Mandrekar, Sumithra J.

Purpose Phase II clinical trials inform go/no-go decisions for proceeding to phase III trials, and appropriate end points in phase II trials are critical for facilitating this decision. Phase II solid tumor trials have traditionally used end points such as tumor response defined by Response Evaluation Criteria for Solid Tumors (RECIST). We previously reported that absolute and relative changes in tumor measurements demonstrated potential, but not convincing, improvement over RECIST to predict overall survival (OS). We have evaluated the metrics by using additional measures of clinical utility and data from phase III trials. Methods Resampling methods were used to assess the clinical utility of metrics to predict phase III outcomes from simulated phase II trials. In all, 2,000 phase II trials were simulated from four actual phase III trials (two positive for OS and two negative for OS). Cox models for three metrics landmarked at 12 weeks and adjusted for baseline tumor burden were fit for each phase II trial: absolute changes, relative changes, and RECIST. Clinical utility was assessed by positive predictive value and negative predictive value, that is, the probability of a positive or negative phase II trial predicting an effective or ineffective phase III conclusion, by prediction error, and by concordance index (c-index). Results Absolute and relative change metrics had higher positive predictive value and negative predictive value than RECIST in five of six treatment comparisons and lower prediction error curves in all six. However, differences were negligible. No statistically significant difference in c-index across metrics was found. Conclusion The absolute and relative change metrics are not meaningfully better than RECIST in predicting OS.

Clinical trial design strategies have evolved over the past few years as a means to accelerate the drug development process so that the right therapies can be delivered to the right patients. Basket, umbrella, and adaptive enrichment strategies represent a class of novel designs for testing targeted therapeutics in oncology. Umbrella trials include a central infrastructure for screening and identification of patients, and focus on a single tumor type or histology with multiple subtrials, each testing a targeted therapy within a molecularly defined subset. Basket trial designs offer the possibility to include multiple molecularly defined subpopulations, often across histology or tumor types, but included in one cohesive design to evaluate the targeted therapy in question. Adaptive enrichment designs offer the potential to enrich for patients with a particular molecular feature that is predictive of benefit for the test treatment based on accumulating evidence from the trial. This review will aim to discuss the fundamentals of these design strategies, the underlying statistical framework, the logistical barriers of implementation, and, ultimately, the interpretation of the trial results. New statistical approaches, extensive multidisciplinary collaboration, and state of the art data capture technologies are needed to implement these strategies in practice. Logistical challenges to implementation arising from centralized assay testing, requirement of multiple specimens, multidisciplinary collaboration, and infrastructure requirements will also be discussed. This review will present these concepts in the context of the National Cancer Institute's precision medicine initiative trials: MATCH, ALCHEMIST, Lung MAP, as well as other trials such as FOCUS4.

Background. A phase II design with an option for direct assignment (stop randomization and assign all patients to experimental treatment based on interim analysis, IA) for a predefined subgroup was previously proposed. Here, we illustrate the modularity of the direct assignment option by applying it to the setting of two predefined subgroups and testing for separate subgroup main effects.Methods. We power the 2-subgroup direct assignment option design with 1 IA (DAD-1) to test for separate subgroup main effects, with assessment of power to detect an interaction in a post-hoc test. Simulations assessed the statistical properties of this design compared to the 2-subgroup balanced randomized design with 1 IA, BRD-1. Different response rates for treatment/control in subgroup 1 (0.4/0.2) and in subgroup 2 (0.1/0.2, 0.4/0.2) were considered.Results. The 2-subgroup DAD-1 preserves power and type I error rate compared to the 2-subgroup BRD-1, while exhibiting reasonable power in a post-hoc test for interaction.Conclusion. The direct assignment option is a flexible design component that can be incorporated into broader design frameworks, while maintaining desirable statistical properties, clinical appeal, and logistical simplicity.

Purpose A major concern with sublobar resection (SR) for non–small-cell lung cancer (NSCLC) is high local recurrence (LR). Adjuvant brachytherapy may reduce LR This multicenter randomized trial compares SR to SR with brachytherapy (SRB). Patients and Methods High-risk operable patients with NSCLC ≤ 3 cm were randomly assigned to SR or SRB. The primary end point was time to LR, where LR included recurrence at the staple line (local progression), in the primary tumor lobe away from the staple line, and in ipsilateral hilar nodes. The trial was designed to have a 90% power to detect a hazard ratio (HR) of 0.315 in favor of SRB, using a one-sided type I error rate of 0.05 with a sample size of 100 eligible patients in each arm. Results Two hundred twenty-four patients were randomly assigned; 222 patients were evaluable for intent-to-treat analysis. Median age was 71 years (range, 49 to 87 years). No differences were found in baseline characteristics. Median follow-up time was 4.38 years (range, 0.04 to 5.59 years). There was no difference in time to LR (HR, 1.01; 95% CI, 0.51 to 1.98; log-rank P = .98) or in the types of LR. Local progression occurred in only 17 (7.7%) of 222 patients. In patients with potentially compromised margins (margin < 1 cm, margin-to-tumor ratio < 1, positive staple line cytology, wedge resection, nodule size > 2.0 cm), SRB did not reduce LR, although trends favored the SRB arm. This was most marked in 14 patients with positive staple line cytology (HR, 0.22; P = .24). Three-year overall survival rates were similar for patients in the SR (71%) and SRB (71%) arms (P = .97). Conclusion Brachytherapy did not reduce LR after SR. This finding may have been related to closer attention to parenchymal margins by surgeons participating in this study.

