A Phase I Dose-escalation Study of AZD3965, an Oral Monocarboxylate Transporter 1 Inhibitor, in Patients with Advanced Cancer

PURPOSE

Inhibition of monocarboxylate transporter (MCT) 1-mediated lactate transport may have cytostatic and/or cytotoxic effects on tumor cells. We report results from the dose-escalation part of a first-in-human trial of AZD3965, a first-in-class MCT1 inhibitor, in advanced cancer.

PATIENTS AND METHODS

This multicentre, phase I, dose-escalation and dose-expansion trial enrolled patients with advanced solid tumors or lymphoma and no standard therapy options. Exclusion criteria included history of retinal and/or cardiac disease, due to MCT1 expression in the eye and heart. Patients received daily oral AZD3965 according to a 3+3 then rolling six design. Primary objectives were to assess safety and determine the MTD and/or recommended phase II dose (RP2D). Secondary objectives for dose escalation included measurement of pharmacokinetic and pharmacodynamic activity. Exploratory biomarkers included tumor expression of MCT1 and MCT4, functional imaging of biological impact, and metabolomics.

RESULTS

During dose escalation, 40 patients received AZD3965 at 5-30 mg once daily or 10 or 15 mg twice daily. Treatment-emergent adverse events were primarily grade 1 and/or 2, most commonly electroretinogram changes (retinopathy), fatigue, anorexia, and constipation. Seven patients receiving ≥20 mg daily experienced dose-limiting toxicities (DLT): grade 3 cardiac troponin rise (n = 1), asymptomatic ocular DLTs (n = 5), and grade 3 acidosis (n = 1). Plasma pharmacokinetics demonstrated attainment of target concentrations; pharmacodynamic measurements indicated on-target activity.

CONCLUSIONS

AZD3965 is tolerated at doses that produce target engagement. DLTs were on-target and primarily dose-dependent, asymptomatic, reversible ocular changes. An RP2D of 10 mg twice daily was established for use in dose expansion in cancers that generally express high MCT1/low MCT4).

Project Optimus, an FDA initiative: Considerations for cancer drug development internationally, from an academic perspective

Modern cancer therapeutics are increasingly targeted, bringing the promise of new and improved activity, alongside better tolerability. However, while many are indeed resulting in dramatic improvements in disease control and patient survival, short- and long-term tolerability has not always accompanied it. The choice of dose and schedule is often in the upper range of the therapeutic window, driven by the maximum tolerated dose (MTD) model of previous cytotoxic agents. There is increasing recognition that this needs to change, by taking a more holistic approach to determine the optimal dose for desired biological effects and tolerability early in clinical development. In the US, the FDA's Oncology Centre of Excellence is addressing this via the Project Optimus initiative: aiming to reform dose optimisation studies so that they can demonstrate the most appropriate dose selection. Early clinical development will need to demonstrate the dose-exposure, -pharmacodynamic, -toxicity and -activity relationships, including randomised evaluations for dose selection. Regulatory agencies outside the US are similarly exploring this. Along with Australia, Brazil, Canada, Israel, Singapore and Switzerland, the UK participates in Project Orbis, a collaborative program with the FDA to accelerate patient access to new cancer medicines through coordinated regulatory review. Close alignment with Project Optimus will be important internationally and will require changes across industry, including for academic units and small biotech. We discuss our perspective on the implications, and opportunities, for early phase oncology trials as a uniquely charity-funded drug development facility, the Centre for Drug Development within the Cancer Research UK charity.

SPIKE-1: A Randomised Phase II/III trial in a community setting, assessing use of camostat in reducing the clinical progression of COVID-19 by blocking SARS-CoV-2 Spike protein-initiated membrane fusion

OBJECTIVES

The primary objective is to evaluate the efficacy of camostat to prevent respiratory deterioration in patients with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection. Secondary objectives include assessment of the ability of camostat to reduce the requirement for Coronavirus disease 2019 (COVID-19) related hospital admission and to reduce the requirement for supplementary oxygen and ventilation as treatment for SARS-CoV-2 infection, to evaluate overall mortality related to COVID-19 and to evaluate the efficacy of camostat by effect on clinical improvement. Research objectives include to assess change in COVID-19 symptom severity, to evaluate the ability of camostat to reduce viral load throughout duration of illness as well as translational research on host and viral genomics, serum antibody production, COVID-19 diagnostics, and validation of laboratory testing methods and biomarkers.

TRIAL DESIGN

SPIKE-1 is a randomised, multicentre, prospective, open label, community-based clinical trial. Eligible patients will be randomised 1:1 to the camostat treatment arm and control arm (best supportive care). The trial is designed to include a pilot phase recruiting up to 50 patients in each arm. An initial review at the end of the pilot phase will allow assessment of available data and inform the requirement for any protocol adaptations to include refinement of eligibility criteria to enrich the patient population and sample size calculations. Up to 289 additional patients will be randomised in the continuation phase of the trial. A formal interim analysis will be performed once 50% of the maximum sample size has been recruited PARTICIPANTS: The trial will recruit adults (≥ 18 years) who score moderate to very high risk according to COVID-age risk calculation, with typical symptoms of COVID-19 infection as per Public Health England guidance or equivalent organisations in the UK, Health Protection Scotland, Public Health Wales, Public Health Agency (Northern Ireland) and with evidence of current COVID-19 infection from a validated assay. The trial is being conducted in the UK and patients are recruited through primary care and hospital settings.

INTERVENTION AND COMPARATOR

Eligible patients with be randomised to receive either camostat tablets, 200 mg four times daily (qds) for 14 days (treatment arm) or best supportive care (control arm).

MAIN OUTCOMES

Primary outcome measure: the rate of hospital admissions requiring supplemental oxygen. Secondary outcome measures include: the rate of COVID-19 related hospital admission in patients with SARS-CoV-2 infection; the number of supplementary oxygen-free days and ventilator-free days measured at 28 days from randomisation; the rate of mortality related to COVID-19 one year from randomisation; the time to worst point on the nine-point category ordinal scale (recommended by the World Health Organization: Coronavirus disease (COVID-2019)) or deterioration of two points or more, within 28 days from randomisation. Research outcomes include the assessment of change in COVID-19 symptom severity on days 1-14 as measured by (1) time to apyrexia (maintained for 48 hrs) by daily self-assessment of temperature, time to improvement (by two points) in peripheral oxygenation saturation defined by daily self-assessment of fingertip peripheral oxygenation saturation levels, (3) assessment of COVID-19 symptoms using the Flu-iiQ questionnaire (determined by app recording and/or daily video call (or phone) consultation and (4) assessment of functional score (where possible) at screening, day 7 and 14. The ability of camostat to reduce viral load throughout duration of illness will be assessed by (1) change in respiratory (oropharyngeal/nasopharyngeal swab RT-PCR) log10 viral load from baseline to Days 7 and 14, (2) change in respiratory (saliva RT-PCR) log10 viral load from baseline to Days 1-14 and (3) change in upper respiratory viral shedding at Day 1 -14 measured as time to clearance of nasal SARS-CoV-2, defined as 2 consecutive negative swabs by qPCR. Additional translational research outcomes include assessment of host and viral genomics, serum antibody production and COVID-19 diagnostics at baseline and on Days 7 and 14.

