EGFR Mutation-positive NSCLC Research Articles

Durvalumab, Tremelimumab, and Platinum Chemotherapy in EGFR Mutation–Positive NSCLC: An Open-Label Phase 2 Trial (ILLUMINATE)

IntroductionEGFR-mutant NSCLC is associated with low mutation burden and low levels of PD-L1 expression. We conducted a phase 2 trial to determine the efficacy of durvalumab, tremelimumab, and platinum-pemetrexed in EGFR-mutant NSCLC after progression with EGFR tyrosine kinase inhibitors (TKIs). MethodsParticipants were treated with induction durvalumab, tremelimumab, and platinum-pemetrexed, followed by durvalumab-pemetrexed maintenance. Participants were divided into two cohorts: (1) EGFR exon 20 T790M negative (T790M−, progressing on either first-line osimertinib, or on a single line of first/second generation TKI), and (2) T790M positive (T790M+, progressing on greater than or equal to 1 lines of TKI, including osimertinib). The primary endpoint was the confirmed objective response rate (ORR) assessed by the investigators. Progression-free survival and safety were secondary outcomes. ResultsOne hundred participants from Australia and Taiwan were enrolled. Median follow-up was 26 months with 88% and 96% experiencing progression events for T790M− and T790M+, respectively. The ORR for T790M− was 31% (95% confidence interval: 20–45), including two complete responses. The ORR for T790M+ was 21% (95% confidence interval: 12–34). Median durations of response were 9.5 months and 6.3 months for T790M− and T790M+, respectively; median progression-free survival rates were 6.5 months and 4.9 months, respectively. For T790M−, ORR was 27% for 50% or higher PD-L1 (N = 22) and 0% for less than 50% PD-L1 (N = 10), respectively. For T790M+, ORR was 17% for 50% or higher PD-L1 (N = 24). The safety profile was consistent with previous reports. ConclusionsDurvalumab, tremelimumab, and platinum-pemetrexed had modest anti-tumor activity in EGFR-mutant NSCLC after progression on TKI. The T790M− cohort had higher ORR and a longer duration of response. Immune adverse events were not increased with tremelimumab. The clinical registration number of this trial is NCT03994393.

EP.12A.08 Furmonertinib as First-Line Therapy for Chinese Patients with EGFR Mutation-positive NSCLC: A Real-World Study

EP.12A.08 Furmonertinib as First-Line Therapy for Chinese Patients with EGFR Mutation-positive NSCLC: A Real-World Study

P1.12A.06 A Phase II 80 Mg Osimertinib in Patients with Leptomeningeal Metastases Associated with EGFR Mutation-Positive NSCLC (BLOSSOM)

P1.12A.06 A Phase II 80 Mg Osimertinib in Patients with Leptomeningeal Metastases Associated with EGFR Mutation-Positive NSCLC (BLOSSOM)

Initial AXL and MCL-1 inhibition contributes to abolishing lazertinib tolerance in EGFR-mutant lung cancer cells.

Lazertinib, a novel third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), demonstrates marked efficacy in EGFR-mutant lung cancer. However, resistance commonly develops, prompting consideration of therapeutic strategies to overcome initial drug resistance mechanisms. This study aimed to elucidate the adaptive resistance to lazertinib and advocate novel combination treatments that demonstrate efficacy in preventing resistance as a first-line treatment for EGFR mutation-positive NSCLC. We found that AXL knockdown significantly inhibited lung cancer cell viability in the presence of lazertinib, indicating that AXL activation contributes to lazertinib resistance. However, long-term culture with a combination of lazertinib and AXL inhibitors led to residual cell proliferation and increased the MCL-1 expression level, which was mediated by the nuclear translocation of the transcription factor YAP. Triple therapy with an MCL-1 or YAP inhibitor in combination with lazertinib and an AXL inhibitor significantly reduced cell viability and increased the apoptosis rate. These results demonstrate that AXL and YAP/MCL-1 signals contribute to adaptive lazertinib resistance in EGFR-mutant lung cancer cells, suggesting that the initial dual inhibition of AXL and YAP/MCL-1 might be a highly effective strategy in eliminating lazertinib-resistant cells.

