Comparison of error rates in single-arm versus randomized phase II cancer clinical trials

Zinc as a Mechanism-Based Strategy for Mitigation of Metals Toxicity

PURPOSE OF REVIEW

Zinc is an essential micronutrient with a myriad of key roles in human health. This review summarizes mechanistic data supporting the protective effects of zinc on metal toxicity and discusses the framework for an interventional clinical trial of zinc supplementation within a metal exposed Native American community.

RECENT FINDINGS

Many metals have common underlying mechanisms of toxicity that contribute to adverse human health effects. Studies demonstrate that multiple aspects of metal toxicity can be attributed to disruption of essential zinc-dependent functions. Multiple lines of evidence suggest that zinc may confer protection against metal toxicity in human populations with mixed-metal exposures. Thinking Zinc is a mechanism-informed intervention study of zinc supplementation to test the potential benefits of zinc while maintaining a culturally responsive research approach. The current knowledge of diverse metal and zinc interactions, coupled with strong mechanistic evidence for zinc benefits in the context of toxic metal exposures, supports the hypothesis that zinc supplementation may mitigate the impact of toxic metals exposures in populations with chronic mixed metal exposures and in populations with low zinc status.

Two-stage response adaptive randomization designs for multi-arm trials with binary outcome

In recent years, adaptive randomization methods have gained significant popularity in clinical research and trial design due to their ability to provide both efficiency and flexibility in adjusting the statistical procedures of ongoing clinical trials. For a study to compare multiple treatments, a multi-arm two-stage design could be utilized to select the best treatment from the first stage and further compare that treatment with control in the second stage. The traditional design used equal randomization in both stages. To better utilize the interim results from the first stage, we propose to develop response adaptive randomization two-stage designs for a multi-arm clinical trial with binary outcome. Two allocation methods are considered: (1) an optimal allocation based on a sequential design; (2) the play-the-winner rule. Optimal multi-arm two-stage designs are obtained under three criteria: minimizing the expected number of failures, minimizing the average expected sample size, and minimizing the expected sample size under the null hypothesis. Simulation studies show that the proposed adaptive design based on the play-the-winner rule has good performance. A phase II trial for patients with pancreas adenocarcinoma and a germline BRCA/ PALB2 mutation was used to illustrate the application of the proposed response adaptive randomization designs.

Andexanet alfa versus PCC products for factor Xa inhibitor bleeding: A systematic review with meta-analysis

Previous meta-analyses assessed andexanet alfa (AA) or prothrombin complex concentrate (PCC) products for the treatment of Factor Xa inhibitor (FXaI)-associated major bleeding. However, they did not include recent studies or assess the impact of the risk of bias. We conducted a systematic review with meta-analysis on the effectiveness of AA versus PCC products for FXaI-associated major bleeding, inclusive of the studies' risk of bias. PubMed and Embase were searched for comparative studies assessing major bleeding in patients using FXaI who received AA or PCC. We used the Methodological Index for NOn-Randomized Studies (MINORS) checklist and one question from the Joanna Briggs Institute (JBI) Critical Appraisal of Case Series tool to assess the risk of bias. Random-effects meta-analyses were performed to provide a pooled estimate for the effect of AA versus PCC products on hemostatic efficacy, in-hospital mortality, 30-day mortality, and thrombotic events. Low-moderate risk of bias studies were meta-analyzed separately, as well as combined with high risk of bias studies. Eighteen comparative evaluations of AA versus PCC were identified. Twenty-eight percent of the studies (n = 5) had low-moderate risk and 72% (n = 13) had a high risk of bias. Studies with low-moderate risk of bias suggested improvements in hemostatic efficacy [Odds Ratio (OR) 2.72 (95% Confidence Interval (CI): 1.15-6.44); one study], lower in-hospital mortality [OR 0.48 (95% CI: 0.38-0.61); three studies], and reduced 30-day mortality [OR 0.49 (95% CI: 0.30-0.80); two studies] when AA was used versus PCC products. When studies were included regardless of the risk of bias, pooled effects showed improvements in hemostatic efficacy [OR 1.36 (95% CI: 1.01-1.84); 12 studies] and reductions in 30-day mortality [OR 0.53 (95% CI: 0.37-0.76); six studies] for AA versus PCC. The difference in thrombotic events with AA versus PCC was not statistically significant in the low-moderate, high, or combined risk of bias groups. The evidence from low-moderate quality real-world studies suggests that AA is superior to PCC in enhancing hemostatic efficacy and reducing in-hospital and 30-day mortality. When studies are assessed regardless of the risk of bias, the pooled hemostatic efficacy and 30-day mortality risk remain significantly better with AA versus PCC.

Framework for the Use of External Controls to Evaluate Treatment Outcomes in Precision Oncology Trials

Advances in genomics have enabled anticancer therapies to be tailored to target specific genomic alterations. Single-arm trials (SATs), including those incorporated within umbrella, basket, and platform trials, are widely adopted when it is not feasible to conduct randomized controlled trials in rare biomarker-defined subpopulations. External controls (ECs), defined as control arm data derived outside the clinical trial, have gained renewed interest as a strategy to supplement evidence generated from SATs to allow comparative analysis. There are increasing examples demonstrating the application of EC in precision oncology trials. The prospective application of EC in conducting comparative studies is associated with distinct methodological challenges, the specific considerations for EC use in biomarker-defined subpopulations have not been adequately discussed, and a formal framework is yet to be established. In this review, we present a framework for conducting a prospective comparative analysis using EC. Key steps are (1) defining the purpose of using EC to address the study question, (2) determining if the external data are fit for purpose, (3) developing a transparent study protocol and a statistical analysis plan, and (iv) interpreting results and drawing conclusions on the basis of a prespecified hypothesis. We specify the considerations required for the biomarker-defined subpopulations, which include (1) specifying the comparator and biomarker status of the comparator group, (2) defining lines of treatment, (3) assessment of the biomarker testing panels used, and (4) assessment of cohort stratification in tumor-agnostic studies. We further discuss novel clinical trial designs and statistical techniques leveraging EC to propose future directions to advance evidence generation and facilitate drug development in precision oncology.

BASIC: A Bayesian adaptive synthetic-control design for phase II clinical trials

BACKGROUND

Randomized controlled trials are considered the gold standard for evaluating experimental treatments but often require large sample sizes. Single-arm trials require smaller sample sizes but are subject to bias when using historical control data for comparative inferences. This article presents a Bayesian adaptive synthetic-control design that exploits historical control data to create a hybrid of a single-arm trial and a randomized controlled trial.

METHODS

The Bayesian adaptive synthetic control design has two stages. In stage 1, a prespecified number of patients are enrolled in a single arm given the experimental treatment. Based on the stage 1 data, applying propensity score matching and Bayesian posterior prediction methods, the usefulness of the historical control data for identifying a pseudo sample of matched synthetic-control patients for making comparative inferences is evaluated. If a sufficient number of synthetic controls can be identified, the single-arm trial is continued. If not, the trial is switched to a randomized controlled trial. The performance of The Bayesian adaptive synthetic control design is evaluated by computer simulation.