RANDOMISATION

Eligible patients will be randomised using an interactive web response system (IWRS) in a 1:1 ratio to one of two arms: (1) treatment arm or (2) control arm.

BLINDING (MASKING)

The trial is open-label.

NUMBERS TO BE RANDOMISED (SAMPLE SIZE)

The trial is designed to include a pilot and a continuation phase. Up to 100 patients (randomised 1:1 treatment and control arm) will be recruited in the pilot phase and a maximum of 289 patients (randomised 1:1 treatment and control) will be recruited as part of the continuation phase. The total number of patients recruited will not exceed 389.

TRIAL STATUS

Protocol version number v3 25 September 2020. Trial opened to recruitment on 04 August 2020. The authors anticipate recruitment to be completed by October 2021.

TRIAL REGISTRATION

EudraCT 2020-002110-41; 18 June 2020 ClinicalTrials.gov NCT04455815 ; 02 July 2020 FULL PROTOCOL: The full protocol is attached as an additional file, accessible from the Trials website (Additional file 1). Unpublished PK data provided under confidentiality agreement to the trial Sponsor has been removed from the background section of the protocol to allow for publication of the trial protocol. In the interest in expediting dissemination of this material, the familiar formatting has been eliminated; this Letter serves as a summary of the key elements of the full protocol.

Pharmacokinetics, safety, and tolerability of olaparib and temozolomide for recurrent glioblastoma: results of the phase I OPARATIC trial

BACKGROUND

The poly(ADP-ribose) polymerase (PARP) inhibitor olaparib potentiated radiation and temozolomide (TMZ) chemotherapy in preclinical glioblastoma models but brain penetration was poor. Clinically, PARP inhibitors exacerbate the hematological side effects of TMZ. The OPARATIC trial was conducted to measure penetration of recurrent glioblastoma by olaparib and assess the safety and tolerability of its combination with TMZ.

METHODS

Preclinical pharmacokinetic studies evaluated olaparib tissue distribution in rats and tumor-bearing mice. Adult patients with recurrent glioblastoma received various doses and schedules of olaparib and low-dose TMZ in a 3 + 3 design. Suitable patients received olaparib prior to neurosurgical resection; olaparib concentrations in plasma, tumor core and tumor margin specimens were measured by mass spectrometry. A dose expansion cohort tested tolerability and efficacy of the recommended phase II dose (RP2D). Radiosensitizing effects of olaparib were measured by clonogenic survival in glioblastoma cell lines.

RESULTS

Olaparib was a substrate for multidrug resistance protein 1 and showed no brain penetration in rats but was detected in orthotopic glioblastoma xenografts. Clinically, olaparib was detected in 71/71 tumor core specimens (27 patients; median, 496 nM) and 21/21 tumor margin specimens (9 patients; median, 512.3 nM). Olaparib exacerbated TMZ-related hematological toxicity, necessitating intermittent dosing. RP2D was olaparib 150 mg (3 days/week) with TMZ 75 mg/m2 daily for 42 days. Fourteen (36%) of 39 evaluable patients were progression free at 6 months. Olaparib radiosensitized 6 glioblastoma cell lines at clinically relevant concentrations of 100 and 500 nM.

CONCLUSION

Olaparib reliably penetrates recurrent glioblastoma at radiosensitizing concentrations, supporting further clinical development and highlighting the need for better preclinical models.

Correction: A case of malignant hyperlactaemic acidosis appearing upon treatment with the mono-carboxylase transporter 1 inhibitor AZD3965

Since the publication of this paper the authors noticed an error in the listed authors, where Alexandros Siskos was listed as Alexandros Sitkos. This has now been corrected.

A case of malignant hyperlactaemic acidosis appearing upon treatment with the mono-carboxylase transporter 1 inhibitor AZD3965

A 47-year-old man with metastatic melanoma presented with refractory hyperlactaemic acidosis following the first dose of the mono-carboxylase transporter 1 inhibitor AZD3965 within a "first time in man" clinical trial. The mechanism of the agent and the temporal relationship suggested that this event was potentially drug related and recruitment was suspended. However, urinary metabolomics showed extensive abnormalities even prior to drug administration, leading to investigations for an underlying metabolic disorder. The lack of clinical symptoms from the elevated lactate and low blood glucose suggested a diagnosis of "hyper-Warburgism", where the high tumour burden was associated with extensive glucose uptake and lactate efflux from malignant cells, and the subsequent impact on blood biochemistry. This was supported by an FDG-PET scan showing extensive glucose uptake in numerous metastases and lack of uptake in the brain. A review of the literature showed 16 case reports of "hyper-Warburgism" in non-haematological malignancies, none of them with melanoma, with most associated with a poor outcome. The patient was treated symptomatically, but died 2 months later. The development of AZD3965 continues with the exclusion of patients with elevated plasma lactate at screening added to the protocol as a safety measure.Trial identification number ClinicalTrials.Gov. NCT01791595.

A phase I trial of the γ-secretase inhibitor MK-0752 in combination with gemcitabine in patients with pancreatic ductal adenocarcinoma

BACKGROUND

The Notch pathway is frequently activated in cancer. Pathway inhibition by γ-secretase inhibitors has been shown to be effective in pre-clinical models of pancreatic cancer, in combination with gemcitabine.

METHODS

A multi-centre, non-randomised Bayesian adaptive design study of MK-0752, administered per os weekly, in combination with gemcitabine administered intravenously on days 1, 8 and 15 (28 day cycle) at 800 or 1000 mg m-2, was performed to determine the safety of combination treatment and the recommended phase 2 dose (RP2D). Secondary and tertiary objectives included tumour response, plasma and tumour MK-0752 concentration, and inhibition of the Notch pathway in hair follicles and tumour.

