Validation of surrogate endpoints in advanced solid tumors: systematic review of statistical methods, results, and implications for policy makers

Intermediate clinical endpoints in early-stage breast cancer: an analysis of individual patient data from the Gruppo Italiano Mammella and Mammella Intergruppo trials

Background

Intermediate clinical endpoints (ICEs) are frequently used as primary endpoint in randomised trials (RCTs). We aim to assess whether changes in different ICEs can be used to predict changes in overall survival (OS) in adjuvant breast cancer trials.

Methods

Individual patient level data from adjuvant phase III RCTs conducted by the Gruppo Italiano Mammella (GIM) and Mammella Intergruppo (MIG) study groups were used. ICEs were computed according to STEEP criteria. Using a two-stage meta-analytic model, we assessed the surrogacy of each ICE at both the outcome (i.e., OS and ICE are correlated irrespective of treatment) and trial (i.e., treatment effects on ICE and treatment effect on OS are correlated) levels. The following ICEs were considered as potential surrogate endpoints of OS: disease-free survival (DFS), distant disease-free survival (DDFS), distant relapse-free survival (DRFS), recurrence-free survival (RFS), recurrence-free interval (RFI), distant recurrence-free interval (DRFI), breast cancer-free interval (BCFI), and invasive breast cancer-free survival (IBCFS). The estimates of the degree of correlation were obtained by copula models and weighted linear regression. Kendall's τ and R2 ≥ 0.70 were considered as indicators of a clinically relevant surrogacy.

Findings

Among the 12,397 patients enrolled from November 1992 to July 2012 in six RCTs, median age at enrolment was 57 years (interquartile range (IQR) 49-65). After a median follow-up of 10.3 years (IQR 6.4-14.5), 2131 (17.2%) OS events were observed, with 1390 (65.2%) attributed to breast cancer. At the outcome-level, Kendall's τ ranged from 0.69 for BCFI to 0.84 for DRFS. For DFS, DDFS, DRFS, RFS, RFI, DRFI, BCFI, and IBCFS endpoints, over 95% of the 8-year OS variability was attributable to the variation of the 5-year ICE. At the trial-level, treatment effects for the different ICEs and OS were strongly correlated, with the highest correlation for RFS and DRFS and the lowest for BCFI.

Interpretation

Our results provide evidence supporting the use of DFS, DDFS, DRFS, RFS, RFI, DRFI, and IBCFS as primary endpoint in breast cancer adjuvant trials.

Funding

This analysis was supported by the Italian Association for Cancer Research ("Associazione Italiana per la Ricerca sul Cancro", AIRC; IG 2017/20760) and by Italian Ministry of Health-5 × 1000 funds (years 2021-2022).

Validation of metastasis-free survival as a surrogate endpoint for overall survival in localized prostate cancer in the era of docetaxel for castration-resistant prostate cancer

BACKGROUND

Prior work from the Intermediate Clinical Endpoints in Cancer of the Prostate (ICECaP) consortium (ICECaP-1) demonstrated that metastasis-free survival (MFS) is a valid surrogate for overall survival (OS) in localized prostate cancer (PCa). This was based on data from patients treated predominantly before 2004, prior to docetaxel being available for the treatment of metastatic castrate-resistant prostate cancer (mCRPC). We sought to validate surrogacy in a more contemporary era (ICECaP-2) with greater availability of docetaxel and other systemic therapies for mCRPC.

PATIENTS AND METHODS

Eligible trials for ICECaP-2 were those providing individual patient data (IPD) after publication of ICECaP-1 and evaluating adjuvant/salvage therapy for localized PCa, and which collected MFS and OS data. MFS was defined as distant metastases or death from any cause, and OS was defined as death from any cause. Surrogacy was evaluated using a meta-analytic two-stage validation model, with an R2 ≥ 0.7 defined a priori as clinically relevant.

RESULTS

A total of 15 164 IPD from 14 trials were included in ICECaP-2, with 70% of patients treated after 2004. The median follow-up was 8.3 years and the median postmetastasis survival was 3.1 years in ICECaP-2, compared with 1.9 years in ICECaP-1. For surrogacy condition 1, Kendall's tau was 0.92 for MFS with OS at the patient level, and R2 from weighted linear regression (WLR) of 8-year OS on 5-year MFS was 0.73 (95% confidence interval 0.53-0.82) at the trial level. For condition 2, R2 was 0.83 (95% confidence interval 0.64-0.89) from WLR of log[hazard ratio (HR)]-OS on log(HR)-MFS. The surrogate threshold effect on OS was an HR(MFS) of 0.81.

CONCLUSIONS

MFS remained a valid surrogate for OS in a more contemporary era, where patients had greater access to docetaxel and other systemic therapies for mCRPC. This supports the use of MFS as the primary outcome measure for ongoing adjuvant trials in localized PCa.

Adapting Health Technology Assessment agency standards for surrogate outcomes in early stage cancer trials: what needs to happen?

INTRODUCTION

An avalanche of early stage cancer clinical trials is coming. The majority of these solely use surrogate outcomes that have not been validated against a target outcome of interest (e.g. overall survival). Current HTA guidance on surrogate outcome validation are not methodologically or practically conducive to this scenario.

AREAS COVERED

We provide a high-level overview of methods, approaches, and conceptual thinking for making better use of limited evidence within early stage cancer HTA submissions. We outline regulatory and HTA issues and emphasize how evidence transitions from one to another, what major gaps currently exist, and how these may be bridged. We summarize current methodologies and practices, their pros and cons. We outline how complementary measurements strengthen evaluations and address fallacies and biases of conventional statistical methods for surrogate outcomes validation. The value of real-world data to support some of the necessary validity components is discussed. Lastly, we address the importance of the patient voice for better understanding which surrogate outcomes may appropriately inform HTA.

EXPERT OPINION

Conventional surrogate outcome validation represents a fraught and sub-optimal framework for HTA purposes, particularly for early stage cancer. Tools for optimizing use of limited evidence exist. Education of stakeholders is highly needed.

A Surrogate Endpoint for Overall Survival in Locally Advanced and Resectable Esophageal Squamous Cell Carcinoma: A Reanalysis of Data From the NEOCRTEC5010 Trial

PURPOSE

This study aimed to investigate disease-free survival (DFS) as a surrogate endpoint for overall survival (OS) in patients with locally advanced and resectable esophageal squamous cell carcinoma.

METHODS AND MATERIALS

We re-analyzed patient data from the NEOCRTEC5010 randomized controlled trial (N = 451 patients) to compare their OS with that of an age- and sex-matched cohort from the general population of China. We used expected survival and the standardized mortality ratio, respectively, in our analysis of data collected from a neoadjuvant chemoradiation therapy (NCRT) plus surgery group and a surgery-only group. Published data from 6 randomized controlled trials and 20 retrospective studies were used to examine the correlation between DFS and OS at the trial level.

RESULTS

The annual hazard rate of disease progression decreased to 4.9% and 8.1% within 3 years in the NCRT and surgery groups, respectively. Patients who were disease-free at 36 months had a 5-year OS of 93.9% (95% CI, 89.7%-98.4%) in the NCRT group with a standardized mortality ratio of 1.1 (95% CI, 0.7-1.8; P = .5639). In contrast, the 5-year OS was only 12.9% (95% CI, 7.3%-22.6%) for patients in the NCRT group who exhibited disease progression within 36 months. At the trial level, DFS and OS were correlated with treatment effect (R2 = 0.605).

CONCLUSIONS

Disease-free status at 36 months is a valid surrogate endpoint for 5-year OS in patients with locally advanced and resectable esophageal squamous cell carcinoma. Patients who were disease-free at 36 months showed a favorable OS, which was indistinguishable from that of the age- and sex-matched comparison group from the general population; otherwise, their 5-year OS was extremely poor.

Biochemical Recurrence Surrogacy for Clinical Outcomes After Radiotherapy for Adenocarcinoma of the Prostate

PURPOSE

The surrogacy of biochemical recurrence (BCR) for overall survival (OS) in localized prostate cancer remains controversial. Herein, we evaluate the surrogacy of BCR using different surrogacy analytic methods.

MATERIALS AND METHODS

Individual patient data from 11 trials evaluating radiotherapy dose escalation, androgen deprivation therapy (ADT) use, and ADT prolongation were obtained. Surrogate candidacy was assessed using the Prentice criteria (including landmark analyses) and the two-stage meta-analytic approach (estimating Kendall's tau and the R2). Biochemical recurrence-free survival (BCRFS, time from random assignment to BCR or any death) and time to BCR (TTBCR, time from random assignment to BCR or cancer-specific deaths censoring for noncancer-related deaths) were assessed.

RESULTS

Overall, 10,741 patients were included. Dose escalation, addition of short-term ADT, and prolongation of ADT duration significantly improved BCR (hazard ratio [HR], 0.71 [95% CI, 0.63 to 0.79]; HR, 0.53 [95% CI, 0.48 to 0.59]; and HR, 0.54 [95% CI, 0.48 to 0.61], respectively). Adding short-term ADT (HR, 0.91 [95% CI, 0.84 to 0.99]) and prolonging ADT (HR, 0.86 [95% CI, 0.78 to 0.94]) significantly improved OS, whereas dose escalation did not (HR, 0.98 [95% CI, 0.87 to 1.11]). BCR at 48 months was associated with inferior OS in all three groups (HR, 2.46 [95% CI, 2.08 to 2.92]; HR, 1.51 [95% CI, 1.35 to 1.70]; and HR, 2.31 [95% CI, 2.04 to 2.61], respectively). However, after adjusting for BCR at 48 months, there was no significant treatment effect on OS (HR, 1.10 [95% CI, 0.96 to 1.27]; HR, 0.96 [95% CI, 0.87 to 1.06] and 1.00 [95% CI, 0.90 to 1.12], respectively). The patient-level correlation (Kendall's tau) for BCRFS and OS ranged between 0.59 and 0.69, and that for TTBCR and OS ranged between 0.23 and 0.41. The R2 values for trial-level correlation of the treatment effect on BCRFS and TTBCR with that on OS were 0.563 and 0.160, respectively.