RESULTS

The Bayesian adaptive synthetic control design achieves power and unbiasedness similar to a randomized controlled trial but on average requires a much smaller sample size, provided that the historical control data patients are sufficiently comparable to the trial patients so that a good number of matched controls can be identified in the historical control data. Compared to a single-arm trial, The Bayesian adaptive synthetic control design yields much higher power and much smaller bias.

CONCLUSION

The Bayesian adaptive synthetic-control design provides a useful tool for exploiting historical control data to improve the efficiency of single-arm phase II clinical trials, while addressing the problem of bias when comparing trial results to historical control data. The proposed design achieves power similar to a randomized controlled trial but may require a substantially smaller sample size.

Bayesian single-to-double arm transition design using both short-term and long-term endpoints

The choice between single-arm designs versus randomized double-arm designs has been contentiously debated in the literature of phase II oncology trials. Recently, as a compromise, the single-to-double arm transition design was proposed, combining the two designs into one trial over two stages. Successful implementation of the two-stage transition design requires a suspension period at the end of the first stage to collect the response data of the already enrolled patients. When the evaluation of the primary efficacy endpoint is overly long, the between-stage suspension period may unfavorably prolong the trial duration and cause a delay in treating future eligible patients. To accelerate the trial, we propose a Bayesian single-to-double arm design with short-term endpoints (BSDS), where an intermediate short-term endpoint is used for making early termination decisions at the end of the single-arm stage, followed by an evaluation of the long-term endpoint at the end of the subsequent double-arm stage. Bayesian posterior probabilities are used as the primary decision-making tool at the end of the trial. Design calibration steps are proposed for this Bayesian monitoring process to control the frequentist operating characteristics and minimize the expected sample size. Extensive simulation studies have demonstrated that our design has comparable power and average sample size but a much shorter trial duration than conventional single-to-double arm design. Applications of the design are illustrated using two phase II oncology trials with binary endpoints.

[89Zr]-immuno-PET prediction of response to rituximab treatment in patients with therapy refractory interstitial pneumonitis: a phase 2 trial

INTRODUCTION

Immune-mediated interstitial pneumonitis may be treated with anti-CD20 therapy after failure of conventional therapies. However, clinical response is variable. It was hypothesized that autoreactive CD20-positive cells may play an important role in this variability. This prospective study aims to elucidate if imaging of CD20-positive cells in the lungs allows prediction of the response to anti-CD20 treatment.

METHODS

Twenty-one patients with immune-mediated interstitial lung disease (ILD) with deteriorated pulmonary function received a dose of 1000 mg rituximab on day 1 and day 14 spiked with a tracer dose of radiolabeled [89Zr]-rituximab. PET/CT was performed on days 3 and 6. Standardized uptake values (SUV) were calculated as a measure for pulmonary CD20 expression. Based on pulmonary function tests (PFT), forced vital capacity (FVC), and diffusing capacity for carbon monoxide (DLCO), prior to and 6 months after treatment, patients were classified as responder (stable disease or improvement) or non-responder.

RESULTS

Fifteen patients (71%) were classified as responder. Pulmonary [89Zr]-rituximab PET SUVmean was significantly correlated with the change in FVC and DLCO (K = 0.49 and 0.56, respectively) when using target-to-background ratios, but not when using SUVmean alone. [89Zr]-rituximab SUVmean was significantly higher in responders than in non-responders (0.35 SD 0.09 vs. 0.23 SD 0.06; P = 0.02).

CONCLUSION

Rituximab treatment was effective in the majority of patients. As a higher pulmonary uptake of [89Zr]-rituximab correlated with improvement of PFT and treatment outcome, [89Zr]-rituximab PET imaging may serve as a potential predictive biomarker for anti-CD20 therapy.

TRIAL REGISTRATION

Clinicaltrials.gov identifier NCT02251964.

Current drug development and trial designs in neuro-oncology: report from the first American Society of Clinical Oncology and Society for Neuro-Oncology Clinical Trials Conference

Successful drug development for people with cancers of the CNS has been challenging. There are multiple barriers to successful drug development including biological factors, rarity of the disease, and ineffective use of clinical trials. Based upon a series of presentations at the First Central Nervous System Clinical Trials Conference hosted by the American Society of Clinical Oncology and the Society for Neuro-Oncology, we provide an overview on drug development and novel trial designs in neuro-oncology. This Review discusses the challenges of therapeutic development in neuro-oncology and proposes strategies to improve the drug discovery process by enriching the pipeline of promising therapies, optimising trial design, incorporating biomarkers, using external data, and maximising efficacy and reproducibility of clinical trials.

Feasibility of a Platform Trial Design for the Development of Mobile Health Applications: A Review

Background: A novel adaptive trial design called platform trials (PTs) may offer an effective, efficient, and unbiased approach to evaluate different developer versions of mobile health (m-health) apps. However, the feasibility of their use for this purpose is yet to be explored. Objective: This literature review aims to explore the reported challenges associated with the adaptive PT design to assess its feasibility for the development of m-health apps. Methods: A descriptive literature review using two databases (MEDLINE and Embase) was conducted. Documents published in English between 1947 and September 20, 2020, were eligible for inclusion. Results: The titles and abstracts of 758 records were screened after which 179 full-text articles were assessed for eligibility. A total of 41 articles were included in the synthesis, all published after the year 2000. The synthesis yielded eight distinct categories of challenging issues with PTs relevant to their application in m-health app development, along with potential solutions. These categories are ethical issues (e.g., related to informed consent, equipoise, justice) (with 19 articles contributing content), biases (7 articles), temporal drift (4 articles), miscellaneous statistical issues (3 articles), logistical issues (e.g., cost and human resources, frequent amendments; 6 articles), sample size and power conflict (2 articles), generalizability of the results (2 articles), and operational challenges (1 article). Conclusion: Although PT designs are relatively new, they have promising feasibility for the seamless evaluation of interventions that undergo continuous development, including m-health apps; however, various challenges may hinder their successful implementation.

A randomized Bayesian optimal phase II design with binary endpoint

In this paper, we propose a randomized Bayesian optimal phase II (RBOP2) design with a binary endpoint (e.g., response rate). A beta-binomial distribution is used to model the binary endpoint for a two-arm phase II trial. Posterior probabilities of the endpoint of interest are evaluated at each interim look and used in the decision to stop the trial due to futility. Compared with other Bayesian designs, the proposed RBOP2 design has the following merits: (i) strongly controls the type I error rate at a pre-defined level; (ii) optimizes the stopping boundaries, thus maximizing the power to detect treatment effects and minimizing the expected sample size for futile treatment; (iii) does not limit the number of interim looks, thus enabling frequent trial monitoring; and (iv) allows the stopping boundaries to be pre-defined in the protocol and is easy to implement. We conduct simulation studies to compare the proposed design with a group sequential design and other Bayesian randomized designs and evaluate its operating characteristics under different scenarios.

