Testing a Cloud-Based Model for Active Surveillance of Medical Devices with Analyses of Coronary Stent Safety Using the Data Extraction and Longitudinal Trend Analysis (DELTA) System.

Objective: To demonstrate the use of the Data Extraction and Longitudinal Trend Analysis (DELTA) system in the National Evaluation System for health Technology's (NEST) medical device surveillance cloud environment by analyzing coronary stent safety using real world clinical data and comparing results to clinical trial findings. Design and Setting: Electronic health record (EHR) data from two health systems, the Social Security Death Master File, and device databases were ingested into the NEST cloud, and safety analyses of two stents were performed using DELTA. Participants and Interventions: This is an observational study of patients receiving zotarolimus drug-eluting coronary stents (ZES) or everolimus eluting coronary stents (EES) between July 1, 2015 and December 31, 2017. Results: After exclusions, 3334 patients receiving EES and 1002 receiving ZES were available for study. Analysis using inverse probability weighting showed no significant difference in one-year mortality or major adverse cardiac events (MACE) for EES compared to ZES [Mortality Odds Ratio 0.94 (95% CI 0.81-1.175); p = 0.780] [MACE Odds Ratio 1.04 (95% CI 0.92-1.16; p = 0.551]). Analysis using propensity matching showed no significant difference in EES one-year mortality (547 of 992 alive and available after censoring) compared to ZES (546 of 992) [Log-Rank statistic 0.3348 (p = 0.563)]. Conclusion: Automated cloud-based medical device safety surveillance using EHR data is feasible and was efficiently performed using DELTA. No statistically significant differences in 1-year safety outcomes between ZES and EES were identified using two statistical approaches, consistent with randomized trial findings.

Real-World Safety Analysis of Paclitaxel Devices Used for the Treatment of Peripheral Artery Disease.

PURPOSE: To investigate the real-world safety of paclitaxel (PTX)-coated devices for treating lower extremity peripheral artery disease using a commercial claims database. MATERIALS AND METHODS: Data from FAIR Health, the largest commercial claims data warehouse in the United States, were used for this study. The study consisted of patients who underwent femoropopliteal revascularization procedures between January 1, 2015, and December 31, 2019, with PTX and non-PTX devices. The primary outcome was 4-year survival following treatment. The secondary outcomes included 2-year survival, 2- and 4-year freedom from amputation, and repeat revascularization. Propensity score matching was used to minimize confounding, and the Kaplan-Meier methods were used to estimate survival. RESULTS: A total of 10,832 procedures were included in the analysis, including 4,962 involving PTX devices and 5,870 involving non-PTX devices. PTX devices were associated with a reduced hazard of death following treatment at 2 and 4 years (hazard ratio [HR], 0.74 [95% confidence interval {CI}, 0.69-0.79]; P <.05, and HR, 0.89 [95% CI, 0.77-1.02]; log-rank P =.018, respectively). The risk of amputation was also lower following treatment with PTX devices than with non-PTX devices at 2 and 4 years (HR, 0.82 [95% CI, 0.76-0.87]; P =.02, and HR, 0.77 [95% CI, 0.67-0.89]; log-rank P =.01, respectively). In addition, the odds of repeat revascularization were similar with PTX and non-PTX devices at 2 and 4 years. CONCLUSIONS: In the real-world commercial claims database, no short- or long-term signal for increased mortality or amputations was observed following treatment with PTX devices.

Evaluation of intervertebral body implant performance using active surveillance of electronic health records.

