Considerable interlaboratory variation in PD-L1 positivity in a nationwide cohort of non-small cell lung cancer patients

Why PD-L1 expression varies between studies of lung cancer: results from a Bayesian meta-analysis

PD-L1 expression is an important biomarker for the management of non-small cell lung cancer (NSCLC) but has been highly heterogeneous across studies. We developed a statistical model to reconcile conflicting estimates of PD-L1 prevalence by accounting for between-study variation in test sensitivity, specimen age, and laboratory count. In doing so, we obtained refined estimates for PD-L1 expression prevalence and identified differences by histological subtype, mutational status, and stage. Across 92 studies published between 2015 and 2023, the detectability of PD-L1 declined with increasing specimen age while the consistency of detection rates was greater for studies incorporating data from a higher number of laboratories. Using the 22C3 antibody as a benchmark, we predicted that 58.3% (95% CrI 49.8-66.1%) and 27.0% (95% CrI 21.2-33.1%) of NSCLC will have PD-L1 tumour proportion scores at the ≥ 1% and ≥ 50% threshold. PD-L1 expression was lower in EGFR-mutated NSCLC and higher in NSCLC with ALK, KRAS, MET, ROS1, and RET alterations. PD-L1 expression was more common with later-stage disease. Overall, this work highlights the continuing challenge of consistency in PD-L1 testing. Although the underlying prevalence of PD-L1 expression varies in the lung cancer population based on tumour-related factors, controllable differences in testing parameters also account for variations in PD-L1 prevalence.

Association Between PD-L1 Score and the Outcomes of Consolidation Durvalumab in a Large Nationwide Series of Patients With Stage III NSCLC Treated With Chemoradiotherapy

BACKGROUND

The Pacific trial reported improved outcomes when durvalumab was administered following concurrent chemoradiotherapy (CRT) for stage III NSCLC. Post-hoc subgroup analysis did not show favorable results for PD-L1 negative cases. We compared nationwide survival data with the trial outcomes, and evaluated the influence of PD-L1.

PATIENTS AND METHODS

Data from the Netherlands Cancer Registry were queried regarding patients with clinical stage III who underwent CRT, either by concurrent or sequential administration. Predictors for the use of consolidation treatment with durvalumab were evaluated by tabulations and logistic regression analysis. Overall survival (OS) was calculated from start of radiation or start of durvalumab and was stratified by PD-L1 score.

RESULTS

Between 2017 and 2021, application of consolidation durvalumab increased from 2% to 21%, 40%, 57%, 62%, respectively. In the period 2020-2021, durvalumab use was more frequent among patients with younger age, concurrent CRT, better performance score and proton radiation, but was irrespective of PD-L1 score. For patients receiving durvalumab (n = 1639), the 4-year OS was 53% overall (95%CI 50-57), and it was 56% (95%CI 52-60) after concurrent CRT. Four-year OS was considerably better for the PD-L1 subgroup ≧50% at 67% (95%CI 59-73), and it was similar for PD-L1 subgroups 0 and 1-49, at 51% (95%CI 42-58) and 46% (95%CI 39-54), respectively.

CONCLUSION

In real-world clinical practice, survival outcomes were equivalent to results from trial series. Overall survival in patients with negative PD-L1 was similar to the survival in patients with PD-L1 1-49, questioning the restrictions imposed by the European Medicines Agency.

Temporal Effect on PD-L1 Detection and Novel Insights Into Its Clinical Implications in Non-Small Cell Lung Cancer

OBJECTIVES

Several studies rely on archived tissue blocks to assess the PD-L1 scores; however, a detailed analysis of potential variations of scores between fresh and archived tissue blocks still lacks. In addition, the prognostic implications of PD-L1 in lung cancers have not yet been completely understood. Here, we aimed to investigate the temporal variation in PD-L1 scores from clinical samples and the clinical implications of PD-L1 in non-small cell lung cancer (NSCLC).