Evaluation of two-stage designs of Phase 2 single-arm trials in glioblastoma: a systematic review

BACKGROUND

Due to economical and ethical reasons, the two-stage designs have been widely used for Phase 2 single-arm trials in oncology because the designs allow us to stop the trial early if the proposed treatment is likely to be ineffective. Nonetheless, none has examined the usage for published articles that had applied the two-stage designs in Phase 2 single-arm trials in brain tumor. A complete systematic review and discussions for overcoming design issues might be important to better understand why oncology trials have shown low success rates in early phase trials.

METHODS

We systematically reviewed published single-arm two-stage Phase 2 trials for patients with glioblastoma and high-grade gliomas (including newly diagnosed or recurrent). We also sought to understand how these two-stage trials have been implemented and discussed potential design issues which we hope will be helpful for investigators who work with Phase 2 clinical trials in rare and high-risk cancer studies including Neuro-Oncology. The systematic review was performed based on the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA)-statement. Searches were conducted using the electronic database of PubMed, Google Scholar and ClinicalTrials.gov for potentially eligible publications from inception by two independent researchers up to May 26, 2022. The followings were key words for the literature search as index terms or free-text words: "phase II trials", "glioblastoma", and "two-stage design". We extracted disease type and setting, population, therapeutic drug, primary endpoint, input parameters and sample size results from two-stage designs, and historical control reference, and study termination status.

RESULTS

Among examined 29 trials, 12 trials (41%) appropriately provided key input parameters and sample size results from two-stage design implementation. Among appropriately implemented 12 trials, discouragingly only 3 trials (10%) explained the reference information of historical control rates. Most trials (90%) used Simon's two-stage designs. Only three studies have been completed for both stages and two out of the three completed studies had shown the efficacy.

CONCLUSIONS

Right implementation for two-stage design and sample size calculation, transparency of historical control and experimental rates, appropriate selection on primary endpoint, potential incorporation of adaptive designs, and utilization of Phase 0 paradigm might help overcoming the challenges on glioblastoma therapeutic trials in Phase 2 trials.

Study protocol of the TEC-ORL clinical trial: a randomized comparative phase II trial investigating the analgesic activity of capsaicin vs Laroxyl in head and neck Cancer survivors presenting with neuropathic pain sequelae

BACKGROUND

Neuropathic pain is common in cancer survivorship and is one of the most distressing symptoms for patients previously treated for head and neck cancer. Persistent neuropathic pain, when it is ongoing and uncontrolled, has a detrimental effect and erodes patients' quality of life. Patients treated for head and neck cancer are chronic opioid users to manage their post-treatment pain, which may entail an increased risk of addiction and overdose. We propose to evaluate the analgesic activity of high-concentration capsaicin patches for the treatment of head and neck cancer survivors presenting with neuropathic pain sequelae.

METHODS

TEC-ORL is a parallel, multicenter randomized comparative phase II study evaluating whether Capsaïcin patches (Qutenza®) reduce neuropathic pain when compared to Amitriptyline (Laroxyl®) in head and neck cancer survivors presenting with neuropathic pain sequelae. The primary efficacy outcome is the rate of patients with a pain reduction of at least two points at 9 months compared to baseline. Assuming that 5% of patients become lost to follow-up, 130 patients will need to be randomized to detect a 25% improvement (i.e., standard: 25%, experimental: 50%) using a one-sided chi-square test with an alpha of 0.05%. According to the recommendations for comparative phase II trials, the target differences and type I error rates are relaxed. Randomized patients will either be treated with a capsaicin 8% (Qutenza®) patch applied at three time intervals in the experimental arm or with Amitriptyline (Laroxyl®) (oral solution 40 mg/ml) taken for 9 months at the recommended daily dose of 25 mg to 75 mg in the control arm.

DISCUSSION

TEC-ORL is a randomized comparative phase II trial designed to comprehensively evaluate the analgesic activity of capsaicin compared to Laroxyl in Head and Neck Cancer survivors presenting with neuropathic pain sequelae.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT04704453 Date of registration: 2021/01/13.

Augmenting control arms with real-world data for cancer trials: Hybrid control arm methods and considerations

Background

Hybrid controlled trials with real-world data (RWD), where the control arm is composed of both trial and real-world patients, could facilitate research when the feasibility of randomized controlled trials (RCTs) is challenging and single-arm trials would provide insufficient information.

Methods

We propose a frequentist two-step borrowing method to construct hybrid control arms. We use parameters informed by a completed randomized trial in metastatic triple-negative breast cancer to simulate the operating characteristics of dynamic and static borrowing methods, highlighting key trade-offs and analytic decisions in the design of hybrid studies.

Results

Simulated data were generated under varying residual-bias assumptions (no bias: HR_RWD = 1) and experimental treatment effects (target trial scenario: HR_Exp = 0.78). Under the target scenario with no residual bias, all borrowing methods achieved the desired 88% power, an improvement over the reference model (74% power) that does not borrow information externally. The effective number of external events tended to decrease with higher bias between RWD and RCT (i.e. HR_RWD away from 1), and with weaker experimental treatment effects (i.e. HR_Exp closer to 1). All dynamic borrowing methods illustrated (but not the static power prior) cap the maximum Type 1 error over the residual-bias range considered. Our two-step model achieved comparable results for power, type 1 error, and effective number of external events borrowed compared to other borrowing methodologies.

Conclusion

By pairing high-quality external data with rigorous simulations, researchers have the potential to design hybrid controlled trials that better meet the needs of patients and drug development.

Early-phase clinical trial eligibility and response evaluation criteria for refractory, relapsed, or progressive neuroblastoma: A consensus statement from the National Cancer Institute Clinical Trials Planning Meeting

BACKGROUND

International standardized criteria for eligibility, evaluable disease sites, and disease response assessment in patients with refractory, progressive, or relapsed high-risk neuroblastoma enrolled in early-phase clinical trials are lacking.

METHODS

A National Cancer Institute-sponsored Clinical Trials Planning Meeting was convened to develop an international consensus to refine the tumor site eligibility criteria and evaluation of disease response for early-phase clinical trials in children with high-risk neuroblastoma.

RESULTS

Standardized data collection of patient and disease characteristics (including specified genomic data), eligibility criteria, a definition of evaluable disease, and response evaluations for primary and metastatic sites of disease were developed. Eligibility included two distinct patient groups: progressive disease and refractory disease. The refractory disease group was subdivided into responding persistent disease and stable persistent disease to better capture the clinical heterogeneity of refractory neuroblastoma. Requirements for defining disease evaluable for a response assessment were provided; they included requirements for biopsy to confirm viable neuroblastoma and/or ganglioneuroblastoma in those patients with soft tissue or bone disease not avid for iodine-123 meta-iodobenzylguanidine. Standardized evaluations for response components and time intervals for response evaluations were established.

