Epidermal Growth Factor Receptor T790M-positive Non-small Cell Lung Cancer Research Articles

Predictive significance of circulating tumor DNA against patients with T790M-positive EGFR-mutant NSCLC receiving osimertinib

Circulating tumor DNA (ctDNA) provides molecular information on tumor heterogeneity. The prognostic usefulness of ctDNA after first-line epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are limited. Therefore, the present study evaluated ctDNA during osimertinib administration as a second-line or more setting to identify the relationship between EGFR mutation levels and outcomes in patients with advanced non-small cell lung cancer (NSCLC). Forty patients with EGFR T790M-positive NSCLC receiving osimertinib after prior EGFR-TKI treatment were registered. Plasma samples were collected at osimertinib pretreatment, after 1 month of treatment, and at the time of progressive disease (PD). ctDNA analysis was performed by digital polymerase chain reaction. The detection rate of copy numbers of exon 19 deletion, L858R, and T790M in plasma samples was significantly lower 1 month after osimertinib than at pretreatment, and significantly higher at PD than at 1 month, whereas that of C797S was significantly higher at PD than at 1 month. No statistically significant difference was observed in the copy numbers of exon 19 deletion, L858R, T790M, and C797S between complete response or partial response and stable disease or PD. The detection of T790M at PD after osimertinib initiation was a significant independent prognostic factor for predicting shorter prognosis, and the presence of major EGFR mutations at pretreatment and PD was closely linked to worse survival after osimertinib initiation. Molecular testing based on ctDNA is helpful for predicting outcomes of osimertinib treatment in T790M-positive NSCLC after previous EGFR-TKI treatment.

Real-world evidence of osimertinib in Chinese patients with EGFR T790M-positive non-small cell lung cancer: a subgroup analysis from ASTRIS study

PurposeASTRIS study aimed the largest to evaluate the effectiveness and safety of second- or higher-line osimertinib in patients with advanced/metastatic epidermal growth factor receptor (EGFR) T790M mutation-positive non–small cell lung cancer (NSCLC) in the real-world setting. Here we report the results of Chinese patients in ASTRIS study.MethodsAdults with EGFR T790M-positive advanced NSCLC pretreated with EGFR-tyrosine kinase inhibitor (EGFR-TKI), having a WHO performance status score of 0–2 and asymptomatic, stable central nervous system (CNS) metastases were included. All patients received once-daily osimertinib 80 mg orally. The outcomes included investigator-assessed clinical response, progression-free survival (PFS), time-to-treatment discontinuation (TTD), and safety.ResultsA total of 1350 patients were included. Response rate was 55.7% (95% confidence interval [CI] 0.53–0.58). The median PFS and the median TTD were 11.7 months (95% CI 11.1–12.5) and 13.9 months (95% CI 13.1–15.2), respectively. Overall, 389 patients (28.8%) had at least one protocol-specified adverse event (AE); AEs of interstitial lung diseases/pneumonitis-like events and QT prolongation were reported in 3 (0.2%) and 59 (4.4%) patients, respectively.ConclusionOsimertinib was effective in Chinese patients with T790M-positive NSCLC who had progressed after first- or second-generation EGFR-TKI in real-word setting and the results were consistent with ASTRIS study overall population and AURA studies. No new safety signals or events were identified.Clinical trial numberNCT02474355.

Clinical Outcomes of Patients with Epidermal Growth Factor Receptor–Mutated Non-Small-Cell Lung Cancer with Leptomeningeal Metastasis in the Modern Target Therapy Era

Leptomeningeal metastasis (LM) is a severe complication in patients with non-small-cell lung cancer (NSCLC) and the optimal treatment strategy remains a challenge. This study aimed to investigate the treatment strategies and clinical outcomes in these patients. We retrospectively reviewed the data of 44 patients with epidermal growth factor receptor (EGFR)-mutated NSCLC with LM between 2014 and 2020 at our institute. The patient characteristics, treatment approaches, LM progression-free survival (LMPFS) and overall survival (OS) after the diagnosis of LM (OSLM) were analyzed. The median OSLM was 16.0 months and the 3-year OS rate was 22.5%. The PFSLM in EGFR T790M-positive NSCLC patients with leptomeingeal disease was significantly improved by initiation of third-generation tyrosine kinase inhibitors (TKIs) compared with that of patients who were T790M negative (14.0 vs. 7.0 months; P= 0.030). A significantly higher LM disease control rate was shown in patients who received third-generation TKIs compared with previous generations of TKIs (90.1% vs. 60.0%; P= 0.024). Better Eastern Cooperative Oncology Group performance status, EGFR exon 19del, and clinical improvement of LM after therapy were independently associated with better OS. The survival of patients with NSCLC with LM has improved in the target therapy era. Our study provided real-world clinical evidence that patients with EGFR-mutated NSCLC who developed LM from previous TKIs can be benefit from third-generation EGFR-TKIs, especially for patients with EGFR T790M-positive.

Discovery of mobocertinib, a new irreversible tyrosine kinase inhibitor indicated for the treatment of non-small-cell lung cancer harboring EGFR exon 20 insertion mutations.