CONCLUSION

BCRFS and TTBCR are prognostic but failed to satisfy all surrogacy criteria. Strength of correlation was greater when noncancer-related deaths were considered events.

Regulatory benefit-risk assessment of oncology drugs: A systematic review of FDA and EMA approvals

The European Medicines Agency (EMA) and FDA have policy goals of strengthening benefit-risk (B-R) capabilities; but how this has been translating into regulatory practice is unclear. A systematic review of oncology drug approvals between 2015 and 2020 was conducted with approvals identified through review of FDA and EMA annual reports, with extraction of information on submission, clinical program and B-R assessment from publicly available review documents. Data were extracted from 236 reviews (EMA: 66 new submissions, 100 label extensions; FDA: 70 new submissions). The standard of evidence for B-R assessments seems to have diversified over time; yet, despite policy targets to extend their use, these assessments rarely include patient experience or real-world data.

Association Between Intermediate End Points, Progression-free Survival, and Overall Survival in First-line Advanced or Recurrent Endometrial Cancer

PURPOSE

Advanced/recurrent endometrial cancer is associated with poor long-term outcomes. Clinical studies of novel regimens are ongoing, but given that data on overall survival (OS) take a long time to mature, surrogate end points are often used to support clinical-research interpretation. The aim of this study was to explore the correlation between progression-free survival (PFS)/time to progression (TTP) and OS across multiple time points in the first-line treatment of advanced/recurrent endometrial cancer.

METHODS

This study comprised meta-analyses of Phase 2/3 randomized, controlled trials of first-line treatments in patients with advanced primary or first-recurrent endometrial cancer identified via systematic literature review. The strength of the surrogacy relationship was assessed by correlation analyses (estimated with Spearman and Pearson correlation coefficients) and weighted linear regression.

FINDINGS

Data from 15 studies were included. PFS and TTP (TTP was reported in one study only) were highly correlated with future OS at multiple time points (Spearman values, 0.83-0.90; Pearson values, 0.86-0.93), suggesting that a change in PFS/TTP would likely be correlated with a change in OS in the same direction. On weighted linear regression, a 10% increase in PFS/TTP probability was significantly associated with a 9.3% to 13.3% increase in the probability of future OS. The strong positive association between PFS/TTP and OS was supported by findings from sensitivity analyses based on identified sources of interstudy heterogeneity.

IMPLICATIONS

PFS/TTP is a good potential candidate for predicting long-term OS outcomes in trials of first-line treatment in patients with advanced/recurrent endometrial cancer. The findings from this report may help to inform health-authority and clinical decision makers that PFS/TTP improvements are likely to translate into subsequent OS improvements once data mature.

Intermediate endpoints as surrogates for outcomes in cancer immunotherapy: a systematic review and meta-analysis of phase 3 trials

Background

Cancer immunotherapy shows unique efficacy kinetics that differs from conventional treatment. These characteristics may lead to the prolongation of trial duration, hence reliable surrogate endpoints are urgently needed. We aimed to systematically evaluate the study-level performance of commonly reported intermediate clinical endpoints for surrogacy in cancer immunotherapy.

Methods

We searched the Embase, PubMed, and Cochrane databases, between database inception and October 18, 2022, for phase 3 randomised trials investigating the efficacy of immunotherapy in patients with advanced solid tumours. An updated search was done on July, 15, 2023. No language restrictions were used. Eligible trials had to set overall survival (OS) as the primary or co-primary endpoint and report at least one intermediate clinical endpoint including objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), and 1-year overall survival. Other key inclusion and exclusion criteria included: (1) adult patients (>18 years old) with advanced solid tumour; (2) no immunotherapy conducted in the control arms; (3) follow-up is long enough to achieve OS; (4) data should be public available. A two-stage meta-analytic approach was conducted to evaluate the magnitude of the association between these intermediate endpoints and OS. A surrogate was identified if the coefficient of determination (R2) was 0.7 or greater. Leave-one-out cross-validation and pre-defined subgroup analysis were conducted to examine the heterogeneity. Potential publication bias was evaluated using the Egger's and Begg's tests. This trial was registered with PROSPERO, number CRD42022381648.

Findings

52,342 patients with 15 types of tumours from 77 phase 3 studies were included. ORR (R2 = 0.11; 95% CI, 0.00-0.24), DCR (R2 = 0.01; 95% CI, 0.00-0.01), and PFS (R2 = 0.40; 95% CI, 0.23-0.56) showed weak associations with OS. However, a strong correlation was observed between 1-year survival and clinical outcome (R2 = 0.74; 95% CI, 0.64-0.83). These associations remained relatively consistent across pre-defined subgroups stratified based on tumour types, masking methods, line of treatments, drug targets, treatment strategies, and follow-up durations. No significant heterogeneities or publication bias were identified.

Interpretation

1-year milestone survival was the only identified surrogacy endpoint for outcomes in cancer immunotherapy. Ongoing investigations and development of new endpoints and incorporation of biomarkers are needed to identify potential surrogate markers that can be more robust than 1-year survival. This work may provide important references in assisting the design and interpretation of future clinical trials, and constitute complementary information in drafting clinical practice guidelines.

Funding

None.

The Evaluation of Drug Innovativeness in Italy: Key Determinants and Internal Consistency

BACKGROUND

Innovative medicines are provided with dedicated funds and immediate market access in Italy. Innovativeness evaluation considers unmet need, added therapeutic value, and quality of the evidence.

OBJECTIVE

We aimed to evaluate the internal consistency and drivers of the innovativeness appraisal process.

METHODS

Appraisal reports on innovativeness refer to 1997-2021. We used both a descriptive approach and probabilistic multivariate analysis, using logistic regression models to compute odds ratios and 95% confidence intervals. The dependent variable is innovativeness status (innovative vs. non-innovative; full innovativeness vs. conditional innovativeness). Explanatory variables, besides the three above-mentioned domains, are the year of evaluation, drug type, target disease and population, and the number and type of available studies.

RESULTS

Among the 141 medicines scrutinized, 31.9%, 29.8%, and 38.3% were evaluated as fully innovative, conditionally innovative, and non-innovative, respectively. Added therapeutic value and the quality of the evidence were associated with the odds of receiving innovative status, and full compared with conditional innovativeness; unmet need was not a predictive variable. Other factors played a minor role: medicines for both solid tumours and rare diseases are more likely to be judged innovative; conditional innovativeness is more probable for medicines for rare diseases.

CONCLUSIONS

Innovativeness status is driven by the added therapeutic value and quality of evidence. The appraisal process is internally consistent and predictable. This provides industry with a clear indication of what is needed to ensure that access to their medicines is prioritized.

Belgian observational survival data (incidence years 2004-2017) and expenditure for innovative oncology drugs in twelve cancer indications

BACKGROUND

The Food and Drug Administration and European Medicines Agency typically approve market access for cancer drugs based on surrogate end-points, which do not always translate into substantiated improvements in outcomes that matter the most to patients, i.e. survival and quality of life. These drugs often, also, have a high price tag. We assessed whether there was an increase in cancer drug expenditure for a broad selection of indications, and whether this correlates with increased overall survival.

METHODS

This cohort study used Belgian Cancer Registry data from 125,692 patients (12 cancer indications, incidence period 2004-2017), which was linked to reimbursement and survival data. This reliably represents the Belgian situation. One-to-five year observed survival probability, median survival time, oncology drug expenditure and mean oncology drug cost per patient were reviewed.

FINDINGS

In almost all indications, total expenditure and average treatment cost for oncology drugs increased over the years (2004-2017). In contrast, mixed findings are observed for the evolution in overall survival probability and median survival time. While an absolute improvement in the 3-year survival probability of about 10% is noticed in non-small-cell lung cancer and chronic myeloid leukaemia, improvements in about half of the other indications are limited or even absent.

INTERPRETATION

The Belgian observational data indicate that assuming 'innovative' oncology drugs always add value in terms of improved survival is often unjustified. The literature also highlights the problem of using surrogate end-points, and the lack of comparative evidence showing an added value of oncology drugs for both survival and quality of life at market approval or during the post-marketing phase. Comparative studies should be conducted in the pre-marketing phase that are suitable for registration purposes, aid reimbursement decisions and support physicians and patients when making treatment decisions.

Immune-related adverse events as potential surrogates of immune checkpoint inhibitors' efficacy: a systematic review and meta-analysis of randomized studies

BACKGROUND

Immune-related adverse events (irAEs) are frequently reported during immune checkpoint inhibitor (ICI) therapy and are associated with long-term outcomes. It is unknown if the irAE occurrence is a valid surrogate of ICIs' efficacy.

METHODS

We identified articles reporting the results of randomized trials of experimental ICI therapy in solid tumors with a systematic search. The control arms could be placebo, cytotoxic/targeted therapy, or ICI therapy. We extracted the hazard ratios for overall survival (OS) with the number of OS events per arm and the number and percentages of overall and specific irAEs of grade 1-2 and grade 3-4 per arm. We estimated the treatment effect on the potential surrogate outcome with the odds ratio of the irAE rate between the experimental and the control arm. The statistical analysis consisted of weighted linear regression on a logarithmic scale between treatment effects on irAE rate and treatment effects on OS.

RESULTS

Sixty-two randomized trials were included for a total of 79 contrasts and 42 247 patients. The analyses found no significant association between the treatment effects for overall grade 1-2 or grade 3-4 irAE rates or specific (skin, gastrointestinal, endocrine) irAE rates. In the non-small-cell lung cancer (NSCLC) trial subset, we observed a negative association between treatment effects on overall grade 1-2 irAEs and treatment effects on OS in studies with patients selected for programmed death-ligand 1 expression (R² = 0.55; 95% confidence interval 0.20-0.95; R = -0.69). In the melanoma trial subset, a negative association was shown between treatment effects on gastrointestinal grade 3-4 irAEs and treatment effects on OS in trials without an ICI-based control arm (R² = 0.77; 95% confidence interval 0.24-0.99; R = -0.89).