RESULTS

Overall, 44 eligible patients (performance status 0 or 1 with adequate organ function) received gemcitabine and MK-0752 as first or second line treatment for pancreatic cancer. RP2Ds of MK-0752 and gemcitabine as single agents could be combined safely. The Bayesian algorithm allowed further dose escalation, but pharmacokinetic analysis showed no increase in MK-0752 AUC (area under the curve) beyond 1800 mg once weekly. Tumour response evaluation was available in 19 patients; 13 achieved stable disease and 1 patient achieved a confirmed partial response.

CONCLUSIONS

Gemcitabine and a γ-secretase inhibitor (MK-0752) can be combined at their full, single-agent RP2Ds.

A first-in-human phase I study to determine the maximum tolerated dose of the oral Src/ABL inhibitor AZD0424

BACKGROUND

Src is involved in cancer invasion and metastasis. AZD0424, an oral inhibitor of Src and ABL1, has shown evidence of anti-tumour activity in pre-clinical studies.

METHODS

A phase Ia, dose escalation study was performed to assess the safety of continuous oral dosing with AZD0424 in advanced solid tumours. Secondary objectives included investigation of AZD0424 pharmacokinetics, effect on Src activity using markers of bone turnover, and anti-tumour activity.

RESULTS

41 patients were treated; 34 received AZD0424 once-daily at doses ranging from 5 mg to 150 mg, and 7 received 40 mg bi-daily 41.5% of patients experienced at least one AZD0424-related adverse event that was Grade 3-5 in severity, with patients treated at doses above 60 mg per day experiencing multiple treatment-related toxicities. The most commonly observed AZD0424-related adverse events were nausea, fatigue, anorexia and alopecia. Cmax and AUC increased linearly with dose and the mean±standard deviation t1/2 was 8.4±2.8 h. Clear evidence of Src target inhibition was seen at doses ⩾20 mg per day. No responses were observed and 7 patients (17.1%) achieved stable disease lasting 6 weeks or more.

CONCLUSIONS

AZD0424 displayed no evidence of efficacy as monotherapy despite a clear pharmacodynamic effect. Further evaluation of AZD0424 monotherapy in patients with solid tumours is not recommended.

Targeting Carcinoembryonic Antigen with DNA Vaccination: On-Target Adverse Events Link with Immunologic and Clinical Outcomes

PURPOSE

We have clinically evaluated a DNA fusion vaccine to target the HLA-A*0201-binding peptide CAP-1 from carcinoembryonic antigen (CEA605-613) linked to an immunostimulatory domain (DOM) from fragment C of tetanus toxin.

EXPERIMENTAL DESIGN

Twenty-seven patients with CEA-expressing carcinomas were recruited: 15 patients with measurable disease (arm-I) and 12 patients without radiological evidence of disease (arm-II). Six intramuscular vaccinations of naked DNA (1 mg/dose) were administered up to week 12. Clinical and immunologic follow-up was up to week 64 or clinical/radiological disease.

RESULTS

DOM-specific immune responses demonstrated successful vaccine delivery. All patients without measurable disease compared with 60% with advanced disease responded immunologically, while 58% and 20% expanded anti-CAP-1 CD8+ T cells, respectively. CAP-1-specific T cells were only detectable in the blood postvaccination but could also be identified in previously resected cancer tissue. The gastrointestinal adverse event diarrhea was reported by 48% of patients and linked to more frequent decreases in CEA (P < 0.001) and improved global immunologic responses [anti-DOM responses of greater magnitude (P < 0.001), frequency (P = 0.004), and duration] compared with patients without diarrhea. In advanced disease patients, decreases in CEA were associated with better overall survival (HR = 0.14, P = 0.017). CAP-1 peptide was detectable on MHC class I of normal bowel mucosa and primary colorectal cancer tissue by mass spectrometry, offering a mechanistic explanation for diarrhea through CD8+ T-cell attack.

CONCLUSIONS

Our data suggest that DNA vaccination is able to overcome peripheral tolerance in normal and tumor tissue and warrants testing in combination studies, for example, by vaccinating in parallel to treatment with an anti-PD1 antibody. Clin Cancer Res; 22(19); 4827-36. ©2016 AACR.

Trends in the characteristics, dose-limiting toxicities and efficacy of phase I oncology trials: The Cancer Research UK experience

INTRODUCTION

Phase I oncology trials have evolved over the years, and these changes could have implications for future studies and patients.

METHODS

Adult trials sponsored by Cancer Research UK Centre for Drug Development between 1995 and 2013 were analysed. Forty-nine trials were divided into two groups based on the starting date for recruitment: 1995-2003 (24 trials, n = 603) and 2004-2013 (25 trials, n = 750) for comparative purposes.

RESULTS

From 1995-2003 to 2004-2013, there was a shift towards studying non-cytotoxic agents that are administered orally. In later trials, patients tended to have better performance status, were older, had greater disease burden, and were more likely to have received prior treatment. In 2004-2013, wider variety of dose escalation designs were used, and studies were more likely to be multicentre, target/disease specific, conducted in first-/any-line setting and to require tumour biopsy. The overall incidence of dose-limiting toxicities (DLTs) was unchanged (10.9%; risk of death 0.4%), but DLTs such as neuropathy, stomatitis and thrombocytopaenia were less frequent in the more recent trials, while elevated liver enzymes were more frequent. Non-classical DLTs emerged in the later trials, including hypertension, hypophosphataemia, cardiac and ophthalmic toxicities. Disease control rate (DCR) increased from 27.9% (1995-2003) to 36.0% (2004-2013; P = 0.0033) due to higher rates of disease stabilisation.

CONCLUSION

Changes in trial designs, therapeutic agents, patient characteristics and DLTs were observed. Although the nature of DLTs changed, the incidence was similar in the two time periods and DCR improved, suggesting that the benefit-risk balance for patients participating in early-phase trials remains acceptable.

Phase 2 multicentre trial investigating intermittent and continuous dosing schedules of the poly(ADP-ribose) polymerase inhibitor rucaparib in germline BRCA mutation carriers with advanced ovarian and breast cancer

BACKGROUND

Rucaparib is an orally available potent selective small-molecule inhibitor of poly(ADP-ribose) polymerase (PARP) 1 and 2. Rucaparib induces synthetic lethality in cancer cells defective in the homologous recombination repair pathway including BRCA-1/2. We investigated the efficacy and safety of single-agent rucaparib in germline (g) BRCA mutation carriers with advanced breast and ovarian cancers.

