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Background: While protein truncating variants in RAD51C have been shown to predispose to triple negative breast cancer (TNBC) and ovarian cancer, little is known about the pathogenicity of missense (MS) variants. Methods: The frequency of rare RAD51C MS variants were assessed in the BEACCON study of 5,734 familial breast cancer cases and 14,382 population controls, and integrated with tumour sequencing data from 21 cases carrying a candidate variant to assess bi-allelic inactivation. Results: Collectively, a significant enrichment of rare missense variants was detected in cases (MAF < 0.001, OR 1.57, 95%CI 1.00 - 2.44, p = 0.05), particularly for variants with a REVEL score > 0.5 (OR 3.95, 95%CI 1.40 - 12.01, p = 0.006). Despite the large sample size, the majority of variants detected were very rare, precluding definitive conclusions about pathogenicity based solely on the case-control data. Sequencing of 21 tumours from carriers of one of eight candidate MS variants, identified four cases with bi-allelic inactivation through loss of the wild-type allele, while six lost the variant allele and ten remained heterozygous. Loss of the wild-type alleles corresponded strongly with ER- and triple-negative breast tumours and a high homologous recombination deficiency score. Conclusions: Using this approach, the p.Gly264Ser variant, which was previously suspected to be pathogenic based on small case-control analyses and loss of activity in in vitro functional assays, was shown to be benign with similar prevalence in cases and controls, and eight out of nine tumours showing loss of the variant allele or retention of heterozygosity. Conversely, the combined case-control and tumour sequencing data identified p.Ile144Thr, p.Arg212His, p.Gln143Arg and p.Gly114Arg as variants warranting further investigation.

Preclinical testing is a crucial step in evaluating cancer therapeutics. We aimed to establish a significant resource of patient-derived xenografts (PDXs) of prostate cancer for rapid and systematic evaluation of candidate therapies. The PDX collection comprises 59 tumors collected from 30 patients between 2012–2020, coinciding with availability of abiraterone and enzalutamide. The PDXs represent the clinico-pathological and genomic spectrum of prostate cancer, from treatment-naïve primary tumors to castration-resistant metastases. Inter- and intra-tumor heterogeneity in adenocarcinoma and neuroendocrine phenotypes is evident from bulk and single-cell RNA sequencing data. Organoids can be cultured from PDXs, providing further capabilities for preclinical studies. Using a 1 x 1 x 1 design, we rapidly identify tumors with exceptional responses to combination treatments. To govern the distribution of PDXs, we formed the Melbourne Urological Research Alliance (MURAL). This PDX collection is a substantial resource, expanding the capacity to test and prioritize effective treatments for prospective clinical trials in prostate cancer., The prognosis of castration-resistant prostate cancers remains dismal, but accurate preclinical models can lead to effective therapies. Here the Melbourne Urological Research Alliance establish prostate cancer patient-derived xenografts, use the tumors for organoids and single-cell RNA-seq, and show the efficacy of PARP inhibitor combination treatments.

Various forms of private investment are considered necessary for the sustainability of biobanks, yet pose significant challenges to public trust. To manage this tension, it is vital to identify the concerns of relevant stakeholders to ensure effective and acceptable policy and practice. This research examines the aspects of commercialisation that are of most concern to the Australian public (n = 800) and patients who had donated their tissue to two large disease specific (cancer) public biobanks (n = 564). Overall, we found a commercialisation effect (higher support for public relative to private) in relation to funding, research location and access to stored biospecimens. The effect was strongest for research locations and access compared to funding. A latent class analysis revealed the pattern of concern differed, with the majority (34.1%) opposing all aspects of commercialisation, a minority supporting all (15.7%), one quarter (26.8%) opposing some (sharing and selling tissue) but not others (research locations and funding), and a group who were unsure about most aspects but opposed selling tissue (23.5%). Patient donors were found to be more accepting of and unsure about most aspects of commercialisation. Members of the (general) public who were motivated to participate in biobanking were more likely to oppose some aspects while supporting others, while those who indicated they would not donate to a biobank were more likely to oppose all aspects of commercialisation. The results suggest that approaches to policy, engagement and awareness raising need to be tailored for different publics and patient groups to increase participation.

