Meta-analyses on progression-free survival as a surrogate endpoint for overall survival in triple-negative breast cancer

Objective response rate and progression-free survival as surrogates for overall survival treatment effect: A meta-analysis across diverse tumour groups and contemporary therapies

BACKGROUND

Overall survival (OS) results from randomized control trials (RCT) provide the strongest evidence for efficacy of anti-cancer treatments but can take a considerable amount of time to mature. Progression free survival (PFS) and objective response rate (ORR) are used as an early surrogate of OS treatment effect however their validity remains unclear. Our study aims to comprehensively evaluate ORR and PFS as surrogates for OS treatment effect across tumor groups and treatment types.

MATERIAL AND METHODS

Phase 3 RCTs in solid malignancies that reported OS/PFS and ORR published between 1st of January 2010 and 30th of June 2022 were evaluated. The relationship of surrogate endpoints and OS treatment effect was assessed via weighted linear regression. The coefficient of determination (R2) quantified the fit of the regression model.

RESULTS

675 phase 3 RCT comprising of 350 112 patients were analysed. ORR (R2 of 0.10) and PFS (R2 of 0.38) were poor surrogate markers of OS treatment effect. The strength of surrogacy differed within treatment and tumour groups. PFS had the highest R2 for chemotherapy (0.56) and lowest for targeted therapy (0.40). PFS had the highest level of surrogacy for melanoma (R2 = 0.72) and pancreatic cancer (R2 = 0.70) compared to other tumour groups. Importantly ORR and PFS were also poorly correlated to each other (R2 = 0.33).

CONCLUSIONS

ORR and PFS were poor trial-level surrogate markers of OS. The surrogacy performance of ORR and PFS differed by treatment and malignancy sub-type.

Surrogate endpoints for HTA decisions of breast cancer drugs: utility and pitfalls

PURPOSE OF REVIEW

Health technology assessment (HTA) of cancer drugs is important to identify whether drugs should be publicly funded. With increasing use of surrogate end points in clinical trials including breast cancer, a review of literature was done to synthesize evidence for validation of these surrogate end points and their potential role in HTA decisions pertaining to breast cancer.

FINDINGS

Disease free survival (DFS) in human epidermal receptor 2 (HER2) positive early breast cancer remains the only validated surrogate end point. Other surrogate end points like pathological complete response (pCR) and event free survival (EFS) in early breast cancer (EBC) and objective response rate (ORR) and progression free survival (PFS) in advanced disease have not been validated for overall survival (OS). Moreover, surrogate end points for quality of life (QOL) have not been established and drugs that improve PFS can have detrimental effect on QOL. End points like pCR have excellent prognostic utility in individual patients but have weak correlation with survival at trial level.

SUMMARY

Most surrogate end points used in breast cancer do not predict OS or QOL which makes it challenging to use them for decisions regarding public funding of cancer drugs. These findings are relevant to HTA agencies prior to making drug reimbursement decisions.

Pyrotinib versus placebo in combination with trastuzumab and docetaxel as first line treatment in patients with HER2 positive metastatic breast cancer (PHILA): randomised, double blind, multicentre, phase 3 trial

OBJECTIVE

To assess the efficacy and safety of pyrotinib (an irreversible pan-HER (human epidermal growth factor receptor) inhibitor), trastuzumab, and docetaxel compared with placebo, trastuzumab, and docetaxel for untreated HER2 positive metastatic breast cancer.

DESIGN

Randomised, double blind, placebo controlled, multicentre, phase 3 trial.

SETTING

40 centres in China between 6 May 2019 and 17 January 2022.

PARTICIPANTS

590 female patients (median age 52 (interquartile range 46-58) years) with untreated HER2 positive metastatic breast cancer.

INTERVENTIONS

Eligible patients were randomised 1:1 to receive either oral pyrotinib (400 mg once daily) or placebo, both combined with intravenous trastuzumab (8 mg/kg in cycle 1 and 6 mg/kg in subsequent cycles) and docetaxel (75 mg/m2) on day 1 of each 21 day cycle. Randomisation was stratified by treatment history of trastuzumab in the (neo)adjuvant setting and hormone receptor status. Patients, investigators, and the sponsor's study team were masked to treatment assignment.

