Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors In Patients Research Articles

Patients with EGFR mutant (m) MET-altered NSCLC receiving tepotinib with an EGFR tyrosine kinase inhibitor (TKI): A case series.

9070 Background: Oncogenic activation of MET is a common mechanism of acquired resistance to EGFR TKIs in patients (pts) with EGFRm NSCLC, with MET amplification (amp) constituting the most frequent cause of bypass pathway activation. Currently, there are no approved targeted treatment options for these pts. Data from the Phase II INSIGHT (NCT01982955) and INSIGHT 2 (NCT03940703) studies indicate the combination of the selective MET TKI tepotinib plus an EGFR TKI has encouraging activity. We present a case series of pts with EGFRm MET-altered NSCLC receiving tepotinib plus an EGFR TKI outside of clinical trials. Methods: Access to tepotinib was provided to pts with EGFRm MET-altered NSCLC and resistance to EGFR TKIs through unsolicited compassionate use requests. All pts received tepotinib (500 mg [450 mg active moiety] once daily; first dose by Oct 2022) plus an EGFR TKI. Participating physicians provided case information up to January 2023. Results: 28 cases of pts with EGFRm NSCLC and MET alterations who received tepotinib plus an EGFR TKI were collated. 21 pts had METamp after EGFR TKI treatment, 5 had MET overexpression, and 2 had MET exon 14 skipping. Pts were aged 41–86 years, 15 were Asian, 13 were white, 19 were female, 8 had smoking history, and all had adenocarcinoma histology. METamp was detected by tissue biopsy in 17 pts, and liquid biopsy in 4 pts. Of 12 pts with METamp detected by FISH, gene copy number ranged from 5.3–33.4, and MET:CEP7 ratio from 0.7–15.1. EGFR TKIs received in combination with tepotinib were osimertinib (n = 21, 19 of whom received prior osimertinib), gefitinib (n = 6), dacomitinib (n = 1), afatinib (n = 1), with 1 pt received gefitinib followed by osimertinib. Tepotinib plus EGFR TKI was received by 9 pts as second-line, 9 as third-line, and 10 as fourth-or-later line. Median treatment duration was 8.8 months (range 1.3–20.6), with treatment ongoing in 13 pts (10 with current duration ≥10 months). Per the physician’s assessment, 25/28 pts (89%) had clinical benefit, 16 of whom (57%) were considered to have a partial response (PR). Clinical benefit was reported in 18/21 (86%) pts with METamp (12 PR, 57%), in 5/5 with MET overexpression (2 PR), and 2/2 with MET exon 14 skipping (2 PR). The most reported adverse event (AE) considered related to tepotinib was edema in 15 pts (most commonly peripheral edema). Grade 3 AEs related to tepotinib were reported in 5 pts (including Grade 3 edema in 2 pts), 1 of whom discontinued the combination due to Grade 3 pneumonitis. Conclusions: Tepotinib plus an EGFR TKI showed promising clinical activity in pts with MET-altered NSCLC who have progressed on a previous EGFR TKI, including those with several lines of prior treatment. Clinical benefit was observed irrespective of MET alteration type in this case series of pts treated outside of clinical trials, with a large proportion of patients continuing to benefit from ongoing treatment.

Concurrent EGFR wild-type tongue squamous cell carcinoma and EGFR-mutant lung adenocarcinoma and response to osimertinib.

e18074 Background: Epidermal growth factor receptor (EGFR) mutation is most commonly oncogenic driver in lung adenocarcinoma with 50% incidence in Asians.Osimertinib is the third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), which has been widely used in metastatic EGFR-mutant non-small cell lung cancer (NSCLC) and has significantly improved outcomes. At present, the treatment of HNSCC mainly relies on surgery or chemoradiotherapy. EGFR is overexpressed in more than 90% of head and neck squamous cell carcinoma (HNSCC). Targeted therapy for HNSCC is mainly monoclonal antibodies, while the application of small molecule inhibitors is limited. The EGFR-TKI can only be applied in subsequent-line, when disease progression on or after platinum therapy. However, the efficacy of EGFR-TKI in patients with both NSCLC and HNSCC remains unclear. Methods: We searched all patients with EGFR-mutation metastatic non-small cell lung cancer and HNSCC who used EGFR-TKI in the Second Xiangya Hospital. Tumor sections were assessed immunohistochemically using PD-L1 and EGFR expression. EGFR amplification was detected by fluorescence in situ hybridization (FISH). We collected clinical characteristics and treatment histories for all patients including time to progression on EGFR-TKI. Time to progression on EGFR-TKI was defined as time from start of EGFR-TKI to time of radiographic RECIST progression. The efficacy and prognosis were evaluated based on the RECIST (version 1.1). Results: We found an advanced lung adenocarcinoma patient who harbored an EGFR-mutation and concurrently had tongue squamous cell carcinoma with EGFR wild-type.The tongue tumor tissue sample for EGFR expression was positive by immunohistochemistry and EGFR amplification was negative by FISH. NGS showed inactive mutation of patched1 (PTCH1) and EGFR wild-type.PET-CT scans demonstrated a partial response (PR) of the lung tumor and tongue cancer after two months of treatment of osimertinib. The lung tumor maintian partial response until now (nearly 30 months). And the tongue tumor reached the first progression- free survival (PFS) at 21 months. Conclusions: The patient with NSCLC and tongue cancer who exhibited objective response to EGFR-TKI, osimertinib monotherapy. The result indicates a clear response of tongue cancer to osimertinib and the potential for the use of osimertinib in tongue cancer. However, with the specific mechanism largely unknown, it is necessary to study further the effect of osimertinib on HNSCC.