CONCLUSIONS

The use of international consensus eligibility, evaluability, and response criteria for early-phase clinical studies will facilitate the collection of comparable data across international trials and promote more rapid identification of effective treatment regimens for high-risk neuroblastoma.

Novel Clinical Trial Designs in Neuro-Oncology

Scientific and technologic advances have led to a boon of candidate therapeutics for patients with malignancies of the central nervous system. The path from drug development to clinical use has generally followed a regimented order of sequential clinical trial phases. The recent increase in novel therapies, however, has strained the regulatory process and unearthed limitations of the current system, including significant cost, prolonged development time, and difficulties in testing therapies for rarer tumors. Novel clinical trial designs have emerged to increase efficiencies in clinical trial conduct to better evaluate and bring impactful drugs to patients in a timely manner. In order to better capture meaningful benefits for brain tumor patients, new endpoints to complement or replace traditional endpoints are also an increasingly important consideration. This review will explore the current challenges in the current clinical trial landscape and discuss novel clinical trial concepts, including consideration of limitations and risks of novel trial designs, within the context of neuro-oncology.

Glioblastoma Clinical Trials: Current Landscape and Opportunities for Improvement

Therapeutic advances for glioblastoma have been minimal over the past 2 decades. In light of the multitude of recent phase III trials that have failed to meet their primary endpoints following promising preclinical and early-phase programs, a Society for Neuro-Oncology Think Tank was held in November 2020 to prioritize areas for improvement in the conduct of glioblastoma clinical trials. Here, we review the literature, identify challenges related to clinical trial eligibility criteria and trial design in glioblastoma, and provide recommendations from the Think Tank. In addition, we provide a data-driven context with which to frame this discussion by analyzing key study design features of adult glioblastoma clinical trials listed on ClinicalTrials.gov as "recruiting" or "not yet recruiting" as of February 2021.

Lessons Learned from Phase II and Phase III Trials Investigating Therapeutic Agents for Cerebral Ischemia Associated with Aneurysmal Subarachnoid Hemorrhage

One of the challenges in bringing new therapeutic agents (since nimodipine) in for the treatment of cerebral ischemia associated with aneurysmal subarachnoid hemorrhage (aSAH) is the incongruence in therapeutic benefit observed between phase II and subsequent phase III clinical trials. Therefore, identifying areas for improvement in the methodology and interpretation of results is necessary to increase the value of phase II trials. We performed a systematic review of phase II trials that continued into phase III trials, evaluating a therapeutic agent for the treatment of cerebral ischemia associated with aSAH. We followed the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines for systematic reviews, and review was based on a peer-reviewed protocol (International Prospective Register of Systematic Reviews no. 222965). A total of nine phase III trials involving 7,088 patients were performed based on eight phase II trials involving 1558 patients. The following therapeutic agents were evaluated in the selected phase II and phase III trials: intravenous tirilazad, intravenous nicardipine, intravenous clazosentan, intravenous magnesium, oral statins, and intraventricular nimodipine. Shortcomings in several design elements of the phase II aSAH trials were identified that may explain the incongruence between phase II and phase III trial results. We suggest the consideration of the following strategies to improve phase II design: increased focus on the selection of surrogate markers of efficacy, selection of the optimal dose and timing of intervention, adjustment for exaggerated estimate of treatment effect in sample size calculations, use of prespecified go/no-go criteria using futility design, use of multicenter design, enrichment of the study population, use of concurrent control or placebo group, and use of innovative trial designs such as seamless phase II to III design. Modifying the design of phase II trials on the basis of lessons learned from previous phase II and phase III trial combinations is necessary to plan more effective phase III trials.

Design of placebo-controlled randomized trials of anticancer agents: Ethical considerations based on a review of published trials

BACKGROUND

Limited information exists about the design of placebo-controlled cancer trials. Through a systematic review of trials published in 2013, we describe placebo use in randomized trials testing anticancer agents and analyze strategies that increase exposure to the experimental regimen.

METHODS

Trials were classified as add-on (placebo in combination with standard treatment) or placebo-only. Strategies to allow more than half of the participants to receive the experimental regimen were reviewed. The risk-benefit ratio of receiving the experimental agent was considered favorable if the difference in primary outcome was significant (p ≤ 0.05), neutral if there was no significant difference in the primary outcome and the experimental agent did not add substantial toxicity, and unfavorable otherwise.

RESULTS

Eighty trials were included (32,694 participants). Most trials were add-on (69%). The risk-benefit outcome was favorable, neutral, and unfavorable to the experimental agent in 52%, 32%, and 16% of placebo-only trials and 25%, 53%, and 22%, respectively, of add-on trials. Four strategies increased exposure to the experimental regimen: one-way crossover (23%), uneven randomization (21%), three-arms (13%), and randomized discontinuation design (4%); these strategies were used more often in placebo-only trials.

CONCLUSION

A minority of participants received placebo alone and strategies to increase experimental exposure were used commonly. Fewer than half of the studies had favorable outcomes, thus defending the use of placebo controls, when there is no established treatment. Strategies that increase patient exposure to experimental agents rather than placebo may expose them to non-beneficial, sometimes toxic, experimental agents.

Leveraging external data in the design and analysis of clinical trials in neuro-oncology

Integration of external control data, with patient-level information, in clinical trials has the potential to accelerate the development of new treatments in neuro-oncology by contextualising single-arm studies and improving decision making (eg, early stopping decisions). Based on a series of presentations at the 2020 Clinical Trials Think Tank hosted by the Society of Neuro-Oncology, we provide an overview on the use of external control data representative of the standard of care in the design and analysis of clinical trials. High-quality patient-level records, rigorous methods, and validation analyses are necessary to effectively leverage external data. We review study designs, statistical methods, risks, and potential distortions in using external data from completed trials and real-world data, as well as data sources, data sharing models, ongoing work, and applications in glioblastoma.

Toward the Next Generation of High-Grade Glioma Clinical Trials in the Era of Precision Medicine

ABSTRACT

In the era of precision medicine, there is a desire to harness our improved understanding of genomic and molecular underpinnings of gliomas to develop therapies that can be tailored to individual patients and tumors. With the rapid development of novel therapies, there has been a growing need to develop smart clinical trials that are designed to efficiently test promising agents, identify therapies likely to benefit patients, and discard ineffective therapies. We review clinical trial design in gliomas and developments designed to address the unique challenges of precision medicine. To provide an overview of this topic, we examine considerations for endpoints and response assessment, biomarkers, and novel clinical trial designs such as adaptive platform trials in the testing of new therapies for glioma patients.

