PAM trial protocol: a randomised feasibility study of psychedelic microdosing-assisted meaning-centred psychotherapy in advanced stage cancer patients.

BACKGROUND: An advanced cancer diagnosis can be associated with a significant profile of distress. Psychedelic compounds have shown clinically significant effects in the treatment of psychological distress in patients with advanced-stage cancer. Given the challenges of delivering timely and effective intervention in the advanced cancer context, it is possible that an alternative, more pragmatic, approach lies in psychedelic 'microdosing'. Microdosing refers to repeated administration of psychedelics in sub-hallucinogenic doses. The purpose of this study is to evaluate the feasibility of conducting a full-scale randomised controlled trial comparing psychedelic microdose-assisted-meaning-centred psychotherapy (PA-MCP) to standard meaning-centred psychotherapy (MCP) in New Zealand indigenous (Maori) and non-indigenous people with advanced cancer and symptoms of anxiety and/or depression. Although MCP is a well-established psychotherapeutic treatment in advanced cancer populations, the potential efficacy and effectiveness of this therapy when delivered alongside a standardised microdose regimen of a psychedelic compound have not been investigated. METHODS: Participants with advanced-stage cancer and symptoms of anxiety and/or depression (N = 40; 20 Maori, 20 non-Maori) will be randomised under double-blind conditions to receive 7 sessions of MCP alongside 13 doses of either an LSD microdose (4-20 µg) (PA-MCP) or inactive placebo (placebo-MCP). The feasibility, acceptability, and safety of this intervention and physiological and psychological measures will be recorded at baseline, at each session of MCP, and at a 1-month and 6-month follow-up. DISCUSSION: Our findings will evaluate the feasibility, acceptability, and safety of a larger randomised controlled trial and provide an initial indication of the potential benefits of psychedelic microdosing for psychological distress in advanced-stage indigenous and non-indigenous cancer patients. TRIAL REGISTRATION: NZCTR, ACTRN12623000478617. Registered 11 May 2023.  https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=385810&isReview=true .

Testosterone suppression plus enzalutamide versus testosterone suppression plus standard antiandrogen therapy for metastatic hormone-sensitive prostate cancer (ENZAMET): an international, open-label, randomised, phase 3 trial.

BACKGROUND: The interim analysis of the ENZAMET trial of testosterone suppression plus either enzalutamide or standard nonsteroidal antiandrogen therapy showed an early overall survival benefit with enzalutamide. Here, we report the planned primary overall survival analysis, with the aim of defining the benefit of enzalutamide treatment in different prognostic subgroups (synchronous and metachronous high-volume or low-volume disease) and in those who received concurrent docetaxel. METHODS: ENZAMET is an international, open-label, randomised, phase 3 trial conducted at 83 sites (including clinics, hospitals, and university centres) in Australia, Canada, Ireland, New Zealand, the UK, and the USA. Eligible participants were males aged 18 years or older with metastatic, hormone-sensitive prostate adenocarcinoma evident on CT or bone scanning with 99mTc and an Eastern Cooperative Oncology Group performance status score of 0-2. Participants were randomly assigned (1:1), using a centralised web-based system and stratified by volume of disease, planned use of concurrent docetaxel and bone antiresorptive therapy, comorbidities, and study site, to receive testosterone suppression plus oral enzalutamide (160 mg once per day) or a weaker standard oral non-steroidal antiandrogen (bicalutamide, nilutamide, or flutamide; control group) until clinical disease progression or prohibitive toxicity. Testosterone suppression was allowed up to 12 weeks before randomisation and for up to 24 months as adjuvant therapy. Concurrent docetaxel (75 mg/m2 intravenously) was allowed for up to six cycles once every 3 weeks, at the discretion of participants and physicians. The primary endpoint was overall survival in the intention-to-treat population. This planned analysis was triggered by reaching 470 deaths. This study is registered with ClinicalTrials.gov, NCT02446405, ANZCTR, ACTRN12614000110684, and EudraCT, 2014-003190-42. FINDINGS: Between March 31, 2014, and March 24, 2017, 1125 participants were randomly assigned to receive non-steroidal antiandrogen (n=562; control group) or enzalutamide (n=563). The median age was 69 years (IQR 63-74). This analysis was triggered on Jan 19, 2022, and an updated survival status identified a total of 476 (42%) deaths. After a median follow-up of 68 months (IQR 67-69), the median overall survival was not reached (hazard ratio 0·70 [95% CI 0·58-0·84]; p<0·0001), with 5-year overall survival of 57% (0·53-0·61) in the control group and 67% (0·63-0·70) in the enzalutamide group. Overall survival benefits with enzalutamide were consistent across predefined prognostic subgroups and planned use of concurrent docetaxel. The most common grade 3-4 adverse events were febrile neutropenia associated with docetaxel use (33 [6%] of 558 in the control group vs 37 [6%] of 563 in the enzalutamide group), fatigue (four [1%] vs 33 [6%]), and hypertension (31 [6%] vs 59 [10%]). The incidence of grade 1-3 memory impairment was 25 (4%) versus 75 (13%). No deaths were attributed to study treatment. INTERPRETATION: The addition of enzalutamide to standard of care showed sustained improvement in overall survival for patients with metastatic hormone-sensitive prostate cancer and should be considered as a treatment option for eligible patients. FUNDING: Astellas Pharma.