CONCLUSIONS

We found low-strength correlations between the ICI therapy effects on overall or specific irAE rates and the treatment effects on OS in several cancer types.

Development of a framework and decision tool for the evaluation of health technologies based on surrogate endpoint evidence

In the drive toward faster patient access to treatments, health technology assessment (HTA) agencies and payers are increasingly faced with reliance on evidence based on surrogate endpoints, increasing decision uncertainty. Despite the development of a small number of evaluation frameworks, there remains no consensus on the detailed methodology for handling surrogate endpoints in HTA practice. This research overviews the methods and findings of four empirical studies undertaken as part of COMED (Pushing the Boundaries of Cost and Outcome Analysis of Medical Technologies) program work package 2 with the aim of analyzing international HTA practice of the handling and considerations around the use of surrogate endpoint evidence. We have synthesized the findings of these empirical studies, in context of wider contemporary body of methodological and policy-related literature on surrogate endpoints, to develop a web-based decision tool to support HTA agencies and payers when faced with surrogate endpoint evidence. Our decision tool is intended for use by HTA agencies and their decision-making committees together with the wider community of HTA stakeholders (including clinicians, patient groups, and healthcare manufacturers). Having developed this tool, we will monitor its use and we welcome feedback on its utility.

An Analysis of 5-Level Version of EQ-5D Adjusting for Treatment Switching: The Case of Patients With Epidermal Growth Factor Receptor T790M-Positive Nonsmall Cell Lung Cancer Treated With Osimertinib

OBJECTIVES

Treatment switching from control to treatment after disease progression is common in oncology trials. Analyses of survival data typically adjust for this bias, but such adjustments are rarely performed in analyses of patient-reported outcomes. This analysis aimed to examine the impact of adjusting for treatment switching on estimated treatment effects on 5-level version of EQ-5D (EQ-5D-5L) utilities and quality-adjusted life-years (QALYs). The AURA3 trial (NCT02151981) was a randomized controlled trial comparing osimertinib with platinum-based doublet chemotherapy (standard care) in patients with locally advanced or metastatic epidermal growth factor receptor mutant- and T790M-positive nonsmall cell lung cancer whose disease has progressed with previous epidermal growth factor receptor tyrosine kinase inhibitor therapy.

METHODS

Descriptive analyses were used to compare treatment arms. The primary analysis used a 2-stage least squares instrumental variable regression to estimate treatment effect adjusting for treatment crossover. Time to deterioration, defined from baseline to minimally important deterioration in EQ-5D-5L utility, was assessed using a rank preserving structural failure time model.

RESULTS

Intention-to-treat analysis of imputed data showed incremental QALYs for osimertinib of 0.23 at 60 weeks. Accounting for treatment switching increased this to 0.52 in the primary analysis and to 0.63 QALYs in sensitivity analysis at 150 weeks. Time to deterioration analysis showed longer health-related quality of life maintenance with osimertinib, of 12.76 weeks, although this was at the borderline of statistical significance (acceleration factor, ψ = -0.275; 95% confidence interval -0.50 to 0.00).

CONCLUSIONS

This analysis demonstrates methods to adjust for treatment switching in the analysis of EQ-5D-5L from clinical trials. Failure to account for crossover substantially underestimated the QALY gain for osimertinib.

Oncology drugs and added benefit: insights from 3 European health technology assessment agencies on the role of efficacy endpoints

OBJECTIVE

This study aimed to understand the impact of different efficacy endpoints on reimbursement decisions made by health technology assessment (HTA) bodies.

MATERIALS AND METHODS

European Medicines Agency (EMA) oncology product marketing authorizations were screened to identify products that completed review by 3 HTA bodies during 2016-2019: United Kingdom's National Institute for Health and Care Excellence, Germany's Gemeinsamer Bundesausschuss, and France's Haute Autorité de Santé. Each decision's endpoint information, including overall survival (OS) and progression-free survival (PFS), was extracted. Each endpoint's influence on added benefits rating (the degree of added benefit as judged by the HTA agency) and full reimbursement (i.e. reimbursed population to label) decisions was tested using bivariate analyses.

RESULTS

An increasing trend was observed toward HTA submissions with immature OS data (36.8% and 71.4% in 2016 and 2019, respectively), which was a predictor of limited added benefit (p < .001). Regarding data availability, 63% of submissions provided OS, 2% provided PFS without OS; and 35% provided neither. OS availability significantly influenced added benefit (p < .001) but not full reimbursement (p > .05) decisions, whereas PFS without OS had no significant impact compared with either OS or PFS data for either outcome (p = .99).

CONCLUSIONS

The trend toward fewer products filing mature OS data over time suggests sponsors may be increasingly confident achieving reimbursement with surrogate endpoint data, although mature OS data provided the strongest correlation to positive reimbursement decisions. Notably, in some locally advanced settings, OS data maturity will take a long time to obtain. To expedite patient access to new medicines, payers should consider the acceptance of surrogate endpoints predictive of clinical benefit.

A meta-analysis on overall survival and safety outcomes in patients with nonmetastatic castration-resistant prostate cancer treated with novel hormonal agents

Several novel androgen receptor (AR)-inhibitors have been introduced for nonmetastatic castration-resistant prostate cancer (nmCRPC) treatment, with the improvement of survival outcomes which need to be balanced against the risk of adverse events. We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) investigating enzalutamide, apalutamide and darolutamide in nmCRPC patients, to assess overall survival (OS), incidence and risk of adverse drug events, adverse-events-related death and adverse-events-related treatment discontinuation. We selected three RCTs (SPARTAN, PROSPER and ARAMIS). New hormonal agents administration resulted in better OS, despite the increased risk of several any grade and grade 3-4 adverse events. In the decision-making process, careful evaluation of expected adverse events, patients' comorbidities and maintenance of quality of life are mandatory.

The Impasse on Overall Survival in Oncology Reimbursement Decision-Making: How Can We Resolve This?

Mature overall survival (OS) data are often unavailable at the time of regulatory and reimbursement decisions for a new cancer treatment. For patients with early-stage cancers treated with potentially curative treatments, demonstrating an OS benefit may take years and may be confounded by subsequent lines of therapy or crossover to the investigational treatment. For patients with advanced-stage cancers, mature OS data may be available but difficult to interpret for similar reasons. There are strong opinions about approval and reimbursement in the absence of mature OS data, with concerns over delay in patient access set against concerns about uncertainty in long-term benefit. This position paper reflects our individual views as patient advocate, clinician or health economist on one aspect of this debate. We look at payer decisions in the absence of mature OS data, considering when and how non-OS trial outcomes could inform decision-making and how uncertainty can be addressed beyond the trial, supporting these views with evidence from the literature. We consider when it is reasonable for payers to expect or not expect mature OS data at the initial reimbursement decision (based on criteria such as cancer stage and treatment efficacy) acknowledging that there are settings in which mature OS data are expected. We propose flexible strategies for generating and appraising patient-relevant evidence, including context-relevant endpoints and quality of life measures, when survival rates are good and mature OS data are not expected. We note that fair reimbursement is important; this means valuing patient benefit as shown through prespecified endpoints and reappraising if there is ongoing uncertainty or failure to show a sustained benefit. We suggest that reimbursement systems continue to evolve to align with scientific advances, because innovation is only meaningful if readily accessible to patients. The proposed strategies have the potential to promote thorough assessment of potential benefit to patients and lead to timely access to effective medicines.

Surrogate Endpoints in Oncology: Overview of Systematic Reviews and Their Use for Health Decision Making in Mexico

OBJECTIVES

The use of surrogate endpoints (SEs) for cancer drug approval in health systems is common. The objectives of this study were to identify systematic reviews (SRs) that evaluated the correlation of SEs with overall survival (OS) in cancer drugs to analyze the applications of approved cancer drugs with SEs in Mexico and to apply the validation framework proposed by the Institute for Quality and Efficiency in Health Care (IQWiG).

METHODS

An overview of SRs was conducted according to Cochrane Collaboration methodology. Applications for approved cancer drugs with SEs in Mexico were analyzed. The IQWiG validation framework was applied to evaluate the SEs identified in the overview and in the applications in Mexico.

RESULTS

A total of 85 SRs that assessed 192 SEs for different types of cancer were selected. According to the IQWiG model, only 2.5% of the SEs analyzed in the overview and only one of the applications in Mexico could be used as surrogates for OS because the reliability (methodological quality) of the SRs and the strength of the correlation of SEs with OS was mostly low (92%) and low (correlation coefficient r ≤ 0.7; 50.5%), respectively. Of the total number of cancer drugs approved in Mexico, 19.4% used SEs.

CONCLUSIONS

Most SEs for different types of cancer could not be used as surrogates for OS according to the IQWiG model, and their use for the approval of cancer drugs in Mexico is generally not justified.

Surrogate endpoint evaluation using data from one large global randomized controlled trial

BACKGROUND

Robust identification of surrogate endpoints can help accelerate the development of pharmacotherapies for diseases traditionally evaluated using true endpoints associated with prolonged follow-up. The meta-analysis-based surrogate endpoint evaluation (SEE) integrates data from multiple, usually smaller, trials to statistically confirm a surrogate endpoint as a robust proxy for the true endpoint. To test the applicability of SEE when only a single, larger trial is available, we analysed the cardiovascular (CV) survival endpoint from the large multinational trial LEADER (9340 subjects) that confirmed the CV safety of a diabetes drug (liraglutide). We evaluated if using country as a trial unit adequately facilitated the meta-analysis and calculation of R² by country group.

