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

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.

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.

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.

The heterogeneity effect of surveillance intervals on progression free survival

Progression-free survival (PFS) is an increasingly important surrogate endpoint in cancer clinical trials. However, the true time of progression is typically unknown if the evaluation of progression status is only scheduled at given surveillance intervals. In addition, comparison between treatment arms under different surveillance schema is not uncommon. Our aim is to explore whether the heterogeneity of the surveillance intervals may interfere with the validity of the conclusion of efficacy based on PFS, and the extent to which the variation would bias the results. We conduct comprehensive simulation studies to explore the aforementioned goals in a two-arm randomized control trial. We introduce three steps to simulate survival data with predefined surveillance intervals under different censoring rate considerations. We report the estimated hazard ratios and examine false positive rate, power and bias under different surveillance intervals, given different baseline median PFS, hazard ratio and censoring rate settings. Results show that larger heterogeneous lengths of surveillance intervals lead to higher false positive rate and overestimate the power, and the effect of the heterogeneous surveillance intervals may depend upon both the life expectancy of the tumor prognoses and the censoring proportion of the survival data. We also demonstrate such heterogeneity effect of surveillance intervals on PFS in a phase III metastatic colorectal cancer trial. In our opinions, adherence to consistent surveillance intervals should be favored in designing the comparative trials. Otherwise, it needs to be appropriately taken into account when analyzing data.

The Validity of Surrogate Endpoints in Sub Groups of Metastatic Colorectal Cancer Patients Defined by Treatment Class and KRAS Status

Background and Aim: Findings from the literature suggest that the validity of surrogate endpoints in metastatic colorectal cancer (mCRC) may depend on a treatments' mechanism of action. We explore this and the impact of Kirsten rat sarcoma (KRAS) status on surrogacy patterns in mCRC. Methods: A systematic review was undertaken to identify randomized controlled trials (RCTs) for pharmacological therapies in mCRC. Bayesian meta-analytic methods for surrogate endpoint evaluation were used to evaluate surrogate relationships across all RCTs, by KRAS status and treatment class. Surrogate endpoints explored were progression free survival (PFS) as a surrogate endpoint for overall survival (OS), and tumour response (TR) as a surrogate for PFS and OS. Results: 66 RCTs were identified from the systematic review. PFS showed a strong surrogate relationship with OS across all data and in subgroups by KRAS status. The relationship appeared stronger within individual treatment classes compared to the overall analysis. The TR-PFS and TR-OS relationships were found to be weak overall but stronger within the Epidermal Growth Factor Receptor + Chemotherapy (EGFR + Chemo) treatment class; both overall and in the wild type (WT) patients for TR-PFS, but not in patients with the mutant (MT) KRAS status where data were limited. Conclusions: PFS appeared to be a good surrogate endpoint for OS. TR showed a moderate surrogate relationship with PFS and OS for the EGFR + Chemo treatment class. There was some evidence of impact of the mechanism of action on the strength of the surrogacy patterns in mCRC, but little evidence of the impact of KRAS status on the validity of surrogate endpoints.

NPY Gene Methylation in Circulating Tumor DNA as an Early Biomarker for Treatment Effect in Metastatic Colorectal Cancer

Despite several limitations, the Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1) are still the gold standard in response evaluation of metastatic colorectal cancer (mCRC). The aim of the present study was to investigate hypermethylated neuropeptide Y circulating tumor DNA (meth-NPY) as an early biomarker for treatment effect and monitoring in 70 mCRC patients receiving first-line treatment in the FOLFOXIRI-Toco trial. Meth-NPY was analyzed using droplet digital PCR, and the response rate was defined as the fraction of patients converting from a baseline detectable level to an undetectable level after the first treatment cycle (responders). A significant increase in meth-NPY was defined as a value with no overlap between the 95% CI of the current and preceding measurement. Progression-free survival (PFS) was significantly longer in meth-NPY responders compared to non-responders, 10.1 and 7.6 months, respectively (p = 0.02, HR = 0.43). Patients with response according to RECIST 1.1 had a PFS of 10.1 compared to 7.3 months for non-responders (p = 0.17, HR = 0.65). A significant increase in meth-NPY was found with a median of 49 days before radiological progression. In conclusion, early meth-NPY response proved superior to response according to RECIST 1.1 with respect to predicting improved PFS. Meth-NPY is an early indicator of progression, allowing treatment reorientation at an earlier timepoint.

Exact Primary Tumor Location in mCRC: Prognostic Value and Predictive Impact on Anti-EGFR mAb Efficacy

Simple Summary

Sidedness of primary tumor is a well-established prognostic marker and is predictive for anti-EGFR efficacy in RAS/BRAF wild-type metastatic colorectal cancer (mCRC) patients. As molecular markers change rather continuously throughout the colon, we ask whether the exact primary tumor location (PTL) is a better prognostic marker than sidedness and predictive for anti-EGFR efficacy in RAS/BRAF wild-type mCRC. We retrospectively analyzed five studies containing various therapy protocols concerning primary tumor location, dividing the colorectal frame into six segments. In our cohort, PTL has a prognostic impact on disease spread and overall survival. Only distal segments benefitted when receiving anti-EGFR containing therapy regarding overall survival. Intermediate segments were indifferent and caecal primaries had a detrimental effect receiving anti-EGFR based therapy. Being a retrospective analysis and challenging the standard of basing anti-EGFR treatment on sidedness in RAS/BRAF wild-type mCRC, future studies are necessary to confirm and further investigate our hypothesis-generating results.

Abstract

Primary tumor sidedness (left vs. right) has prognostic and predictive impact on anti-EGFR agent efficacy and thus management of metastatic colorectal cancer (mCRC). This analysis evaluates the relevance of primary tumor location (PTL) in RAS/BRAF wild-type mCRC patients, when dividing the colorectal frame into six segments. This pooled analysis, performed on a single-patient basis of five randomized first-line therapy trials, evaluates the impact of exact PTL classification on baseline characteristics, prognosis and prediction of anti-EGFR antibody efficacy by chi-square and log-rank tests, the Kaplan–Meier method, Cox and logistic regressions. The PTL was significantly associated with metastatic spread: liver (p = 0.001), lung (p = 0.047), peritoneal (p < 0.001) and lymph nodes (p = 0.048). A multivariate analysis indicated an impact on anti-EGFR agent efficacy in terms of overall survival depending on the exact primary tumor location: from detrimental in caecal (HR 2.63), rather neutral effects in the ascending colon (HR 1.24), right flexure/transverse colon (HR 0.99) and left flexure/descending colon (HR 0.91) to clear benefit in sigmoid (HR 0.71) and rectal (HR 0.58) primaries. Exact primary tumor location affects anti-EGFR antibody efficacy in a rather continuous than a dichotomous fashion in RAS/BRAF wild-type mCRC patients. This perspective might help to support clinical decisions when anti-EGFR antibodies are considered.