Meta-Analysis of Survival and Development of a Prognostic Nomogram for Malignant Pleural Mesothelioma Treated with Systemic Chemotherapy

(1) Purpose: Malignant pleural mesothelioma (MPM) is a rare cancer with an aggressive course. For patients who are medically inoperable or surgically unresectable, multi-agent systemic chemotherapy remains an accepted standard-of-care. The purpose of this meta-analysis is to provide baseline summative survival estimates as well as evaluate the influence of prognostic variables to provide comparative estimates for future trial designs. (2) Methods: Using PRISMA guidelines, a systematic review and meta-analysis was performed of MPM studies published from 2002-2019 obtained from the Medline database evaluating systemic therapy combinations for locally advanced or metastatic disease. Weighted random effects models were used to calculate survival estimates. The influence of proportions of known prognostic factors on overall survival (OS) were evaluated in the creation of a prognostic nomogram to estimate survival. The performance of this model was evaluated against data generated from one positive phase II study and two positive randomized trials. (3) Results: Twenty-four phase II studies and five phase III trials met the eligibility criteria; 2534 patients were treated on the included clinical studies. Ten trials included a platinum-pemetrexed-based treatment regimen, resulting in a pooled estimate of progression-free survival (PFS) of 6.7 months (95% CI: 6.2-7.2 months) and OS of 14.2 months (95% CI: 12.7-15.9 months). Fifteen experimental chemotherapy regimens have been tested in phase II or III studies, with a pooled median survival estimate of 13.5 months (95% CI: 12.6-14.6 months). Meta-regression analysis was used to estimate OS with platinum-pemetrexed using a variety of features, such as pathology (biphasic vs. epithelioid), disease extent (locally advanced vs. metastatic), ECOG performance status, age, and gender. The nomogram-predicted estimates and corresponding 95% CIs performed well when applied to recent randomized studies. (4) Conclusions: Given the rarity of MPM and the aggressive nature of the disease, innovative clinical trial designs with significantly greater randomization to experimental regimens can be performed using robust survival estimates from prior studies. This study provides baseline comparative values and also allows for accounting for differing proportions of known prognostic variables.

Summarising salient information on historical controls: A structured assessment of validity and comparability across studies

BACKGROUND

While placebo-controlled randomised controlled trials remain the standard way to evaluate drugs for efficacy, historical data are used extensively across the development cycle. This ranges from supplementing contemporary data to increase the power of trials to cross-trial comparisons in estimating comparative efficacy. In many cases, these approaches are performed without in-depth review of the context of data, which may lead to bias and incorrect conclusions.

METHODS

We discuss the original 'Pocock' criteria for the use of historical data and how the use of historical data has evolved over time. Based on these factors and personal experience, we created a series of questions that may be asked of historical data, prior to their use. Based on the answers to these questions, various statistical approaches are recommended. The strategy is illustrated with a case study in colorectal cancer.

RESULTS

A number of areas need to be considered with historical data, which we split into three categories: outcome measurement, study/patient characteristics (including setting and inclusion/exclusion criteria), and disease process/intervention effects. Each of these areas may introduce issues if not appropriately handled, while some may preclude the use of historical data entirely. We present a tool (in the form of a table) for highlighting any such issues. Application of the tool to a colorectal cancer data set demonstrates under what conditions historical data could be used and what the limitations of such an analysis would be.

CONCLUSION

Historical data can be a powerful tool to augment or compare with contemporary trial data, though caution is required. We present some of the issues that may be considered when involving historical data and what (if any) statistical approaches may account for differences between studies. We recommend that, where historical data are to be used in analyses, potential differences between studies are addressed explicitly.

Phase II, multi-center, open-label, single-arm clinical trial evaluating the efficacy and safety of Mycophenolate Mofetil in patients with high-grade locally advanced or metastatic osteosarcoma (ESMMO): rationale and design of the ESMMO trial

BACKGROUND

Clinical outcomes of patients with osteosarcoma remain unsatisfactory, with little improvement in a 5-year overall survival over the past three decades. There is a substantial need for further research and development to identify and develop more efficacious agents/regimens in order to improve clinical outcomes of patients for whom the prognosis is unfavorable. Recently, mycophenolate mofetil, a prodrug of mycophenolic acid, has been found to have anticancer activity against osteosarcoma in both in vitro and animal experiments, so that further investigation in humans is warranted.

METHODS

A total of 27 patients with high-grade locally advanced or metastatic osteosarcoma will be enrolled into this phase II, multi-center, open-label, single-arm, two-stage clinical trial. The main objectives of this study are to determine the efficacy and safety of mycophenolate mofetil in the patients. The primary endpoint is progression-free survival at 16 weeks; the secondary endpoints include progression-free survival, overall survival, overall response rate, safety parameters, pharmacokinetic parameters, biomarkers, pain score, and quality of life. Mycophenolate mofetil at the initial dose of 5 g/day or lower will be administered for 4 cycles (28 days/cycle) or until disease progression or unacceptable toxicity. The dose of mycophenolate mofetil may be reduced by 1-2 g/day or withheld for some Grade 3 or Grade 4 toxicities whenever clinically needed. The duration of study participation is approximately 4-5 months, with a minimum of 12 study visits. If mycophenolate mofetil proves beneficial to some patients, as evidenced by stable disease or partial response at 16 weeks, administration of mycophenolate mofetil will continue in the extension period.

DISCUSSION

This trial is the first step in the translation of therapeutic potential of mycophenolate mofetil emerging from in vitro and animal studies into the clinical domain. It is designed to assess the efficacy and safety of mycophenolate mofetil in patients with high-grade locally advanced or metastatic osteosarcoma. The results will provide important information about whether or not mycophenolate mofetil is worth further development.

TRIAL REGISTRATION

This trial was prospectively registered on Thai Clinical Trials Registry (registration number: TCTR20190701001). The posted information will be updated as needed to reflect protocol amendments and study progress.

Single-Arm Phase II Trials of Combination Therapies: A Review of the CTEP Experience 2008-2017

Designing and interpreting single-arm phase II trials of combinations of agents is challenging because it can be difficult, based on historical data, to identify levels of activity for which the combination would be worth pursuing. We identified Cancer Therapy Evaluation Program single-arm combination trials that were activated in 2008-2017 and tabulated their design characteristics and results. Positive trials were evaluated as to whether they provided credible evidence that the combination was better than its constituents. A total of 125 trials were identified, and 120 trials had results available. Twelve had designs where eligible patients were required to be resistant or refractory to all but one element of the combination. Only 17.8% of the 45 positive trials were deemed to provide credible evidence that the combination was better than its constituents. Of the 10 positive trials with observed rates 10 percentage points higher than their upper (alternative hypothesis) targets, only five were deemed to provide such credible evidence. Many trials were definitively negative, with observed clinical activity at or below their lower (null hypothesis) targets. Ideally, use of single-arm combination trials should be restricted to settings where each agent is known to have minimal monotherapy activity (and a randomized trial is infeasible). In these settings, an observed signal is attributable to synergy and thus could be used to decide whether the combination is worth pursuing. In other settings, credible evidence can still be obtained if the observed activity is much higher than expected, but experience suggests that this is a rare occurrence.

