Effective retreatment with osimertinib in CNS-relapsed epidermal growth factor receptor-mutant non-small cell lung cancer patient following resection and adjuvant osimertinib.

For years, adjuvant chemotherapy has been the only standard treatment for resected non-small cell lung cancer patients (NSCLC), offering a dismal survival improvement at 5 years. Following the outstanding results of the recent ADAURA trial, osimertinib has become a new standard treatment for resected epidermal growth factor receptor (EGFR)-mutant non-squamous NSCLC, regardless of the administration of chemotherapy. For patients whose disease relapses after completion of the adjuvant therapy, there is no consensus about the optimal treatment. Herein, we report the case of a 74-year-old woman diagnosed with stage IIIA non-squamous NSCLC, harboring the EGFR p.L858R mutation. After complete tumor resection, the patient received adjuvant chemotherapy with cisplatin and vinorelbine, followed by osimertinib 80 mg daily for 3 years within the ADAURA trial. Brain disease relapse was documented 18 months after treatment completion by computed tomography scans. The patient was then retreated with osimertinib obtaining a deep intracranial partial response, which is still lasting after 21 months. The retreatment with osimertinib in patients whose disease relapsed following adjuvant therapy with the third-generation EGFR inhibitor might be a valid option, especially in patients with intracranial disease relapse. Studies are warranted to confirm this finding and to define the impact of the disease-free interval in this regard.

Impact of Baseline Versus Intercurrent Steroids Administration on Upfront Chemo-Immunotherapy for Advanced Non-Small Cell Lung Cancer (NSCLC).

The impact of baseline versus intercurrent steroids on the efficacy of upfront chemotherapy plus pembrolizumab (CT-ICI) for advanced non-small cell lung cancer (NSCLC) patients is unclear. We conducted a retrospective study on metastatic NSCLC patients treated with upfront CT-ICI at our institution between March 2020 and December 2021. The use of steroids was considered as the administration of at least 10 mg of prednisone equivalent. Of 101 patients, 36 (35.6%) received steroid therapy at baseline, and 18 (17.8%) started steroids on treatment. Overall, median progression-free survival (mPFS) was 6.5 months (95% CI, 5.9−8.9) and median overall survival (mOS) was 18.2 months (95% CI, 8.9-NR). Patients taking baseline steroids had significantly shorter survival than those not taking them and those assuming intercurrent steroids (mPFS 5.0 vs. 9.2 vs. 7.3 months, p < 0.001; mOS 7.0 months vs. not reached, p < 0.001). Baseline steroids were significantly associated with poorer survival outcomes in the multivariate model (OS HR 2.94, p = 0.02; PFS HR 3.84, p > 0.001). Conversely, intercurrent prescription did not reach a significant value regardless of other pivotal variables included in the model. Baseline steroid administration was associated with a detrimental effect on survival outcomes in NSCLC patients treated with CT-ICI. The role of intercurrent steroid administration should be further explored in larger studies.

Systemic and liver-directed therapies in metastatic uveal melanoma: state-of-the-art and novel perspectives.

Metastatic uveal melanoma (MUM) is the most common form of noncutaneous melanoma. It is different from its cutaneous counterpart and is characterized by a very poor prognosis. Despite groundbreaking improvements in the treatment of cutaneous melanoma, there have been few advances in the treatment of MUM, and standard treatments for MUM have not been defined. We performed a systematic review focusing our attention on all interventional studies, ongoing or already published, concerning the treatment of MUM. We present results from studies of chemotherapy, targeted therapy, immunotherapy and liver-directed therapies. Although the results in this setting have been disappointing until now, trials investigating novel immunotherapeutic strategies alone and in combination with targeted agents and liver-directed therapies are ongoing.

Phase 2 study of NAB-paclitaxel in SensiTivE and refractory relapsed small cell lung cancer (SCLC) (NABSTER TRIAL).