High-cost treatments for advanced lung cancer in Japan (Lung Cancer Study Group of the Japan Clinical Oncology Group).

The treatment of lung cancer has made dramatic progress in the past decade, but due to the high cost of drugs, the total pharmaceutical cost has been rising explosively. There are currently no data available in Japan on which regimens are used, to what extent they are used, and what their total cost is. Sixty Japanese centers belonging to the Lung Cancer Study Group of the Japan Clinical Oncology Group were surveyed for information about the first-line treatment for advanced lung cancer in practice from July 2021 to June 2022. Three types of cancer were included: driver gene mutation-negative NSCLC, EGFR mutation-positive NSCLC, and extensive-stage small cell lung cancer (ES-SCLC). Recent treatment costs for ICIs or ICI plus chemotherapy were about 20-55 times higher than those for conventional chemotherapy. Of the 3738 patients with driver gene aberration-negative NSCLC, 2573 (68.8%) received treatments with monthly cost of 500 000 Japanese yen (JPY) or more; 2555 (68.4%) received ICI therapy. Of the 1486 patients with EGFR mutation-positive NSCLC, 1290 (86.8%) received treatments with a monthly cost of 500 000 JPY or more; 1207 (81.2%) received osimertinib. ICI treatments with a monthly cost of 500 000 JPY or more were administered to 607 (56.3%) of 1079 patients with ES-SCLC. Elderly NSCLC patients received slightly more high-cost treatment than younger patients. Recent treatments cost many times more than conventional chemotherapy. This study revealed that high-cost treatments were widely used in advanced lung cancer and some of high-cost treatments were used despite the lack of clear evidence. Physicians should pay attention to the cost of treatments they use.

Longitudinal Analyses of Circulating Tumor DNA for the Detection of EGFR Mutation-Positive Advanced NSCLC Progression During Treatment: Data From FLAURA and AURA3

IntroductionEGFR tyrosine kinase inhibitor (EGFR-TKI)-sensitizing and -resistance mutations may be detected in plasma through circulating tumor DNA (ctDNA). Circulating tumor DNA level changes reflect alterations in tumor burden and could be a dynamic indicator of treatment effect. This analysis aimed to determine whether longitudinal EGFR-mutation ctDNA testing could detect progressive disease (PD) before radiologic detection. MethodsThis was a retrospective, exploratory ctDNA analysis in two phase 3 trials (FLAURA, NCT02296125; AURA3, NCT02151981). Patients had treatment-naïve (FLAURA) or EGFR-TKI pre-treated (AURA3) advanced NSCLC with EGFR mutations and on-study PD (RECIST [Response Evaluation Criteria in Solid Tumors]), with a baseline ctDNA result and EGFR-mutation ctDNA monitoring beyond Cycle 3 Day 1. Patients received osimertinib versus comparator EGFR-TKIs (FLAURA) or chemotherapy (AURA3). Outcomes included time from ctDNA PD to RECIST PD and the first subsequent treatment (FLAURA only). ResultsCirculating tumor DNA PD preceded or co-occurred with RECIST-defined PD in 93 out of 146 patients (64%) in FLAURA and 82 out of 146 patients (56%) in AURA3. Median time from ctDNA PD to RECIST-defined PD (mo) was 3.4 and 2.6 in the osimertinib and comparator EGFR-TKI arms (FLAURA) and 2.8 and 1.5 in the osimertinib and chemotherapy arms (AURA3). In FLAURA, the median time from ctDNA PD to the first subsequent treatment (mo) was 6.0 and 4.7 in the osimertinib (n = 51) and comparator EGFR-TKI arms (n = 70). ConclusionsAmong patients with EGFR mutation-positive advanced NSCLC receiving EGFR-TKI or chemotherapy with ctDNA data and RECIST-defined PD, ctDNA PD preceded/co-occurred with RECIST-defined PD in approximately 60% of cases. Longitudinal ctDNA monitoring may detect PD before radiologic PD.