Epidermal growth factor receptor (EGFR) is essential for normal cellular functions. Mutations of EGFR’s kinase domain can cause dysregulation leading to non-small cell lung cancer (NSCLC). Exon 20 insertion (ex20ins) mutations in EGFR are one of the leading contributors to oncogenesis and confer insensitivity to most available therapeutics. Mobocertinib is a novel tyrosine kinase inhibitor (TKI) recently approved by the US FDA as a first-in-class small molecule therapeutic for EGFR ex20ins-positive NSCLC. When compared to osimertinib, a TKI indicated for the treatment of EGFR T790M-positive NSCLC, mobocertinib differs only by the presence of an additional C5-carboxylate isopropyl ester group on the middle pyrimidine core. Together with the acrylamide side chain that is responsible for irreversible inhibition, this additional C5-substituent affords mobocertinib high anticancer potency and specificity to EGFR ex20ins-positive lung cancer that is resistant to other EGFR TKIs. This review article provides an overview of the discovery of mobocertinib from osimertinib including their structure-activity relationships, mechanisms of action, preclinical pharmacology, pharmacokinetics, and clinical applications. The discovery and use of mobocertinib and other EGFR TKIs demonstrate the power of structure-based drug design and promising therapeutic outcomes of using precision medicine approaches in the management of molecularly defined tumors. Graphical abstract

Efficacy of osimertinib in epidermal growth factor receptor-mutated non-small-cell lung cancer patients with pleural effusion

BackgroundOsimertinib is a standard first-line treatment for advanced non-small-cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) mutations. Although malignant pleural effusion (PE) is a common clinical problem in NSCLC, information about the efficacy of osimertinib in patients with PE is limited, especially regarding its efficacy in EGFR T790M-negative patients with PE remains unclear.MethodsWe retrospectively reviewed the medical records of patients with NSCLC harboring EGFR mutations who were treated with osimertinib in our institution between May 2016 and December 2020.ResultsA total of 63 patients with EGFR mutated NSCLC were treated with osimertinib; 33 (12 with PE) had no EGFR T790M mutation, while 30 (12 with PE) had EGFR T790M mutation. In EGFR T790M-negative NSCLC, the progression-free survival (PFS) of the patients with PE was comparable to that of the patients without PE (median PFS 19.8 vs. 19.8 months, p = 0.693). In EGFR T790M- positive NSCLC, the PFS and overall survival (OS) of the patients with PE were significantly shorter than those of the patients without PE (median PFS 16.8 vs. 8.3 months, p = 0.003; median OS 44.9 vs. 14.2 months, p = 0.007). In the multivariate analysis, the presence of PE was independently associated with shorter PFS and OS in EGFR T790M-positive NSCLC patients, but not EGFR T790M-negative patients.ConclusionsThese data suggest the efficacy of osimertinib may differ between EGFR T790M-positive and -negative NSCLC patients with PE.

Furmonertinib: First Approval.

Furmonertinib mesylate (hereafter furmonertinib) [Ivesa®] is a selective epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) being developed by Allist Pharmaceuticals for the treatment of patients with EGFR mutation-positive non-small cell lung cancer (NSCLC). In March 2021, furmonertinib received its first approval in China for the treatment of patients with locally advanced or metastatic NSCLC with confirmed EGFR T790M mutation whose disease has progressed during or after EGFR TKI therapy. Furmonertinib (as monotherapy and/or combination therapy) continues to be assessed in phase I/II and phase III trials for NSCLC with EGFR mutation in China, and its clinical development is also underway/planned in China and elsewhere for NSCLC with various EGFR mutations. This article summarizes the milestones in the development of furmonertinib leading to this first approval for EGFR T790M-positive NSCLC.

The Allele Frequency of EGFR Mutations Predicts Survival in Advanced EGFR T790M-Positive Non-small Cell Lung Cancer Patients Treated with Osimertinib.

BackgroundThe allele frequency of epidermal growth factor receptor (EGFR) mutations could be a potential molecular biomarker for the outcome of osimertinib therapy.ObjectiveThe purpose of our study was to assess the clinical relevance of the allele frequency of EGFR mutations in plasma-based circulating tumor DNA (ctDNA) before starting osimertinib therapy in patients with advanced EGFR-mutated non-small cell lung cancer (NSCLC) who had progressed under treatment with EGFR tyrosine kinase inhibitors (TKIs).Patients and MethodsWe enrolled 141 patients with advanced EGFR T790M-positive NSCLC who underwent second-line osimertinib treatment. Plasma ctDNA was tested for EGFR-activating mutations (EGFR deletions in exon 19, L858R, L861Q, S768I) and T790M by means of droplet digital polymerase chain reaction (ddPCR).ResultsThe allele frequency of EGFR-activating mutations in plasma ctDNA before osimertinib initiation ranged from 0 to 81,543 copies/ml and was independently associated with progression-free survival (PFS) and overall survival (OS) after adjusting for known clinicopathological risk factors (PFS: adjusted hazard ratio [HR] 1.26, 95% confidence interval [CI] 1.15–1.39, P < 0.0001; OS: adjusted HR 1.32, 95% CI 1.18–1.47, P < 0.0001). The allele frequency of T790M in plasma ctDNA before starting osimertinib therapy ranged from 0 to 38,092 copies/ml. Multivariate analyses showed that a higher T790M allele frequency was associated with a trend towards a shorter PFS (adjusted HR 1.19, 95% CI 0.99–1.42, P = 0.05) and a significantly shorter OS (adjusted HR 1.25, 95% CI 1.02–1.53, P = 0.03) of the patients.ConclusionA higher allele frequency of EGFR mutations, particularly EGFR-activating mutations, in plasma ctDNA is a poor prognostic marker. Further studies on the clinical utility of liquid biopsy are needed.