Combined inhibition of CXCL12 and PD-1 in MSS colorectal and pancreatic cancer: modulation of the microenvironment and clinical effects

BACKGROUND

Immunotherapy in microsatellite stable colorectal or pancreatic cancer has not shown promising results. It has been hypothesized that targeting immunosuppressive molecules like SDF1-alpha/CXCL12 could contribute to immunotherapy and animal models showed promising results on T cell activation and migration in combination with immune checkpoint inhibition.

METHODS

Here, we describe the successful application of anti-CXCL12 (NOX-A12) in patients with advanced stage pretreated metastatic colorectal and pancreatic cancer (OPERA trial). The treatment consisted of 2 weeks of anti-CXCL12 monotherapy with NOX-A12 followed by combination therapy with pembrolizumab (n=20 patients) until progression or intolerable toxicity had occurred.

RESULTS

The treatment was safe and well tolerated with 83.8% grade I/II, 15.5% grade III and 0.7% grade V adverse events. Of note, for a majority of patients, time on trial treatment was prolonged compared with their last standard treatment preceding trial participation. Systematic serial biopsies revealed distinct patterns of modulation. Tissue and clinical responses were associated with Th1-like tissue reactivity upon CXCL12 inhibition. A downregulation of a cytokine cassette of interleukin (IL)-2/IL-16/CXCL-10 was associated with tumor resistance and furthermore linked to a rare, CXCL12-associated CD14+CD15+promonocytic population. T cells showed aggregation and directed movement towards the tumor cells in responding tissues. Serum analyses detected homogeneous immunomodulatory patterns in all patients, regardless of tissue responses.

CONCLUSIONS

We demonstrate that the combination of CXCL12 inhibition and checkpoint inhibition is safe and grants further exploration of synergistic combinatorial strategies.

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.

Are Quality of Randomized Clinical Trials and ESMO-Magnitude of Clinical Benefit Scale Two Sides of the Same Coin, to Grade Recommendations for Drug Approval?

The approval of a new drug for cancer treatment by the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) is based on positive, well-designed randomized phase III clinical trials (RCTs). However, not all of them are analyzed to support the recommendations. For this reason, there are different scales to quantify and evaluate the quality of RCTs and the magnitude of the clinical benefits of new drugs for treating solid tumors. In this review, we discuss the value of the progression-free survival (PFS) as an endpoint in RCTs and the concordance between it and the overall survival (OS) as a measure of the quality of clinical trial designs. We summarize and analyze the different scales to evaluate the clinical benefits of new drugs such as the The American Society of Clinical Oncology value framework (ASCO-VF-NHB16) and European Society for Medical Oncology Magnitude of Clinical Benefit Scale (ESMO-MCBS) and the concordance between them, focusing on metastatic colorectal cancer (mCRC). We propose several definitions that would help to evaluate the quality of RCT, the magnitude of clinical benefit and the appropriate approval of new drugs in oncology.

Searching for potential surrogate endpoints of overall survival in clinical trials for patients with prostate cancer

BACKGROUND

The purpose of this study was to investigate the correlation between overall survival (OS) and other clinical outcomes in patients with prostate cancer. Further, we conducted subgroup analysis in the correlation of OS.

AIM

This study intended to investigate potential surrogate endpoints of OS for prostate cancer by examining the correlation between OS and the other endpoints.

METHODS

We performed a systematic review through a literature search by computer-based searches of the Medline database (January 1965 and May 2014).

RESULTS

The contents of 115 studies with endpoint as OS were analyzed in our study. Our results showed that 47.8% (55/115) of the studies used progression-free survival as an endpoint besides OS, followed by time to progression (43.5% [50/115]) and PSA response (40.9% [47/115]). Also, the relationship between OS and each surrogate endpoint was examined using the hazard ratio (HR) by a Bayesian hybrid model for random effect multivariate meta-analysis. Our results showed that the endpoint that had the highest correlation with OS was progression-free survival (PFS) with an estimated marginal correlation of 0.939 (95%CI: 0.900, 0.967). Furthermore, our stratified analysis identified PFS in castration-resistant prostate cancer patients (0.937), in sensitive patients (0.932), in none of chemotherapy patients (0.929), in first line of the chemotherapy (0.948), in patients who received no Docetaxel previously (0.942), in both symptomatic and asymptomatic patients (0.950), in patients who received only chemotherapy (0.956), and in phase III (0.960), time to progression (TTP) in castration-resistant prostate cancer (CRPC) patients (0.942), in metastasis patients (0.948), in both symptomatic and asymptomatic patients (0.953), in patients who received only chemotherapy (0.938), and in Phase III (0.927) as endpoints, which showed a lower limit for 95% CI of estimated marginal correlation ≥0.850 with overall survival.

CONCLUSIONS

Our study suggests that PFS is a potential surrogate endpoint of OS in clinical trials for patients with prostate cancer. It also suggests potential surrogate endpoints for CRPC and locally advanced prostate cancer.

Maintenance treatment in advanced HER2-negative gastric cancer

Survival for patients with advanced gastric cancer (GC) remains poor. Systemic chemotherapy which has reached a plateau stays the standard first-line (1L) treatment for advanced human epidermal growth-factor receptor 2 (HER2)-negative GC. To maximize the benefit of 1L treatment, the concept of maintenance treatment is constantly being explored. In advanced HER2-negative GC, current clinical guidelines do not recommend a standard maintenance therapy strategy. In addition to the monotherapy maintenance with fluorouracil after 4-6 cycles of 1L chemotherapy, some agents that are active against novel targets have been evaluated in clinical trials for maintenance treatment. Whereas most of these trials do not reach their primary endpoints, they open new horizons for the 1L treatment of advanced HER2-negative GC. Therefore, we reviewed the clinical trials in the field of maintenance treatment in advanced HER2-negative GC and discussed some of the problems in clinical trials.

