EGFR-mutant Pts Research Articles

Abstract CT247: Updated efficacy and safety of anti-TROP2 ADC SKB264 (MK-2870) for previously treated advanced NSCLC in Phase 2 study

Abstract Background: TROP2 (trophoblast cell surface antigen 2) is commonly over-expressed in non-small cell lung cancer (NSCLC) and associated with poor prognosis. SKB264 (MK-2870) is a TROP2 ADC developed with a novel linker to conjugate the payload, a belotecan-derivative topoisomerase I inhibitor. The linker is affected by both extracellular pH-sensitive cleavage and intracellular enzymatic cleavage within tumor cells, which leads to efficiently release payload inside tumor cells as well as within tumor microenvironment to exert its anti-tumor effects. Here, we present the updated data from a Phase 2 expansion cohort for patients (pts) with advanced NSCLC. Methods: Pts with previously treated advanced NSCLC were enrolled to receive SKB264 at 5 mg/kg Q2W until disease progression or unacceptable toxicity (KL264-01, NCT04152499). Tumor assessment was performed every 8 weeks per RECIST v1.1 assessed by investigator. Results: As of Nov 22, 2023, 43 NSCLC pts had been enrolled. Median follow-up was 17.2 months (mo). 21 pts with EGFR wild type had received median prior 3 regimens of therapy including anti-PD-1/L1 inhibitors. 22 pts with EGFR mutant had progressed on or after TKI therapy, 50% of whom also failed at least one line of chemotherapy. Updated efficacy results are shown in the Table. Overall, 30 pts (69.8%) experienced Grade ≥3 treatment-related adverse events (TRAEs). The most common Grade ≥3 TRAEs were neutrophil count decreased (34.9%), anemia (30.2%), WBC count decreased (25.6%), stomatitis (9.3%), and rash (7.0%). No TRAEs leading to treatment discontinuation or deaths occurred. No drug-related ILD/pneumonitis was reported. Conclusions: The updated data continues to demonstrate that SKB264 monotherapy delivers promising clinical efficacy with manageable toxicity in pretreated advanced NSCLC pts. A Phase 3 global study of SKB264 in pts with 3L+ EGFR mutant NSCLC (NCT06074588) and a Phase 3 study of SKB264 in China in pts with 2L EGFR mutant NSCLC (NCT05870319) are ongoing. TABLE 1: NAND Table Clinical outcomes by EGFR mutation status Overall (N=43) EGFR mutant (N=22) EGFR wild type Total (N=21) Non-squamous (N=9) Squamous (N=12) ORR*, % 43.6% 60.0% 26.3% 22.2% 30.0% Median DoR, mo (95%CI) 9.3 (3.7, 10.3) 8.7 (3.7, 10.3) 9.6 (3.5, NE) / / Median PFS, mo (95% CI) 7.2 (5.4, 11.3) 11.5 (5.7, 12.9) 5.3 (3.5, 6.2) 5.8 (1.5, 12.1) 5.1 (1.9, 9.3) Median OS, mo (95% CI) 22.6 (13.1, NE) 22.7 (19.7, NE) 14.1 (10.7, NE) 16.2 (5.8, NE) 12.8 (3.5, NE) 12-mo OS rate, % (95% CI) 69.0% (52.7, 80.7) 81.0% (56.9, 92.4) 57.1% (33.8, 74.9) 66.7% (28.2, 87.8) 50.0% (20.8, 73.6) 18-mo OS rate, % (95% CI) 56.5% (40.1, 70.0) 76.2% (51.9, 89.3) 35.9% (16.0, 56.4) 44.4% (13.6, 71.9) 30.0% (7.7, 56.9) *Including confirmed or unconfirmed response. Based on response evaluable pts (≥1 on-study scans) with 4 pts (2 EGFR mutant pts with non-squamous histology and 2 EGFR wild type pts with squamous histology) excluded. Citation Format: Wenfeng Fang, Ying Cheng, Zhendong Chen, Wei Wang, Yongsheng Li, Yongmei Yin, Xingya Li, Huiting Xu, Guohua Yu, Yanjun Mi, Zev A. Wainberg, Jordi Rodon, Xiang Wang, Xian Wang, Xiaoqing Zhang, Xiaoping Jin, Lian Lu, Junyou Ge, Jin Li, Li Zhang. Updated efficacy and safety of anti-TROP2 ADC SKB264 (MK-2870) for previously treated advanced NSCLC in Phase 2 study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT247.

