Integration of peripheral blood- and tissue-based biomarkers of response to immune checkpoint blockade in urothelial carcinoma.

As predictive biomarkers of response to immune checkpoint inhibitors (ICIs) remain a major unmet clinical need in patients with urothelial carcinoma (UC), we sought to identify tissue-based immune biomarkers of clinical benefit to ICIs using multiplex immunofluorescence and to integrate these findings with previously identified peripheral blood biomarkers of response. Fifty-five pretreatment and 12 paired on-treatment UC specimens were identified from patients treated with nivolumab with or without ipilimumab. Whole tissue sections were stained with a 12-plex mIF panel, including CD8, PD-1/CD279, PD-L1/CD274, CD68, CD3, CD4, FoxP3, TCF1/7, Ki67, LAG-3, MHC-II/HLA-DR, and pancytokeratin+SOX10 to identify over three million cells. Immune tissue densities were compared to progression-free survival (PFS) and best overall response (BOR) by RECIST version 1.1. Correlation coefficients were calculated between tissue-based and circulating immune populations. The frequency of intratumoral CD3+ LAG-3+ cells was higher in responders compared to nonresponders (p = 0.0001). LAG-3+ cellular aggregates were associated with response, including CD3+ LAG-3+ in proximity to CD3+ (p = 0.01). Exploratory multivariate modeling showed an association between intratumoral CD3+ LAG-3+ cells and improved PFS independent of prognostic clinical factors (log HR -7.0; 95% confidence interval [CI] -12.7 to -1.4), as well as established biomarkers predictive of ICI response (log HR -5.0; 95% CI -9.8 to -0.2). Intratumoral LAG-3+ immune cell populations warrant further study as a predictive biomarker of clinical benefit to ICIs. Differences in LAG-3+ lymphocyte populations across the intratumoral and peripheral compartments may provide complementary information that could inform the future development of multimodal composite biomarkers of ICI response. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Pancreas cancer: Therapeutic trials in metastatic disease.

Metastatic pancreatic ductal adenocarcinoma (PDAC) is a major cause of cancer-related mortality in 2021. Cytotoxic therapies are the therapeutic mainstay for PDAC. The recent approval of olaparib as maintenance therapy for germline BRCA1/2-mutated PDAC and pembrolizumab for mismatch repair deficient PDAC represent molecularly targeted approaches for this disease. Investigational therapeutic strategies include targeting the stroma, metabolism, tumor microenvironment, and the immune system, and selected approaches are reviewed herein.

Postneoadjuvant adjuvant chemotherapy in resected N1 non-small cell lung cancer with residual nodal disease.

BACKGROUND AND OBJECTIVES: Nodal positivity following neoadjuvant chemotherapy in locally advanced non-small cell lung cancer (NSCLC) is considered a poor prognostic sign, but little data are available on the efficacy of adjuvant chemotherapy in these cases. This analysis sought to determine whether adjuvant chemotherapy was associated with increased survival in NSCLC patients with residual N1 disease at resection. METHODS: Patients from the National Cancer Database (NCDB) with cN1T1-2M0 NSCLC treated with neoadjuvant chemotherapy and definitive resection between 2006 and 2012 were identified. Treatment groups were defined as those receiving no additional therapy or adjuvant chemotherapy ± radiation after resection. Five-year overall survival (OS) was estimated for each group. Cox proportional hazard regression was used to estimate hazard ratios adjusting for demographic, clinical, and facility characteristics. RESULTS: Among 90 eligible patients, 5-year OS was 43% and 56% for patients receiving adjuvant chemotherapy and no additional treatment, respectively (P < 0.56). With multivariable analysis, the estimated hazard ratio was 0.61 (95% CI: 0.61-2.64, P = 0.51) for adjuvant chemotherapy compared to no additional therapy. CONCLUSION: This analysis suggests that adjuvant chemotherapy is not associated with increased survival in NSCLC patients with pathologic N1 NSCLC following neoadjuvant chemotherapy and resection.

A General Approach to Patients Presenting With Locally Advanced or Distant Metastatic Disease.

ABSTRACT: The widespread adoption of immune checkpoint inhibitors and small molecule inhibitors of the MAP kinase pathway has transformed the management of locally advanced and metastatic melanoma. Here, we provide a broad overview on the use of these agents in the first-line setting, incorporating a review of the clinical literature as well as the practice patterns of our respective melanoma groups. Throughout, we highlight areas of uncertainty that provide opportunities for future clinical investigation and additional improvement in outcomes for patients with melanoma.