Combining Correlated Outcomes and Surrogate Endpoints in a Network Meta-Analysis of Colorectal Cancer Treatments

This study aimed to investigate the efficacy and safety of systemic therapies in the treatment of unresectable advanced or metastatic colorectal cancer. Predicted hazard ratios (HRs) and their 95% credible intervals (CrIs) for overall survival (OS) were calculated from the odds ratio (OR) for the overall response rate and/or HR for progression-free survival using multivariate random effects (MVRE) models. We performed a network meta-analysis (NMA) of 49 articles to compare the efficacy and safety of FOLFOX/FOLFIRI±bevacizumab (Bmab)/cetuximab (Cmab)/panitumumab (Pmab), and FOLFOXIRI/CAPEOX±Bmab. The NMA showed significant OS improvement with FOLFOX, FOLFOX+Cmab, and FOLFIRI+Cmab compared with that of FOLFIRI (HR = 0.84, 95% CrI = 0.73-0.98; HR = 0.76, 95% CrI = 0.62-0.94; HR = 0.80, 95% CrI = 0.66-0.96, respectively), as well as with FOLFOX+Cmab and FOLFIRI+Cmab compared with that of FOLFOXIRI (HR = 0.69, 95% CrI = 0.51-0.94 and HR = 0.73, 95% CrI = 0.54-0.97, respectively). The odds of adverse events grade ≥3 were significantly higher for FOLFOX+Cmab vs. FOLFIRI+Bmab (OR = 2.34, 95% CrI = 1.01-4.66). Higher odds of events were observed for FOLFIRI+Pmab in comparison with FOLFIRI (OR = 2.16, 95% CrI = 1.09-3.84) and FOLFIRI+Bmab (OR = 3.14, 95% CrI = 1.51-5.89). FOLFOX+Cmab and FOLFIRI+Bmab showed high probabilities of being first- and second-line treatments in terms of the efficacy and safety, respectively. The findings of the efficacy and safety comparisons may support the selection of appropriate treatments in clinical practice. PROSPERO registration: CRD42020153640.

Impact of Size and Location of Metastases on Early Tumor Shrinkage and Depth of Response in Patients With Metastatic Colorectal Cancer: Subgroup Findings of the Randomized, Open-Label Phase 3 Trial FIRE-3/AIO KRK-0306

BACKGROUND

The Response Evaluation Criteria in Solid Tumors (RECIST) are used to define degrees of response to chemotherapy. For accelerated response evaluation, early tumor shrinkage (ETS) of ≥ 20% has been suggested as a predictor for outcome in metastatic colorectal cancer (mCRC). Together with depth of response (DpR), new alternative metrics have been provided, yielding promising outcome parameters. In this analysis, we aimed to further characterize ETS and DpR.

PATIENTS AND METHODS

This analysis was based on FIRE-3, a randomized phase 3 trial comparing first-line FOLFIRI plus either cetuximab or bevacizumab in KRAS exon 2 wild-type mCRC. ETS and DpR were determined on the basis of RECIST 1.1 in a blinded radiologic review. ETS was evaluated as a categorized (≥ 20% shrinkage) and continuous parameter. The impact of baseline location and size of metastases on ETS and DpR were evaluated by univariate and multivariate analyses.

RESULTS

Of 592 patients, 395 (66.7%) had data available for radiologic review. Median continuous ETS for lung, liver, and suspected lymph node metastases was 20%, 23%, and 30%, respectively. The median DpR was -32%, -44%, and -50%, respectively (all P < .01). In multivariate analysis, lung metastases were significantly associated with inferior DpR (P = .021), whereas hepatic metastases led to higher DpR (P = .024). Large metastases were associated with favorable ETS, whereas small metastases were correlated with higher DpR (P < .001).

CONCLUSION

ETS and DpR depend on the location and size of metastases in mCRC. These associations may establish the basis for further research to optimize the predictive accuracy of both parameters. This may help basing treatment decisions on ETS and DpR.

Bayesian hierarchical meta-analytic methods for modeling surrogate relationships that vary across treatment classes using aggregate data

Surrogate endpoints play an important role in drug development when they can be used to measure treatment effect early compared to the final clinical outcome and to predict clinical benefit or harm. Such endpoints are assessed for their predictive value of clinical benefit by investigating the surrogate relationship between treatment effects on the surrogate and final outcomes using meta‐analytic methods. When surrogate relationships vary across treatment classes, such validation may fail due to limited data within each treatment class. In this paper, two alternative Bayesian meta‐analytic methods are introduced which allow for borrowing of information from other treatment classes when exploring the surrogacy in a particular class. The first approach extends a standard model for the evaluation of surrogate endpoints to a hierarchical meta‐analysis model assuming full exchangeability of surrogate relationships across all the treatment classes, thus facilitating borrowing of information across the classes. The second method is able to relax this assumption by allowing for partial exchangeability of surrogate relationships across treatment classes to avoid excessive borrowing of information from distinctly different classes. We carried out a simulation study to assess the proposed methods in nine data scenarios and compared them with subgroup analysis using the standard model within each treatment class. We also applied the methods to an illustrative example in colorectal cancer which led to obtaining the parameters describing the surrogate relationships with higher precision.

Magnitude of advantage in tumor response contributes to a better correlation between treatment effects on overall survival and progression-free survival: a literature-based meta-analysis of clinical trials in patients with metastatic colorectal cancer

BACKGROUND

Although it is suggested that the endpoints originated from the concept of tumor shrinkage dynamics, such as early tumor shrinkage and depth of response, are strongly associated with overall survival (OS) in patients with metastatic colorectal cancer (mCRC), they are yet to be validated as a single surrogate endpoint of OS by themselves. This study aimed to investigate the impact of advantage in tumor response on the correlation between treatment effects on progression-free survival (PFS) and OS in mCRC patients.

METHODS

Based on an electronic search, we identified randomized controlled trials of first-line therapy for mCRC. The impact of advantage in objective response rate (ORR) on the correlation between treatment effects on PFS and OS was evaluated based on Spearman correlation coefficients (r_s).

RESULTS

Forty-seven trials with a total of 24,018 patients were identified. The hazard ratio for PFS showed a relatively higher correlation with that for OS (r_s = 0.63) when the trials were limited to those that demonstrated a larger difference in ORR, compared to the case for trials that demonstrated a smaller difference (r_s = 0.32). This tendency was also observed in the subgroup analysis stratified by the types of treatment agents (targeted or non-targeted).

CONCLUSIONS

The magnitude of advantage in tumor response was suggested to contribute to a better prediction of OS benefit based on PFS in patients with mCRC. The accuracy of OS estimation in mCRC is expected to be improved by considering the degree of tumor shrinkage in conjunction with PFS.

