Meta-Analysis of 49 Roche Oncology Trials Comparing Blinded Independent Central Review (BICR) and Local Evaluation to Assess the Value of BICR

BACKGROUND

Blinded independent central review (BICR) of radiographic images is frequently conducted in oncology trials to address the potential bias of local evaluation (LE) of endpoints such as progression-free survival (PFS) and objective response rate (ORR). Given that BICR is a complex and costly process, we evaluated the agreement between LE- and BICR-based treatment effect results and the impact of BICR on regulatory decision-making.

MATERIALS AND METHODS

Meta-analyses were performed using hazard ratios (HRs) for PFS and odds ratios (ORs) for ORR from all randomized Roche-supported oncology clinical trials during 2006-2020 that had both LE and BICR results (49 studies with a total of over 32 000 patients).

RESULTS

Overall, the evaluation bias of LE overestimating the treatment effect compared with BICR based on PFS was numerically small and not clinically meaningful, especially for double-blind studies (HR ratio between BICR and LE: 1.044). A larger bias is more likely to occur in studies with open-label design, smaller sample sizes, or an unequal randomization ratio. The majority (87%) of the PFS comparisons led to the same statistical inference by BICR and LE. For ORR, a high degree of agreement between BICR and LE results was also observed (OR ratio of 1.065), although the agreement was slightly lower than for PFS.

CONCLUSION

BICR did not notably impact the study interpretation nor drive the sponsor's regulatory submission decisions. Hence, if bias can be diminished by appropriate means, LE is deemed as reliable as BICR for certain study settings.

Improvement of assessment in surrogate endpoint and safety outcome of single-arm trials for anticancer drugs

INTRODUCTION

Single-arm trials (SATs) and surrogate endpoints were adopted as pivotal evidence for accelerated approval of anticancer drugs for more than 30 years. However, concerns regarding clinical evidence quality in trials, particularly in the SATs of anticancer drugs have increasingly been raised. SAT may not always provide strong evidence due to the lack of control and endpoint of overall survival that is typically present in randomized controlled trials.

AREAS COVERED

Clinical trial endpoint adjudication is a crucial factor in surrogate outcome measurement to ensure the data quality of the clinical trial of anticancer drugs. In this review, we systematically discuss the characteristics of adjudications in assessments in surrogate endpoint and safety outcome respectively, which are essential for ensuring reliable and transparent outcomes. Endpoint adjudication effectively reduces potential bias and mitigates variance that may be introduced by investigators when analyzing the medical records for the surrogate endpoints. We analyze the advantages and disadvantages of each type of adjudicator and provide a summary of the roles of adjudicators.

EXPERT OPINION

By suggestion of improving data reliability and transparency in pivotal trials, this review aims to supply a strategy for better clinical investigation for anticancer drugs, ultimately leading to better patient outcomes.

The ever-expanding landscape of antibody-drug conjugates (ADCs) in solid tumors: A systematic review

BACKGROUND

The advent of targeted therapies signaled novel avenues for more optimal oncological outcomes. Antibody-drug conjugates (ADCs) have risen as a cornerstone of the ever-expanding targeted therapy era. The purpose of this systematic review is to delineate the rapidly evolving clinical landscape of ADCs for solid tumors.

METHODS

A literature search was performed in Medline, Embase and Cochrane databases for phase II and III clinical trials. Outcomes of interest were the objective response rate, overall survival, progression-free survival and adverse events.

RESULTS

A total of 92 clinical trials (76 phase II and 16 phase III) evaluated the efficacy and safety of ADCs for a plethora of solid tumors. Out of the 30 investigated ADCs, 8 have received approval by regulatory organizations for solid tumors. Currently, 52 phase III clinical trials for ADCs are ongoing.

CONCLUSION

ADCs have shown promising results for several solid tumors and various cancer settings.

Optimizing disease progression assessment using blinded central independent review and comparing it with investigator assessment in the PRIMA/ENGOT-ov26/GOG-3012 trial: challenges and solutions

OBJECTIVE

Progression-free survival is an established clinically meaningful endpoint in ovarian cancer trials, but it may be susceptible to bias; therefore, blinded independent centralized radiological review is often included in trial designs. We compared blinded independent centralized review and investigator-assessed progressive disease performance in the PRIMA/ENGOT-ov26/GOG-3012 trial examining niraparib monotherapy.