Efficacy and Safety of Telaglenastat Plus Cabozantinib vs Placebo Plus Cabozantinib in Patients With Advanced Renal Cell Carcinoma: The CANTATA Randomized Clinical Trial.

Importance: Dysregulated metabolism is a hallmark of renal cell carcinoma (RCC). Glutaminase is a key enzyme that fuels tumor growth by converting glutamine to glutamate. Telaglenastat is an investigational, first-in-class, selective, oral glutaminase inhibitor that blocks glutamine utilization and downstream pathways. Preclinically, telaglenastat synergized with cabozantinib, a VEGFR2/MET/AXL inhibitor, in RCC models. Objective: To compare the efficacy and safety of telaglenastat plus cabozantinib (Tela + Cabo) vs placebo plus cabozantinib (Pbo + Cabo). Design, Setting, and Participants: CANTATA was a randomized, placebo-controlled, double-blind, pivotal trial conducted at sites in the US, Europe, Australia, and New Zealand. Eligible patients had metastatic clear-cell RCC following progression on 1 to 2 prior lines of therapy, including 1 or more antiangiogenic therapies or nivolumab plus ipilimumab. The data cutoff date was August 31, 2020. Data analysis was performed from December 2020 to February 2021. Interventions: Patients were randomized 1:1 to receive oral cabozantinib (60 mg daily) with either telaglenastat (800 mg twice daily) or placebo until disease progression or unacceptable toxicity. Main Outcomes and Measures: The primary end point was progression-free survival (Response Evaluation Criteria in Solid Tumors version 1.1) assessed by blinded independent radiology review. Results: A total of 444 patients were randomized: 221 to Tela + Cabo (median [range] age, 61 [21-81] years; 47 [21%] women and 174 [79%] men) and 223 to Pbo + Cabo (median [range] age, 62 [29-83] years; 68 [30%] women and 155 [70%] men). A total of 276 (62%) patients had received prior immune checkpoint inhibitors, including 128 with prior nivolumab plus ipilimumab, 93 of whom had not received prior antiangiogenic therapy. Median progression-free survival was 9.2 months for Tela + Cabo vs 9.3 months for Pbo + Cabo (HR, 0.94; 95% CI, 0.74-1.21; P = .65). Overall response rates were 31% (69 of 221) with Tela + Cabo vs 28% (62 of 223) with Pbo + Cabo. Treatment-emergent adverse event (TEAE) rates were similar between arms. Grade 3 to 4 TEAEs occurred in 160 patients (71%) with Tela + Cabo and 172 patients (79%) with Pbo + Cabo and included hypertension (38 patients [17%] vs 40 patients [18%]) and diarrhea (34 patients [15%] vs 29 patients [13%]). Cabozantinib was discontinued due to AEs in 23 patients (10%) receiving Tela + Cabo and 33 patients (15%) receiving Pbo + Cabo. Conclusions and Relevance: In this randomized clinical trial, telaglenastat did not improve the efficacy of cabozantinib in metastatic RCC. Tela + Cabo was well tolerated with AEs consistent with the known risks of both agents. Trial Registration: ClinicalTrials.gov Identifier: NCT03428217.