METHODS

Data were grouped by country, ensuring at least 30 CV deaths (497 in total) in each of the nine resulting by-country groups. In a two-step SEE on the grouped dataset, we first fitted the group-specific Cox proportional hazard models; next, on the trial-level, we regressed the estimated hazard ratio (HR; liraglutide vs placebo) of the true endpoints (CV death: 497 events, or all-cause death: 828 events) on the HR of the surrogate endpoint (major CV adverse event [MACE]: 1302 events) and derived the group-specific R² and its 95% confidence interval (CI).

RESULTS

Group-level surrogacy of MACE was supported for CV death but not for all-cause death, with [Formula: see text] values of 0.85 [0.63;1.00]_{95% CI} and 0.23 [0.00;0.67]_{95% CI}, respectively. Sensitivity analyses using different grouping approaches (e.g. grouping by region) corroborated the robustness of the conclusions as well as the appropriateness of the data-grouping approaches.

CONCLUSIONS

We derived a specific grouping approach to successfully apply SEE on data from a single trial. This may allow for the statistically robust identification and validation of surrogate endpoints based on the abundance of large monolithic outcome trials conducted as part of drug development programmes in, for example, diabetes.

Validity of Surrogate Endpoints and Their Impact on Coverage Recommendations: A Retrospective Analysis across International Health Technology Assessment Agencies

BACKGROUND

Surrogate endpoints (i.e., intermediate endpoints intended to predict for patient-centered outcomes) are increasingly common. However, little is known about how surrogate evidence is handled in the context of health technology assessment (HTA).

OBJECTIVES

1) To map methodologies for the validation of surrogate endpoints and 2) to determine their impact on acceptability of surrogates and coverage decisions made by HTA agencies.

METHODS

We sought HTA reports where evaluation relied on a surrogate from 8 HTA agencies. We extracted data on the methods applied for surrogate validation. We assessed the level of agreement between agencies and fitted mixed-effects logistic regression models to test the impact of validation approaches on the agency's acceptability of the surrogate endpoint and their coverage recommendation.

RESULTS

Of the 124 included reports, 61 (49%) discussed the level of evidence to support the relationship between the surrogate and the patient-centered endpoint, 27 (22%) reported a correlation coefficient/association measure, and 40 (32%) quantified the expected effect on the patient-centered outcome. Overall, the surrogate endpoint was deemed acceptable in 49 (40%) reports (k-coefficient 0.10, P = 0.004). Any consideration of the level of evidence was associated with accepting the surrogate endpoint as valid (odds ratio [OR], 4.60; 95% confidence interval [CI], 1.60-13.18, P = 0.005). However, we did not find strong evidence of an association between accepting the surrogate endpoint and agency coverage recommendation (OR, 0.71; 95% CI, 0.23-2.20; P = 0.55).

CONCLUSIONS

Handling of surrogate endpoint evidence in reports varied greatly across HTA agencies, with inconsistent consideration of the level of evidence and statistical validation. Our findings call for careful reconsideration of the issue of surrogacy and the need for harmonization of practices across international HTA agencies.

Biases in study design, implementation, and data analysis that distort the appraisal of clinical benefit and ESMO-Magnitude of Clinical Benefit Scale (ESMO-MCBS) scoring

Background

The European Society for Medical Oncology-Magnitude of Clinical Benefit Scale (ESMO-MCBS) is a validated, widely used tool developed to score the clinical benefit from cancer medicines reported in clinical trials. ESMO-MCBS scores assume valid research methodologies and quality trial implementation. Studies incorporating flawed design, implementation, or data analysis may generate outcomes that exaggerate true benefit and are not generalisable. Failure to either indicate or penalise studies with bias undermines the intention and diminishes the integrity of ESMO-MCBS scores. This review aimed to evaluate the adequacy of the ESMO-MCBS to address bias generated by flawed design, implementation, or data analysis and identify shortcomings in need of amendment.

Methods

As part of a refinement of the ESMO-MCBS, we reviewed trial design, implementation, and data analysis issues that could bias the results. For each issue of concern, we reviewed the ESMO-MCBS v1.1 approach against standards derived from Helsinki guidelines for ethical human research and guidelines from the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use, the Food and Drugs Administration, the European Medicines Agency, and European Network for Health Technology Assessment.

Results

Six design, two implementation, and two data analysis and interpretation issues were evaluated and in three, the ESMO-MCBS provided adequate protections. Seven shortcomings in the ability of the ESMO-MCBS to identify and address bias were identified. These related to (i) evaluation of the control arm, (ii) crossover issues, (iii) criteria for non-inferiority, (iv) substandard post-progression treatment, (v) post hoc subgroup findings based on biomarkers, (vi) informative censoring, and (vii) publication bias against quality-of-life data.

Conclusion

Interpretation of the ESMO-MCBS scores requires critical appraisal of trials to understand caveats in trial design, implementation, and data analysis that may have biased results and conclusions. These will be addressed in future iterations of the ESMO-MCBS.

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We reviewed trial design, implementation, and data analysis issues that could bias the results of trials.

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These issues could skew the results of ESMO-MCBS scores.

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Six design, two implementation, and two analysis issues were reviewed, and seven shortcomings were identified.

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These issues will be addressed in future versions of the MCBS scale.

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Interpretation of MCBS scores requires critical appraisal of trials.

Exercise-based cardiac rehabilitation for chronic heart failure: the EXTRAMATCH II individual participant data meta-analysis

BACKGROUND

Current national and international guidelines on the management of heart failure (HF) recommend exercise-based cardiac rehabilitation (ExCR), but do not differentiate this recommendation according to patient subgroups.

OBJECTIVES

(1) To obtain definitive estimates of the impact of ExCR interventions compared with no exercise intervention (control) on mortality, hospitalisation, exercise capacity and health-related quality of life (HRQoL) in HF patients; (2) to determine the differential (subgroup) effects of ExCR in HF patients according to their age, sex, left ventricular ejection fraction, HF aetiology, New York Heart Association class and baseline exercise capacity; and (3) to assess whether or not the change in exercise capacity mediates for the impact of the ExCR on final outcomes (mortality, hospitalisation and HRQoL), and determine if this is an acceptable surrogate end point.

DESIGN

This was an individual participant data (IPD) meta-analysis.

SETTING

An international literature review.

PARTICIPANTS

HF patients in randomised controlled trials (RCTs) of ExCR.

INTERVENTIONS

ExCR for at least 3 weeks compared with a no-exercise control, with 6 months' follow-up.

MAIN OUTCOME MEASURES

All-cause and HF-specific mortality, all-cause and HF-specific hospitalisation, exercise capacity and HRQoL.

DATA SOURCES

IPD from eligible RCTs.

REVIEW METHODS

RCTs from the Exercise Training Meta-Analysis of Trials for Chronic Heart Failure (ExTraMATCH/ExTraMATCH II) IPD meta-analysis and a 2014 Cochrane systematic review of ExCR (Taylor RS, Sagar VA, Davies EJ, Briscoe S, Coats AJ, Dalal H, et al. Exercise-based rehabilitation for heart failure. Cochrane Database Syst Rev 2014;4:CD003331).

RESULTS

Out of the 23 eligible RCTs (4398 patients), 19 RCTs (3990 patients) contributed data to this IPD meta-analysis. There was a wide variation in exercise programme prescriptions across included studies. Compared with control, there was no statistically significant difference in pooled time-to-event estimates in favour of ExCR, although confidence intervals (CIs) were wide: all-cause mortality had a hazard ratio (HR) of 0.83 (95% CI 0.67 to 1.04); HF-related mortality had a HR of 0.84 (95% CI 0.49 to 1.46); all-cause hospitalisation had a HR of 0.90 (95% CI 0.76 to 1.06); and HF-related hospitalisation had a HR of 0.98 (95% CI 0.72 to 1.35). There was a statistically significant difference in favour of ExCR for exercise capacity and HRQoL. Compared with the control, improvements were seen in the 6-minute walk test (6MWT) (mean 21.0 m, 95% CI 1.57 to 40.4 m) and Minnesota Living with Heart Failure Questionnaire score (mean -5.94, 95% CI -1.0 to -10.9; lower scores indicate improved HRQoL) at 12 months' follow-up. No strong evidence for differential intervention effects across patient characteristics was found for any outcomes. Moderate to good levels of correlation (R ² _trial > 50% and p > 0.50) between peak oxygen uptake (VO₂peak) or the 6MWT with mortality and HRQoL were seen. The estimated surrogate threshold effect was an increase of 1.6 to 4.6 ml/kg/minute for VO₂peak.

LIMITATIONS

There was a lack of consistency in how included RCTs defined and collected the outcomes: it was not possible to obtain IPD from all includable trials for all outcomes and patient-level data on exercise adherence was not sought.

CONCLUSIONS

In comparison with the no-exercise control, participation in ExCR improved the exercise and HRQoL in HF patients, but appeared to have no effect on their mortality or hospitalisation. No strong evidence was found of differential intervention effects of ExCR across patient characteristics. VO₂peak and 6MWT may be suitable surrogate end points for the treatment effect of ExCR on mortality and HRQoL in HF. Future studies should aim to achieve a consensus on the definition of outcomes and promote reporting of a core set of HF data. The research team also seeks to extend current policies to encourage study authors to allow access to RCT data for the purpose of meta-analysis.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42014007170.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Are Surrogate Endpoints Unbiased Metrics in Clinical Benefit Scores of the ASCO Value Framework?

BACKGROUND

Clinical benefit scores (CBS) are key elements of the ASCO Value Framework (ASCO-VF) and are weighted based on a hierarchy of efficacy endpoints: hazard ratio for death (HR OS), median overall survival (mOS), HR for disease progression (HR PFS), median progression-free survival (mPFS), and response rate (RR). When HR OS is unavailable, the other endpoints serve as "surrogates" to calculate CBS. CBS are computed from PFS or RR in 39.6% of randomized controlled trials. This study examined whether surrogate-derived CBS offer unbiased scoring compared with HR OS-derived CBS.