Tissue- and liquid-biopsy based NGS profiling in advanced non-small-cell lung cancer in a real-world setting: The IMMINENT study.

e21154 Background: NGS-based profiling is the current standard for the molecular characterization of advanced NSCLC (aNSCLC) in clinical practice. Here we report the results of tissue- and liquid-biopsy based NGS, using FoundationOne and FoundationLiquid CDx (FM1/FM1L), in the context of a multicenter national access program in a cohort of aNSCLC patients (pts). Methods: Genomic evaluation was performed on FFPE-tumor blocks or blood samples, using FM1 (324 genes) for tissue samples or FM1L (70 genes) for liquid biopsy. Tumor mutational burden (TMB) and microsatellite instability were also evaluated. The aim of this analysis was to investigate the real-world frequency of molecular alterations in aNSCLC and their correlation with patients’ clinical and pathological characteristics. Results: Overall, 232 aNSCLC pts from 11 different institutions were gathered [median age 63 years, never/former or current smokers 29/66%, Performance Status 0-1 93%, adenocarcinoma/squamous 79/13%, metastasis at diagnosis 70%]. 138 pts (59.5%) underwent FM1 and 94 (40.5%) FM1L analyses. Alterations were found in 170 different genes. Median number of mutated genes per sample was 4 (IQ 3-6) in FM1 cohort and 2 (IQ 1-3) in FM1L cohort. In 13 FM1L samples (5.6%) no genetic alterations were detected. In unselected pts, TP53 (57.8%), KRAS (22%), CDKN2A/B (19%) and STK11 (17.2%) alterations were among the most frequently detected. Percentages of ALK, HER2, RET, MET, BRAF, NTRK and ROS1 alterations were 4.3, 4.3, 3.4, 3.0, 2.6, 1.3, 0.9, respectively. Among EGFR-mutant pts (15.1%), in both FM1 and FM1L cohorts, ex19del (31.3/35.7%), L858R (12.5/14.3%) and T790M (0/14.3%) were the most frequently detected. Among KRAS-mutant pts, G12C was the mutation most frequently detected (37%). Alterations in KEAP1 were significantly associated with STK11, SMARCA4 and KRAS alterations. Significant associations between TP53 and RB1 alterations were also detected. Median TMB was 6 (0-100) and was significantly higher in current/former smokers. Median OS was 19.6 months (IQ 6.9-36.1), and significantly lower in pts harboring ≥3 gene mutations.25 pts (10.8%) received target therapy on the basis of molecular profiling with FM1/FM1L. In this subgroup, EGFR was the most frequently actionable gene alteration detected (9), followed by RET (4), ALK (3), KRAS (2), MET (2), NTRK (2), BRAF (1), BRCA (1) and HER2 (1). Conclusions: This analysis confirms that NGS-based molecular profiling (on either tissue or blood samples) of aNSCLC provides important prognostic and predictive information, possibly increasing treatment opportunities. Further analyses will focus on actionable alterations in potentially clinically relevant genes outside “the usual suspects”. In the awareness of the urgent need for real world data and to implement NGS, ATLAS ( https://biomarkersatlas.com/ ) will certainly be a fundamental tool.