BACKGROUND: Despite sensitivity to first-line chemotherapy, most small-cell lung cancer (SCLC) patients relapse. In this setting, topotecan demonstrated modest activity with significant toxicity. Paclitaxel was also active. This study was designed to evaluate activity and safety of nab-paclitaxel in relapsed SCLC. METHODS: In this multicentre prospective Phase 2 trial, patients with refractory or sensitive SCLC progressed to first-line platinum-based chemotherapy received nab-paclitaxel 100 mg/smq on days 1, 8, 15 every 4 weeks up to six cycles, progressive disease or intolerable toxicity. Primary endpoint was investigator-assessed objective tumour response. Secondary endpoints were toxicity, progression-free survival (PFS) and overall survival (OS). RESULTS: Of the 68 patients treated, partial response was 8% in the refractory cohort and 14% in the sensitive cohort. Most common toxicities of any grade were fatigue (54%), anaemia (38%), neutropenia (29%), leukopenia (26%) and diarrhoea (21%). Median PFS was similar in both refractory (1.8 months) and sensitive cohorts (1.9 months), while median OS was longer in sensitive one (6.6 versus 3.6 months). CONCLUSIONS: Although nab-paclitaxel has shown some modest anti-tumour activity in relapsed SCLC, associated with a favourable toxicity profile, the primary end-point of the study was not met. CLINICAL TRIAL REGISTRATION: Clinical Trial registration number is ClinicalTrials.gov Identifier: NCT03219762.

Osteoblastic bone response mimicking bone progression during treatment with pembrolizumab in advanced cutaneous melanoma.

Pembrolizumab is an immune checkpoint inhibitor approved for the treatment of patients with unresectable or metastatic melanoma. Appearance of bone metastases, either osteolytic or osteoblastic, during treatment qualifies as disease progression. We report the case of a 64-year-old White woman with a metastatic melanoma undergoing second-line treatment with pembrolizumab. At first evaluation, after 3 months of therapy, computed tomography scans showed the onset of osteosclerotic lesions and a significant reduction in all the previously identified metastases; on the contrary, a fluorine-18-fluorodeoxyglucose PET showed the normalization of fluorine-18-fluorodeoxyglucose uptake in all the baseline lesions, including bone metastases. Osteoblastic response, consisting of occurrence of new osteoblastic lesions on computed tomography imaging, as a consequence of an osteoblastic reaction of previously undetectable bone metastases, has been reported in some cancers that receive treatments such as chemotherapy, hormonal or targeted therapy. However, it had never been reported in patients with melanoma treated with immunotherapy. An apparent worsening of bone imaging on standard computed tomography scan in patients under checkpoint inhibitor should not lead to modification of treatment strategy, because misinterpretation as disease progression may lead to the premature cessation of a beneficial treatment and finally have a negative effect on patients' clinical outcome.

Efficacy and tolerability of capmatinib in a very elderly patient with metastatic NSCLC harboring a MET exon 14 mutation.

We report the case of an 87-year-old female patient who was diagnosed with metastatic non-small-cell lung cancer harboring MET exon 14 skipping mutation (MET ex14) and PD-L1 expression of 60%. A first-line treatment with atezolizumab was started with primary resistance. Then, a second-line treatment with capmatinib, a selective type Ib MET tyrosine kinase inhibitor, was started, achieving a partial response. The patient is still alive and on treatment with capmatinib 300 mg twice daily after 20 months, with a good tolerability and no evidence of disease progression.In summary, our patient experienced a long-lasting response (>18 months) with capmatinib as second-line treatment. Further analyses evaluating the efficacy and tolerability of MET tyrosine kinase inhibitors are warranted, especially in the elderly, a non-small-cell lung cancer population whose tumors could more frequently harbor MET ex14 mutation.

[Box: see text].

Histopathological Evidence for a Non-Inflammatory Mechanism in Osimertinib-Induced Myopathy: A Case Report.

Osimertinib, a third-generation EGFR tyrosine kinase inhibitor, is the standard of care for patients with advanced NSCLC and EGFR-sensitizing mutations. Both in osimertinib pivotal trials and in the post-marketing phase, asymptomatic creatinine phosphokinase elevation and clinically relevant muscle damage have been reported. However, the mechanisms underlying these conditions remain unclear. Herein, we report the first muscle biopsy description of osimertinib-induced myopathy and hypothesize that the mechanisms underpinning muscle toxicity could be driven by hyporegenerative mechanisms and mitochondrial dysfunction with subsequent reduced metabolic endurance, both directly linked to the inhibition of downstream molecular pathways mediated by EGFR in muscle cells.

Predictors of survival to immunotherapy and chemoimmunotherapy in non-small cell lung cancer: A meta-analysis.