Combining tumour response and progression free survival as surrogate endpoints for overall survival in advanced colorectal cancer

BACKGROUND

Progression free survival (PFS) and tumour response (TR) have been investigated as surrogate endpoints for overall survival (OS) in advanced colorectal cancer (aCRC), however their validity has been shown to be suboptimal. In recent years, meta-analytic methods allowing for use of multiple surrogate endpoints jointly have been proposed. Our aim was to assess if PFS and TR used jointly as surrogate endpoints to OS improve their predictive value.

METHODS

Data were obtained from a systematic review of randomised controlled trials investigating effectiveness of pharmacological therapies in aCRC, including systemic chemotherapies, anti-epidermal growth factor receptor therapies and anti-angiogenic agents. Multivariate meta-analysis was used to model the association patterns between treatment effects on the surrogate endpoints (TR, PFS) and the final outcome (OS).

RESULTS

Analysis of 33 trials reporting treatment effects on all three outcomes showed reasonably strong association between treatment effects on PFS and OS, however the association parameters were obtained with a large uncertainty. A weak surrogate relationship was noted between the treatment effects on TR and OS. Modelling the two surrogate endpoints, TR and PFS, jointly as predictors of treatment effect on OS gave no marked improvement to surrogate association patterns. Modest improvement in the precision of the predicted treatment effects on the final outcome was noted in studies investigating anti-angiogenic therapy, however it was likely due to chance.

CONCLUSION

The joint use of two surrogate endpoints did not lead to marked improvement in the association between treatment effects on surrogate and final endpoints in advanced colorectal cancer.

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.

Reconsideration of sample size and power calculation for overall survival in cancer clinical trials

When designing a cancer clinical trial, it is usual to assume an exponential distribution for a time-to-event outcome such as overall survival (OS). OS is often expressed as the sum of progression-free survival (PFS) and survival post-progression (SPP), each of which is assumed to be exponentially distributed. Then, OS does not follow an exponential distribution any more but a gamma or hypo-exponential distribution. In this study, we derived a sample size calculation formula for comparing OS between two treatment arms using the log-rank test for OS following a gamma or hypo-exponential distribution. We conducted a simulation study to evaluate the sample size and power calculation based on the gamma or hypo-exponential distribution. We found that we could reduce the sample sizes considerably compared to when assuming an exponential distribution for OS.

Cost-utility analysis of 5-fluorouracil and capecitabine for adjuvant treatment in locally advanced rectal cancer

Background

Adjuvant chemotherapy at concurrent time with radiation therapy (RT) or at adjuvant time alone in locally advanced rectal cancer (LARC) is used with several regimens. The cost-utility analysis was conducted to compare administration of two 5-FU regimens and capecitabine in the aspect of provider and societal viewpoint.

Methods

Stage II or III rectal cancer patients who received pre-operative or post-operative concurrent chemoradiotherapy and adjuvant chemotherapy were compared by using decision tree model between (I) 5-FU plus leucovorin (LV) for 5 days per cycle (Mayo Clinic regimen); (II) 5-FU continuous infusion (CI) for 120-h per cycle (CAO/ARO/AIO-94 protocol); (III) standard regimen of capecitabine. All probability data were extracted from landmark study. Direct medical costs were the cost from database of Drug Medical Supply Information Center, while direct non-medical cost and utility were interviewed from stage II and III rectal cancer patients. The time horizon of this study was 5 years. Incremental cost-effectiveness ratio (ICER) was the final result in this study, which determined as the numerator of the difference of costs among three drug regimens, and the difference of quality-adjusted life years (QALYs) from each drug was the denominator.

Results

5-FU plus LV was the cheapest and least efficacy for adjuvant treatment of LARC in both provider and societal viewpoint. In provider viewpoint, the ICERs of 5-FU CI and capecitabine were 334,550 THB/QALY (US $9,840/QALY) and 189,935 THB/QALY (US $5,586/QALY), respectively, with the corresponding societal viewpoint of 264,447 THB/QALY (US $7,778/QALY) and 119,120 THB/QALY (US $3,504/QALY) when 5-FU plus LV was used as comparator. The most influential parameter for value of treatment was acquisition cost of capecitabine. At the willingness to pay for one QALY gained in Thailand (160,000 THB or US $4,706), 5-FU plus LV, 5-FU CI and capecitabine had probabilities of cost-effectiveness of 63%, 2% and 35%, respectively.

Conclusions

Capecitabine was the most expensive regimen but produced the higher effectiveness than 5-FU plus LV and 5-FU CI. The most influential parameter in the model was acquisition cost of capecitabine.

SPECT and PET radiopharmaceuticals for molecular imaging of apoptosis: from bench to clinic

Owing to the central role of apoptosis in many human diseases and the wide-spread application of apoptosis-based therapeutics, molecular imaging of apoptosis in clinical practice is of great interest for clinicians, and holds great promises. Based on the well-defined biochemical changes for apoptosis, a rich assortment of probes and approaches have been developed for molecular imaging of apoptosis with various imaging modalities. Among these imaging techniques, nuclear imaging (including single photon emission computed tomography and positron emission tomography) remains the premier clinical method owing to their high specificity and sensitivity. Therefore, the corresponding radiopharmaceuticals have been a major focus, and some of them like ^99mTc-Annexin V, ¹⁸F-ML-10, ¹⁸F-CP18, and ¹⁸F-ICMT-11 are currently under clinical investigations in Phase I/II or Phase II/III clinical trials on a wide scope of diseases. In this review, we summarize these radiopharmaceuticals that have been widely used in clinical trials and elaborate them in terms of radiosynthesis, pharmacokinetics and dosimetry, and their applications in different clinical stages. We also explore the unique features required to qualify a desirable radiopharmaceutical for imaging apoptosis in clinical practice. Particularly, a perspective of the impact of these clinical efforts, namely, apoptosis imaging as predictive and prognostic markers, early-response indicators and surrogate endpoints, is also the highlight of this review.

Surrogate Endpoints in Second-Line Trials of Targeted Agents in Metastatic Colorectal Cancer: A Literature-Based Systematic Review and Meta-Analysis

PURPOSE

The purpose of this study was to evaluate progression-free survival (PFS) and objective response rate (ORR) as surrogate endpoints of overall survival (OS) in modern clinical trials investigating the efficacy of targeted agents in the second-line treatment of metastatic colorectal cancer (mCRC).

MATERIALS AND METHODS

A systematic search of literature pertaining to randomized phase II and III trials evaluating targeted agents as second-line treatments for mCRC was performed. The strength of the correlation between both PFS and ORR and OS was assessed based on the Pearson's correlation coefficient (R) and the coefficient of determination (R2).

