KEYNOTE-042 and the role for single agent pembrolizumab in patients with PD-L1 tumor proportion score 1-49

Biomarker development for PD-(L)1 axis inhibition: a consensus view from the SITC Biomarkers Committee

Therapies targeting the programmed cell death protein-1/programmed death-ligand 1 (PD-L1) (abbreviated as PD-(L)1) axis are a significant advancement in the treatment of many tumor types. However, many patients receiving these agents fail to respond or have an initial response followed by cancer progression. For these patients, while subsequent immunotherapies that either target a different axis of immune biology or non-immune combination therapies are reasonable treatment options, the lack of predictive biomarkers to follow-on agents is impeding progress in the field. This review summarizes the current knowledge of mechanisms driving resistance to PD-(L)1 therapies, the state of biomarker development along this axis, and inherent challenges in future biomarker development for these immunotherapies. Innovation in the development and application of novel biomarkers and patient selection strategies for PD-(L)1 agents is required to accelerate the delivery of effective treatments to the patients most likely to respond.

PD-L1 Expression by RNA-Sequencing in Non-Small Cell Lung Cancer: Concordance with Immunohistochemistry and Associations with Pembrolizumab Treatment Outcomes

Programmed cell death ligand (PD-L1) expression by immunohistochemistry (IHC) lacks sensitivity for pembrolizumab immunotherapy selection in non-small cell lung cancer (NSCLC), particularly for tumors with low expression. We retrospectively evaluated transcriptomic PD-L1 by mRNA next-generation sequencing (RNA-seq). In an unselected NSCLC patient cohort (n = 3168) tested during standard care (2017-2021), PD-L1 IHC and RNA-seq demonstrated moderate concordance, with 80% agreement overall. Most discordant cases were either low or negative for PD-L1 expression by IHC but high by RNA-seq. RNA-seq accurately discriminated PD-L1 IHC high from low tumors by receiver operator curve (ROC) analysis but could not distinguish PD-L1 IHC low from negative tumors. In a separate pembrolizumab monotherapy cohort (n = 102), NSCLC tumors classified as PD-L1 high versus not high by RNA-seq had significantly improved response, progression-free survival, and overall survival as an individual measure and in combination with IHC high or low status. PD-L1 IHC status (high or low) trended toward but had no significant associations with improved outcomes. Conventional PD-L1 IHC testing has inherent limitations, making it an imperfect reference standard for evaluating novel testing technologies. RNA-seq offers an objective PD-L1 measure that could represent a complementary method to IHC to improve NSCLC patient selection for immunotherapy.

NK cell activity and methylated HOXA9 ctDNA as prognostic biomarkers in patients with non-small cell lung cancer treated with PD-1/PD-L1 inhibitors

BACKGROUND

PD-1/PD-L1 inhibitors have improved survival for patients with non-small cell lung cancer (NSCLC). We evaluated natural killer cell activity (NKA) and methylated HOXA9 circulating tumor DNA (ctDNA) as prognostic biomarkers in NSCLC patients treated with PD-1/PD-L1 inhibitors.

METHODS

Plasma was prospectively collected from 71 NSCLC patients before treatment with PD-1/PD-L1 inhibitors and before cycles 2-4. We used the NK Vue^® assay to measure the level of interferon gamma (IFNγ) as a surrogate for NKA. Methylated HOXA9 was measured by droplet digital PCR.

RESULTS

A score combining NKA and ctDNA status measured after one treatment cycle had a strong prognostic impact. Group 1 had IFNγ < 250 pg/ml and detectable ctDNA (n = 27), group 2 consisted of patients with either low levels of IFNγ and undetectable ctDNA or high levels of IFNγ and detectable ctDNA (n = 29), group 3 had IFNγ ≥250 pg/ml and undetectable ctDNA (n = 15). Median OS was 221 days (95% CI 121-539 days), 419 days (95% CI 235-650 days), and 1158 days (95% CI 250 days-not reached), respectively (P = 0.002). Group 1 had a poor prognosis with a hazard ratio of 5.560 (95% CI 2.359-13.101, n = 71, P < 0.001) adjusting for PD-L1 status, histology, and performance status.