BACKGROUND: Many patients with non-small cell lung cancer (NSCLC) derive poor benefit from immunotherapy (IO). For some of them, adding chemotherapy (CT) can improve the outcomes, but the reliability of programmed death-ligand 1 (PD-L1) expression as the only biomarker to distinguish these patients is unsatisfactory. We sought to detect clinicopathological and molecular predictive factors of survival that might be added to PD-L1 expression in the selection of patients who should receive IO alone or chemoimmunotherapy (CIT). METHODS: We conducted a systematic search of randomized controlled clinical trials investigating IO, alone or with CT, vs CT alone in treatment-naïve advanced NSCLC patients. Meta-analyses and meta-regression analyses were performed to investigate IO alone vs CT, CIT vs CT, and IO alone vs CIT. RESULTS: A total of 14 367 patients with advanced NSCLC across 25 randomized controlled clinical trials were included. Squamous histology, male sex, current and former smoker status, PD-L1 expression of 50% or more, and high tumor mutational burden (TMB) correlated with improved survival with IO alone compared with CT. Conversely, female sex, no smoking history, negative PD-L1 expression, and low TMB correlated with unsatisfactory outcomes with IO alone vs CT but not with CIT vs CT. CIT improved survival vs IO alone in female patients, never smokers, those having a PD-L1 expression of 1% or more (but not with a PD-L1 of ≥ 50%) or a low TMB and in patients with central nervous system metastasis. CONCLUSIONS: These findings suggest some clinicopathological and molecular features that, added to PD-L1 expression, could help in the selection of the most appropriate first-line IO-based treatment for advanced NSCLC patients.

Emerging Novel Therapeutic Approaches for Treatment of Advanced Cutaneous Melanoma.

The prognosis of patients with advanced cutaneous melanoma has radically changed in the past decade. Nevertheless, primary or acquired resistance to systemic treatment occurs in many cases, highlighting the need for novel treatment strategies. This review has the purpose of summarizing the current area of interest for the treatment of metastatic or unresectable advanced cutaneous melanoma, including data from recently completed or ongoing clinical trials. The main fields of investigation include the identification of new immune checkpoint inhibitors (anti-LAG3, GITR agonist and anti-TIGIT), adoptive cell therapy, vaccines, engineered TCR therapy, IL-2 agonists, novel targets for targeted therapy (new MEK or RAF inhibitors, HDAC, IDO, ERK, Axl, ATR and PARP inhibitors), or combination strategies (antiangiogenetic agents plus immune checkpoint inhibitors, intra-tumoral immunotherapy in combination with systemic therapy). In many cases, only preliminary efficacy data from early phase trials are available, which require confirmation in larger patient cohorts. A more in-depth knowledge of the biological effects of the molecules and identifying predictive biomarkers remain crucial for selecting patient populations most likely to benefit from novel emerging treatment strategies.

Non-small-cell lung cancer: how to manage RET-positive disease.

Targeted therapy has dramatically changed the history and outcomes of oncogene-addicted non-small-cell lung cancer (NSCLC). RET rearrangements are typically observed in about 1-2% of NSCLC, resulting in constitutive activation of downstream signalling pathways commonly involved in cell growth and survival. RET-positive NSCLCs are generally associated with young age, non-smoking history, a high rate of brain metastases at diagnosis and an immunologically 'cold' tumour microenvironment. Multi-kinase inhibitors, such as cabozantinib, lenvatinib and vandetanib, showed limited efficacy but significant toxicity mainly linked to off-target effects. In contrast, two RET-selective tyrosine kinase inhibitors (TKIs), selpercatinib and pralsetinib, demonstrated high response rates and manageable safety profiles, and have received FDA approval for the treatment of advanced RET-positive NSCLC regardless of previous lines of treatment. Despite the initial high response rate to RET-TKIs, most patients inevitably develop disease progression due to acquired resistance mechanisms by both on-target or off-target mechanisms. To date, new potent and selective next-generation RET-TKIs are currently being evaluated in ongoing clinical trials in order to overcome resistance and improve efficacy and blood-brain barrier crossing. Genomic recharacterization at progression could help guide treatment choice or enrolment in clinical trials of specific next-generation RET inhibitors. Here, we review the biology, clinicopathological characteristics, targeted therapies and mechanisms of resistance of advanced NSCLC harbouring RET fusions to provide treatment guidance for these patients.

Genomic Landscape, Clinical Features and Outcomes of Non-Small Cell Lung Cancer Patients Harboring BRAF Alterations of Distinct Functional Classes.