METHODS

Phase II, open-label, multicentre trial of rucaparib in proven BRCA-1/2 mutation carriers with advanced breast and or ovarian cancer, WHO PS 0-1 and normal organ function. Intravenous (i.v.) and subsequently oral rucaparib were assessed, using a range of dosing schedules, to determine the safety, tolerability, dose-limiting toxic effects and pharmacodynamic (PD) and pharmacokinetic (PK) profiles.

RESULTS

Rucaparib was well tolerated in patients up to doses of 480 mg per day and is a potent inhibitor of PARP, with sustained inhibition ⩾24 h after single doses. The i.v. rucaparib (intermittent dosing schedule) resulted in an objective response rate (ORR) of only 2% but with 41% (18 out of 44) patients achieved stable disease for ⩾12 weeks and 3 patients maintaining disease stabilisation for >52 weeks. The ORR for oral rucaparib (across all six dose levels) was 15%. In the oral cohorts, 81% (22 out of 27) of the patients had ovarian cancer and 12 out of 13, who were dosed continuously, achieved RECIST complete response/partial response (CR/PR) or stable disease (SD) ⩾12 weeks, with a median duration of response of 179 days (range 84-567 days).

CONCLUSIONS

Rucaparib is well tolerated and results in high levels of PARP inhibition in surrogate tissues even at the lowest dose levels. Rucaparib is active in gBRCA-mutant ovarian cancer and this activity correlates with platinum-free interval. The key lessons learned from this study is that continuous rucaparib dosing is required for optimal response, the recommended phase 2 dose (RP2D) for continuous oral scheduling has not been established and requires further exploration and, thirdly, the use of a PD biomarker to evaluate dose-response has its limitations.

A phase 1 trial of intravenous 4-(N-(S-glutathionylacetyl)amino) phenylarsenoxide (GSAO) in patients with advanced solid tumours

BACKGROUND

4-(N-(S-glutathionylacetyl)amino) phenylarsenoxide (GSAO) is a water-soluble mitochondrial toxin that binds to adenine nucleotide translocase in the inner mitochondrial membrane, thereby targeting cell proliferation. This phase 1 study investigated safety, dose-limiting toxicities (DLTs), maximum tolerated dose (MTD) and pharmacokinetics (PK) of GSAO as a daily 1-h infusion for 5 days a week for 2 weeks in every three. Pharmacodynamics of GSAO was evaluated by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and circulating markers of angiogenesis.

METHODS

Patients with advanced solid tumours received GSAO in a dose-escalation trial according to a standard '3 + 3' design that was guided by toxicity and, for the final dose escalation, by arsenic PK data.

RESULTS

A total of 34 patients were treated with GSAO across 9 dose levels (1.3-44.0 mg/m(2)). Treatment was well tolerated with few adverse events. An additional three patients were enrolled at the 12.4 mg/m(2) dose level following a DLT of derangement of liver function tests (grade 4). At the 44.0 mg/m(2) dose level, two out of three patients had DLTs (reversible encephalopathy; paroxysmal atrial fibrillation).

CONCLUSIONS

The MTD of GSAO was 22.0 mg/m(2)/day. There was no biomarker evidence from DCE-MRI or circulating markers of angiogenesis of an anti-vascular effect of GSAO.

A novel Phase I/IIa design for early phase oncology studies and its application in the evaluation of MK-0752 in pancreatic cancer

The Cancer Research UK study CR0720-11 is a trial to determine the tolerability and effect on survival of using two agents in combination in patients with advanced pancreatic cancer. In particular, the trial is designed first to identify the most suitable combination of doses of the two agents in terms of the incidence of dose-limiting toxicities. Then, the survival of all patients who have received that dose combination in the study so far, together with additional patients assigned to that dose combination to ensure that the total number is sufficient, will be analysed. If the survival outcomes show promise, then a definitive randomised study of that dose combination will be recommended. The first two patients in the trial will be treated with the lowest doses of each agent in combination. An adaptive Bayesian procedure based only on monotonicity constraints concerning the risks of toxicity at different dose levels will then be used to suggest dose combinations for subsequent patients. The survival analysis will concern only patients who received the chosen dose combination, and will compare observed mortality with that expected from an exponential model based on the known survival rates associated with current treatment. In this paper, the Bayesian dose-finding procedure is described and illustrated, and its properties are evaluated through simulation. Computation of the appropriate sample size for the survival investigation is also discussed.

Randomized phase II study of decitabine in combination with carboplatin compared with carboplatin alone in patients with recurrent advanced ovarian cancer

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Background: Experimental and clinical data (Gifford et al, Clin Cancer Res. 2004) indicate the potential importance of methylation in mediating resistance to carboplatin in ovarian cancer. A previous phase I trial (Appleton et al, J Clin Oncol. 2007) established the feasibility of combining carboplatin with the demethylating agent decitabine on a day 1 + 8 q4 weekly (w) schedule and PD data provided evidence of target cell demethylation. Methods: Patients (pt) with ovarian cancer relapsing 6–12 months following first line treatment were randomised to receive either 6 cycles of carboplatin AUC 6 q4 w (Arm A), or 90 mg/m2 decitabine as a 6 hour infusion on day 1 and carboplatin AUC 6 on day 8 q4 w (Arm B). The primary endpoint was response rate. An interim analysis was planned after 11 patients were enrolled into Arm B. Results: 29 pt were enrolled. After the first 4 pt had been treated (at 90 mg/m2 decitabine) the frequency of dose delays due to neutropenia was considered unacceptable, and therefore the starting dose of decitabine was reduced to 45 mg/m2 for the subsequent 11 pt. 7 out of 14 pt in Arm A completed 6 cycles compared with 0 of 11 in Arm B (at 45 mg/m2 decitabine). Grade 2/3 hypersensitivity reactions were more common in Arm B than Arm A (64% vs. 21%), as were prolonged treatment delays due to neutropenia (36% vs. 10%). At the interim analysis, in the 11 pt treated with 45mg/m2 (Arm B), there were no RECIST responses, while 2 pt had short-lived CA125 responses (59 and 63 days). In contrast 6 of 14 patients in Arm A had RECIST responses consistent with the expected efficacy of carboplatin in this population. Conclusions: The lack of efficacy, as well as the difficulties in treatment delivery in Arm B, led the project team to conclude that the study should be closed. With this dose and schedule, decitabine is ineffective in reversing carboplatin resistance. Further investigations are ongoing to understand (a) the apparent increased incidence of hypersensitivity and (b) the trend towards reduced efficacy in Arm B.