Objectives: To assess the feasibility of using electronic health record (EHR) derived clinical data within an active surveillance setting to evaluate the safety of a novel intervertebral body implant (IVBI) stabilization device. Design: Retrospective, longitudinal observational cohort study comparing clinical outcomes for patients seen through 1 year following spinal fusion surgery. Setting: Lahey Health network, which includes academic tertiary hospitals, outpatient clinics, and independent provider offices in the New England region of the USA. Participants: All spine surgery patients aged 18 or older who underwent thoracic or lumbar spinal arthrodesis surgeries were included. Main outcome measures: The clinical outcomes of patients treated with the CONCORDE Bullet (CB) interbody spine system (DePuy) between April 2015 and December 2018 were compared with those patients receiving alternative spine stabilization interbody device implants. The primary endpoint was reoperation rate at 1 year, with secondary endpoints including the requirement for blood transfusion during index hospitalization, 1 year rate of any cause hospitalization, 1 year rate of surgical site infection, and mortality at 1 year. Results: Among the 606 patients undergoing thoracic or lumbar spinal fusion surgery during the study period, 136 received only the CB. In comparison with patients who did not receive the CB, no significant differences were found in the rate of reoperation at 1 year or the rates of secondary safety outcomes. Conclusions: Data derived from the EHR can be successfully leveraged to assess the safety of IVBI devices, in this case demonstrating no significant differences in the rates of risk-adjusted safety endpoints between patients undergoing spinal surgery with the CB as compared with alternative spinal implants.

Vascular Quality Initiative Surveillance of Femoropopliteal Artery Paclitaxel Devices.

OBJECTIVES: This study sought to determine the safety and efficacy of paclitaxel (PTX) devices in the treatment of peripheral artery disease involving the femoropopliteal artery. BACKGROUND: A meta-analysis of PTX devices for the treatment of femoropopliteal artery disease reported a mortality signal. METHODS: This was a multicenter cohort study using an integrated clinical data surveillance system to conduct a prospective, propensity score-matched survival analysis of 2,456 patients in the Society for Vascular Surgery Vascular Quality Initiative from January 2017 to May 2020. The study compared PTX drug-coated balloon angioplasty versus percutaneous transluminal balloon angioplasty, PTX drug-eluting stents versus bare-metal stents, and any PTX device versus any non-PTX device. The primary outcome was 2-year survival. Secondary endpoints were successful ambulation and interventional success. RESULTS: Treatment with any PTX device versus any non-PTX device was associated with increased 2-year survival (89.5% vs 86.7%; HR: 0.79; 95% CI: 0.72-0.87; P = 0.004), improved interventional success (81.6% vs 77.6%; HR: 0.82; 95% CI: 0.74-0.91; P < 0.001), and higher rates of independent ambulation at 1 year (86.0% vs 83.4%; HR: 0.85; 95% CI: 0.79-0.91; P = 0.008). Treatment with PTX drug-coated balloon angioplasty was associated with improved survival at 2 years (88.9% vs 85.7%; HR: 0.77; 95% CI: 0.70-0.86; P = 0.005), while PTX drug-eluting stent therapy was associated with similar survival compared with bare-metal stent therapy (91.3% vs 89.6%; HR: 0.84; 95% CI: 0.70-1.01; P = 0.36). CONCLUSIONS: In this prospective, active surveillance of a national clinical registry, PTX-containing devices were associated with increased survival at 2 years and improved clinical outcomes at 1 year. (VQI DELTA Paclitaxel Device Safety Analysis [VQI-PTX]; NCT04110288).

Active Surveillance of the Implantable Cardioverter-Defibrillator Registry for Defibrillator Lead Failures.

BACKGROUND: Several defibrillator leads have been recalled due to early lead failure leading to significant patient harm. Confirming the safety of contemporary defibrillator leads is essential to optimizing treatment for patients receiving implantable cardioverter-defibrillators (ICDs). We therefore sought to assess the comparative long-term safety of the 4 most commonly implanted ICD leads within the National Cardiovascular Data Registry ICD Registry. METHODS AND RESULTS: A propensity-matched survival analysis of the ICD Registry was performed evaluating 4 contemporary ICD leads in patients receiving an ICD system for the first time. All patients in the ICD Registry aged ≥18 years who underwent an implant of an ICD between April 1, 2011 and March 31, 2016 were included. Monitoring of safety began with ICD implant and continued up to 5 years. A meaningful difference in ICD failure rate was defined as twice (or more) the lead failure rate observed in the propensity-matched comparator patients. Among the 374 132 patients who received a new ICD implant, no safety alerts were triggered for the primary safety end point of lead failure for any of the high energy leads studied. Estimated rates of freedom from lead failure at 5 years ranged from 97.7% to 98.9% for the 4 high-energy leads of interest. CONCLUSIONS: Though limited by incomplete long-term outcomes ascertainment, active surveillance of the ICD Registry suggests that there were no meaningful differences in the rate of ICD high-energy lead survival for the 4 most commonly used high-energy ICD leads.

