation signatures of tumors with germline or somatic events in ATR (n = 16) and BARD1 (n = 8) showed high similarity to tumors from BRCA1/BRCA2 carriers. Other genes (CDKN2A, CTNNA1, PALB2, PALLD, PRSS1, SDHC) also showed high similarity but only for a small number of events or for a single event type. Tumors with germline mutations or hypermethylation of BRCA1 had relatively similar gene-expression profiles and overlapped considerably with the Basal-like subtype; but the transcriptional effects of the other events lacked consistency. Our findings confirm previously known relationships between molecular signatures and germline or somatic events in BRCA1/BRCA2. Our methodology represents an objective way to identify genes that have similar downstream effects on molecular signatures when mutated, deleted, or hypermethylated.

DOI: https://doi.org/10.1371/journal.pone.0239197
Fam Cancer. 2020 Sep 28.

New surveillance guidelines for Li-Fraumeni and hereditary TP53 related cancer syndrome: implications for germline TP53 testing in breast cancer.

Evans DG, Woodward ER.



Keywords:  Breast cancer; Heritable TP53-related cancer; Li-fraumeni syndrome; MRI; Penetrance; Sarcoma; TP53; Variant

DOI:  https://doi.org/10.1007/s10689-020-00207-z
J Clin Oncol. 2020 Sep 30. JCO2001470

Comparison of Colorectal and Endometrial Microsatellite Instability Tumor Analysis and Premm5 Risk Assessment for Predicting Pathogenic Germline Variants on Multigene Panel Testing.

Mannucci A, Furniss CS, Ukaegbu C, Horiguchi M, Fehlmann T, Uno H, Yurgelun MB, Syngal S.

PURPOSE: Tumor testing for microsatellite instability and/or mismatch repair-deficiency (MSI/IHC) and clinical prediction models effectively screen for Lynch syndrome (LS)-associated colorectal cancer (CRC) and endometrial cancer (EC), but they have not been assessed for their ability to identify non-LS forms of inherited risk. The aim of this study was to compare MSI/IHC and the PREMM5 prediction model to identify carriers of LS and non-LS pathogenic variants (PVs) among patients with CRC and EC.PATIENTS AND METHODS: Data were retrospectively analyzed from two single-institution cohorts: 706 patients with CRC and/or EC referred for genetic evaluation/testing (high-risk cohort) and 1,058 consecutively ascertained patients with CRC (oncology clinic cohort), unselected for familial risk. All participants underwent germline multigene panel testing. PREMM5 scores were calculated from personal/family cancer history. The primary outcome was the proportion of individuals with germline PVs (LS PVs, high-penetrance PVs, and any PVs) who had abnormal MSI/IHC testing and/or PREMM5 score ≥ 2.5%.
RESULTS: MSI/IHC and PREMM5 had comparable sensitivity for identifying LS carriers in high-risk (89.3% v 85.7%; P = .712) and oncology clinic patients (96.6% v 96.6%; P = 1.000), although MSI/IHC had significantly superior specificity for LS (81.3% v 20.1%; P < .001; 92.3% v 24.3%; P < .001). In both cohorts, PREMM5 had superior sensitivity to MSI/IHC at identifying patients with any high-penetrance PVs and any low-, moderate-, and high-penetrance PVs. Among patients with normal MSI/IHC, PREMM5 identified 84.2% and 83.3% of high-risk patients with CRC/EC and oncology clinic CRC patients with high-penetrance PVs, respectively.
CONCLUSION: MSI/IHC and PREMM5 effectively identify patients with CRC and/or EC with LS, although MSI/IHC has better specificity for LS. Because PREMM5 identifies non-LS, high-penetrance germline PVs, patients with CRC and/or EC with PREMM5 score ≥ 2.5%, including those with normal MSI/IHC, should be offered multigene panel testing.

DOI: https://doi.org/10.1200/JCO.20.01470
Breast Cancer. 2020 Sep 28.

Germline variants of Brazilian women with breast cancer and detection of a novel pathogenic ATM deletion in early-onset breast cancer.