METHODS

NSCLC cases from January 2005 to June 2023 were considered for this study, and PD-L1 scores in archived and fresh tissue blocks were analyzed. Association of PD-L1 with various driver mutations was explored, and implications of PD-L1 in progression-free survival (PFS) and overall survival (OS) were analyzed.

RESULTS

Our study revealed a significant disparity in PD-L1 scores between archived and fresh tissue blocks, and a temporal variation in scores within 6 months of tissue acquisition. Advanced-stage primary tumors, metastatic lymph nodes, and visceral pleural invasion revealed higher PD-L1 expression as presented by tumor proportion score (TPS). Notably, in fully resected stage I/II NSCLC cases, OS was better in the high PD-L1 (≥ 50% TPS) cohort with driver mutations compared to cases without driver mutations (hazard ratio-0.5129, 95% confidence interval 0.2058-1.084, p = 0.0779). In contrast, high PD-L1 was associated with worse OS compared to no PD-L1 (< 1% TPS) (hazard ratio-2.431, 95% confidence interval 1.144-6.656, p = 0.0242) in the cohort without driver mutations. Furthermore, the presence of a KRAS mutation favored the outcome of anti-PD-L1/PD1 immunotherapy in advanced NSCLC.

CONCLUSION

PD-L1 detection from tissue blocks was found to vary temporally, urging for a prioritized consideration for patients with marginal scores when archived blocks are employed for its detection. Prognostic roles of PD-L1 were associated with driver mutations, and KRAS mutations favored the outcome of anti-PD-L1/PD1 therapy in advanced NSCLC.

Nationwide differences in cytology fixation and processing methods and their impact on interlaboratory variation in PD-L1 positivity

Programmed death ligand-1 (PD-L1) immunostaining, which aids clinicians in decision-making on immunotherapy for non-small cell lung cancer (NSCLC) patients, is sometimes performed on cytological specimens. In this study, differences in cytology fixation and cell block (CB) processing between pathology laboratories were assessed, and the influence of these differences on interlaboratory variation in PD-L1 positivity was investigated. Questionnaires on cytology processing were sent to all Dutch laboratories. Information gathered from the responses was added to data on all Dutch NSCLC patients with a mention of PD-L1 testing in their cytopathology report from July 2017 to December 2018, retrieved from PALGA (the nationwide network and registry of histo- and cytopathology in the Netherlands). Case mix-adjusted PD-L1 positivity rates were determined for laboratories with known fixation and CB method. The influence of differences in cytology processing on interlaboratory variation in PD-L1 positivity was assessed by comparing positivity rates adjusted for differences in the variables fixative and CB method with positivity rates not adjusted for differences in these variables. Twenty-eight laboratories responded to the survey and reported 19 different combinations of fixation and CB method. Interlaboratory variation in PD-L1 positivity was assessed in 19 laboratories. Correcting for differences in the fixative and CB method resulted in a reduction (from eight (42.1%) to five (26.3%)) in the number of laboratories that differed significantly from the mean in PD-L1 positivity. Substantial variation in cytology fixation and CB processing methods was observed between Dutch pathology laboratories, which partially explains the existing considerable interlaboratory variation in PD-L1 positivity.

Association of PD-L1 Expression and Other Variables With Benefit From Immune Checkpoint Inhibition in Advanced Gastroesophageal Cancer: Systematic Review and Meta-analysis of 17 Phase 3 Randomized Clinical Trials

Importance

Approval by the US Food and Drug Administration of immune checkpoint inhibition (ICI) for advanced gastroesophageal cancer (aGEC) irrespective of PD-L1 status has generated controversy. Exploratory analyses from individual trials indicate a lack of meaningful benefit from ICI in patients with absent or low PD-L1 expression; however, analysis of a single variable while ignoring others may not consider the instability inherent in exploratory analyses.

Objective

To systematically examine the predictive value of tissue-based PD-L1 status compared with that of other variables for ICI benefit in aGEC to assess its stability.

Data Sources

MEDLINE, Embase, Scopus, Web of Science, Cochrane Central Register (2000-2022).

