Factors affecting the association between overall survival and progression-free survival in clinical trials of first-line treatment for patients with advanced non-small cell lung cancer

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.

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.

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.

[Effectiveness of EGFR-TKIs versus chemotherapy as first-line treatment for advanced non-small cell lung cancer: a meta-analysis]

背景与目的

表皮因子受体酪氨酸激酶抑制剂（epidermal growth factor receptor tyrosine kinase inhibitor, EGFR-TKI）应用于非小细胞肺癌（non-small cell lung cancer, NSCLC）一线治疗取得较好的临床疗效，然而EGFR-TKI一线用药选择仍面临很多问题。本研究应用循证医学的方法对NSCLC患者临床特征及基因突变情况对一线EGFR-TKIs治疗及化疗获益进行分析，以便指导临床用药。

方法

用计算机检索Pubmed、Embase、American Society of Clinical Oncology（ASCO）、European Society for Medical Oncology（ESCO）及生物医学数据库等数据库，寻找出EGFR-TKI与化疗相比一线治疗NSCLC的疗效的随机对照研究（randomized controlled trials, RCT）。对纳入RCT进行资料提取和质量评价，采用Review Manager 5.2软件分析、对比NSCLC患者在TKI治疗中的疗效。

结果

纳入的14项研究，共5, 000例患者。Meta分析结果显示，EGFR基因突变的NSCLC患者，EGFR-TKIs治疗与化疗相比有较好的近期有效率（RR=2.31; 95%CI: 1.88-2.84）和延长无疾病进展时间（progression free survival, PFS）（HR=0.39; 95%CI: 0.30-0.49），总生存时间（overall survival, OS）上两者无明显差异（HR=0.99; 95%CI: 0.84-1.16）。临床选择（亚裔、腺癌、不吸烟）NSCLC患者，EGFR-TKIs一线治疗与化疗相比也有较好的近期有效率（RR=1.30; 95%CI: 1.15-1.47），PFS和OS无差异（HR=0.93; 95%CI: 0.58-1.49）（HR=0.91; 95%CI: 0.81-1.02）。未经选择的患者，一线EGFR-TKIs治疗有效率、PFS与化疗无差异，但OS劣于一线接受化疗患者。

结论

EGFR突变的NSCLC患者一线EGFR-TKIs获益更多；对于不能耐受化疗的亚裔、腺癌、不吸烟患者，推荐一线EGFR-TKIs治疗；未经选择的NSCLC患者一线EGFR-TKIs治疗临床无获益，而且一线EGFR-TKI治疗的OS明显低于一线化疗。