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Most low-level microsatellite instability in colorectal cancers can be explained without an elevated slippage rate

Many cancers show a low level of microsatellite slippage and are labelled MSI-L (microsatellite instability--low). However, it is unclear whether this slippage can be attributed to some underlying genetic change that results in a mutator phenotype, analogous to mismatch repair deficiency in MSI-H cancers, or whether the apparent instability is the result of relatively frequent normal somatic slippage. Here, we have used a mathematical model of microsatellite slippage during cancer growth to estimate the degree of microsatellite slippage expected in a cancer due to normal somatic slippage. We compared the model to the slippage observed in 42 non-MSI-H cancers that were macro-dissected into four distinct regions and genotyped at N = 9 microsatellite loci. When the slippage rate was set at mu = 10(-5) per locus per division, ten cancers showed a level of slippage in at least one region that was too severe to be expected from normal somatic slippage alone, suggesting that these cancers had acquired MSI-L. Only one of these ten cancers had putative MSI-L in all four regions. When we considered a slightly higher slippage rate of mu = 5 x 10(-5), none of the cancers showed a degree of slippage that could not be reasonably explained by normal somatic slippage. Counting the number of 'unstable' loci was a poor indicator of putative MSI-L status. We conclude that most low-level microsatellite instability in colorectal cancers can be explained without requiring an elevated slippage rate during neoplastic development, and hence there is little evidence for a discrete MSI-L group of cancers. Putative MSI-L status is indicated by the presence of at least one locus that has multiple alleles that differ by at least five motif repeats from the germline. If an underlying genetic change does cause MSI-L, it appears to be a relatively uncommon event that occurs late in oncogenesis.

CDC4 mutations occur in a subset of colorectal cancers but are not predicted to cause loss of function and are not associated with chromosomal instability

CDC4/FBXW7 is part of a ubiquitin ligase complex which targets molecules such as cyclin E, c-myc, and c-jun for destruction. CDC4 mutations occur in several cancer types and are best described in colorectal tumors. Knockout of CDC4 in vitro in colorectal cancer cells causes changes suggestive of chromosomal instability (CIN). In p53(+/-) mice, radiation-induced lymphomas show deletion or mutation of one copy of CDC4 and knockdown of CDC4 leads to increased aneuploidy in mouse fibroblasts. We screened 244 colorectal tumors and 40 cell lines for CDC4 mutations and allelic loss. Six percent (18 of 284) of tumors, including near-diploid (CIN-) lesions, harbored CDC4 mutations and there was no association between mutation and CIN (polyploidy). The CDC4 mutation spectrum in colorectal tumors was heavily biased towards C:G > T:A changes, either missense mutations at critical arginine residues or nonsense changes in the 5' half of the gene. The reasons for this odd mutation spectrum were unclear but C:G > T:A changes were not found more often than expected at APC, K-ras, or p53 in the same tumors and we found no specific defects in DNA repair to account for the observations. No colorectal tumor was found to carry two CDC4 mutations predicted to abolish protein function; partial loss of CDC4 function may therefore cause tumorigenesis. The in vitro studies, therefore, did not assess the functional effects of mutant alleles which are found in vivo. CDC4 mutations may be selected primarily to drive progression through the cell cycle although CIN might be an important secondary effect in some cancers.

Examining the relationships between the Pro12Ala variant in PPARG and Type 2 diabetes-related traits in UK samples

AIMS

The Pro12Ala polymorphism in the PPARG gene alters amino acid sequence and has shown consistent association with susceptibility to Type 2 diabetes in several populations. The present study makes use of large, well-characterized case-control resources to enhance understanding of this susceptibility effect by examining related traits, such as body mass index (BMI), waist-hip ratio and age at diagnosis.

METHODS

The Pro12Ala variant was genotyped in two UK case samples, ascertained for positive family history and/or early onset of Type 2 diabetes (combined n=971); and in 1257 ethnically matched control subjects.

RESULTS

There were significant associations of the Pro12Ala single nucleotide polymorphism (SNP) genotypes with diabetes in both case-control comparisons (P=0.025 and P=0.039). Comparing individuals homozygous for the Pro allele, with those carrying an Ala allele, the combined odds ratio for diabetes was 1.40 (95% CIs, 1.12-1.76, P=0.0031). There was no association between the variant and either waist-hip ratio or age at diagnosis. Proline homozygosity was associated with increased BMI in one patient group (P=0.013) and decreased BMI in the other (P=0.038).

CONCLUSIONS

This study confirms that variation within PPARG influences susceptibility to Type 2 diabetes in UK samples. However, the relationship between PPARG variation and BMI is more complex, and studies in much larger sample sets will be required to more precisely characterize the effect of this variant on adiposity.

Refining molecular analysis in the pathways of colorectal carcinogenesis

BACKGROUND & AIMS

In the stepwise model, specific genetic and epigenetic changes accumulate as colorectal adenomas progress to carcinomas (CRCs). CRCs also acquire global phenotypes, particularly microsatellite instability (MSI) and aneuploidy/polyploidy (chromosomal instability, CIN). Few changes specific to MSI-low or CIN+ cancers have been established.

METHODS

We investigated 100 CRCs for: mutations and loss of heterozygosity (LOH) where appropriate, of APC, K-ras, BRAF, SMAD4, and p53; deletion on 5q around APC and 18q around SMAD4; total chromosomal-scale losses and gains; MSI; and CIN.

RESULTS

As expected, CIN- cancers had fewer chromosomal changes overall than CIN+ lesions, but after correcting for this, 5q deletions alone predicted CIN+ status. 5q deletions were not, however, significantly associated with APC mutations, which were equally frequent in CIN+ and CIN- tumors. We therefore found no evidence to show that mutant APC promotes CIN. p53 mutations/LOH were more common in CIN+ than CIN- lesions, and all chromosomal amplifications were in CIN+ tumors. CIN- cancers could be subdivided according to the total number of chromosomal-scale changes into CIN-low and CIN-stable groups; 18q deletion was the best predictor, being present in nearly all CIN-low lesions and almost no CIN-stable tumors. MSI-low was not associated with CIN, any specific mutation, a mutational signature, or clinicopathologic characteristic.