METHODS

Using the ASCO-VF, CBS for advanced disease settings were computed for randomized controlled trials of oncology drug approvals by the FDA, European Medicines Agency, and Health Canada in January 2006 through December 2017. Mean differences of surrogate-derived CBS minus HR OS-derived CBS assessed the tendency of surrogate-derived CBS to overestimate or underestimate clinical benefit. Spearman's correlation evaluated the association between surrogate- and HR OS-derived CBS. Mean absolute error assessed the average difference between surrogate-derived CBS relative to HR OS-derived CBS.

RESULTS

CBS derived from mOS, HR PFS, mPFS, and RR overestimated HR OS-derived CBS in 58%, 68%, 77%, and 55% of pairs and overall by an average of 5.62 (n=90), 6.86 (n=110), 29.81 (n=101), and 3.58 (n=108), respectively. Correlation coefficients were 0.80 (95% CI, 0.70-0.86), 0.38 (0.20-0.53), 0.20 (0.00-0.38), and 0.01 (-0.18 to 0.19) for mOS-, HR PFS-, mPFS-, and RR-derived CBS, respectively, and mean absolute errors were 11.32, 12.34, 40.40, and 18.63, respectively.

CONCLUSIONS

Based on the ASCO-VF algorithm, HR PFS-, mPFS-, and RR-derived CBS are suboptimal surrogates, because they were shown to be biased and poorly correlated to HR OS-derived CBS. Despite lower weighting than OS in the ASCO-VF algorithm, PFS still overestimated CBS. Simple rescaling of surrogate endpoints may not improve their validity within the ASCO-VF given their poor correlations with HR OS-derived CBS.

Evaluation of Pathologic Complete Response as a Surrogate for Long-Term Survival Outcomes in Triple-Negative Breast Cancer

Background: Pathologic complete response (pCR) is a common efficacy endpoint in neoadjuvant therapy trials for triple-negative breast cancer (TNBC). Previous studies have shown that pCR is strongly associated with improved long-term survival outcomes, including event-free survival (EFS) and overall survival (OS). However, the trial-level associations between treatment effect on pCR and long-term survival outcomes are not well established. This study sought to evaluate these associations by incorporating more recent clinical trials in TNBC. Methods: A literature review identified published randomized controlled trials (RCTs) of neoadjuvant therapy for TNBC that reported results for both pCR and EFS/OS. Meta-regression models were performed to evaluate the association of treatment effect on pCR and EFS/OS. Sensitivity analyses were conducted to assess the impact of divergent study designs. Results: Ten comparisons from 8 RCTs (N=2,478 patients) were identified from the literature review. The log (odds ratio) of pCR was a significant predictor of the log (hazard ratio) of EFS (P=.003), with a coefficient of determination of 0.68 (95% CI, 0.41–0.95). There was a weaker association between pCR and OS (P=.18), with a coefficient of determination of 0.24 (95% CI, 0.01–0.77). Consistent results were found in the exploratory analysis and sensitivity analyses. Conclusions: This is the first study that has shown a trial-level association between pCR and survival outcomes in TNBC. By incorporating the most up-to-date RCTs, this study showed a significant trial-level association between pCR and EFS. A positive association between pCR and OS was also recorded.

Event-Free Survival, a Prostate-Specific Antigen-Based Composite End Point, Is Not a Surrogate for Overall Survival in Men With Localized Prostate Cancer Treated With Radiation

PURPOSE

Recently, we have shown that metastasis-free survival is a strong surrogate for overall survival (OS) in men with intermediate- and high-risk localized prostate cancer and can accelerate the evaluation of new (neo)adjuvant therapies. Event-free survival (EFS), an earlier prostate-specific antigen (PSA)-based composite end point, may further expedite trial completion.

METHODS

EFS was defined as the time from random assignment to the date of first evidence of disease recurrence, including biochemical failure, local or regional recurrence, distant metastasis, or death from any cause, or was censored at the date of last PSA assessment. Individual patient data from trials within the Intermediate Clinical Endpoints in Cancer of the Prostate-ICECaP-database with evaluable PSA and disease follow-up data were analyzed. We evaluated the surrogacy of EFS for OS using a 2-stage meta-analytic validation model by determining the correlation of EFS with OS (patient level) and the correlation of treatment effects (hazard ratios [HRs]) on both EFS and OS (trial level). A clinically relevant surrogacy was defined a priori as an R² ≥ 0.7.

RESULTS

Data for 10,350 patients were analyzed from 15 radiation therapy-based trials enrolled from 1987 to 2011 with a median follow-up of 10 years. At the patient level, the correlation of EFS with OS was 0.43 (95% CI, 0.42 to 0.44) as measured by Kendall's tau from a copula model. At the trial level, the R² was 0.35 (95% CI, 0.01 to 0.60) from the weighted linear regression of log(HR)-OS on log(HR)-EFS.

CONCLUSION

EFS is a weak surrogate for OS and is not suitable for use as an intermediate clinical end point to substitute for OS to accelerate phase III (neo)adjuvant trials of prostate cancer therapies for primary radiation therapy-based trials.

Association Between Fibrosis Stage and Outcomes of Patients With Nonalcoholic Fatty Liver Disease: A Systematic Review and Meta-Analysis

BACKGROUND & AIMS

Biopsy-confirmed liver fibrosis is a prognostic factor for patients with nonalcoholic fatty liver disease (NAFLD). We performed a systematic review to quantify the prognostic value of fibrosis stage in patients with NAFLD and the subgroup of patients with nonalcoholic steatohepatitis (NASH) and to assess the evidence that change in fibrosis stage is a surrogate endpoint.

METHODS

We searched the MEDLINE, Embase, Cochrane Library, and trial registry databases through August 2018 for prospective or retrospective cohort studies of liver-related clinical events and outcomes in adults with NAFLD or NASH. We collected data on mortality (all cause and liver related) and morbidity (cirrhosis, liver cancer, and all liver-related events) by stage of fibrosis, determined by biopsy, for patients with NAFLD or NASH. Using fibrosis stage 0 as a reference population, we calculated fibrosis stage-specific relative risk (RR) and 95% confidence interval (CI) values for mortality and morbidities. We performed fixed-effect and random-effect model meta-analyses. Metaregression was used to examine associations among study design (prospective vs retrospective cohort), overall risk of bias (medium or high), and mean duration of follow-up (in years).

RESULTS

Our meta-analysis included 13 studies, comprising 4428 patients with NAFLD; 2875 of these were reported to have NASH. Compared with no fibrosis (stage 0), unadjusted risk increased with increasing stage of fibrosis (stage 0 vs 4): all-cause mortality RR, 3.42 (95% CI, 2.63-4.46); liver-related mortality RR, 11.13 (95% CI, 4.15-29.84); liver transplant RR, 5.42 (95% CI, 1.05-27.89); and liver-related events RR, 12.78 (95% CI, 6.85-23.85). The magnitude of RR did not differ significantly after adjustment for confounders, including age or sex in the subgroup of NAFLD patients with NASH. Three studies examined the effects of increasing fibrosis on quality of life had inconsistent findings.

CONCLUSIONS

In a systematic review and meta-analysis, we found biopsy-confirmed fibrosis to be associated with risk of mortality and liver-related morbidity in patients with NAFLD, with and without adjustment for confounding factors and in patients with reported NASH. Further studies are needed to assess the association between fibrosis stage and patient quality of life and establish that change in liver fibrosis stage is a valid endpoint for use in clinical trials.

Progression-free survival as a surrogate for overall survival in oncology trials: a methodological systematic review

Background

Progression-free survival (PFS) is a surrogate endpoint widely used for overall survival (OS) in oncology. Validation of PFS as a surrogate must be done for each indication and each intervention. We aimed to identify all studies evaluating the validity of PFS as a surrogate for OS in oncology, and to describe their methodological characteristics.

Methods

We conducted a systematic review by searching MEDLINE via PubMed and the Cochrane Library with no limitation on time, selected relevant studies and extracted data in duplicate on how surrogacy was evaluated (meta-analytic approach, assessment of correlation and level of evaluation).

Results

We identified 91 studies evaluating the validity of PFS as a surrogate for OS in 24 cancer localisations. Although a meta-analytic approach was used in 83 (91%) studies, the methods used to validate PFS as a surrogate of OS were heterogeneous across studies. Of the 47 studies concluding that PFS is a good surrogate for OS, for 15 (32%), there was no quantitative argument for surrogacy.

Conclusions

Although most studies used a meta-analytic approach as recommended, our methodological review highlights heterogeneity in methods and reporting, which stresses the importance of developing and applying clear recommendations in this area.

Achieving equal and timely access to innovative anticancer drugs in the European Union (EU): summary of a multidisciplinary CECOG-driven roundtable discussion with a focus on Eastern and South-Eastern EU countries

The Central European Cooperative Oncology Group (CECOG) and ‘ESMO Open—Cancer Horizons’ roundtable discussion brought together stakeholders from several European Union (EU) countries involved in drug development, drug authorisation and reimbursement or otherwise affected by delayed and unequal access to innovative anticancer drugs. The approval process of drugs is well established and access delays can be caused directly or indirectly by national or regional decision-making processes on reimbursement. The two key aspects for those involved in reimbursement decisions are first the level of evidence required to decide and second pricing, which can be challenging for some innovative oncology compounds, especially in Eastern and South-Eastern European countries. Other important factors include: available healthcare budget; the structure and sophistication of healthcare authorities and health technology assessment processes; societal context and political will. From the point of view of the pharmaceutical industry, better alignment between stakeholders in the process and adaptive pathway initiatives is desirable. Key aspects for patients are improved access to clinical trials, preapproval availability and reports on real-world evidence. Restricted access limits oncologists’ daily work in Eastern and South-Eastern EU countries. The roundtable discussion suggested considering the sequencing of regulatory approval and reimbursement decisions together with more flexible contracting as a possible way forward. The panel concluded that early and regular dialogue between all stakeholders including regulators, payers, patient stakeholders and industry is required to improve the situation.