Phosphoproteomic Analysis Identified Mutual Phosphorylation of FAK and Src as a Mechanism of Osimertinib Resistance in EGFR-Mutant Lung Cancer

IntroductionOsimertinib is a standard treatment for patients with EGFR-mutant NSCLC. Although some osimertinib resistance mechanisms have been identified, nearly 50% of the mechanisms remain to be elucidated. This study was aimed at identifying non-genetic mechanisms underlying osimertinib resistance. MethodsWe established two osimertinib-resistant cell lines from EGFR mutation-positive PC-9 and HCC827 NSCLC cell lines (PC-9OR and HCC827OR, respectively) using a stepwise method. We compared the phosphoproteomic profiles of the osimertinib-resistant and parental cells using mass spectrometry. Upstream kinases were identified using the application Kinase Enrichment Analysis version 3. ResultsPhosphoproteomic analysis revealed 80 phosphorylation sites that were mutually up-regulated in PC-9OR and HCC827OR cells. The Kinase Enrichment Analysis version 3 analysis identified focal adhesion kinase (FAK) and proto-oncogene tyrosine-protein kinase Src (Src) as upstream kinases of these up-regulated phosphoproteins. The small-interfering RNA–mediated knockdown of FAK reduced Src phosphorylation and that of Src reduced FAK phosphorylation in both cell lines. Furthermore, FAK- or Src-specific small-interfering RNA treatments restored EGFR phosphorylation in PC-9OR and HCC827OR cells. The combination of FAK and Src inhibitors inhibited PC-9OR and HCC827OR cell proliferation in vitro and suppressed tumor growth in a xenograft mouse model. Immunohistochemistry of tumors from patients with EGFR-mutant NSCLC suggested that phosphorylated FAK and Src are involved in initial and acquired resistance to osimertinib. ConclusionsPhosphoproteomic analysis may help elucidate the mechanisms of resistance to molecular-targeted therapies in lung cancer. Mutual phosphorylation of FAK and Src is involved in osimertinib resistance. Thus, FAK and Src inhibition may be novel treatment strategies for osimertinib-resistant NSCLC.

Brief Report: Risk of Recurrent Interstitial Lung Disease From Osimertinib Versus Erlotinib Rechallenge After Symptomatic Osimertinib-Induced Interstitial Lung Disease

IntroductionInterstitial lung disease (ILD) is the most frequent cause of drug-related mortality from EGFR tyrosine kinase inhibitors (TKIs). Yet, for patients with symptomatic osimertinib-induced ILD, the risk of recurrent ILD associated with EGFR TKI rechallenge, either with osimertinib or another TKI, such as erlotinib, is unclear. MethodsRetrospective study of 913 patients who received osimertinib treatment for EGFR mutation-positive NSCLC. Clinical characteristics, ILD treatment history, and subsequent anticancer therapy of patients with symptomatic osimertinib-induced ILD were collated. The primary end point was to compare the incidence of recurrent ILD with osimertinib versus erlotinib rechallenge. ResultsOf 913 patients, 35 (3.8%) had symptomatic osimertinib-induced ILD, of which 12 (34%), 15 (43%), and eight (23%) had grade 2, 3 to 4, and 5 ILD, respectively. On ILD recovery, 17 patients had EGFR TKI rechallenge with eight received osimertinib and nine received erlotinib. The risk of recurrent ILD was higher with osimertinib rechallenge than erlotinib (p = 0.0498). Of eight, five (63%) developed recurrent ILD on osimertinib rechallenge, including three patients with fatal outcomes. In contrast, only one of nine patients (11%) treated with erlotinib had recurrent ILD. Median time to second ILD occurrence was 4.7 (range 0.7–12) weeks. Median time-to-treatment failure of patients with erlotinib rechallenge was 13.2 months (95% confidence interval: 8.6–15.0). ConclusionsThe risk of recurrent ILD was considerably higher with osimertinib rechallenge than erlotinib. Osimertinib rechallenge should be avoided, whereas erlotinib may be considered in patients with symptomatic osimertinib-induced ILD.

Treatment decision for recurrences in non-small cell lung cancer during or after adjuvant osimertinib: an international Delphi consensus report.