A Review of Perspectives on the Use of Randomization in Phase II Oncology Trials

Historically, phase II oncology trials assessed a treatment's efficacy by examining its tumor response rate in a single-arm trial. Then, approximately 25 years ago, certain statistical and pharmacological considerations ignited a debate around whether randomized designs should be used instead. Here, based on an extensive literature review, we review the arguments on either side of this debate. In particular, we describe the numerous factors that relate to the reliance of single-arm trials on historical control data and detail the trial scenarios in which there was general agreement on preferential utilization of single-arm or randomized design frameworks, such as the use of single-arm designs when investigating treatments for rare cancers. We then summarize the latest figures on phase II oncology trial design, contrasting current design choices against historical recommendations on best practice. Ultimately, we find several ways in which the design of recently completed phase II trials does not appear to align with said recommendations. For example, despite advice to the contrary, only 66.2% of the assessed trials that employed progression-free survival as a primary or coprimary outcome used a randomized comparative design. In addition, we identify that just 28.2% of the considered randomized comparative trials came to a positive conclusion as opposed to 72.7% of the single-arm trials. We conclude by describing a selection of important issues influencing contemporary design, framing this discourse in light of current trends in phase II, such as the increased use of biomarkers and recent interest in novel adaptive designs.

European Medicines Agency's Priority Medicines Scheme at 2 Years: An Evaluation of Clinical Studies Supporting Eligible Drugs

The Priority Medicines (PRIME) scheme was launched by the European Medicines Agency (EMA) in 2016 to expedite the development and approval of promising products targeting conditions with high unmet medical need. Manufacturers of PRIME drugs receive extensive regulatory advice on their trial designs. Until June 2018, the EMA granted PRIME status to 39 agents, evaluated in 138 studies (102 initiated before and 36 after PRIME eligibility). A third of the studies forming the basis of PRIME designation were randomized controlled trials, and a quarter of the studies were blinded. There was no statistically significant difference between trials initiated before and after PRIME designation in terms of randomized design and use of blinding. However, significantly more efficacy studies included a clinical end point after PRIME designation than before, and significantly fewer included surrogate measures alone. There were no statistically significant differences between the trial designs of PRIME and non-PRIME-designated products.

To randomize, or not to randomize, that is the question: using data from prior clinical trials to guide future designs

BACKGROUND

Understanding the value of randomization is critical in designing clinical trials. Here, we introduce a simple and interpretable quantitative method to compare randomized designs versus single-arm designs using indication-specific parameters derived from the literature. We demonstrate the approach through application to phase II trials in newly diagnosed glioblastoma (ndGBM).

METHODS

We abstracted data from prior ndGBM trials and derived relevant parameters to compare phase II randomized controlled trials (RCTs) and single-arm designs within a quantitative framework. Parameters included in our model were (i) the variability of the primary endpoint distributions across studies, (ii) potential for incorrectly specifying the single-arm trial's benchmark, and (iii) the hypothesized effect size. Strengths and weaknesses of RCT and single-arm designs were quantified by various metrics, including power and false positive error rates.

RESULTS

We applied our method to show that RCTs should be preferred to single-arm trials for evaluating overall survival in ndGBM patients based on parameters estimated from prior trials. More generally, for a given effect size, the utility of randomization compared with single-arm designs is highly dependent on (i) interstudy variability of the outcome distributions and (ii) potential errors in selecting standard of care efficacy estimates for single-arm studies.

CONCLUSIONS

A quantitative framework using historical data is useful in understanding the utility of randomization in designing prospective trials. For typical phase II ndGBM trials using overall survival as the primary endpoint, randomization should be preferred over single-arm designs.

Sample size computation in phase II designs combining the A'Hern design and the Sargent and Goldberg design

This work focuses on the modification of two classical phase II trials designs, the A'Hern design, a single-arm single-stage design, and the Sargent and Goldberg design introduced in the context of flexible screening designs. In the first part of the paper, we have proposed a drift-adjusted A'Hern design, a hybrid design combining the A'Hern design and the Sargent and Goldberg design. Indeed, classical single-arm phase II designs such as the A'Hern design are still widely used in oncology. Conducting randomized comparative phase II trials may be challenging in many settings due to the increased sample size and this despite larger type 1 errors. Randomized non-comparative phase II designs first introduced by Herson and Carter include a simultaneous randomized standard-treatment reference arm to detect any drift in the reference arm assumption, but the trial is analyzed against historical controls as if it were a single-arm study. However, not incorporating at all an internal control arm in the trial design has been criticized in the literature. Our new design takes into account the observed response rate in a non-comparative reference arm to reduce the trial's risk of a false-positive conclusion. In the second part, we have proposed an alternative strategy to determining the sample size of the screened selection design. The latter, introduced in recent years by Yap et al. and Wu et al., extended the Sargent and Goldberg design to include a comparison to a historical control. However, their sample size computations may have potential weaknesses, which motivated us to revisit the existing approaches. A detailed simulation study has been carried out to evaluate the operating characteristics of the drift-adjusted A'Hern design and the different sample size strategies of the screened selection designs.

Reduced-Intensity Conditioning with Fludarabine, Melphalan, and Total Body Irradiation for Allogeneic Hematopoietic Cell Transplantation: The Effect of Increasing Melphalan Dose on Underlying Disease and Toxicity

Disease relapse and toxicity are the shortcomings of reduced-intensity conditioning (RIC) for allogeneic hematopoietic cell transplantation (alloHCT). We hypothesized that adding total body irradiation (TBI) to and decreasing melphalan (Mel) from a base RIC regimen of fludarabine (Flu) and Mel would increase cytoreduction and improve disease control while decreasing toxicity. We performed a phase II trial of Flu 160 mg/m², Mel 50 mg/m², and TBI 400 cGy (FluMelTBI-50, n = 61), followed by a second phase II trial of Flu 160 mg/m², Mel 75 mg/m², and TBI 400cGy (FluMelTBI-75, n = 94) as RIC for alloHCT. Outcomes were compared with a contemporaneous cohort of 162 patients who received Flu 125 mg/m² and Mel 140 mg/m². Eligibility criteria were equivalent for all 3 regimens. All patients were ineligible for myeloablative/intensive conditioning. The median (range) follow-up for all patients was 51 (15 to 103) months. Day 100 donor lymphoid chimerism and transplant-related mortality, neutrophil and platelet engraftment, acute and chronic graft versus host disease incidence, overall survival (OS), and progression-free survival (PFS) were equivalent between FluMel, FluMelTBI-50, and FluMelTBI-75. Stomatitis wasdecreased for FluMelTBI versus FluMel (P < .01). PFS for patients not in complete remission on alloHCT was improved for FluMelTBI-75 versus FluMel (P = .03). On multivariate analysis, OS (P = .05) and PFS (P = .05) were significantly improved for FluMelTBI-75 versus FluMel. FluMelTBI-75 is better tolerated than FluMel, with improved survival and disease control.