P1.01-50 Impact of Concomitant HER2 Alterations in Mediating Clinical Outcomes of EGFR-Mutant Patients to Different Generation of EGFR-TKIs

The 2nd generation EGFR-TKI are selective and potent irreversible pan-HER inhibitors. Given their effect on HER2 besides EGFR, we investigated the role of HER2 co-alterations in mediating the clinical outcomes of EGFR-mutant non-small cell lung cancers to 2nd generation or other generation EGFR-TKIs. Plasma/tissue samples from advanced NSCLC before and after 1L EGFR-TKI treatment were sequenced using 168-/520-cancer-related gene panels, respectively. Clinical records of 94 EGFR-mutant pts (92 adenocarcinomas and 2 adenosquamous cell carcinomas) after 1st/3rd (n=73) or 2nd generation (afatinib, n=16; dacomitinib, n=5) EGFR-TKI treatment were collected for clinical outcomes evaluation. Event-time distributions were estimated using Kaplan-Meier and compared with long-rank test. Among the 94 pts identified as EGFR-positive at baseline, 8 (8.5%) had concurrent HER2 gain-of-function alterations (amplification or active mutation). Survival analysis showed that for those with concomitant EGFR and HER2 alterations at baseline, pts achieved favorable PFS (23.2 vs 5.6 months, p=0.04) to 2nd generation (n=2) than to 1st/3rd generation EGFR-TKI (n=6) as 1L treatment. And for those receiving 1L 1st/3rd generation EGFR-TKI (n=73), the presence of baseline HER2 alterations (n=6) was associated with shorter PFS (5.6 vs 9.8 months, p=0.16) and OS (15.7 vs 21.0 months, p=0.06) than absence of HER2 (n=67), although the difference was not significant due to a small sample size. In addition, we found all the samples (n=21) obtained from pts after 2nd generation EGFR-TKI resistance were HER2-negative, but pts progressed on 1st or 3rd generation EGFR-TKI with HER2 as the only resistance mechanism were observed in our study cohort. Our findings suggested that, for EGFR-mutant pts combined with HER2 alterations at baseline or those resistant to 1L treatment of 1st/3rd EGFR-TKI due to HER2 alterations only, 2nd EGFR-TKI might be a better choice. Our findings suggested that, for EGFR-mutant pts combined with HER2 alterations at baseline or those resistant to 1L treatment of 1st/3rd EGFR-TKI due to HER2 alterations only, 2nd EGFR-TKI might be a better choice.

1992P - Prognostic role of CD73 in metastatic non small cell lung cancer according to the presence of driver alterations

1992P - Prognostic role of CD73 in metastatic non small cell lung cancer according to the presence of driver alterations

Abstract 3411: Genomic profiling of non-small cell lung cancer in Xuanwei, Yunnan Province