Bandeira G, Rocha K, Lazar M, Ezquina S, Yamamoto G, Varela M, Takahashi V, Aguena M, Gollop T, Zatz M, Passos-Bueno MR, Krepischi A, Okamoto OK.

  BACKGROUND: It is estimated that 5-10% of breast cancer cases are hereditary. The identification of pathogenic germline variants allows individualized preventive health care, improvement of clinical management and genetic counseling. Studies in ethnically admixed Latin American populations have identified regions with increased frequency of deleterious variants in breast cancer predisposing genes. In this context, the Brazilian population exhibits great genetic heterogeneity, and is not well represented in international databases, which makes it difficult to interpret the clinical relevance of germline variants.METHODS: We evaluated the frequency of pathogenic/likely pathogenic (P/LP) germline variants in up to 37 breast cancer predisposing genes, in a cohort of 105 breast and/or ovarian cancer Brazilian women referred to two research centers between 2014 and 2019.
RESULTS: A total of 22 patients (21%) were found to carry P/LP variants, and 16 VUS were detected in 15 patients (14.3%). Additionally, a novel pathogenic ATM intragenic deletion was identified in an early-onset breast cancer. We also detected a BRCA1 pathogenic variant (c.5074+2T>C) in higher frequency (10×) than in other studies with similar cohorts.
CONCLUSIONS: Our findings contribute to the characterization of the genetic background of breast cancer predisposition in the Brazilian population as a useful resource to discriminate between deleterious variants and VUS, thus enabling improvement in the preventive health care and clinical management of carriers.

Keywords:  ATM; BRCA1; BRCA2; Breast and ovarian cancer susceptibility; Hereditary breast and ovarian cancer (HBOC)

DOI:  https://doi.org/10.1007/s12282-020-01165-1
EBioMedicine. 2020 Sep 24. pii: S2352-3964(20)30409-6. [Epub ahead of print]60 103033

Genetic characterization of pancreatic cancer patients and prediction of carrier status of germline pathogenic variants in cancer-predisposing genes.

Mizukami K, Iwasaki Y, Kawakami E, Hirata M, Kamatani Y, Matsuda K, Endo M, Sugano K, Yoshida T, Murakami Y, Nakagawa H, Spurdle AB, Momozawa Y.

  BACKGROUND: National Comprehensive Cancer Network (NCCN) recently recommended germline genetic testing for all pancreatic cancer patients. However, the genes targeted by genetic testing and the feasibility of selecting patients likely to carry pathogenic variants have not been sufficiently verified. The purpose of this study was to genetically characterize Japanese patients and examine whether the current guideline is applicable in this population.METHODS: Using targeted sequencing, we analyzed the coding regions of 27 cancer-predisposing genes in 1,005 pancreatic cancer patients and 23,705 controls in Japan. We compared the pathogenic variant frequency between cases and controls and documented the demographic and clinical characteristics of carrier patients. We then examined if it was possible to use machine learning to predict carrier status based on those characteristics.
FINDINGS: We identified 205 pathogenic variants across the 27 genes. Pathogenic variants in BRCA2, ATM, and BRCA1 were significantly associated with pancreatic cancer. Characteristics associated with carrier status were inconsistent with previous investigations. Machine learning classifiers had a low performance in determining the carrier status of pancreatic cancer patients, while the same classifiers, when applied to breast cancer data as a positive control, had a higher performance that was comparable to that of the NCCN guideline.
INTERPRETATION: Our findings support the clinical significance of multigene panel testing for pancreatic cancer and indicate that at least 3.4% of Japanese patients may respond to poly (ADP ribose) polymerase inhibitor treatments. The difficulty in predicting carrier status suggests that offering germline genetic testing for all pancreatic cancer patients is reasonable.
FUNDING: AMED under Grant Number JP19kk0305010 and Australian National Health and Medical Research funding (ID177524).