Health-Related Quality of Life in Metastatic, Hormone-Sensitive Prostate Cancer: ENZAMET (ANZUP 1304), an International, Randomized Phase III Trial Led by ANZUP.

PURPOSE: We previously reported that enzalutamide improved overall survival when added to standard of care in metastatic, hormone-sensitive prostate cancer. Here, we report its effects on aspects of health-related quality of life (HRQL). METHODS: HRQL was assessed with the European Organisation for Research and Treatment of Cancer core quality-of-life questionnaire and QLM-PR25 at weeks 0, 4, 12, and then every 12 weeks until progression. Scores from week 4 to 156 were analyzed with repeated measures modeling to calculate group means and differences. Deterioration-free survival was from random assignment until the earliest of death, clinical progression, discontinuation of study treatment, or a worsening of 10 points or more from baseline in fatigue, physical function, cognitive function, or overall health and quality of life (OHQL). HRQL scores range from 0 (lowest possible) to 100 (highest possible). RESULTS: HRQL was assessed in 1,042 of 1,125 participants (93%). Differences in means favored control over enzalutamide for fatigue (5.2, 95% CI, 3.6 to 6.9; P < .001), cognitive function (4.0, 95% CI, 2.5 to 5.5; P < .001), and physical function (2.6, 95% CI, 1.3 to 3.9; P < .001), but not OHQL (1.2, 95% CI, -0.2 to 2.7; P = .1). Deterioration-free survival rates at 3 years, and log-rank P values comparing the whole distributions, favored enzalutamide over control for OHQL (31% v 17%; P < .0001), cognitive function (31% v 20%; P = .001), and physical function (31% v 22%; P < .001), but not fatigue (24% v 18%; P = .16). The effects of enzalutamide on HRQL were independent of baseline characteristics. CONCLUSION: Enzalutamide was associated with worsening of self-reported fatigue, cognitive function, and physical function, but not OHQL. Enzalutamide was associated with improved deterioration-free survival for OHQL, physical function, and cognitive function because delays in disease progression outweighed early deteriorations in these aspects of HRQL.

Overall Survival of Men with Metachronous Metastatic Hormone-sensitive Prostate Cancer Treated with Enzalutamide and Androgen Deprivation Therapy.

Men who initially present with localized prostate cancer and later develop metachronous metastases have a better prognosis than men with de novo metastatic disease and often have a low burden of disease on conventional imaging. Some have disease amenable to metastasis-directed therapy for lymph node or bone metastases, a strategy used by some because no documented overall survival (OS) benefit of combination systemic therapy in this setting. We report data for patients prospectively classified as "M0" at initial diagnosis from the interim analysis of the ENZAMET trial, with 34 mo of median follow-up for survivors. A total of 312 (28%) of the 1125 enrolled patients were classified as M0 at diagnosis, and 205 (66%) of the 312 patients had low-volume disease at study entry as per the CHAARTED criteria. The hazard ratio for OS, that is, HR(OS), was 0.56 (95% confidence interval [CI]: 0.29-1.06) with the addition of enzalutamide for all patients with metachronous metastatic hormone-sensitive prostate cancer, and for the low-volume subset the HR(OS) was 0.40 (95% CI: 0.16-0.97). The 3-yr OS was 83% without and 89% with enzalutamide for all patients with metachronous metastases, and 83% and 92%, respectively, for the low-volume subset. Intensification of hormonal therapy should strongly be considered for these men. PATIENT SUMMARY: Many men present with prostate cancer that has spread to distant sites beyond the prostate gland years after their initial diagnosis and treatment, while others have distant spread at the time the cancer is diagnosed. On average, men whose cancer comes back years after the initial diagnosis often survive much longer than men whose cancer has been found to spread to distant sites when it is first diagnosed. In this report, we demonstrate strong evidence for the first time that the survival of men whose cancer comes back years later is improved when drugs such as enzalutamide or apalutamide are added to testosterone suppression in this setting.

