Progression-Free Survival as a Primary Endpoint in Clinical Trials of Metastatic Colorectal Cancer

Immune checkpoint inhibitor plus chemotherapy as first-line treatment for non-small cell lung cancer with malignant pleural effusion: a retrospective multicenter study

BACKGROUND

Immune checkpoint inhibitors (ICI) combined with chemotherapy are efficacious for treating advanced non-small cell lung cancer (NSCLC); however, the effectiveness of this approach in the malignant pleural effusion (MPE) population is unclear. This study evaluated ICI plus chemotherapy in NSCLC patients with MPE.

METHODS

Patients from 3 centers in China with NSCLC and MPE who received ICI plus chemotherapy (ICI Plus Chemo) or chemotherapy alone (Chemo) between December 2014 and June 2023 were enrolled. Clinical outcomes and adverse events (AEs) were compared.

RESULTS

Of 155 eligible patients, the median age was 61.0 years old. Males and never-smokers accounted for 73.5% and 39.4%, respectively. Fifty-seven and 98 patients received ICI Plus Chemo or Chemo, respectively. With a median study follow-up of 10.8 months, progression-free survival (PFS) was significantly longer with ICI Plus Chemo than with Chemo (median PFS: 7.4 versus 5.7 months; HR = 0.594 [95% CI: 0.403-0.874], P = 0.008). Median overall survival (OS) did not differ between groups (ICI Plus Chemo: 34.2 versus Chemo: 28.3 months; HR = 0.746 [95% CI: 0.420-1.325], P = 0.317). The most common grade 3 or worse AEs included decreased neutrophil count (3 [5.3%] patients in the ICI Plus Chemo group vs. 5 [5.1%] patients in the Chemo group) and decreased hemoglobin (3 [5.3%] versus 10 [10.2%]).

CONCLUSIONS

In patients with untreated NSCLC with MPE, ICI plus chemotherapy resulted in significantly longer PFS than chemotherapy and had a manageable tolerability profile, but the effect on OS may be limited.

Tislelizumab plus chemotherapy versus pembrolizumab plus chemotherapy for the first-line treatment of advanced non-small cell lung cancer: systematic review and indirect comparison of randomized trials

Purpose: Pembrolizumab and tislelizumab have demonstrated significant clinical benefits in first-line treatment for advanced NSCLC. However, no head-to-head clinical trial has ever compared the optimal choice. Therefore, we conducted an indirect comparison to explore the optimal choice for advanced NSCLC combined with chemotherapy. Methods: We conducted a systematic review of randomized trials; the clinical outcomes included overall survival (OS), progression-free survival (PFS), objective response rate (ORR), and adverse events (AEs). Indirect comparisons between tislelizumab and pembrolizumab were conducted with the Bucher method. Results: Data were abstracted from 6 randomized trials involving more than 2,000 participants. Direct meta-analysis showed that both treatment regimens improved clinical outcomes compared with chemotherapy alone (PFS: hazard ratio (HR)_{tis+chemo/chemo} 0.55, 95% CI 0.45-0.67; HR_{pem+chemo/chemo} 0.53, 95% CI 0.47-0.60; ORR: relative risk (RR)_{tis+chemo/chemo} 1.50, 95% CI 1.32-1.71; RR_{pem+chemo/chemo} 1.89, 95% CI 1.44-2.48). Regarding safety outcomes, tislelizumab and pembrolizumab have a higher risk in the incidence of grade 3 or higher AEs (RR_{tis+chemo/chemo} 1.12, 95% CI 1.03-1.21; RR_{pem+chemo/chemo} 1.13, 95% CI 1.03-1.24). The indirect comparison showed that there was no significant difference between tislelizumab plus chemotherapy and pembrolizumab plus chemotherapy in terms of PFS (HR: 1.04, 95% CI 0.82-1.31), ORR (RR: 0.79, 95% CI 0.59-1.07), the incidence of grade 3 or higher AEs (RR 0.99, 95% CI 0.87-1.12), and AEs leading to death (RR 0.70, 95% CI 0.23-2.09). In progression-free survival subgroup analysis, the results demonstrate no significant differences in PFS by PD-L1 TPS expression level, age, liver metastasis status, and smoking status between tislelizumab plus chemotherapy and pembrolizumab plus chemotherapy. Conclusion: The efficacy and safety of tislelizumab combination chemotherapy were not substantially different from pembrolizumab combination chemotherapy.