PP229 Surrogate Outcomes In Health Technology Assessments Of Oncology Drugs: The Osimertinib Case

IntroductionDecision making in publicly funded healthcare systems must rely on patient-relevant outcomes that directly measure clinical benefit, such as overall survival and quality of life (QoL). However, studies that support market authorization of oncology drugs usually assess surrogate outcomes, without having previously demonstrated that these intermediate outcomes reliably predict clinical outcomes. As part of an HTA process, we evaluated the clinical benefit of osimertinib, compared with platinum-pemetrexed combination chemotherapy, in patients with epidermal growth factor receptor (EGFR) T790M mutation-positive advanced non-small cell lung cancer (NSCLC) that has progressed after first-line EGFR tyrosine kinase inhibitor (TKI) therapy.MethodsWe conducted a systematic search of the PubMed database for randomized controlled trials (RCT) published from inception to January 2019. The clinical outcomes of interest were overall survival and QoL. Where trials reported surrogate outcomes, we conducted additional PubMed searches for evidence of validity for predicting clinical outcomes and used guidance on surrogate outcome validation in oncology from the Institute for Quality and Efficiency in Health Care.ResultsEvidence on osimertinib, compared with chemotherapy, for patients with T790M-positive advanced NSCLC that has progressed after EGFR-TKI therapy was obtained from the AURA3 trial. In this study, overall survival data were immature and the results for QoL and symptom domains were not clinically meaningful. In addition, median progression-free survival (PFS) was six months longer for osimertinib than for chemotherapy. However, to date, no study has demonstrated that PFS reliably predicts longer survival or better QoL.ConclusionsOur HTA suggested that, unless proven, PFS should not be used as a valid surrogate outcome for decision making in public health. For example, the results of the AURA3 trial showed that osimertinib has an effect on the surrogate outcome of PFS in patients with EGFR T790M-positive advanced NSCLC that has progressed after first-line EGFR-TKI therapy, but not on the clinically relevant outcomes of overall survival and QoL. Furthermore, currently available evidence has failed to prove that PFS reliably predicts outcomes that are clinically relevant. Despite this, osimertinib has been given marketing authorization and is widely recommended in clinical guidelines.

Post-Progression Survival in Secondary EGFR T790M-Mutated Non-Small-Cell Lung Cancer Patients With and Without Osimertinib After Failure of a Previous EGFR TKI.

Osimertinib is effective in non-small-cell lung cancer (NSCLC) with an acquired epidermal growth factor receptor (EGFR) T790M mutation, the most common resistance mechanism to first- and second-generation EGFR tyrosine kinase inhibitors (TKIs). We aimed to evaluate survival outcome of patients with EGFR-mutant NSCLC who have progressed on previous EGFR TKI therapy. Advanced NSCLC patients with EGFR mutation after acquired resistance to first- or second-generation EGFR TKI who received tumor rebiopsy after EGFR TKI failure from 1 January 2012 to 31 December 2017 were reviewed. Patient clinical characteristics, T790M mutation status, and post-progression survival (PPS) were recorded by chart review. We included 240 patients and the percentage of secondary T790M mutations in first time tissue rebiopsy was 52.9%. 38 of the initial T790M-negative patients received second rebiopsies and 14 (36.8%) of these were T790M positive. The duration between first and second rebiopsy tended to be longer in patients who had T790M mutation in the second biopsy (11.5 vs. 6.9months, p = 0.043). After EGFR TKI failure, the median PPS of patients who had the T790M mutation and history of osimertinib use was 42.6months (95% CI 34.6-50.5), compared to 18.0 (95% CI 9.6-26.4) months in T790M-positive patients without a history of osimertinib use, and 18.8 (95% CI 9.3-28.4) months in patients with no T790M mutation (p < 0.0001). Multivariate analysis showed that history of osimertinib use was correlated with improved survival. These data further emphasize that osimertinib should be a standard of care in patients with pretreated EGFR T790M-positive NSCLC.

A phase II, multicenter, two cohort study of 160 mg osimertinib in EGFR T790M-positive non-small-cell lung cancer patients with brain metastases or leptomeningeal disease who progressed on prior EGFR TKI therapy