Inhibition of PLK1 Destabilizes EGFR and Sensitizes EGFR-Mutated Lung Cancer Cells to Small Molecule Inhibitor Osimertinib.

Tyrosine kinase inhibitors (TKI) targeting the epidermal growth factor receptor (EGFR) have significantly prolonged survival in EGFR-mutant non-small cell lung cancer patients. However, the development of resistance mechanisms prohibits the curative potential of EGFR TKIs. Combination therapies emerge as a valuable approach to preventing or delaying disease progression. Here, we investigated the combined inhibition of polo-like kinase 1 (PLK1) and EGFR in TKI-sensitive EGFR-mutant NSCLC cells. The pharmacological inhibition of PLK1 destabilized EGFR levels and sensitized NSCLC cells to Osimertinib through induction of apoptosis. In addition, we found that c-Cbl, a ubiquitin ligase of EGFR, is a direct phosphorylation target of PLK1 and PLK1 impacts the stability of c-Cbl in a kinase-dependent manner. In conclusion, we describe a novel interaction between mutant EGFR and PLK1 that may be exploited in the clinic. Co-targeting PLK1 and EGFR may improve and prolong the clinical response to EGFR TKI in patients with an EGFR-mutated NSCLC.

Making the Best Use of Available Weapons for the Inevitable Rivalry-Resistance to EGFR-TKIs

The emergence of epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) revolutionized the treatment of advanced-stage non-small cell lung cancer (NSCLC). Detected in more than 50% of late-stage lung adenocarcinoma in Asian patients, the EGFR mutation was regarded as a golden mutation for Asians. However, resistance to TKIs seems inevitable and severely hinders patients from getting further benefits from treatment. Even though resistance caused by EGFR T790M could be effectively managed by third-generation EGFR-TKIs currently, resistance to third-generation EGFR-TKIs is still a troublesome issue faced by both clinicians and patients. Various efforts have been made to maximize the benefits of patients from EGFR-TKIs therapy. Thus, new requirements and challenges have been posed to clinicians of this era. In this review, we summarized the clinical evidence on the efficacy of third-generation EGFR-TKIs in patients with EGFR-mutated NSCLC. Then, we discussed advancements in sequential treatment aiming to delay the onset of resistance. Moreover, the resistance mechanisms and features were depicted to help us better understand our enemies. Lastly, we put forward future strategies, including recent approaches involving the utilization of antibody drug conjugates against resistance and research directions about shaping the evolution of NSCLC as a core idea in the management of NSCLC.

A Real-world Study on the Expression Characteristics of PD-L1 in Patients with Advanced EGFR Positive NSCLC and Its Relationship with the Therapeutic Efficacy of EGFR-TKIs

Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) is the first choice for first-line treatment of advanced patients with EGFR positive non-small cell lung cancer (NSCLC). For advanced NSCLC patients with negative drive gene and positive programmed cell death ligand 1 (PD-L1) or highly expressed NSCLC patients, the first-line treatment recommends immune checkpoint inhibitors (ICIs) monotherapy or ICIs combined chemotherapy. Therefore, the first-line treatment strategy for advanced NSCLC patients with EGFR positive at different PD-L1 expression levels is worth further exploring. Many previous studies have suggested that the expression of PD-L1 is obviously affected by EGFR mutation, and the expression of PD-L1 is likely to be related to the mechanism of EGFR-TKIs resistance. The purpose of this study was to analyze the expression characteristics of PD-L1 in patients with advanced EGFR positive NSCLC and its relationship with the efficacy of EGFR-TKIs. 159 patients with newly diagnosed advanced NSCLC with EGFR positive (including 141 patients with EGFR sensitive mutations) were enrolled to analyze the relationship between clinicopathological characteristics and PD-L1 expression. The factors affecting the therapeutic effect of EGFR-TKIs in 141 patients with EGFR sensitive mutations were also explored. The PD-L1 expression of the included patients was classified according to the tumor promotion score (TPS): negative (TPS<1%) accounted for 47.2%, low expression (1%≤TPS<50%) accounted for 32.1%, and high expression (TPS≥50%) accounted for 20.7%. Among them, patients with solid predominant cancer cell pathomorphology classification are more likely to have high expression of PD-L1, accounting for 52.9% (P<0.0001). The median progression-free survival (mPFS) of patients with PD-L1 negative expression, low expression and high expression who received first generation EGFR-TKIs treatment were 12.4 months, 10.5 months and 3.7 months, respectively, with significant statistical difference (P<0.0001). During the EGFR-TKIs treatment, patients with a history of radiotherapy for lung lesions have a longer PFS benefit than those without a history of radiotherapy (mPFS: 17.0 months vs 9.3 months, P<0.0001). The expression level of PD-L1 in advanced EGFR positive NSCLC patients was significantly correlated with the pathomorphology classification of cancer cells. The efficacy of EGFR-TKIs in patients with PD-L1 overexpression NSCLC was significantly poor. PFS can be significantly prolonged during targeted therapy combined with radiotherapy of lung lesions.