Impact of early surveillance on safety signal identification in the CathPCI DELTA study.

OBJECTIVES: The CathPCI Data Extraction and Longitudinal Trend Analysis study was designed to determine the feasibility of conducting prospective surveillance of a large national registry to perform comparative safety analyses of medical devices. We sought to determine whether the complementary use of retrospective case data could improve safety signal detection time. DESIGN: We performed a simulated surveillance study of the comparative safety of the Mynx vascular closure device (VCD) with propensity score matched alternate VCD recipients, using both retrospective and prospective cohort data. SETTING: Centers within the USA using the National Cardiovascular Data Registry (NCDR) CathPCI Registry. PARTICIPANTS: Percutaneous coronary intervention cases captured within the NCDR CathPCI Registry from July 1, 2009 to September 30, 2013 were included in the analysis. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Absolute and relative risk (RR) of any vascular complication (a composite of bleeding at access site, hematoma at access site, retroperitoneal bleeding, and other vascular complications requiring treatment); time to signal detection. RESULTS: A safety alert was detected for the primary outcome of "any vascular complication" after 15 months of surveillance and was sustained for the study duration (absolute risk of any vascular complication, 1.20% vs 0.73%, RR, 1.63; 95% CI 1.50 to 1.79; p<0.001). The safety signal was identified 12 months earlier with the use of retrospective case data than during the initial study. CONCLUSIONS: Prospective, active surveillance of cardiovascular registries is feasible to perform comparative analyses of medical devices. Retrospective data may complement prospective surveillance to improve time to signal detection, indicating the need for earlier prospective application of safety surveillance for devices new to the market.

Comparative Safety of Aspiration Thrombectomy Catheters Utilizing Prospective, Active Surveillance of the NCDR CathPCI Registry.

Background Current strategies for ensuring the postmarket safety of medical devices are limited by small sample size and reliance on voluntary reporting of adverse events. Prospective, active surveillance of clinical registries may provide early warnings in the postmarket evaluation of medical device safety but has not been demonstrated in national clinical data registries. Methods and Results The CathPCI DELTA (Data Extraction and Longitudinal Trend Analysis) study was designed to assess the feasibility of prospective, active safety surveillance of medical devices within a national cardiovascular registry. We sought to assess the ability of our surveillance strategy to avoid false safety alerts by conducting an active safety surveillance study of aspiration thrombectomy catheters using data within the National Cardiovascular Data Registry CathPCI registry, where no difference in safety outcomes were anticipated for the primary in-hospital safety outcome of death and major adverse cardiovascular events (MACE). We performed a propensity-matched analysis of 5 aspiration thrombectomy catheter devices used during percutaneous coronary intervention among 95 925 patients presenting with ST-segment-elevation myocardial infarction between January 1, 2011 and September 30, 2013. After 33 months of surveillance, no safety alerts were triggered for the primary safety endpoints of death or MACE, with no between-catheter differences observed. The absolute risk of death during acute hospitalization ranged from 5.11% to 5.32% among the most commonly used aspiration thrombectomy catheter devices, with relative risks for death ranging from 0.96 to 1.03. The absolute risk of MACE ranged from 9.78% to 10.18%, with relative risks for MACE ranging from 0.99 to 1.02. There were no statistically significant differences in the rates of death or MACE between any of the aspiration thrombectomy catheter devices analyzed. Conclusions The CathPCI DELTA study demonstrates that prospective, active safety surveillance of national clinical registries is feasible to provide near-real-time safety assessments of new medical devices.