METHODS

PRIMA/ENGOT-ov26/GOG-3012 was a randomized, double-blind phase 3 trial; patients with newly diagnosed stage III/IV ovarian cancer received niraparib or placebo. The primary endpoint was progression-free survival (per Response Evaluation Criteria in Solid Tumors [RECIST] v1.1), determined by two independent radiologists, an arbiter if required, and by blinded central clinician review. Discordance rates between blinded independent centralized review and investigator assessment of progressive disease and non-progressive disease were routinely assessed. To optimize disease assessment, a training intervention was developed for blinded independent centralized radiological reviewers, and RECIST refresher training was provided for investigators. Discordance rates were determined post-intervention.

RESULTS

There was a 39% discordance rate between blinded independent centralized review and investigator-assessed progressive disease/non-progressive disease in an initial patient subset (n=80); peritoneal carcinomatosis was the most common source of discordance. All reviewers underwent training, and as a result, changes were implemented, including removal of two original reviewers and identification of 10 best practices for reading imaging data. Post-hoc analysis indicated final discordance rates between blinded independent centralized review and investigator improved to 12% in the overall population. Median progression-free survival and hazard ratios were similar between blinded independent centralized review and investigators in the overall population and across subgroups.

CONCLUSION

PRIMA/ENGOT-ov26/GOG-3012 highlights the need to optimize blinded independent centralized review and investigator concordance using early, specialized, ovarian-cancer-specific radiology training to maximize validity of outcome data.

Concordance of Clinician-Documented and Imaging Response in Patients With Stage IV Non-Small Cell Lung Cancer Treated With First-Line Therapy

IMPORTANCE

In observational oncology studies of solid tumors, response to treatment can be evaluated based on electronic health record (EHR) documentation (clinician-assessed response [CAR]), an approach different from standardized radiologist-measured response (Response Evaluation Criteria in Solid Tumours [RECIST] 1.1).

OBJECTIVE

To evaluate the feasibility of an imaging response based on RECIST (IRb-RECIST) and the concordance between CAR and imaging response based on RECIST assessments, and investigate discordance causes.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study used an EHR-derived, deidentified database that included patients with stage IV non-small cell lung cancer (NSCLC) diagnosed between January 1, 2011, to June 30, 2019, selected from 3 study sites. Data analysis was conducted in August, 2020.

EXPOSURES

Undergoing first-line therapy and imaging assessments of response to treatment.

MAIN OUTCOMES AND MEASURES

In this study, CAR assessments (referred to in prior publications as "real-world response" [rwR]) were defined as clinician-documented changes in disease burden at radiologic evaluation time points; they were abstracted manually and assigned to response categories. The RECIST-based assessments accommodated routine practice patterns by using a modified version of RECIST 1.1 (IRb-RECIST), with independent radiology reads. Concordance was calculated as the percent agreement across all response categories and across a dichotomous stratification (response [complete or partial] vs no response), unconfirmed or confirmed.

RESULTS

This study found that, in 100 patients evaluated for concordance, agreement between CAR and IRb-RECIST was 71% (95% CI, 61%-80%), and 74% (95% CI, 64%-82%) for confirmed and unconfirmed response, respectively. There were more responders using CAR than IRb-RECIST (40 vs 29 with confirmation; 64 vs 43 without confirmation). The main sources of discordance were the different use of thresholds for tumor size changes by RECIST vs routine care, and unavailable baseline or follow-up scans resulting in inconsistent anatomic coverage over time.

CONCLUSIONS AND RELEVANCE

In this cohort study of patients with stage IV NSCLC, we collected routine-care imaging, showing the feasibility of response evaluation using IRb-RECIST criteria with independent centralized review. Concordance between CAR and centralized IRb-RECIST was moderate. Future work is needed to evaluate the generalizability of these results to broader populations, and investigate concordance in other clinical settings.

