The impact of high PD-L1 expression on the surrogate endpoints and clinical outcomes of anti-PD-1/PD-L1 antibodies in non-small cell lung cancer

Predict progression free survival and overall survival using objective response rate for anti-PD1/PDL1 therapy development

In oncology anti-PD1 / PDL1 therapy development for solid tumors, objective response rate (ORR) is commonly used clinical endpoint for early phase study decision making, while progression free survival (PFS) and overall survival (OS) are widely used for late phase study decision making. Developing predictive models to late phase outcomes such as median PFS (mPFS) and median OS (mOS) based on early phase clinical outcome ORR could inform late phase study design optimization and probability of success (POS) evaluation. In existing literature, there are ORR / mPFS / mOS association and surrogacy investigations with limited number of included clinical trials. In this paper, without establishing surrogacy, we attempt to predict late phase survival (mPFS and mOS) based on early efficacy ORR and optimize late phase trial design for anti-PD1 / PDL1 therapy development. In order to include adequate number of eligible clinical trials, we built a comprehensive quantitative clinical trial landscape database (QLD) by combining information from different sources such as clinicaltrial.gov, publications, company press releases for relevant indications and therapies. We developed a generalizable algorithm to systematically extract structured data for scientific accuracy and completeness. Finally, more than 150 late phase clinical trials were identified for ORR / mPFS (ORR / mOS) predictive model development while existing literature included at most 50 trials. A tree-based machine learning regression model has been derived to account for ORR / mPFS (ORR / mOS) relationship heterogeneity across tumor type, stage, line of therapy, treatment class and borrow strength simultaneously when homogeneity persists. The proposed method ensures that the predictive model is robust and have explicit structure for clinical interpretation. Through cross validation, the average predictive mean square error of the proposed model is competitive to random forest and extreme gradient boosting methods and outperforms commonly used additive or interaction linear regression models. An example application of the proposed ORR / mPFS (ORR / mOS) predictive model on late phase trial POS evaluation for anti-PD1 / PDL1 combination therapy was illustrated.

Correlations between objective response rate and survival-based endpoints in first-line advanced non-small cell lung Cancer: A systematic review and meta-analysis

INTRODUCTION

The study objective was to estimate the relationship between objective response and survival-based endpoints by drug class, in first-line advanced non-small cell lung cancer (aNSCLC).

MATERIALS AND METHODS

A systematic literature review identified randomized controlled trials (RCTs) of first-line aNSCLC therapies reporting overall survival (OS), progression-free survival (PFS), and/or objective response rate (ORR). Trial-level and arm-level linear regression models were fit, accounting for inclusion of immunotherapy (IO)-based or chemotherapy-only RCT arms. Weighted least squares-based R² were calculated along with 95% confidence intervals (CIs). For the main trial-level analysis of OS vs. ORR, the surrogate threshold effect was estimated. Exploratory analyses involved further stratification by: IO monotherapy vs. chemotherapy, dual-IO therapy vs. chemotherapy, and IO + chemotherapy vs. chemotherapy.

RESULTS

From 17,040 records, 57 RCTs were included. In the main analysis, trial-level associations between OS and ORR were statistically significant in both the IO-based and chemotherapy-only strata, with R² estimates of 0.54 (95% CI: 0.26-0.81) and 0.34 (0.05-0.63), respectively. OS gains associated with a given ORR benefit were statistically significantly larger within IO vs. chemotherapy comparisons compared to chemotherapy vs. chemotherapy comparisons (p < 0.001). Exploratory analysis suggested a trend by IO type: for a given change in ORR, 'pure' IO (IO monotherapy and dual-IO) vs. chemotherapy RCTs tended to have a larger OS benefit than IO + chemotherapy vs. chemotherapy RCTs. For ORR vs. PFS, trial-level correlations were strong in the IO-based vs. chemotherapy (R² = 0.84; 0.72-0.95), and chemotherapy vs. chemotherapy strata (R² = 0.69; 0.49-0.88). For OS vs. PFS, correlations were moderate in both strata (R² = 0.49; 0.20-0.78 and R² = 0.49; 0.23-0.76).

CONCLUSION

The larger OS benefit per unit of ORR benefit in IO-based RCTs compared to chemotherapy-only RCTs provides an important addition to the established knowledge regarding the durability and depth of response in IO-based treatments.

Modelling approaches for histology-independent cancer drugs to inform NICE appraisals: a systematic review and decision-framework

BACKGROUND

The first histology-independent marketing authorisation in Europe was granted in 2019. This was the first time that a cancer treatment was approved based on a common biomarker rather than the location in the body at which the tumour originated. This research aims to explore the implications for National Institute for Health and Care Excellence appraisals.