RESULTS

Twenty trials, including a total of 7,571 patients, met the search criteria. The median duration of post-progression survival (PPS) was 7.6 months. The median differences between experimental and control arms were 0.65 months (range, -2.4 to 3.4) for the median PFS and 0.7 months (range, -5.8 to 3.9) for the median OS. PFS and ORR showed moderate (R=0.734, R2=0.539, p < 0.001) and poor correlation (R=0.169, R2=0.029, p=0.476) with OS, respectively. No differences between anti-angiogenic agents and other drugs were evident.

CONCLUSION

Targeted agents investigated in the second-line treatment of mCRC provided minimal PFS gains translating into modest OS improvements. Considering both the moderate correlation between PFS and OS and the short duration of PPS, the OS should remain the preferred primary endpoint for randomized clinical trials in the second-line treatment of mCRC.

Recurrence-free survival as a putative surrogate for overall survival in phase III trials of curative-intent treatment of colorectal liver metastases: Systematic review

AIM

To verify whether recurrence-free survival (RFS) surrogates overall survival (OS) in phase III trials for resectable colorectal liver metastases (CRLM).

METHODS

MEDLINE, EMBASE, and Scopus databases were consulted. Eligible studies were phase III trials testing any type of systemic therapy (neoadjuvant, adjuvant or perioperative) added to surgery in patients with resectable CRLM. A linear regression model based on hazard ratios (HR) of OS and RFS was performed.

RESULTS

Of 3059 studies, 5 phase III trials (1162 patients) were included for analyses. A linear regression weighted by each trial was used to estimate the association between each HR and RFS. The originated formula was: OS HR = (0.93 × RFS HR) + 0.14; with RFS 95%CI (0.48-1.38), with P = 0.007.

CONCLUSION

This association suggests that RFS could work as a putative surrogate endpoint of OS in this population, avoiding bigger, longer and more resource-consuming trials. The OS could be assumed based on RFS and our model could be useful to better estimate sample size calculations of phase III trials of CRLM aiming for OS.

A Review of Modeling Approaches to Predict Drug Response in Clinical Oncology

Model-based approaches have emerged as important tools for quantitatively understanding temporal relationships between drug dose, concentration, and effect over the course of treatment, and have now become central to optimal drug development and tailored drug treatment. In oncology, the therapeutic index of a chemotherapeutic drug is typically narrow and a full dose-response relationship is not available, often because of treatment failure. Noting the benefits of model-based approaches and the low therapeutic index of oncology drugs, in recent years, modeling approaches have been increasingly used to streamline oncologic drug development through early identification and quantification of dose-response relationships. With this background, this report reviews publications that used model-based approaches to evaluate drug treatment outcome variables in oncology therapeutics, ranging from tumor size dynamics to tumor/biomarker time courses and survival response.

Efficacy and safety of bevacizumab plus chemotherapy compared to chemotherapy alone in previously untreated advanced or metastatic colorectal cancer: a systematic review and meta-analysis

BACKGROUND

Colorectal cancer (CRC) is the fourth most frequently diagnosed cancer and the second leading cause of neoplasm-related death in the United States. Several studies analyzed the efficacy of bevacizumab combined with different chemotherapy regimens consisting on drugs such as 5-FU, capecitabine, irinotecan and oxaliplatin. This systematic review aims to evaluate the effectiveness and safety of chemotherapy plus bevacizumab versus chemotherapy alone in patients with previously untreated advanced or metastatic colorectal cancer (mCRC).

METHODS

Several databases were searched, including MEDLINE, EMBASE, LILACS, and CENTRAL. The primary endpoints were overall survival and progression-free survival. Data extracted from the studies were combined by using hazard ratio (HR) or risk ratio (RR) with their corresponding 95 % confidence intervals (95 % CI).

RESULTS

The final analysis included 9 trials comprising 3,914 patients. Patients who received the combined treatment (chemotherapy + bevacizumab) had higher response rates (RR = 0.89; 95 % CI: 0.82 to 0.96; p = 0.003) with heterogeneity, higher progression-free survival (HR = 0.69; 95 % CI: 0.63 to 0.75; p < 0.00001) and also higher overall survival rates (HR = 0.87; 95 % CI: 0.80 to 0.95; p = 0.002) with moderate heterogeneity. Regarding adverse events and severe toxicities (grade ≥ 3), the group receiving the combined therapy had higher rates of hypertension (RR = 3.56 95 % CI: 2.58 to 4.92; p < 0.00001), proteinuria (RR = 1.89; 95 % CI: 1.26 to 2.84; p = 0.002), gastrointestinal perforation (RR = 3.63; 95 % CI: 1.31 to 10.09; p = 0.01), any thromboembolic events (RR = 1.44; 95 % CI: 1.20 to 1.73; p = 0.0001), and bleeding (RR = 1.81; 95 % CI: 1.22 to 2.67; p = 0.003).

CONCLUSION

The combination of chemotherapy with bevacizumab increased the response rate, progression-free survival and overall survival of patients with mCRC without prior chemotherapy. The results of progression-free survival (PFS) and overall survival (OS) were comparatively higher in those subgroups of patients receiving bolus 5-FU or capecitabine-based chemotherapy plus bevacizumab, when compared to patients treated with infusional %-FU plus bevacizumab (no difference in PFS and OS). Regarding the type of cytotoxic scheme, regimens containing irinotecan and fluoropyrimidine monotherapy showed superior efficacy results when combined to bevacizumab.

Timing and extent of response in colorectal cancer: critical review of current data and implication for future trials

The identification of new surrogate endpoints for advanced colorectal cancer is becoming crucial and, along with drug development, it represents a research field increasingly studied. Although overall survival (OS) remains the strongest trial endpoint available, it requires larger sample size and longer periods of time for an event to happen. Surrogate endpoints such as progression free survival (PFS) or response rate (RR) may overcome these issues but, as such, they need to be prospectively validated before replacing the real endpoints; moreover, they often bear many other limitations. In this narrative review we initially discuss the role of time-to-event endpoints, objective response and response rate as surrogates of OS in the advanced colorectal cancer setting, discussing also how such measures are influenced by the tumor assessment criteria currently employed. We then report recent data published about early tumor shrinkage and deepness of response, which have recently emerged as novel potential endpoint surrogates, discussing their strengths and weaknesses and providing a critical comment. Despite being very compelling, the role of such novel response measures is yet to be confirmed and their surrogacy with OS still needs to be further investigated within larger and well-designed trials.