Estimands in hematologic oncology trials

The estimand framework included in the addendum to the ICH E9 guideline facilitates discussions to ensure alignment between the key question of interest, the analysis, and interpretation. Therapeutic knowledge and drug mechanism play a crucial role in determining the strategy and defining the estimand for clinical trial designs. Clinical trials in patients with hematological malignancies often present unique challenges for trial design due to complexity of treatment options and existence of potential curative but highly risky procedures, for example, stem cell transplant or treatment sequence across different phases (induction, consolidation, maintenance). Here, we illustrate how to apply the estimand framework in hematological clinical trials and how the estimand framework can address potential difficulties in trial result interpretation. This paper is a result of a cross-industry collaboration to connect the International Conference on Harmonisation (ICH) E9 addendum concepts to applications. Three randomized phase 3 trials will be used to consider common challenges including intercurrent events in hematologic oncology trials to illustrate different scientific questions and the consequences of the estimand choice for trial design, data collection, analysis, and interpretation. Template language for describing estimand in both study protocols and statistical analysis plans is suggested for statisticians' reference.

Radiologists and Clinical Trials: Part 1 The Truth About Reader Disagreements

The debate over human visual perception and how medical images should be interpreted have persisted since X-rays were the only imaging technique available. Concerns over rates of disagreement between expert image readers are associated with much of the clinical research and at times driven by the belief that any image endpoint variability is problematic. The deeper understanding of the reasons, value, and risk of disagreement are somewhat siloed, leading, at times, to costly and risky approaches, especially in clinical trials. Although artificial intelligence promises some relief from mistakes, its routine application for assessing tumors within cancer trials is still an aspiration. Our consortium of international experts in medical imaging for drug development research, the Pharma Imaging Network for Therapeutics and Diagnostics (PINTAD), tapped the collective knowledge of its members to ground expectations, summarize common reasons for reader discordance, identify what factors can be controlled and which actions are likely to be effective in reducing discordance. Reinforced by an exhaustive literature review, our work defines the forces that shape reader variability. This review article aims to produce a singular authoritative resource outlining reader performance's practical realities within cancer trials, whether they occur within a clinical or an independent central review.

Exaggeration of PFS by blinded, independent, central review (BICR)

BACKGROUND

Recent published studies have shown meaningful discrepancies between local investigator and blinded, independent, central review (BICR) assessed median progression-free survival (PFS). When the local review but not BICR shows progression, generally, no further assessments are carried out and patients are censored in the BICR analysis, leading to violation of the statistical assumptions of independence between censoring and outcome used in survival analysis methods.

METHODS

We carried out a simulation study to assess methodological reasons behind these discrepancies and corroborated our findings in a case study of three BRCA-mutated ovarian cancer trials. We briefly outline possible methodological solutions that may lead to improved estimation of the BICR medians.

RESULTS

The Kaplan-Meier (KM) curve for the BICR PFS can often be exaggerated. The degree of bias is largest when there is reasonably strong correlation between BICR and local PFS, especially when PFS is long compared with assessment frequency. This can result in an exaggeration of the medians and their difference; however, the hazard ratio (HR) is much less susceptible to bias. Our simulation shows that when the true BICR median PFS was 19 months, and patients assessed every 12 weeks, the estimated KM curves were materially biased whenever the correlation between BICR and local PFS was 0.4 or greater. This was corroborated by case studies where, in the active arm, the BICR median PFS was between 6 and 11 months greater than the local median PFS. Further research is required to find improved methods for estimating BICR survival curves.

CONCLUSIONS

In general, when there is a difference between local and BICR medians, the true BICR KM curve is likely to be exaggerated and its true median will probably lie somewhere between the observed local and BICR medians. Presentation of data should always include both BICR and local results whenever a BICR is carried out.

Systematic bias between blinded independent central review and local assessment: literature review and analyses of 76 phase III randomised controlled trials in 45 688 patients with advanced solid tumour

OBJECTIVE

Unbiased assessment of tumour response is crucial in randomised controlled trials (RCTs). Blinded independent central review is usually used as a supplemental or monitor to local assessment but is costly. The aim of this study is to investigate whether systematic bias existed in RCTs by comparing the treatment effects of efficacy endpoints between central and local assessments.

DESIGN

Literature review, pooling analysis and correlation analysis.

DATA SOURCES

PubMed, from 1 January 2010 to 30 June 2017.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Eligible articles are phase III RCTs comparing anticancer agents for advanced solid tumours. Additionally, the articles should report objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS) or time to progression (TTP); the treatment effect of these endpoints, OR or HR, should be based on central and local assessments.