MAIN OUTCOME MEASURES

The primary endpoint was progression-free survival as assessed by the investigator.

RESULTS

Of the 590 randomised patients, 297 received pyrotinib, trastuzumab, and docetaxel treatment (pyrotinib group), and 293 received placebo, trastuzumab, and docetaxel treatment (placebo group). At data cut-off on 25 May 2022, the median follow-up was 15.5 months. The median progression-free survival according to the investigator was significantly longer in the pyrotinib group than in the placebo group (24.3 (95% confidence interval 19.1 to 33.0) months versus 10.4 (9.3 to 12.3) months; hazard ratio 0.41 (95% confidence interval 0.32 to 0.53); one sided P<0.001). Treatment related adverse events of grade 3 or higher were reported in 267 (90%) of the 297 patients in the pyrotinib group and 224 (76%) of the 293 patients in the placebo group. No treatment related deaths occurred in the pyrotinib group, and one (<1%; diabetic hyperosmolar coma) treatment related death occurred in the placebo group. Survival and toxicities are still under assessment with longer follow-up.

CONCLUSIONS

Pyrotinib, trastuzumab, and docetaxel showed superiority by significantly improving progression-free survival compared with placebo, trastuzumab, and docetaxel in patients with untreated HER2 positive metastatic breast cancer. The toxicity was manageable. The findings support this dual anti-HER2 regimen as an alternative first line treatment option in this patient population.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03863223.

Molecular imaging as biomarker for treatment response and outcome in breast cancer

Molecular imaging, such as positron emission tomography (PET), is increasingly used as biomarker to predict and assess treatment response in breast cancer. The number of biomarkers is expanding with specific tracers for tumour characteristics throughout the body and this information can be used to aid the decision-making process. These measurements include metabolic activity using [18F]fluorodeoxyglucose PET ([18F]FDG-PET), oestrogen receptor (ER) expression using 16α-[18F]Fluoro-17β-oestradiol ([18F]FES)-PET and human epidermal growth factor receptor 2 (HER2) expression using PET with radiolabelled trastuzumab (HER2-PET). In early breast cancer, baseline [18F]FDG-PET is frequently used for staging, but limited subtype-specific data reduce its usefulness as biomarker for treatment response or outcome. Early metabolic change on serial [18F]FDG-PET is increasingly used in the neo-adjuvant setting as dynamic biomarker to predict pathological complete response to systemic therapy, potentially allowing de-intensification or step-up intensification of treatment. In the metastatic setting, baseline [18F]FDG-PET and [18F]FES-PET can be used as biomarker to predict treatment response, in triple-negative and ER-positive breast cancer, respectively. Metabolic progression on repeated [18F]FDG-PET appears to precede progressive disease on standard evaluation imaging; however, subtype-specific studies are limited and more prospective data are needed before implementation in clinical practice. Even though (repeated) [18F]FDG-PET, [18F]FES-PET and HER2-PEt all show promising results as biomarkers to predict therapy response and outcome, for eventual integration into clinical practice, future studies will have to clarify at what timepoint this integration has to optimally take place.

Correlation between pathologic complete response, event-free survival/disease-free survival and overall survival in neoadjuvant and/or adjuvant HR+/HER2-breast cancer

Purpose

The study's purpose was to evaluate the correlation between overall survival (OS) and its potential surrogate endpoints: pathologic complete response (pCR) and event-free survival (EFS)/disease-free survival (DFS) in neoadjuvant and/or adjuvant HR+/HER2- breast cancer.

Methods

Systematic search was performed in MEDLINE, EMBASE, Cochrane Library databases and other relevant sources to identify literature that have reported outcomes of interest in the target setting. The strength of correlation of EFS/DFS with OS, pCR with OS, and pCR with EFS/DFS was measured using Pearson's correlation coefficient (r) based on weighted regression analysis. For Surrogate Endpoint-True Endpoint pairs where correlation was found to be moderate, surrogate threshold effect (STE) was estimated using a mixed-effects model. Sensitivity analyses were conducted on the scale and weights used and removing outlier data.