Possible Causes of Failing to Meet Primary Endpoints: A Systematic Review of Randomized Controlled Phase 3 Clinical Trials in Patients With Non-Small Cell Lung Cancer

BACKGROUND

Non-small cell lung cancer (NSCLC) is the most common cause of cancer-related mortality worldwide and represents a huge unmet medical need. Despite the favorable results of phase 2 clinical trials, many phase 3 clinical trials fail to meet primary endpoints. Therefore, we investigated the causes of failure to meet primary endpoints in phase 3 clinical trials.

METHODS

We performed a systematic review of phase 3 clinical trials in patients with NSCLC. The results of phase 3 clinical trials collected from the survey were categorized as "negative" (failed to meet the primary endpoint) or "positive" (met the primary endpoint).

RESULTS

Of a total of 106 trials collected from this survey, 40 positive trials (38%) and 66 negative trials (62%) were identified. The majority of the primary endpoints were overall survival (OS) or progression-free survival (PFS) (94%). More trials using OS as the primary endpoint were negative (42 of 56 trials), and more trials using PFS as the primary endpoint were positive (24 of 44 trials). The median OS in the control arm in negative trials was significantly longer than the pretrial estimate ( P < .001), whereas the median PFS in the control arm in positive trials was relatively consistent with the pretrial estimate.

CONCLUSIONS

Our findings suggest that the selection of the primary endpoint and the pretrial estimate can potentially impact the results of phase 3 clinical trials in patients with NSCLC and are critical success factors when planning phase 3 clinical trials.

Quantifying local tumor morphological changes with Jacobian map for prediction of pathologic tumor response to chemo-radiotherapy in locally advanced esophageal cancer

We proposed a framework to detect and quantify local tumor morphological changes due to chemo-radiotherapy (CRT) using a Jacobian map and to extract quantitative radiomic features from the Jacobian map to predict the pathologic tumor response in locally advanced esophageal cancer patients. In 20 patients who underwent CRT, a multi-resolution BSpline deformable registration was performed to register the follow-up (post-CRT) CT to the baseline CT image. The Jacobian map (J) was computed as the determinant of the gradient of the deformation vector field. The Jacobian map measured the ratio of local tumor volume change where J  <  1 indicated tumor shrinkage and J  >  1 denoted expansion. The tumor was manually delineated and corresponding anatomical landmarks were generated on the baseline and follow-up images. Intensity, texture and geometry features were then extracted from the Jacobian map of the tumor to quantify tumor morphological changes. The importance of each Jacobian feature in predicting pathologic tumor response was evaluated by both univariate and multivariate analysis. We constructed a multivariate prediction model by using a support vector machine (SVM) classifier coupled with a least absolute shrinkage and selection operator (LASSO) for feature selection. The SVM-LASSO model was evaluated using ten-times repeated 10-fold cross-validation (10  ×  10-fold CV). After registration, the average target registration error was 4.30  ±  1.09 mm (LR:1.63 mm AP:1.59 mm SI:3.05 mm) indicating registration error was within two voxels and close to 4 mm slice thickness. Visually, the Jacobian map showed smoothly-varying local shrinkage and expansion regions in a tumor. Quantitatively, the average median Jacobian was 0.80  ±  0.10 and 1.05  ±  0.15 for responder and non-responder tumors, respectively. These indicated that on average responder tumors had 20% median volume shrinkage while non-responder tumors had 5% median volume expansion. In univariate analysis, the minimum Jacobian (p  =  0.009, AUC  =  0.98) and median Jacobian (p  =  0.004, AUC  =  0.95) were the most significant predictors. The SVM-LASSO model achieved the highest accuracy when these two features were selected (sensitivity  =  94.4%, specificity  =  91.8%, AUC  =  0.94). Novel features extracted from the Jacobian map quantified local tumor morphological changes using only baseline tumor contour without post-treatment tumor segmentation. The SVM-LASSO model using the median Jacobian and minimum Jacobian achieved high accuracy in predicting pathologic tumor response. The Jacobian map showed great potential for longitudinal evaluation of tumor response.

Clinical trial methodology in rare gynecologic tumor research: Strategies for success

BACKGROUND

Performing clinical trials in rare gynecologic cancers presents specific challenges. Strategies for improving accrual and modifications in clinical trial design are outlined.

METHODS

The literature was reviewed in order to present statistical designs pertinent to the study of rare gynecologic cancers. The experience of the Gynecologic Oncology Group/NRG Oncology is outlined as it relates to rare gynecologic cancer clinical trial development.

RESULTS

Significant progress has been made in studying rare tumors, both nationally and in gynecologic oncology, but challenges inherent to the study of uncommon diseases remain. Important components of these trials include establishing the standard of care, utilizing the appropriate clinical trial design to effectively answer the question in the trial, accurately estimating sample size, choosing modified and realistic endpoints, and avoiding pitfalls specific to rare tumors. Adaptive trial design and statistical modifications are important components of clinical trial design in rare tumors.

CONCLUSION

Strategies for effective study of rare gynecologic cancers must be implemented when designing clinical trials for these patients.

Phase 2 Neoadjuvant Treatment Intensification Trials in Rectal Cancer: A Systematic Review

PURPOSE

Multiple phase 2 trials of neoadjuvant treatment intensification in locally advanced rectal cancer have reported promising efficacy signals, but these have not translated into improved cancer outcomes in phase 3 trials. Improvements in phase 2 trial design are needed to reduce these false-positive signals. This systematic review evaluated the design of phase 2 trials of neoadjuvant long-course radiation or chemoradiation therapy treatment intensification in locally advanced rectal cancer.

METHODS AND MATERIALS

The PubMed, EMBASE, MEDLINE, and Cochrane Library databases were searched for published phase 2 trials of neoadjuvant treatment intensification from 2004 to 2016. Trial clinical design and outcomes were assessed, with statistical design and compliance rated using a previously published system. Multivariable meta-regression analysis of pathologic complete response (pCR) was conducted.

RESULTS

We identified 92 eligible trials. Patients with American Joint Committee on Cancer stage II and III equivalent disease were eligible in 87 trials (94.6%). In 43 trials (46.7%), local staging on magnetic resonance imaging was mandated. Only 12 trials (13.0%) were randomized, with 8 having a standard-treatment control arm. Just 51 trials (55.4%) described their statistical design, with 21 trials (22.8%) failing to report their sample size derivation. Most trials (n=84, 91.3%) defined a primary endpoint, but 15 different primary endpoints were used. All trials reported pCR rates. Only 38 trials (41.3%) adequately reported trial statistical design and compliance. Meta-analysis revealed a pooled pCR rate of 17.5% (95% confidence interval, 15.7%-19.4%) across treatment arms of neoadjuvant long-course radiation or chemoradiation therapy treatment intensification and substantial heterogeneity among the reported effect sizes (I² = 55.3%, P<.001). Multivariable meta-regression analysis suggested increased pCR rates with higher radiation therapy doses (adjusted P=.025).