Spatial Immunophenotyping from Whole-Slide Multiplexed Tissue Imaging Using Convolutional Neural Networks.

The multiplexed immunofluorescence (mIF) platform enables biomarker discovery through the simultaneous detection of multiple markers on a single tissue slide, offering detailed insights into intratumor heterogeneity and the tumor-immune microenvironment at spatially resolved single cell resolution. However, current mIF image analyses are labor-intensive, requiring specialized pathology expertise which limits their scalability and clinical application. To address this challenge, we developed CellGate, a deep-learning (DL) computational pipeline that provides streamlined, end-to-end whole-slide mIF image analysis including nuclei detection, cell segmentation, cell classification, and combined immuno-phenotyping across stacked images. The model was trained on over 750,000 single cell images from 34 melanomas in a retrospective cohort of patients using whole tissue sections stained for CD3, CD8, CD68, CK-SOX10, PD-1, PD-L1, and FOXP3 with manual gating and extensive pathology review. When tested on new whole mIF slides, the model demonstrated high precision-recall AUC. Further validation on whole-slide mIF images of 9 primary melanomas from an independent cohort confirmed that CellGate can reproduce expert pathology analysis with high accuracy. We show that spatial immuno-phenotyping results using CellGate provide deep insights into the immune cell topography and differences in T cell functional states and interactions with tumor cells in patients with distinct histopathology and clinical characteristics. This pipeline offers a fully automated and parallelizable computing process with substantially improved consistency for cell type classification across images, potentially enabling high throughput whole-slide mIF tissue image analysis for large-scale clinical and research applications.

Early On-Treatment Assessment of T Cells, Cytokines, and Tumor DNA with Adaptively Dosed Nivolumab + Ipilimumab: Final Results from the Phase 2 ADAPT-IT Study.

PURPOSE: The Adaptively Dosed ImmunoTherapy Trial (ADAPT-IT;NCT03122522) investigated adaptive ipilimumab discontinuation in melanoma based on early radiographic assessment. Initial findings indicated similar effectiveness compared with conventional nivolumab-ipilimumab (nivo-ipi). Exploratory biomarker analyses and final clinical results are now reported. PATIENTS AND METHODS: Patients with unresectable melanoma received two doses of nivo-ipi. Radiographic assessment at Week 6 informed continuation of ipilimumab before nivolumab maintenance. The primary endpoint was overall response rate at Week 12. Plasma was assayed for circulating tumor DNA and 10 cytokines using a multiplex immunoassay. Flow cytometry of peripheral blood mononuclear cells was performed with an 11-color panel. RESULTS: Among the treated patients, expansion of proliferating T-cell populations was observed in responders and nonresponders. Baseline IL6 levels were low in patients achieving an objective radiographic response (median 1.30 vs. 2.86 pg/mL; P = 0.025). High baseline IL6 levels were associated with short progression-free survival [PFS; HR = 1.24, 95% confidence interval (CI), 1.01-1.52; P = 0.041]. At Week 6, patients with response had lower average tumor variant allele fractions than nonresponders (median 0.000 vs. 0.019; P = 0.014). Greater increases in average variant allele fractions from baseline to Week 6 correlated with short PFS (HR = 1.11, 95% CI, 1.01-1.21; P = 0.023). Week 12 overall response rate was 47% (95% CI, 35%-59%) with a median follow-up of 34 months among survivors. Median PFS was 21 months (95% CI, 10-not reached); 76% of responses (95% CI, 64%-91%) persisted at 36 months. CONCLUSIONS: Adaptively dosed nivo-ipi responses are durable and resemble historical data for conventional nivo-ipi. Baseline IL6 and circulating tumor DNA changes during treatment warrant further study as biomarkers of nivo-ipi response.

CD16+ Macrophages: An Emerging Biomarker for Combined CTLA-4 and PD-1 Blockade.

In a retrospective analysis of patients with unresectable melanoma, higher pretreatment tissue densities of CD16+ macrophages were associated with clinical benefit from combined CTLA-4 and PD-1 blockade. With further validation, this biomarker could serve as a tool in selecting between immune checkpoint inhibitor regimens. See related article by Lee et al., p. 2513.