BACKGROUND: In non-small cell lung cancer (NSCLC), BRAF class 1 alterations are effectively targeted by BRAF inhibitors. Conversely, targeted therapies have very low or absent activity in patients carrying class 2 and 3 alterations. The spectrum of BRAF alterations in NSCLC patients, and their accompanying clinical features, genomic landscape and treatment outcomes have been poorly reported. PATIENTS AND METHODS: We identified BRAF alterations of defined functional class across different tumors through a systematic review. Then, we selected NSCLC patients carrying BRAF alterations, according to the systematic review, in the cBioPortal (cBioPortal cohort) to collect and analyze clinical, biomolecular and survival data. Finally, we identified NSCLC patients carrying BRAF non-V600 mutations enrolled in POPLAR and OAK trials (POPLAR/OAK cohort), extracting clinical and survival data for survival analyses. RESULTS: 100 different BRAF non-V600 alterations were identified through the systematic review. In the cBioPortal cohort (n = 139), patients harboring class 2 and 3 alterations were more frequently smokers and had higher tumor mutational burden compared to those carrying class 1 alterations. The spectrum of most frequently co-altered genes was significantly different between BRAF alterations classes, including SETD2, STK11, POM121L12, MUC16, KEAP1, TERT, TP53 and other genes. In the POPLAR/OAK cohort, patients carrying non-V600 BRAF alterations were characterized by poor prognosis compared to BRAF wild-type patients. CONCLUSIONS: Different classes of BRAF alterations confer distinctive clinical features, biomolecular signature and disease behavior to NSCLC patients. Non-V600 alterations are characterized by poor prognosis, but key gene co-alterations involved in cancer cell survival and immune pathways may suggest their potential sensitivity to tailored treatments.

The Palliative Prognostic (PaP) Score without Clinical Evaluation Predicts Early Mortality among Advanced NSCLC Patients Treated with Immunotherapy.

Background: An acceptable risk-benefit ratio may encourage the prescription of immune checkpoint inhibitors (ICI) near the late stage of life. The lung immune prognostic index (LIPI) was validated in advanced non-small cell lung cancer (NSCLC) patients treated with ICIs. The palliative prognostic (PaP) score without clinical prediction of survival (PaPwCPS) predicts early mortality probability in terminal cancer patients. Methods: We performed a retrospective study including 182 deceased advanced NSCLC patients, treated with single-agent ICI at our Institution. Two prognostic categories of high and low mortality risk were identified through ROC curve analysis for PaPwCPS and LIPI scores. Results: Most were >65 years of age (68.3%) and received second-line ICI (61.2%). A total of 29 (15.9%) and 131 (72.0%) patients died within 30 and 90 days from treatment start, respectively. A total of 81 patients (44.5%) received ICI during the last month of life. Baseline PaPwCPS and LIPI scores were assessable for 78 patients. The AUC of ROC curves was significantly increased for PaPwCPS as compared with LIPI score for both 30-day and 90-day mortality. A high PaPwCPS score was associated in multivariate analysis with increased 30-day (HR 2.69, p = 0.037) and 90-day (HR 4.01, p < 0.001) mortality risk. A high LIPI score was associated with increased 90-day mortality risk (p < 0.001). Conclusion: We found a tendency towards ICI prescription near the late stage of life. The PaPwCPS score was a reliable predictor of 30- and 90-day mortality.

Clinical characteristics and treatment outcomes of non-V600 E/K BRAF mutant melanoma patients: a single-institution experience.

The widespread use of more sensitive detection tools, such as next-generation sequencing, has increased the identification of a variety of BRAF mutations other than V600E/K in melanoma patients. However, there is a lack of established data regarding the efficacy of BRAF/MEK inhibitors and immune-checkpoint immune inhibitors (ICI) for these patients. We performed a retrospective study, including all the patients diagnosed with stage III or IV melanoma that were referred to the University Hospital of Bologna from 2011 to 2021, carrying a non-V600E or V600K mutation of BRAF and who were started on systemic treatment. We found 14 patients with stage III or IV melanoma harboring the following BRAF mutations: V600R, V600_K601delinsE, K601E, p.T599_V600insT, L597V, G466R, S467L, and A598T. Of note, G466R and A598T BRAF mutations have never been previously reported in melanoma. Four patients received combined BRAF/MEK inhibitors, two patients BRAF inhibitor monotherapy, and six patients were treated with ICI for advanced melanoma; four patients received adjuvant treatment with nivolumab. Given the few cases and the absence of randomized clinical trials, it is important to report clinical experiences, which can guide physicians in the treatment of melanomas harboring rare BRAF mutations.

Patterns of renal toxicity from the combination of pemetrexed and pembrolizumab for advanced nonsquamous non-small-cell lung cancer (NSCLC): A single-center experience.