The use of validated and nonvalidated surrogate endpoints in two European Medicines Agency expedited approval pathways: A cross-sectional study of products authorised 2011-2018

BACKGROUND

In situations of unmet medical need or in the interests of public health, expedited approval pathways, including conditional marketing authorisation (CMA) and accelerated assessment (AA), speed up European Medicines Agency (EMA) marketing authorisation recommendations for medicinal products. CMAs are based on incomplete benefit-risk assessment data and authorisation remains conditional until regulator-imposed confirmatory postmarketing measures are fulfilled. For products undergoing AA, complete safety and efficacy data should be available, and postauthorisation measures may include only standard requirements of risk management and pharmacovigilance plans. In the pivotal trials supporting products assessed by expedited pathways, surrogate endpoints reduce drug development time compared with waiting for the intended clinical outcomes. Whether surrogate endpoints supporting products authorised through CMA and AA pathways reliably predict clinical benefits of therapy has not been studied systematically. Our objectives were to determine the extent to which surrogate endpoints are used and to assess whether their validity had been confirmed according to published hierarchies.

METHODS AND FINDINGS

We used European Public Assessment Reports (EPARs) to identify the primary endpoints in the pivotal trials supporting products authorised through CMA or AA pathways during January 1, 2011 to December 31, 2018. We excluded products that were vaccines, topical, reversal, or bleeding prophylactic agents or withdrawn within the study time frame. Where pivotal trials reported surrogate endpoints, we conducted PubMed searches for evidence of validity for predicting clinical outcomes. We used 2 published hierarchies to assess validity level. Surrogates with randomised controlled trials supporting the surrogate-clinical outcome relationship were rated as 'validated'. Fifty-one products met the inclusion criteria; 26 underwent CMAs, and 25 underwent AAs. Overall, 26 products were for oncology indications, 10 for infections, 8 for genetic disorders, and 7 for other systems disorders. Five products (10%), all AAs, were authorised based on pivotal trials reporting clinical outcomes, and 46 (90%) were authorised based on surrogate endpoints. No studies were identified that validated the surrogate endpoints. Among a total of 49 products with surrogate endpoints reported, most were rated according to the published hierarchies as being 'reasonably likely' (n = 30; 61%) or of having 'biological plausibility' (n = 46; 94%) to predict clinical outcomes. EPARs did not consistently explain the nature of the pivotal trial endpoints supporting authorisations, whether surrogate endpoints were validated or not, or describe the endpoints to be reported in the confirmatory postmarketing studies. Our study has limitations: we may have overlooked relevant validation studies; the findings apply to 2 expedited pathways and may not be generalisable to products authorised through the standard assessment pathway.

CONCLUSIONS

The pivotal trial evidence supporting marketing authorisations for products granted CMA or AA was based dominantly on nonvalidated surrogate endpoints. EPARs and summary product characteristic documents, including patient information leaflets, need to state consistently the nature and limitations of endpoints in pivotal trials supporting expedited authorisations so that prescribers and patients appreciate shortcomings in the evidence about actual clinical benefit. For products supported by nonvalidated surrogate endpoints, postauthorisation measures to confirm clinical benefit need to be imposed by the regulator on the marketing authorisation holders.

Sustained Progression-Free Survival Benefit of Rituximab Maintenance in Patients With Follicular Lymphoma: Long-Term Results of the PRIMA Study

PURPOSE

The PRIMA study (ClinicalTrials.gov identifier: NCT00140582) established that 2 years of rituximab maintenance after first-line immunochemotherapy significantly improved progression-free survival (PFS) in patients with follicular lymphoma compared with observation. Here, we report the final PFS and overall survival (OS) results from the PRIMA study after 9 years of follow-up and provide a final overview of safety.

METHODS

Patients (> 18 years of age) with previously untreated high-tumor-burden follicular lymphoma were nonrandomly assigned to receive one of three immunochemotherapy induction regimens. Responding patients were randomly assigned (stratified by induction regimen, response to induction treatment, treatment center, and geographic region) 1:1 to receive 2 years of rituximab maintenance (375 mg/m², once every 8 weeks), starting 8 weeks after the last induction treatment, or observation (no additional treatment). All patients in the extended follow-up provided their written informed consent (data cutoff: December 31, 2016).

RESULTS

In total, 1,018 patients completed induction treatment and were randomly assigned to rituximab maintenance (n = 505) or observation (n = 513). Consent for the extended follow-up was provided by 607 patients (59.6%) of 1,018 (rituximab maintenance, n = 309; observation, n = 298). After data cutoff, median PFS was 10.5 years in the rituximab maintenance arm compared with 4.1 years in the observation arm (hazard ratio, 0.61; 95% CI, 0.52 to 0.73; P < .001). No OS difference was seen in patients randomly assigned to rituximab maintenance or observation (hazard ratio, 1.04; 95% CI, 0.77 to 1.40; P = .7948); 10-year OS estimates were approximately 80% in both study arms. No new safety signals were observed.

CONCLUSION

Rituximab maintenance after induction immunochemotherapy provides a significant long-term PFS, but not OS, benefit over observation.

Analytic Considerations in Applying a General Economic Evaluation Reference Case to Gene Therapy

The concept of a reference case, first proposed by the US Panel on Cost-Effectiveness in Health and Medicine, has been used to specify the required methodological features of economic evaluations of healthcare interventions. In the case of gene therapy, there is a difference of opinion on whether a specific methodological reference case is required. The aim of this article was to provide a more detailed analysis of the characteristics of gene therapy and the extent to which these characteristics warrant modifications to the methods suggested in general reference cases for economic evaluation. We argue that a completely new reference case is not required, but propose a tailored checklist that can be used by analysts and decision makers to determine which aspects of economic evaluation should be considered further, given the unique nature of gene therapy.

Tumor downstaging as an intermediate endpoint to assess the activity of neoadjuvant systemic therapy in patients with muscle-invasive bladder cancer

BACKGROUND

Achieving a pathologic complete response (pCR) with neoadjuvant chemotherapy (NAC) in patients with muscle-invasive bladder cancer (MIBC) has been associated with improved overall survival (OS). This study was aimed at evaluating the impact of pathologic downstaging (pDS; ie, a pT stage at least 1 stage lower than the pre-NAC cT stage) on the OS of patients with MIBC treated with NAC.

METHODS

The Retrospective International Study of Cancers of the Urothelial Tract (RISC) and the National Cancer Database (NCDB) were queried for cT2-4N0M0 patients treated with NAC. A multivariable Cox model including either pDS or pCR was generated. A nested model was built to evaluate the added value of pDS (excluding patients achieving a pCR) to a model including pCR alone. C indices were computed to assess discrimination. NCDB was used for validation. The treatment effect of NAC versus cystectomy alone in achieving pDS was estimated through an inverse probability-weighted regression adjustment.

RESULTS

Overall, 189 and 2010 patients from the RISC and NCDB cohorts, respectively, were included; pDS and pCR were achieved by 33% and 35% and by 20% and 15% in RISC and NCDB, respectively. In both data sets, pDS and pCR were associated with better OS and C indices. Adding pDS excluding pCR to the model with pCR fit the data better (likelihood ratio, P = .019 for RISC and P < .001 for NCDB), and it yielded better discrimination (incremental C index, 4.2 for RISC and 1.6 for NCDB). The treatment effect of NAC in achieving pDS was 2.07-fold (P < .001) in comparison with cystectomy alone.

CONCLUSIONS

A decrease of at least 1 stage from the cT stage to the pT stage is associated with improved OS in patients with MIBC treated with NAC.

Trends in endpoint selection and result interpretation in advanced non-small cell lung cancer clinical trials published between 2000 and 2012: A retrospective cohort study

Background

The objective of this review was to investigate trends in clinical trial design, specifically, the primary outcomes used, interpretation of results, and the magnitude of the benefits described in phase III controlled clinical trials in the first‐line treatment of patients with advanced non‐small cell lung cancer (NSCLC).

Methods

Seventy‐six trials published between 2000 and 2012 were selected from a total of 122 identified in a structured search.

Results

Overall survival (OS) was evaluated as the primary study endpoint in 50 (65.8%) trials, followed by progression‐free survival (PFS) in 15 (19.7%), and other variables, such as toxicity, quality of life (QoL), and response rate in 11 (14.5%). Ten (66.7%) out of 15 clinical trials using PFS as the primary endpoint were published between 2010 and 2012. Median overall survival (mOS) was 9.90 months (interquartile range: 3.5) with an increase of 0.384 months per year of publication (P < 0.001). A statistically significant improvement in mOS was obtained in only 13 (18.8%) trials. A total of 41 (53.9%) studies concluded that the result was positive. Of these, only 16 (39.1%) showed a statistically significant benefit in OS. QoL was assessed in 46 trials (60.5%) and of these, 10 (21.7%) reported significant improvements.

Conclusions

These findings raise important questions about how clinical benefits are measured in clinical trials in advanced NSCLC. Appropriate clinically relevant outcome variables should be established and validated, and post‐marketing studies should be requested by regulatory authorities to ensure meaningful clinical benefits in OS and QoL.

A Systematic Review and Recommendation for Reporting of Surrogate Endpoint Evaluation Using Meta-analyses

Background

Meta-analysis of randomized controlled trials (RCTs) has been widely conducted for the evaluation of surrogate endpoints in oncology, but little attention has been given to the adequacy of reporting and interpretation. This review evaluated the reporting quality of published meta-analyses on surrogacy evaluation and developed recommendations for future reporting.

Methods

We searched PubMed through August 2017 to identify studies that evaluated surrogate endpoints using the meta-analyses of RCTs in oncology. Both individual patient data (IPD) and aggregate data (AD) meta-analyses were included for the review.