Survival Outcomes of Calcium Channel Blocker Therapy in Patients With Non-Small Cell Lung Cancer Treated With Epidermal Growth Factor Receptor Inhibitors: A Retrospective Study.

Non-cancer drugs are currently being repurposed for cancer treatment. Mounting evidence highlights the influence of calcium channels on tumorigenesis and progression. Hence, inhibition of calcium signaling may be a promising cancer treatment strategy. In this study, we aimed to examine whether calcium channel blockers (CCBs) affect the efficacy of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) in patients with non-small cell lung cancer (NSCLC). We conducted a retrospective analysis. In this study, conducted between January 2009 and June 2021, patients with NSCLC treated with erlotinib, or gefitinib for at least 1 week were enrolled and divided into 2 groups: CCBs-/EGFR-TKIs+ and CCBs+/EGFR-TKIs+, depending on whether they received CCB therapy. Progression-free survival (PFS) and overall survival (OS) were determined as the primary and secondary endpoints, respectively. : The estimated median PFS and OS for the CCBs-/EGFR-TKIs+group were 7.70 and 12.17 months, respectively, and they were significantly different from those of the CCBs+/EGFR-TKIs+ group (10.43 and 18.07 months, respectively). CCB use was associated with improved PFS (adjusted hazard ratios [HR] 0.77, 95% confidence interval [CI]: 0.61-0.98; P = .035) and OS (adjusted HR 0.66, 95% CI: 0.51-0.84; P < .001). Calcium channels have been implicated in cancer pathogenesis. Our findings revealed the potential additive anticancer effects of CCBs when used concomitantly with EGFR-TKIs. However, study limitations, including the retrospective nature and small number of patients, necessitate large-scale prospective studies on the therapeutic potential of CCB as an adjunctive therapy with EGFR-TKIs in patients with NSCLC.

EGFR exon 20 insertion variants A763_Y764insFQEA and D770delinsGY confer favorable sensitivity to currently approved EGFR-specific tyrosine kinase inhibitors

Background: The EGFR exon 20 insertions (ex20ins) D770_N771insSVD and V769_D770insASV are most frequent in non-small-cell lung cancer (NSCLC) and are associated with intrinsic resistance to currently approved EGFR tyrosine kinase inhibitors (TKIs). A763_Y764insFQEA and D770delinsGY, respectively, account for 3%-8% and 2.0%-4.8% of EGFR ex20ins in NSCLC and are associated with a more favorable response to EGFR-specific TKIs as per case reports. The aim of this study was to elucidate the molecular structures of these mutants and their binding affinities to diverse EGFR TKIs and compare the clinical outcomes in NSCLC patients harboring these mutations. Methods: A real-world cohort study was conducted to evaluate and compare the clinical outcomes of EGFR TKIs among NSCLC patients with different EGFR ex20ins mutants in response to EGFR TKIs. The structures of A763_Y764insFQEA and D770delinsGY were also analyzed and drug binding simulations were performed. Results: With a median follow-up of 24.0months, the first-line objective response rate (ORR), disease control rate (DCR), and median progression-free survival (PFS) were, respectively, 0 (0/16), 50.0% (8/16), and 2.07months (95%CI, 0-6.25) in patients harboring D770_N771insSVD and V769_D770insASV variants and 33.3% (4/12), 83.3% (10/12), and 9.97months (95%CI, 4.75-15.19) in patients with A763_Y764insFQEA and D770delinsGY variants. There was a significant difference between the PFS of these two subgroups (median, 9.97 vs.2.07months, HR = 0.33, 95%CI, 0.13-0.85, p = 0.02). Similarly, the PFS was significantly longer after second-line treatment with EGFR TKIs in patients harboring A763_Y764insFQEA and D770delinsGY compared to those with other insertions (median, 6.77 vs.2.23months, HR = 0.14, p < 0.001). Computational simulations indicated that A763_Y764insFQEA and D770delinsGY mutants were structurally similar to wild-type EGFR. In contrast, the C-helix and phosphate-binding loop of D770_N771insSVD and V769_D770insASV had shifted into the drug-binding pocket, resulting in significant steric hindrance and a lack of affinity for the currently approved EGFR inhibitors. Conclusion: NSCLC patients harboring A763_Y764insFQEA and D770delinsGY insertions of EGFR are responsive to the currently approved EGFR TKIs as opposed to patients with the D770_N771insSVD and V769_D770insASV variants. Therefore, A763_Y764insFQEA and D770delinsGY should be classified as active mutations among heterogeneous EGFR ex20ins subtypes and the carriers can be treated with the suitable EGFR TKIs.