Registry-Based Prospective, Active Surveillance of Medical-Device Safety.

BACKGROUND: The process of assuring the safety of medical devices is constrained by reliance on voluntary reporting of adverse events. We evaluated a strategy of prospective, active surveillance of a national clinical registry to monitor the safety of an implantable vascular-closure device that had a suspected association with increased adverse events after percutaneous coronary intervention (PCI). METHODS: We used an integrated clinical-data surveillance system to conduct a prospective, propensity-matched analysis of the safety of the Mynx vascular-closure device, as compared with alternative approved vascular-closure devices, with data from the CathPCI Registry of the National Cardiovascular Data Registry. The primary outcome was any vascular complication, which was a composite of access-site bleeding, access-site hematoma, retroperitoneal bleeding, or any vascular complication requiring intervention. Secondary safety end points were access-site bleeding requiring treatment and postprocedural blood transfusion. RESULTS: We analyzed data from 73,124 patients who had received Mynx devices after PCI procedures with femoral access from January 1, 2011, to September 30, 2013. The Mynx device was associated with a significantly greater risk of any vascular complication than were alternative vascular-closure devices (absolute risk, 1.2% vs. 0.8%; relative risk, 1.59; 95% confidence interval [CI], 1.42 to 1.78; P<0.001); there was also a significantly greater risk of access-site bleeding (absolute risk, 0.4% vs. 0.3%; relative risk, 1.34; 95% CI, 1.10 to 1.62; P=0.001) and transfusion (absolute risk, 1.8% vs. 1.5%; relative risk, 1.23; 95% CI, 1.13 to 1.34; P<0.001). The initial alerts occurred within the first 12 months of monitoring. Relative risks were greater in three prespecified high-risk subgroups: patients with diabetes, those 70 years of age or older, and women. All safety alerts were confirmed in an independent sample of 48,992 patients from April 1, 2014, to September 30, 2015. CONCLUSIONS: A strategy of prospective, active surveillance of a clinical registry rapidly identified potential safety signals among recipients of an implantable vascular-closure device, with initial alerts occurring within the first 12 months of monitoring. (Funded by the Food and Drug Administration and others.).

Assessing the cost burden of United States FDA-mandated post-approval studies for medical devices.

Approved medical devices frequently undergo FDA mandated post-approval studies (PAS). However, there is uncertainty as to the value of PAS in assessing the safety of medical devices and the cost of these studies to the healthcare system is unknown. Since PAS costs are funded through device manufacturers who do not share the costs with regulators, we sought to estimate the total PAS costs through interviews with a panel of experts in medical device clinical trial design in order to design a general cost model for PAS which was then applied to the FDA PAS. A total of 277 PAS were initiated between 3/1/05 through 6/30/13 and demonstrated a median cost of $2.16 million per study and an overall cost of $1.22 billion over the 8.25 years of study. While these costs are funded through manufacturers, the ultimate cost is borne by the healthcare system through the medical device costs. Given concerns regarding the informational value of PAS, the resources used to support mandated PAS may be better allocated to other approaches to assure safety.

The data extraction and longitudinal trend analysis network study of distributed automated postmarket cardiovascular device safety surveillance.

BACKGROUND: Current approaches for postmarket medical device safety surveillance are limited in their ability to produce timely and accurate assessments of adverse event rates. METHODS AND RESULTS: The Data Extraction and Longitudinal Trend Analysis (DELTA) network study was a multicenter prospective observational study designed to evaluate the safety of devices used during percutaneous coronary interventions. All adult patients undergoing percutaneous coronary intervention from January 2008 to December 2012 at 5 participating Massachusetts sites were included. A safety alert was triggered if the cumulative observed adverse event rates for the study device exceeded the upper 95% confidence interval of the event rates of propensity-matched control cohort. Prespecified sensitivity analyses were developed to validate any identified safety signal. A total of 23,805 consecutive percutaneous coronary intervention procedures were evaluated. Two of 24 safety analyses triggered safety alerts. Patients receiving Perclose vascular closure device experienced an increased risk of minor vascular complications (relative risk, 4.14; P<0.01) and any vascular complication (relative risk, 2.06; P=0.01) when compared with propensity-matched patients receiving alternative vascular closure device, a result primarily driven by relatively high event rates at 1 participating center. Sensitivity analyses based on alternative risk adjustment methods confirmed a pattern of increased rate of complications at 1 of the 5 participating sites in their use of Perclose vascular closure device. CONCLUSIONS: The DELTA network study demonstrates that distributed automated prospective safety surveillance has the potential of providing near real-time assessment of safety risks of newly approved medical devices.