Results

Eighty meta-analyses were identified: 22 used IPD and 58 used AD from multiple RCTs. We observed variability and reporting deficiencies in both IPD and AD meta-analyses, especially on reporting of trial selection, endpoint definition, study and patient characteristics for included RCTs, and important statistical methods and results. Based on these findings, we proposed a checklist and recommendations to improve completeness, consistency, and transparency of reports of meta-analytic surrogacy evaluation. We highlighted key aspects of the design and analysis of surrogate endpoints and presented explanations and rationale why these items should be clearly reported in surrogacy evaluation.

Conclusions

Our reporting of surrogate endpoint evaluation using meta-analyses (ReSEEM) guidelines and recommendations will improve the quality in reporting and facilitate the interpretation and reproducibility of meta-analytic surrogacy evaluation. Also, they should help promote greater methodological consistency and could also serve as an evaluation tool in the peer review process for assessing surrogacy research.

Perspectives to mitigate payer uncertainty in health technology assessment of novel oncology drugs

Reimbursement decisions on new oncology drugs are now often made while uncertainty remains about a drug's risk-benefit profile. One consequence of this is a delay in patient access to valuable new medicines. We share our perspectives on strategies to mitigate sources of uncertainty in the health technology assessment process. These include flexible approaches for evaluating the additional benefit, such as better use of surrogate endpoints and health-related quality of life data, and renewed research efforts to define the optimal target population and generate real-world evidence post-authorisation.

Comparative Assessment of Clinical Benefit Using the ESMO-Magnitude of Clinical Benefit Scale Version 1.1 and the ASCO Value Framework Net Health Benefit Score

PURPOSE

To better understand the European Society for Medical Oncology-Magnitude of Clinical Benefit Scale version 1.1 (ESMO-MCBS v1.1) and the ASCO Value Framework Net Health Benefit score version 2 (ASCO-NHB v2), ESMO and ASCO collaborated to evaluate the concordance between the frameworks when used to assess clinical benefit attributable to new therapies.

METHODS

The 102 randomized controlled trials in the noncurative setting already evaluated in the field testing of ESMO-MCBS v1.1 were scored using ASCO-NHB v2 by its developers. Measures of agreement between the frameworks were calculated and receiver operating characteristic curves used to define thresholds for the ASCO-NHB v2 corresponding to ESMO-MCBS v1.1 categories. Studies with discordant scoring were identified and evaluated to understand the reasons for discordance.

RESULTS

The correlation of the 102 pairs of scores for studies in the noncurative setting is estimated to be 0.68 (Spearman's rank correlation coefficient; overall survival, 0.71; progression-free survival, 0.67). Receiver operating characteristic curves identified thresholds for ASCO-NHB v2 for facilitating comparisons with ESMO-MCBS v1.1 categories. After applying pragmatic threshold scores of 40 or less (ASCO-NHB v2) and 2 or less (ESMO-MCBS v1.1) for low benefit and 45 or greater (ASCO-NHB v2) and 4 to 5 (ESMO-MCBS v1.1) for substantial benefit, 37 discordant studies were identified. Major factors that contributed to discordance were different approaches to evaluation of relative and absolute gain for overall survival and progression-free survival, crediting tail of the curve gains, and assessing toxicity.

CONCLUSION

The agreement between the frameworks was higher than observed in other studies that sought to compare them. The factors that contributed to discordant scores suggest potential approaches to improve convergence between the scales.

CHALLENGES AND METHODOLOGIES IN USING PROGRESSION FREE SURVIVAL AS A SURROGATE FOR OVERALL SURVIVAL IN ONCOLOGY

OBJECTIVES

A primary outcome in oncology trials is overall survival (OS). However, to estimate OS accurately requires a sufficient number of patients to have died, which may take a long time. If an alternative end point is sufficiently highly correlated with OS, it can be used as a surrogate. Progression-free survival (PFS) is the surrogate most often used in oncology, but does not always satisfy the correlation conditions for surrogacy. We analyze the methodologies used when extrapolating from PFS to OS.

METHODS

Davis et al. previously reviewed the use of surrogate end points in oncology, using papers published between 2001 and 2011. We extend this, reviewing papers published between 2012 and 2016. We also examine the reporting of statistical methods to assess the strength of surrogacy.

RESULTS

The findings from 2012 to 2016 do not differ substantially from those of 2001 to 2011: the same factors are shown to affect the relationship between PFS and OS. The proportion of papers reporting individual patient data (IPD), strongly recommended for full assessment of surrogacy, remains low: 33 percent. A wide range of methods has been used to determine the appropriateness of surrogates. While usually adhering to reporting standards, the standard of scholarship appears sometimes to be questionable and the reporting of results often haphazard.

CONCLUSIONS

Standards of analysis and reporting PFS to OS surrogate studies should be improved by increasing the rigor of statistical reporting and by agreeing to a minimum set of reporting guidelines. Moreover, the use of IPD to assess surrogacy should increase.

Will the reformed Cancer Drugs Fund address the most common types of uncertainty? An analysis of NICE cancer drug appraisals

BACKGROUND

One of the functions of the reformed Cancer Drugs Fund in England is as a managed access fund, providing conditional funding for cancer drugs where there is uncertainty in the economic case, and where that uncertainty can be addressed by data collection during two years' use in the NHS. Our study characterises likely sources of such uncertainty, through a review of recent NICE Technology Appraisals.

METHODS

Discussions of uncertainty in NICE Appraisal Committees were extracted from published Single Technology Appraisals of cancer drugs, 2014-2016, and categorised inductively. The location of the comments within the structured Appraisal document was used as a proxy for the degree of concern shown by the Committee.

RESULTS

Twenty-nine appraisals were analysed, of which 23 (79%) were recommended for funding. Six main sources of uncertainty were identified. Immaturity of survival data, and issues relating to comparators, were common sources of uncertainty regardless of degree of concern. Uncertainties relating to quality of life, and the patient population in the trial, were discussed frequently but rarely occurred in the more uncertain appraisals. Concerns with trial design, and cost uncertainty, were less common, but a high proportion contributed to the most uncertain appraisals. Funding decisions were not driven by uncertainty in the evidence base, but by the expected cost per QALY relative to acceptance thresholds, and the resultant level of uncertainty in the decision.

CONCLUSIONS

The reformed CDF is an improvement on its predecessor. However the main types of uncertainty seen in recent cancer appraisals will not readily be resolved solely by 2 years' RWD collection in the reformed CDF; where there are no ongoing trials to provide longer-term data, randomised trials rather than RWD may be needed to fully resolve questions of relative efficacy. Other types of uncertainty, and concerns with generalisability, may be more amenable to the RWD approach, and it is these that we expect to be the focus of data collection arrangements in the reformed CDF.

Progression-free survival as a surrogate endpoint of overall survival in patients with metastatic colorectal cancer

Background

In many clinical trials designed to assess the efficacy of anticancer treatments, overall survival (OS) is often used as a primary endpoint despite its several points of weakness.

Methods

This study evaluated the role of progression-free survival (PFS) in the first three lines of treatment as a potential surrogate endpoint of OS in patients with metastatic colorectal cancer (MCRC). One hundred and twenty patients with MCRC were enrolled in this study. The median PFS of the first-, second-, and third-lines of treatment and the OS were evaluated. The correlation between the time to progression and the OS was analyzed. The median PFS of the three lines of treatment were 8.5, 5, and 3 months, respectively.

Results

The median OS was 32.4 months. A modest correlation was found between the PFS to the first-line treatment with Folfox–avastin and OS. Similar data were obtained with the second-line treatment. However, no correlation was found between the PFS and OS during the third-line treatment. The regression analysis revealed that PFS is predictive of OS.

Conclusion

In brief, the PFS of the first- and second-lines of treatment could be a good candidate as a surrogate endpoint of OS in patients with MCRC.

Do immune checkpoint inhibitors need new studies methodology?

Immune checkpoint inhibitors (ICI) have widely reshaped the treatment paradigm of advanced cancer patients. Although multiple studies are currently evaluating these drugs as monotherapies or in combination, the choice of the most accurate statistical methods, endpoints and clinical trial designs to estimate the benefit of ICI remains an unsolved methodological issue. Considering the unconventional patterns of response or progression [i.e., pseudoprogression, hyperprogression (HPD)] observed with ICI, the application in clinical trials of novel response assessment tools (i.e., iRECIST) able to capture delayed benefit of immunotherapies and/or to quantify tumor dynamics and kinetics over time is an unmet clinical need. In addition, the proportional hazard model and the conventional measures of survival [i.e., median overall or progression free survival (PFS) and hazard ratios (HR)] might usually result inadequate in the estimation of the long-term benefit observed with ICI. For this reason, innovative methodologies such as milestone analysis, restricted mean survival time (RMST), parametric models (i.e., Weibull distribution, weighted log rank test), should be systematically investigated in clinical trials in order to adequately quantify the fraction of patients who are "cured", represented by the tails of the survival curves. Regarding predictive biomarkers, in particular PD-L1 expression, the integration and harmonization of the existing assays are urgently needed to provide clinicians with reliable diagnostic tests and to improve patient selection for immunotherapy. Finally, developing original and high-quality study designs, such as adaptive or basket biomarker enriched clinical trials, included in large collaborative platforms with multiple active sites and cross-sector collaboration, represents the successful strategy to optimally assess the benefit of ICI in the next future.

The assessment and appraisal of regenerative medicines and cell therapy products: an exploration of methods for review, economic evaluation and appraisal

BACKGROUND

The National Institute for Health and Care Excellence (NICE) commissioned a 'mock technology appraisal' to assess whether changes to its methods and processes are needed. This report presents the findings of independent research commissioned to inform this appraisal and the deliberations of a panel convened by NICE to evaluate the mock appraisal.

METHODS

Our research included reviews to identify issues, analysis methods and conceptual differences and the relevance of alternative decision frameworks, alongside the development of an exemplar case study of chimeric antigen receptor (CAR) T-cell therapy for treating acute lymphoblastic leukaemia.