Results

Moderate correlation was observed of relative measures [log(HR)] of EFS/DFS and OS (r = 0.91; 95% CI: 0.83, 0.96, p < 0.0001). STE for HR_EFS/DFS was estimated to be 0.73. Association between EFS/DFS at 1, 2 and 3 years with OS at 4- and 5-year landmarks was moderate. Relative treatment effects of pCR and EFS/DFS were not strongly associated (r: 0.24; 95% CI: -0.63, 0.84, p = 0.6028). Correlation between pCR and OS was either not evaluated due to inadequate sample size (relative outcomes) or weak (absolute outcomes). Results obtained in the sensitivity analyses were similar to base scenario.

Conclusion

EFS/DFS were moderately correlated with OS in this trial-level analysis. They may be considered as valid surrogates for OS in HR+/HER2- breast cancer.

Assessment of the clinical and cost-effectiveness evidence in the reimbursement decisions of new cancer drugs

BACKGROUND

This study aimed to describe the clinical and cost-effectiveness evidence supporting reimbursement decisions of new cancer drugs and analyze the influence of trial characteristics and the cost per quality-adjusted life years (QALYs) on the likelihood of reimbursement in Sweden.

PATIENTS AND METHODS

Data were extracted from all appraisal dossiers for new cancer drugs seeking reimbursement in Sweden and claiming added therapeutical value between the years 2010 and 2020. The data were analyzed using descriptive statistics, and logistic regression models were also used with the cost per QALY, study design, comparator, and evidence on final outcomes in the clinical trials as predictors of reimbursement.

RESULTS

All 60 included appraisals were based on trial evidence that assessed at least one final outcome (overall survival [OS] or quality of life [QoL]), although rarely as a primary outcome. Of the appraisals with a final decision (n = 58), 79% were approved for reimbursement. Among the reimbursed drugs, only half had trial evidence demonstrating improved OS or QoL. Only one drug had trial evidence supporting improvements in both OS and QoL. The average cost per QALY for reimbursed cancer drugs was estimated to be 748 560 SEK (€73 583). A higher cost per QALY was found to decrease the likelihood of reimbursement by 9.4% for every 100 000 SEK (€9830) higher cost per QALY (P = 0.03). For cost-effectiveness models without direct evidence of improvements in final outcomes, a larger QALY gain was observed compared with those with evidence mainly relying on intermediate and surrogate outcomes.

CONCLUSIONS

There are substantial uncertainties in the clinical and cost-effectiveness evidence underlying reimbursement decisions of new cancer drugs. Decision makers should be cautious of the limited evidence on patient-centered outcomes and the implications of allocating resources to expensive treatments with uncertain value for money.

Progression-Free Survival and Time to Progression as Potential Surrogate Endpoints for Overall Survival in Chemoradiotherapy Trials in Limited-Stage Small-Cell Lung Cancer: A Systematic Review and Meta-Analysis

Purpose

To investigate whether progression-free survival (PFS) or time to progression (TTP) could be a valid surrogate endpoint for overall survival (OS) in patients with limited-stage small-cell lung cancer (LS-SCLC) receiving combined chemoradiotherapy.

Methods

Literature searching was performed in PubMed, Embase, and The Cochrane Library up to 2021. Prediction models were firstly established using data from phase III randomized controlled trials (RCTs) and then externally validated in phase II and retrospective studies. Correlation analysis was evaluated by a weighted linear regression model at both trial and arm levels. Cross-validation was performed to assess the consistency and robustness of the established models.

