Combined PGT for Breast Cancer and Other Inherited Conditions

Inherited cancer predisposition is presently one of the major indications for preimplantation genetic testing (PGT), providing an option for couplers at risk to avoid the birth of an offspring with predisposition to cancer. We present here our experience of 35 of 874 PGT cycles for cancer, in which in addition to BRCA1/2 the couples were at risk to another genetic conditions as well, for which PGT was performed together with PGT for breast cancer. This resulted in in birth of 20 mutation free children with not only unaffected for the tested genetic condition, but also without risk of developing cancer. This is a part of our overall PGT series of 6,204 PGT cases for monogenic disorders (PGT-M), with 2,517 resulting births, free of genetic disorder. The accumulated experience, demonstrates considerable progress in using PGT for avoiding the birth of affected children together with avoiding predisposition to cancer.

Germline RET Leu56Met Variant Is Likely Not Causative of Multiple Endocrine Neoplasia Type 2

Activating variants in the receptor tyrosine kinase REarranged during Transfection (RET) cause multiple endocrine neoplasia type 2 (MEN 2), an autosomal dominantly inherited cancer-susceptibility syndrome. The variant c.166C>A, p.Leu56Met in RET was recently reported in two patients with medullary thyroid cancer (MTC). The presence of a pheochromocytoma in one of the patients, suggested a possible pathogenic role of the variant in MEN 2A. Here, we present clinical follow up of a Danish RET Leu56Met cohort. Patients were evaluated for signs of MEN 2 according to a set of predefined criteria. None of the seven patients in our cohort exhibited evidence of MEN 2. Furthermore, we found the Leu56Met variant in our in-house diagnostic cohort with an allele frequency of 0.59%, suggesting that it is a common variant in the population. Additionally, none of the patients who harbored the allele were listed in the Danish MTC and MEN 2 registries. In conclusion, our findings do not support a pathogenic role of the Leu56Met variant in MEN 2.

Oligomerization of Mutant p53 R273H is not Required for Gain-of-Function Chromatin Associated Activities

The TP53 gene is often mutated in cancer, with missense mutations found in the central DNA binding domain, and less often in the C-terminal oligomerization domain (OD). These types of mutations are found in patients with the rare inherited cancer predisposition disorder called Li-Fraumeni syndrome. We previously found that mutant p53 (mtp53) R273H associates with replicating DNA and promotes the chromatin association of replication-associated proteins mini-chromosome maintenance 2 (MCM2), and poly ADP-ribose polymerase 1(PARP1). Herein, we created dual mutants in order to test if the oligomerization state of mtp53 R273H played a role in chromatin binding oncogenic gain-of-function (GOF) activities. We used site-directed mutagenesis to introduce point mutations in the OD in wild-type p53 (wtp53), and mtp53 R273H expressing plasmids. The glutaraldehyde crosslinking assay revealed that both wtp53 and mtp53 R273H formed predominantly tetramers, while the single OD mutant A347D, and the dual mtp53 R273H-A347D, formed predominantly dimers. The R337C, L344P, mtp53 R273H-R337C, and mtp53 R273H-L344P proteins formed predominantly monomers. Wtp53 was able to activate the cyclin-dependent kinase gene p21/waf and the p53 feedback regulator MDM2. As expected, the transactivation activity was lost for all the single mutants, as well as the mtp53 R273H-dual mutants. Importantly, mtp53 R273H and the dual oligomerization mutants, R273H-A347D, R273H-R337C, and R273H-L344P were able to interact with chromatin. Additionally, the dual oligomerization mutants, R273H-A347D, R273H-R337C, and R273H-L344P, maintained strong interactions with MCM2 and PARP1. Our findings suggest that while mtp53 R273H can form tetramers, tetramer formation is not required for the GOF associated chromatin interactions.

IMProving care After inherited Cancer Testing (IMPACT) study: protocol of a randomized trial evaluating the efficacy of two interventions designed to improve cancer risk management and family communication of genetic test results

Background Implementing genetic testing for inherited cancer predisposition into routine clinical care offers a tremendous opportunity for cancer prevention and early detection. However, genetic testing itself does not improve outcomes; rather, outcomes depend on implemented follow-up care. The IMPACT study is a hybrid type I randomized effectiveness-implementation trial to simultaneously evaluate the effectiveness of two interventions for individuals with inherited cancer predisposition focused on: 1) increasing family communication (FC) of genetic test results; and 2) improving engagement with guideline-based cancer risk management (CRM). Methods This prospective study will recruit a racially, geographically, and socioeconomically diverse population of individuals with a documented pathogenic/likely pathogenic (P/LP) variant in an inherited cancer gene. Eligible participants will be asked to complete an initial trial survey and randomly assigned to one of three arms: A) GeneSHARE, a website designed to increase FC of genetic test results; B) My Gene Counsel’s Living Lab Report, a digital tool designed to improve understanding of genetic test results and next steps, including CRM guidelines; or C) a control arm in which participants continue receiving standard care. Follow-up surveys will be conducted at 1, 3, and 12 months following randomization. These surveys include single-item measures, scales, and indices related to: 1) FC and CRM behaviors and behavioral factors following the COM-B theoretical framework (i.e., capability, opportunity, and motivation); 2) implementation outcomes (i.e., acceptability, appropriateness, exposure, and reach); and 3) other contextual factors (i.e., sociodemographic and clinical factors, and uncertainty, distress, and positive aspects of genetic test results). The primary outcomes are an increase in FC of genetic test results (Arm A) and improved engagement with guideline-based CRM without overtreatment or undertreatment (Arm B) by the 12-month follow-up survey. Discussion Our interventions are designed to shift the paradigm by which individuals with P/LP variants in inherited cancer genes are provided with information to enhance FC of genetic test results and engagement with guideline-based CRM. The information gathered through evaluating the effectiveness and implementation of these real-world approaches is needed to modify and scale up adaptive, stepped interventions that have the potential to maximize FC and CRM. Trial registration This study is registered at Clinicaltrials.gov (NCT04763915, date registered: February 21, 2021). Protocol version September 17th, 2021 Amendment Number 04.