Efficacy of epidermal growth factor receptor tyrosine kinase inhibitors in patients with recurrent non-small cell lung cancer after definitive concurrent chemoradiation or radiotherapy.

Whether prior radiotherapy (RT) affects the response of EGFR-mutated non-small cell lung cancer (NSCLC) to EGFR tyrosine kinase inhibitor (TKI) remains elusive. Patients with EGFR-mutated NSCLC treated with EGFR TKIs who recurred after curative treatment at Asan Medical Center, Seoul, Korea were included. The progression-free survival (PFS) and overall survival (OS) from the initiation of EGFR TKI in patients who recurred after definitive RT were analyzed and compared to the outcomes of RT-naïve patients with advanced NSCLC treated with EGFR TKIs from previously reported prospective clinical trial results. A total of 60 patients who recurred after definitive RT were included. The median age was 70years (range, 38-88), with 24 patients (40.0%) being males. Among the 60 patients, 52 patients (86.7%) had exon 19 deletion or L858R mutation, with 49 patients (81.7%) receiving gefitinib as the first-line EGFR TKI. The median PFS and OS from the initiation of EGFR TKI were 10.4months (95% confidence interval [CI], 7.4-13.2) and 21.3months (95% CI, 13.4-28.8), respectively. The EGFR TKI efficacy in EGFR-mutated patients with NSCLC who recurred after RT was comparable with that in historic controls of RT-naïve patients with advanced NSCLC treated with EGFR TKIs, indicating that RT may not affect EGFR TKI efficacy.

Association of Tumor PD-L1 Expression With Time on Treatment Using EGFR-TKIs in Patients With EGFR-Mutant Non-small Cell Lung Cancer.

The association between tumor PD-L1 expression and the rate of acquisition of the T790M mutation during treatment with first-/second-generation epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) is a matter of study. This retrospective study was conducted to evaluate the association of tumor PD-L1 expression with the time on treatment under EGFR-TKIs in patients with EGFR-mutant non-small cell lung cancer (NSCLC), treated with first-/second-generation EGFR-TKIs. We conducted a retrospective review of the medical charts of patients with EGFR-mutant NSCLC treated with first- /second-generation EGFR-TKIs. Time on treatment with EGFR-TKIs was defined as the sum of progression-free survival period (PFS) from the start of treatment with first- /second-generation EGFR-TKIs and the PFS from the start of osimertinib treatment after acquisition of the T790M mutation. Tumor PD-L1 expression was evaluated using the 22C3 antibody. Data of a total of 49 patients were analyzed, including 20 patients with negative tumor PD-L1 expression (tumor proportion score <1%) and 29 patients with positive tumor PD-L1 expression (tumor proportion score ≥1%). In the negative tumor PD-L1 expression group, the T790M mutation was detected in 12 (75%) of the 16 patients. In the positive tumor PD-L1 expression group, the T790M mutation was detected 6 (31.6%) out of the 19 patients in whom it was tested. The median (95% confidence interval) time on treatment with EGFR-TKIs was 21.7 (12.9-24.8) months and 12.3 (5.6-22.2) months in the negative and positive tumor PD-L1 expression groups, respectively. Analysis using a Cox proportional hazards model identified performance status and presence/absence of tumor PD-L1 expression as significantly associated with the time on treatment with EGFR-TKIs. EGFR-mutant NSCLC patients with negative tumor PD-L1 expression showed a higher rate of acquisition of the T790M mutation and implementation rate of osimertinib therapy, leading to a longer time on treatment with EGFR-TKI.

Osimertinib: A Review in Previously Untreated, EGFR Mutation-Positive, Advanced NSCLC.

Activating mutations in the epidermal growth factor receptor (EGFR) gene have been identified as key oncogenic drivers of non-small cell lung cancer (NSCLC). Osimertinib (Tagrisso®) is an orally administered, third-generation EGFR tyrosine kinase inhibitor (EGFR-TKI) that is widely approved for the first-line treatment of advanced NSCLC with activating EGFR mutations. In the pivotal phase III FLAURA trial, osimertinib significantly prolonged progression-free survival (PFS) and overall survival (OS) relative to first-generation EGFR-TKIs in patients with previously untreated, EGFR mutation-positive, advanced NSCLC. Osimertinib also significantly prolonged central nervous system (CNS) PFS in patients with CNS metastases at trial entry. Osimertinib had a generally manageable tolerability profile; the majority of adverse events considered to be possibly related to treatment were of mild to moderate severity. Osimertinib represents a valuable targeted therapeutic for use in adults with previously untreated, EGFR mutation-positive, advanced NSCLC.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11523-021-00839-w.