METHODS

Targeted reviews were undertaken to determine the type of evidence that is likely to be available at the point of marketing authorisation and the analyses required to support National Institute for Health and Care Excellence appraisals. Several challenges were identified concerning the design and conduct of trials for histology-independent products, the greater levels of heterogeneity within the licensed population and the use of surrogate end points. We identified approaches to address these challenges by reviewing key statistical literature that focuses on the design and analysis of histology-independent trials and by undertaking a systematic review to evaluate the use of response end points as surrogate outcomes for survival end points. We developed a decision framework to help to inform approval and research policies for histology-independent products. The framework explored the uncertainties and risks associated with different approval policies, including the role of further data collection, pricing schemes and stratified decision-making.

RESULTS

We found that the potential for heterogeneity in treatment effects, across tumour types or other characteristics, is likely to be a central issue for National Institute for Health and Care Excellence appraisals. Bayesian hierarchical methods may serve as a useful vehicle to assess the level of heterogeneity across tumours and to estimate the pooled treatment effects for each tumour, which can inform whether or not the assumption of homogeneity is reasonable. Our review suggests that response end points may not be reliable surrogates for survival end points. However, a surrogate-based modelling approach, which captures all relevant uncertainty, may be preferable to the use of immature survival data. Several additional sources of heterogeneity were identified as presenting potential challenges to National Institute for Health and Care Excellence appraisal, including the cost of testing, baseline risk, quality of life and routine management costs. We concluded that a range of alternative approaches will be required to address different sources of heterogeneity to support National Institute for Health and Care Excellence appraisals. An exemplar case study was developed to illustrate the nature of the assessments that may be required.

CONCLUSIONS

Adequately designed and analysed basket studies that assess the homogeneity of outcomes and allow borrowing of information across baskets, where appropriate, are recommended. Where there is evidence of heterogeneity in treatment effects and estimates of cost-effectiveness, consideration should be given to optimised recommendations. Routine presentation of the scale of the consequences of heterogeneity and decision uncertainty may provide an important additional approach to the assessments specified in the current National Institute for Health and Care Excellence methods guide.

FURTHER RESEARCH

Further exploration of Bayesian hierarchical methods could help to inform decision-makers on whether or not there is sufficient evidence of homogeneity to support pooled analyses. Further research is also required to determine the appropriate basis for apportioning genomic testing costs where there are multiple targets and to address the challenges of uncontrolled Phase II studies, including the role and use of surrogate end points.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Evidence Synthesis programme and will be published in full in Health Technology Assessment; Vol. 25, No. 76. See the NIHR Journals Library website for further project information.

Exploring microsatellite instability in patients with advanced hepatocellular carcinoma and its tumor microenvironment

Background and Aim

Immune checkpoint inhibitors and their combination with other agents have recently been available in advanced hepatocellular carcinoma (HCC). Hence, a thorough understanding of the tumor microenvironment based on tumor samples is yet to be achieved. This study aimed to explore the tumor microenvironment in advanced HCC in terms of microsatellite instability‐high (MSI‐H) by using tumor samples from advanced HCC patients eligible for systemic therapy.

Methods

MSI‐H was assessed by polymerase chain reaction, and the expression of mismatch repair proteins, PD‐L1, CD8, VEGF, and HLA‐class1 was evaluated by immunohistochemistry. Whole‐exome sequencing was performed for MSI‐H tumor samples.

Results

Of 50 patients, one (2.0%) was confirmed with MSI‐H. In the MSI‐H advanced HCC tumor, a high tumor mutation burden, infiltration of CD8⁺ lymphocytes, and low expression of VEGF were identified. Although PD‐L1 expression was negative, there was shrinkage of tumor following pembrolizumab. However, another tumor nonresponsive to pembrolizumab was present simultaneously. Checking the Cancer Genome Atlas (TCGA) database, we found a similar case to this patient. The TCGA case had unique gene features of miR‐21 and miR‐155 overexpression and hypermethylation of the MSH2 gene.

Conclusion

We identified a very small number of MSI‐H cases in HCC using one tumor biopsy sample for each patient with advanced HCC. In addition, epigenetic aberrations possibly lead to MSI‐H in HCC patients. Since different HCC clones might coexist in the liver, sampling from multiple tumors should be considered to clarify the true proportion of MSI‐H in HCC and to analyze tumor microenvironments.