Osimertinib is recommended by major guidelines for use in the adjuvant setting in patients with EGFR mutation-positive NSCLC following the significant improvement in disease-free survival observed in the Phase III ADAURA trials. Due to limited real-world data in the adjuvant setting, little guidance exists on how to approach potential recurrences either during or after the completion of the treatment. This study aimed to reach a broad consensus on key treatment decision criteria in the events of recurrence. To reach a broad consensus, a modified Delphi panel study was conducted consisting of two rounds of surveys, followed by two consensus meetings and a final offline review of key statements. An international panel of experts in the field of NSCLC (n=12) was used to provide clinical insights regarding patient management at various stages of NSCLC disease including patient monitoring, diagnostics, and treatment approach for specific recurrence scenarios. This study tested recurrences occurring 1) within or outside the central nervous system (CNS), 2) during or after the adjuvant-osimertinib regimen in NSCLC disease which is 3) amenable or not amenable to local consolidative therapy. Panellists agreed on various aspects of patient monitoring and diagnostics including the use of standard techniques (e.g., CT, MRI) and tumour biomarker assessment using tissue and liquid biopsies. Consensus was reached on 6 statements describing treatment considerations for the specific NSCLC recurrence scenarios. Panellists agreed on the value of osimertinib as a monotherapy or as part of the overall treatment strategy within the probed recurrence scenarios and acknowledged that more clinical evidence is required before precise recommendations for specific patient populations can be made. This study provides a qualitative expert opinion framework for clinicians to consider within their treatment decision-making when faced with recurrence during or after adjuvant-osimertinib treatment.

Adjuvant Osimertinib in Patients With Stage IB to IIIA EGFR Mutation-Positive NSCLC After Complete Tumor Resection: ADAURA China Subgroup Analysis

IntroductionIn Chinese patients with NSCLC, prevalence of EGFR-mutated (EGFRm) disease is high. In the global phase 3 ADAURA study (NCT02511106), adjuvant osimertinib was found to have a statistically significant and clinically meaningful improvement in disease-free survival (DFS) versus placebo in resected stage IB to IIIA EGFRm NSCLC. We present efficacy and safety data from a subgroup analysis of 159 Chinese patients enrolled in the People’s Republic of China from ADAURA. MethodsIn ADAURA, patients with completely resected stage IB to IIIA EGFRm (exon 19 deletion/exon 21 L858R) NSCLC were randomized 1:1 to receive osimertinib (80 mg once daily) or placebo for 3 years or until disease recurrence/discontinuation. Adjuvant chemotherapy was permitted before randomization, per physician/patient choice. Primary end point was investigator-assessed DFS in stage II to IIIA disease; secondary end points included DFS in stage IB to IIIA (overall population), overall survival, health-related quality of life (HRQoL), and safety. ResultsOf 682 patients enrolled globally, 159 patients in the People’s Republic of China were included in this subgroup analysis (osimertinib n = 77; placebo n = 82). Baseline characteristics were balanced across the treatment arms. At data cutoff, stage II to IIIA DFS hazard ratio (HR) was 0.23 (95% confidence interval [CI]: 0.13–0.42; maturity 59%); stage IB to IIIA DFS HR was 0.29 (95% CI: 0.17–0.48; maturity 42%). At 13% maturity (21 deaths), HR for overall survival in the stage IB to IIIA population was 0.51 (95% CI: 0.21–1.20). HRQoL was maintained from baseline, and safety was consistent with the global population. ConclusionsIn this population of Chinese patients from ADAURA, adjuvant osimertinib was found to have a clinically meaningful improvement in DFS versus placebo, with maintained HRQoL and a safety profile consistent with the global study population.

Brief Report: Circular Runt-related transcription factor (circRUNX1) as potential biomarker for cancer recurrence in EGFR mutation-positive surgically resected NSCLC

