Lorlatinib and capmatinib in a ROS1-rearranged NSCLC with MET-driven resistance: tumor response and evolution

Acquired drug resistance remains a major problem across oncogene-addicted cancers. Elucidation of mechanisms of resistance can inform rational treatment strategies for patients relapsing on targeted therapies while offering insights into tumor evolution. Here, we report acquired MET amplification as a resistance driver in a ROS1-rearranged lung adenocarcinoma after sequential treatment with ROS1 inhibitors. Subsequent combination therapy with lorlatinib plus capmatinib, a MET-selective inhibitor, induced intracranial and extracranial tumor response. At relapse, sequencing of the resistant tumor revealed a MET D1246N mutation and loss of MET amplification. We performed integrated molecular analyses of serial tumor and plasma samples, unveiling dynamic alterations in the ROS1 fusion driver and MET bypass axis at genomic and protein levels and the emergence of polyclonal resistance. This case illustrates the complexity of longitudinal tumor evolution with sequential targeted therapies, highlighting challenges embedded in the current precision oncology paradigm and the importance of developing approaches that prevent resistance.

ALK-positive lung cancer: a moving target

Anaplastic lymphoma kinase (ALK) is a potent oncogenic driver in lung cancer. ALK tyrosine kinase inhibitors yield significant benefit in patients with ALK fusion-positive (ALK+) lung cancers; yet the durability of response is limited by drug resistance. Elucidation of on-target resistance mechanisms has facilitated the development of next-generation ALK inhibitors, but overcoming ALK-independent resistance mechanisms remains a challenge. In this Review, we discuss the molecular underpinnings of acquired resistance to ALK-directed therapy and highlight new treatment approaches aimed at inducing long-term remission in ALK+ disease.

A Phase 2 Study of Lorlatinib in Patients With ROS1-Rearranged Lung Cancer With Brain-Only Progression on Crizotinib

Introduction

The central nervous system (CNS) is a common site of progression among patients with ROS1-rearranged lung cancer receiving crizotinib. We conducted a phase 2 study to evaluate the intracranial efficacy of lorlatinib in patients with ROS1-rearranged lung cancer who developed CNS-only progression on crizotinib.

Methods

Patients with metastatic ROS1-rearranged lung cancer with CNS-only progression on crizotinib received lorlatinib 100 mg daily. The primary end point was intracranial disease control rate at 12 weeks per modified Response Evaluation Criteria in Solid Tumors version 1.1. Secondary end points included intracranial and extracranial progression-free survival, intracranial objective response rate, and safety/tolerability.

Results

A total of 16 patients were enrolled between November 2016 and January 2019. Nine patients (56%) had received prior CNS radiation, with a median of 10.9 months between radiation and lorlatinib. At 12 weeks, the intracranial disease control rate was 100% and intracranial objective response rate was 87%. While on study, the complee intracranial response rate was 60%. With median follow-up of 22 months, seven patients experienced disease progression, including five patients with CNS relapse. The median intracranial and extracranial progression-free survivals were 38.8 months (95% confidence interval: 16.9–not reported) and 41.1 months (95% confidence interval: 17.6–not reported), respectively. Molecular analysis of plasma or tissue from patients with extracranial progression on lorlatinib revealed ROS1 G2032R (n = 1), ROS1 L2086F (n = 1), and CCDC6-RET fusion plus ROS1 G2032R (n = 1). The safety profile of lorlatinib was consistent with prior studies. There were 11 patients (69%) who required dose reduction, including one patient who discontinued treatment for grade 3 edema. No grade greater than or equal to 4 adverse events were observed.

Conclusions

Lorlatinib induced durable intracranial responses in patients with ROS1-rearranged NSCLC and prior isolated CNS progression on crizotinib.

