Longitudinal profiling identifies co-occurring BRCA1/2 reversions, TP53BP1, RIF1 and PAXIP1 mutations in PARP inhibitor-resistant advanced breast cancer

BACKGROUND

Resistance to therapies that target homologous recombination deficiency (HRD) in breast cancer limits their overall effectiveness. Multiple, preclinically validated, mechanisms of resistance have been proposed, but their existence and relative frequency in clinical disease are unclear, as is how to target resistance.

PATIENTS AND METHODS

Longitudinal mutation and methylation profiling of circulating tumour (ct)DNA was carried out in 47 patients with metastatic BRCA1-, BRCA2- or PALB2-mutant breast cancer treated with HRD-targeted therapy who developed progressive disease-18 patients had primary resistance and 29 exhibited response followed by resistance. ctDNA isolated at multiple time points in the patient treatment course (before, on-treatment and at progression) was sequenced using a novel >750-gene intron/exon targeted sequencing panel. Where available, matched tumour biopsies were whole exome and RNA sequenced and also used to assess nuclear RAD51.

RESULTS

BRCA1/2 reversion mutations were present in 60% of patients and were the most prevalent form of resistance. In 10 cases, reversions were detected in ctDNA before clinical progression. Two new reversion-based mechanisms were identified: (i) intragenic BRCA1/2 deletions with intronic breakpoints; and (ii) intragenic BRCA1/2 secondary mutations that formed novel splice acceptor sites, the latter being confirmed by in vitro minigene reporter assays. When seen before commencing subsequent treatment, reversions were associated with significantly shorter time to progression. Tumours with reversions retained HRD mutational signatures but had functional homologous recombination based on RAD51 status. Although less frequent than reversions, nonreversion mechanisms [loss-of-function (LoF) mutations in TP53BP1, RIF1 or PAXIP1] were evident in patients with acquired resistance and occasionally coexisted with reversions, challenging the notion that singular resistance mechanisms emerge in each patient.

CONCLUSIONS

These observations map the prevalence of candidate drivers of resistance across time in a clinical setting, information with implications for clinical management and trial design in HRD breast cancers.

Syndrome of inappropriate antidiuretic hormone secretion following bipolar transurethral resection of the prostate

Syndrome of inappropriate antidiuretic hormone secretion following minimally invasive surgery is extremely rare, having only been reported in a handful of cases. We present the second documented case of syndrome of inappropriate antidiuretic hormone secretion following transurethral resection in an 80-year-old male undergoing bipolar transurethral resection of the prostate for bladder outflow obstruction.

Level of evidence: 5

BOXIT-A Randomised Phase III Placebo-controlled Trial Evaluating the Addition of Celecoxib to Standard Treatment of Transitional Cell Carcinoma of the Bladder (CRUK/07/004)

BACKGROUND

Non-muscle-invasive bladder cancer (NMIBC) has a significant risk of recurrence despite adjuvant intravesical therapy.

OBJECTIVE

To determine whether celecoxib, a cyclo-oxygenase 2 inhibitor, reduces the risk of recurrence in NMIBC patients receiving standard treatment.

DESIGN, SETTING, AND PARTICIPANTS

BOXIT (CRUK/07/004, ISRCTN84681538) is a double-blinded, phase III, randomised controlled trial. Patients aged ≥18 yr with intermediate- or high-risk NMIBC were accrued across 51 UK centres between 1 November 2007 and 23 July 2012.

INTERVENTION

Patients were randomised (1:1) to celecoxib 200mg twice daily or placebo for 2 yr. Patients with intermediate-risk NMIBC were recommended to receive six weekly mitomycin C instillations; high-risk NMIBC cases received six weekly bacillus Calmette-Guérin and maintenance therapy.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The primary endpoint was time to disease recurrence. Analysis was by intention to treat.

RESULTS AND LIMITATIONS

A total of 472 patients were randomised (236:236). With median follow-up of 44 mo (interquartile range: 36-57), 3-yr recurrence-free rate (95% confidence interval) was as follows: celecoxib 68% (61-74%) versus placebo 64% (57-70%; hazard ratio [HR] 0.82 [0.60-1.12], p=0.2). There was no difference in high-risk (HR 0.77 [0.52-1.15], p=0.2) or intermediate-risk (HR 0.90 [0.55-1.48], p=0.7) NMIBC. Subgroup analysis suggested that time to recurrence was longer in pT1 NMIBC patients treated with celecoxib compared with those receiving placebo (HR 0.53 [0.30-0.94], interaction test p=0.04). The 3-yr progression rates in high-risk patients were low: 10% (6.5-17%) and 9.7% (6.0-15%) in celecoxib and placebo arms, respectively. Incidence of serious cardiovascular events was higher in celecoxib (5.2%) than in placebo (1.7%) group (difference +3.4% [-0.3% to 7.2%], p=0.07).