RESULTS

Of 76 included trials involving 45 688 patients, 17 (22%) trials reported their endpoints with statistically inconsistent inferences (p value lower/higher than the probability of type I error) between central and local assessments; among them, 9 (53%) trials had statistically significant inference based on central assessment. Pooling analysis presented no systematic bias when comparing treatment effects of both assessments (ORR: OR=1.02 (95% CI 0.97 to 1.07), p=0.42, I2=0%; DCR: OR=0.97 (95% CI 0.92 to 1.03), p=0.32, I2=0%); PFS: HR=1.01 (95% CI 0.99 to 1.02), p=0.32, I2=0%; TTP: HR=1.04 (95% CI 0.95 to 1.14), p=0.37, I2=0%), regardless of funding source, mask, region, tumour type, study design, number of enrolled patients, response assessment criteria, primary endpoint and trials with statistically consistent/inconsistent inferences. Correlation analysis also presented no sign of systematic bias between central and local assessments (ORR, DCR, PFS: r>0.90, p<0.01; TTP: r=0.90, p=0.29).

CONCLUSIONS

No systematic bias could be found between local and central assessments in phase III RCTs on solid tumours. However, statistically inconsistent inferences could be made in many trials between both assessments.

Evaluation bias in objective response rate and disease control rate between blinded independent central review and local assessment: a study-level pooled analysis of phase III randomized control trials in the past seven years

Background

In previous studies, complete-case implementation of blind independent central review has been considered unnecessary based on no sign of systematic bias between central and local assessments. In order to further evaluate its value, this study investigated evaluation status between both assessments in phase III trials of anti-cancer drugs for non-hematologic solid tumors.

Methods

Eligible trials were searched in PubMed with the date of Jan 1, 2010 to Jun 30, 2017. We compared objective response rate (ORR) and disease control rate (DCR) between central and local assessments by study-level pooled analysis and correlation analysis. In pooled analysis, direct comparison was measured by the odds ratio (OR) of central-assessed response status to local-assessed response status; to investigate evaluation bias between central and local assessments, the above calculated OR between experimental (exp-) and control (con-) arms were compared, measured by the ratio of OR.

Results

A total of 28 included trials involving 17,466 patients were included (28 with ORR, 16 with DCR). Pooled analysis showed central assessment reported lower ORR and DCR than local assessment, especially in trials with open-label design, central-assessed primary endpoint, and positive primary endpoint outcome, respectively. However, this finding could be found in both experimental [exp-ORR: OR=0.81 (95% CI: 0.76-0.87), P<0.01, I²=11%; exp-DCR: OR=0.90 (0.81-1.01), P=0.07, I²=42%] and control arms [con-ORR: OR=0.79 (0.72-0.85), P<0.01, I²=17%; con-DCR: OR=0.94 (0.86-1.02), P=0.14, I²=12%]. No sign of evaluation bias between two assessments was indicated through further analysis [ORR: ratio of OR=1.02 (0.97-1.07), P=0.42, I²=0%; DCR: ratio of OR=0.98 (0.93-1.03), P=0.37, I²=0%], regardless of mask (open/blind), sample size, tumor type, primary endpoint (central-assessed/local-assessed), and primary endpoint outcome (positive/negative). Correlation analysis demonstrated a high-degree concordance between central and local assessments (exp-ORR, con-ORR, exp-DCR, con-DCR: r>0.90, P<0.01).

Conclusions

Blind independent central review remained irreplaceable to monitor local assessment, but its complete-case implementation may be unnecessary.

Comparison between site and central radiological assessments for patients with recurrent glioblastoma on a clinical trial

AIM

Assessment of magnetic resonance imaging (MRI) in glioblastoma can be challenging. For patients with recurrent glioblastoma managed on the CABARET trial, we compared disease status assessed at hospitals and subsequent blinded central expert radiological review.

METHODS

MRI results and clinical status at specified time points were used for site and central assessment of disease status. Clinical status was determined by the site. Response Assessment in Neuro-Oncology (RANO) criteria were used for both assessments. Site and central assessments of progression-free survival (PFS) and response rates were compared. Inter-rater variability for central review progression dates was assessed.