Response to Immune Checkpoint Inhibition as Monotherapy or in Combination With Chemotherapy in Metastatic ROS1-Rearranged Lung Cancers

INTRODUCTION

ROS1 fusions are oncogenic drivers in 1% to 3% of NSCLCs. The activity of immune checkpoint inhibitor (ICI) monotherapy or in combination with chemotherapy (chemotherapy with ICI [chemo-ICI]) in these tumors and their immunophenotype have not been systematically described.

METHODS

In this multi-institutional retrospective study, tumor programmed death-ligand 1 (PD-L1) expression and tumor mutational burden (TMB) were evaluated in patients with ROS1-rearranged NSCLC. Time-to-treatment discontinuation (TTD) and objective response rate (ORR) (Response Evaluation Criteria in Solid Tumors [RECIST] version 1.1) were calculated for patients treated with ICI or chemo-ICI in the metastatic setting.

RESULTS

A total of 184 patients were identified. Among 146 assessable cases, PD-L1 expression was less than 1% in 60 (41%), 1% to 49% in 35 (24%), and greater than or equal to 50% in 51 tumors (35%). Of 100 (92%) TMB-assessable tumors, 92 had less than 10 mutations per megabase. TMB was significantly lower for ROS1-rearranged tumors (n = 97) compared with tumors with EGFR (n = 1250) or KRAS alterations (n = 1653) and all other NSCLC tumors (n = 2753) evaluated with Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets (median TMB = 2.6 versus 3.5, 7.0, and 6.1 mutations per megabase, p < 0.001). Among patients treated with ICI, median TTD was 2.1 months (95% confidence interval [CI]: 1.0-4.2 mo; n = 28) and ORR 13% (2 of 16 RECIST-assessable; 95% CI: 2%-38%). Among patients treated with chemo-ICI, median TTD was 10 months (95% CI: 4.7-14.1 mo; n = 11) and ORR 83% (5 of 6 RECIST-assessable; 95% CI: 36%-100%). There was no difference in PD-L1 expression (p = 0.91) or TMB (p = 0.83) between responders and nonresponders.

CONCLUSIONS

Most ROS1-rearranged NSCLCs have low PD-L1 expression and TMB. The activity of ICI in these tumors is modest. In contrast, chemo-ICI can achieve meaningful activity.

The aging lung: Physiology, disease, and immunity

The population is aging at a rate never seen before in human history. As the number of elderly adults grows, it is imperative we expand our understanding of the underpinnings of aging biology. Human lungs are composed of a unique panoply of cell types that face ongoing chemical, mechanical, biological, immunological, and xenobiotic stress over a lifetime. Yet, we do not fully appreciate the mechanistic drivers of lung aging and why age increases the risk of parenchymal lung disease, fatal respiratory infection, and primary lung cancer. Here, we review the molecular and cellular aspects of lung aging, local stress response pathways, and how the aging process predisposes to the pathogenesis of pulmonary disease. We place these insights into context of the COVID-19 pandemic and discuss how innate and adaptive immunity within the lung is altered with age.

Serial ctDNA Monitoring to Predict Response to Systemic Therapy in Metastatic Gastrointestinal Cancers

PURPOSE

ctDNA offers a promising, noninvasive approach to monitor therapeutic efficacy in real-time. We explored whether the quantitative percent change in ctDNA early after therapy initiation can predict treatment response and progression-free survival (PFS) in patients with metastatic gastrointestinal cancer.

EXPERIMENTAL DESIGN

A total of 138 patients with metastatic gastrointestinal cancers and tumor profiling by next-generation sequencing had serial blood draws pretreatment and at scheduled intervals during therapy. ctDNA was assessed using individualized droplet digital PCR measuring the mutant allele fraction in plasma of mutations identified in tumor biopsies. ctDNA changes were correlated with tumor markers and radiographic response.