Rechallenge with previously administered epidermal growth factor receptor-tyrosine kinase inhibitors in EGFR-mutated non-small cell lung cancer with leptomeningeal metastasis.

Objectives In EGFR-mutated non-small cell lung cancer (NSCLC) patients, approximately 80-90% of leptomeningeal metastasis (LM) develops after failed initial treatment with epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (EGFR-TKI). However, the efficacy of rechallenging with previously administered EGFR-TKIs in patients with EGFR-mutated NSCLC and the LM that develops following EGFR-TKI treatment failure remains unknown. Materials and methods We retrospectively reviewed medical records of patients with EGFR-mutated NSCLC and LM, from November 2011 to August 2019. The patients were classified according to the LM treatment type: switched to previously unadministered EGFR-TKIs (Switch-TKI) or rechallenge with previously administered EGFR-TKIs (Rechallenge-TKI). Results In total, 50 patients treated with EGFR-TKI after LM diagnosis were included; 35 were treated with Switch-TKI and 15 with Rechallenge-TKI. The median overall survival (OS) from the time of LM diagnosis was 6.2months in all study patients. According to the treatment type, the median OS from the time of LM diagnosis was 6.9months in Switch-TKI patients and 4.9months in Rechallenge-TKI patients. There was no significant difference in the OS between the Switch-TKI and Rechallenge-TKI groups (P = 0.864). Thirty-five patients were treated with erlotinib and 15 with osimertinib; Regardless of the type for EGFR-TKI, there was no significant difference in OS between patients treated with Switch-TKI and those treated with Rechallenge-TKI. Conclusion Rechallenge of previously administered EGFR-TKIs may be a therapeutic option for LM development after EGFR-TKI treatment failure in patients with EGFR-mutated NSCLC, not only switching to previously unadministered EGFR-TKIs.

Acquired Resistance to Third-Generation EGFR Tyrosine Kinase Inhibitors in Patients With De Novo EGFRT790M-Mutant NSCLC

IntroductionEGFRT790M mostly exists subclonally and is acquired as the most common mechanism of resistance to EGFR tyrosine kinase inhibitors (TKIs). Nevertheless, because de novo EGFRT790M-mutant NSCLC is rare, little is known on acquired resistance mechanisms to third-generation EGFR TKIs. MethodsAcquired resistance mechanisms were analyzed using tumor and plasma samples before and after third-generation EGFR TKI treatment in four patients with de novo EGFRT790M-mutant NSCLC. Genetic alterations were analyzed by whole-exome sequencing, targeted sequencing, fluorescence in situ hybridization, and droplet digital PCR. MTORL1433S, confirmed for oncogenicity using the Ba/F3 system, was reproduced in H1975 cell lines using CRISPR/Cas9-RNP. ResultsOf seven patients with NSCLC with de novo EGFRT790M/L858R mutation, four (LC1–4) who received third-generation EGFR TKIs acquired resistance after achieving a partial response (median = 27 mo, range: 17–48 mo). Novel MTORL1433S and EGFRC797S/L798I mutations in cis, MET amplification, and EGFRC797S mutation were identified as acquired resistance mechanisms to third-generation EGFR TKIs. The MTORL1433S mutation was oncogenic in Ba/F3 models and revealed resistance to osimertinib through AKT signaling activation in NCI-H1975 cells harboring the MTORL1433S mutation edited by CRISPR/Cas9 (half-maximal inhibitory concentration, 800 ± 67 nM). Osimertinib in combination with mTOR inhibitors abrogated acquired resistance to osimertinib. ConclusionsActivation of bypass pathways and the EGFRC797S or EGFRC797S/L798I mutation were identified as acquired resistance mechanisms to third-generation EGFR TKIs in patients with NSCLC with de novo EGFRT790M mutation. In addition, MTORL1433S- and EGFRL858R/T790M-mutant NSCLC cells were sensitive to osimertinib plus mTOR inhibitors.