Adjuvant PD-1 Blockade in Resected Melanoma: Is Preventing Recurrence Enough?

SUMMARY: Grossmann and colleagues report the results of a large randomized trial demonstrating improved recurrence-free survival with adjuvant pembrolizumab in resected melanoma compared with adjuvant ipilimumab or IFNα2b. However, it remains unclear whether adjuvant immunotherapies extend overall survival as outcomes for patients with advanced melanoma continue to improve. See related article by Grossmann et al., p. 644 (1).

Facts and Hopes in Prediction, Diagnosis, and Treatment of Immune-Related Adverse Events.

Over the past decade, the use of immune checkpoint inhibitors (ICI) has expanded across a wide spectrum of oncology indications. Immune-related adverse events (irAE) from ICIs represent a significant source of morbidity, and in rare instances, can lead to treatment-related mortality. There are significant opportunities to better identify patients at increased risk for immune-related toxicity, diagnose irAEs more accurately and earlier in their course, and develop more individualized therapeutic strategies once complications arise. Clinical characteristics, germline and somatic genetic features, microbiome composition, and circulating biomarkers have all been associated with higher risk of developing irAEs in retrospective series. Many of these data suggest that both antitumor and anti-host ICI-associated immune reactions may be driven by common features of either the tumor or the patient's preexisting immune milieu. While irAE diagnosis is currently based on clinical history, exclusion of alternative etiologies, and sometimes pathologic confirmation, novel blood-based and radiographic assays are in development to identify these complications more precisely. Anecdotal reports and small case series have highlighted the potential role of targeted immunomodulatory agents to treat irAEs, though further prospective investigation is needed to evaluate more rigorously their use in these settings. In this review, we highlight the current state of knowledge about predicting, diagnosing, and treating irAEs with a translational focus and discuss emerging strategies which aim to improve each of these domains.

Ensuring equity in the era of HLA-restricted cancer therapeutics.

In January 2022, the US Food and Drug Administration granted regulatory approval to tebentafusp, a bispecific T cell receptor protein that targets melanoma antigen gp100 in the context of the human leucocyte antigen (HLA) A*0201 allele. This approval generated significant excitement, given the relative paucity of effective systemic therapies for advanced uveal melanoma. More broadly, tebentafusp represents the first T cell receptor agent to improve overall survival in any solid tumor.Although HLA-A*02:01 is the most common allele at this locus overall, its expression varies considerably among ethnic groups. It is most frequently expressed in Europeans, and less commonly in African Americans and people of Asian or Pacific Island ancestry. While uveal melanoma is most common in Caucasian populations, other HLA-restricted cancer therapeutics are being developed for indications with more diverse patient populations, such as cervical cancer.We advocate for proactive consideration of the populations eligible for each HLA-restricted therapeutic in development to ensure this emerging therapeutic class does not compound long-standing health disparities. As trials may focus on the most prevalent HLA subtypes, it will take the engagement of multiple stakeholders to ensure equitable access to patients of all ethnic backgrounds.

Adaptive Dosing of Nivolumab + Ipilimumab Immunotherapy Based Upon Early, Interim Radiographic Assessment in Advanced Melanoma (The ADAPT-IT Study).

PURPOSE: Nivolumab + ipilimumab (nivo + ipi) is highly efficacious but has high toxicity. Standard treatment in advanced melanoma is four doses of nivo + ipi followed by nivo alone. Whether four doses of nivo + ipi are needed is unclear. METHODS: The Adaptively Dosed ImmunoTherapy Trial (ADAPT-IT) study (NCT03122522) is a multicenter, single-arm phase II clinical trial. Patients received two doses of nivo (1 mg/kg) + ipi (3 mg/kg) followed by a computed tomography scan at week 6. Patients without new lesions or index lesion tumor growth of > 4% had protocol-defined early favorable antitumor effect (FATE) and ceased nivo + ipi, transitioning to nivo monotherapy. Patients without FATE at week 6 received the standard third and fourth doses of nivo + ipi followed by nivo monotherapy. The primary end point was response rate by RECIST 1.1 at week 12. Secondary end points included additional efficacy assessments and safety. RESULTS: Sixty patients were enrolled; 41 patients (68%) had FATE at week 6 and met criteria for stopping nivo + ipi. Best overall response rates by RECIST at week 12 or any time afterward were 48% (95% CI, 35 to 62) and 58% (95% CI, 45 to 71), respectively. With a median follow-up of 25 months, the estimated 18-month progression-free survival and overall survival are 52% and 80%, respectively. Fifty seven percent of patients had grade 3-5 treatment-related toxicity. CONCLUSION: The efficacy and toxicity of standard four dose nivo + ipi induction therapy in melanoma is likely driven by the first two doses. An interim computed tomography scan after two doses guided cessation of combination dosing and identified almost all responders. Longer follow-up and further study are needed to fully understand the implications of a shortened induction course of nivo + ipi.