RESULTS

A total of 138 patients enrolled. A total of 101 patients were evaluable for ctDNA and 68 for tumor markers at 4 weeks. Percent change of ctDNA by 4 weeks predicted partial response (PR, P < 0.0001) and clinical benefit [CB: PR and stable disease (SD), P < 0.0001]. ctDNA decreased by 98% (median) and >30% for all PR patients. ctDNA change at 8 weeks, but not 2 weeks, also predicted CB (P < 0.0001). Four-week change in tumor markers also predicted response (P = 0.0026) and CB (P = 0.022). However, at a clinically relevant specificity threshold of 90%, 4-week ctDNA change more effectively predicted CB versus tumor markers, with a sensitivity of 60% versus 24%, respectively (P = 0.0109). Patients whose 4-week ctDNA decreased beyond this threshold (≥30% decrease) had a median PFS of 175 days versus 59.5 days (HR, 3.29; 95% CI, 1.55-7.00; P < 0.0001).

CONCLUSIONS

Serial ctDNA monitoring may provide early indication of response to systemic therapy in patients with metastatic gastrointestinal cancer prior to radiographic assessments and may outperform standard tumor markers, warranting further evaluation.

Abstract 1575: Circulating tumor DNA as a tool for predicting response to targeted therapy in gastrointestinal malignancies

Background: Patients with gastrointestinal (GI) malignancies undergoing treatment are surveyed for disease relapse with radiographic imaging and measurement of standard tumor markers. However, there is a need for more sensitive techniques to detect early cancer progression. Measurement of circulating tumor DNA (ctDNA) is emerging as an important diagnostic tool that can provide real-time information about disease response during treatment. In this study, we evaluated whether dynamic monitoring of ctDNA may predict cancer progression earlier than standard methods in patients with GI malignancies undergoing targeted therapy. Methods: Tumor and blood specimens were obtained from patients treated at the Massachusetts General Hospital (MGH) under IRB-approved studies. Tumor biopsies were performed at the time of diagnosis and were subjected to the MGH standard molecular diagnostics panel for 104 known cancer genes. Blood samples for ctDNA analysis were collected at baseline at the start of targeted therapy, and one more more driver mutations were followed longitudinaly at two week intervals starting one month after treatment. ctDNA was extracted from plasma using QIAGEN-based protocols and amplified by digital droplet PCR (ddPCR) using primers for tumor-specific point mutations. Tumor markers and CT scans were part of routine clinical care and procured using standard procedures at MGH. RECIST measurements, if available, were obtained in a blinded fashion using the Tumor Imaging Metrics Core. Results: We studied 44 patients with GI malignancies undergoing treatment with targeted therapies. Represented cancer types included colorectal (53%), gastroesophageal (21%), biliary (20%), and pancreatic cancers (6%). We correlated the % change in ctDNA mutant allele fraction (MAF) or standard tumor markers 4 weeks after treatment initiation with radiographic response by RECIST. Tumor-specific MAF decreased by 88% in patients who went on to show partial response (PR) or stable disease (SD), compared to an increase by 51% in patients shown to have progressive disease (PD) (p=1.8x10-5). All patients who achieved PR, except one, had a reduction in ctDNA levels by at least 93% or more. In contrast, standard tumor markers did not predict response as there was no significant difference in the % change at 4 weeks in the PR/SD group compared to PD (p=0.64). Conclusions: Real-time monitoring of patient-specific tumor mutations by ctDNA analysis has the potential to predict response to targeted therapy earlier than standard surveillance mechanisms. Integration of liquid biopsies into medical decision-making may allow for earlier identification of cancer progression and consequent modification of therapeutic approach. However, more studies are needed to determine whether incorporation of ctDNA analysis into clinical practice would impact patient outcomes.

Citation Format: Jaime L. Schneider, Aparna Parikh, Mehlika Rethinam, Brandon Nadres, Emily Van Seventer, Heather Shahzade, Ryan B. Corcoran. Circulating tumor DNA as a tool for predicting response to targeted therapy in gastrointestinal malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1575.