IntroductionAs recently evidenced by the ADAURA trial, most patients with stages IB to IIIA of resected EGFR-mutant lung adenocarcinoma benefit from osimertinib as adjuvant therapy. Nevertheless, predictive markers of response and recurrence are still an unmet need for more than 10% of these patients. Some circular RNAs (circRNAs) have been reported to play a role in tumor growth and proliferation. In this project, we studied circRNA expression levels in formalin-fixed, paraffin-embedded lung tumor samples to explore their biomarker potential and develop a machine learning (ML)-based signature that could predict the benefit of adjuvant EGFR tyrosine kinase inhibitors in patients with EGFR-mutant NSCLC. MethodsPatients with surgically resected EGFR mutant-positive, stages I to IIIB NSCLC were recruited from February 2007 to December 2015. Formalin-fixed, paraffin-embedded tumor samples were retrospectively collected from those patients with a follow-up period of more than or equal to 36 months (N = 76). Clinicopathologic features were annotated. Total RNA was purified and quantified prior nCounter processing with our circRNA custom panel. Data analysis and ML were performed taking into consideration circRNA expression levels and recurrence-free survival (RFS). RFS was defined from the day of surgery to the day when recurrence was detected radiologically or the death owing to any cause. ResultsOf the 76 patients with EGFR mutation-positive NSCLC included in the study, 34 relapsed within 3 years after resection. The median age of the relapsing cohort was 71.5 (range: 49–89) years. Most patients were nonsmokers (n = 21; 61.8%) and of female sex (n = 21; 61.8%). Most cases (n = 17; 50%) presented an exon 21 mutation, whereas 15 and four patients had an exon 19 and exon 18 mutation, respectively. Differential expression analysis revealed that circRUNX1, along with circFUT8 and circAASDH, was up-regulated in relapsing patients (p < 0.05 and >2 fold-change). A ML-based circRNA signature predictive of recurrence in patients with EGFR mutation-positive NSCLC, comprising circRUNX1, was developed. Our final model including selected 6-circRNA signature with random forest algorithm was able to classify relapsing patients with an accuracy of 83% and an area under the receiver operating characteristic curve of 0.91.RFS was significantly shorter not only for the subgroup of patients with high versus low circRUNX1 expression but also for the group classified as recurrent by the ML circRNA signature when compared with those classified as nonrecurrent. ConclusionsOur findings suggest that circRUNX1 and the presented ML-developed signature could be novel tools to predict the benefit of adjuvant EGFR tyrosine kinase inhibitors with regard to RFS in patients with EGFR-mutant NSCLC. The training and validation phases of our ML signature will be conducted including bigger independent cohorts.

565P Genome-guided targeted therapy combination improves survival in patients with advanced EGFR mutation positive NSCLC failing osimertinib

565P Genome-guided targeted therapy combination improves survival in patients with advanced EGFR mutation positive NSCLC failing osimertinib

A Phase 2 Single-Arm Study of Osimertinib for Radiotherapy-Naive Central Nervous System Metastasis NSCLC: Results for the First-Line Cohort of the OCEAN Study (LOGIK 1603/WJOG 9116L)

IntroductionOsimertinib may be effective in treating central nervous system (CNS) metastasis, but its efficacy in treating radiation therapy (RT)-naive metastasis is unclear. The OCEAN study assessed the efficacy of osimertinib against RT-naive CNS metastasis in patients previously treated (T790M cohort) and untreated patients (first-line cohort) with EGFR mutation. Here, we report the results of the first-line cohort. MethodsPreviously untreated patients with RT-naive CNS metastasis and EGFR mutation-positive NSCLC were treated with osimertinib. The brain metastasis response rate (BMRR), progression-free survival (PFS), and overall survival in the first-line cohort were secondary end points. ResultsA total of 26 patients were enrolled in the study between September 2019 and July 2020. The median age was 72.0 years with 80.8% female. There were 20 patients who had multiple CNS metastases. BMRR assessed by PAREXEL criteria was 76.9% (90% confidence interval [CI]: 63.3%–90.5%), BMRR assessed by Response Evaluation Criteria in Solid Tumors was 76.9% (95% CI: 54.0%–99.8%), and median PFS of CNS metastasis was 22.0 months (95% CI: 9.7 mo–not reached). The overall response rate was 64.0% (95% CI: 45.2%–82.8%), median PFS was 11.5 months (95% CI: 6.9 mo–not reached), and median survival time was 23.7 months (95% CI: 16.5 mo–not reached). Paronychia and increased creatinine level were the most frequent nonhematological toxicities observed in 13 patients (50%). Grade three and higher adverse events were less than 10%, and there were no treatment-related deaths. Pneumonitis was observed in five patients (19.2%). ConclusionsThese results suggest that osimertinib is effective in untreated patients with RT-naive asymptomatic CNS metastasis in a clinical practice first-line setting. Trial registrationUMIN identifier: UMIN000024218. jRCT identifier: jRCTs071180017.