Communicating prognostic information: what do oncologists think patients with incurable cancer should be told?

BACKGROUND: People with incurable cancer require information about their prognosis to make informed decisions about their future. AIMS: To determine the frequency, form and documentation of prognostic discussions between oncologists and their patients with incurable cancer. METHODS: We surveyed medical oncologists in Australia and New Zealand about their practices communicating prognosis. RESULTS: A total of 206 medical oncologists completed the survey. Respondent characteristics were: median age 40 years (range 27-75), female 51%, trainee 22%; and 71% had completed specific training on communicating prognosis. Respondents reported discussing prognosis with a patient a median of 10 times per month (interquartile range 4-15); 88% reported explaining that 'the cancer is incurable' to all their patients with incurable cancer and 84% reported always or usually providing a quantitative estimate of survival time. The preferred method for explaining expected survival time (EST) was providing 'multiple ranges of time with probabilities, for example best-case, typical and worst-case scenarios' (52% of respondents). The most frequently reported barriers to discussing EST were: 'family members requesting that prognostic information not be discussed' (57% of respondents), and 'not knowing the EST' (46% of respondents). Twenty percent reported always documenting prognostic discussions and the EST in the patient's medical record, and 11% reported always documenting this information in their letters to other doctors. CONCLUSIONS: Most oncologists reported providing quantitative estimates of EST to their patients with incurable cancer, but very few reported documenting this information. Methods to help oncologists estimate, explain and document survival time are needed to improve communication of prognosis.

TheraP: a randomized phase 2 trial of 177 Lu-PSMA-617 theranostic treatment vs cabazitaxel in progressive metastatic castration-resistant prostate cancer (Clinical Trial Protocol ANZUP 1603).

OBJECTIVE: To assess the activity and safety of cabazitaxel chemotherapy vs that of treatment with 177 Lu-PSMA-617, a novel radiolabelled small molecule that binds with high affinity to prostate-specific membrane antigen (PSMA), in men with metastatic castration-resistant prostate cancer (mCRPC) who have received prior docetaxel treatment. PATIENTS AND METHODS: The TheraP trial (ANZUP 1603) is an open-label, randomized, stratified, two-arm multicentre phase 2 trial comparing the activity and safety of cabazitaxel chemotherapy vs 177 Lu-PSMA-617 therapy in the treatment of men with mCRPC. Key eligibility criteria include prior docetaxel chemotherapy, rising prostate-specific antigen (PSA) level, sufficient PSMA avidity, as defined by centrally reviewed 68 Ga-PSMA-11 and fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) with no discordant FDG-avid PSMA-negative sites of disease. Patients in the control group receive standard treatment with cabazitaxel (20 mg/m2 ) i.v. every 3 weeks with prednisolone 10 mg daily orally, for a maximum of 10 cycles. Patients in the experimental group receive 177 Lu-PSMA-617 (8.5 GBq decreasing by 0.5 GBq per cycle) i.v. every 6 weeks, for up to a maximum of six cycles. In the event of an exceptional response as defined on centrally reviewed post-therapy single-photon emission CT imaging, treatment will be suspended but can recommence on progression. The trial aims to include 200 patients who will be centrally randomized to one of the two treatment groups, in a 1:1 ratio. The primary endpoint is PSA response. Secondary endpoints are overall survival, progression-free survival (PFS), radiographic PFS, PSA PFS, objective tumour response, pain response, pain PFS, health-related quality of life, and frequency and severity of adverse events. The treatment and outcomes of patients excluded on the basis of low PSMA avidity or discordant FDG-avid disease on screening 68 Ga-PSMA-11 and Fluorine-18 (18 F)-FDG-PET/CT scan will also be assessed. Enrolment in the study commenced on 29 January 2018. RESULTS AND CONCLUSIONS: 177 Lu-PSMA-617 offers a potential additional life-prolonging treatment option for men with mCRPC. The results of this trial will determine, for the first time in a randomized design, the activity and safety of 177 Lu-PSMA-617, as compared with cabazitaxel chemotherapy in men with progressive mCRPC.