Patient actions and reactions after receiving negative results from expanded carrier screening

With the expansion of carrier screening to general preconception and prenatal patient populations, most patients will receive negative results, which we define as indicating <25% risk of having a child with a genetic condition. Because there is limited experience with expanded carrier screening, it is important to understand how receiving negative results affects patients, especially as providers, payers, and policymakers consider whether to offer it. In this mixed-methods study, we asked preconception patients enrolled in the NextGen study about their expectations and experiences receiving negative expanded carrier screening results. Participants completed surveys at study enrollment (n = 110 women, 51 male partners), after receiving carrier results (n = 100 women, 38 male partners), after receiving secondary findings (n = 98 women, 36 male partners), and 6 months after receiving results (n = 95 women, 28 male partners). We also interviewed a subset of participants 12 to 24 months after receiving results (n = 24 women, 12 male partners). We found minimal negative emotional impact and privacy concerns, increased confidence in reproductive plans, and few changes to health behaviors, although some patients made health decisions based on misunderstandings of their results. These findings suggest that expanded carrier screening causes minimal psychosocial harms, but systems are needed to reduce the risk of misinterpreting results.

Autophagy and Schizophrenia: A Closer Look at How Dysregulation of Neuronal Cell Homeostasis Influences the Pathogenesis of Schizophrenia

Autophagy, the process of degrading intracellular components in lysosomes, plays an important role in the central nervous system by contributing to neuronal homeostasis. Autophagic failure has been linked to neurologic dysfunction and a variety of neurodegenerative diseases. Recent investigation has revealed a novel role for autophagy in the context of mental illness, namely in schizophrenia. This article summarizes the phenomenology, genetics, and structural/histopathological brain abnormalities associated with schizophrenia. We review studies that demonstrate for the first time a connection between autophagy malfunction and schizophrenia. Transcriptional profiling in schizophrenia patients uncovered a dysregulation of autophagy-related genes spatially confined to a specific area of the cortex, Brodmann Area 22, which has been previously implicated in the positive symptoms of schizophrenia. We also discuss the role of autophagy activators in schizophrenia and whether they may be useful adjuvants to the traditional antipsychotic medications currently used as the standard of care. In summary, the field has progressed beyond the basic concept that autophagy impairment predisposes to neurodegeneration, to a mechanistic understanding that loss of autophagy can disrupt neuronal cell biology and predispose to mood disorders, psychotic symptoms, and behavioral change.

Risk of gastric cancer, gastrointestinal cancers and other cancers: a comparison of treatment with pantoprazole and other proton pump inhibitors

BACKGROUND

Proton pump inhibitors (PPIs) have been shown to be carcinogenic in rodent studies.

AIM

As part of a long-term post-marketing surveillance study requested by the US Food and Drug Administration, to compare incidence rates of gastric and other cancers after sustained exposures to pantoprazole, a long-acting PPI, compared with other shorter acting PPIs.

METHODS

We conducted a cohort study within the membership of the Kaiser Permanente Northern California healthcare system and compared rates of gastric and other cancers among pantoprazole users and users of other PPI medications. The Cox proportional hazards model was used to adjust for potential confounders such as sex, age, receipt of treatment for Helicobacter pylori, cumulative PPI dose, total years PPI treatment and year of index date. The study was developed in consultation with, and approved by, the FDA.

RESULTS

A total of 61 684 persons with at least a 240-day supply of medication (34 178 pantoprazole and 27 686 other PPIs) were followed up for a total of 547 020 person-years (274 700 vs. 272 321 person-years, respectively). The primary analyses demonstrated comparable risks between the pantoprazole and other PPI groups for gastric cancer [hazard ratio (HR) = 0.68, 95% CI 0.24-1.93); colorectal, liver, pancreatic, or small bowel cancers (HR = 0.95, 95% CI 0.65-1.40) or any cancer (HR = 1.06, 95% CI 0.93-1.21).