Role of Machine Learning in Precision Oncology: Applications in Gastrointestinal Cancers

Gastrointestinal (GI) cancers, consisting of a wide spectrum of pathologies, have become a prominent health issue globally. Despite medical imaging playing a crucial role in the clinical workflow of cancers, standard evaluation of different imaging modalities may provide limited information. Accurate tumor detection, characterization, and monitoring remain a challenge. Progress in quantitative imaging analysis techniques resulted in "radiomics", a promising methodical tool that helps to personalize diagnosis and treatment optimization. Radiomics, a sub-field of computer vision analysis, is a bourgeoning area of interest, especially in this era of precision medicine. In the field of oncology, radiomics has been described as a tool to aid in the diagnosis, classification, and categorization of malignancies and to predict outcomes using various endpoints. In addition, machine learning is a technique for analyzing and predicting by learning from sample data, finding patterns in it, and applying it to new data. Machine learning has been increasingly applied in this field, where it is being studied in image diagnosis. This review assesses the current landscape of radiomics and methodological processes in GI cancers (including gastric, colorectal, liver, pancreatic, neuroendocrine, GI stromal, and rectal cancers). We explain in a stepwise fashion the process from data acquisition and curation to segmentation and feature extraction. Furthermore, the applications of radiomics for diagnosis, staging, assessment of tumor prognosis and treatment response according to different GI cancer types are explored. Finally, we discussed the existing challenges and limitations of radiomics in abdominal cancers and investigate future opportunities.

RATIONALE 311: tislelizumab plus concurrent chemoradiotherapy for localized esophageal squamous cell carcinoma

Definitive chemoradiotherapy is the standard of care for inoperable locoregionally advanced esophageal squamous cell carcinoma (ESCC). Immune checkpoint inhibitors such as anti-PD-1/PD-L1 antibodies have led to a paradigm shift in advanced, metastatic ESCC treatment; however, the effect of incorporating checkpoint inhibitors in the definitive management of ESCC is unclear. Tislelizumab is an anti-PD-1 antibody specifically engineered to minimize FcɣR binding on macrophages to abrogate antibody-dependent phagocytosis, a mechanism of T-cell clearance and potential resistance to anti-PD-1 therapy. The RATIONALE 311 study described here (BGB-A317-311; NCT03957590) is a registrational multicenter, double-blind, placebo-controlled, randomized, Phase III clinical trial designed to evaluate the efficacy and safety of tislelizumab combined with concurrent chemoradiotherapy in patients with inoperable localized ESCC.

Clinical value of 3'-deoxy-3'-[18F]fluorothymidine-positron emission tomography for diagnosis, staging and assessing therapy response in lung cancer

Lung cancer has the highest mortality rate of any tumour type. The main driver of lung tumour growth and development is uncontrolled cellular proliferation. Poor patient outcomes are partly the result of the limited range of effective anti-cancer therapies available and partly due to the limited accuracy of biomarkers to report on cell proliferation rates in patients. Accordingly, accurate methods of diagnosing, staging and assessing response to therapy are crucial to improve patient outcomes. One effective way of assessing cell proliferation is to employ non-invasive evaluation using 3'-deoxy-3'-[¹⁸F]fluorothymidine ([¹⁸F]FLT) positron emission tomography [¹⁸F]FLT-PET. [¹⁸F]FLT, unlike the most commonly used PET tracer [¹⁸F]fluorodeoxyglucose ([¹⁸F]FDG), can specifically report on cell proliferation and does not accumulate in inflammatory cells. Therefore, this radiotracer could exhibit higher specificity in diagnosis and staging, along with more accurate monitoring of therapy response at early stages in the treatment cycle. This review summarises and evaluates published studies on the clinical use of [¹⁸F]FLT to diagnose, stage and assess response to therapy in lung cancer.

