Individual- and trial-level surrogacy in colorectal cancer.

Two conditions must be fulfilled for an intermediate endpoint to be an acceptable surrogate for a true clinical endpoint: (1) there must be a strong association between the surrogate and the true endpoint, and (2) there must be a strong association between the effects of treatment on the surrogate and the true endpoint. We test whether these conditions are fulfilled for disease-free survival (DFS) and progression-free survival (PFS) on data from 20 clinical trials comparing experimental treatments with standard treatments for early and advanced colorectal cancer. The effects of treatment on DFS (or PFS in advanced disease) and OS were quantified through log hazard ratios (log HR), estimated through a Weibull model stratified for trial.

Ensuring trial validity by data quality assurance and diversification of monitoring methods.

Errors in the design, the conduct, the data collection process, and the analysis of a randomized trial have the potential to affect not only the safety of the patients in the trial, but also, through the introduction of bias, the safety of future patients. Trial monitoring, defined broadly to include methods of oversight which begin when the study is designed and continue until it is reported in a publication, has a role to play in eliminating such errors. On-site monitoring can be extremely inefficient for the identification of errors most likely to compromise patient safety or bias study results.

Exploring and validating surrogate endpoints in colorectal cancer.

Sargent et al (J Clin Oncol 23: 8664-8670, 2005) concluded that 3-year disease-free survival (DFS) can be considered a valid surrogate (replacement) endpoint for 5-year overall survival (OS) in clinical trials of adjuvant chemotherapy for colorectal cancer. We address the question whether the conclusion holds for trials involving other classes of treatments than those considered by Sargent et al. Additionally, we assess if the 3-year cutpoint is an optimal one.

Adjuvant chemotherapy with sequential or concurrent anthracycline and docetaxel: Breast International Group 02-98 randomized trial.

Background: Docetaxel is more effective than doxorubicin for patients with advanced breast cancer. The Breast International Group 02-98 randomized trial tested the effect of incorporating docetaxel into anthracycline-based adjuvant chemotherapy and compared sequential vs concurrent administration of doxorubicin and docetaxel.

Methods: Patients with lymph node-positive breast cancer (n = 2887) were randomly assigned to one of four treatments: 1) sequential control (four cycles of doxorubicin at 75 mg/m2, followed by three cycles of cyclophosphamide, methotrexate, and 5-fluorouracil [CMF]); 2) concurrent control (four cycles of doxorubicin at 60 mg/m2 plus cyclophosphamide at 600 mg/m2, followed by three cycles of CMF); 3) sequential docetaxel (three cycles of doxorubicin at 75 mg/m2, followed by three cycles of docetaxel at 100 mg/m2, followed by three cycles of CMF); 4) concurrent docetaxel (four cycles of doxorubicin at 50 mg/m2 plus docetaxel at 75 mg/m2, followed by three cycles of CMF).

Progression-free survival is a surrogate for survival in advanced colorectal cancer.

Purpose: The traditional end point for assessing efficacy of first-line chemotherapies for advanced cancer is overall survival (OS), but this end point requires prolonged follow-up and is potentially confounded by the effects of second-line therapies. We investigated whether progression-free survival (PFS) could be considered a valid surrogate for OS in advanced colorectal cancer.

Patients And Methods: Individual patient data were available from 10 historical trials comparing fluouracil (FU) + leucovorin with either FU alone (1,744 patients) or with raltitrexed (1,345 patients) and from three validation trials comparing FU + leucovorin with or without irinotecan or oxaliplatin (1,263 patients).

End points for colon cancer adjuvant trials: observations and recommendations based on individual patient data from 20,898 patients enrolled onto 18 randomized trials from the ACCENT Group.

Purpose: The traditional end point for colon adjuvant clinical trials is overall survival (OS). We previously validated disease-free survival (DFS) after 3-year follow-up as an excellent predictor of 5-year OS results. Here we explore shorter term DFS and OS end points, as well as stage dependency.

Phase III study comparing a semimonthly with a monthly regimen of fluorouracil and leucovorin as adjuvant treatment for stage II and III colon cancer patients: final results of GERCOR C96.1.

Purpose: This randomized, 2 x 2 factorial study compared a semimonthly regimen (fluorouracil [FU] and leucovorin [LV] semi-monthly is LV5FU2) with a monthly regimen of FU and LV (mFU/LV) as well as 24 weeks versus 36 weeks of each regimen as adjuvant treatment of stage II and III colon cancer.

Patients And Methods: LV5FU2 was administered semimonthly for 2 days as racemate (dl) or levogyre (l-; 200 or 100 mg/m(2)) as a 2-hour infusion, followed by 400 mg/m(2) FU bolus and a 600-mg/m(2) FU 22-hour continuous infusion. FU and LV were administered monthly (mFU/LV) for 5 days as dl- or l-LV 15-minute infusion, followed by a 400 mg/m(2) FU 15-minute infusion.