Keywords:  ATM; BRCA; Machine learning; Pancreatic cancer; Pathogenic variants; Universal screening for patients

DOI:  https://doi.org/10.1016/j.ebiom.2020.103033
Front Oncol. 2020 ;10 1603

Comparison Between Familial Colorectal Cancer Type X and Lynch Syndrome: Molecular, Clinical, and Pathological Characteristics and Pedigrees.

Xu Y, Li C, Zhang Y, Guo T, Zhu C, Xu Y, Liu F.

  Objective: This study aimed to compare the molecular, clinical, and pathological characteristics and pedigrees of familial colorectal cancer type X (FCCTX) with those of Lynch syndrome (LS) to provide a theoretical basis for the management of FCCTX.Methods: Overall, 46 cases of FCCTX and 47 LS probands and affected families were enrolled between June 2008 and September 2018 for this study. Multigene cancer panel tests that included 139 genes were performed for all patients, and variants in each group were described. The clinical, pathological, and pedigree characteristics were also compared between the two groups.
Results: In total, 42 variants were detected in 27 (58.7%) cases in the FCCTX group, with BRCA1, BRCA2, POLE, POLD1, ATR, and ATM being the most frequently mutated genes. The mean onset age of colorectal cancer (CRC) was significantly older in the FCCTX group than in the LS group (53.57 ± 12.88 years vs. 44.36 ± 11.26 years, t = -9.204, p < 0.001). The proportion of patients with rectal cancer was also higher in the FCCTX group than in the LS group [43.5% (20/46) vs. 10.6% (5/47), χ2 = 12.823, p = 0.005]. Within a median follow-up time of 53.9 ± 37.0 months, the proportion of patients who developed metachronous CRC was significantly higher in the LS group than in the FCCTX group [34.0% (16/47) vs. 13.0% (6/46), χ2 = 5.676, p = 0.017]. When comparing pedigrees, older age at cancer onset and rectal cancer clustering were observed in the FCCTX families. A higher prevalence in male patients was also observed in the FCCTX families.
Conclusion: FCCTX is an entity distinct from LS, but its genetic etiology remains unknown. A larger multigene panel would be recommended for determining the underlying pathogenic variants. Considering the pathology and moderate penetrance of the CRC link to FCCTX, less stringent surgical treatments and colonoscopy surveillance would be preferable. Rectum preference is a typical feature of FCCTX. Colonoscopy surveillance in FCCTX families could be less intensive, and more attention should be given to male members.

Keywords:  Lynch syndrome; clinical management; colorectal cancer; familial colorectal cancer type X; mismatch repair

DOI:  https://doi.org/10.3389/fonc.2020.01603
Genet Mol Biol. 2020 ;pii: S1415-47572020000600101. [Epub ahead of print]43(4): e20200100

First description of ultramutated endometrial cancer caused by germline loss-of-function and somatic exonuclease domain mutations in POLE gene.

Rosa RCA, Yurchenko AA, Chahud F, Ribeiro-Silva A, Brunaldi MO, Silva WA, Kannouche PL, Nikolaev S, Ferraz VEF.

Endometrial cancer (EC) harboring heterozygous POLE proofreading inactivating mutations (POLE-exo*) is associated with an increased number of somatic mutations that result in a distinctive anti-tumor immune response. However, the consequences of such POLE mutations in the context of the missing wild-type allele have not yet been described in endometrial tumors. A 72-year-old woman harboring a germline monoallelic frameshift mutation (p.Pro269fsTer26) in POLE was diagnosed with an EC having a somatic heterozygous mutation in the exonuclease domain of POLE (S459F). Targeted gene sequencing revealed an ultramutated phenotype (381 mutations/Mb) in the tumor and a 2-fold excess of mutations on the DNA leading strand. Additionally, we observed a mutational signature similar to the COSMIC signature 10, a higher mutation rate in this tumor than in endometrial tumors with heterozygous POLE-exo*, and an increased number of T lymphocytes. This is the first report of an ultramutated EC harboring a somatic POLE-exo* mutation in association with a germline loss-of-function mutation in this gene. The absence of a wild type POLE allele led to a particularly high mutational burden.