CONCLUSIONS

BOXIT did not show that celecoxib reduces the risk of recurrence in intermediate- or high-risk NMIBC, although celecoxib was associated with delayed time to recurrence in pT1 NMIBC patients. The increased risk of cardiovascular events does not support the use of celecoxib.

PATIENT SUMMARY

Celecoxib was not shown to reduce the risk of recurrence in intermediate- or high-risk non-muscle-invasive bladder cancer (NMIBC), although celecoxib was associated with delayed time to recurrence in pT1 NMIBC patients. The increased risk of cardiovascular events does not support the use of celecoxib.

The future of financing for HIV services in Uganda and the wider sub-Saharan Africa region: should we ask patients to contribute to the cost of their care?

Whilst multi-lateral funding for HIV/AIDS dramatically increased from 2004 to 2008, it has largely plateaued in the last 8 years. Across sub-Saharan Africa, up to 20 % of total spending on health is used for HIV services, and of this over 85 % is estimated to come from international funding rather than in-country sources. In Uganda, the fiscal liability to maintain services for all those who are currently receiving it is estimated to be as much as 3 % of Gross Domestic Product (GDP). In order to meet the growing need of increased patient numbers and further ART coverage the projected costs of comprehensive HIV care and treatment services will increase substantially. Current access to HIV care includes free at point of delivery (provided by Ministry of Health clinics), as well as out-of-pocket financing and health insurance provided care at private for- and not for- profit facilities. The HIV response is funded through Ugandan Ministry of Health national budget allocations, as well as multilateral donations such as the President's Emergency Plan for AIDS in Africa (PEPFAR) and Global Fund (GF) and other international funders. We are concerned that current funding mechanism for HIV programs in Uganda may be difficult to sustain and as service providers we are keen to explore ways in which provide lifelong HIV care to as many people living with HIV (PLHIV) as possible. Until such time as the Ugandan economy can support universal, state-supported, comprehensive healthcare, bridging alternatives must be considered. We suggest that offering patients with the sufficient means to assume some of the financial burden for their care in return for more convenient services could be one component of increasing coverage and sustaining services for those living with HIV.

The changes in prostate cancer and its management in the North West of England over a 10-year period

Objectives:

Our aim was to evaluate changes in prostate cancer diagnosis and management and to examine changes in the stage and grade of newly diagnosed prostate cancer in the North West of England over a 10-year period.

Materials and methods:

Data was collected concerning the diagnosis (including stage and grade) and management of newly diagnosed prostate cancer in the North West of England. There were three time points: 2003, 2007 and 2011 including a total of 648 patients. For assessment of median time changes Spearman’s Rank correlation test was used, for the assessment of changes in Gleason grade and clinical stage Mann–Whitney U test was used, and assessment of positive margin rates was done with Fisher’s test.

Results:

Median time from management decision to surgery has reduced from 46 (2003), 34 (2007) to 27 days (2011) ( p=0.074). The proportion of patients managed with active surveillance has remained relatively constant over time (18%, 16% and 21% respectively). More minimally invasive, nerve-sparing prostatectomies are now performed, and positive margin rates have significantly reduced from 53% (2003) to 23% (2011) ( p<0.001). Gleason grade significantly increased over time ( p<0.001); Gleason 7 disease was diagnosed in 23% of patients in 2003, 32% in 2007 and 49% in 2011 ( p<0.001). There was an increase in Gleason 8 disease; 6% (2003) to 8.6% (2011), but this was not significant ( p=0.27). Increase in clinical stage was also noted over time; identification of T3 disease rose from 2% (2003 and 2007) to 5% (2011) ( p=0.045) (excluding cases with non-recorded stage).

Conclusion:

Prostate cancer management in the North West of England has evolved over the last decade, with overall improvements in management quality. We have demonstrated an increase in the presenting stage and grade of prostate cancer over a 10-year period.

A rare case of testicular metastasis of bladder transitional cell carcinoma

Metastases from bladder transitional cell carcinoma (TCC) to the testis are very rare. These are usually found on autopsy and occur in advanced or metastatic bladder cancers. More common, known primary tumors that metastasize to the testis include prostate, lungs, melanoma, gastro-intestinal tract and the kidney. We report a rare case of solitary and synchronous metastatic TCC of the bladder to the testis, discovered on histological examination. This case illustrates that metastatic neoplasm to uncommon sites should be considered in the differential diagnosis for patients with a history of advanced bladder TCC.