The primary goal of phase I dose-finding trials has been historically to understand the safety profile of a new treatment/regimen and establish the maximum tolerated dose (MTD) for further investigation in a specific tumor type. These designs hinged on the assumption that the highest safe dose is also likely to be the most efficacious dose. In the current era of stratified medicine and targeted therapies, these assumptions and designs are quickly becoming obsolete. Newer approaches to dose-finding designs are emerging with a focus on not just safety, but also an efficacy (clinical- or biomarker-based) measure to guide the determination of the “optimal” dose (not necessarily the MTD) model, as opposed to rule-based designs. These designs allow for flexibility in trial conduct, with improved precision in estimating the dose to take forward for further testing, patient selection/enrichment strategies to maximize the chance of therapeutic effect, and expansion cohorts to further understand the safety/efficacy of the agent and patient subsets most likely to benefit from the agent under investigation. Although advances in technology have enabled the possibility of using these newer approaches, the acceptance and integration of these approaches in practice can only be accelerated if it is developed in concert with a clinical paradigm.

Purpose We sought to test and validate the predictive utility of trichotomous tumor response (TriTR; complete response [CR] or partial response [PR] v stable disease [SD] v progressive disease [PD]), disease control rate (DCR; CR/PR/SD v PD), and dichotomous tumor response (DiTR; CR/PR v others) metrics using alternate cut points for PR and PD. The data warehouse assembled to guide the Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 was used. Methods Data from 13 trials (5,480 patients with metastatic breast cancer, non–small-cell lung cancer, or colorectal cancer) were randomly split (60:40) into training and validation data sets. In all, 27 pairs of cut points for PR and PD were considered: PR (10% to 50% decrease by 5% increments) and PD (10% to 20% increase by 5% increments), for which 30% and 20% correspond to the RECIST categorization. Cox proportional hazards models with landmark analyses at 12 and 24 weeks stratified by study and number of lesions (fewer than three v three or more) and adjusted for average baseline tumor size were used to assess the impact of each metric on overall survival (OS). Model discrimination was assessed by using the concordance index (c-index). Results Standard RECIST cut points demonstrated predictive ability similar to the alternate PR and PD cut points. Regardless of tumor type, the TriTR, DiTR, and DCR metrics had similar predictive performance. The 24-week metrics (albeit with higher c-index point estimate) were not meaningfully better than the 12-week metrics. None of the metrics did particularly well for breast cancer. Conclusion Alternative cut points to RECIST standards provided no meaningful improvement in OS prediction. Metrics assessed at 12 weeks have good predictive performance.

Abstract Background: In patients with Barrett's esophagus, chronic reflux injury and inflammation are associated with esophageal adenocarcinoma, one of the most rapidly increasing lethal cancers. Epidemiological and preclinical studies support decreased risk of esophageal adenocarcinoma with NSAID use. Gastroesophageal refluxate contents can promote carcinogenesis in Barrett's metaplasia by activating AKT, which up regulates COX-2 expression and prostaglandin biosynthesis. We recently noted that neoplastic transformation in Barrett's esophagus is associated with increased AKT expression, particularly isoform AKT1. The AIM of this study is to investigate the effect of NSAID (Aspirin) use in patients with Barrett's esophagus on AKT1 expression using frozen tissue from the randomized, phase II trial of aspirin and esomeprazole for esophageal cancer chemoprevention in Barrett's esophagus patients and to assess the functional consequences of AKT1 expression in-vitro. Methods and Results: In a subset of patients (12 of 120 patients) with Barrett's esophagus who were randomized to placebo, lower dose (81 mg) or higher dose (325 mg) Aspirin for 4 weeks, both PCR and Western blot revealed marked reduction in AKT1 expression in patients who received 325 mg of Aspirin daily compared to patients who received placebo. Our in-vitro experiments support that AKT1 expression is functionally relevant to the process of carcinogenesis in Barrett's epithelial cells. Using adenovirus to induce AKT1 expression, we show that increased AKT1 expression increases Barrett's epithelial cell growth, facilitates RAS-mediated transformation of pre-neoplastic epithelial cells and promotes colony formation. Since AKT1 is known as Warburg kinase and regulates cellular glucose uptake to support aerobic glycolysis during growth de-regulation and neoplasia, we examined the uptake of fluorescent deoxyglucose analog (2-NBDG) in Barrett's epithelial cells transduced with AKT1 adenovirus. At 48 hrs, compared to control, AKT1 overexpression resulted in increased glucose uptake both by metaplastic and neoplastic Barrett's epithelial cells. Transcriptional repression of AKT1 abrogated the 2-NBDG uptake by these cells. Finally, we did pathway specific qPCRs and noted that use of Aspirin is associated with altered expression of chromatin remodelers that could down-regulate AKT1 expression. Conclusion: Collectively, our results demonstrate that Aspirin mediated down-regulation of Warburg kinase AKT1 in patients with Barrett?s esophagus is a novel mechanism for the regulation of Barrett?s epithelial cell growth. The in-depth characterization of molecular mechanisms is currently underway. This abstract is also presented as Poster A82. Citation Format: Navtej S. Buttar, Gary W. Falk, Cathrine J. DeMars, Sonia Chowdhury, Ahmed Elebiary, Anamay Sharma, Sidhartha Chaudhry, Nathan R. Foster, Katie L. Allen Ziegler, Yvonne Romero, Norman E. Marcon, Thomas Schnell, Douglas A. Corley, Prateek Sharma, Marcia R. Cruz-Correa, Chin Hur, David E. Fleischer, Amitabh Chak, Kenneth R. DeVault, David S. Weinberg, Gary Della’Zanna, Ellen Richmond, Thomas C. Smyrk, Sumithra Mandrekar, Paul J. Limburg. Aspirin mediated downregulation of Warburg kinase AKT1 in patients with Barrett's esophagus: Implications in neoplastic transformation. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr PR-03.