1337P Real-world utilization and outcomes of dacomitinib as first-line therapy in Asian patients with advanced EGFR mutation–positive NSCLC: An interim analysis of the ARIA study

1337P Real-world utilization and outcomes of dacomitinib as first-line therapy in Asian patients with advanced EGFR mutation–positive NSCLC: An interim analysis of the ARIA study

Differential expression analysis of circRUNX1 in patients with early resected EGFR-mutant NSCLC.

8529 Background: In the ADAURA study, patients with stage IB-IIIA of resected EGFR mutated lung adenocarcinoma receiving adjuvant osimertinib had a 2-year survival of 89% versus 52% in the placebo group (p&lt;0.001), however, predictive markers of response and recurrence are still needed. Circular RNA (circRNA) is a type of RNA which forms a covalently closed continuous loop. Some circRNAs have been reported as essential for tumor cell proliferation through functions distinct from the canonical linear RNA. In this project, we studied circRNA expression levels in formalin-fixed paraffin-embedded (FFPE) lung tumor samples in order to explore potential biomarkers that could predict the benefit of adjuvant EGFR TKIs in EGFR-mutant NSCLC patients. Methods: FFPE tumor samples from patients with EGFR-mutant, stage I-IIIB NSCLC (n=79) were collected. RNA was purified using the High Pure FFPET RNA Isolation Kit (Qiagen) and quantified by Nanodrop 2000 (Thermo Scientific). A total of 250 ng of RNA were subjected to overnight hybridization and downstream nCounter processing (NanoString) following manufacturer’s instructions for our circRNA custom panel. Differential expression analysis was performed using Excel (Microsoft) and Prism GraphPad (Dotmatics) software. Results: Analysis of the 79 samples included in the study shown a cluster of 3 circRNAs significantly upregulated (p&lt;0.05 and &gt;2 fold-change) in EGFR mutation-positive NSCLC relapsing withing the 36 months after resection, including circRUNX1, circFUT8 and circAASDH. Disease-free survival (DFS) was significantly shorter for the subgroup of patients with high versus low circRUNX1 expression. Additional multivariate analysis identified circRUNX1 expression and tumor stage as the only statically significant prognostic factors (circRUNX1 hazard ratio = 4.480, confidence interval = 2.172-9.239, P &lt; 0.001; pathological stage hazard ratio = 2.237, confidence interval = 1.183- 4.231, P = 0.008). Conclusions: CircRUNX1 could be a novel biomarker to predict the benefit of adjuvant EGFR TKIs with regards to DFS in EGFR-mutant resected NSCLC patients.

Trastuzumab-Emtansine and Osimertinib Combination Therapy to Target HER2 Bypass Track Resistance in EGFR Mutation-Positive NSCLC

IntroductionEGFR tyrosine kinase inhibitor improved the survival of patients with metastatic EGFR mutation-positive (EGFRm+) NSCLC. Despite high response rates, resistance develops inevitably in every patient. In up to 13%, HER2 protein overexpression is found on progression. We hypothesized that dual blockade of EGFR and HER2 by osimertinib combined with trastuzumab-emtansine (T-DM1) could reinduce tumor responses. MethodsIn this multicenter, single-arm, phase 1-2 study (NCT03784599), patients with EGFRm+ NSCLC, progressing on osimertinib and HER2 overexpression were included. Patients were treated with T-DM1 3.6 mg/kg (intravenously) every 3 weeks and osimertinib 80 mg once a day. Primary end points were objective response rate (ORR) at 12 weeks and safety. Responses were assessed every 6 weeks (Response Evaluation Criteria in Solid Tumors 1.1). Sample size was calculated using Simon’s two-stage minimax design (H0 = 41%, H1 > 55%, 80% power, one-sided type I error 10%: a ORR 16 of 36 was needed to proceed to 58 patients). ResultsFrom January 2019 to April 2021, 27 patients were enrolled. ORR after 12 weeks of treatment was 4% (1 of 27). Median progression-free survival was 2.8 months (95% confidence interval: 1.4–4.6 mo). Most frequent treatment-related adverse events of any grade were fatigue, diarrhea, and nausea, among these, grade 3 in four patients. There were no grade 4 or 5 therapy-related adverse events. ConclusionsTRAEMOS (Trastuzumab-Emtansine and Osimertinib) is the first trial combining T-DM1 and osimertinib in patients with EGFRm+ NSCLC to target HER2 overexpression at osimertinib resistance. Safety profile was favorable compared with cytotoxic chemotherapy; but treatment revealed limited efficacy. Further clinical evaluation of this regimen is not warranted.