Tislelizumab Plus Chemotherapy as First-Line Treatment for Locally Advanced or Metastatic Nonsquamous NSCLC (RATIONALE 304): A Randomized Phase 3 Trial

INTRODUCTION

Tislelizumab, an anti-programmed cell death protein-1 antibody, was specifically engineered to minimize FcɣR macrophage binding to abrogate antibody-dependent phagocytosis. Compared with chemotherapy alone, tislelizumab plus chemotherapy may improve clinical outcomes in patients with advanced nonsquamous NSCLC (nsq-NSCLC).

METHODS

In this open-label phase 3 trial (RATIONALE 304; NCT03663205), patients with histologically confirmed stage IIIB or IV nsq-NSCLC were randomized (2:1) to receive either arm A: tislelizumab plus platinum (carboplatin or cisplatin) and pemetrexed every 3 weeks (Q3Ws) or arm B: platinum and pemetrexed alone Q3W during induction treatment, followed by intravenous maintenance pemetrexed Q3W. The primary end point was progression-free survival (PFS) assessed by an independent review committee; clinical response and safety and tolerability were secondary end points.

RESULTS

Overall, 332 patients (n = 222 [A]; n = 110 [B]) received treatment. With a median study follow-up of 9.8 months, PFS was significantly longer with tislelizumab plus chemotherapy compared with chemotherapy alone (median PFS: 9.7 versus 7.6 mo; hazard ratio = 0.645 [95% confidence interval: 0.462-0.902], p = 0.0044). In addition, response rates were higher and response duration was longer with combination therapy versus chemotherapy alone. Hematologic adverse events (AEs) were common in both treatment arms; the most reported AEs were grades 1 to 2 in severity. The most common grade greater than or equal to 3 AEs were associated with chemotherapy and included neutropenia (44.6% [A]; 35.5% [B]) and leukopenia (21.6% [A]; 14.5% [B]).

CONCLUSIONS

Addition of tislelizumab to chemotherapy resulted in significantly prolonged PFS, higher response rates, and longer response duration compared with chemotherapy alone, identifying a new potential option for first-line treatment of advanced nsq-NSCLC irrespective of disease stage.

Tislelizumab Plus Chemotherapy vs Chemotherapy Alone as First-line Treatment for Advanced Squamous Non-Small-Cell Lung Cancer: A Phase 3 Randomized Clinical Trial

Question

Can tislelizumab in combination with chemotherapy offer superior clinical benefit compared with chemotherapy alone as first-line treatment for patients with advanced squamous non–small-cell lung cancer?

Findings

In this phase 3 randomized clinical trial, tislelizumab plus chemotherapy resulted in significant improvement of progression-free survival and objective response rates compared with chemotherapy alone and demonstrated a manageable safety/tolerability profile. In exploratory analyses, neither progression-free survival nor objective response rates were significantly associated with programmed cell death 1 ligand 1 expression.

Meaning

The results of this trial suggest that tislelizumab in combination with chemotherapy is an appropriate first-line treatment option in patients with advanced squamous non–small-cell lung cancer.

Importance

This study demonstrates that tislelizumab in combination with chemotherapy is associated with improved progression-free survival (PFS) in patients with advanced squamous non–small-cell lung cancer (sq-NSCLC).

Objective

To assess the efficacy and safety/tolerability of tislelizumab plus chemotherapy vs chemotherapy alone as first-line treatment for patients with advanced sq-NSCLC.

Design, Setting, and Participants

This open-label, randomized phase 3 clinical trial was conducted at 46 sites in China between July 2018 and June 2019 and included patients with treatment-naive, histologically confirmed stage IIIB/IV sq-NSCLC. The data cutoff for these analyses was December 6, 2019; data extraction occurred on January 7, 2020.

Interventions

Patients were randomized (1:1:1) to receive 1 of the following regimens intravenously on a 21-day cycle: tislelizumab (200 mg, day 1) plus paclitaxel (175 mg/m², day 1) and carboplatin (area under the concentration of 5, day 1) (arm A); tislelizumab plus nab-paclitaxel (100 mg/m², days 1, 8, and 15) and carboplatin (arm B); and paclitaxel and carboplatin (arm C). Patients were stratified by disease stage and tumor programmed cell death 1 ligand 1 (PD-L1) expression (<1% vs 1%-49% vs ≥50%).