Overweight among children younger than 3 years in a low-income patient population: prevalence in 2010.

OBJECTIVES: To examine the prevalence and correlates of overweight and obesity among patients aged 0 to 2 years, and to compare 3 measures of early childhood weight status, weight-for-age, weight-for-length, and body mass index-for-age. SETTING: Well-child visits in the Philadelphia Health Centers, public community health centers providing primary health care to predominantly low-income residents. STUDY DESIGN: Cross-sectional. RESULTS: Using the 3 measures, 13% to 16% of boys and 10% to 13% of girls seen during 2010 were classified as high in weight. No consistent associations with feeding method were identified. "Other/unknown" race was consistently associated with higher rates of overweight than the African American reference group. Hispanic girls had higher rates of high weight-for-age and weight-for-length than African American girls. CONCLUSION: Elevated weight status emerges in a significant proportion of very young children, by all of the commonly used weight measures. There is an urgent need for appropriate clinical strategies to prevent and respond to overweight in this age group.

Severe obesity and high blood pressure among children, Philadelphia health centers, 2010.

BACKGROUND: Child obesity is a major health problem particularly affecting disadvantaged population groups. Severe obesity carries additional health risks for children. In the context of the childhood obesity epidemic, high blood pressure among children is of increasing concern. METHODS: Chart reviews were carried out to examine the prevalence of severe obesity and its association with high blood pressure measurements among randomly selected patients aged 3 to 17 years who had well-child care visits at 8 public community health centers during 2010. RESULTS: A majority of the 691 patients reviewed were African American (58%); an additional 16% were Hispanic. The prevalence of severe obesity was 7.7% (95% confidence interval = 5.8% to 9.9%) and the prevalence of high blood pressure measurements was 17.5% (95% confidence interval = 14.8% to 20.6%). Patients who were severely obese were more than twice as likely as other children to have high blood pressure values. CONCLUSIONS: Severe obesity is associated with substantially increased frequency of high blood pressure measurements in children, and should be investigated further as a potential marker for hypertension in children. Primary care providers should be prepared to diagnose and treat hypertension in severely obese children.

Risk-treatment paradox in the selection of transradial access for percutaneous coronary intervention.

BACKGROUND: Access site complications contribute to morbidity and mortality during percutaneous coronary intervention (PCI). Transradial arterial access significantly lowers the risk of access site complications compared to transfemoral arteriotomy. We sought to develop a prediction model for access site complications in patients undergoing PCI with femoral arteriotomy, and assess whether transradial access was selectively used in patients at high risk for complications. METHODS AND RESULTS: We analyzed 17 509 patients who underwent PCI without circulatory support from 2008 to 2011 at 5 institutions. Transradial arterial access was used in 17.8% of patients. In those who underwent transfemoral access, 177 (1.2%) patients had access site complications. Using preprocedural clinical and demographic data, a prediction model for femoral arteriotomy complications was generated. The variables retained in the model included: elevated age (P<0.001), female gender (P<0.001), elevated troponin (P<0.001), decreased renal function or dialysis (P=0.002), emergent PCI (P=0.01), prior PCI (P=0.005), diabetes (P=0.008), and peripheral artery disease (P=0.003). The model showed moderate discrimination (optimism-adjusted c-statistic=0.72) and was internally validated via bootstrap resampling. Patients with higher predicted risk of complications via transfemoral access were less likely to receive transradial access (P<0.001). Similar results were seen in patients presenting with and without ST-segment myocardial infarction and when adjusting for individual physician operator. CONCLUSIONS: We generated and validated a model for transfemoral access site complications during PCI. Paradoxically, patients most likely to develop access site complications from transfemoral access, and therefore benefit from transradial access, were the least likely to receive transradial access.