CONCLUSIONS

Improvement in the design of future phase 2 rectal cancer trials is urgently required. A significant increase in randomized trials is essential to overcome selection bias and determine novel schedules suitable for phase 3 testing. This systematic review provides key recommendations to guide future treatment intensification trial design in rectal cancer.

Future prospects of therapeutic clinical trials in acute myeloid leukemia

Acute myeloid leukemia (AML) is a markedly heterogeneous hematological malignancy that is most commonly seen in elderly adults. The response to current therapies to AML is quite variable, and very few new drugs have been recently approved for use in AML. This review aims to discuss the issues with current trial design for AML therapies, including trial end points, patient enrollment, cost of drug discovery and patient heterogeneity. We also discuss the future directions in AML therapeutics, including intensification of conventional therapy and new drug delivery mechanisms; targeted agents, including epigenetic therapies, cell cycle regulators, hypomethylating agents and chimeric antigen receptor T-cell therapy; and detail of the possible agents that may be incorporated into the treatment of AML in the future.

Do single-arm trials have a role in drug development plans incorporating randomised trials?

Often, single-arm trials are used in phase II to gather the first evidence of an oncological drug's efficacy, with drug activity determined through tumour response using the RECIST criterion. Provided the null hypothesis of 'insufficient drug activity' is rejected, the next step could be a randomised two-arm trial. However, single-arm trials may provide a biased treatment effect because of patient selection, and thus, this development plan may not be an efficient use of resources. Therefore, we compare the performance of development plans consisting of single-arm trials followed by randomised two-arm trials with stand-alone single-stage or group sequential randomised two-arm trials. Through this, we are able to investigate the utility of single-arm trials and determine the most efficient drug development plans, setting our work in the context of a published single-arm non-small-cell lung cancer trial. Reference priors, reflecting the opinions of 'sceptical' and 'enthusiastic' investigators, are used to quantify and guide the suitability of single-arm trials in this setting. We observe that the explored development plans incorporating single-arm trials are often non-optimal. Moreover, even the most pessimistic reference priors have a considerable probability in favour of alternative plans. Analysis suggests expected sample size savings of up to 25% could have been made, and the issues associated with single-arm trials avoided, for the non-small-cell lung cancer treatment through direct progression to a group sequential randomised two-arm trial. Careful consideration should thus be given to the use of single-arm trials in oncological drug development when a randomised trial will follow.

Comparison of single-arm vs. randomized phase II clinical trials: a Bayesian approach

Single-arm studies are typically used in phase II of clinical trials, whose main objective is to determine whether a new treatment warrants further testing in a randomized phase III trial. The introduction of randomization in phase II, to avoid the limits of studies based on historical controls, is a critical issue widely debated in the recent literature. We use a Bayesian approach to compare single-arm and randomized studies, based on a binary response variable, in terms of their abilities of reaching the correct decision about the new treatment, both when it performs better than the standard one and when it is less effective. We evaluate how the historical control rate, the total sample size, and the elicitation of the prior distributions affect the decision about which study performs better.

Effectiveness of semen washing to prevent human immunodeficiency virus (HIV) transmission and assist pregnancy in HIV-discordant couples: a systematic review and meta-analysis

OBJECTIVE

To evaluate the effectiveness of semen washing in human immunodeficiency virus (HIV)-discordant couples in which the male partner is infected.

DESIGN

Systematic review and meta-analysis.

SETTING

Not applicable.

PATIENT(S)

Forty single-arm open-label studies among HIV-discordant couples that underwent intrauterine insemination (IUI) or in vitro fertilization (IVF) with or without intracytoplasmic sperm injection (ICSI) using washed semen.

INTERVENTION(S)

Semen washing followed by IUI, IVF, or IVF/ICSI.

MAIN OUTCOME MEASURE(S)

PRIMARY OUTCOME

HIV transmission to HIV-uninfected women; secondary outcomes: HIV transmission to newborns and proportion of couples achieving a clinical pregnancy.

RESULT(S)

No HIV transmission occurred in 11,585 cycles of assisted reproduction with the use of washed semen among 3,994 women. Among the subset of HIV-infected men without plasma viral suppression at the time of semen washing, no HIV seroconversions occurred among 1,023 women after 2,863 cycles of assisted reproduction with the use of washed semen. Studies that measured HIV transmission to infants reported no cases of vertical transmission. Overall, 56.3% of couples (2,357/4,184) achieved a clinical pregnancy with the use of washed semen.

CONCLUSION(S)

Semen washing appears to significantly reduce the risk of transmission in HIV-discordant couples desiring children, regardless of viral suppression in the male partner. There are no randomized controlled studies or studies from low-income countries, especially those with a large burden of HIV. Continued development of lower-cost semen washing and assisted reproduction technologies is needed. Integration of semen washing into HIV prevention interventions could help to further reduce the spread of HIV.

Clinical Utility of Metrics Based on Tumor Measurements in Phase II Trials to Predict Overall Survival Outcomes in Phase III Trials by Using Resampling Methods

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.

Correlation of single arm versus randomised phase 2 oncology trial characteristics with phase 3 outcome

BACKGROUND AND AIM

The primary aim of this study was to determine whether randomised phase 2 (RP2) trials predict phase 3 trial outcome better than single arm phase 2 (SAP2) studies. Although theoretical superiority of RP2 trials has been postulated, no empiric studies have been conducted.

METHODS

Published phase 3 trials testing systemic cancer therapy were identified through a Medline search. Those of superiority design, which cited phase 2 trials supporting the experimental arm, were included. Trial design and outcome details were extracted. Statistical analysis was performed using the Generalized Estimating Equation method correlating phase 2 features with phase 3 outcome, accounting for any phase 3 duplication.

RESULTS

Of 189 eligible phase 3 trials, 18.5% were in haematological malignancies and 81.5% in solid tumors. The primary outcome was positive in 79 (41.8%). These were supported by 336 phase 2 trials (range 1-9 per phase 3 trial) including 66 RP2 trials. Positive phase 2 outcome, randomised or not, correlated with positive phase 3 outcome (p=0.03). RP2 studies were not superior to SAP2 studies at predicting phase 3 study success. Phase 2 trial features not predictive of phase 3 outcome included primary endpoint, sponsorship, sample size, similarity in patient population and therapy.

CONCLUSIONS

RP2 studies were not superior to SAP2 trials at predicting phase 3 study success. Further research into phase 2 trial design is required given the added resources required to conduct RP2 studies and the lack of empiric evidence supporting superiority over single arm studies.