RESULTS

An assessment of previous evaluations of regenerative medicines found that, although there were a number of evidential challenges, none was unique to regenerative medicines or was beyond the scope of existing methods used to conceptualise decision uncertainty. Regarding the clinical evidence for regenerative medicines, the issues were those associated with a limited evidence base but were not unique to regenerative medicines: small non-randomised studies, high variation in response and the intervention subject to continuing development. The relative treatment effects generated from single-arm trials are likely to be optimistic unless it is certain that the historical data have accurately estimated the efficacy of the control agent. Pivotal trials may use surrogate end points, which, on average, overestimate treatment effects. To reduce overall uncertainty, multivariate meta-analysis of all available data should be considered. Incorporating indirectly relevant but more reliable (more mature) data into the analysis can also be considered; such data may become available as a result of the evolving regulatory pathways being developed by the European Medicines Agency. For the exemplar case of CAR T-cell therapy, target product profiles (TPPs) were developed, which considered the 'curative' and 'bridging to stem-cell transplantation' treatment approaches separately. Within each TPP, three 'hypothetical' evidence sets (minimum, intermediate and mature) were generated to simulate the impact of alternative levels of precision and maturity in the clinical evidence. Subsequent assessments of cost-effectiveness were undertaken, employing the existing NICE reference case alongside additional analyses suggested within alternative frameworks. The additional exploratory analyses were undertaken to demonstrate how assessments of cost-effectiveness and uncertainty could be impacted by alternative managed entry agreements (MEAs), including price discounts, performance-related schemes and technology leasing. The panel deliberated on the range of TPPs, evidence sets and MEAs, commenting on the likely recommendations for each scenario. The panel discussed the challenges associated with the exemplar and regenerative medicines more broadly, focusing on the need for a robust quantification of the level of uncertainty in the cost-effective estimates and the potential value of MEAs in limiting the exposure of the NHS to high upfront costs and loss associated with a wrong decision.

CONCLUSIONS

It is to be expected that there will be a significant level of uncertainty in determining the clinical effectiveness of regenerative medicines and their long-term costs and benefits, but the existing methods available to estimate the implications of this uncertainty are sufficient. The use of risk sharing and MEAs between the NHS and manufacturers of regenerative medicines should be investigated further.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Evaluation of disease-free survival as an intermediate metric of overall survival in patients with localized renal cell carcinoma: A trial-level meta-analysis

BACKGROUND

Overall survival (OS) is a critical endpoint in adjuvant trials but requires long durations to events and significant patient resources. In the current study, the authors assessed whether disease-free survival (DFS) can be an early clinical surrogate for OS in the adjuvant setting for localized renal cell carcinoma (RCC).

METHODS

Using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, the authors performed a systematic literature review of PubMed and the American Society of Clinical Oncology, European Society for Medical Oncology, and ClinicalTrial.gov Web sites (1996-2016). Inclusion in the current study required randomized controlled trials (RCTs) of adjuvant systemic therapy for localized RCC after nephrectomy with ≥3 years of outcomes data. Data regarding hazard ratios (HRs) and 5-year event-free rates from Kaplan-Meier estimates were extracted. A trial-level meta-analysis correlated estimates of 5-year DFS and 5-year OS as well as treatment effects (HRs) on these endpoints, weighted by the number of DFS events. R-squared ≥ 0.7 was prespecified as being indicative of a strong correlation and the potential for surrogacy.

RESULTS

Thirteen RCTs encompassing 6473 patients who were treated with a variety of systemic therapies met eligibility. Only a modest correlation was observed between 5-year DFS and 5-year OS rates (R-squared, 0.48; 95% confidence interval, 0.14-0.67) and between treatment effects as measured by DFS and OS HRs (R-squared, 0.44; 95% confidence interval, 0.00-0.69).

CONCLUSIONS

Across RCTs of adjuvant systemic therapy for localized RCC, there was no strong correlation noted between 5-year DFS and 5-year OS rates or between treatment effects on these endpoints. These results highlight the need to identify alternative and more rapid clinical or biologic endpoints to hasten drug development and improve clinical outcomes. Cancer 2018;124:925-33. © 2017 American Cancer Society.

Availability of evidence of benefits on overall survival and quality of life of cancer drugs approved by European Medicines Agency: retrospective cohort study of drug approvals 2009-13

Objective To determine the availability of data on overall survival and quality of life benefits of cancer drugs approved in Europe.Design Retrospective cohort study.Setting Publicly accessible regulatory and scientific reports on cancer approvals by the European Medicines Agency (EMA) from 2009 to 2013.Main outcome measures Pivotal and postmarketing trials of cancer drugs according to their design features (randomisation, crossover, blinding), comparators, and endpoints. Availability and magnitude of benefit on overall survival or quality of life determined at time of approval and after market entry. Validated European Society for Medical Oncology Magnitude of Clinical Benefit Scale (ESMO-MCBS) used to assess the clinical value of the reported gains in published studies of cancer drugs.Results From 2009 to 2013, the EMA approved the use of 48 cancer drugs for 68 indications. Of these, eight indications (12%) were approved on the basis of a single arm study. At the time of market approval, there was significant prolongation of survival in 24 of the 68 (35%). The magnitude of the benefit on overall survival ranged from 1.0 to 5.8 months (median 2.7 months). At the time of market approval, there was an improvement in quality of life in seven of 68 indications (10%). Out of 44 indications for which there was no evidence of a survival gain at the time of market authorisation, in the subsequent postmarketing period there was evidence for extension of life in three (7%) and reported benefit on quality of life in five (11%). Of the 68 cancer indications with EMA approval, and with a median of 5.4 years' follow-up (minimum 3.3 years, maximum 8.1 years), only 35 (51%) had shown a significant improvement in survival or quality of life, while 33 (49%) remained uncertain. Of 23 indications associated with a survival benefit that could be scored with the ESMO-MCBS tool, the benefit was judged to be clinically meaningful in less than half (11/23, 48%).Conclusions This systematic evaluation of oncology approvals by the EMA in 2009-13 shows that most drugs entered the market without evidence of benefit on survival or quality of life. At a minimum of 3.3 years after market entry, there was still no conclusive evidence that these drugs either extended or improved life for most cancer indications. When there were survival gains over existing treatment options or placebo, they were often marginal.

Metastasis-Free Survival Is a Strong Surrogate of Overall Survival in Localized Prostate Cancer

Purpose Adjuvant therapy for intermediate-risk and high-risk localized prostate cancer decreases the number of deaths from this disease. Surrogates for overall survival (OS) could expedite the evaluation of new adjuvant therapies. Methods By June 2013, 102 completed or ongoing randomized trials were identified and individual patient data were collected from 28 trials with 28,905 patients. Disease-free survival (DFS) and metastasis-free survival (MFS) were determined for 21,140 patients from 24 trials and 12,712 patients from 19 trials, respectively. We evaluated the surrogacy of DFS and MFS for OS by using a two-stage meta-analytic validation model by determining the correlation of an intermediate clinical end point with OS and the correlation of treatment effects on both the intermediate clinical end point and OS. Results Trials enrolled patients from 1987 to 2011. After a median follow-up of 10 years, 45% of 21,140 men and 45% of 12,712 men experienced a DFS and MFS event, respectively. For DFS and MFS, 61% and 90% of the patients, respectively, were from radiation trials, and 63% and 66%, respectively, had high-risk disease. At the patient level, Kendall's τ correlation with OS was 0.85 and 0.91 for DFS and MFS, respectively. At the trial level, R² was 0.86 (95% CI, 0.78 to 0.90) and 0.83 (95% CI, 0.71 to 0.88) from weighted linear regression of 8-year OS rates versus 5-year DFS and MFS rates, respectively. Treatment effects-measured by log hazard ratios-for the surrogates and OS were well correlated ( R², 0.73 [95% CI, 0.53 to 0.82] for DFS and 0.92 [95% CI, 0.81 to 0.95] for MFS). Conclusion MFS is a strong surrogate for OS for localized prostate cancer that is associated with a significant risk of death from prostate cancer.

Assessment of clinically relevant bleeding as a surrogate outcome for major bleeding: validation by meta-analysis of randomized controlled trials

Essentials Surrogacy of clinically relevant bleeding (CRB) for major bleeding has never been validated. Our meta-analysis evaluated CRB surrogacy in trials of new versus traditional anticoagulants. Surrogacy was not validated in orthopedic surgery, venous thromboembolism or atrial fibrillation The difficulty in demonstrating the surrogacy may reflect a lack of homogeneity in its definition SUMMARY: Background Clinically relevant bleeding (CRB), comprising major bleeding and clinically relevant non-major bleeding, has been used as a surrogate for major bleeding in most anticoagulant trials. The validity of this surrogate to estimate trade-off between thrombotic and bleeding events in clinical trials was never assessed. Methods We systematically reviewed randomized phase III trials comparing new anticoagulants with the standard of care for venous thromboembolism prevention following major orthopedic surgery, venous thromboembolism (VTE) treatment, or stroke and systemic embolism prevention in atrial fibrillation (AF), and reporting both major bleeding and CRB rates. The validity of CRB as a surrogate for major bleeding was assessed according to the strength of the association between the relative risks of major bleeding and CRB, measured by the use of R2trial and its 95% confidence interval (CI). Results In the postoperative prophylactic setting (13 studies), major bleeding and CRB rates were 1.12% and 3.56%, respectively, and R2trial was 0.69 (95% CI 0.34-0.93). For acute VTE studies (n = 12), major bleeding and CRB rates were 1.87% and 9.07%; the corresponding R2trial values were 0.28 (95% CI 0.01-0.80) and 0.68 (95% CI 0.09-1.00) when only double-blind studies were considered (n = 7). For AF studies (n = 7; 22 strata), major bleeding and CRB rates were 4.82% and 15.3%, and R2trial was 0.59 (95% CI 0.15-0.82). Conclusion Despite an apparent correlation between CRB and major bleeding in major orthopedic surgery, AF, and double-blind acute VTE studies, the wide CIs suggest that CRB might not be an acceptable surrogate outcome in any of these settings.