RESULTS

Central review resulted in shorter PFS in 45% of 89 evaluable patients (n = 40). Median PFS was 3.6 (central) versus 3.9 months (site) (hazard ratio 1.5, 95% confidence interval 1.3-1.8, P < 0.001). Responses were documented more frequently by sites (n = 16, 18%) than centrally (n = 11, 12%). Seven of 120 patients continued on trial without site-determined progression for more than 6 months beyond the central review determination of progression. Of scans reviewed by all three central reviewers, 33% were fully concordant for progression date.

CONCLUSION

While the difference between site and central PFS dates was statistically significant, the 0.3-month median difference is small. The variability within central review is consistent with previous studies, highlighting the challenges in MRI interpretation in this context. A small proportion of patients benefited from treatment well beyond the centrally determined progression date, reinforcing that clinical status together with radiology results are important determinants of whether a therapy is effective for an individual.

Investigator and independent review committee exploratory assessment and verification of tumor response in a non-Hodgkin lymphoma study

Interpretation of endpoints (e.g. overall response rate) in clinical trials depends on the accurate and reliable measurement and identification of tumors. Regulatory agencies recommend blinded reviews of imaging data by independent review committees (IRCs). Differences in response outcomes that arise between IRCs and site investigators raise regulatory/sponsor concerns. Here, we evaluate discrepant tumor response assessments by the IRC and unblinded investigators (complete versus partial response, respectively) occurring in 52 (13% of 393 IRC-assessed responders) of 447 enrolled patients with treatment-naïve non-Hodgkin lymphoma from a randomized study. The IRC and investigators were 'likely correct' in 73% and 25% of cases, respectively (p < .001). Investigators were more likely to make errors by misinterpreting lymph node data and not utilizing PET results. This post hoc finding suggests a possible role for post-training site evaluation/audit, with retraining as needed, and a specialized consensus committee for concurrent blinded review of site/central data.

Response assessment in lymphoma: Concordance between independent central review and local evaluation in a clinical trial setting

BACKGROUND

Independent central review of clinical imaging remains the standard for oncology clinical trials with registration potential. A limited independent central review strategy has been proposed for solid tumor trials based on concordance between central and local evaluation of response. Concordance between independent central review and local evaluation of response in hematological malignancies is not known.

METHODS

We retrospectively evaluated concordance between prospectively performed central and local assessments of response using the Revised Response Criteria for Malignant Lymphoma across two international, open-label, single-arm, registration studies of brentuximab vedotin in patients with relapsed or refractory Hodgkin lymphoma (N = 102) or systemic anaplastic large-cell lymphoma (N = 58).

RESULTS

Overall objective response rates were similar between assessors for both the trial in Hodgkin lymphoma (75% independent central review, 72% local evaluation) and the trial in anaplastic large-cell lymphoma (86% independent central review, 83% local evaluation). Patient-specific objective response concordance was also substantial (Hodgkin lymphoma: kappa = 0.68; anaplastic large-cell lymphoma: kappa = 0.74). Median progression-free survival was similar between assessors for patients with anaplastic large-cell lymphoma (14.3 months by independent central review (95% confidence interval: 6.9, -); 14.5 months by local evaluation (95% confidence interval: 9.4, -)), but longer by local evaluation in patients with Hodgkin lymphoma (5.8 months by independent central review (95% confidence interval: 5.0, 9.0); 9.0 months by local evaluation (95% confidence interval: 7.1, 12.0)). Median duration of response was longer by local evaluation in both malignancies, which was primarily attributable to earlier computed tomography and positron emission tomography-based scoring of progression by independent central review.

CONCLUSION

A limited independent review audit strategy for clinical trials of some lymphomas appears feasible and practical based on substantial concordance in assessments of overall objective response by central and local evaluation in two international, prospective, registration trials in lymphoma. Some variability between assessors in the time-to-event endpoints was observed, which appeared attributable to earlier assignments of progression by independent central review compared with local evaluation.

Afatinib beyond progression in patients with non-small-cell lung cancer following chemotherapy, erlotinib/gefitinib and afatinib: phase III randomized LUX-Lung 5 trial

BACKGROUND

Afatinib has demonstrated clinical benefit in patients with non-small-cell lung cancer progressing after treatment with erlotinib/gefitinib. This phase III trial prospectively assessed whether continued irreversible ErbB-family blockade with afatinib plus paclitaxel has superior outcomes versus switching to chemotherapy alone in patients acquiring resistance to erlotinib/gefitinib and afatinib monotherapy.