CONCLUSIONS

Overall, the components of the stepwise model (APC, K-ras, and p53 mutations, plus 18q LOH) tended to co-occur randomly. We propose an updated version of this model comprising 4 pathways of CRC pathogenesis, on the basis of 5q/18q deletions, MSI (high/low), and CIN (high/low/stable).

Large-scale studies of the association between variation at the TNF/LTA locus and susceptibility to type 2 diabetes

AIMS/HYPOTHESIS

The proinflammatory cytokine TNF-alpha has been implicated in the pathogenesis of insulin resistance and type 2 diabetes, and variation in the gene encoding TNF-alpha (TNF) has shown inconsistent associations with susceptibility to both conditions. Additionally, the coding non-synonymous variant T60N in the neighbouring LTA gene has been reported to be associated with type 2 diabetes. The present study aimed to obtain a robust assessment of the role of variation in the tightly linked TNF/LTA region in diabetes susceptibility by genotyping TNF and LTA variants in large case-control resources.

MATERIALS AND METHODS

The G-308A and G-238A TNF promoter variants and the LTA T60N polymorphism were genotyped in two UK case samples that were ascertained for positive family history and/or early onset of type 2 diabetes (combined n=858) and in 1,257 ethnically matched controls.

RESULTS

There were no significant associations between the T60N, G-308A or G-238A genotype and type 2 diabetes in the combined analysis (exact Cochran-Mantel-Haenszel statistic for ordered genotypes for T60N, p=0.69; for G-308A, p=0.51; for G-238A, p=0.16).

CONCLUSIONS/INTERPRETATION

The present study, one of the largest association analyses yet reported at this locus, provides no evidence that the specific TNF or LTA variants examined influence susceptibility to type 2 diabetes. More comprehensive studies of the TNF/LTA locus in substantially larger sample sets are required to establish whether genome sequence variation at this locus truly influences susceptibility to type 2 diabetes.

Chromosomal localization, genomic organization and evolution of the genes encoding human phosphatidylinositol transfer protein membrane-associated (PITPNM) 1, 2 and 3

Eukaryotic proteins containing a phosphatidylinositol transfer (PITP) domain can be divided into two groups, one consisting of small soluble 35-kDa proteins and the other those that are membrane-associated and show sequence similarities to the Drosophila retinal degeneration B (rdgB) protein. The rdgB protein consists of four domains, an amino terminal PITP domain, a Ca2+-binding domain, a transmembrane domain and a carboxyl terminal domain that interacts with the protein tyrosine kinase PYK2. Three mammalian phosphatidylinositol transfer protein membrane-associated genes (PITPNM1, 2 and 3) with homology to Drosophila rdgB have previously been described and shown to be expressed in the mammalian retina. These findings and the demonstration that the rdgB gene plays a critical role in the invertebrate phototransduction pathway have led to the mammalian genes being considered as candidate genes for human eye diseases. In order to facilitate the analysis of these genes we have used radiation hybrid mapping and fluorescence in situ hybridization to localize the PITPNM2 and 3 genes to human chromosomes 12p24 and 17p13 respectively and hybrid mapping to confirm the localization of PITPNM1 to chromosome 11q13. We have also determined the genomic organization of both the soluble and membrane-associated Drosophila and human PITP domain-containing genes. Phylogenetic analysis indicates that the two groups arose by gene duplication that occurred very early in animal evolution.

O(6)-methylguanine methyltransferase in colorectal cancers: detection of mutations, loss of expression, and weak association with G:C>A:T transitions

BACKGROUND AND AIMS

O(6)-methylguanine methyltransferase (MGMT) repairs inappropriately methylated guanine in DNA. MGMT mutations have not previously been reported in cancers, but in colorectal tumours MGMT promoter methylation is common and has been associated with increased G:C>A:T transitions, a high frequency of K-ras mutations, and low level microsatellite instability (MSI low). However, some have suggested that MGMT changes are background or secondary events, with little importance for tumorigenesis.

METHODS

We have analysed fresh frozen colorectal cancers and colorectal cancer cell lines for MGMT changes: mutations, allelic loss, and protein expression.

RESULTS

Six of 113 cancers harboured somatic missense MGMT mutations, at least three of which probably caused reduced MGMT function and were accompanied by silencing or loss of the wild-type allele. Cancers with pathogenic MGMT mutations tended to harbour G:C>A:T somatic mutations at other loci. Overall, MGMT expression was reduced or lost in more than half of the cancers. We found no association between MGMT expression and the somatic mutation spectrum at APC, beta-catenin, K-ras, or p53, but decreased MGMT expression was weakly associated with the presence of a G:C>A:T change at any one of these loci. Reduced MGMT expression was not however associated with an increased frequency of K-ras mutations or with MSI low.

CONCLUSION

In summary, we found that mutation of MGMT contributes to decreased protein function. Our findings provide good evidence to show that MGMT changes, including methylation, are selected rather than background events, at least in some cases. Decreased MGMT expression or function probably has a weak or moderate effect on the mutation spectrum in colorectal cancers.

Array comparative genomic hybridization analysis of colorectal cancer cell lines and primary carcinomas

Array comparative genomic hybridization, with a genome-wide resolution of approximately 1 Mb, has been used to investigate copy number changes in 48 colorectal cancer (CRC) cell lines and 37 primary CRCs. The samples were divided for analysis according to the type of genomic instability that they exhibit, microsatellite instability (MSI) or chromosomal instability (CIN). Consistent copy number changes were identified, including gain of chromosomes 20, 13, and 8q and smaller regions of amplification such as chromosome 17q11.2-q12. Loss of chromosome 18q was a recurrent finding along with deletion of discrete regions such as chromosome 4q34-q35. The overall pattern of copy number change was strikingly similar between cell lines and primary cancers with a few obvious exceptions such as loss of chromosome 6 and gain of chromosomes 15 and 12p in the former. A greater number of aberrations were detected in CIN+ than MSI+ samples as well as differences in the type and extent of change reported. For example, loss of chromosome 8p was a common event in CIN+ cell lines and cancers but was often found to be gained in MSI+ cancers. In addition, the target of amplification on chromosome 8q appeared to differ, with 8q24.21 amplified frequently in CIN+ samples but 8q24.3 amplification a common finding in MSI+ samples. A number of genes of interest are located within the frequently aberrated regions, which are likely to be of importance in the development and progression of CRC.