Vascular closure device failure in contemporary practice.

OBJECTIVES: The goal of this study was to assess the frequency and predictors of vascular closure device (VCD) deployment failure, and its association with vascular complications of 3 commonly used VCDs. BACKGROUND: VCDs are commonly used following percutaneous coronary intervention on the basis of studies demonstrating reduced time to ambulation, increased patient comfort, and possible reduction in vascular complications as compared with manual compression. However, limited data are available on the frequency and predictors of VCD failure, and the association of deployment failure with vascular complications. METHODS: From a de-identified dataset provided by Massachusetts Department of Health, 23,813 consecutive interventional coronary procedures that used either a collagen plug-based (n = 18,533), a nitinol clip-based (n = 2,284), or a suture-based (n = 2,996) VCD between June 2005 and December 2007 were identified. The authors defined VCD failure as unsuccessful deployment or failure to achieve immediate access site hemostasis. RESULTS: Among 23,813 procedures, the VCD failed in 781 (3.3%) procedures (2.1% of collagen plug-based, 6.1% of suture-based, 9.5% of nitinol clip-based VCDs). Patients with VCD failure had an excess risk of "any" (7.7% vs. 2.8%; p < 0.001), major (3.3% vs. 0.8%; p < 0.001), or minor (5.8% vs. 2.1%; p < 0.001) vascular complications compared with successful VCD deployment. In a propensity score-adjusted analysis, when compared with collagen plug-based VCD (reference odds ratio [OR] = 1.0), nitinol clip-based VCD had 2-fold increased risk (OR: 2.0, 95% confidence interval [CI]: 1.8 to 2.3, p < 0.001) and suture-based VCD had 1.25-fold increased risk (OR: 1.25, 95% CI: 1.2 to 1.3, p < 0.001) for VCD failure. VCD failure was a significant predictor of subsequent vascular complications for both collagen plug-based VCD and nitinol clip-based VCD, but not for suture-based VCD. CONCLUSIONS: VCD failure rates vary depending upon the type of VCD used and are associated with significantly higher vascular complications as compared with deployment successes.

Breastfeeding in an inner-city patient population.

In order to determine the proportion of infants seen in safety-net health clinics whose mothers initiated and sustained breastfeeding and to assess predictors of breastfeeding in this largely minority patient population, charts were reviewed for infants treated in the eight Philadelphia Health Centers. Breastfeeding was initiated by 42%; 7.5% breastfed for 180 or more days. Race/ethnicity, mother's age, birth weight, and prematurity were not associated with breastfeeding initiation or maintenance. There were differences in initiation rates between patients born in different hospitals, and between patients seen in different health centers. Hospital and health center differences in breastfeeding initiation and health center differences in breastfeeding maintenance may reflect practice variations and unmeasured differences in patient populations. While breastfeeding rates in this population remain far below targets, the substantial proportion of mothers who did breastfeed and large variations between facilities demonstrate that breastfeeding is possible and can be successfully promoted among economically disadvantaged mothers.

Absence of polo-like kinase 3 in mice stabilizes Cdc25A after DNA damage but is not sufficient to produce tumors.

The polo-like kinases (Plks1-5) are emerging as an important class of proteins involved in many facets of cell cycle regulation and response to DNA damage and stress. Here we show that Plk3 phosphorylates the key cell cycle protein phosphatase Cdc25A on two serine residues in its cyclinB/cdk1 docking domain and regulates its stability in response to DNA damage. We generated a Plk3 knock-out mouse and show that Cdc25A protein from Plk3-deficient cells is less susceptible to DNA damage-mediated degradation than cells with functional Plk3. We also show that absence of Plk3 correlates with loss of the G1/S cell cycle checkpoint. However, neither this compromised DNA damage checkpoint nor reduced susceptibility to proteasome-mediated degradation after DNA damage translated into a significant increase in tumor incidence in the Plk3-deficient mice.