Main Outcomes and Measures

The primary end point was progression-free survival (PFS) assessed by an independent review committee (IRC). Secondary end points included overall survival, investigator-assessed (INV) PFS, IRC-assessed objective response rate (ORR), and IRC-assessed duration of response, as well as the incidence and severity of adverse events (AEs).

Results

Overall, 355 patients (median [range] age, 62 [34-74] years; 330 men [91.7%]) with sq-NSCLC received treatment. After a median study follow-up of 8.6 months (95% CI, 8.1-9.0 months), IRC-assessed PFS was significantly improved with tislelizumab plus chemotherapy (arm A, 7.6 months; arm B, 7.6 months) vs chemotherapy alone (arm C, 5.5 months; hazard ratios were 0.524 (95% CI, 0.370-0.742; P < .001 [A vs C]) and 0.478 (95% CI, 0.336-0.679; P < .001 [B vs C]). Higher IRC-assessed ORR and longer IRC-assessed duration of response were observed in arms A (72.5%; 8.2 months) and B (74.8%; 8.6 months) vs C (49.6%; 4.2 months). No association was observed between PD-L1 expression and IRC-assessed PFS or ORR. Discontinuation of any treatment because of AEs was reported in 15 (12.5%; arm A), 35 (29.7%; arm B), and 18 (15.4%; arm C) patients. In each arm, the most common grade of 3 or greater AE was decreased neutrophil levels, which aligned with known chemotherapy toxic effects. Six treatment-related AEs leading to death occurred; however, no deaths were solely attributed to tislelizumab.

Conclusions and Relevance

In this phase 3 randomized clinical trial, adding tislelizumab to chemotherapy was associated with significantly prolonged IRC-assessed PFS, higher IRC-assessed ORRs, and a manageable safety/tolerability profile in patients with advanced sq-NSCLC, regardless of PD-L1 expression.

Trial Registration

ClinicalTrials.gov Identifier: NCT03594747

Clinical and Regulatory Considerations for the Use of Bevacizumab Biosimilars in Metastatic Colorectal Cancer

Biosimilars - biological medicines highly similar to a licensed reference product (RP) - can mitigate the risk of drug shortages by providing treatment alternatives and, with their lower costs, increase patient access to medication and reduce health care expenditure. However, limited knowledge of biosimilar approval processes and lack of confidence in their quality and efficacy can limit their uptake. Importantly, biosimilars are approved based on tightly controlled regulatory pathways to demonstrate that the physical, chemical, and biological properties of the proposed biosimilar are highly similar to the RP, with no clinically meaningful differences. Initially, a battery of highly sensitive in vitro studies are performed, comparing critical quality attributes between the proposed biosimilar and RP. Subsequently, in vivo pharmacodynamic studies compare the activity and physiologic effects of the biosimilar and RP. Finally, clinical studies are conducted, including a pharmacokinetic equivalence study and a confirmatory comparative clinical trial. The latter is performed in the most sensitive patient population for which the RP is licensed, to provide the greatest possibility of identifying any clinically meaningful differences between the proposed biosimilar and RP. When equivalent safety and efficacy have been demonstrated in one setting, the totality of evidence, together with scientific justification that there are no anticipated differences between the RP and proposed biosimilar in mechanism of action, pharmacokinetics, immunogenicity or toxicity, allows extrapolation into indications where clinical studies were not performed with the proposed biosimilar. Here, we review the approval process for biosimilars, focusing on the licensing of bevacizumab biosimilars and their extrapolation to metastatic colorectal cancer.