Factors Determining Long-Term Antitumor Responses to Immune Checkpoint Blockade Therapy in Melanoma.

With the increasing promise of long-term survival with immune checkpoint blockade (ICB) therapies, particularly for patients with advanced melanoma, clinicians and investigators are driven to identify prognostic and predictive factors that may help to identify individuals who are likely to experience durable benefit. Several ICB combinations are being actively developed to expand the armamentarium of treatments for patients who may not achieve long-term responses to ICB single therapies alone. Thus, negative predictive markers are also of great interest. This review seeks to deepen our understanding of the mechanisms underlying the durability of ICB treatments. We will discuss the currently available long-term data from the ICB clinical trials and real-world studies describing the survivorship of ICB-treated melanoma patients. Additionally, we explore the current treatment outcomes in patients rechallenged with ICB and the patterns of ICB resistance based on sites of disease, namely, liver or CNS metastases. Lastly, we discuss the landscape in melanoma in the context of prognostic or predictive factors as markers of long-term response to ICB.

Checkpoint Blockade in Melanoma Patients With Underlying Chronic Lymphocytic Leukemia.

Chronic lymphocytic leukemia (CLL) is associated with immune dysfunction and an increased risk of melanoma. For patients with metastatic melanoma, immunotherapy with checkpoint blocking antibodies is a standard of care. In patients with concomitant CLL and metastatic melanoma, it is not known whether CLL might influence the antimelanoma efficacy or immune-related toxicities of immune checkpoint blockade. Fifteen patients with locally advanced or metastatic melanoma and a concomitant diagnosis of CLL who received pembrolizumab or ipilimumab with or without nivolumab for the treatment of their melanoma at Memorial Sloan Kettering Cancer Center between January 1, 2010, and January 1, 2017, were retrospectively identified. Clinical characteristics including absolute lymphocyte counts during therapy were recorded along with a response to treatment (objective radiographic response, progression-free survival, and adverse events) for each patient. Of 9 response-evaluable patients treated with ipilimumab, 3 (33%) had a partial response, 1 (11%) had stable disease, and 5 (56%) developed progressive disease. Objective tumor responses were also observed with single-agent therapy pembrolizumab and with combination therapy of nivolumab and ipilimumab. Grade 3 or 4 toxicity was observed in 6 of 15 patients (40%), including diarrhea, transaminitis, rash, and hemolytic anemia. Although our retrospective assessment was limited, there was no evidence that CLL responded to the checkpoint blockade. This case series demonstrates that ipilimumab, pembrolizumab, and combined ipilimumab and nivolumab therapies show clinical activity in patients with melanoma and concomitant CLL, at rates consistent with those previously reported. This population may warrant closer surveillance for hematologic immune-related toxicities such as autoimmune hemolytic anemia.

Multiplex quantitative analysis of cancer-associated fibroblasts and immunotherapy outcome in metastatic melanoma.

BACKGROUND: The cancer-associated fibroblast (CAF) population is implicated in immune dysregulation. Here, we test the hypothesis that CAF profiles in pretreatment tumor specimens are associated with response to immune checkpoint blockade of programmed cell death 1 (PD-1). METHODS: Pretreatment whole tissue sections from 117 melanoma patients treated with anti-PD-1 therapy were assessed by multiplex immunofluorescence to detect CAFs defined by Thy1, smooth muscle actin (SMA), and fibroblast activation protein (FAP). Two independent image analysis technologies were used: inForm software (PerkinElmer) to quantify cell counts, and AQUA™ to measure protein by quantitative immunofluorescence (QIF). CAF parameters by both methodologies were assessed for association with previously measured immune markers (CD3, CD4, CD8, CD20, CD68, PD-L1), best overall response, progression-free survival (PFS), and overall survival (OS). RESULTS: CAF parameters, by cell counts or QIF, did not correlate with immune markers nor with best overall response. However, both Thy1 and FAP cell counts had significant positive associations with PFS (all P < 0.05) and OS (all P < 0.003). SMA cell counts showed negative associations with outcome in anti-PD-1 treated patients. Similar associations were not observed in a control cohort of historical melanoma patients predating immunotherapy. Instead, FAP was a negative prognostic biomarker (P = 0.01) in the absence of immunotherapy. Multivariable analyses revealed significant PFS and OS associations with the CAF parameters were independent of baseline variables. CONCLUSIONS: Pretreatment CAF profiles are associated with melanoma immunotherapy outcome. Multiplex CAF analysis has potential as an objective companion diagnostic in immuno-oncology.