PATIENTS AND METHODS

Patients with relapsed/refractory disease following ≥1 line of chemotherapy, and whose tumors had progressed following initial disease control (≥12 weeks) with erlotinib/gefitinib and thereafter afatinib (50 mg/day), were randomized 2:1 to receive afatinib plus paclitaxel (40 mg/day; 80 mg/m(2)/week) or investigator's choice of single-agent chemotherapy. The primary end point was progression-free survival (PFS). Other end points included objective response rate (ORR), overall survival (OS), safety and patient-reported outcomes.

RESULTS

Two hundred and two patients with progressive disease following clinical benefit from afatinib were randomized to afatinib plus paclitaxel (n = 134) or single-agent chemotherapy (n = 68). PFS (median 5.6 versus 2.8 months, hazard ratio 0.60, P = 0.003) and ORR (32.1% versus 13.2%, P = 0.005) significantly improved with afatinib plus paclitaxel. There was no difference in OS. Global health status/quality of life was maintained with afatinib plus paclitaxel over the entire treatment period. The median treatment duration was 133 and 51 days with afatinib plus paclitaxel and single-agent chemotherapy, respectively; 48.5% of patients receiving afatinib plus paclitaxel and 30.0% of patients receiving single-agent chemotherapy experienced drug-related grade 3/4 adverse events. Treatment-related adverse events were consistent with those previously reported with each agent.

CONCLUSION

Afatinib plus paclitaxel improved PFS and ORR compared with single-agent chemotherapy in patients who acquired resistance to erlotinib/gefitinib and progressed on afatinib after initial benefit. LUX-Lung 5 is the first prospective trial to demonstrate the benefit of continued ErbB targeting post-progression, versus switching to single-agent chemotherapy.

TRIAL REGISTRATION NUMBER

NCT01085136 (clinicaltrials.gov).

Observer variability in RECIST-based tumour burden measurements: a meta-analysis

BACKGROUND

Response Evaluation Criteria in Solid Tumours (RECIST)-based tumour burden measurements involve observer variability, the extent of which ought to be determined.

METHODS

A literature search identified studies on observer variability during manual measurements of tumour burdens via computed tomography according to the RECIST guideline. The 95% limit of agreement (LOA) values of relative measurement difference (RMD) were pooled using a random-effects model.

RESULTS

Twelve studies were included. Pooled 95% LOAs of RMD in measuring unidimensional longest diameters of single lesions ranged from -22.1% (95% confidence interval [CI], -30.3% to -14.0%) to 25.4% (95% CI, 17.2% to 33.5%) between observers and -17.8% (95% CI, -23.6% to -11.9%) to 16.1% (95% CI, 10.1% to 21.8%) for a single observer. Pooled 95% LOAs of RMD in measuring the sum of multiple lesions ranged from -19.2% (95% CI, -23.7% to -14.9%) to 19.5% (95% CI, 15.2% to 23.9%) between observers, and -9.8% (95% CI, -19.0% to -0.3%) to 13.1% (95% CI, 3.6% to 22.6%) for a single observer. Pooled 95% LOA of RMD in calculating the interval change of tumour burden with a single lesion ranged from -31.3% (95% CI, -46.0% to -16.5%) to 30.3% (95% CI, 15.3% to 44.8%) between observers. Studies on calculating the interval change of tumour burden for a single observer or with multiple lesions were lacking.

CONCLUSION

Interobserver RMD in measuring single tumour burden and calculating its interval change may exceed the 20% cut-off for progression. Variability decreased when tumour burden was measured by a single observer or assessed by the sum of multiple lesions.

A risk management approach for imaging biomarker-driven clinical trials in oncology

Imaging has steadily evolved in clinical cancer research as a result of improved conventional imaging methods and the innovation of new functional and molecular imaging techniques. Despite this evolution, the design and data quality derived from imaging within clinical trials are not ideal and gaps exist with paucity of optimised methods, constraints of trial operational support, and scarce resources. Difficulties associated with integrating imaging biomarkers into trials have been neglected compared with inclusion of tissue and blood biomarkers, largely because of inherent challenges in the complexity of imaging technologies, safety issues related to new imaging contrast media, standardisation of image acquisition across multivendor platforms, and various postprocessing options available with advanced software. Ignorance of these pitfalls directly affects the quality of the imaging read-out, leading to trial failure, particularly when imaging is a primary endpoint. Therefore, we propose a practical risk-based framework and recommendations for trials driven by imaging biomarkers, which allow identification of risks at trial initiation to better allocate resources and prioritise key tasks.