The Influence of Pre-Existing Beta-Blockers Use on Survival Outcomes in HER2 Positive Advanced Breast Cancer: Pooled Analysis of Clinical Trial Data

Introduction: Beta-blockers (BB) are commonly used to manage cardiovascular disease and may have benefits in controlling complications of anti-HER2 therapies. This study aimed to evaluate the association of pre-existing BB use with survival outcomes in patients initiating anti-HER2 therapy for advanced breast cancer (ABC). Materials and Methods: Data from clinical trials EMILIA, TH3RESA, MARIANNE, and CLEOPATRA was pooled. Cox proportional analysis was used to assess the association between pre-existing BB use with survival outcomes in patients initiating anti-HER2 therapies. Results: Of the 2,777 patients with HER2 positive ABC, 266 were using a BB at the time of anti-HER2 therapy initiation. BB use was associated with worse overall survival (OS) (adjusted HR = 1.27, 95% CI: 1.04-1.55). Sensitivity analysis in patients with pre-existing cardiovascular disease (CVD) also indicated that BB use was associated with worse OS (1.29, 1.02-1.63). Conclusion: In large high-quality data, BB use at the time of anti-HER2 therapy initiation for ABC was independently associated with worse OS, regardless of CVD status. The finding is contrary to pre-study hypotheses and findings in other BC subtypes. Future research should aim to gain a deeper understanding of the effects of BBs on specific BC subtypes, cancer types, and cancer treatments.

Evaluating Progression-Free Survival as a Surrogate Outcome for Health-Related Quality of Life in Oncology: A Systematic Review and Quantitative Analysis

IMPORTANCE

Progression-free survival (PFS) has become a commonly used outcome to assess the efficacy of new cancer drugs. However, it is not clear if delay in progression leads to improved quality of life with or without overall survival benefit.

OBJECTIVE

To evaluate the association between PFS and health-related quality of life (HRQoL) in oncology through a systematic review and quantitative analysis of published randomized clinical trials. Eligible trials addressed oral, intravenous, intraperitoneal, or intrapleural chemotherapy or biological treatments, and reported PFS or health-related quality of life.

DATA SOURCES

For this systematic review and quantitative analysis of randomized clinical trials of patients with cancer, we searched Medline, Embase, and the Cochrane Central Register of Controlled Trials from January 1, 2000, through May 4, 2016.

STUDY SELECTION

Paired reviewers independently screened citations, extracted data, and assessed risk of bias of included studies.

DATA EXTRACTION AND SYNTHESIS

We examined the association of difference in median PFS duration (in months) between treatment groups with difference in global, physical, and emotional HRQoL scores between groups (standardized to a range of 0-100, with higher scores representing better HRQoL) using weighted simple regressions.

MAIN OUTCOME AND MEASURE

The association between PFS duration and HRQoL.

RESULTS

Of 35 960 records screened, 52 articles reporting on 38 randomized clinical trials involving 13 979 patients across 12 cancer types using 6 different HRQoL instruments were included. The mean (SD) difference in median PFS between the intervention and the control arms was 1.91 (3.35) months. The mean (SD) differences in change of HRQoL adjusted to per-month values were -0.39 (3.59) for the global domain, 0.26 (5.56) for the physical domain, and 1.08 (3.49) for the emotional domain. The slope of the association between the difference in median PFS and the difference in change for global HRQoL (n = 30 trials) was 0.12 (95% CI, -0.27 to 0.52); for physical HRQoL (n = 20 trials) it was -0.20 (95% CI, -0.62 to 0.23); and for emotional HRQoL (n = 13 trials) it was 0.78 (95% CI, -0.05 to 1.60).

CONCLUSIONS AND RELEVANCE

We failed to find a significant association between PFS and HRQoL in cancer clinical trials. These findings raise questions regarding the assumption that interventions prolonging PFS also improve HRQoL in patients with cancer. Therefore, to ensure that patients are truly obtaining important benefit from cancer therapies, clinical trial investigators should measure HRQoL directly and accurately, ensuring adequate duration and follow-up.

Volumetric Versus Unidimensional Measures of Metastatic Colorectal Cancer in Assessing Disease Response

INTRODUCTION

The purpose of this study was to compare unidimensional (1D/linear) and volumetric (3D) measures of metastatic colorectal cancer (mCRC) at computed tomography (CT) for predicting clinical outcome.