High-Plex Predictive Marker Discovery for Melanoma Immunotherapy-Treated Patients Using Digital Spatial Profiling.

PURPOSE: Protein expression in formalin-fixed, paraffin-embedded tissue is routinely measured by IHC or quantitative fluorescence (QIF) on a handful of markers on a single section. Digital spatial profiling (DSP) allows spatially informed simultaneous assessment of multiple biomarkers. Here we demonstrate the DSP technology using a 44-plex antibody cocktail to find protein expression that could potentially be used to predict response to immune therapy in melanoma.Experimental Design: The NanoString GeoMx DSP technology is compared with automated QIF (AQUA) for immune marker compartment-specific measurement and prognostic value in non-small cell lung cancer (NSCLC). Then we use this tool to search for novel predictive markers in a cohort of 60 patients with immunotherapy-treated melanoma on a tissue microarray using a 44-plex immune marker panel measured in three compartments (macrophage, leukocyte, and melanocyte) generating 132 quantitative variables. RESULTS: The spatially informed variable assessment by DSP validates by both regression and variable prognostication compared with QIF for stromal CD3, CD4, CD8, CD20, and PD-L1 in NSCLC. From the 132 variables, 11 and 15 immune markers were associated with prolonged progression-free survival (PFS) and overall survival (OS). Notably, we find PD-L1 expression in CD68-positive cells (macrophages) and not in tumor cells was a predictive marker for PFS, OS, and response. CONCLUSIONS: DSP technology shows high concordance with QIF and validates based on both regression and outcome assessment. Using the high-plex capacity, we found a series of expression patterns associated with outcome, including that the expression of PD-L1 in macrophages is associated with response.

Closed system RT-qPCR as a potential companion diagnostic test for immunotherapy outcome in metastatic melanoma.

BACKGROUND: In melanoma, there is no companion diagnostic test to predict response to programmed cell death 1 (PD-1) axis immune checkpoint inhibitor (ICI) therapy. In the adjuvant setting, only one in five patients may benefit from ICI, so a biomarker is needed to select those that may or may not benefit. Here, we test a new 4-gene multiplex immunotherapy panel with research use only (RUO) prototype mRNA expression profile on the GeneXpert closed system using real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) for association with clinical benefit after treatment with ICI therapy in metastatic melanoma patients. METHODS: Pretreatment formalin-fixed paraffin-embedded (FFPE) tissue sections from melanoma patients treated with anti-PD-1 therapy (pembrolizumab, nivolumab, or ipilimumab plus nivolumab) between 2011 and 17 were selected from the Yale Pathology archives. FFPE sections were macrodissected to enrich for tumor for quantitative assessment of CD274 (PD-L1), PDCD1LG2 (PD-L2), CD8A, and IRF1 by RT-qPCR multiplex mRNA panel. Multiplex panel transcript levels were correlated with clinical benefit (complete response [CR], partial response [PR], stable disease [SD]); disease outcomes (progression-free survival [PFS] and overall survival [OS]); and protein levels assessed by quantitative immunofluorescence (QIF). RESULTS: Transcript levels were significantly higher in responders (CR/PR/SD) than in nonresponders (PD) for CD8A (p = 0.0001) and IRF1 (p = 0.0019). PFS was strongly associated with high CD274 (p = 0.0046), PDCD1LG2 (p = 0.0039), CD8A (p = 0.0002), and IRF1 (p = 0.0030) mRNA expression. Similar associations were observed for OS with high CD274 (p = 0.0004), CD8A (p = 0.0030), and IRF1 (p = 0.0096) mRNA expression. Multivariate analyses revealed significant PFS and OS associations with immunotherapy panel markers independent of baseline variables. Exploratory analyses revealed a novel significant association of high combined CD274 & PDCD1LG2 (L1/L2) transcript expression with PFS (p < 0.0001) and OS (p = 0.0011), which remained significant at a multivariate level for both PFS (HR = 0.31) and OS (HR = 0.39). CONCLUSIONS: Individual immunotherapy panel markers CD274, PDCD1LG2, CD8A, IRF1 and a combined L1/L2 mRNA levels show promising associations with melanoma immunotherapy outcome. The turnaround time of the test (2 h) and easy standardization of the platform makes this an attractive approach for further study in the search for predictive biomarkers for ICI.