Model free audit methodology for bias evaluation of tumour progression in oncology

Many oncology studies incorporate a blinded independent central review (BICR) to make an assessment of the integrity of the primary endpoint, progression free survival. Recently, it has been suggested that, in order to assess the potential for bias amongst investigators, a BICR amongst only a sample of patients could be performed; if evidence of bias is detected, according to a predefined threshold, the BICR is then assessed in all patients, otherwise, it is concluded that the sample was sufficient to rule out meaningful levels of bias. In this paper, we present an approach that adapts a method originally created for defining futility bounds in group sequential designs. The hazard ratio ratio, the ratio of the hazard ratio (HR) for the treatment effect estimated from the BICR to the corresponding HR for the investigator assessments, is used as the metric to define bias. The approach is simple to implement and ensures a high probability that a substantial true bias will be detected. In the absence of bias, there is a high probability of accepting the accuracy of local evaluations based on the sample, in which case an expensive BICR of all patients is avoided. The properties of the approach are demonstrated by retrospective application to a completed Phase III trial in colorectal cancer. The same approach could easily be adapted for other disease settings, and for test statistics other than the hazard ratio.

Volume-based response evaluation with consensual lesion selection: a pilot study by using cloud solutions and comparison to RECIST 1.1

RATIONALE AND OBJECTIVES

Lesion volume is considered as a promising alternative to Response Evaluation Criteria in Solid Tumors (RECIST) to make tumor measurements more accurate and consistent, which would enable an earlier detection of temporal changes. In this article, we report the results of a pilot study aiming at evaluating the effects of a consensual lesion selection on volume-based response (VBR) assessments.

MATERIALS AND METHODS

Eleven patients with lung computed tomography scans acquired at three time points were selected from Reference Image Database to Evaluate Response to therapy in lung cancer (RIDER) and proprietary databases. Images were analyzed according to RECIST 1.1 and VBR criteria by three readers working in different geographic locations. Cloud solutions were used to connect readers and carry out a consensus process on the selection of lesions used for computing response. Because there are not currently accepted thresholds for computing VBR, we have applied a set of thresholds based on measurement variability (-35% and +55%). The benefit of this consensus was measured in terms of multiobserver agreement by using Fleiss kappa (κfleiss) and corresponding standard errors (SE).

RESULTS

VBR after consensual selection of target lesions allowed to obtain κfleiss = 0.85 (SE = 0.091), which increases up to 0.95 (SE = 0.092), if an extra consensus on new lesions is added. As a reference, the agreement when applying RECIST without consensus was κfleiss = 0.72 (SE = 0.088). These differences were found to be statistically significant according to a z-test.

CONCLUSIONS

An agreement on the selection of lesions allows reducing the inter-reader variability when computing VBR. Cloud solutions showed to be an interesting and feasible strategy for standardizing response evaluations, reducing variability, and increasing consistency of results in multicenter clinical trials.

Trastuzumab emtansine versus treatment of physician's choice for pretreated HER2-positive advanced breast cancer (TH3RESA): a randomised, open-label, phase 3 trial

BACKGROUND

Patients with progressive disease after two or more HER2-directed regimens for recurrent or metastatic breast cancer have few effective therapeutic options. We aimed to compare trastuzumab emtansine, an antibody-drug conjugate comprising the cytotoxic agent DM1 linked to trastuzumab, with treatment of physician's choice in this population of patients.