Reintroduction of oxaliplatin is associated with improved survival in advanced colorectal cancer.

Purpose: In the OPTIMOX1 trial, previously untreated patients with advanced colorectal cancer were randomly assigned to two different schedules of leucovorin, fluorouracil, and oxaliplatin that were administered until progression in the control arm or in a stop-and-go fashion in the experimental arm. The randomly assigned treatment groups did not differ significantly in terms of response rate, progression-free survival, and overall survival (OS). However, the impact of oxaliplatin reintroduction on OS was potentially masked by the fact that a large number of patients did not receive the planned oxaliplatin reintroduction or received oxaliplatin after second-line therapy in both treatment groups.

Long-term effect of leptin on H+-coupled peptide cotransporter 1 activity and expression in vivo: evidence in leptin-deficient mice.

The H+-coupled peptide cotransporter 1 (PepT1) mediates absorption of peptides and peptidomimetic drugs. Acute luminal leptin was reported to induce translocation of PepT1 to the enterocyte membrane in vitro and in vivo in the rat, resulting in enhanced peptide and peptidomimetic drug absorption. In this study, we analyzed chronic effects of leptin and leptin deficiency on PepT1 activity and expression in the small intestine.

Endpoints in adjuvant treatment trials: a systematic review of the literature in colon cancer and proposed definitions for future trials.

Disease-free survival is increasingly being used as the primary endpoint of most trials testing adjuvant treatments in cancer. Other frequently used endpoints include overall survival, recurrence-free survival, and time to recurrence. These endpoints are often defined differently in different trials in the same type of cancer, leading to a lack of comparability among trials.

Strong time dependence of the 76-gene prognostic signature for node-negative breast cancer patients in the TRANSBIG multicenter independent validation series.

Purpose: Recently, a 76-gene prognostic signature able to predict distant metastases in lymph node-negative (N(-)) breast cancer patients was reported. The aims of this study conducted by TRANSBIG were to independently validate these results and to compare the outcome with clinical risk assessment.

Experimental Design: Gene expression profiling of frozen samples from 198 N(-) systemically untreated patients was done at the Bordet Institute, blinded to clinical data and independent of Veridex.

Definition of clinically distinct molecular subtypes in estrogen receptor-positive breast carcinomas through genomic grade.

Purpose: A number of microarray studies have reported distinct molecular profiles of breast cancers (BC), such as basal-like, ErbB2-like, and two to three luminal-like subtypes. These were associated with different clinical outcomes. However, although the basal and the ErbB2 subtypes are repeatedly recognized, identification of estrogen receptor (ER) -positive subtypes has been inconsistent.

Inward translocation of the phospholipid analogue miltefosine across Caco-2 cell membranes exhibits characteristics of a carrier-mediated process.

Miltefosine (hexadecylphosphocholine, HePC) is the first effective oral agent for the treatment of visceral leishmaniasis. The characteristics of HePC incorporation into the human intestinal epithelial cell line Caco-2 were investigated in order to understand its oral absorption mechanism. The results provide evidence for the involvement of a carrier-mediated mechanism, since the association of HePC at the apical pole of Caco-2 cells was (1) saturable as a function of time with a rapid initial incorporation over 5 min followed by a more gradual increase; (2) saturable as a function of concentration over the range studied (2-200 microM) with a saturable component which followed Michaelis-Menten kinetics (apparent K (m) 15.

Regulation of the oligopeptide transporter, PEPT-1, in DSS-induced rat colitis.

The effect of colitis induced with dextran sodium sulfate (DSS) in rats on the bioavailability of drugs transported by the oligopeptide transporter PepT-1 was analyzed by studying the pharmacokinetics of PepT-1 substrates: cephalexin and valacyclovir, the prodrug of antiviral acyclovir. Western blot, immunohistochemistry, and real-time PCR were used to determine the PepT-1 protein and gene expression. We observed (1) no significant modification of PepT-1 expression in the duodenum and jejunum; (2) a slight decrease in both PepT-1 mRNA (50%) and protein expression (25%) in the ileum following DSS challenge; and (3) ectopic PepT-1 immunostaining in regenerative hyperplasia segments in the distal colon from DSS-treated rats where focal inflammation is localized.

Simulation studies of surrogate endpoint validation using single trial and multitrial statistical approaches.

Objective: A schema was recently proposed for assessing the levels of evidence for surrogate validity that included 4 domains: Target, Study Design, Statistical Strength, and Penalties. This report examines one component of the schema. It surveys the literature on methods of statistical validation of surrogate markers and compares these methods head-to-head using simulated datasets.