The progress and challenge of anti-PD-1/PD-L1 immunotherapy in treating non-small cell lung cancer

The use of programmed cell-death protein 1 (PD-1)/programmed cell-death ligand 1 (PD-L1) inhibitors is the standard therapy for the first-line or second-line treatment of patients with non-small-cell lung cancer (NSCLC). In contrast to current traditional treatments such as chemotherapy or radiotherapy, anti-PD-1 and anti-PD-L1 treatments can directly attenuate tumour-mediated exhaustion and effectively modulate the host anti-tumour immune response in vivo. In addition, compared with traditional therapy, PD-1/PD-L1 inhibitor monotherapy can significantly prolong survival without obvious side effects in the treatment of advanced NSCLC. Ideally, several biomarkers could be used to monitor the safety and effectiveness of anti-PD-1 and anti-PD-L1 treatments; however, the current lack of optimal prognostic markers remains a widespread limitation and challenge for further clinical applications, as does the possibility of immune-related adverse events and drug resistance. In this review, we aimed to summarise the latest progress in anti-PD-1/anti-PD-L1 treatment of advanced NSCLC, worldwide, including in China. An exploration of underlying biomarker identification and future challenges will be discussed in this article to facilitate translational studies in cancer immunotherapy.

Impact of Advantage in Tumor Response on the Correlation Between Progression-Free Survival and Overall Survival: Meta-Analysis of Clinical Trials in Patients with Advanced Non-Small Cell Lung Cancer

BACKGROUND

Progression-free survival (PFS) has not been validated as a surrogate endpoint for overall survival (OS) in patients with advanced non-small cell lung cancer.

OBJECTIVE

This study aimed to investigate an impact of advantage in tumor response on the correlation between PFS and OS in advanced non-small cell lung cancer.

METHODS

Based on a literature search, we identified randomized controlled trials of first-line therapy for advanced non-small cell lung cancer. The impact of absolute difference in objective response rate between treatment arms on the correlation between hazard ratios (HRs) for PFS and OS was evaluated based on Spearman rank correlation coefficients.

RESULTS

Sixty trials with a total of 29,134 patients were identified. The HR for PFS showed a relatively higher correlation with HR for OS (r_s = 0.75) when the trials were limited to those that demonstrated a larger advantage in objective response rate, compared with the case for trials that demonstrated a smaller advantage (r_s = 0.66). This tendency was also observed in the subgroup analysis stratified by the types of treatment agents (non-targeted, anti-angiogenic, and immunotherapy) except for the group of epidermal growth factor receptor-targeted agents.

CONCLUSIONS

The magnitude of advantage in tumor response was suggested to contribute to a better prediction of OS-HR based on PFS-HR in clinical trials in patients with advanced non-small cell lung cancer.

Clinical Efficacy of Immune Checkpoint Inhibitors in Older Non-small-Cell Lung Cancer Patients: A Meta-Analysis

Background: Immune checkpoint inhibitors (ICIs) have transformed the treatment landscape among non-small-cell lung cancer (NSCLC) patients. The efficacy of ICI therapy in older patients (≥65 years) is controversial and not fully clarified. We performed a systematic review and meta-analysis to evaluate the efficacy of ICIs in patients with advanced or metastatic NSCLC based on age (<65 years vs. ≥65 years). Methods: A comprehensive literature search for eligible randomized control phase II/III trials that compared the efficacy of anti-PD-1/PD-L1 agents against chemotherapy in advanced or metastatic NSCLC patients. Pooled overall survival (OS) and progression-free survival (PFS) estimates were calculated based on random/fixed effects models according to the heterogeneity between the studies. Results: A total of 10 studies involving 8 randomized controlled trials (2 updates) were enrolled in this meta-analysis [2,662 young patients (<65 years) and 1,971 older patients (≥65 years)]. The efficacy of anti-PD-1/PD-L1 agents is comparable between young (<65 years) and older (≥65 years) patients for OS [HR 0.75 95% CI (0.64-0.88) vs. 0.76 95% CI (0.66-0.87)]. However, our pooled analysis was not sufficient to show a significant benefit in terms of PFS for anti-PD-1/PD-L1 agents [HR 0.87 95% CI (0.74-1.01), P = 0.06]. In addition, we failed to see a PFS superiority of anti-PD-1/PD-L1 agents against chemotherapy in two age subgroups [<65 years and ≥65 years, HR 0.85 95% CI (0.72-1.01), P = 0.07 and HR 0.87 95% CI (0.68-1.10), P = 0.25]. Conclusion: ICIs therapy presents comparable efficacy in older advanced or metastatic NSCLC patients with young patients.