Results

37 studies, including 15 phase III RCTs, 12 phase II studies, and 10 retrospective studies, were selected in the final analysis. In trial-level surrogacy, a very good correlation was observed between hazard ratios (HRs) of PFS/TTP and OS (R2 = 0.783, 95% CI 0.771–0.794). In arm-level surrogacy, very good correlations were also observed between 2-year (R2 = 0.823, 95% CI 0.814–0.832), 3-year (R2 = 0.843, 95% CI 0.833–0.850), 5-year (R2 = 0.852, 95% CI 0.843–0.859) PFS/TTP, and 5-year OS. An excellent correlation was observed between 4-year PFS/TTP and 5-year OS (R2 = 0.906, 95% CI 0.901–0.910). Cross-validation demonstrated reasonable overall consistency. External validation in phase II and retrospective studies showed good agreement (R2, 0.728–0.824).

Conclusions

PFS/TTP was a valid surrogate endpoint for OS in patients with LS-SCLC receiving combined chemoradiotherapy. The finding provides high-level evidence to support PFS/TTP as the primary endpoint in clinical trials so as to speed up introducing novel agents to the treatment of LS-SCLC.

Identification of novel genes for triple-negative breast cancer with semiparametric gene-based analysis

Triple-negative breast cancer (TNBC) is generally considered an aggressive breast cancer subtype associated with poor prognostic outcomes. Up to now, the molecular and cellular mechanisms underlying TNBC pathology have not been fully understood. In this manuscript, we propose a novel semiparametric model with kernel for gene-based analysis with a breast cancer GWAS data. The software of SPMGBA (semiparametric method for gene-based analysis) in MATLAB is available at GitHub (https://github.com/zliu3/SPMGBA). Genetic signatures associated with breast cancer are discovered. We further validate the prognostic power of the identified genes with a large cohort of expression data from the European Genome-Phenome Archive, and discover that SEL1L is associated with the overall survival of TNBC with the p-value of .0002. We conclude that gene SEL1L is down-regulated in TNBC and the expression of SEL1L is positively associated with patient survival.

Reforms of regulatory pathways for approval of new antineoplastic drugs in Japan from 2004 to 2019 and accompanying changes in pivotal clinical trial designs

Background The Japanese Pharmaceuticals and Medical Devices Agency (PMDA) was established in 2004. Since then, various pieces of legislation, notices, and guidelines have been issued, and the regulatory approval pathways for domestic drugs have been diversified. However, the effects of these measures have not been fully examined. We examined the impact of these measures on the approval of antineoplastic drugs and the design of pivotal clinical trials for efficacy assessment by the PMDA. Methods We collected data on the antineoplastic drugs approved by the PMDA in fiscal years 2004-2019. We extracted the approval review pathways and the pivotal clinical trial designs from the PMDA review reports, and analyzed them to identify patterns. Results In total, 387 indications in oncology were approved by the PMDA in fiscal years 2004-2019, or 365 indications excluding multiple regulatory pathways. The number of approved indications generally increased year on year (p < 0.001). The largest number of approved indications was under the Orphan Drug Designation (31%, 114/365) and this continues to increase (p < 0.001). In the 288 indications for which clinical trial data were submitted for review, the pivotal clinical trial designs changed significantly (p < 0.001) after the guideline on clinical evaluation for antineoplastic drugs was revised in 2006. Conclusion The number of indications in oncology approved by the PMDA has been increasing over the past 16 years, alongside changes in regulatory pathways. The 2006 guideline on clinical evaluation had a particular impact on pivotal clinical trial designs.

Progression-free survival in oncological clinical studies: Assessment time bias and methods for its correction

Progression-free survival (PFS) is a frequently used endpoint in oncological clinical studies. In case of PFS, potential events are progression and death. Progressions are usually observed delayed as they can be diagnosed not before the next study visit. For this reason potential bias of treatment effect estimates for progression-free survival is a concern. In randomized trials and for relative treatment effects measures like hazard ratios, bias-correcting methods are not necessarily required or have been proposed before. However, less is known on cross-trial comparisons of absolute outcome measures like median survival times. This paper proposes a new method for correcting the assessment time bias of progression-free survival estimates to allow a fair cross-trial comparison of median PFS. Using median PFS for example, the presented method approximates the unknown posterior distribution by a Bayesian approach based on simulations. It is shown that the proposed method leads to a substantial reduction of bias as compared to estimates derived from maximum likelihood or Kaplan-Meier estimates. Bias could be reduced by more than 90% over a broad range of considered situations differing in assessment times and underlying distributions. By coverage probabilities of at least 94% based on the credibility interval of the posterior distribution the resulting parameters hold common confidence levels. In summary, the proposed approach is shown to be useful for a cross-trial comparison of median PFS.