Up to 40% of patients with non-small-cell lung cancer (NSCLC) and epidermal growth factor receptor (EGFR) mutations treated with EGFR tyrosine kinase inhibitors (TKIs) present with disease progression in the central nervous system (CNS), either as brain metastases (BM) or leptomeningeal metastases (LM). Osimertinib (80 mg), a third-generation, irreversible, oral EGFR TKI, has shown efficacy in active CNS metastases. However, efficacy of osimertinib 160 mg in BM or LM is unclear. This prospective, single-arm, two cohort study evaluated the efficacy of osimertinib 160 mg in T790M-positive BM or LM NSCLC patients who progressed on prior EGFR TKI (NCT03257124) treatment. The primary end points were objective response rate (ORR) (H1= 30%) for the BM cohort and overall survival (OS) (H1= 5 months) for the LM cohort. The median follow-up duration was 10.1 months and 9.6 months for the BM and LM cohorts, respectively. In the BM cohort, intracranial ORR and disease control rate were 55.0% and 77.5%, respectively. The median progression-free survival (PFS) was 7.6 months [95% confidence interval (CI) 5.0-16.6]; the median OS was 16.9 months [95% CI 7.9-not reached (NR)]. In the LM cohort, intracranial disease control rate was 92.5% and complete response rate was 12.5%. The median OS was 13.3 months (95% CI 9.1-NR); the median PFS was 8.0 months (95% CI 7.2-NR). Subgroup analyses based on previous exposure to T790M-targeting agents, including osimertinib 80 mg or other third-generation EGFR TKIs, showed no difference in PFS in both the BM (n= 18, P= 0.39) and LM (n= 17, P=0.85) cohorts. Previous radiotherapy favored PFS in the BM cohort (hazard ratio 0.42, P= 0.04). The most common adverse events were decreased appetite, diarrhea, and skin rash; however, most were grade 1-2. Thus, osimertinib 160 mg demonstrated promising ORR and survival benefit with a tolerable safety profile in EGFR T790M-positive NSCLC patients with CNS metastasis who progressed on prior EGFR TKIs.

Next-generation sequencing of tissue and liquid rebiopsy favors post-progression outcomes of EGFR T790M-positive NSCLC patients treated with osimertinib.

e21563 Background: Osimertinib is standard of care for patients with advanced non–small-cell lung cancer (NSCLC) carrying acquired epidermal growth factor receptor ( EGFR) T790M mutation. However, few studies have been conducted to investigate the impact of rebiopsy on clinical outcomes after resistance to osimertinib. We evaluated whether next-generation sequencing (NGS) of tissue and liquid rebiopsy could favor post-progression outcomes of T790M-positive advanced NSCLC patients treated with osimertinib. Methods: Immediately just after resistance to second- or further-line osimertinib, advanced NSCLC patients with acquired EGFR T790M mutation were retrospectively divided into the NGS and non-NGS groups according to whether they underwent NGS of tissue or liquid rebiopsy. The co-primary endpoints were post-progression survival (PPS) defined as the time from osimertinib resistance to subsequent-line treatment resistance, and post-progression overall survival (pOS) defined as from osimertinib resistance to death or end of the last follow-up. Multivariable analyses were done using Cox proportional hazards regression model and log-rank test. Results: Between January 2017 and July 2019, 89 patients (62 vs. 27 for the NGS and non-NGS groups respectively) were eligible for final analyses. In the NGS group, 3.2% (2/62) underwent tissue rebiopsy only, 29.0% (18/62)only had liquid rebiopsy, and 66.8% (42/62)with both tissue and liquid rebiopsy.The NGS group received more targeted or combined therapy after resistance to osimertinib (62.9% vs. 40.8%, P= 0.053). The NGS group was significantly superior to the non-NGS group in the co-primary endpoints. The median PPS was 6.1 vs. 2.7 months (hazard ratio [HR], 0.49; 95%CI, 0.30 to 0.80; 2-sided log-rank P= 0.004). Meanwhile, the median pOS was 11.7 vs. 6.8 months (HR, 0.50; 95%CI, 0.29 to 0.85, 2-sided log-rank P= 0.009). Conclusions: Providing more opportunities for individualized treatment, NGS of tissue and liquid rebiopsy favors post-progression outcomes of EGFR T790M-positive advanced NSCLC patients treated with osimertinib.

Osimertinib for patients with poor performance status and EGFR T790M mutation-positive advanced non-small-cell lung cancer (NSCLC): A phase II clinical trial.

e21704 Background: Osimertinib has been shown to be effective against epidermal growth factor receptor ( EGFR) T790M-positive non-small cell lung cancer (NSCLC), but so far all clinical trials have targeted performance status (PS) 0 to 1 cases. The efficacy and safety of osimertinib in EGFR T790M-positive NSCLC patients with poor PS remain elusive. Methods: We conducted an open-label, multi-center, single-arm phase II study to evaluate the efficacy and safety of osimertinib in patients with EGFR T790M mutation-positive NSCLC who had Eastern Cooperative Oncology Group PS scores of 2 to 4. Patients received 80 mg of osimertinib once daily. The primary endpoint was progression-free survival (PFS). The planned sample size was 18 patients to achieve power of at least 80% with one-sided alpha of 0.05 and expected and threshold PFS as 8.2 months and 3.0 months. Results: Eighteen patients (4 men and 14 women) were enrolled between June 2017 and November 2018. The median age was 77 years (range: 55–85 years). Ten, six, and two patients had PS scores of 2, 3, and 4, respectively. All patients had adenocarcinoma with common EGFR mutations and were previously treated with first- or second-generation EGFR- tyrosine kinase inhibitors, and 10 patients (56%) had central nervous system (CNS) metastasis. The overall median PFS was 7.0 months (90% confidence interval: 5.5-8.9 months). The overall response rate (ORR) was 53%, the median time to first response was 1.5 months, the median duration of response was 6.7 months, and the median overall survival (OS) was 12.7 months. Moreover, improved PS scores were observed in 13 patients (72%) including six with PS 2, six with PS 3, and one with PS 4. Osimertinib also showed an ORR of 60% in the patients with CNS metastasis, and the median PFS and OS were 6.5 months and 22.0 months, respectively. Although anemia, rash, and anorexia were frequently reported, the incidence of grade 3 adverse events was low, and no grade 4 or 5 events were observed. Interstitial lung disease (ILD) was observed in three patients (two with grade 2, one with grade 1). All three patients discontinued osimertinib treatment and recovered from ILD. Conclusions: Osimertinib therapy could be a promising treatment option for patients with EGFR T790M mutation-positive advanced NSCLC who have poor PS. Clinical trial information: UMIN000027655.