Considerations in Management for Trans and Gender Diverse Patients with Inherited Cancer Risk

Purpose of Review To best support all patients with inherited cancer risk, we must broaden our scope of practice to consider the needs of the transgender and gender diverse (trans) community. We considered best practice for supporting trans patients including tailored risk assessments and management recommendations. Recent Findings There is limited literature considering trans patient care in cancer genetics. Small case studies have highlighted how medical transition and cancer risk–reducing options intersect with the need for individualised care. Studies have also shown that cancer genetics professionals do not feel prepared to support trans patients. Summary Patient-centred care for trans patients relies on a multidisciplinary team (MDT) engaged in shared decision-making. National guidelines are needed to standardise access to appropriate discussions around risk-reducing options and screening. International collaborative research is required to provide empiric data on the impact of gender-affirming treatments on cancer risk, and more experiential data is needed from trans patients accessing cancer genetics services. Finally, education and training in this area should be formally embedded for all cancer genetics professionals.

Histological and Somatic Mutational Profiles of Mismatch Repair Deficient Endometrial Tumours of Different Aetiologies

Background: Mismatch repair deficient (MMRd) tumours may arise from somatic events acquired during carcinogenesis or in the context of Lynch syndrome (LS), an inherited cancer predisposition condition caused by germline MMR pathogenic variants. Our aim was to explore whether sporadic and hereditary MMRd endometrial cancers (EC) display distinctive tumour biology. Methods: Clinically annotated LS-EC were collected. Histological slide review was performed centrally by two specialist gynaecological pathologists. Mutational analysis was by a bespoke 75- gene next-generation sequencing panel. Comparisons were made with sporadic MMRd EC. Multiple correspondence analysis was used to explore similarities and differences between the cohorts. Results: After exclusions, 135 LS-EC underwent independent histological review, and 64 underwent mutational analysis. Comparisons were made with 59 sporadic MMRd EC. Most tumours were of endometrioid histological subtype (92% LS-EC and 100% sporadic MMRd EC, respectively, p = NS). Sporadic MMRd tumours had significantly fewer tumour infiltrating lymphocytes (p ≤ 0.0001) and showed more squamous/mucinous differentiation than LS-EC (p = 0.04/p = 0.05). PTEN mutations were found in 88% sporadic MMRd and 61% LS-EC, respectively (p < 0.001). Sporadic MMRd tumours had significantly more mutations in PDGFRA, ALK, IDH1, CARD11, CIC, MED12, CCND1, PTPN11, RB1 and KRAS, while LS-EC showed more mutations affecting SMAD4 and ARAF. LS-EC showed a propensity for TGF-β signalling disruption. Cluster analysis found that wild type PTEN associates predominantly with LS-EC, whilst co-occurring mutations in PTEN, PIK3CA and KRAS predict sporadic MMRd EC. Conclusions: Whilst MMRd EC of hereditary and sporadic aetiology may be difficult to distinguish by histology alone, differences in infiltrating immune cell counts and mutational profile may predict heterogenous responses to novel targeted therapies and warrant further study.

649Personal history of keratinocyte carcinoma is a marker of inherited cancer risk: Mendelian randomization analyses

Background A personal history of keratinocyte carcinoma (KC) has been reported as a risk factor for developing subsequent primary cutaneous and non-cutaneous malignancies. However most evidence to date stems from observational studies which are prone to bias, confounding and reverse causation. Our aim was to examine this association using different Mendelian randomization (MR) approaches. Methods We performed a one-sample MR analysis using individual-level data from the UK Biobank (n = 394,306). This analysis was then validated in an independent dataset in the QSkin cohort (n = 16,896). Using 64 independent genetic variants known to be associated with KC, we generated a polygenic risk score (PRS) for each participant in the UK Biobank and the QSkin cohort. We then performed two-sample MR analyses using genome-wide association study (GWAS) summary statistics. We tested the association between genetically predicted KC and risk of subsequent cancer using logistic regression. Results Results from one-sample MR analyses in the UK Biobank indicated that a personal history of KC was significantly associated with cancer overall (excluding melanoma) (OR: 1.15, 95% CI: 1.10-1.20, per doubling the prevalence of KC). The results from the two-sample MR corroborate the findings from the one-sample MR, although the risk estimate was lower (OR: 1.05, 95% CI: 1.03-1.07). Conclusions Our MR analyses suggest that genetically predicted KC is a risk factor for developing subsequent primary malignancies. Key messages A personal history of KC may serve as a proxy marker of inherited cancer risk.