A systematic review of meta-analyses assessing the validity of tumour response endpoints as surrogates for progression-free or overall survival in cancer

BACKGROUND

Tumour response endpoints, such as overall response rate (ORR) and complete response (CR), are increasingly used in cancer trials. However, the validity of response-based surrogates is unclear. This systematic review summarises meta-analyses assessing the association between response-based outcomes and overall survival (OS), progression-free survival (PFS) or time-to-progression (TTP).

METHODS

Five databases were searched to March 2019. Meta-analyses reporting correlation or regression between response-based outcomes and OS, PFS or TTP were summarised.

RESULTS

The systematic review included 63 studies across 20 cancer types, most commonly non-small cell lung cancer (NSCLC), colorectal cancer (CRC) and breast cancer. The strength of association between ORR or CR and either PFS or OS varied widely between and within studies, with no clear pattern by cancer type. The association between ORR and OS appeared weaker and more variable than that between ORR and PFS, both for associations between absolute endpoints and associations between treatment effects.

CONCLUSIONS

This systematic review suggests that response-based endpoints, such as ORR and CR, may not be reliable surrogates for PFS or OS. Where it is necessary to use tumour response to predict treatment effects on survival outcomes, it is important to fully reflect all statistical uncertainty in the surrogate relationship.

Model-based simulation to support the extended dosing regimens of atezolizumab

PURPOSE

The currently recommended dosages of atezolizumab for patients with non-small cell lung cancer (NSCLC) and urothelial carcinoma (UC) is 840 mg every 2 weeks, 1200 mg every 3 weeks (q3w), and 1680 mg every 4 weeks (q4w). However, it has been argued that these dosages may not be optimal. This study aimed to explore the feasibility of extended dosing regimens by population pharmacokinetics (PK) simulations and exposure-response (E-R) relationships.

METHODS

All simulations were conducted based on the established population PK and E-R model for safety (i.e., adverse events of special interest, AESI) and efficacy (i.e., objective response rate, ORR) for patients with NSCLC or UC. The PK, AESI, and ORR profiles of the following dosing regimens were simulated: (i) 840 mg q4w, (ii) 1200 mg every 6 weeks (q6w), and (iii) 1680 mg q8w. These regimens were compared with those of the 1200 mg q3w standard regimen.

RESULTS

The simulation revealed that the ranking of efficacy for different extended dosing regimens were 1680 mg q8w ≅ 1200 mg q3w ≅ 1200 mg q6w > 840 mg q4w based on the predicted probability of ORR in patients with NSCLC and UC, and this ranking order was similar to that of the safety outcome of the AESI. The minimum serum concentration at steady-state (C_min,ss) values for all dosing regimens was all higher than the target effective concentration of 6 μg/mL.

CONCLUSION

The findings from this simulation suggest that extended dosing regimens are unlikely to significantly impair clinical outcomes and may provide more therapeutic benefits to patients in terms of safety.

Endpoint surrogacy in oncological randomized controlled trials with immunotherapies: a systematic review of trial-level and arm-level meta-analyses

Few cancer drugs or their indications achieved survival benefit in subsequent trials during postmarket period after approval based on surrogate endpoints. This causes a concern of using surrogate endpoints instead of overall survival (OS) as the primary endpoint for trial design, implementation and regulation approval. We conducted a systematic review to summarize the findings from published meta-analyses which have evaluated endpoint surrogacy for OS in oncological randomized controlled trials (RCTs) with immunotherapies. After searching articles indexed in PubMed prior to 24 February 2019, we identified a total of 11 meta-analyses for advanced multiple tumors, non-small cell lung cancer (NSCLC), urothelial carcinoma, renal cell carcinoma, melanoma; most (91%; 10/11) focused on immune checkpoint inhibitors. Although the evaluation criteria adopted by these meta-analyses for validating endpoint surrogacy were not consistent (ranging from R² ≥0.60 to R² ≥0.80), the results were consistent. Few studies show an association between OS and progression-free survival (PFS)/objective response rate (ORR) that met the lowest evaluation criteria (R² ≥0.60), based on treatment effects (8%; 2/26 indications) or absolute results from experimental arm (0%; 0/11 indications). However, the association between OS and 1-year survival rate met the lowest criteria based on both the trial-level results (4/4 indications) and the arm-level results (5/5 indications). In lieu of this finding, we are supportive of an alternative endpoint, e.g., 1-year survival rate, rather than the more conventional choices PFS and ORR, as promising surrogate endpoint for OS in immunotherapy RCTs. We encourage further investigation on endpoint surrogacy based on the same or different settings, especially an assessment on survival rate at milestone time (e.g., 1-year), which has been demonstrated valuable for predicting OS in meta-analyses.