Study Selection, Data Extraction, and Synthesis

Randomized clinical trials (RCTs) were included of adults with aGEC (adenocarcinoma [AC] or squamous cell carcinoma [SCC]) randomized to anti-PD-1 or PD-L1-containing treatment vs standard of care (SOC). Study screening, data abstraction, and bias assessment were completed independently by 2 reviewers. Of 5752 records screened, 26 were assessed for eligibility; 17 trials were included in the analysis.

Main Outcomes and Measures

The prespecified primary end point was overall survival. The mean hazard ratio (HR) for ICI vs SOC was calculated (random-effects model). Predictive values were quantified by calculating the ratio of mean HRs between 2 levels of each variable.

Results

In all, 17 RCTs (9 first line, 8 after first line) at low risk of bias and 14 predictive variables were included, totaling 11 166 participants (5067 with SCC, 6099 with ACC; 77.6% were male and 22.4% were female; 59.5% of patients were younger than 65 years, 40.5% were 65 years or older). Among patients with SCCs, PD-L1 tumor proportion score (TPS) was the strongest predictor of ICI benefit (HR, 0.60 [95% CI, 0.53-0.68] for high TPS; and HR, 0.84 [95% CI, 0.75-0.95] for low TPS), yielding a predictive value of 41.0% favoring high TPS (vs ≤16.0% for other variables). Among patients with AC, PD-L1 combined positive score (CPS) was the strongest predictor (after microsatellite instability high status) of ICI benefit (HR, 0.73 [95% CI, 0.66-0.81] for high CPS; and HR, 0.95 [95% CI, 0.84-1.07] for low CPS), yielding a predictive value of 29.4% favoring CPS-high (vs ≤12.9% for other variables). Head-to-head analyses of trials containing both levels of a variable and/or having similar design generally yielded consistent results.

Conclusions and Relevance

Tissue-based PD-L1 expression, more than any variable other than microsatellite instability-high, identified varying degrees of benefit from ICI-containing therapy vs SOC among patients with aGEC in 17 RCTs.

Cost-Effectiveness of Parallel Versus Sequential Testing of Genetic Aberrations for Stage IV Non-Small-Cell Lung Cancer in the Netherlands

PURPOSE

A large number of targeted treatment options for stage IV nonsquamous non–small-cell lung cancer with specific genetic aberrations in tumor DNA is available. It is therefore important to optimize diagnostic testing strategies, such that patients receive adequate personalized treatment that improves survival and quality of life. The aim of this study is to assess the efficacy (including diagnostic costs, turnaround time (TAT), unsuccessful tests, percentages of correct findings, therapeutic costs, and therapeutic effectiveness) of parallel next generation sequencing (NGS)–based versus sequential single-gene–based testing strategies routinely used in patients with metastasized non–small-cell lung cancer in the Netherlands.

METHODS

A diagnostic microsimulation model was developed to simulate 100,000 patients with prevalence of genetic aberrations, extracted from real-world data from the Dutch Pathology Registry. These simulated patients were modeled to undergo different testing strategies composed of multiple tests with different test characteristics including single-gene and panel tests, test accuracy, the probability of an unsuccessful test, and TAT. Diagnostic outcomes were linked to a previously developed treatment model, to predict average long-term survival, quality-adjusted life-years (QALYs), costs, and cost-effectiveness of parallel versus sequential testing.

RESULTS

NGS-based parallel testing for all actionable genetic aberrations is on average €266 cheaper than single-gene–based sequential testing, and detects additional relevant targetable genetic aberrations in 20.5% of the cases, given a TAT of maximally 2 weeks. Therapeutic costs increased by €8,358, and 0.12 QALYs were gained, leading to an incremental cost-effectiveness ratio of €69,614/QALY for parallel versus sequential testing.

CONCLUSION

NGS-based parallel testing is diagnostically superior over single-gene–based sequential testing, as it is cheaper and more effective than sequential testing. Parallel testing remains cost-effective with an incremental cost-effectiveness ratio of 69,614 €/QALY upon inclusion of therapeutic costs and long-term outcomes.