OBJECTIVES: The combination of immune-checkpoint inhibitors (ICI) and platinum-pemetrexed chemotherapy (CT) in first-line setting improved survival outcomes of advanced non-small cell lung cancer (NSCLC) patients. Among the various adverse events, renal toxicity can be a relevant safety issue. MATERIALS AND METHODS: We conducted a single-center, observational retrospective study including consecutive patients treated with upfront CT-ICI for advanced nonsquamous NSCLC to investigate incidence and clinical characteristics of acute kidney injury (AKI) using 'Acute Kidney Injury Working Group of Kidney Disease: Improving Global Outcomes' (KDIGO) definition. RESULTS: A total of 89 patients received a first-line CT/ICI. The median age was 69 years. 60.7 % were male, and 87.6 % had an ECOG PS of 0-1. 92.1 % had a baseline glomerular filtration rate of at least 60 ml/min. According to KDIGO criteria, 25 (28 %) patients developed AKI. Considering risk factors for AKI onset, patients receiving >10 cycles of CT/ICI were more likely to experience AKI (p < 0.001). No other associations were found with other variables, including concomitant medications. Any component of the treatment was discontinued (pemetrexed pembrolizumab or both) in 10 (40 %) patients, and 9 patients (36 %) were addressed to nephrological consultation. These patients had higher mean creatinine variation from baseline (1 vs 0.6 mg/dl, p = 0.025) and creatine level (1.8 vs 1.4 mg/dl, p = 0.015), but lower eGFR (35.7 vs 54.2 ml/min, p = 0.011) in comparison to patients not addressed. No patients had microscopic hematuria or pyuria, but mild proteinuria (<0.8 g/24 h) was found in 4 patients. A renal biopsy was performed on 3 patients, revealing acute tubule interstitial nephritis (ATIN), karyomegalic interstitial nephritis, and acute tubular necrosis (ATN). CONCLUSION: Renal toxicity represents a challenging adverse event that could negatively impact outcomes of metastatic nonsquamous NSCLC patients receiving CT/ICI demanding a multidisciplinary approach.

Multicenter Observational Study on Metastatic Non-Small Cell Lung Cancer Harboring BRAF Mutations: Focus on Clinical Characteristics and Treatment Outcome of V600E and Non-V600E Subgroups.

INTRODUCTION: BRAF mutation involved 2-4% of lung adenocarcinoma. Differences in clinicopathologic features and patient outcome exist between V600E and non-V600E BRAF mutated NSCLC. Thus, we sought to assess the frequency and clinical relevance of BRAF mutations in a real-life population of advanced-NSCLC, investigating the potential prognostic significance of distinct genetic alterations. MATERIALS AND METHODS: The present multicenter Italian retrospective study involved advanced BRAF mutant NSCLC. Complete clinicopathologic data were evaluated for BRAF V600E and non-V600E patients. RESULTS: A total of 44 BRAFmut NSCLC patients were included (V600E, n = 23; non-V600E, n = 21). No significant differences in survival outcome and treatment response were documented, according to V600E vs. non-V600E mutations, although a trend towards prolonged PFS was observed in the V600E subgroup (median PFS = 11.3 vs. 6.0 months in non-V600E). In the overall population, ECOG PS and age significantly impacted on OS, while bone lesions were associated with shorter PFS. Compared to immunotherapy, first-line chemotherapy was associated with longer OS in the overall population, and especially in the BRAF V600E subtype. CONCLUSIONS: Here, we report on real-life data from a retrospective cohort of advanced-NSCLC harboring BRAF alterations. Our study offers relevant clues on survival outcome, therapeutic response, and clinicopathologic correlations of BRAF-mutant NSCLC.

Therapeutic Outcomes and Clinical Features of Advanced Non-Small Cell Lung Cancer Carrying KRAS Mutations: A Multicenter Real-life Retrospective Study.