Genome-wide allelotyping of 104 Finnish colorectal cancers reveals an excess of allelic imbalance in chromosome 20q in familial cases

We have allelotyped a series of 104 Finnish colorectal cancers (CRCs) using 372 polymorphic markers spaced, on average, at 10 cM intervals, and have made a comparison of the differences in the frequency of allelic imbalance (AI) between familial and sporadic cases. Differences in the frequency of allelic imbalance (loss of heterozygosity or amplification) at a number of loci were detected and these were evaluated through analysis of additional series of cancers using specific markers. The most consistent difference was observed at chromosome 20q13.1-13.3 characterized by a two fold difference between familial and nonfamilial disease in a total of 99 familial and 186 sporadic Finnish cases. This difference was not observed in a UK set of 67 familial and 96 sporadic CRCs. The genome-wide effort resulted in a large data set giving clues to the location of putative CRC predisposition genes in the genome. The approach provides an alternative strategy for detecting cancer predisposition genes solely reliant on the molecular analysis of single cases obviating the requirement to collect multiple samples from families.

Does MSI-low exist?

Microsatellite instability is a well-recognised phenomenon. Ten to 15% of sporadic colorectal cancers with a high level of MSI form a well defined group with distinct clinicopathological features. The set of tumours with low level of microsatellite instability (MSI-low), though widely referred to, is not a clearly defined group. The definitions of MSI-low have varied among groups and between different studies from the same group. Some studies have found associations between the MSI-L phenotype and molecular features, notably a higher frequency of K-ras mutations, and, possibly, methylation of methylguanine methyltransferase. Two recent independent studies, however, showed respectively that 68% and 79%, non-MSI-H cancers showed some MSI and could therefore be classed nominally as MSI-L. There was no evidence for a qualitatively discrete MSI-L group, but quantitative differences in the level of MSI were found.

Low-level microsatellite instability occurs in most colorectal cancers and is a nonrandomly distributed quantitative trait

About 10-15% of colorectal cancers show high-level microsatellite instability. The characteristics and very existence of low-level instability (MSI-L) are unclear, although some studies have found associations between MSI-L and molecular characteristics, notably more frequent K-ras mutations and a low level of allele loss near APC. We have attempted to define a MSI-L group of tumors by analyzing 107 sporadic colorectal carcinomas at 44 microsatellites. Ten (9.7%) MSI-H cancers were identified, but there was no evidence for a discrete MSI-L group. However, the 97 non-MSI-H cancers showed greater variation in the frequency of MSI than was expected by chance. Most cancers (68%) in the non-MSI-H group showed some MSI and could therefore be classed as nominally MSI-L. No association was found between MSI-L (or the level of MSI) and any clinicopathological or molecular variable, including K-ras mutation and loss of heterozygosity at APC. The causes of variation in level of the MSI in non-MSI-H colorectal cancers are unknown, but the differences are quantitative and probably reflect the evolutionary histories of the cancers rather than qualitatively different genetic pathways of tumorigenesis.

A phase II study evaluating the tolerability and efficacy of CAELYX (liposomal doxorubicin, Doxil) in the treatment of unresectable pancreatic carcinoma

BACKGROUND

Preclinical studies of liposomal doxorubicin (CAELYX) have demonstrated significant inhibition of growth of human pancreatic cancer explants in nude mice. This study evaluated the efficacy of CAELYX in chemotherapy-naïve patients with unresectable, histologically confirmed pancreatic carcinoma. Secondary endpoints were quality of life (QOL). time to progression and overall survival.

PATIENTS AND METHODS

Twenty-two patients (median age 65) were enrolled. CAELYX was administered to the first five patients at a dose of 30 mg/m2 three-weekly. Two of these patients were dose escalated to 50 mg/m2 four-weekly. Subsequent patients were all treated on the latter schedule.

RESULTS

Two patients died after consenting to enter the study but before treatment was commenced and are not included in the analysis. Sixteen patients were evaluable for response. No objective responses were seen. Six patients had stable disease. One patient experienced grade 4 toxicity with palmar plantar dysaesthesia (PPE), but continued treatment after dose reduction and delay. Four patients experienced grade 3 stomatitis and two grade 3 nausea. Median survival from time of starting chemotherapy was 3.2 months (range 21 days to 19 months) and one year survival was 10%. Eight patients completed at least two EORTC QLQ C-30 questionnaires. There was no significant change in either global QOL or in any functional or symptom subscale score.

CONCLUSION

No objective responses were seen with CAELYX in this study. CAELYX was however associated with stable disease, but data were inconclusive with regard to clinical benefit. It warrants further investigation in the context of combination trials.

In patients with head injuries who undergo rapid sequence intubation using succinylcholine, does pretreatment with a competitive neuromuscular blocking agent improve outcome? A literature review

A literature search was undertaken for evidence of the effect of succinylcholine (SCH) on the intracranial pressure (ICP) of patients with acute brain injury and whether pretreatment with a defasciculating dose of competitive neuromuscular blocker is beneficial in this patient group. The authors could find no definitive evidence that SCH caused a rise in ICP in patients with brain injury. However, these studies were often weak and small. For those patients suffering acute traumatic brain injury the authors could find no studies that investigated the issue of pretreatment with defasciculating doses of competitive neuromuscular blockers and their effect on ICP in patients given SCH. There is level 2 evidence that SCH caused an increase in ICP for patients undergoing neurosurgery for brain tumours with elective anaesthesia and that pretreatment with defasciculating doses of neuromuscular blockers reduced such increases. It is unknown if this affects neurological outcome for this patient group.

SMAD4 mutations in colorectal cancer probably occur before chromosomal instability, but after divergence of the microsatellite instability pathway

Loss of chromosome 18q21 is well documented in colorectal cancer, and it has been suggested that this loss targets the DCC, DPC4/SMAD4, and SMAD2 genes. Recently, the importance of SMAD4, a downstream regulator in the TGF-beta signaling pathway, in colorectal cancer has been highlighted, although the frequency of SMAD4 mutations appears much lower than that of 18q21 loss. We set out to investigate allele loss, mutations, protein expression, and cytogenetics of chromosome 18 copy number in a collection of 44 colorectal cancer cell lines of known status with respect to microsatellite instability (MSI). Fourteen of thirty-two MSI(-) lines showed loss of SMAD4 protein expression; usually, one allele was lost and the other was mutated in one of a number of ways, including deletions of various sizes, splice site changes, and missense and nonsense point mutations (although no frameshifts). Of the 18 MSI(-) cancers with retained SMAD4 expression, four harbored missense mutations in the 3' part of the gene and showed allele loss. The remaining 14 MSI(-) lines had no detectable SMAD4 mutation, but all showed allele loss at SMAD4 and/or DCC. SMAD4 mutations can therefore account for about 50-60% of the 18q21 allele loss in colorectal cancer. No MSI(+) cancer showed loss of SMAD4 protein or SMAD4 mutation, and very few had allelic loss at SMAD4 or DCC, although many of these MSI(+) lines did carry TGFBIIR changes. Although SMAD4 mutations have been associated with late-stage or metastatic disease, our combined molecular and cytogenetic data best fit a model in which SMAD4 mutations occur before colorectal cancers become aneuploid/polyploid, but after the MSI(+) and MSI(-) pathways diverge. Thus, MSI(+) cancers may diverge first, followed by CIN(+) (chromosomal instability) cancers, leaving other cancers to follow a CIN(-)MSI(-) pathway.