Acute urinary retention in women due to urethral calculi: A rare case

We present a case of a 51-year-old woman with acute urinary retention caused by a urethral calculus. Urethral calculi in women are extremely rare and are usually formed in association with underlying genitourinary pathology. In this case, however, no pathology was detected via thorough urological evaluation. We discuss the pathogenesis, clinical presentation and treatment of urethral calculi. To our knowledge, this is the second reported case of a primary urethral calculus in a female with an anatomically normal urinary tract and the first in a middle-aged Caucasian female.

Abstract S4-02: Integrated genomic analyses of members of protein kinase C family identifies subtype specific alterations as novel therapeutic targets

Introduction

Members of the protein kinase C family are serine/threonine kinases that are involved in proliferation, apoptosis, cell survival and migration, and have been implicated in tumorigenesis. Recently PRKCE has been found to be up-regulated in triple-negative (TN) breast cancers and has been proposed as a target for therapeutic intervention. The aims of this study were to determine i) whether different members of the PKC family are dysregulated and/ or mutated in specific subtypes of breast cancer, ii) to investigate the impact of silencing or overexpression of members of the PKC family in cell line models representative of the different breast cancer subtypes.

Material and methods:

We obtained expression and mutational data from the cancer genome atlas (TCGA) project from 567 and 640 samples subjected to microarray-based gene expression profiling and whole exome sequencing, respectively. Pair-wise SAM analysis of TCGA gene expression data was performed to identify differential expression between subgroups (ER+, HER2+ and TN). Potential driver mutations were identified through the algorithm CHASM. Subtype specific dependencies were identified from the re-analysis of publicly available siRNA kinome-wide screens in a panel of 20 breast cancer cell lines. In vitro assessment of gene overexpression was assessed in MCF10A cells by wound healing scratch assays and 3D growth in Matrigel.

Results

PRKCA, B, I and Q were expressed at significantly higher levels in TN breast cancers. Higher expression of PRKCE was significantly associated with ER-negativity, whereas high PRKCD expression was associated with ER-positivity. Analysis of siRNA kinome-wide screen data resulted in a significant reduction in survival associated with PRKCI and PRKCE in ER-negative cells, PRKCQ in triple-negative cells, and PRKCD in ER-positive cells. Furthermore meta-analysis of published exome and whole genome sequencing data identified potentially activating recurrent kinase domain mutations in PRKCB (0.93%), Q (1.25%) and Z (0.93%), with mutations in PRKCZ being associated with higher gene expression. Forced expression of wild-type PRKCQ and PRKCZ in MCF10A cells resulted in the formation of irregular acini in 3D cell culture and expression of wild-type PRKCZ resulted in increased migration.

Conclusions

Differential expression of members of the protein kinase C family, are associated with different molecular subtypes of breast cancer. Furthermore, we have shown that breast cancer cells are dependent upon expression of these family members in vitro, which are associated with different cellular phenotypes.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr S4-02.

Diethylstilboestrol for the treatment of prostate cancer: past, present and future

The aim of this review was to discuss the most recent data from current trials of diethylstilboestrol (DES) to identify its present role in advanced prostate cancer treatment as new hormonal therapies emerge. The most relevant clinical studies using DES in castration-refractory prostate cancer (CRPC) were identified from the literature. The safety, efficacy, outcomes and mechanisms of action are summarized. In the age of chemotherapy this review highlights the efficacy of oestrogen therapy in CRPC. The optimal point in the therapeutic pathway at which DES should be prescribed remains to be established.

Bladder neck sparing in radical prostatectomy

The role of a bladder neck sparing (BNS) technique in radical prostatectomy (RP) remains controversial. The potential advantages of improved functional recovery must be weighed against oncological outcomes. We performed a literature review to evaluate the current knowledge regarding oncological and functional outcomes of BNS and bladder neck reconstruction (BNr) in RP. A systematic literature review using on-line medical databases was performed. A total of 33 papers were identified evaluating the use of BNS in open, laparoscopic and robotic-assisted RP. The majority were retrospective case series, with only one prospective, randomised, blinded study identified. The majority of papers reported no significant difference in oncological outcomes using a BNS or BNr technique, regardless of the surgical technique employed. Quoted positive surgical margin rates ranged from 6% to 32%. Early urinary continence (UC) rates were ranged from 36% to 100% at 1 month, with long-term UC rate reported at 84-100% at 12 months if the bladder neck (BN) was spared. BNS has been shown to improve early return of UC and long-term UC without compromising oncological outcomes. Anastomotic stricture rate is also lower when using a BNS technique.