EGFR Exon 20 Insertion Mutations: Clinicopathological Characteristics and Treatment Outcomes in Advanced Non–Small Cell Lung Cancer

BackgroundEpidermal growth factor receptor gene (EGFR) exon 20 insertion (ex20-ins) mutations are an uncommon and heterogeneous group of non–small cell lung cancers (NSCLCs), resistant to conventional EGFR tyrosine kinase inhibitors (TKIs). Characteristics and outcomes of patients with EGFR ex20-ins have not been fully established; we sought to clarify them using a multinational patient database. Patients and MethodsPatients with NSCLC from six Australian institutions with EGFR exon 20 mutations (ex20-mut), excluding T790M, were retrospectively reviewed. Clinical characteristics and outcomes with systemic treatments were collected and analyzed using comparative statistics. ResultsAmong 109 patients with ex20-mut, 61% were females and 75% were Caucasians. More males presented with de novo metastatic disease (84% vs. 51%; P = .002). Central nervous system (48%) and liver (24%) metastases were common within metastatic patients (n = 86). Thirty-nine patients received platinum-based chemotherapy (PBC) and achieved a 43% objective response rate (ORR), median progression-free survival (mPFS) of 6.9 months, and median overall survival (mOS) of 31.0 months. Twenty-three of the patients with ex20-ins received conventional TKIs, resulting in an ORR of 13%, mPFS of 3.4 months (95% confidence interval [CI], 1.91-6.25), and mOS of 31.0 months (95% CI, 15.09-not reached). Nine patients with S786I mutations received TKIs, resulting in an ORR of 50%, mPFS of 18.2 months (2.79-not reached), and mOS of 33.4 months (95% CI, 16.14-not reached). Twenty-three patients received immune checkpoint inhibitor monotherapy (ICIm), resulting in an ORR of 4%, mPFS of 2.6 months (95% CI, 1.91-4.83), and mOS of 30.8 months (95% CI, 17.62-41.62). ConclusionAlthough phenotypically similar to patients with common EGFR mutations, patients with EGFR ex20-mut had worse survival, perhaps due to the lack of targeted therapies. Chemotherapy was superior to conventional EGFR TKIs in patients with EGFR ex20-ins, although there was moderate activity of TKIs in S768I mutations. ICIm was ineffective.

Adenocarcinoma of High-Grade Patterns Associated with Distinct Outcome of First-Line Chemotherapy or EGFR-TKIs in Patients of Relapsed Lung Cancer.

PurposeHigh-grade patterns (micropapillary/solid/complex gland) are associated with a higher recurrence rate and shorter disease-free survival. Thus far, it remains unclear whether the efficacy of first-line anticancer therapy is different from that of the other adenocarcinoma subgroups for patients with high-grade patterns. The study aimed to investigate the association between an adenocarcinoma with high-grade patterns with the outcomes of first-line treatment in patients with lung cancer.Patients and MethodsPatients with a high-grade pattern adenocarcinoma (more than 20% of micropapillary/solid components/complex glandular patterns) were retrospectively analyzed between June 2015 and June 2017. Patients’ clinical characteristics and treatment outcomes were compared with those of the remaining control adenocarcinoma subgroups.ResultsIn total, 239 patients with adenocarcinoma, including 115 (48.1%) high-grade patterns and 124 (51.9%) control groups, were enrolled. Patients’ clinical characteristics such as age, sex, smoking status, and stage were similar between the two groups. Among them, 108 patients received first-line chemotherapy, and 131 received epidermal growth factor receptor–tyrosine kinase inhibitors (EGFR-TKIs). In the chemotherapy group, adenocarcinoma of high-grade patterns had a significantly lower objective response rate (ORR; 15.6% vs 36.4%, P=0.045), shorter progression-free survival (PFS; median 4.1 vs 5.4 months, P=0.007) and overall survival (OS, median 19.6 vs 23.8 months, P=0.048) compared with the control group. As for these treated with EGFR-TKIs, a similar ORR (70.7% vs 72.1%, P=0.703), PFS (median 11.3 vs 13.9 months, P=0.065) and OS (median 34.1 vs 29.6%, p=0.575) were observed between these two groups.ConclusionAn adenocarcinoma with high-grade patterns is associated with inferior outcomes to first-line chemotherapy in relapsed lung cancer. Patients who received chemotherapy had a significantly shorter PFS and OS and lower ORR than control subjects, while there was no difference in the EGFR-TKI cohort. This study is the first to report the distribution of adenocarcinoma with high-grade patterns.

Molecular Characteristics and Clinical Outcomes of EGFR Exon 19 C-Helix Deletion in Non–Small Cell Lung Cancer and Response to EGFR TKIs