Definitions and validation criteria for biomarkers and surrogate endpoints: development and testing of a quantitative hierarchical levels of evidence schema.

Objective: There are clear advantages to using biomarkers and surrogate endpoints, but concerns about clinical and statistical validity and systematic methods to evaluate these aspects hinder their efficient application. Our objective was to review the literature on biomarkers and surrogates to develop a hierarchical schema that systematically evaluates and ranks the surrogacy status of biomarkers and surrogates; and to obtain feedback from stakeholders.

Methods: After a systematic search of Medline and Embase on biomarkers, surrogate (outcomes, endpoints, markers, indicators), intermediate endpoints, and leading indicators, a quantitative surrogate validation schema was developed and subsequently evaluated at a stakeholder workshop.

Intestinal absorption of miltefosine: contribution of passive paracellular transport.

Purpose: This study aimed to characterize the transepithelial transport of miltefosine (HePC), the first orally effective drug against visceral leishmaniasis, across the intestinal barrier to further understand its oral absorption mechanism.

Materials And Methods: Caco-2 cell monolayers were used as an in vitro model of the human intestinal barrier. The roles of active and passive mechanisms in HePC intestinal transport were investigated and the relative contributions of the transcellular and paracellular routes were estimated.

Hookworm infestation as a risk factor for Mooren's ulcer in South India.

Objective: To investigate the association between Mooren's ulcer and intestinal hookworm infestation in South India.

Design: Prospective observational case-control study.

Participants: Fifteen patients with Mooren's ulcer and 30 age- and gender-matched controls seen at Aravind Eye Hospital.

Surrogate threshold effect: an alternative measure for meta-analytic surrogate endpoint validation.

In many therapeutic areas, the identification and validation of surrogate endpoints is of prime interest to reduce the duration and/or size of clinical trials. Buyse et al. [Biostatistics 2000; 1:49-67] proposed a meta-analytic approach to the validation.

Impact of on-site initiation visits on patient recruitment and data quality in a randomized trial of adjuvant chemotherapy for breast cancer.

Purpose: To provide empirical evidence on the impact of on-site initiation visits on the following outcomes: patient recruitment, quantity and quality of data submitted to the trial coordinating office, and patients' follow-up time.

Patients And Methods: This methodological study was performed as part of a randomized trial comparing two combination chemotherapies for adjuvant treatment of breast cancer. Centers participating to the trial were randomized to either receive systematic on-site visits (Visited group), or not (Non-visited group).

Dose-dense adjuvant chemotherapy in node-positive breast cancer: docetaxel followed by epirubicin/cyclophosphamide (T/EC), or the reverse sequence (EC/T), every 2 weeks, versus docetaxel, epirubicin and cyclophosphamide (TEC) every 3 weeks. AERO B03 randomized phase II study.

Background: Adding a taxane to anthracycline-based adjuvant chemotherapy prolongs survival in node-positive patients but optimal dose and schedule remain undetermined. This study aimed to select a dose-dense regimen for further assessment in phase III studies.

Patients And Methods: Ninety-nine patients with node-positive invasive breast adenocarcinoma were randomly assigned to docetaxel (Taxotere) (T) 75 mg/m2, epirubicin (E) 75 mg/m2 and cyclophosphamide (C) 500 mg/m2 (TEC)x6, every 3 weeks; E 100 mg/m2, C 600 mg/m2 x 4, then T 100 mg/m2 x 4 (EC-->T) or the reverse sequence (T-->EC), every 2 weeks, with pegfilgrastim support.

Gene signature evaluation as a prognostic tool: challenges in the design of the MINDACT trial.

This Review describes the work conducted by the TRANSBIG consortium in the development of the MINDACT (Microarray In Node negative Disease may Avoid ChemoTherapy) trial. The goal of the trial is to provide definitive evidence regarding the clinical relevance of the 70-gene prognosis signature, and to assess the performance of this signature compared with that of traditional prognostic indicators for assigning adjuvant chemotherapy to patients with node-negative breast cancer. We outline the background work and the key questions in node-negative early-stage breast cancer, and then focus on the MINDACT trial design and statistical considerations.

Interaction between miltefosine and amphotericin B: consequences for their activities towards intestinal epithelial cells and Leishmania donovani promastigotes in vitro.

The aim of this study was to evaluate the potential of a combination of two antileishmanial drugs, miltefosine (HePC) and amphotericin B (AMB), when administered by the oral route. Caco-2 cell monolayers were used as a validated in vitro model of the intestinal barrier and Leishmania donovani promastigotes as a model for evaluating the effect of the drug combination. Spectroscopic measurements demonstrated that HePC and AMB associate, leading to the formation of mixed aggregates in which AMB is solubilized as monomers.