"Sandwich" Strategy to Intensify EGFR Blockade by Concurrent Tyrosine Kinase Inhibitor and Monoclonal Antibody Treatment in Highly Selected Patients.

EGFR TKIs are not curative, and targeted resistance inevitably results in therapeutic failure. Additionally, there are numerous uncommon EGFR mutations that are insensitive to EGFR TKIs, and there is a lack of clinical strategies to overcome these limitations. EGFR TKI and mAbs target EGFR at different sites, and a combination regimen for delaying/preventing resistance to targeted therapy or obtaining more intensive inhibition for uncommon mutations at cellular, animal and human levels has been explored. This review critically focuses on a combination strategy for uncommon EGFR mutation-positive NSCLC, and discuss the preclinical data, clinical implications, limitations and future prospects of the combination strategy.

P28-7 Short-term efficacy of osimertinib (Os) in untreated EGFR mutation-positive NSCLC: A single institution experience

The FLAURA study reported the efficacy of Os as first-line treatment for EGFR mutation-positive NSCLC (EGFRmNSCLC), and upfront Os was introduced into clinical practice in August 2018. We will discuss the short-term efficacy in practice setting.

Abstract 5353: PIK3CA and PTEN mutations as drivers of osimertinib resistance in patients with NSCLC

Abstract Osimertinib is a third-generation EGFR-TKI approved for the first-line treatment of EGFR-driven lung adenocarcinomas. High response rates to osimertinib are observed in patients with activating EGFR mutations. However, there is variability in duration of response and patients eventually develop acquired resistance.Preclinical validation of potential acquired resistance mutations identified in relapsed patients treated with osimertinib is a key challenge to develop new strategies to improve outcomes for patients with EGFR mutation positive NSCLC. Tissue and ctDNA NGS analysis from relapsed patients treated first-line with osimertinib in the FLAURA and ORCHARD trials identified PIK3CA gain of function (GOF 11%) and PTEN loss of function (LOF 5%) mutations.To test whether PIK3CA activating mutations can drive resistance to osimertinib we introduced PIK3CA activating variants (PIK3CA-H1047R and PIK3CA-E453K) or knocked-out PTEN in NSCLC lung cancer cell lines harbouring EGFR activating mutations and WT PIK3CA/PTEN using CRISPR/Cas9 technology. Our results show that PIK3CA GOF and PTEN LOF mutations conferred resistance to osimertinib in vitro. Resistance was associated with increased EC50 for osimertinib and diminished apoptotic response in NSCLC PIK3CA GOF and PTEN LOF mutant CRISPR cell lines when compared to parental cells. Protein analysis by western blot also showed an increase in the basal and osimertinib treated levels of pAKT and pS6 in PIK3CA/PTEN CRISPR engineered cell lines, indicating activation of downstream PI3K/AKT and MAPK signalling pathways in the osimertinib-resistant cells. Importantly, our in vitro experiments from multiple cell line models indicated that PIK3CA-mediated resistance to osimertinib could be partially reversed by co-treatment with AKT (capivasertib, AstraZeneca) and PI3K alpha (alpelisib, Novartis) inhibitors; PTEN-mediated resistance could be rescued by co-treatment with capivasertib and PI3K beta (AZD8186, AstraZeneca) inhibitors. We next examined the in vivo efficacy of osimertinib + AKT/PI3K inhibitors therapies in NSCLC xenograft models. Our in vivo analysis show that PIK3CA GOF CRISPR engineered cells displayed diminished response to osimertinib when implanted in mice; importantly, combination with AKT (capivasertib) or PI3K alpha (alpelisib) inhibitors enhanced response on treatment and delayed outgrowth after withdrawal treatment. In addition, we observed that combination treatment with capivasertib induced tumour stasis in a PIK3CA-E454K and two PTENloss PDX models.Altogether our in vitro and in vivo data provide evidence of PIK3CA mutants and PTEN loss-driven mechanisms of resistance to osimertinib and offer possible therapeutic combination strategies for those patients that develop resistance or experience a sub-optimal response to osimertinib through PIK3CA/PTEN mutations Citation Format: Ursula Grazini, Daniel J. O'Neill, Matthew Martin, Chintia Xu, Nicolas Floch, Paul D. Smith, Emanuela Cuomo. PIK3CA and PTEN mutations as drivers of osimertinib resistance in patients with NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5353.