Enzalutamide with Standard First-Line Therapy in Metastatic Prostate Cancer.

BACKGROUND: Enzalutamide, an androgen-receptor inhibitor, has been associated with improved overall survival in men with castration-resistant prostate cancer. It is not known whether adding enzalutamide to testosterone suppression, with or without early docetaxel, will improve survival in men with metastatic, hormone-sensitive prostate cancer. METHODS: In this open-label, randomized, phase 3 trial, we assigned patients to receive testosterone suppression plus either open-label enzalutamide or a standard nonsteroidal antiandrogen therapy (standard-care group). The primary end point was overall survival. Secondary end points included progression-free survival as determined by the prostate-specific antigen (PSA) level, clinical progression-free survival, and adverse events. RESULTS: A total of 1125 men underwent randomization; the median follow-up was 34 months. There were 102 deaths in the enzalutamide group and 143 deaths in the standard-care group (hazard ratio, 0.67; 95% confidence interval [CI], 0.52 to 0.86; P = 0.002). Kaplan-Meier estimates of overall survival at 3 years were 80% (based on 94 events) in the enzalutamide group and 72% (based on 130 events) in the standard-care group. Better results with enzalutamide were also seen in PSA progression-free survival (174 and 333 events, respectively; hazard ratio, 0.39; P<0.001) and in clinical progression-free survival (167 and 320 events, respectively; hazard ratio, 0.40; P<0.001). Treatment discontinuation due to adverse events was more frequent in the enzalutamide group than in the standard-care group (33 events and 14 events, respectively). Fatigue was more common in the enzalutamide group; seizures occurred in 7 patients in the enzalutamide group (1%) and in no patients in the standard-care group. CONCLUSIONS: Enzalutamide was associated with significantly longer progression-free and overall survival than standard care in men with metastatic, hormone-sensitive prostate cancer receiving testosterone suppression. The enzalutamide group had a higher incidence of seizures and other toxic effects, especially among those treated with early docetaxel. (Funded by Astellas Scientific and Medical Affairs and others; ENZAMET (ANZUP 1304) ANZCTR number, ACTRN12614000110684; ClinicalTrials.gov number, NCT02446405; and EU Clinical Trials Register number, 2014-003190-42.).

Protocol for the P3BEP trial (ANZUP 1302): an international randomised phase 3 trial of accelerated versus standard BEP chemotherapy for adult and paediatric male and female patients with intermediate and poor-risk metastatic germ cell tumours.

BACKGROUND: Bleomycin, etoposide, and cisplatin (BEP) chemotherapy administered every 3 weeks for 4 cycles remains the standard first line treatment for patients with intermediate- and poor-risk metastatic germ cell tumours (GCTs). Administering standard chemotherapy 2-weekly rather than 3-weekly, so-called 'accelerating chemotherapy', has improved cure rates in other cancers. An Australian multicentre phase 2 trial demonstrated this regimen is feasible and tolerable with efficacy data that appears promising. The aim of this trial is to determine if accelerated BEP is superior to standard BEP as first line chemotherapy for adult and paediatric male and female participants with intermediate and poor risk metastatic GCTs. METHODS: This is an open label, randomised, stratified, 2-arm, international multicentre, 2 stage, phase 3 clinical trial. Participants are randomised 1:1 to receive accelerated BEP or standard BEP chemotherapy. Eligible male or female participants, aged between 11 and 45 years with intermediate or poor-risk metastatic GCTs for first line chemotherapy will be enrolled from Australia, the United Kingdom and the United States. Participants will have regular follow up for at least 5 years. The primary endpoint for stage 1 of the trial (n = 150) is complete response rate and for the entire trial (n = 500) is progression free survival. Secondary endpoints include response following treatment completion (by a protocol-specific response criteria), adverse events, health-related quality of life, treatment preference, delivered dose-intensity of chemotherapy (relative to standard BEP), overall survival and associations between biomarkers (to be specified) and their correlations with clinical outcomes. DISCUSSION: This is the first international randomised clinical trial for intermediate and poor-risk metastatic extra-cranial GCTs involving both adult and pediatric age groups open to both males and females. It is also the largest, current randomised trial for germ cell tumours in the world. Positive results for this affordable intervention could change the global standard of care for intermediate and poor risk germ cell tumours, improve cure rates, avoid the need for toxic and costly salvage treatment, and return young adults to long, healthy and productive lives. TRIAL REGISTRATION: ACTRN 12613000496718 on 3rd May 2013 and Clinicaltrials.gov NCT02582697 on 21st October 2015.