CONCLUSIONS

We found no evidence that pantoprazole, a longer acting PPI, compared with shorter-acting agents, conferred an excess risk of gastric cancer, other gastrointestinal cancers or all cancers for pantoprazole compared with other shorter-acting PPIs.

Loss of hepatic chaperone-mediated autophagy accelerates proteostasis failure in aging

Chaperone-mediated autophagy (CMA), a cellular process that contributes to protein quality control through targeting of a subset of cytosolic proteins to lysosomes for degradation, undergoes a functional decline with age. We have used a mouse model with liver-specific defective CMA to identify changes in proteostasis attributable to reduced CMA activity in this organ with age. We have found that other proteolytic systems compensate for CMA loss in young mice which helps to preserve proteostasis. However, these compensatory responses are not sufficient for protection against proteotoxicity induced by stress (oxidative stress, lipid challenges) or associated with aging. Livers from old mice with CMA blockage exhibit altered protein homeostasis, enhanced susceptibility to oxidative stress and hepatic dysfunction manifested by a diminished ability to metabolize drugs, and a worsening of the metabolic dysregulation identified in young mice. Our study reveals that while the regulatory function of CMA cannot be compensated for in young organisms, its contribution to protein homeostasis can be handled by other proteolytic systems. However, the decline in the compensatory ability identified with age explains the more severe consequences of CMA impairment in older organisms and the contribution of CMA malfunction to the gradual decline in proteostasis and stress resistance observed during aging.

Deficient chaperone-mediated autophagy in liver leads to metabolic dysregulation

The activity of chaperone-mediated autophagy (CMA), a catabolic pathway for selective degradation of cytosolic proteins in lysosomes, decreases with age, but the consequences of this functional decline in vivo remain unknown. In this work, we have generated a conditional knockout mouse to selectively block CMA in liver. We have found that blockage of CMA causes hepatic glycogen depletion and hepatosteatosis. The liver phenotype is accompanied by reduced peripheral adiposity, increased energy expenditure, and altered glucose homeostasis. Comparative lysosomal proteomics revealed that key enzymes in carbohydrate and lipid metabolism are normally degraded by CMA and that impairment of their regulated degradation contributes to the metabolic abnormalities observed in CMA-defective animals. These findings highlight the involvement of CMA in regulating hepatic metabolism and suggest that the age-related decline in CMA may have a negative impact on the energetic balance in old organisms.

Autophagy and human disease: emerging themes

Malfunction of autophagy, the process that mediates breakdown and recycling of intracellular components in lysosomes, has been linked to a variety of human diseases. As the number of pathologies associated with defective autophagy increases, emphasis has switched from the mere description of the status of autophagy in these conditions to a more mechanistic dissection of the autophagic changes. Understanding the reasons behind the autophagic defect, the immediate consequences of the autophagic compromise and how autophagy changes with the evolution of the disease has become a 'must,' especially now that manipulation of autophagy is being considered as a therapeutic strategy. Here, we comment on some of the common themes that have emerged from such detailed analyses of the interplay between autophagy and disease conditions.

Multistate outbreak of multidrug-resistant Salmonella newport infections associated with ground beef, October to December 2007

In late October 2007, an outbreak of multidrug-resistant Salmonella Newport infections affected 42 case patients in California, Arizona, Idaho, and Nevada. A case-control study implicated ground beef from one chain store. Despite detailed ground beef purchase histories--including shopper card information for several case patients--traceback efforts by both the U.S. Department of Agriculture, Food Safety and Inspection Service and the California Department of Public Health were unable to identify the source of contamination. Case patients consumed multiple types of ground beef products purchased at numerous chain store A retail locations. These stores had received beef products for grinding from multiple beef slaughter-processing establishments. Detailed retail grinding logs and grinding policies that prevent cross-contamination between batches of ground beef products are crucial in the identification of contaminated beef products associated with foodborne illness.

