Cancer cell transmission via the placenta

Cancer cells have a parasitic propensity in the primary host but their capacity to transit between individuals is severely restrained by two factors: a lack of a route for viable cell transfer and immune recognition in allogeneic, secondary recipients. Several examples of transmissible animal cancers are now recognised. In humans, the only natural route for transmission is via the haemochorial placenta which is permissive for cell traffic. There are three special examples of this occurring in utero: maternal to foetus, intraplacental twin to twin leukaemias and choriocarcinoma-extra-embryonic cells to mother. We discuss the rare circumstances under which such transmission occurs.

Genome-wide association study identifies susceptibility loci for B-cell childhood acute lymphoblastic leukemia

Genome-wide association studies (GWAS) have advanced our understanding of susceptibility to B-cell precursor acute lymphoblastic leukemia (BCP-ALL); however, much of the heritable risk remains unidentified. Here, we perform a GWAS and conduct a meta-analysis with two existing GWAS, totaling 2442 cases and 14,609 controls. We identify risk loci for BCP-ALL at 8q24.21 (rs28665337, P = 3.86 × 10-9, odds ratio (OR) = 1.34) and for ETV6-RUNX1 fusion-positive BCP-ALL at 2q22.3 (rs17481869, P = 3.20 × 10-8, OR = 2.14). Our findings provide further insights into genetic susceptibility to ALL and its biology.

Nothing in cancer makes sense except…

Paraphrasing Dobzhansky’s famous dictum, I discuss how interrogating cancer through the lens of evolution has transformed our understanding of its development, causality and treatment resistance. The emerging picture of cancer captures its extensive diversity and therapeutic resilience, highlighting the need for more innovative approaches to control.

Prothrombotic Genotypes Are not Associated with Pre-eclampsia and Gestational Hypertension: Results from a Large Population-based Study and Systematic Review

DNA samples collected as part of a large population-based casecontrol study were genotyped to examine the associations of five prothrombotic gene polymorphisms with pre-eclampsia (PE) and gestational hypertension (GH). The polymorphisms studied were: G1691A in Factor V (Factor V Leiden; FVL), prothrombin G20210A, methylenetetrahydrofolate reductase (MTHFR) C677T, plasminogen activator inhibitor-1 4G/5G and the platelet collagen receptor α2β1 C807T. A group of 404 women who developed PE were retrospectively compared with 303 women with GH and 164 control women. The frequency of genotypes did not differ significantly between cases of PE or GH and controls for any of the five polymorphisms studied. We conclude that these prothrombotic genotypes are not associated with the development of PE or GH in our population. The systematic review supports our conclusion, for all but cases of severe disease, which appear to be associated with FVL and, to a lesser extent, MTHFR C677T. There is little value in antenatal screening for prothrombotic polymorphisms to predict the development of pre-eclampsia or gestational hypertension.

Classifying the evolutionary and ecological features of neoplasms

Neoplasms change over time through a process of cell-level evolution, driven by genetic and epigenetic alterations. However, the ecology of the microenvironment of a neoplastic cell determines which changes provide adaptive benefits. There is widespread recognition of the importance of these evolutionary and ecological processes in cancer, but to date, no system has been proposed for drawing clinically relevant distinctions between how different tumours are evolving. On the basis of a consensus conference of experts in the fields of cancer evolution and cancer ecology, we propose a framework for classifying tumours that is based on four relevant components. These are the diversity of neoplastic cells (intratumoural heterogeneity) and changes over time in that diversity, which make up an evolutionary index (Evo-index), as well as the hazards to neoplastic cell survival and the resources available to neoplastic cells, which make up an ecological index (Eco-index). We review evidence demonstrating the importance of each of these factors and describe multiple methods that can be used to measure them. Development of this classification system holds promise for enabling clinicians to personalize optimal interventions based on the evolvability of the patient's tumour. The Evo- and Eco-indices provide a common lexicon for communicating about how neoplasms change in response to interventions, with potential implications for clinical trials, personalized medicine and basic cancer research.

Abstract 4884: Focal 22q11.22 deletions combined with IKZF1 alterations are associated with worse clinical outcome in acute lymphoblastic leukemia

Introduction: Prognostic biomarkers in childhood acute lymphoblastic leukemia (ALL) are vital for risk-stratification and intensifying therapy for children at high risk for remission induction failure or relapse. Copy number alterations in genes such as IKZF1 and VPREB1 have been shown to correlate with poor outcome in ALL, highlighting genetic alterations as prognostic markers (NEJM 360:470, 2009, Leukemia 28(1):216-20, 2014). A second focal deletion in chromosome 22q11.22, 200 kilobases (Kb) in length, occurs more frequently and in the same IGLL region as VPREB1 and is distinct from deletions associated with physiologic IGLL rearrangement. We further investigated this novel genomic lesion, 22q11.22, and the prevalence of co-occurrence with IKZF1.