Background Research identifying and returning clinically actionable germline variants offer a new avenue of access to genetic information. The psychosocial and clinical outcomes for women who have received this ‘genome-first care’ delivering hereditary breast and ovarian cancer risk information outside of clinical genetics services are unknown. Methods: An exploratory sequential mixed-methods case-control study compared outcomes between women who did (cases; group 1) and did not (controls; group 2) receive clinically actionable genetic information from a research cohort in Victoria, Australia. Participants completed an online survey examining cancer risk perception and worry, and group 1 also completed distress and adaptation measures. Group 1 participants subsequently completed a semi structured interview. Results: Forty-five participants (group 1) and 96 (group 2) completed the online survey, and 31 group 1 participants were interviewed. There were no demographic differences between groups 1 and 2, although more of group 1 participants had children (p = 0.03). Group 1 reported significantly higher breast cancer risk perception (p < 0.001) compared to group 2, and higher cancer worry than group 2 (p < 0.001). Some group 1 participants described how receiving their genetic information heightened their cancer risk perception and exacerbated their cancer worry while waiting for risk-reducing surgery. Group 1 participants reported a MICRA mean score of 27.4 (SD 11.8, range 9–56; possible range 0–95), and an adaptation score of 2.9 (SD = 1.1). Conclusion: There were no adverse psychological outcomes amongst women who received clinically actionable germline information through a model of ‘genome-first’ care compared to those who did not. These findings support the return of clinically actionable research results to research participants.

Personal Breast Cancer (BC) Risk Assessments (PBCRA) have potential to stratify women into clinically-actionable BC risk categories. As this could involve population-wide genomic testing, women’s attitudes to PBCRA and views on acceptable implementation platforms must be considered to ensure optimal population participation. We explored these issues with 31 women with different BC risk profiles through semi-structured focus group discussions or interviews. Inductive thematic coding of transcripts was performed. Subsequently, women listed factors that would impact on their decision to participate. Participants’ attitudes to PBCRA were positive. Identified themes included that PBCRA acceptance hinges on result actionability. Women value the ability to inform decision-making. Participants reported anxiety, stress, and genetic discrimination as potential barriers. The age at which PBCRA was offered, ease of access, and how results are returned held importance. Most women value the opportunity for PBCRA to inform increased surveillance, while highlighting hesitance to accept reduced surveillance as they find reassurance in regular screening. Women with BRCA pathogenic variants value the potential for PBCRA to identify a lower cancer risk and potentially inform delayed prophylactic surgery. This study highlights complexities in adopting advances in BC early detection, especially for current users who value existing processes as a social good.