What Survival Benefits are Needed to Make Adjuvant Sorafenib Worthwhile After Resection of Intermediate- or High-Risk Renal Cell Carcinoma? Clinical Investigators' Preferences in the SORCE Trial.

BACKGROUND: Decisions about adjuvant therapy involve trade-offs between possible benefits and harms. OBJECTIVE: We sought to determine the survival benefits that clinical investigators would judge as sufficient to warrant treatment with adjuvant sorafenib in the SORCE trial after nephrectomy for apparently localised renal cell carcinoma (RCC). METHODS: A subset of clinical investigators in the SORCE trial completed a validated questionnaire that elicited the minimum survival benefits they judged sufficient to warrant one year of adjuvant sorafenib in scenarios with hypothetical baseline survival times of 5 years and 15 years, and baseline survival rates at 5 years of 65% and 85%. RESULTS: The 100 participating SORCE investigators had a median age of 42 years, and 74 were male. For one year of sorafenib versus no therapy, the median benefits in survival times the investigators judged sufficient to warrant treatment were an extra nine months beyond five years and an extra 12 months beyond 15 years; the median benefits in survival rates were an extra 5% beyond baseline survival rates of both 65% and 85% at five years. The patients recruited in the SORCE trial by these investigators judged smaller benefits sufficient to warrant adjuvant sorafenib for both survival rate scenarios (p≤0.0001). The survival benefits the investigators judged sufficient to warrant one year of adjuvant therapy with sorafenib for RCC were similar to those of other clinicians considering three months of adjuvant chemotherapy for lung cancer, but smaller than those of clinicians considering six months of adjuvant chemotherapy for breast cancer. CONCLUSION: SORCE investigators judged larger benefits necessary to warrant adjuvant sorafenib than their patients. The benefits required by the investigators were similar or smaller than those other clinicians considered sufficient to warrant adjuvant chemotherapy for other cancers. Clinicians should recognise that their patients and colleagues may have preferences that differ from their own when considering the potential benefits and harms of adjuvant treatment.

Cell shape changes indicate a role for extrinsic tensile forces in Drosophila germ-band extension.

Drosophila germ-band extension (GBE) is an example of the convergence and extension movements that elongate and narrow embryonic tissues. To understand the collective cell behaviours underlying tissue morphogenesis, we have continuously quantified cell intercalation and cell shape change during GBE. We show that the fast, early phase of GBE depends on cell shape change in addition to cell intercalation. In antero-posterior patterning mutants such as those for the gap gene Krüppel, defective polarized cell intercalation is compensated for by an increase in antero-posterior cell elongation, such that the initial rate of extension remains the same. Spatio-temporal patterns of cell behaviours indicate that an antero-posterior tensile force deforms the germ band, causing the cells to change shape passively. The rate of antero-posterior cell elongation is reduced in twist mutant embryos, which lack mesoderm. We propose that cell shape change contributing to germ-band extension is a passive response to mechanical forces caused by the invaginating mesoderm.

Topical thymidine dinucleotide application protects against UVB-induced skin cancer in mice with DNA repair gene (Ercc1)-deficient skin.