CDX2 mutations do not account for juvenile polyposis or Peutz-Jeghers syndrome and occur infrequently in sporadic colorectal cancers

Peutz-Jeghers syndrome (PJS) and juvenile polyposis (JPS) are both characterized by the presence of hamartomatous polyps and increased risk of malignancy in the gastrointestinal tract. Mutations of the LKB1 and SMAD4 genes have been shown recently to cause a number of PJS and JPS cases respectively, but there remains considerable uncharacterized genetic heterogeneity in these syndromes, particularly JPS. The mouse homologue of CDX2 has been shown to give rise to a phenotype which includes hamartomatous-like polyps in the colon and is therefore a good candidate for JPS and PJS cases which are not accounted for by the SMAD4 and LKB1 genes. By analogy with SMAD4, CDX2 is also a candidate for somatic mutation in sporadic colorectal cancer. We have screened 37 JPS families/cases without known SMAD4 mutations, 10 Peutz-Jeghers cases without known LKB1 mutations and 49 sporadic colorectal cancers for mutations in CDX2. Although polymorphic variants and rare variants of unlikely significance were detected, no pathogenic CDX2 mutations were found in any case of JPS or PJS, or in any of the sporadic cancers.

Characterization of a novel human opsin gene with wide tissue expression and identification of embedded and flanking genes on chromosome 1q43

As part of an ongoing search to identify novel mammalian photopigments that may mediate nonvisual tasks such as circadian entrainment and acute suppression of pineal melatonin levels, a number of recently cloned nonvisual opsin sequences were used to search dbEST. panopsin (OPN3) was one of the clones identified using this approach. Expression analysis detects two transcripts of approximately 2.1 and 2.5 kb, in a wide range of tissues including brain, liver, and retina, which encode a predicted protein of 403 amino acids. The gene was localized to the region of chromosome 1q43 also encompassing the kynurenine monooxygenase (KMO) and choroideremia-like Rab escort protein 2 (CHML) genes. KMO and panopsin overlap at their 3' ends but are transcribed in opposite directions. CHML, an intronless gene, lies in intron 1 of panopsin.

Adjuvant mitozantrone chemotherapy in advanced prostate cancer

OBJECTIVE

To assess the role of mitozantrone, active in relapsed prostate cancer, as an adjuvant to hormonal treatment in patients with advanced prostate cancer.

PATIENTS AND METHODS

Between October 1990 and May 1995, 96 patients were entered into a stratified, randomized, single-institution study of hormonal therapy with a luteinizing hormone-releasing hormone agonist and flutamide, with or without four cycles of adjuvant mitozantrone. Of these, 93 patients were evaluable and the results were analysed in June 1999.

RESULTS

Patients with localized prostate cancer receiving adjuvant chemotherapy had a higher initial objective response rate (95% vs 53%, P = 0.008) and median survival (80 vs 36 months, P = 0.04) than patients who were treated with hormonal therapy alone. There was no advantage to adjuvant chemotherapy in patients with metastatic prostate cancer. There were insignificant advantages to chemotherapy in overall response rates (55% vs 39%, P = 0.3) and PSA responses (82% vs 64%, P = 0.11). There was no difference between the patient groups in time to treatment failure.

CONCLUSION

There was a survival advantage in using adjuvant mitozantrone in patients with locally advanced prostate cancer. Although the study comprised relative few patients, the follow-up period was long and the advantage significant. We recommend that the study be extended to include more patients.

Isolation and chromosomal localization of two human CDP-diacylglycerol synthase (CDS) genes

Phototransduction in Drosophila is a phosphoinositide-mediated signaling pathway. Phosphatidylinositol 4,5-bisphosphate (PIP2) plays a central role in this process, and its levels are tightly regulated. A photoreceptor-specific form of the enzyme CDP-diacylglycerol synthase (CDS), which catalyzes the formation of CDP-diacylglycerol from phosphatidic acid, is a key regulator of the amount of PIP2 available for signaling. cds mutants develop light-induced retinal degeneration. As part of a search for novel genes that may be involved in eye disease in human, using Drosophila phototransduction genes as a model system, two human CDP-diacylglycerol synthase genes (CDS1 and CDS2) were cloned and sequenced. Radiation hybrid panel mapping and fluorescence in situ hybridization were used to localize the genes to chromosomes 4q21 and 20p13. As yet, no known retinal diseases map to either of these regions.

Identification of a new human catenin gene family member (ARVCF) from the region deleted in velo-cardio-facial syndrome

Velo-cardio-facial syndrome (VCFS) and DiGeorge syndrome (DGS) are characterized by a wide spectrum of phenotypes, including conotruncal heart defects, cleft palate, and facial dysmorphology. Hemizygosity for a portion of chromosome 22q11 has been detected in 80-85% of VCFS/DGS patients. Both syndromes are thought to be the result of a developmental field defect. Using two independent gene-isolation procedures, we isolated a new catenin family member termed ARVCF (armadillo repeat gene deleted in VCFS) from the interval deleted in VCFS. ARVCF encodes a protein of 962 amino acids that contains a coiled coil domain and 10 tandem armadillo repeats. The primary structure of the protein is most closely related to the murine catenin p120CAS, which suggests a role for ARVCF in protein-protein interactions at adherens junctions. ARVCF is expressed ubiquitously in all fetal and adult tissues examined. This gene is hemizygous in all VCFS patients with interstitial deletions. Based on the physical location and potential functions of ARVCF, we suggest that hemizygosity at this locus may play a role in the etiology of some of the phenotypes associated with VCFS.