Shear stress induced reorganization of the keratin intermediate filament network requires phosphorylation by protein kinase C zeta

Keratin intermediate filaments (KIFs) form a fibrous polymer network that helps epithelial cells withstand external mechanical forces. Recently, we established a correlation between the structure of the KIF network and its local mechanical properties in alveolar epithelial cells. Shear stress applied across the cell surface resulted in the structural remodeling of KIF and a substantial increase in the elastic modulus of the network. This study examines the mechanosignaling that regulates the structural remodeling of the KIF network. We report that the shear stress-mediated remodeling of the KIF network is facilitated by a twofold increase in the dynamic exchange rate of KIF subunits, which is regulated in a PKC zeta and 14-3-3-dependent manner. PKC zeta phosphorylates K18pSer33, and this is required for the structural reorganization because the KIF network in A549 cells transfected with a dominant negative PKC zeta, or expressing the K18Ser33Ala mutation, is unchanged. Blocking the shear stress-mediated reorganization results in reduced cellular viability and increased apoptotic levels. These data suggest that shear stress mediates the phosphorylation of K18pSer33, which is required for the reorganization of the KIF network, resulting in changes in mechanical properties of the cell that help maintain the integrity of alveolar epithelial cells.

The association of Parkinson's disease with bone mineral density and fracture in older women

Among community-dwelling older women, compared to those without Parkinson's disease (PD), women with PD have 7.3% lower BMD and an increased risk for hip fracture (HR = 2.6).

INTRODUCTION

Studies reporting an association of Parkinson's disease (PD) with low bone mineral density (BMD) and increased fracture risk often have been prone to selection bias, and have not accounted for potentially important explanatory variables, including recent weight loss. Further, little is known about the association between PD and non-hip fractures. Consequently, we investigated the independent association of PD with hip BMD and long-term fracture risk.

METHODS

Associations of self-reported PD with hip BMD and incident hip and non-spine, non-hip fracture were analyzed using linear regression and Cox proportional hazards, respectively. This prospective cohort study analyzed 8,105 older women with known PD status (n = 73 with PD) at four US clinical centers of the Study of Osteoporotic Fractures.

RESULTS

Compared to women without PD, age-adjusted mean total hip BMD was 7.3% lower in women with PD. Women with PD had a 2.6-fold higher age-adjusted risk for incident hip fracture. Parkinson's disease was not significantly associated with non-spine, non-hip fractures.

CONCLUSIONS

In age-adjusted models, women with PD had lower hip BMD and increased hip fracture risk, associations that were no longer significant after further weight and multivariate adjustment. Older women with PD should be considered for evaluation and treatment to reduce their fracture risk.

Procedures for preventing the transmission of foot-and-mouth disease virus to pigs and sheep by personnel in contact with infected pigs

The most effective method of containing an outbreak of foot-and-mouth disease (FMD) is by the culling of livestock. However, qualified people must diagnose the disease before the culling can begin, and they must avoid susceptible animals after having been in contact with infected premises, to prevent them from transmitting the virus. To test the effectiveness of biosecurity procedures in preventing the transmission of FMD virus (O/UK/35/2001) investigators contacted and sampled pigs inoculated with FMD virus for approximately 45 minutes and then contacted and sampled sentinel pigs and sheep after either using no biosecurity procedures, or washing their hands and donning clean outerwear, or showering and donning clean outerwear. The virus was detected in the nasal secretions of one investigator immediately after the postmortem investigation of the inoculated pigs but was not detected in samples collected between approximately 12 and 84 hours later. After the contaminated personnel had showered and changed into clean outerwear they did not transmit the strain of FMD virus to susceptible pigs and sheep.