Osimertinib, a third-generation EGFR tyrosine kinase inhibitor: A retrospective multicenter study of its real-world efficacy and safety in advanced/recurrent non-small cell lung carcinoma.

BackgroundOsimertinib is recommended for T790M mutation‐positive advanced non‐small cell lung cancer (NSCLC) resistant to first‐ and second‐generation epidermal growth factor receptor (EGFR)‐tyrosine kinase inhibitors (TKIs). Recently, some reports exist on the real‐world use of osimertinib; however, reports involving third/later‐line use are few. Hence, this study was conducted to evaluate the efficacy and safety of osimertinib used in various treatment lines for T790M‐positive NSCLC patients.MethodsThis retrospective, observational, multicenter study included T790M‐positive advanced/recurrent NSCLC patients treated with osimertinib from May 2016 to March 2018. The clinical characteristics, efficacy, and adverse events were retrospectively investigated. The Kaplan‐Meier method was used to analyze progression‐free survival (PFS) and overall survival (OS). PFS‐associated clinical characteristics were evaluated using the Cox proportional hazards model.ResultsThe objective response rate (ORR) and disease control rate (DCR) were 60.7% and 91.1%, respectively; the median PFS was 11.0 months. There were no significant differences in the median PFS for patients treated with osimertinib as second‐line and third−/later‐line (14.5 vs. 11.0 months respectively, P = 0.327). Analysis using the Cox proportional hazards model for clinical features affecting PFS also revealed no significant factors. Adverse events of grade ≥ 3 were reported in 15 patients (26.8%); the most common were anemia (n = 3) and cutaneous toxicity (n = 3). Grade 4 neutropenia was observed in one patient; any‐grade pneumonitis was observed in six patients (10.7%), including one with grade 3 pneumonitis.ConclusionsOsimertinib demonstrated efficacy even when administered as third−/later‐line treatment to NSCLC patients. Osimertinib‐related pneumonitis was observed more frequently than previously reported.Key pointsSignificant findings of the studyOsimertinib shows efficacy even as later‐line treatment in T790M mutation‐positive NSCLC patients previously treated with EGFR‐TKIs. However, the incidence of ≥ grade 3 adverse events, especially pneumonitis, was higher than that previously reported by other studies.What this study addsOsimertinib was approved for previously EGFR‐TKI‐treated EGFR T790M‐positive NSCLC. With the increasing frequency of its use as first‐line treatment, this study provides valuable evidence for the efficacy and safety of osimertinib for previously EGFR‐TKI‐treated NSCLC.

Determination of Somatic Mutations and Tumor Mutation Burden in Plasma by CAPP-Seq during Afatinib Treatment in NSCLC Patients Resistance to Osimertinib

Third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) were developed to target the EGFR T790M resistance mutation in non-small cell lung cancer (NSCLC) patients resistant to first- or second-generation EGFR-TKIs. To investigate the efficacy of afatinib treatment for EGFR T790M-positive NSCLC patients showing resistance to osimertinib and alterations in somatic mutations and tumor mutation burden (TMB) in plasma circulating tumor DNA (ctDNA) during afatinib treatment, we conducted a prospective study using Cancer Personalized Profiling by deep Sequencing (CAPP-Seq). Nine NSCLC patients with EGFR T790M mutation who showed resistance to third-generation EGFR-TKIs were enrolled in this study and treated with afatinib. Plasma samples were collected before treatment, 4 weeks after treatment, and at disease progression. The mutation profile and TMB in plasma ctDNA were analyzed by CAPP-Seq. The objective response rate and median progression-free survival associated with afatinib were 0% and 2.0 months, respectively. The C797S mutation-mediated resistance to osimertinib was observed in one patient and following afatinib treatment in two patients; the C797S mutations occurred in the same allele as the T790M mutation. After afatinib treatment, afatinib-sensitive mutant alleles, such as ERBB2, and TMB decreased. We have demonstrated that detection of mutant allele frequency and TMB of ctDNA by CAPP-Seq could help determine the effectiveness of and resistance to afatinib. Although afatinib monotherapy for T790M-positive NSCLC resistant to osimertinib was less effective, the action for multiclonal mutant alleles and TMB might contribute to further treatment strategy.