A human cancer-predisposing polymorphism in Cdc25A is embryonic lethal in the mouse and promotes ASK-1 mediated apoptosis.

BACKGROUND: Failure to regulate the levels of Cdc25A phosphatase during the cell cycle or during a checkpoint response causes bypass of DNA damage and replication checkpoints resulting in genomic instability and cancer. During G1 and S and in cellular response to DNA damage, Cdc25A is targeted for degradation through the Skp1-cullin-ß-TrCP (SCFß-TrCP) complex. This complex binds to the Cdc25A DSG motif which contains serine residues at positions 82 and 88. Phosphorylation of one or both residues is necessary for the binding and degradation to occur. RESULTS: We now show that mutation of serine 88 to phenylalanine, which is a cancer-predisposing polymorphic variant in humans, leads to early embryonic lethality in mice. The mutant protein retains its phosphatase activity both in vitro and in cultured cells. It fails to interact with the apoptosis signal-regulating kinase 1 (ASK1), however, and therefore does not suppress ASK1-mediated apoptosis. CONCLUSIONS: These data suggest that the DSG motif, in addition to its function in Cdc25A-mediated degradation, plays a role in cell survival during early embyogenesis through suppression of ASK1-mediated apoptosis.

Chk2*1100delC Acts in synergy with the Ron receptor tyrosine kinase to accelerate mammary tumorigenesis in mice.

The CHEK2 (Chk2 in mice) polymorphic variant, CHEK2*1100delC, leads to genomic instability and is associated with an increased risk for breast cancer. The Ron receptor tyrosine kinase is overexpressed in a large fraction of human breast cancers. Here, we asked whether the low penetrance Chk2*1100delC allele alters the tumorigenic efficacy of Ron in the development of mammary tumors in a mouse model. Our data demonstrate that Ron overexpression on a Chk2*1100delC background accelerates the development of mammary tumors, and shows that pathways mediated by a tyrosine kinase receptor and a regulator of the cell cycle can act to hasten tumorigenesis in vivo.

Mice with the CHEK2*1100delC SNP are predisposed to cancer with a strong gender bias.

The CHEK2 kinase (Chk2 in mouse) is a member of a DNA damage response pathway that regulates cell cycle arrest at cell cycle checkpoints and facilitates the repair of dsDNA breaks by a recombination-mediated mechanism. There are numerous variants of the CHEK2 gene, at least one of which, CHEK2*1100delC (SNP), associates with breast cancer. A mouse model in which the wild-type Chk2 has been replaced by a Chk2*1100delC allele was tested for elevated risk of spontaneous cancer and increased sensitivity to challenge by a carcinogenic compound. Mice homozygous for Chk2*1100delC produced more tumors than wild-type mice, whereas heterozygous mice were not statistically different. When fractionated by gender, however, homozygous and heterozygous mice developed spontaneous tumors more rapidly and to a far greater extent than wild-type mice, indicative of a marked gender bias in mice harboring the variant allele. Consistent with our previous data showing elevated genomic instability in mouse embryonic fibroblasts (MEFs) derived from mice homozygous for Chk2*1100delC, the level of Cdc25A was elevated in heterozygous and homozygous MEFs and tumors. When challenged with the carcinogen 7,12-dimethylbenz[a]anthracene, all mice, regardless of genotype, had a reduced lifespan. Latency for mammary tumorigenesis was reduced significantly in mice homozygous for Chk2*1100delC but unexpectedly increased for the development of lymphomas. An implication from this study is that individuals who harbor the variant CHEK2*1100delC allele not only are at an elevated risk for the development of cancer but also that this risk can be further increased as a result of environmental exposure.