Epidermal growth factor receptor (EGFR) exon 19 deletion (E19del) is the most common activating mutation in advanced non–small cell lung cancer (NSCLC) and associates with the sensitivity of EGFR tyrosine kinase inhibitors (TKIs) treatment. However, not all mutant patterns of E19del have been well studied for the limited coverage of regular EGFR mutation testing. Here, we performed a retrospective cohort study of the C-helix E19del in advanced NSCLC patients based on the screening data by the next-generation sequencing (NGS) platform. From May 2012 to December 2019, clinical information and specimen from 7544 consecutive advanced (IIIB/IV) NSCLC patients were collected and screened for EGFR gene mutations by NGS from multicenters in China. The molecular characteristics and responsiveness to first-line EGFR TKIs therapy in NSCLC patients with C-helix E19del were analyzed. The clinical characteristics were also compared between patients with classical E19del and C-helix E19del. Thirty-eight (2.6%) patients with C-helix E19del and 1400 (97.4%) patients with classical E19dels were identified from 1438 patients with E19del. No significant difference in clinical characteristics was observed between the C-helix E19del and classical E19del groups (P > .05), except for histology (P < .001). All 22 patients with C-helix E19del as p.S752_I759del, p.A750_E758del, p.A750_E758delinsP, p.T751_A755delinsNY, p.T751_I759delinsG, p.T751_I759delinsLD, p.T751_I759delinsN, p.T751_L760delinsNL, and p.T751_D761delinsLY reached the best response as partial response rate (72.7%), and the progression-free survival (PFS) was 12.0 months. The PFS after EGFR TKIs in patients with C-helix E19del tended to be longer than patients with classical E19del but has no statistical significance (12.0 months vs 8.5 months, P = .06). The C-helix E19del could be a positive biomarker for predicting response to EGFR TKIs in advanced NSCLC patients. NGS should be the appropriate platform to identify this rare population, especially when patients harbor no actionable driver mutation initially and are reluctant to accept chemotherapy as first-line therapy.

Salvage Chemotherapy Following Osimertinib in Non-small Cell Lung Cancer Harboring Epidermal Growth Factor Receptor Mutation.

The current study reports the type of salvage chemotherapy following osimertinib and its treatment efficacy in patients with non-small-cell lung carcinoma (NSCLC) who acquire resistance to osimertinib. In this retrospective cohort study, data from the medical charts of 40 patients with NSCLC treated with osimertinib were obtained, primarily focusing on 14 undergoing salvage chemotherapy including epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) or cytotoxic agents immediately following osimertinib. The treatment efficacy of salvage chemotherapy was evaluated. Five and nine patients received EGFR-TKI and cytotoxic agents following osimertinib, respectively. The overall response rate to EGFR-TKI treatment following osimertinib tended to be lower than that for cytotoxic agents (0% vs. 44.4%). The median progression-free-survival was significantly poorer in patients receiving EGFR-TKI treatment than in those receiving cytotoxic agents. Cytotoxic agent administration should be considered more frequently than EGFR-TKIs for patients with NSCLC resistant to osimertinib.

Heregulin expression and its clinical implication for patients with EGFR-mutant non-small cell lung cancer treated with EGFR-tyrosine kinase inhibitors

Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) are standard therapy for EGFR-mutant non-small cell lung cancer (NSCLC). Preclinically, HER3 ligand heregulin induces resistance to EGFR-TKIs, whereas the pan-human EGFR family inhibitor afatinib remains effective. Here, we examined whether soluble heregulin levels have clinical implications for EGFR-mutant NSCLC treated with EGFR-TKIs. Soluble heregulin was immunologically measured in plasma from EGFR-mutant NSCLC patients. Cutoff values were determined by 1-year PFS ROC curve. The relationship between soluble heregulin and PFS following EGFR-TKI therapy was analyzed by Cox proportional hazards model. Seventy-three patients were enrolled: 44 were treated with 1st-generation and 29 with 2nd-generation EGFR-TKIs. Soluble heregulin levels varied (range: 274–7,138 pg/mL, median: 739 pg/mL). Among patients treated with 1st-generation EGFR-TKIs, those with high heregulin (n = 20, >800 pg/mL) had a tendency for shorter PFS than those with low heregulin (n = 24, <800 pg/mL), with median PFS of 322 and 671 days, respectively. Cox proportional hazards model also indicated a trend toward resistance against 1st-generation EGFR-TKIs (HR: 1.825, 95% CI: 0.865–4.318) but not against 2nd-generation EGFR-TKIs. Soluble heregulin potentially correlates with resistance to EGFR-TKIs but not 2nd-generation EGFR-TKIs in patients with EGFR-mutant NSCLC.

492P - Feasibility of rebiopsy and sequential treatment of EGFR tyrosine kinase inhibitors in real world patients with EGFR mutant non-small cell lung cancer