Prognostic value of 18F-FDG PET and PET/CT for assessment of treatment response to neoadjuvant chemotherapy in breast cancer: a systematic review and meta-analysis

Background

We performed a systematic review and meta-analysis to evaluate the prognostic significance of ¹⁸F-FDG PET and PET/CT for evaluation of responses to neoadjuvant chemotherapy (NAC) in breast cancer patients.

Methods

We searched PubMed, Embase, and the Cochrane Library databases until June 2020 to identify studies that assessed the prognostic value of ¹⁸F-FDG PET scans during or after NAC with regard to overall (OS) and disease-free survival (DFS). Hazard ratios (HRs) and their 95% confidence intervals (CIs) were pooled meta-analytically using a random-effects model.

Results

Twenty-one studies consisting of 1630 patients were included in the qualitative synthesis. Twelve studies investigated the use of PET scans for interim response evaluation (during NAC) and 10 studies assessed post-treatment PET evaluation (after NAC). The most widely evaluated parameter distinguishing metabolic responders from poor responders on interim or post-treatment PET scans was %ΔSUVmax, defined as the percent reduction of SUVmax compared to baseline PET, followed by SUVmax and complete metabolic response (CMR). For the 17 studies included in the meta-analysis, the pooled HR of metabolic responses on DFS was 0.21 (95% confidence interval [CI], 0.14–0.32) for interim PET scans and 0.31 (95% CI, 0.21–0.46) for post-treatment PET scans. Regarding the influence of metabolic responses on OS, the pooled HRs for interim and post-treatment PET scans were 0.20 (95% CI, 0.09–0.44) and 0.26 (95% CI, 0.14–0.51), respectively.

Conclusions

The currently available literature suggests that the use of ¹⁸F-FDG PET or PET/CT for evaluation of response to NAC provides significant predictive value for disease recurrence and survival in breast cancer patients and might allow risk stratification and guide rational management.

Differential levels of Alpha-1-inhibitor III, Immunoglobulin heavy chain variable region, and Hypertrophied skeletal muscle protein GTF3 in rat mammary tumorigenesis

Early detection of breast cancer can be best facilitated by the development of precancerous markers. Serum proteins being the sensitive signatures, can be the ideal choice. We previously demonstrated the reduced levels of two serum proteins at a very early stage of tumorigenesis in a breast cancer model, developed in Wistar rats by 7,12-dimethylbenz[a]anthracene (DMBA) administration. Here we report the dysregulation of three more proteins in the serum collected at another early stage (15 weeks) of tumorigenesis in the same model. The proteins were identified (as Alpha-1-inhibitor III (Mug1), Immunoglobulin heavy chain variable region (IGHV), and Hypertrophied skeletal muscle protein GTF3) by MALDI-TOF MS after the screening and fingerprinting of serum samples by one-dimensional (1D) and two-dimensional (2D) electrophoresis respectively. Relative expression analysis of corresponding genes was also carried out, and the results were found as supporting the proteomic findings. In addition, the candidate proteins of the study and their corresponding ribonucleic acids (RNAs) were subjected to homology modelling and docking (using softwares like MODELLER, 3dRNA, Autodock4.0, and GROMACS etc), which revealed the binding sites for carcinogen (DMBA) and its nature of interaction with proteins and RNAs. Moreover, the network analysis by GeneMANIA unraveled the protein/gene functional network in which Mug1, IGHV, and GTF3 are involved. Based on the significant protein and gene expression alterations in early tumorigenesis, these proteins may prove very effective in search for biomarkers for the early detection of mammary cancer. Further, these proteins can also be tried as targets for chemotherapy.