CONCLUSIONS

Combining NKA and ctDNA status after one cycle of treatment was prognostic in patients with NSCLC treated with PD-1/PD-L1 inhibitors.

Tumor Immunology and Immunotherapy of Non-Small-Cell Lung Cancer

Historically, non-small-cell lung cancer (NSCLC) has been regarded as a nonimmunogenic tumor; however, recent studies have shown that NSCLCs are among the most responsive cancers to monoclonal antibody immune checkpoint inhibitors (ICIs). ICIs have dramatically improved clinical outcomes for a subset of patients (∼20%) with locally advanced and metastatic NSCLC, and they have also demonstrated promise as neoadjuvant therapy for early-stage resectable disease. Nevertheless, the majority of patients with NSCLC are refractory to ICIs for reasons that are poorly understood. Thus, major questions are: how do we initially identify the patients most likely to derive significant clinical benefit from these therapies; how can we increase the number of patients benefiting; what are the mechanisms of primary and acquired resistance to immune-based therapies; are there additional immune checkpoints besides PD-1/PD-L1 and CTLA-4 that can be targeted to provide greater clinical benefit to patients; and how do we best combine ICI therapy with surgery, radiotherapy, chemotherapy, and targeted therapy? To answer these questions, we need to deploy the latest technologies to study tumors and their microenvironment and how they interact with components of the innate and adaptive immune systems. There is also a need for new preclinical model systems to investigate the molecular mechanisms of resistance to treatment and identify novel therapeutic targets. Recent advances in technology are beginning to shed new light on the immune landscape of NSCLC that may uncover biomarkers of response and maximize the clinical benefit of immune-based therapies. Identification of the mechanisms of resistance should lead to the identification of novel targets and the generation of new therapeutic strategies that improve outcomes for a greater number of patients. In the sections below, we discuss the results of studies examining the immune microenvironment in NSCLC, summarize the clinical experience with immunotherapy for NSCLC, and review candidate biomarkers of response to these agents in NSCLC.

Immunotherapy in Patients with Advanced Non-Small Cell Lung Cancer Lacking Driver Mutations and Future Perspectives

From a complete literature review, we were able to present in this paper what is most current in the treatment with immunotherapy for advanced non-small cell lung cancer (NSCLC). Especially the use of immunotherapy, particularly inhibitors of PD-1 (programmed cell death protein 1), PDL-1 (programmed cell death protein ligand 1), and CTLA-4 (cytotoxic T-lymphocyte antigen 4). Since 2015, these drugs have transformed the treatment of advanced NSCLC lacking driver mutations, evolving from second-line therapy to first-line, with excellent results. The arrival of new checkpoint inhibitors such as cemiplimab and the use of checkpoint inhibitors earlier in the therapy of advanced and metastatic cancers has been making the future prospects for treating NSCLC lacking driver mutations more favorable and optimistic. In addition, for those patients who have low PDL-1 positivity tumors, the combination of cytotoxic chemotherapy, VEGF inhibitor, and immunotherapy have shown an important improvement in global survival and progression free survival regardless the PDL-1 status. We also explored the effectiveness of adding radiotherapy to immunotherapy and the most current results about this combination. One concern that cannot be overlooked is the safety profile of immune checkpoint inhibitors (ICI) and the most common toxicities are described throughout this paper as well as tumor resistance to ICI.

Status of Programmed Death Ligand 1 (PD-L1) by Immunohistochemistry and Scoring Algorithms

The detection of the Programmed Death Ligand 1 (PD-L1) protein by immunohistochemistry is currently the only approved test predictive of response to drugs targeting the PD1/PDL1 axis. The role of this test is debated since several reagents have been used as companion diagnostics for different drugs on diverse immunostaining platforms. In addition, different scoring systems for PD-L1 immunohistochemistry have been applied in the registration studies regarding single drugs. This review deals with the various issues that are related to the immunohistochemical test for PD-L1. We discuss currently unsolved problems such as the advantages and the flaws of PD-L1 immunohistochemistry; the choice of the best reagents and the best scoring system. Finally, we review the current experiences on the role of immunohistochemistry for PD-L1 in clinical trials with immune checkpoint inhibitors.