Breast cancer (BC) diagnosed after a negative mammogram but prior to the next screening episode is termed an 'interval BC' (IBC). Understanding the molecular differences between IBC and screen-detected BCs (SDBC) could improve mammographic screening and management options. Therefore, we assessed both germline and somatic genomic aberrations in a prospective cohort. Utilising the Lifepool cohort of >54 000 women attending mammographic screening programs, 930 BC cases with screening status were identified (726 SDBC and 204 IBC). Clinico-pathological and family history information were recorded. Germline and tumour DNA were collected where available and sequenced for BC predisposition and driver gene mutations. Compared to SDBC, IBCs were significantly associated with a younger age at diagnosis and tumour characteristics associated with worse prognosis. Germline DNA assessment of BC cases that developed post-enrolment (276 SDBCs and 77 IBCs) for pathogenic mutations in 12 hereditary BC predisposition genes identified 8 carriers (2.27%). The germline mutation frequency was higher in IBC versus SDBC, although not statistically significant (3.90% versus 1.81%, p = 0.174). Comparing somatic genetic features of IBC and SDBC matched for grade, histological subtype and hormone receptor revealed no significant differences, with the exception of higher homologous recombination deficiency scores in IBC, and copy number changes on chromosome Xq in triple negative SDBCs. Our data demonstrates that while IBCs are clinically more aggressive than SDBC, when matched for confounding clinico-pathological features they do not represent a unique molecular class of invasive BC, but could be a consequence of timing of tumour initiation and mammographic screening. Copyright © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Mixed Lineage Kinase 2 is a mammalian protein kinase that activates stress-activated protein kinases/c-jun N-terminal kinases (SAPK/JNKs) through direct phosphorylation of their upstream activator, SEK1/JNKK. We have examined expression of both MLK2 and SEK1/JNKK RNAs in the rat testis at various times during postnatal development and in isolated testicular cell populations. We also have used immunohistochemistry to examine MLK2 protein expression and localization in adult rat and mouse testis. In these analyses, we found rat MLK2 mRNA expression was first evident at a very low level on day 25 after birth and present from day 35 at much higher levels that continue into adulthood. In RNA from isolated cell types, a MLK2 transcript was detected in primary spermatocytes and round spermatids, but not in Leydig or Sertoli cells. MLK2 RNA was also absent from the testis of rats after induced cryptorchidism. SEK1/JNKK transcripts, on the other hand, were present at all stages of testicular development and in all cell types tested. In tissue sections from both adult rat and mouse testis, MLK2 immunoreactivity was present in the nucleus of primary and secondary spermatocytes and round spermatids within seminiferous tubules, but was absent from spermatogonia. These findings indicate the JNK pathway is most likely ubiquitous in rodent testicular cells, while the cell-specific pattern of MLK2 expression suggests that it may be involved in the regulation of processes specific to post-mitotic germ cells. Furthermore, the finding of MLK2 protein in the nucleus of spermatocytes and round spermatids indicates a role for MLK2 in regulation of nuclear events specific to germ cell development.

Using the polymerase chain reaction to study mRNA expressed in human epithelial tumor cells, a member of a new family of protein kinases was identified. The catalytic domain of this kinase has amino-acid-sequence similarity to both the Tyr-specific and the Ser/Thr-specific kinase classes. Clones representing two members of this new family have been isolated from a human colonic epithelial cDNA library and sequenced. The predicted amino-acid sequences of these clones reveal that, in addition to the unusual nature of their kinase catalytic domains, they contain two Leu/Ile-zipper motifs and a basic sequence, near their C-termini. As they possess domains associated with proteins from two distinct functional groups, these kinases have been named mixed-lineage kinases (MLK) 1 and 2. mRNA from MLK1 has been found to be expressed in epithelial tumor cell lines of colonic, breast and esophageal origin. The MLK1 gene has been mapped to human chromosome 14q24.3-31.

10537 Background: Genomic alterations are likely to precede the phenotypic changes of breast cancer (BC) and include hyper- methylation of tumour suppressor genes. An intraductal approach, such as ductal lavage (DL), is an attractive means of accessing ductal epithelial and other cells in a prospective fashion. Methods: Women with at least one breast unaffected by BC, with a germline BRCA1 or BRCA2 mutation, attended for 6-monthly DL collection for up to 3 years. Standard methods were used for DNA extraction and bisulfite conversion. Hyper-methylation of p16, RASSF1A, twist and RARβ genes was investigated using a qualitative, real-time, nested PCR assay. Associations between methylation status and categorical variables were tested using Fisher's exact test including cytological findings and BC incidence. Logistic regression was used to examine the relationship between methylation status and patient age, and to examine the effects of multiple variables. Analyses were performed at three levels; samples from a single breast over time and from a single duct over time and each sample in isolation. Results: A total of 173 DL samples from 98 ducts in 56 breasts were analysed in 34 women (16 BRCA1 and 18 BRCA2 mutation carriers) with a median age of 43 years (range 27- 60). DL fluid was collected from all women on at least one occasion (median 2.5 visits, range 1–5). Five women developed BC on study. Methylation of p16 was strongly associated with a known BRCA1 mutation (p=0.0003, p No significant financial relationships to disclose.