INTRODUCTION: Targeting Kirsten Rat Sarcoma (KRAS) has been deemed impossible for long time, but new drugs have recently demonstrated promising results. Evidence on the outcome of KRAS-mutant advanced-NSCLC treated with new standard regimens are still scarce. Thus, we aimed at assessing the incidence and clinical impact of KRAS mutations in a real-life population of advanced-NSCLC, exploring the prognostic significance of distinct alterations. MATERIALS AND METHODS: The present multicenter retrospective study, conducted by 5 Italian Centers from January 2018 to February 2020, involved 297 advanced KRAS mutant NSCLC. Complete clinico-pathological data were evaluated. RESULTS: Out of 297 patients, 130 carried KRAS_G12C mutation, while 167 presented with mutations other than G12C. Within KRAS_non-G12C group, 73%, 16.8% and 8.9% harboured G12X, codon 13 and Q61H alterations, respectively. No significant differences in survival outcome and treatment response were documented according to KRAS_G12C versus non-G12C, nor KRAS_G12C versus G12X versus other mutations. On univariate analysis ECOG PS, number and sites of metastatic lesions and PD-L1 status significantly impacted on survival. A clear trend towards worse prognosis was apparent in chemotherapy-treated patients, while immunotherapy-based regimens were associated to prolonged survival. Investigating the outcome of PD-L1 ≥ 50% population, we did not detect any significant difference between KRAS_G12C and non-G12C subsets. CONCLUSION: Here, we report on real-life data from a large retrospective cohort of advanced NSCLC harbouring KRAS alterations, with particular attention to G12C mutation. Our study offers useful clues on survival outcome, therapeutic response and clinico-pathological correlations in KRAS-mutant setting, especially in the upcoming era of KRAS G12C targeting therapy.

BRAF-mutated malignant melanoma with chondrosarcomatous differentiation in inguinal nodal metastasis.

We report the case of a young woman who developed metastatic melanoma in the inguinal nodal region, which acquired chondrosarcomatous differentiation and preserved the BRAF mutation found in the primary tumor. The patient was treated with a BRAF/MEK inhibitor combination therapy (dabrafenib/trametinib), which was demonstrated to be effective and well-tolerated.

Cutaneous and Mucosal Melanomas of Uncommon Sites: Where Do We Stand Now?

Melanomas arising at uncommon sites include a group of lesions related to unusual localizations in specific ethnic groups. The rarity of the disease often represents a limit to the participation of patients in specific trials. However, this peculiar genetic scenario has important therapeutic implications regarding new oncologic therapies. The aim of this article is to review the clinical features, somatic alterations and therapeutic options for melanomas of uncommon sites. They can be classified as cutaneous and mucosal lesions affecting the nail apparatus, palms/soles, oral mucosa, genital area and scalp. The prognosis may be worse compared to melanomas of other districts, and a prompt diagnosis may dramatically influence the outcome. Dermatologists and oncologists should therefore distinguish this melanoma subgroup in terms of surgical intervention and medical treatment. Due to the lack of mutations in genes usually found in cutaneous melanomas, the discovery of novel targets is required to develop new strategies and to change the prognosis of non-responders or wild-type patients.

PD-L1 Expression in Circulating Tumor Cells as a Promising Prognostic Biomarker in Advanced Non-small-cell Lung Cancer Treated with Immune Checkpoint Inhibitors.

BACKGROUND: Circulating tumor cells (CTCs) are a promising source of biological information in cancer. Data correlating PD-L1 expression in CTCs with patients' response to immune checkpoint inhibitors (ICIs) in non-small-cell lung cancer (NSCLC) are still lacking. METHODS: This is a prospective single-center cohort study enrolling patients with advanced NSCLC. CTCs were identified and counted with the CellSearch system. PD-L1 expression on CTCs was assessed with phycoerythrin-conjugated anti-human PD-L1 antibody, clone MIH3 (BioLegend, USA). Primary endpoint was the correlation between the CTCs PD-L1 expression and overall survival (OS). Among secondary objectives, we evaluated the correlation between PD-L1 expression on CTCs and matched tumor tissue and the correlation of CTC number and baseline tumor size (BTS). RESULTS: Thirty-nine patients treated with anti-PD-1/PD-L1 agents as second- or third-line therapy were enrolled. Patients were divided into 3 groups: no CTC detectable (CTCnull, n = 15), PD-L1 positive CTC (CTCpos, n = 13), and PD-L1 negative CTC (CTCneg, n = 11). Median OS in patients with CTCneg was 2.2 months, 95% confidence interval (CI), 0.8-3.6 (reference) versus 3.7 months, 95% CI, 0.1-7.5 (hazard ratio [HR] 0.33; 95% CI, 0.13-0.83; P = .019) in patients with CTCpos versus 16.0 months, 95% CI, 2.2-29.8 (HR 0.17; 95% CI, 0.06-0.45; P< .001) in patients with CTCnull. No correlation was found between PD-L1 expression on CTCs and on tumor tissue. CTC number was correlated with BTS. CONCLUSION: PD-L1 expression on CTCs is a promising biomarker in patients with NSCLC treated with ICIs. Further validation as predictive biomarker is needed.