Integrative molecular and functional profiling of ERBB2-amplified breast cancers identifies new genetic dependencies

Overexpression of the receptor tyrosine kinase ERBB2 (also known as HER2) occurs in around 15% of breast cancers and is driven by amplification of the ERBB2 gene. ERBB2 amplification is a marker of poor prognosis, and although anti-ERBB2-targeted therapies have shown significant clinical benefit, de novo and acquired resistance remains an important problem. Genomic profiling has demonstrated that ERBB2+ve breast cancers are distinguished from ER+ve and 'triple-negative' breast cancers by harbouring not only the ERBB2 amplification on 17q12, but also a number of co-amplified genes on 17q12 and amplification events on other chromosomes. Some of these genes may have important roles in influencing clinical outcome, and could represent genetic dependencies in ERBB2+ve cancers and therefore potential therapeutic targets. Here, we describe an integrated genomic, gene expression and functional analysis to determine whether the genes present within amplicons are critical for the survival of ERBB2+ve breast tumour cells. We show that only a fraction of the ERBB2-amplified breast tumour lines are truly addicted to the ERBB2 oncogene at the mRNA level and display a heterogeneous set of additional genetic dependencies. These include an addiction to the transcription factor gene TFAP2C when it is amplified and overexpressed, suggesting that TFAP2C represents a genetic dependency in some ERBB2+ve breast cancer cells.

Establishment and characterisation of a new breast cancer xenograft obtained from a woman carrying a germline BRCA2 mutation

Background:

The BRCA2 gene is responsible for a high number of hereditary breast and ovarian cancers, and studies of the BRCA2 biological functions are limited by the lack of models that resemble the patient's tumour features. The aim of this study was to establish and characterise a new human breast carcinoma xenograft obtained from a woman carrying a germline BRCA2 mutation.

Methods:

A transplantable xenograft was obtained by grafting a breast cancer sample into nude mice. The biological and genetic profiles of the xenograft were compared with that of the patient's tumour using histology, immunohistochemistry (IHC), BRCA2 sequencing, comparative genomic hybridisation (CGH), and qRT–PCR. Tumour response to standard chemotherapies was evaluated.

Results:

Histological profile identified the tumour as a basal-like triple-negative breast cancer. Targeted BRCA2 DNA sequencing of the xenograft showed the presence of the mutation previously identified in the carrier. Comparative genomic hybridisation array profiles of the primary tumour and the xenograft revealed a high number of similar genetic alterations. The therapeutic assessment of the xenograft showed sensitivity to anthracyclin-based chemotherapy and resistance to docetaxel. The xenograft was also highly sensitive to radiotherapy and cisplatin-based treatments.

Conclusions:

This study describes a new human breast cancer xenograft obtained from a BRCA2-mutated patient. This xenograft provides a new model for the pre-clinical drug development and for the exploration of the drug response biological basis.

Iatrogenic iodine as a cause of hypothyroidism in infants with end-stage renal failure

Between 1996 and 2005, two of seven infants in our unit on overnight continuous-cycle peritoneal dialysis (CCPD) acquired hypothyroidism following normal thyroid function on neonatal screening. Case 1 had posterior urethral valves, commenced CCPD at day 29, and developed hypothyroidism requiring treatment at 3 months: TSH 258 micro/l (ref.: 0.3-3.8), total thyroxine 74 nmol/l (ref.: 77-159). Plasma iodine concentration was 7.44 micromol/l (ref.: 0.23-0.68). Iodine concentrations in peritoneal dialysis (PD) fluid were found to be higher at the end of the first cycle (11.4 micromol/l) than at the end of the twelfth cycle (1.55 micromol/l). Case 2 had posterior urethral valves, commenced CCPD on day 4 and was diagnosed with hypothyroidism following a prolonged jaundice screen. Thyroxine replacement was stopped 2 months after a renal transplant. A third child commenced CCPD on day 2 and had high plasma iodine concentrations at 8 weeks (5.79 micromol/l). He had borderline thyroid function, not requiring replacement. Our hypothesis is that these infants developed hypothyroidism as a consequence of iodine exposure via the Wolff-Chaikoff effect. Iodine levels were higher in the PD fluid than in plasma. This suggests that povidine-iodine 10% in the PD cap may be the source of the high plasma iodine levels.

Systemic capacity building: a hierarchy of needs

'Capacity building' is the objective of many development programmes and a component of most others. However, satisfactory definitions continue to elude us, and it is widely suspected of being too broad a concept to be useful. Too often it becomes merely a euphemism referring to little more than training. This paper argues that it is more important to address systemic capacity building, identifying a pyramid of nine separate but interdependent components. These form a four-tier hierarchy of capacity building needs: (1) structures, systems and roles, (2) staff and facilities, (3) skills, and (4) tools. Emphasizing systemic capacity building would improve diagnosis of sectoral shortcomings in specific locations, improve project/programme design and monitoring, and lead to more effective use of resources. Based on extensive action research in 25 States, experience from India is presented to illustrate how the concept of the capacity building pyramid has been put to practical use.