Observational Study of Treatment Patterns in Patients with Epidermal Growth Factor Receptor (EGFR) Mutation-Positive Non-Small Cell Lung Cancer After First-Line EGFR-Tyrosine Kinase Inhibitors

Epidermal growth factor receptor (EGFR) mutations are observed in approximately 15% of patients with non-small cell lung cancer (NSCLC) in the USA. Little is known about treatment patterns in EGFR mutation-positive NSCLC following progression on or after first-line (1L) treatment with first- or second-generation EGFR tyrosine kinase inhibitors (EGFR-TKIs). Osimertinib, a third-generation EGFR-TKI, is a treatment option for patients with EGFR T790M-positive NSCLC following progression on 1L EGFR-TKIs. This study analyzed real-world treatment sequencing of EGFR-TKIs, EGFR T790M testing rates, and disposition of patients with EGFR mutations after 1L EGFR-TKI post-FDA approval of osimertinib in patients with EGFR mutation-positive NSCLC. Adult patients with stageIV NSCLC and documented EGFR mutation-positive status were identified between December 1, 2015 and May 31, 2017 from the US Oncology Network iKnowMed™ electronic health record (EHR). Data were abstracted from the EHR database and supplemented by chart review. Of 308 patients, 302 (98%) received an EGFR-TKI overall, and 246 patients (80%) received a 1L EGFR-TKI. The most common 1L EGFR-TKI was erlotinib (66%); the remaining 1L regimens were predominantly combination chemotherapies with or without an EGFR-TKI. Only 80 patients (26%) received any 2L therapy. The most common EGFR-TKIs used as 2L monotherapy in patients who received 1L EGFR-TKI were afatinib and osimertinib (n = 7 for both). Among all patients treated with 1L EGFR-TKI (n = 246), 47 (19%) were tested for EGFR T790M [16 patients (34%) were positive], 48 (20%) remained on 1L EGFR-TKI, 29 (12%) received subsequent therapy, 38 (15%) had died on or after their 1L EGFR-TKI therapy, and 131 (53%) stopped their EGFR-TKI with no recorded evidence of having received subsequent therapy at follow-up end. Following 1L EGFR-TKI treatment, 19% of patients were tested for EGFR T790M, and most (69%) had no record of receiving any subsequent therapy.

1521P - Osimertinib in epidermal growth factor receptor (EGFR) T790M advanced non-small cell lung cancer (NSCLC): Analysis of patients with central nervous system (CNS) metastases in a real-world study (ASTRIS)