DOI: https://doi.org/10.1590/1678-4685-GMB-2020-0100
Pediatr Hematol Oncol. 2020 Sep 29. 1-15

Distinctive phenotypes in two children with novel germline RUNX1 mutations - one with myeloid malignancy and increased fetal hemoglobin.

Bagla S, Regling KA, Wakeling EN, Gadgeel M, Buck S, Zaidi AU, Flore LA, Chicka M, Schiffer CA, Chitlur MB, Ravindranath Y.

  RUNX1 associated familial platelet disorder (FPD) is a rare autosomal dominant hematologic disorder characterized by thrombocytopenia and/or altered platelet function. There is an increased propensity to develop myeloid malignancy (MM) - acute myeloid leukemia, myeloproliferative neoplasms or myelodysplastic syndrome often in association with secondary somatic variants in other genes. To date, 23 FPD-MM pediatric cases have been reported worldwide. Here, we present two new kindreds with novel RUNX1 pathogenic variants in which children are probands. The first family is a daughter/mother diad, sharing a heterozygous frameshift variant in RUNX1 gene (c.501delT p.Ser167Argfs*9). The daughter, age 13 years, presented with features resembling juvenile myelomonocytic leukemia - severe anemia, thrombocytopenia, high white cell count with blast cells, monocytosis, increased nucleated red cells and had somatic mutations with high allele burden in CUX1, PHF6, and SH2B3 genes. She also had increased fetal hemoglobin and increased LIN28B expression. The mother, who had a long history of hypoplastic anemia, had different somatic mutations- a non-coding mutation in CUX1 but none in PHF6 or SH2B3. Her fetal hemoglobin and LIN28B expression were normal. In the second kindred, the proband, now 4 years old with thrombocytopenia alone, was investigated at 3 months of age for persistent neonatal thrombocytopenia with large platelets. Molecular testing identified a heterozygous intragenic deletion in RUNX1 encompassing exon 5. His father is known to have increased bruising for several years but is unavailable for testing. These two cases illustrate the significance of secondary mutations in the development and progression of RUNX1-FPD to MM.

Keywords:  JMML; LIN28B and Fetal hemoglobin; RUNX1 familial platelet disorder; myeloproliferative disorder; sea blue histiocytes

DOI:  https://doi.org/10.1080/08880018.2020.1814463
Cancers (Basel). 2020 Sep 27. pii: E2770. [Epub ahead of print]12(10):

Cancer Predisposition Genes in Cancer-Free Families.

Zheng G, Catalano C, Bandapalli OR, Paramasivam N, Chattopadhyay S, Schlesner M, Sijmons R, Hemminki A, Dymerska D, Lubinski J, Hemminki K, Försti A.

  Familial clustering, twin concordance, and identification of high- and low-penetrance cancer predisposition variants support the idea that there are families that are at a high to moderate excess risk of cancer. To what extent there may be families that are protected from cancer is unknown. We wanted to test genetically whether cancer-free families share fewer breast, colorectal, and prostate cancer risk alleles than the population at large. We addressed this question by whole-genome sequencing (WGS) of 51 elderly cancer-free individuals whose numerous (ca. 1000) family members were found to be cancer-free ('cancer-free families', CFFs) based on face-to-face interviews. The average coverage of the 51 samples in the WGS was 42x. We compared cancer risk allele frequencies in cancer-free individuals with those in the general population available in public databases. The CFF members had fewer loss-of-function variants in suggested cancer predisposition genes compared to the ExAC data, and for high-risk cancer predisposition genes, no pathogenic variants were found in CFFs. For common low-penetrance breast, colorectal, and prostate cancer risk alleles, the results were not conclusive. The results suggest that, in line with twin and family studies, random environmental causes are so dominant that a clear demarcation of cancer-free populations using genetic data may not be feasible.