Patterns of progression, treatment of progressive disease and post-progression survival in the New EPOC study

BACKGROUND

The addition of cetuximab (CTX) to perioperative chemotherapy (CT) for operable colorectal liver metastases resulted in a shorter progression-free survival. Details of disease progression are described to further inform the primary study outcome.

METHODS

A total of 257 KRAS wild-type patients were randomised to CT alone or CT with CTX. Data regarding sites and treatment of progressive disease were obtained for the 109 (CT n=48, CT and CTX n=61) patients with progressive disease at the cut-off date for analysis of November 2012.

RESULTS

The liver was the most frequent site of progression (CT 67% (32/48); CT and CTX 66% (40/61)). A higher proportion of patients in the CT and group had multiple sites of progressive disease (CT 8%, 4/48; CT and CTX 23%, 14/61 P=0.04). Further treatment for progressive disease is known for 84 patients of whom 69 received further CT, most frequently irinotecan based. Twenty-two patients, 11 in each arm, received CTX as a further line agent.

CONCLUSIONS

Both the distribution of progressive disease and further treatment are as expected for such a cohort. The pattern of disease progression seen is consistent with failure of systemic micrometastatic disease control rather than failure of local disease control following liver surgery.

Understanding the FOLFOXIRI-regimen to optimize treatment for metastatic colorectal cancer

The management of metastatic colorectal cancer substantially improved over the last 10 years and median overall survival of patients might exceed 30 months. The selection of an effective first-line treatment represents a crucial point in order to achieve good outcome results. In the last years, the intensive FOLFOXIRI regimen in combination with bevacizumab became a new standard option in this setting. In the present review we summarized the main steps of FOLFOXIRI regimen development from the first pilot study to the recent findings with biological agents, with a specific focus on practical aspects, such as patient's selection, adverse event management, treatment schedules and post-progression strategies. Possible predictive markers, open issues and ongoing clinical trials have been also deeply described.

Verification of the correlation between progression-free survival and overall survival considering magnitudes of survival post- progression in the treatment of four types of cancer

BACKGROUND

With development and application of new and effective anti-cancer drugs, the median survival post-progression (SPP) is often prolonged, and the role of the median SPP on surrogacy performance should be considered. To evaluate the impact of the median SPP on the correlation between progression-free survival (PFS) and overall survival (OS), we performed simulations for treatment of four types of cancer, advanced gastric cancer (AGC), metastatic colorectal cancer (MCC), glioblastoma (GBM), and advanced non-small-cell lung cancer (ANSCLC).

MATERIALS AND METHODS

The effects of the median SPP on the statistical properties of OS and the correlation between PFS and OS were assessed. Further, comparisons were made between the surrogacy performance based on real data from meta-analyses and simulation results with similar scenarios.

RESULTS

The probability of a significant gain in OS and HR for OS was decreased by an increase of the SPP/ OS ratio or by a decrease of observed treatment benefit for PFS. Similarly, for each of the four types of cancer, the correlation between PFS and OS was reduced as the median SPP increased from 2 to 12 months. Except for ANSCLC, for which the median SPP was equal to the true value, the simulated correlation between PFS and OS was consistent with the values derived from meta-analyses for the other three kinds of cancer. Further, for these three types of cancer, when the median SPP was controlled at a designated level (i.e., < 4 months for AGC, < 12 months for MCC, and <6 months for GBM), the correlation between PFS and OS was strong; and the power of OS reached 34.9% at the minimum.

CONCLUSIONS

PFS is an acceptable surrogate endpoint for OS under the condition of controlling SPPs for AGC, MCC, and GBM at their limit levels; a similar conclusion cannot be made for ANSCLC.

Combined Analysis of EGFR and PTEN Status in Patients With KRAS Wild-Type Metastatic Colorectal Cancer

To determine the relationship between the expression of phosphatase and tensin homologue (PTEN) and epidermal growth factor receptor (EGFR) in metastatic colorectal cancer (mCRC) and the clinical outcome of cetuximab-containing chemotherapy. A total of 158 consecutive mCRC patients with wild-type KRAS status who received chemotherapy with or without cetuximab, and for whom tumor tissue was available, were enrolled. The EGFR and PTEN expression was determined by immunohistochemistry (IHC). A total of 158 mCRC patients with wild-type KRAS status were enrolled in the study; 51 patients received chemotherapy combined with cetuximab, 107 patients received chemotherapy alone. Patients who received chemotherapy combined with cetuximab had longer overall survival (OS) compared with patients who received chemotherapy alone. High EGFR expression was detected in 60 patients (38.0%), while normal PTEN expression was detected in 60 patients (59.5%). The PTEN status was significantly related with the histological grade. For patients who received chemotherapy combined with cetuximab the median OS of patients with high-expression of EGFR was longer than the OS of patients with low EGRF expression; 25.0 versus 19.0 months, P = 0.002. For patient with normal PTEN the median OS were longer than the median OS for patients with loss of PTEN; 24.0 versus 19.0 months, P = 0.026. The overall response rate (ORR) had a borderline association with EGFR and PTEN expression (P = 0.055 and 0.048, respectively). In a multivariate analysis, ECOG PS, EGFR status, chemotherapy ± cetuximab, and the interaction of EGFR or PTEN and chemotherapy ± cetuximab were independent prognostic factors for OS. Our findings show that chemotherapy combined with cetuximab demonstrated encouraging antitumor activity for mCRC patients with wild-type KRAS status. Especially, those who have high EGFR expression or normal PTEN expression were more likely to benefit from such a treatment strategy. Subsequent studies in clinical trial cohorts will be required to confirm the clinical utility of these markers.

'Deepness of Response' Is Associated with Overall Survival in Standard Systemic Chemotherapy for Metastatic Colorectal Cancer

BACKGROUND

The identification of responders is an important issue in chemotherapy for metastatic colorectal cancer (mCRC). 'Deepness of response' (DpR), defined as the maximum rate of reduction from the initial tumor burden, was recently proposed as a novel hypothetical parameter associated with overall survival (OS) in first-line chemotherapy plus cetuximab for mCRC. We determined whether this concept was universally applicable to diverse standard chemotherapeutic regimens for mCRC.

METHODS

We reviewed mCRC patients who received the first-line systemic chemotherapy regimens FOLFOX, CapeOX or FOLFIRI (with biologics) at our department between June 2005 and March 2015. Data such as clinicopathological parameters, metastasized organs, chemotherapeutic regimens, the best response by RECIST v1.1, progression-free survival (PFS) and OS were retrospectively retrieved for patients who exhibited tumor shrinkage. DpR was calculated as the uni-dimensional maximum reduction rate of measurable tumors. We addressed the association between DpR and survival.