Methods: 22q11.22 deletions were characterized in a compiled childhood ALL cohort (N=832) and correlated with available clinical outcome using multiple previously published studies (Clinical outcome total N=730; Utah Cohort [N=56], TARGET P9906 cohort [N=215], St. Jude Children's Research Hospital cohort [SJCRH, N=236], Children’s Hospital of Philadelphia cohort [CHOP, N=160], and Down Syndrome cohort [DS, N=63]). Microarray data was analyzed (Utah = Molecular Inversion Probe 330K [Affymetrix]; TARGET = SNP 500K [Affymetrix]; SJCRH = SNP 500K/6.0 [Affymetrix], CHOP = 850K, 610K, and Omni Quadv1 [Illumina], DS = SNP 500K, MIP 330K [Affymetrix]) by Nexus Copy Number (BioDiscovery, Inc.).

Results: ALL patients that harbored copy number deletion 22q11.22 were present in about 30-45% of each cohort: Utah = 42.8%, TARGET = 29%, SJCRH = 40%, CHOP = 34%, DS = 46.7%. The majority of deletions, 93%, had a common recurring region just under 12 Kb in length. The 12 Kb deleted segment encodes no known genes. Patients that harbored a combined deletion in both IKZF1 and 22q11.22 (IKZF1+22q) were present in about 10-15% of each cohort: Utah = 12.5%, TARGET = 18%, SJCRH = 8.4%, CHOP = 6.3%, DS = 14.4%. IKZF1+22q conferred worse event-free survival (N=730, P=0.0062) compared to those with only IKZF1 deletions and worse overall survival (N=507, P=0.0365). Additionally, those patients with IKZF1+22q losses had a median decrease in event-free survival compared to those patients with neither deletion (normal cases): TARGET (high risk cohort) = 0.63 years, P=<0.0001, SJCRH (standard, low risk cohort) = 10 years, P=<0.0001, DS = 2.3 years, P=<0.0001.

Conclusion: We present further evidence that non-physiological deletions within the IGLL locus is associated with worse outcome in pediatric ALL and combined with IKZF1, these double deletions identify a population of patients with very poor outcomes. These combined alterations may be useful to identify patients in the future for high risk stratification and further work is now needed to understand the mechanism and biological consequence of this common loss at 22q11.22 in childhood ALL.

Citation Format: Julia A. Meyer, Clint C. Mason, Luke Maese, Deqing Pei, Cheng Cheng, Ching-Hon Pui, Mel Greaves, Richard Aplenc, Charles G. Mulligan, Elizabeth Raetz, Rodney R. Miles, Karen R. Rabin, Joshua D. Schiffman. Focal 22q11.22 deletions combined with IKZF1 alterations are associated with worse clinical outcome in acute lymphoblastic leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4884. doi:10.1158/1538-7445.AM2017-4884

Carbon dating cancer: defining the chronology of metastatic progression in colorectal cancer

Background

Patients often ask oncologists how long a cancer has been present before causing symptoms or spreading to other organs. The evolutionary trajectory of cancers can be defined using phylogenetic approaches but lack of chronological references makes dating the exact onset of tumours very challenging.

Patients and methods

Here, we describe the case of a colorectal cancer (CRC) patient presenting with synchronous lung metastasis and metachronous thyroid, chest wall and urinary tract metastases over the course of 5 years. The chest wall metastasis was caused by needle tract seeding, implying a known time of onset. Using whole genome sequencing data from primary and metastatic sites we inferred the complete chronology of the cancer by exploiting the time of needle tract seeding as an in vivo 'stopwatch'. This approach allowed us to follow the progression of the disease back in time, dating each ancestral node of the phylogenetic tree in the past history of the tumour. We used a Bayesian phylogenomic approach, which accounts for possible dynamic changes in mutational rate, to reconstruct the phylogenetic tree and effectively 'carbon date' the malignant progression.

Results

The primary colon cancer emerged between 5 and 8 years before the clinical diagnosis. The primary tumour metastasized to the lung and the thyroid within a year from its onset. The thyroid lesion presented as a tumour-to-tumour deposit within a benign Hurthle adenoma. Despite rapid metastatic progression from the primary tumour, the patient showed an indolent disease course. Primary cancer and metastases were microsatellite stable and displayed low chromosomal instability. Neo-antigen analysis suggested minimal immunogenicity.

Conclusion

Our data provide the first in vivo experimental evidence documenting the timing of metastatic progression in CRC and suggest that genomic instability might be more important than the metastatic potential of the primary cancer in dictating CRC fate.

A genome-wide association study identifies risk loci for childhood acute lymphoblastic leukemia at 10q26.13 and 12q23.1

Genome-wide association studies (GWASs) have shown that common genetic variation contributes to the heritable risk of childhood acute lymphoblastic leukemia (ALL). To identify new susceptibility loci for the largest subtype of ALL, B-cell precursor ALL (BCP-ALL), we conducted a meta-analysis of two GWASs with imputation using 1000 Genomes and UK10K Project data as reference (totaling 1658 cases and 7224 controls). After genotyping an additional 2525 cases and 3575 controls, we identify new susceptibility loci for BCP-ALL mapping to 10q26.13 (rs35837782, LHPP, P=1.38 × 10-11) and 12q23.1 (rs4762284, ELK3, P=8.41 × 10-9). We also provide confirmatory evidence for the existence of independent risk loci at 9p21.3, but show that the association marked by rs77728904 can be accounted for by linkage disequilibrium with the rare high-impact CDKN2A p.Ala148Thr variant rs3731249. Our data provide further insights into genetic susceptibility to ALL and its biology.