Topical application of thymidine dinucleotides (pTpT) provides some protection against the effects of UV on the skin, however, many details of the protective mechanism have yet to be elucidated. We have used mice with an epidermis-specific knockout for the nucleotide excision repair gene, Ercc1, to investigate the mechanisms of protection. pTpT offered no protection against the pronounced UV-induced short-term erythema and skin thickening responses that are characteristic of DNA repair-deficient skin. It also had no effect on UV-induced apoptosis in Ercc1-deficient cultured keratinocytes. However, in these short-term experiments in both skin and keratinocyte culture pTpT did cause a slight reduction in proliferation. pTpT application during a chronic UV irradiation protocol provided some protection from UVB-induced skin carcinogenesis in epidermis-specific Ercc1 knockout mice. The median tumour free survival time was increased in the pTpT-treated group and treated animals had fewer tumours. In addition, pTpT-treated animals developed fewer large inwardly growing skin lesions than untreated animals. Furthermore, the proliferation response was reduced in chronically irradiated, non-lesional pTpT-treated skin. We conclude that cancer protection by pTpT in our mice is not modulated by an upregulation of DNA repair, as protection appears to be independent of a functional nucleotide excision repair pathway. We hypothesise instead that protection by pTpT is due to a reduction in epidermal proliferation.

The pro-apoptotic K-Ras 4A proto-oncoprotein does not affect tumorigenesis in the ApcMin/+ mouse small intestine.

BACKGROUND: Alterations in gene splicing occur in human sporadic colorectal cancer (CRC) and may contribute to tumour progression. The K-ras proto-oncogene encodes two splice variants, K-ras 4A and 4B, and K-ras activating mutations which jointly affect both isoforms are prevalent in CRC. Past studies have established that splicing of both the K-ras oncogene and proto-oncogene is altered in CRC in favour of K-ras 4B. The present study addressed whether the K-Ras 4A proto-oncoprotein can suppress tumour development in the absence of its oncogenic allele, utilising the ApcMin/+ (Min) mouse that spontaneously develops intestinal tumours that do not harbour K-ras activating mutations, and the K-rastmDelta4A/tmDelta4A mouse that can express the K-ras 4B splice variant only. By this means tumorigenesis in the small intestine was compared between ApcMin/+, K-ras+/+ and ApcMin/+, K-rastmDelta4A/tmDelta4A mice that can, and cannot, express the K-ras 4A proto-oncoprotein respectively. METHODS: The relative levels of expression of the K-ras splice variants in normal small intestine and small intestinal tumours were quantified by real-time RT-qPCR analysis. Inbred (C57BL/6) ApcMin/+, K-ras+/+ and ApcMin/+, K-rastmDelta4A/tmDelta4A mice were generated and the genotypes confirmed by PCR analysis. Survival of stocks was compared by the Mantel-Haenszel test, and tumour number and area compared by Student's t-test in outwardly healthy mice at approximately 106 and 152 days of age. DNA sequencing of codons 12, 13 and 61 was performed to confirm the intestinal tumours did not harbour a K-ras activating mutation. RESULTS: The K-ras 4A transcript accounted for about 50% of K-ras expressed in the small intestine of both wild-type and Min mice. Tumours in the small intestine of Min mice showed increased levels of K-ras 4B transcript expression, but no appreciable change in K-ras 4A transcript levels. No K-ras activating mutations were detected in 27 intestinal tumours derived from Min and compound mutant Min mice. K-Ras 4A deficiency did not affect mouse survival, or tumour number, size or histopathology. CONCLUSION: The K-Ras 4A proto-oncoprotein does not exhibit tumour suppressor activity in the small intestine, even though the K-ras 4A/4B ratio is reduced in adenomas lacking K-ras activating mutations.

A neurological phenotype in mice with DNA repair gene Ercc1 deficiency.

Transcription-coupled repair of endogenous DNA damage appears crucial for the maintenance of the central and peripheral nervous systems. Ercc1 is essential for nucleotide excision repair and is also involved in recombination repair and the repair of interstrand cross-links. We have investigated the neurological phenotype of Ercc1-deficient mice where the liver dysfunction has been corrected by an Ercc1 transgene controlled by a liver-specific promoter. We observed poor coordination, ataxia and loss of visual acuity, but saw no evidence of the anticipated histopathological neurodegeneration, or of abnormal neuromuscular junctions. Instead we observed uraemic encephalopathy, a brain disease resulting from kidney failure. This diagnosis was supported by histopathological signs of kidney disease, as well as proteinuria. When we examined archival sections from neural-specific Ercc1 knockout mice, which showed the same reduced growth and died at the same age as the liver-corrected Ercc1 knockouts, we found no evidence of kidney pathology or encephalopathy. Thus, while some aspects of the Ercc1-deficient phenotype are indicative of functional neurodegeneration, we obtained no structural evidence for this. The structural changes observed in the brains of liver-corrected Ercc1 knockouts appear to be a secondary consequence of kidney failure arising from Ercc1 deficiency.