RESULTS

Of the 156 patients receiving first-line chemotherapy regimens, tumor shrinkage was observed in 63 (41 of whom were men; median age 62 years). Complete remission was achieved in 6 patients, partial remission in 42 and stable disease in 15. The median DpR was 44.2% and was employed as the cutoff, in line with previous reports. DpR ≥45% (31 patients) was correlated with longer PFS (median 16.4 vs. 8.1 months for DpR <45%, p = 0.006) and OS (median 58.6 vs. 30.9 months for DpR <45%, p = 0.041). There was basically no difference in the subsequent chemotherapy between the DpR ≥45% and DpR <45% groups.

CONCLUSION

DpR correlated with OS in various first-line systemic upfront chemotherapy regimens for mCRC.

FOLFOXIRI plus bevacizumab versus FOLFIRI plus bevacizumab as first-line treatment of patients with metastatic colorectal cancer: updated overall survival and molecular subgroup analyses of the open-label, phase 3 TRIBE study

BACKGROUND

In the TRIBE study, FOLFOXIRI (fluorouracil, leucovorin, oxaliplatin, and irinotecan) plus bevacizumab significantly improved progression-free survival of patients with metastatic colorectal cancer compared with FOLFIRI (fluorouracil, leucovorin, and irinotecan) plus bevacizumab. In this updated analysis, we aimed to provide mature results for overall survival-a secondary endpoint-and report treatment efficacy in RAS and BRAF molecular subgroups.

METHODS

TRIBE was an open-label, multicentre, phase 3 randomised study of patients (aged 18-70 years with Eastern Cooperative Oncology Group [ECOG] performance status of 2 or less and aged 71-75 years with an ECOG performance status of 0) with unresectable metastatic colorectal cancer who were recruited from 34 Italian oncology units. Patients were randomly assigned (1:1) via a web-based procedure to receive FOLFIRI plus bevacizumab or FOLFOXIRI plus bevacizumab. Bevacizumab was given as a 5 mg/kg intravenous dose. FOLFIRI consisted of a 180 mg/m(2) intravenous infusion of irinotecan for 60 min followed by a 200 mg/m(2) intravenous infusion of leucovorin for 120 min, a 400 mg/m(2) intravenous bolus of fluorouracil, and a 2400 mg/m(2) continuous infusion of fluorouracil for 46 h. FOLFOXIRI consisted of a 165 mg/m(2) intravenous infusion of irinotecan for 60 min, followed by an 85 mg/m(2) intravenous infusion of oxaliplatin given concurrently with 200 mg/m(2) leucovorin for 120 min, followed by a 3200 mg/m(2) continuous infusion of fluorouracil for 48 h. Tissue samples for RAS and BRAF mutational status analyses were centrally collected. In this updated analysis, we assessed the secondary endpoint of overall survival in the main cohort and treatment efficacy in RAS and BRAF molecular subgroups. All analyses were by intention to treat. TRIBE was concluded on Nov 30, 2014. The trial is registered with ClinicalTrials.gov, number NCT00719797.

FINDINGS

Between July 17, 2008, and May 31, 2011, 508 patients were randomly assigned. At a median follow-up of 48·1 months (IQR 41·7-55·6), median overall survival was 29·8 months (95% CI 26·0-34·3) in the FOLFOXIRI plus bevacizumab group compared with 25·8 months (22·5-29·1) in the FOLFIRI plus bevacizumab group (hazard ratio [HR] 0·80, 95% CI 0·65-0·98; p=0·03). Median overall survival was 37·1 months (95% CI 29·7-42·7) in the RAS and BRAF wild-type subgroup compared with 25·6 months (22·4-28·6) in the RAS-mutation-positive subgroup (HR 1·49, 95% CI 1·11-1·99) and 13·4 months (8·2-24·1) in the BRAF-mutation-positive subgroup (HR 2·79, 95% CI 1·75-4·46; likelihood-ratio test p<0·0001). Treatment effect was not significantly different across molecular subgroups (pinteraction=0·52).

INTERPRETATION

FOLFOXIRI plus bevacizumab is a feasible treatment option for those patients who meet the inclusion criteria of the present study, irrespective of baseline clinical characteristics and RAS or BRAF mutational status.

Effectiveness of bevacizumab added to standard chemotherapy in metastatic colorectal cancer: final results for first-line treatment from the ITACa randomized clinical trial

BACKGROUND

We report the results from a first-line phase III randomized clinical trial on metastatic colorectal cancer (mCRC) aimed at evaluating the effectiveness of adding bevacizumab (B) to standard first-line chemotherapy (CT).

PATIENTS AND METHODS

mCRC patients were randomized to receive first-line CT (FOLFIRI or FOLFOX4) plus B (arm A) or CT only (arm B). The primary end point was progression-free survival (PFS). Secondary end points included overall survival (OS), response rate (ORR) and safety. Three hundred and fifty patients and 310 events were required to have an 80% statistical power to detect a difference in PFS between the groups.

RESULTS

Between November 2007 and March 2012, 376 patients were randomized. About 60% of patients received FOLFOX4 and 40% FOLFIRI. After a median follow-up of 36 months, 343 progressions and 275 deaths had been observed in the overall population. The median PFS was 9.6 [95% confidence interval (CI) 8.2-10.3] and 8.4 (95% CI 7.2-9.0) months for arms A and B, respectively, with a hazard ratio of 0.86 (95% CI 0.70-1.07; P = 0.182). No statistically significant differences in OS or ORR were observed. B-containing regimens were associated with more frequent hypertension, bleeding, proteinuria and asthenia.

CONCLUSIONS

The addition of B to standard first-line CT for mCRC did not provide a benefit in terms of PFS, OS or ORR. Further research is warranted to better identify the target population.

CLINICAL TRIAL NUMBER

NCT01878422.

Detecting overall survival benefit derived from survival postprogression rather than progression-free survival

Broglio and Berry (2009) examined the impact of survival postprogression (SPP) on overall survival (OS) when progression-free survival (PFS) was used to assess treatment effect in metastatic cancer. Their simulation studies found no statistical difference in OS because of dilution effect from SPP, although there was a statistical difference in PFS between treatment arms. Recently, two phase III clinical trials showed efficacy of experimental treatments in OS, but not PFS. These results seem counterintuitive, because it may be reasonable to consider that the effect of treatment in prolonging PFS can influence OS prolongation. We conducted simulations to examine the role of SPP in OS under the assumption that only SPP, and not PFS, differed between treatment arms. We also explored the impact of patient heterogeneity on the OS analysis. Our study offers a reasonable explanation for the two phase III trials and recommends further discussion of PFS as an adequate endpoint and what role SPP might play in OS to evaluate current treatment regimens.