Multiplex Quantitative Analysis of Tumor-Infiltrating Lymphocytes and Immunotherapy Outcome in Metastatic Melanoma.

PURPOSE: Because durable response to programmed cell death 1 (PD-1) inhibition is limited to a subset of melanoma patients, new predictive biomarkers could have clinical utility. We hypothesize that pretreatment tumor-infiltrating lymphocyte (TIL) profiles could be associated with response. EXPERIMENTAL DESIGN: Pretreatment whole tissue sections from 94 melanoma patients treated with anti-PD-1 therapy were profiled by multiplex immunofluorescence to perform TIL quantification (CD4, CD8, CD20) and assess TIL activation (CD3, GZMB, Ki67). Two independent image analysis technologies were used: inForm (PerkinElmer) to determine cell counts, and AQUA to measure protein by quantitative immunofluorescence (QIF). TIL parameters by both methodologies were correlated with objective response or disease control rate (ORR/DCR) by RECIST 1.1 and survival outcome. RESULTS: Pretreatment lymphocytic infiltration, by cell counts or QIF, was significantly higher in complete or partial response than in stable or progressive disease, particularly for CD8 (P < 0.0001). Neither TIL activation nor dormancy was associated with outcome. CD8 associations with progression-free survival (HR > 3) were independently significant in multivariable analyses and accounted for similar CD3 associations in anti-PD-1-treated patients. CD8 was not associated with melanoma prognosis in the absence of immunotherapy. Predictive performance of CD8 cell count (and QIF) had an area under the ROC curve above 0.75 (ORR/DCR), which reached 0.83 for ipilimumab plus nivolumab. CONCLUSIONS: Pretreatment lymphocytic infiltration is associated with anti-PD-1 response in metastatic melanoma. Quantitative TIL analysis has potential for application in digital precision immuno-oncology as an "indicative" companion diagnostic.

Immune Marker Profiling and Programmed Death Ligand 1 Expression Across NSCLC Mutations.

INTRODUCTION: Programmed death 1/programmed death ligand 1 (PD-L1) axis inhibitors have been proven effective, especially in patients with tumors expressing PD-L1. Their clinical efficacy in patients with EGFR-activating mutations is still unclear, whereas KRAS mutations seem to be associated with good response. METHODS: We used multiplexed quantitative immunofluorescence to investigate PD-L1 expression and to characterize tumor infiltrating lymphocyte (TIL) populations and their activation status in more than 150 NSCLC patients with known mutation status. RESULTS: PD-L1 expression was significantly lower in EGFR-mutant compared to KRAS-mutant, and EGFR/KRAS wild-type (WT) tumors. KRAS mutant tumors were more inflamed with higher CD4+, CD8+ and CD20+ TILs. Subgroup analysis by TIL activation status revealed that EGFR mutants had a high frequency of inactive TILs even though lymphocytes were present in the tumor microenvironment. In contrast, in KRAS mutants, when TILs were present they were almost always active. Additionally, we found differences between EGFR mutation sites in CD8+ expression and the TIL activation profile. Finally, activated EGFR correlated with increased PD-L1 expression in EGFR mutants but not in EGFR WT, whereas TIL activation was associated with higher PD-L1 only in EGFR/KRAS WT. CONCLUSIONS: Our findings show the unique immune profile of EGFR-mutant tumors. The high frequency of inactive TILs could explain the low immunotherapy response rates in these patients, whereas PD-L1 as a predictive biomarker may reflect the constitutive oncogenic signaling rather than immune signaling, which would be associated with high PD-L1 levels and TILs activation.