[The impact of substitution treatment by methadone among opiate-dependent subjects evaluated by Addiction Severity Index and by urine tests]

Methadone maintenance treatment (MMT) has been evaluated in the United States and in a few other countries. MMT has been developed in France since 1995, and over 5 000 patients receive this treatment. However no French study has yet been published on the efficacy of MMT as assessed by a validated scale. Retention in treatment for one year has been considered as a threshold to define maintenance of treatment benefits after discharge from a methadone program; determination of retention predictors is important. Over a three year period, we evaluated patients at admission and during treatment using the Addiction Severity Index (ASI), and urine drug screening was performed weekly; 95 patients (66 males and 29 females) were evaluated at intake. Their mean age was 30.2 5.5, and they had used opioids for a mean of 10.6 5.7 years. Their ASI severity scores for drugs were over 5, showing a clear need for treatment. Female patients differed from males only in the employment-finances ASI score; 43 patients completed at least one year of treatment, after which their drug and legal composite scores significantly improved. No significant changes in their consumption of cocaine, alcohol, benzodiazepines or cannabis were found, but they smoked fewer cigarettes at 12 months. Demographics, ASI severity scores, and history of suicide attempts did not differentiate one-year completers from dropouts (n=16). However, dropouts had used more buprenorphine and less methadone in the 30 days preceding their admission, and they received a lower dose of methadone during treatment. Our population is comparable to other French MMT populations; they enter treatment after a long history of opioid dependence. The improvement found on the ASI composite scores is also similar to the improvement described in other international studies. Dropouts in our study seem to be more treatment-resistant patients, in the sense that they had used more buprenorphine before intake and were not stabilized with it; and they may have had a more negative attitude towards methadone.

Using step-wise linear regression to detect "functional" sequence variants: application to simulated data

Step-wise linear regression was used to detect the "functional" sequence variant in gene 6 responsible for phenotypic variation in traits Q1 and Q2. Prior to analysis, single-nucleotide polymorphisms (SNPs) that were in complete or near complete linkage disequilibrium were binned. In total, we identified 11 separate alleles (or allelic bins). Analyses were performed on all 50 replicates. The "functional" allele variant in gene 6 (at position 5782) accounted for 24% of the variation in Q1 and 11% of the variation in Q2. We detected a significant association between this SNP and Q1 in 90% of the replicates (i.e., in 45 of 50 replicates) and between this SNP and Q2 in 78% of the replicates. Although significant associations were also observed with some nonfunctional SNPs, our results nevertheless suggest that simple step-wise regression may play a useful role in analyzing sequence data. Some additional extensions to this approach are suggested.

Genome-wide scan of obesity in the Old Order Amish

To identify the genetic determinants of typical obesity, we performed a genome-wide scan of obesity-related traits using data from the Amish. Multipoint linkage analysis was performed using a variance components procedure on body mass index (BMI), waist circumference, percentage of body fat, and serum leptin concentrations. All 672 individuals were genotyped for 357 markers in 22 autosomes. We observed modest evidence for linkage, with the maximum log odds (lod) scores for linkage for these traits occurring on chromosomes 3p (percentage of body fat: lod = 1.61, near the peroxisome proliferator-activated receptor-alpha gene), 14q (waist: lod = 1.80), and 16p (leptin: lod = 1.72; BMI: lod = 1.68). We also tested for linkage to BMI-adjusted leptin concentrations and observed suggestive evidence for linkage on chromosome 10p (lod = 2.73), approximately 10-20 cM telomeric from obesity loci previously reported in French and German Caucasians. Two additional linkage signals for this trait were observed on chromosomes 7q (lod = 1.77, approximately 20 cM from the leptin gene) and 14q (lod = 2.47). Follow-up studies may be warranted to pursue some of these linkage signals, especially those detected near known obesity candidate genes, and those in regions coinciding with linkage signals reported previously.

Power of variance component linkage analysis to detect epistasis

Variance component methods are now being used in linkage analysis to detect genes influencing complex diseases. These methods are easily extended to allow for simultaneous estimation of both the additive effects of multiple loci on phenotypic variation (conditional oligogenic analysis) and the additive interaction (epistatic) effects among loci. We performed linkage analyses on 200 of the simulated replicates in order to evaluate the power to detect the main effects of MG1 and MG2 on Q1 as well as their interaction effects. The power to detect the main effect of MG1 was moderately good, although the power to detect MG2 and the MG1 x MG2 interaction was poor.