BackgroundThe third generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) osimertinib is a standard treatment in case of T790M mutation positive after failure to first or second generation EGFR TKI in patients with EGFR-mutant non-small cell lung cancer (NSCLC). We investigated a success rate of rebiopsy and sequential EGFR TKI treatment in real world setting in Korea. MethodsWe retrospectively reviewed medical records of patients with EGFR mutant advanced NSCLC who received first- or second- generation EGFR TKI between Jan 2012 and Jun 2018 at a single center in Korea. ResultsAmong 221 patients with EGFR-mutant NSCLC, 68 patients who were lost to follow up (n = 19) or still on 1st- or 2nd- generation TKI (n = 49) at time of analysis were excluded. Forty-three out of remaining 153 patients (28%) did not have a chance of consideration for second line treatment because of deterioration of performance status (n = 21) or death (n = 22), especially in elderly over 70 years. Tests for acquired EGFR mutation were performed in 76% (84/110), among which 73 cases were tissue rebiopsy and 11 cases were plasma EGFR mutation analysis. Acquisition of tumor tissue in rebiopsy was successful in 93% (68/73). The most common reason of not doing rebiopsy was lack of sequential treatment options (n = 24). Ten patients with negative T790M or failure at initial rebiopsy underwent more than two times of repeated EGFR mutation analysis, among which four patients had eventually positive T790M at some point of disease course. Overall T790M positive rate was 54% (45/84). Among 7 patients with initially negative T790M mutation in plasma analysis, further rebiopsy from tumor tissue was performed only in one patients because of patient's refusal (n = 2), physician's decision to continue post-progression EGFR TKI (n = 2), poor performance status (n = 1), and unaccessibility to tumor tissue (n = 1). ConclusionsAbout 30% of patients with EGFR mutant NSCLC did not have a chance of consideration for second line EGFR TKI treatment, especially in elderly over 70 years. Success rate of tumor tissue rebiopsy was over 90% in real world setting, and repeated rebiopsy may increase detection rate of acquired T790M mutation. Legal entity responsible for the studyThe authors. FundingHas not received any funding. DisclosureAll authors have declared no conflicts of interest.

Third-generation epidermal growth factor receptor tyrosine kinase inhibitors for the treatment of non-small cell lung cancer.

Mutations in the epidermal growth factor receptor (EGFR) gene are the most common targetable genomic drivers of non-small cell lung cancer (NSCLC), occurring in approximately 50% and 10-15% of adenocarcinomas of the lung in Asian and Western populations, respectively. The most common EGFR-activating mutations, the exon 19 deletion and the L858R point mutation occurring in the receptor tyrosine kinase domain, are susceptible to inhibition. The first EGFR tyrosine kinase inhibitors (TKIs) to be evaluated were the reversible first-generation EGFR TKIs, gefitinib and erlotinib, followed by the irreversible second-generation EGFR TKIs, afatinib and dacomitinib. The study of acquired resistance mechanisms to first- and second-generation EGFR TKIs in patients with activating EGFR-mutated NSCLC identified the gatekeeper T790M point mutation, present in over 50% of cases, as the most common mechanism of acquired resistance. The need to overcome this resistance mechanism led to the development of third-generation EGFR TKIs, of which osimertinib is the only one to date with regulatory approval. In this review, we present the clinical context leading to the development of third-generation EGFR TKIs, the mode of action of these inhibitors and the clinical data supporting their use. We review third-generation TKI agents that are approved, in development, and those that failed in clinical trials. Finally, we will touch upon ongoing studies and future directions, such as combination treatment strategies, currently being explored to improve the efficacy of treatment with third-generation EGFR TKIs.

502P - Epidermal growth factor receptor tyrosine kinase inhibitor treatment response in advanced non-small cell lung cancer with uncommon mutations: A multicenter observational study

BackgroundTreatment with epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) is the standard therapy for advanced non-small cell lung cancer (NSCLC) with common EGFR mutations. However, the efficacy of EGFR-TKIs in patients with uncommon EGFR mutations remains unclear. MethodsWe retrospectively surveyed a consecutive database of patients with NSCLC with EGFR mutations. We analyzed the data of patients with NSCLC with uncommon mutations, including single or compound mutations, who were treated with EGFR-TKIs between May 2016 and October 2018. ResultsData from 543 patients were collected from five institutions, among whom 23 had EGFR uncommon mutations. Twenty-one patients who were treated with any EGFR-TKIs were analyzed in this study, 18 of whom were treated with EGFR-TKIs as first-line therapy (gefitinib 5, erlotinib 3, afatinib 10 patients). In contrast, three patients underwent cytotoxic chemotherapy as first-line therapy and were treated with EGFR-TKIs as second- and third-line therapy (gefitinib 1, erlotinib 1, afatinib 1 patient). According to the Response Evaluation Criteria in Solid Tumors, the overall response rate was 56%, and the disease control rate was 78%. The median progression-free survival (PFS) was 14.0 months in all patients with uncommon mutations. The median PFS of patients who were treated with first and second generation EGFR-TKIs were 14.0 months (n = 10) and 7.3 months (n = 11), respectively. Moreover, the PFS of patients with the G719X mutation (n = 12, median PFS: 32.9 months) was longer than that of patients with the L861Q mutation (n = 4, median PFS: 11.1) and compound mutations (n = 4, median PFS 7.3 months). ConclusionsFirst and second generation EGFR-TKIs are effective treatments for patients with NSCLC with uncommon mutations. Notably, a greater favorable response was observed in patients with G719X mutations than those with L861Q and compound mutations. Clinical trial identificationUMIN000028989. Legal entity responsible for the studyFumio Imamura. FundingAstraZeneca. DisclosureF. Imamura: Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): AstraZeneca. All other authors have declared no conflicts of interest.