ETV6-RUNX1 + Acute Lymphoblastic Leukaemia in Identical Twins

Acute leukaemia is the major subtype of paediatric cancer with a cumulative risk of 1 in 2000 for children up to the age of 15 years. Childhood acute lymphoblastic leukaemia (ALL) is a biologically and clinically diverse disease with distinctive subtypes; multiple chromosomal translocations exist within the subtypes and each carries its own prognostic relevance. The most common chromosome translocation observed is the t(12;21) that results in an in-frame fusion between the first five exons of ETV6 (TEL) and almost the entire coding region of RUNX1 (AML1).The natural history of childhood ALL is almost entirely clinically silent and is well advanced at the point of diagnosis. It has, however, been possible to backtrack this process through molecular analysis of appropriate clinical samples: (i) leukaemic clones in monozygotic twins that are either concordant or discordant for ALL; (ii) archived neonatal blood spots or Guthrie cards from individuals who later developed leukaemia; and (iii) stored, viable cord blood cells.Here, we outline our studies on the aetiology and pathology of childhood ALL that provide molecular evidence for a monoclonal, prenatal origin of ETV6-RUNX1+ leukaemia in monozygotic identical twins. We provide mechanistic support for the concept that altered patterns of infection during early childhood can deliver the necessary promotional drive for the progression of ETV6-RUNX1+ pre-leukaemic cells into a postnatal overt leukaemia.

An observational study of direct oral anticoagulant awareness indicating inadequate recognition with potential for patient harm

Essentials Ignorance of direct oral anticoagulants' effects on coagulation tests may be a safety issue. An electronic questionnaire was sent to prescribers in NHS Grampian with 143 respondents. We found widespread evidence of inappropriate interpretation of the clinical scenarios given. The study suggests potential for patient harm due to lack of knowledge and education is required.

SUMMARY

Background Lack of awareness of the nature of the direct oral anticoagulants (DOACs) combined with the poor correlation between routine coagulation test prolongation and the activity of these drugs represents a potential for patient harm. Objectives To establish the level of awareness of the different DOACs, and to assess whether prescribers were able to recognize the state of anticoagulation in a hypothetical patient. Methods and results An electronic questionnaire was sent by email to prescribers in our health board. Among 143 respondents, we found significant differences in awareness of the currently licensed drugs. Of the respondents, 88%, 80% and 50%, respectively, recognized rivaroxaban, dabigatran, and apixaban. When provided with a routine clinical situation, only 13.5%, 17.5% and 16.8%, respectively, recognized that the hypothetical patient was anticoagulated, and only 55-58% recognized that it was unsafe to proceed with an invasive procedure. Conclusion These results indicate a significant risk for patient harm related to lack of knowledge about this new group of frequently used drugs, and indicate that additional education and training on this subject are required.

Leukaemia 'firsts' in cancer research and treatment

Our understanding of cancer biology has been radically transformed over recent years with a more realistic grasp of its multilayered cellular and genetic complexity. These advances are being translated into more selective and effective treatment of cancers and, although there are still considerable challenges, particularly with drug resistance and metastatic disease, many patients with otherwise lethal malignancies now enjoy protracted remissions or cure. One largely unheralded theme of this story is the extent to which new biological insights and novel clinical applications have their origins with leukaemia and related blood cell cancers, including lymphoma. In this Timeline article, I review the remarkable and ground-breaking role that studies in leukaemia have had at the forefront of this progress.

Infection and the Perils of B-cell Activation

Recent studies have linked aberrant B-cell activation in the context of aberrant immune responses to infectious pathogens to malignant transformation and development of leukemia and lymphoma. A new study in this issue demonstrates that common infections can be drivers of clonal evolution of premalignant B-cell precursors toward childhood leukemia.

The 9p21.3 risk of childhood acute lymphoblastic leukaemia is explained by a rare high-impact variant in CDKN2A

Genome-wide association studies (GWAS) have provided strong evidence for inherited predisposition to childhood acute lymphoblastic leukaemia (ALL) identifying a number of risk loci. We have previously shown common SNPs at 9p21.3 influence ALL risk. These SNP associations are generally not themselves candidates for causality, but simply act as markers for functional variants. By means of imputation of GWAS data and subsequent validation SNP genotyping totalling 2,177 ALL cases and 8,240 controls, we have shown that the 9p21.3 association can be ascribed to the rare high-impact CDKN2A p.Ala148Thr variant (rs3731249; Odds ratio = 2.42, P = 3.45 × 10(-19)). The association between rs3731249 genotype and risk was not specific to particular subtype of B-cell ALL. The rs3731249 variant is associated with predominant nuclear localisation of the CDKN2A transcript suggesting the functional effect of p.Ala148Thr on ALL risk may be through compromised ability to inhibit cyclin D within the cytoplasm.