Durvalumab (durva) after chemoradiotherapy (CRT) in unresectable, stage III, EGFR mutation-positive (EGFRm) NSCLC: A post hoc subgroup analysis from PACIFIC.

8541 Background: Standard of care for patients (pts) with unresectable (UR) stage III NSCLC is the ‘PACIFIC regimen’, based on data from the phase 3 placebo (pbo)-controlled trial where consolidation durva following CRT improved overall survival (OS; hazard ratio [HR], 0.68 [95% CI, 0.53, 0.87]) and progression-free survival (PFS; HR, 0.52 [95% CI 0.42, 0.65]), in an all-comer population. However, the benefit of immunotherapy (IO) in pts with EGFRm stage III NSCLC is unclear. We report a post hoc exploratory efficacy and safety analysis from 35 pts with EGFRm NSCLC from the PACIFIC trial (NCT02125461). Methods: Pts with stage III UR-NSCLC, WHO performance status (PS) 0/1 and no progression after ≥2 cycles platinum-based concurrent CRT were randomized 2:1 (1–42 days post CRT) to receive durva (10mg/kg IV q2w for up to 1 year) or pbo, stratified by age, sex, and smoking history; enrollment was not restricted by oncogenic driver gene mutation status or PD-L1 expression. Primary endpoints: PFS (BICR; RECIST v1.1) and OS; key secondary endpoints: objective response rate (ORR) and safety. Treatment effects for the EGFRm subgroup were estimated using an unstratified Cox proportional hazard model; medians were estimated using the Kaplan–Meier method. Statistical analyses were exploratory. Data cut-off (DCO) for the EGFRm subgroup efficacy analysis was 11 January 2021. Results: Of 713 pts randomized, 35 had EGFRm NSCLC based on local testing (durva n = 24, pbo n = 11). In the EGFRm subgroup, more pts in the pbo vs durva arm were male (73% vs 54%), had stage IIIA disease (64% vs 46%), PS 0 (64% vs 54%) and received pre-CRT induction chemotherapy (36% vs 8%). More pts in the durva arm were Asian (63% vs 55%) and had PD-L1 on &lt; 25% tumor cells (67% vs 36%); median age was consistent across arms. At DCO, median duration of follow-up for survival was 42.7 months (range, 3.7–74.3 months) for all randomized pts in the subgroup. Median PFS was 11.2 months (95% CI 7.3, 20.7) with durva vs 10.9 months (95% CI 1.9, not evaluable [NE]) with pbo; HR 0.91 (95% CI 0.39, 2.13). Median OS was 46.8 months (95% CI 29.9, NE) with durva vs 43.0 months (95% CI 14.9, NE) with pbo; HR 1.02 (95% CI 0.39, 2.63). ORR was 26.1% (95% CI, 10.2, 48.4) and 18.2% (95% CI 2.3, 51.8) with durva and pbo, respectively. The safety profile for durva was consistent with the overall population. In the durva and pbo subgroup arms, radiation pneumonitis was reported in 42% vs 36% of pts, and pneumonitis was reported in 17% vs 18% of pts (1 grade 3, pbo arm), respectively. Conclusions: In this post hoc exploratory analysis of 35 pts, PFS and OS outcomes with durva were similar to pbo in the EGFRm population, with wide CIs. The benefit of IO in this population remains unclear. The ongoing LAURA study (NCT03521154) is investigating the efficacy and safety of maintenance osimertinib in pts with locally advanced EGFRm stage III UR-NSCLC with no progression after CRT. Clinical trial information: NCT02125461.