BackgroundApproximately 20%–30% of patients (pts) with EGFR mutation-positive NSCLC present with CNS metastases at the time of diagnosis of advanced disease. CNS metastases are associated with a poor prognosis. Osimertinib is a third-generation, irreversible, oral EGFR-tyrosine kinase inhibitor (TKI) that potently and selectively inhibits both EGFR-TKI sensitising (EGFRm) and EGFR T790M mutations and in clinical trials has demonstrated efficacy in NSCLC CNS metastases. ASTRIS is the largest ongoing, international, real-world study of osimertinib in EGFR T790M positive advanced NSCLC (NCT02474355). We report a subset analysis of pts with CNS metastases. MethodsEligible pts with stage IIIB/IV EGFR T790M positive NSCLC previously treated with an EGFR-TKI received osimertinib 80mg once-daily. Investigator-assessed (IA) progression-free survival (PFS), clinical response and time to treatment discontinuation (TTD) were analysed in a subset of pts with CNS (leptomeningeal and/or brain) metastases at baseline (BL). Follow-up brain imaging was not mandatory. ResultsFrom 18 September 2015 to 15 October 2018, 3015 pts across 16 countries had received ≥1 dose of osimertinib (full analysis set [FAS]); 882 (29%) pts presented with CNS metastases at BL. BL demographics were similar between this subset and the FAS (female: 63%/64%; Asian: 69%/69%; median age (range): 61 (27–88) years/62 (27–92); WHO performance status 2: 15%/11%). IA response rates were consistent across the two groups, while median PFS and TTD appeared to be slightly lower in the CNS subset (Table). Overall survival data are immature. ConclusionsIn a real-world setting, over half of pts with EGFR T790M positive advanced NSCLC and CNS metastases responded to treatment with osimertinib 80mg. These findings support previous clinical research showing clinically meaningful CNS efficacy with osimertinib in advanced NSCLC.Table1521P Clinical outcomes for pts with EGFR T790M advanced NSCLC and CNS metastases at BLTableClinical outcomesFAS Osimertinib 80mg (N=3015)CNS subset Osimertinib 80mg (N=882)Response rate*, % (95% CI)57 (55, 59)59 (55, 62)Best overall response†, n (%) Responding Stable disease Progressive disease Unknown1655 (55) 1043 (35) 202 (7) 115 (4)485 (55) 274 (31) 66 (7) 57 (6)Median PFS, months (95% CI)11.1 (11.0, 12.0)9.7 (9.2, 10.5)Median TTD, months (95% CI)13.5 (12.6, 13.9)11.1 (10.1, 12.1)CI, confidence interval*Response rate is defined as the percentage of pts with a best response of ’Responding’ by investigator assessment, based on pts with ≥1 documented response assessment. 95% CI is defined by Clopper-Pearson method †Best overall response is defined as the best response by investigator assessment. Pts with no assessments were considered as ’Unknown’ Clinical trial identificationNCT02474355. Editorial acknowledgementBernadette Tynan, MSc, of iMed Comms, Macclesfield, UK, an Ashfield Company, part of UDG Healthcare plc, funded by AstraZeneca. Legal entity responsible for the studyAstraZeneca. FundingAstraZeneca. DisclosureM. Provencio: Advisory / Consultancy: BMS, MSD, AstraZeneca, BI; Travel / Accommodation / Expenses: MSD, AstraZeneca. D. Kim: Research grant / Funding (institution): Alpha Biopharma, AstraZeneca/MedImmune, Hanmi, Janssen, Merus, Mirati Therapeutics, MSD, Novartis, Ono Pharmaceutical, Pfizer, Roche/Genentech, Takeda, TP Therapeutics, Xcovery, Yuhan. B.C. Cho: Honoraria (institution): Novartis, Bayer, AstraZeneca, MOGAM Institute, Dong-A ST, Champions Oncology, Janssen, Yuhan, Ono, Dizal Pharma, MSD, Boehringer Ingelheim, Roche, BMS, Pfizer, Eli Lilly, Takeda, TheraCanVac Inc.; Advisory / Consultancy: Novartis, Bayer, AstraZeneca, MOGAM Institute, Dong-A ST, Champions Oncology, Janssen, Yuhan, Ono, Dizal Pharma, MSD, Boehringer Ingelheim, Roche, BMS, Pfizer, Eli Lilly, Takeda, TheraCanVac Inc.; Speaker Bureau / Expert testimony: Novartis; Research grant / Funding (institution): Novartis, Bayer, AstraZeneca, MOGAM Institute, Dong-A ST, Champions Oncology, Janssen, Yuhan, Ono, Dizal Pharma, MSD; Shareholder / Stockholder / Stock options: TheraCanVac Inc.; Licensing / Royalties: Champions Oncology. K. Park: Advisory / Consultancy: AMGEN, AstraZeneca, Astellas, BluePrint, Eli Lilly, Hanmi, KHK, MSD, Boehringer Ingelheim, Roche, Merck KGaA, Ono; Speaker Bureau / Expert testimony: Boehringer Ingelheim; Research grant / Funding (self): AstraZeneca. R. Migliorino: Advisory / Consultancy: AstraZeneca, MSD, BI, Pfizer, Roche, BMS; Speaker Bureau / Expert testimony: AstraZeneca, MSD, BI, Pfizer, Roche, BMS; Travel / Accommodation / Expenses: AstraZeneca, MSD, BI, Pfizer, Roche, BMS. M. Tiseo: Advisory / Consultancy: AstraZeneca, BMS, MSD, Boehringer Ingelheim, Takeda; Research grant / Funding (institution): AstraZeneca. Q. Zhou: Honoraria (self): AstraZeneca, Roche. A. Santo: Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): AstraZeneca, Roche. A. Ardizzoni: Honoraria (self): MSD, BMS, Pfizer, Eli Lilly; Advisory / Consultancy: MSD, Roche; Research grant / Funding (institution): BMS, Celgene, Roche. Y. Wu: Honoraria (self): AstraZeneca, Roche, Eli Lilly, Pfizer, MSD, BMS, Boehringer Ingelheim; Advisory / Consultancy: AstraZeneca, Roche, Boehringer Ingelheim; Research grant / Funding (institution): AstraZeneca, Roche. S. Kim: Advisory / Consultancy, Research grant / Funding (institution): AstraZeneca. M. Miranda: Shareholder / Stockholder / Stock options, Full / Part-time employment: AstraZeneca PLC. A. Fernandes: Shareholder / Stockholder / Stock options, Full / Part-time employment: AstraZeneca. F. de Marinis: Honoraria (self), Travel / Accommodation / Expenses: Roche; Advisory / Consultancy: Roche, Celgene, MSD, BMS, AstraZeneca, Takeda, Pfizer; Research grant / Funding (self): Boehringer Ingelheim, MSD. All other authors have declared no conflicts of interest.

EP1.01-68 Impact of EGFR Genotype on the Efficacy of Osimertinib in Patients with Non-Small Cell Lung Cancer: A Prospective Observational Study

A T790M of the epidermal growth factor receptor (EGFR) is the most frequently encountered mutation occurring acquired resistance to EGFR tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer (NSCLC). The aim of this study was to assess the differential clinical outcomes of osimertinib therapy in NSCLC patients with T790M according to the type of active EGFR mutation, i.e. exon 19 deletion or L858R point mutation. We conducted a prospective observational cohort study to evaluate the efficacy and safety of osimertinib in patients with major EGFR mutation and T790M-positive advanced NSCLC who had disease progression after first-line EGFR-TKI therapy. The efficacy of osimertinib was evaluated according to the type of EGFR mutation. A total of 51 patients were included in this study. The exon 19 deletion was found in 33 (65%) patients, and the L858R point mutation in 18 patients (35%). An objective response was obtained in 29 patients, indicating an objective response rate of 58.8%. The response rate was 69.7% in patients with exon 19 deletion and 38.9% in patients with L858R point mutation, indicating a statistically significant difference (P =0.033). The median progression-free survival (PFS) and overall survival (OS) of the entire patient population were 7.8 and 15.5 months, respectively. Median PFS in the exon 19 deletion and L858R point mutation groups was 8.0 months and 5.2 months, respectively, indicating a statistically significant difference (P =0.045). Median OS in the exon 19 deletion and L858R point mutation groups was 19.8 months and 12.9 months, respectively, indicating a statistically significant difference (P =0.0015). Multivariate analysis identified exon 19 deletion as a favorable independent predictor of PFS and OS. Investigators should consider the proportions of sensitive EGFR mutation types as a stratification factor in designing or reviewing clinical studies involving osimertinib.