PATIENTS AND METHODS

Analysis of CT images in 105 patients (mean age, 59 years; range, 25-81 years; 45 women, 60 men) receiving treatment for mCRC was performed. Both unidimensional and volumetric measures were obtained on index lesions at 3 time points (baseline/midpoint/post-therapy; mean interval, 4.1 months; median, 3.7 months) by 3 readers using a semi-automated technique. Measurements were summed and compared using best overall response across the 3 time points. Patient response was categorized based on Response Evaluation Criteria In Solid Tumors (RECIST) 1.1 thresholds for unidimensional and volume measures (CR, complete response; PR, partial response; SD, stable disease; PD, progressive disease). Survival data was correlated (mean follow-up, 19.9 ± 17.1 months; median, 14.7 months). Intra/interobserver variability and reproducibility of 1D and 3D measures was assessed. Cox survival and Kaplan-Meier models were constructed and compared.

RESULTS

Cox models and Kaplan-Meier curves for unidimensional versus volumetric assessment were very similar in appearance. Both 1D and 3D measurements effectively separated PD from the SD/PR groups, but neither separated SD from PR well. Volumetric measures showed comparable intra/interobserver variability on Bland-Altman analysis to unidimensional measures across readers using a semi-automated measurement technique. Metastatic site (lung, liver, node, other) did not seem to impact measurement reproducibility.

CONCLUSIONS

Although CT volumetric assessment of metastatic colorectal cancer is fairly reproducible by reader and site using a semi-automated technique, the ability to stratify progressive disease from other disease response categories in terms of survival was similar to unidimensional measurement.

STRATEGIC-1: A multiple-lines, randomized, open-label GERCOR phase III study in patients with unresectable wild-type RAS metastatic colorectal cancer

BACKGROUND

The management of unresectable metastatic colorectal cancer (mCRC) is a comprehensive treatment strategy involving several lines of therapy, maintenance, salvage surgery, and treatment-free intervals. Besides chemotherapy (fluoropyrimidine, oxaliplatin, irinotecan), molecular-targeted agents such as anti-angiogenic agents (bevacizumab, aflibercept, regorafenib) and anti-epidermal growth factor receptor agents (cetuximab, panitumumab) have become available. Ultimately, given the increasing cost of new active compounds, new strategy trials are needed to define the optimal use and the best sequencing of these agents. Such new clinical trials require alternative endpoints that can capture the effect of several treatment lines and be measured earlier than overall survival to help shorten the duration and reduce the size and cost of trials.

METHODS/DESIGN

STRATEGIC-1 is an international, open-label, randomized, multicenter phase III trial designed to determine an optimally personalized treatment sequence of the available treatment modalities in patients with unresectable RAS wild-type mCRC. Two standard treatment strategies are compared: first-line FOLFIRI-cetuximab, followed by oxaliplatin-based second-line chemotherapy with bevacizumab (Arm A) vs. first-line OPTIMOX-bevacizumab, followed by irinotecan-based second-line chemotherapy with bevacizumab, and by an anti-epidermal growth factor receptor monoclonal antibody with or without irinotecan as third-line treatment (Arm B). The primary endpoint is duration of disease control. A total of 500 patients will be randomized in a 1:1 ratio to one of the two treatment strategies.

DISCUSSION

The STRATEGIC-1 trial is designed to give global information on the therapeutic sequences in patients with unresectable RAS wild-type mCRC that in turn is likely to have a significant impact on the management of this patient population. The trial is open for inclusion since August 2013.

TRIAL REGISTRATION

STRATEGIC-1 is registered at Clinicaltrials.gov: NCT01910610, 23 July, 2013. STRATEGIC-1 is registered at EudraCT-No.: 2013-001928-19, 25 April, 2013.