QTL influencing blood pressure maps to the region of PPH1 on chromosome 2q31-34 in Old Order Amish

BACKGROUND

Hypertension is a major risk factor for coronary heart disease, stroke, congestive heart failure, renal insufficiency, and peripheral vascular disease. Although the genetic contribution to variation in blood pressure is well recognized, the specific genes involved are mostly unknown. We carried out a genome-wide scan to identify loci influencing blood pressure in the Old Order Amish population of Lancaster County, Pennsylvania.

METHODS AND RESULTS

Blood pressures were measured in 694 adult participants from families recruited without regard to blood pressure. We performed a quantitative linkage analysis by using 357 microsatellite markers. In multipoint analysis, strong evidence for linkage was observed with both diastolic (lod=3.36; P=0.00004) and to a lesser extent systolic (lod=1.64; P=0.003) blood pressure in the region of chromosome 2q31-34. Peak evidence for linkage occurred at map positions 217 and 221 cM from pter for diastolic and systolic blood pressure, respectively.

CONCLUSIONS

A gene linked to familial primary pulmonary hypertension has recently been mapped to this same region, suggesting the intriguing hypothesis that other (attenuated) mutations in this same gene may influence variation in systolic and diastolic blood pressure in this population.

Diabetes and hypertension in Mexican American families: relation to cardiovascular risk

There is a strong familial predisposition to type 2 diabetes, hypertension, and cardiovascular disease. The authors evaluated the association between a family history of these diseases and a large panel of cardiovascular risk factors in 1,431 Mexican American subjects who were enrolled in the San Antonio Family Heart Study in San Antonio, Texas. The baseline phase of the study covered 1992-1996. Diabetes and hypertension were diagnosed according to standard clinical criteria, while cardiovascular disease was defined as a history of heart attack or heart surgery. The prevalence of diabetes, hypertension, and cardiovascular disease in this population was 15%, 12%, and 3%, respectively. For each unaffected subject, the authors computed a family history score based on the presence or absence of disease in parents and older siblings, and correlations between cardiovascular risk factors and family history scores were estimated by using likelihood-based variance component methods. Diabetes family history score was significantly correlated with a broad panel of cardiovascular risk factors, including glucose and insulin, obesity, blood pressure, triglycerides, and total cholesterol. Hypertension family history score was significantly correlated with glucose, blood pressure, body mass index, waist circumference, total cholesterol, and triglycerides. These results support the idea that genes that confer a risk for diabetes, and to a lesser extent hypertension, adversely alter the cardiovascular risk profile long before the manifestation of clinical disease.

High dietary fiber and low saturated fat intake among oligomenorrheic undergraduates

Numerous functional risk factors are associated with the occurrence of secondary amenorrhea in young women. Less is known regarding factors associated with the more prevalent problem of oligomenorrhea. We have evaluated nutrient intake, body composition, perceived psychological stress, 24-hour urinary cortisol, and urinary C peptide (UCP) in 35 eumenorrheic, 11 mildly oligomenorrheic, and 10 oligomenorrheic nonathletic undergraduate women. Nutrient intake was evaluated by a validated food frequency questionnaire. Oligomenorrheic women were found to consume significantly more dietary fiber, crude fiber, and polyunsaturated fat, and significantly less saturated fat than their eumenorrheic classmates. Oligomenorrheic women had significantly lower 24-hour UCP excretion than mildly oligomenorrheic women. The groups did not differ in any aspect of body composition, body weight, age of menarche, perceived psychological stress, or urinary cortisol excretion. The data suggest that higher intake of fiber and lower intake of saturated fat may be associated with oligomenorrhea among otherwise healthy undergraduate nonathletic women.