Guidelines for diagnosis, staging and treatment of metastatic colorectal cancer by Grupo Español Multidisciplinar en Cancer Digestivo (GEMCAD)

Abstract 

Advances in the care of patients with metastatic colorectal cancer arise from well-designed clinical trials. In the present document we address specific challenges in the design of clinical trials for metastatic colorectal cancer regarding staging and standard of care according to prognosis, as well as some relevant methodological issues.

Progression-free survival as surrogate endpoint in advanced pancreatic cancer: meta-analysis of 30 randomized first-line trials

BACKGROUND

Progression-free survival (PFS) has not been extensively investigated as a surrogate for survival in the first-line treatments of pancreatic cancer. The aim of this review was to evaluate PFS as a potential surrogate endpoint for overall survival (OS) in advanced pancreatic cancer in trials comparing poly-chemotherapy to gemcitabine alone.

DATA SOURCES

A systematic literature search in PubMed, Embase, Web of Science, and the Cochrane Central Register of Controlled Trials was conducted. The key words included randomized trial, first-line chemotherapy, pancreatic cancer, gemcitabine and poly-chemotherapy. Adjusted weighted linear regression was used to calculate RS (Spearman's rank-order correlation coefficient) between PFS and post-progression survival (PPS) with OS (RS) and between treatment effects on PFS and OS (RHR).

RESULTS

A total of 30 trials including 8467 patients met the inclusion criteria. Correlation between the treatment effects on PFS and OS (RHR=0.78) and between the endpoint PFS and OS was high across all studies (RS=0.75). The slope of the regression line was 0.76+/-0.26, indicating that an agent producing a 10% risk reduction for PFS will provide a 7.6%+/-2.6% risk reduction for OS. Correlation between PPS and OS was very strong (RS=0.71) and accounted for more than 50% of the whole OS variability (R2=0.57).

CONCLUSION

Because of the robust correlation with OS and the potential influence of PPS caused by the second line therapies, it may be justified to consider PFS as a surrogate endpoint in trials evaluating new cytotoxic agents when gemcitabine is the control arm.

Surrogate endpoints in second-line treatment for mCRC: a systematic literature-based analysis from 23 randomised trials

PURPOSE

To evaluate progression-free survival (PFS), overall response rate (ORR) and disease control rate (DCR) as potential surrogate endpoints (SEP) for overall survival (OS) in second-line treatment for metastatic colorectal cancer (mCRC).

METHODS

A systematic literature search of randomised trials of second-line chemotherapy for mCRC reported from January 2000 to July 2013 was performed. Correlation coefficients weighted by number of patients in the treatment arms between median PFS, ORR and DCR with median OS were estimated.

RESULTS

Twenty-three trials reflecting 10 800 patients met the inclusion criteria. Median PFS and OS across all trials were 4.5 months and 11.5 months and median ORR and DCR were 11.4% and 65%, respectively. PFS showed moderate correlation with OS [RPFS = 0.73; 95% confidence interval (CI) 0.61-0.82]. In contrast, ORR only weakly correlated with OS (RORR = 0.58; 95% CI 0.38-0.72, n = 22). Despite a small number of studies (n = 10) reporting on DCR, moderate correlation with OS was observed (RDCR = 0.74; 95% CI 0.56-0.86).

CONCLUSION

Based on the available trial-level data, PFS may serve as an appropriate SEP in second-line chemotherapy for mCRC. A small number of studies revealed moderate correlation of DCR with OS that justifies further investigation.

Acceptance of surrogate end points in clinical trials supporting approval of drugs for cancer treatment by the Japanese regulatory agency

BACKGROUND

This study investigated the historic use of different end points to support approval of drugs for cancer treatment in Japan.

PATIENTS AND METHODS

Anticancer drugs approved between April 2001 and April 2014 were comprehensively investigated using publicly available information.

RESULTS

Before the revision of the guideline for oncology drugs in April 2006 in Japan, >80% of end points supporting approval were response rate and overall survival (OS) was not frequent. After the revision of the guideline in Japan, using OS in pivotal clinical trials applied for approval increased to more than approximately one-third of oncology drugs, although trials with an end point of response rate decreased. Regarding drugs for major cancers including non-small-cell lung cancer, gastric cancer, colorectal cancer, and breast cancer, survival was used as an end point in 44.0%, whereas surrogate end points were used in 56.0%. Exploration of potential factors for using surrogate end points other than survival carried out through determinations of odds ratios and 95% confidence intervals identified 'orphan drug designation in Japan' and 'accelerated approval by the U.S. Food and Drug Administration' as significant factors.

CONCLUSIONS

The revised guideline for oncology drugs in Japan requires the results of phase 3 studies with survival as an end point at the time of new drug application at least for major cancers. The regulatory agency in Japan also accepts surrogate end points as end points supporting approval besides survival; however, the number of surrogate end points has decreased after the revision of the guideline. We consider that accepting surrogate end points in the Japanese regulatory systems is important to approve oncology drugs quickly in Japan.

Optimizing oncology therapeutics through quantitative translational and clinical pharmacology: challenges and opportunities

Despite advances in biomedical research that have deepened our understanding of cancer hallmarks, resulting in the discovery and development of targeted therapies, the success rates of oncology drug development remain low. Opportunities remain for objective dose selection informed by exposure-response understanding to optimize the benefit-risk balance of novel therapies for cancer patients. This review article discusses the principles and applications of modeling and simulation approaches across the lifecycle of development of oncology therapeutics. Illustrative examples are used to convey the value gained from integration of quantitative clinical pharmacology strategies from the preclinical-translational phase through confirmatory clinical evaluation of efficacy and safety.

Therapeutic evaluation criteria for advanced colorectal cancer: Recent progress

Evaluation criteria like overall survival (OS), progression-free survival (PFS), the response evaluation criteria in solid tumors, quality of life and adverse reactions have been widely used in clinical studies of advanced colorectal cancer. However, these criteria have different significance, and with the development of molecular targeted drugs and new therapies, the drawbacks of these criteria have been revealed. Therefore, searching for new evaluation criteria which can reflect the curative effect in the earlier stage is becoming inevitable.