Effects on kidney disease, fertility and development in mice inheriting a protein-truncating Denys-Drash syndrome allele (Wt1tmT396).

Denys-Drash syndrome (DDS) is caused by heterozygous mutations of the Wilms' tumour suppressor gene, WT1, characterised by early-onset diffuse mesangial sclerosis often associated with male pseudohermaphroditism and/or Wilms' tumourigenesis. Previously, we reported that the Wt1tmT396 allele induces DDS kidney disease in mice. In the present study heterozygotes (Wt1tmT396/+) were generated on inbred (129/Ola), crossbred (B6/129) and MF1 second backcross (MF1-N2) backgrounds. Whereas male heterozygotes on each background were fertile, inbred heterozygous females were infertile. Kidney disease (proteinuria and sclerosis) was not congenital and developed significantly earlier in inbred mice, although with variable onset. Disease onset in MF1-N2 stocks occurred later in Wt1tmT396/+ mice than reported previously for Wt1R394W/+ mice, and while no kidney disease has been reported in B6/129 Wt1+/- mice, B6/129 Wt1tmT396/+ mice were affected. Offspring of both male and female B6/129 and MF1-N2 Wt1tmT396/+ mice developed kidney disease, but its incidence was significantly higher in offspring of female heterozygotes. Wt1tmT396/tmT396 embryos exhibited identical developmental abnormalities to those reported for Wt1-/- embryos. The results indicate that the Wt1 (tmT396) allele does not predispose to Wilms' tumourigenesis or male pseudohermaphroditism, its effect on kidney disease and female fertility depends on genetic background, stochastic factors may affect disease onset, and disease transmission is subject to a partial parent-of-origin effect. Since the Wt1tmT396 allele has no detectable intrinsic functional activity in vivo, and kidney disease progression is affected by the type of Wt1 mutation, the data support the view that DDS nephropathy results from a dominant-negative action rather than WT1 haploinsufficiency or gain-of-function.

Deletion of genes implicated in protecting the integrity of male germ cells has differential effects on the incidence of DNA breaks and germ cell loss.

BACKGROUND: Infertility affects approximately 20% of couples in Europe and in 50% of cases the problem lies with the male partner. The impact of damaged DNA originating in the male germ line on infertility is poorly understood but may increase miscarriage. Mouse models allow us to investigate how deficiencies in DNA repair/damage response pathways impact on formation and function of male germ cells. We have investigated mice with deletions of ERCC1 (excision repair cross-complementing gene 1), MSH2 (MutS homolog 2, involved in mismatch repair pathway), and p53 (tumour suppressor gene implicated in elimination of germ cells with DNA damage). PRINCIPAL FINDINGS: We demonstrate for the first time that depletion of ERCC1 or p53 from germ cells results in an increased incidence of unrepaired DNA breaks in pachytene spermatocytes and increased numbers of caspase-3 positive (apoptotic) germ cells. Sertoli cell-only tubules were detected in testes from mice lacking expression of ERCC1 or MSH2 but not p53. The number of sperm recovered from epididymes was significantly reduced in mice lacking testicular ERCC1 and 40% of sperm contained DNA breaks whereas the numbers of sperm were not different to controls in adult Msh2 -/- or p53 -/- mice nor did they have significantly compromised DNA. CONCLUSIONS: These data have demonstrated that deletion of Ercc1, Msh2 and p53 can have differential but overlapping affects on germ cell function and sperm production. These findings increase our understanding of the ways in which gene mutations can have an impact on male fertility.