Two cases of congestive heart failure during osimertinib treatment for EGFR mutant NSCLC

Abstract We herein report two case of fatal congestive heart failure during osimertinib treatment for epidermal growth factor receptor (EGFR) mutant non-small cell lung cancer (NSCLC). Case1: A 66-year-old woman presented with progressive palpitation and dyspnea two months after starting osimertinib for the treatment of EGFR T790M-positive NSCLC. An echocardiogram demonstrated severe decreased left ventricular systolic function. She was diagnosed with fatal congestive heart failure caused by osimertinib treatment. Her general condition deteriorated, and she died three months after starting osimertinib. Case2: A 84-year-old woman was treated for recurrent EGFR mutant NSCLC after lobectomy, and osimertinib was administered. Severe exertional dyspnea appeared one month after starting osimertinib. She was also diagnosed with fatal congestive heart failure caused by osimertinib, and died for a few days. The causal relationship between osimertinib and cardiotoxicity has so far received little attention and thus remains unclear. Osimertinib inhibits HER2 (ERBB2) in addition to EGFR (ERBB1), thereby potentially causing cardiotoxicity.

Impact of EGFR genotype on the efficacy of osimertinib in EGFR tyrosine kinase inhibitor-resistant patients with non-small cell lung cancer: a prospective observational study.

Purpose: A T790M of the epidermal growth factor receptor (EGFR) is the most frequently encountered mutation conferring acquired resistance to EGFR tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer (NSCLC). The aim of this study was to assess the differential clinical outcomes of osimertinib therapy in NSCLC patients with T790M according to the type of activating EGFR mutation, ie, exon 19 deletion or L858R point mutation.Patients and methods: A prospective observational cohort study was conducted to evaluate the efficacy and safety of osimertinib in patients with a major EGFR mutation and T790M-positive advanced NSCLC who had disease progression after first-line EGFR-TKI therapy. The efficacy of osimertinib was evaluated according to the type of EGFR mutation.Results: A total of 51 patients were included in this study. An objective response was obtained in 29 patients, indicating an objective response rate of 58.8%. The response rate was 69.7% in patients with exon 19 deletion and 38.9% in patients with L858R point mutation, indicating a statistically significant difference (P=0.033). The median progression-free survival (PFS) and overall survival (OS) of the entire patient population were 7.8 and 15.5 months, respectively. The median PFS in the exon 19 deletion and L858R point mutation groups was 8.0 months and 5.2 months, respectively, indicating a statistically significant difference (P=0.045). Median OS in the exon 19 deletion and L858R point mutation groups was significantly different at 19.8 months and 12.9 months, respectively (P=0.0015). Multivariate analysis identified the exon 19 deletion as a favorable independent predictor of PFS and OS.Conclusion: Investigators should consider the proportions of sensitive EGFR mutation types as a stratification factor in designing or reviewing clinical studies involving osimertinib.

Analysis of resistance mechanisms to abivertinib, a third-generation EGFR tyrosine kinase inhibitor, in patients with EGFR T790M-positive non-small cell lung cancer from a phase I trial.

BackgroundResistance to third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) presents a major clinical challenge in advanced non-small cell lung cancer (NSCLC). Here, we report resistance mechanisms to abivertinib, a novel third-generation EGFR TKI, from a phase I dose-escalation/expansion study (NCT02330367).MethodsPatients with EGFR T790M-positive advanced NSCLC and progression on prior EGFR TKIs received abivertinib in dose escalation (50–350 mg twice daily [BID]) or expansion (300 mg BID) cohorts. Patients enrolled at Guangdong Lung Cancer Institute who underwent next-generation sequencing (NGS)-based genomic profiling upon abivertinib progression (prior to October 30, 2018) were enrolled in this exploratory analysis.FindingsThirty of 73 patients enrolled were eligible for resistance analysis. Upon abivertinib progression, 27 patients provided plasma samples (six patients also provided paired samples from the progression sites) and three patients only provided tissue samples from the progression sites for NGS. A heterogeneous landscape of resistance to abivertinib was observed: 15% (4/27) experienced EGFR T790M loss and 13% (4/30) developing EGFR tertiary mutations including C797S. EGFR amplification was observed in 11 patients (37%), and considered a putative resistance mechanism in seven (23%) patients. Other EGFR-independent resistance mechanisms involved CDKN2A, MET, PIK3CA, HER2, TP53, Rb1 and small-cell lung cancer transformation.InterpretationOur findings reveal a heterogenous pattern of resistance mechanisms to abivertinib which is distinct from that previously reported with osimertinib. EGFR amplification was the most common resistance mechanism in this cohort.FundThe National Key R&D Program of China (Grant No. 2016YFC1303800), Key Lab System Project of Guangdong Science and Technology Department – Guangdong Provincial Key Lab of Translational Medicine in Lung Cancer (Grant No. 2012A061400006/2017B030314120).