METHODS

This randomised, open-label, phase 3 trial took place in medical centres in 22 countries across Europe, North America, South America, and Asia-Pacific. Eligible patients (≥18 years, left ventricular ejection fraction ≥50%, Eastern Cooperative Oncology Group performance status 0-2) with progressive HER2-positive advanced breast cancer who had received two or more HER2-directed regimens in the advanced setting, including trastuzumab and lapatinib, and previous taxane therapy in any setting, were randomly assigned (in a 2:1 ratio) to trastuzumab emtansine (3·6 mg/kg intravenously every 21 days) or physician's choice using a permuted block randomisation scheme by an interactive voice and web response system. Patients were stratified according to world region (USA vs western Europe vs other), number of previous regimens (excluding single-agent hormonal therapy) for the treatment of advanced disease (two to three vs more than three), and presence of visceral disease (any vs none). Coprimary endpoints were investigator-assessed progression-free survival (PFS) and overall survival in the intention-to-treat population. We report the final PFS analysis and the first interim overall survival analysis. This study is registered with ClinicalTrials.gov, number NCT01419197.

FINDINGS

From Sept 14, 2011, to Nov 19, 2012, 602 patients were randomly assigned (404 to trastuzumab emtansine and 198 to physician's choice). At data cutoff (Feb 11, 2013), 44 patients assigned to physician's choice had crossed over to trastuzumab emtansine. After a median follow-up of 7·2 months (IQR 5·0-10·1 months) in the trastuzumab emtansine group and 6·5 months (IQR 4·1-9·7) in the physician's choice group, 219 (54%) patients in the trastuzumab emtansine group and 129 (65%) of patients in the physician's choice group had PFS events. PFS was significantly improved with trastuzumab emtansine compared with physician's choice (median 6·2 months [95% CI 5·59-6·87] vs 3·3 months [2·89-4·14]; stratified hazard ratio [HR] 0·528 [0·422-0·661]; p<0·0001). Interim overall survival analysis showed a trend favouring trastuzumab emtansine (stratified HR 0·552 [95% CI 0·369-0·826]; p=0·0034), but the stopping boundary was not crossed. A lower incidence of grade 3 or worse adverse events was reported with trastuzumab emtansine than with physician's choice (130 events [32%] in 403 patients vs 80 events [43%] in 184 patients). Neutropenia (ten [2%] vs 29 [16%]), diarrhoea (three [<1%] vs eight [4%]), and febrile neutropenia (one [<1%] vs seven [4%]) were grade 3 or worse adverse events that were more common in the physician's choice group than in the trastuzumab emtansine group. Thrombocytopenia (19 [5%] vs three [2%]) was the grade 3 or worse adverse event that was more common in the trastuzumab emtansine group. 74 (18%) patients in the trastuzumab emtansine group and 38 (21%) in the physician's choice group reported a serious adverse event.

INTERPRETATION

Trastuzumab emtansine should be considered as a new standard for patients with HER2-positive advanced breast cancer who have previously received trastuzumab and lapatinib.

FUNDING

Genentech.

An audit strategy for time-to-event outcomes measured with error: application to five randomized controlled trials in oncology

BACKGROUND

Measurement error in time-to-event end points complicates interpretation of treatment effects in clinical trials. Non-differential measurement error is unlikely to produce large bias [1]. When error depends on treatment arm, bias is of greater concern. Blinded-independent central review (BICR) of all images from a trial is commonly undertaken to mitigate differential measurement-error bias that may be present in hazard ratios (HRs) based on local evaluations. Similar BICR and local evaluation HRs may provide reassurance about the treatment effect, but BICR adds considerable time and expense to trials.

METHODS

We describe a BICR audit strategy [2] and apply it to five randomized controlled trials to evaluate its use and to provide practical guidelines. The strategy requires BICR on a subset of study subjects, rather than a complete-case BICR, and makes use of an auxiliary-variable estimator.

RESULTS

When the effect size is relatively large, the method provides a substantial reduction in the size of the BICRs. In a trial with 722 participants and a HR of 0.48, an average audit of 28% of the data was needed and always confirmed the treatment effect as assessed by local evaluations. More moderate effect sizes and/or smaller trial sizes required larger proportions of audited images, ranging from 57% to 100% for HRs ranging from 0.55 to 0.77 and sample sizes between 209 and 737.

LIMITATIONS

The method is developed for a simple random sample of study subjects. In studies with low event rates, more efficient estimation may result from sampling individuals with events at a higher rate.

CONCLUSION

The proposed strategy can greatly decrease the costs and time associated with BICR, by reducing the number of images undergoing review. The savings will depend on the underlying treatment effect and trial size, with larger treatment effects and larger trials requiring smaller proportions of audited data.