Keywords:  high-risk genes; polygenic risk; predisposing genes; random environment

DOI:  https://doi.org/10.3390/cancers12102770
Genes (Basel). 2020 Sep 25. pii: E1132. [Epub ahead of print]11(10):

Association between the TPMT*3C (rs1142345) Polymorphism and the Risk of Death in the Treatment of Acute Lymphoblastic Leukemia in Children from the Brazilian Amazon Region.

Cardoso de Carvalho D, Pereira Colares Leitão L, Mello Junior FAR, Vieira Wanderley A, Souza TP, Borges Andrade de Sá R, Cohen-Paes A, Rodrigues Fernandes M, Santos S, Salim Khayat A, Pimentel de Assumpção P, Pereira Carneiro Dos Santos N.

  Acute lymphoblastic leukemia (ALL) is the leading cause of death from pediatric cancer worldwide. However, marked ethnic disparities are found in the treatment of childhood ALL with less effective results and higher mortality rates being obtained in populations with a high level of Native American ancestry. Genetic variations of the patient can affect resistance to ALL chemotherapy and potentially play an important role in this disparity. In the present study, we investigated the association of 16 genetic polymorphisms with the cell and metabolic pathways of the chemotherapeutic agents used in the treatment of ALL with the risk of death in treating childhood ALL in patients with a high contribution of Amerindian ancestry, coming from the Brazilian Amazon. The study included 121 patients with B-cell ALL treated with the BFM-2002 protocol. We are the first to identify the association between the TPMT gene rs1142345 polymorphism and the high risk of death in treating childhood ALL. Patients with the CC genotype had an approximately 25.5 times higher risk of dying during treatment of the disease than patients with other genotypes (p = 0.019). These results may help elucidate how the patient's genetic characteristics contribute to the mortality disparity in populations with a high contribution of Native American ancestry. The rs1142345 variant of the TPMT gene could be used as a potential marker to early stratify patients at high risk of death in treating childhood ALL in the investigated population.

Keywords:  Amazon; TPMT; acute lymphoblastic leukemia; admixed populations; ancestry; mortality; pediatrics; pharmacogenetics; polymorphism

DOI:  https://doi.org/10.3390/genes11101132
Mol Cancer Ther. 2020 Sep 30. pii: molcanther.0097.2020. [Epub ahead of print]

Survival implications of the relationship between tissue versus circulating tumor DNA TP53 mutations - a perspective from a real-world precision medicine cohort.

Rosenberg S, Okamura R, Kato S, Soussi T, Kurzrock R.

Interrogating the genomics of circulating tumor DNA (ctDNA) (the liquid biopsy) has advantages in patients in whom tissue biopsy is difficult. However, the reported concordance between genomic analysis of tissue DNA and ctDNA is variable among studies. Herein, we characterized the clinical implications of the relationship between mutations in TP53 genes in tissue DNA versus ctDNA. The molecular profiles of both liquid (Guardant Health) and tissue biopsies (Foundation Medicine) from 433 patients were analyzed (pan-cancer setting). In 71/433 (16%) cases, all same TP53 mutations were detected in both tissue DNA and ctDNA; 18/433 (4%), same mutation plus additional mutation/mutations; 27/433 (6%), different TP53 mutations. In 99/433 (23%) cases, TP53 mutations were detected only in tissue DNA; 43/433 (10%), only in ctDNA; and in 175/433 (40%), no TP53 mutations were detected in either test. When TP53 mutations were identical in tissue and ctDNA, the alterations were enriched for nonsense mutations, and survival was significantly shorter in multivariate analysis (as compared to different mutations in ctDNA versus tissue or no mutations); this finding was independent of tumor type, time interval between tests, and the %ctDNA for TP53 mutations. In summary, in 16% of 433 patients with diverse cancers, TP53 mutations were identical in tissue DNA and ctDNA. In these individuals, the alterations were enriched for stop-gain (nonsense) mutations (results in a premature termination codon). Though unknown confounders cannot be ruled out, these patients fared significantly worse than those whose ctDNA and tissue DNA harbored different TP53 mutation portfolios or no TP53 mutations.

DOI: https://doi.org/10.1158/1535-7163.MCT-20-0097