Tumor-induced perturbations of cytokines and immune cell networks

Until recently, the intrinsically high level of cross-talk between immune cells, the complexity of immune cell development, and the pleiotropic nature of cytokine signaling have hampered progress in understanding the mechanisms of immunosuppression by which tumor cells circumvent native and adaptive immune responses. One technology that has helped to shed light on this complex signaling network is the cytokine antibody array, which facilitates simultaneous screening of dozens to hundreds of secreted signal proteins in complex biological samples. The combined applications of traditional methods of molecular and cell biology with the high-content, high-throughput screening capabilities of cytokine antibody arrays and other multiplexed immunoassays have revealed a complex mechanism that involves multiple cytokine signals contributed not just by tumor cells but by stromal cells and a wide spectrum of immune cell types. This review will summarize the interactions among cancerous and immune cell types, as well as the key cytokine signals that are required for tumors to survive immunoediting in a dormant state or to grow and spread by escaping it. Additionally, it will present examples of how probing secreted cell-cell signal networks in the tumor microenvironment (TME) with cytokine screens have contributed to our current understanding of these processes and discuss the implications of this understanding to antitumor therapies.

Evaluation of progression-free survival as a surrogate endpoint for survival in chemotherapy and targeted agent metastatic colorectal cancer trials

Pooled analyses of chemotherapy trials in metastatic colorectal cancer (mCRC) have suggested that progression-free survival (PFS) is a surrogate endpoint for overall survival (OS). However, this has not been evaluated under current standard-of-care regimens of chemotherapy in combination with targeted therapies. We conducted an analysis of published mCRC trials of chemotherapy and targeted therapies from 2000 to evaluate the surrogacy of PFS and response rate (RR) for OS. Study-level data was pooled from 24 randomized mCRC trials that evaluated fluoropyrimidine-based regimens and included trials conducted with targeted agents (panitumumab, cetuximab, bevacizumab, and aflibercept). A total of 69 treatment arms with a sample size of 20,438 patients was included. Linear regression analysis was carried out to estimate the correlation of PFS and RR with OS. The correlation coefficient between PFS HRs and OS HRs was 0.86 for all trials, 0.89 for 12 phase III trials of targeted agents in combination with chemotherapy, 0.95 for 8 first-line phase III trials of targeted agents, and 0.83 for 9 trials of anti-EGFR-targeted agents. In all cases, correlation coefficients between RR and OS HRs were lower than those between PFS HRs and OS HRs (range, 0.42-0.81). In this study-level analysis of randomized mCRC trials of chemotherapy and targeted agents, improvements in PFS are strongly correlated with improvements in OS. This suggests that PFS remains a valid surrogate endpoint for OS with current treatment regimens in the mCRC setting.

Progression-free survival as a surrogate endpoint for median overall survival in metastatic colorectal cancer: literature-based analysis from 50 randomized first-line trials

PURPOSE

To evaluate progression-free survival (PFS) as a potential surrogate endpoint (SEP) for overall survival (OS) in metastatic colorectal cancer (mCRC) with a focus on applicability to trials containing targeted therapy with anti-VEGF- or anti-EGF receptor (EGFR)-directed monoclonal antibodies.

EXPERIMENTAL DESIGN

A systematic literature search of randomized trials of first-line chemotherapy for mCRC reported from January 2000 to January 2012 was conducted. Adjusted weighted linear regression was used to calculate correlations within PFS and OS (endpoints; R(EP)) and between treatment effects on PFS and on OS (treatment effects; R(TE)).

RESULTS

Fifty trials reflecting 22,736 patients met the inclusion criteria. Correlation between treatment effects on PFS and OS and between the endpoints PFS and OS was high across all studies (R(TE) = 0.87, R(EP) = 0.86). This was also observed in chemotherapy-only trials (R(TE) = 0.93, R(EP) = 0.81) but less so for trials containing monoclonal antibodies (R(TE) = 0.47; R(EP) = 0.52). Limiting the analysis to bevacizumab-based studies (11 trials, 3,310 patients) again yielded high correlations between treatment effects on PFS and on OS (R(TE) = 0.84), whereas correlation within PFS and OS was low (R(EP) = 0.45). In 7 trials (1,335 patients) investigating cetuximab- or panitumumab-based studies, contrasting correlations with very wide confidence intervals were observed (R(TE) = 0.28; R(EP) = 0.96).

CONCLUSIONS

PFS showed consistently high correlation with OS of an order that would justify its use as an SEP in chemotherapy regimens. For validation of surrogacy in anti-VEGF and anti-EGFR-directed therapies, further research and a larger set of trials is needed.