Abstract Background Xuanwei, a rural county, is located in the northeast of Yunnan Province, China. According to a national retrospective survey on cancer mortality during 1973-1975, the highest mortality rate of lung cancer in Xuanwei was 5.3 times higher than that in rural areas nationwide. Age standardized mortality rates (ASMR) of lung cancer were 23.14/105 and 4.34/105 in Xuanwei and rural areas in China respectively. Characterization of genomic alterations(GAs) that drive patients (pts) disease development is critical in cancer management. However, the comprehensive genomic features of pts with non-small cell lung cancer (NSCLC) in Xuanwei have not been well understood. Methods: Next generation sequencing (NGS) targeting 37 lung cancer related driver genes was performed on FFPE and matched blood samples that collected from 85 NSCLC pts in Xuanwei. The pts included 50 males (59%) and 35 females (41%) with a median age of 54 years (range 36-78). GAs including single nucleotide variations (SNV), short and long insertions and deletions (Indel), copy number variations (CNV), and gene rearrangements were analyzed. Results: The histological subtypes of our cohort included LUAD(n=68, 80%), LUSC(n=9, 10.6%) and others(n=8, 9.4%).The most common GAs detected were TP53 (56%), EGFR (46%), KRAS mutation (25%), APC (8%), PIK3CA (8%), CDKN2A (7%), PTEN (6%), ALK (5%), CDK4 (5%), MTOR (5%), NTRK3 (5%) and PDGFRA (5%). In total, 74.1% of the pts had one or more actionable GAs. PI3K/mTOR pathway alterations including PTEN, MTOR,TSC1/2 and PIK3CA mutations were detected in 23.5% of the pts. Compared with OrigiMed unpublished data from larger Chinese NSCLC pts (EGFR 47.6%, ALK fusion 8.3%, KRAS 12.3%, n=1200), we identified similar frequency of EGFR mutation, while we found significant higher frequency of KRAS mutation(25%, n=85, P <0.001) and lower incidence of ALK fusion (1.2%, n=85, P =0.025) in Xuanwei cohort. Comparing to OrigiMed unpublished data(as above), comprehensive genomic profiling (CGP) identified unique EGFR mutation profile in Xuanwei cohort that G719X occurred much more frequently (43.6% vs. 5.15%, P <0.001). 43.6%(17/39) EGFR-mutant pts harbored the uncommon mutation G719X, which could be identified alone (8%) or combined with other EGFR mutations (35.6%), the distribution of combined G719X mutations are G719X+S768I (15.4%),G719X+E709A(5.1%),G719X+G779C(5.1%),G719X+L838V(2.5%),G719X+L861Q(2.5%),G719X+S768I+N1107D(2.5%),G719X+T790M+V651L(2.5%). Conclusions: Comparing to the large cohort of Chinese pts with NSCLC, we identified higher mutation frequency of KRAS (P <0.001) and lower frequency of ALK fusion (P =0.025) in Xuanwei cohort. EGFR uncommon mutation G719X were identified in 43.6% of EGFR-mutant pts, but only accounted for 5.15% of EGFR-mutant pts in large Chinese NSCLC cohort. Therefore, the NGS based target sequencing assay revealed a unique pattern of driver gene mutations in Xuanwei cohort. Citation Format: Gang Guo, Tao Shou, Gaofeng Li, Hao Peng, Juan Zhao, Honglin Guo, Lin Zhang, Yunfei Shi. Genomic profiling of non-small cell lung cancer in Xuanwei, Yunnan Province [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3411.

Clonal evolution and osimertinib resistance mechanisms identified by whole exome and transcriptome sequencing in EGFR mutant NSCLC.

9049 Background: Osimertinib, a 3rd generation EGFR TKI, has been approved for treatment naïve patients (pts) with metastatic EGFR mutant NSCLC. Mechanisms of resistance to osimertinib are emerging from limited studies using targeted sequencing platforms. Methods: We performed whole exome (WES) and RNA-sequencing of osimertinib resistant tumors of EGFR-mutant NSCLC pts treated in a prospective clinical trial (NCT02759835). Treatment naïve EGFR mutant pts or pts with T790M-positive NSCLC after EGFR-TKI treatment receive osimertinib. Upon progression, pts with ≤5 progressing sites undergo local ablative therapy (LAT; surgery, radiation, RFA) and resume osimertinib. We analyzed paired pre-treatment and post-progression tumors in 10 patients and post-progression tumors in 3 additional patients and investigated intra- and inter-metastatic tumor heterogeneity using tumors procured from LAT surgeries and autopsies. Results: Acquired, focal copy number amplifications (CNA) of oncogenes occurred in the majority of patients (54%, n = 7/13) whereas acquired osimertinib resistance mutation EGFR C797S was less common (15%, n = 2/13). Early progression on osimertinib ( < 12 months PFS) in treatment naïve pts was associated with acquired, focal CNA. Despite pre-existing EGFR amplification, further amplification of the mutant allele of EGFR was the most common focal CNA (33%, n = 3/9). Other oncogenes amplified in resistant tumors include MET, KRAS, ERBB2 and YES1. CD274 (PD-L1) amplification occurred as the only putative mechanism of resistance in a pt without prior EGFR-TKI treatment. Using RNA-seq, we identified a pt who retained NSCLC histology, but upregulated genes associated with neuroendocrine differentiation upon osimertinib resistance. Clonal evolutionary analysis using WES of prospectively collected sensitive and resistant tumor tissue, including at autopsy is underway. Conclusions: Unbiased WES and transcriptome sequencing revealed heterogeneity, clonal evolution and novel osimertinib resistance mechanisms. Majority of pts had two or more resistance mechanisms suggesting the requirement of combination therapies to overcome resistance. Clinical trial information: NCT02759835.

Osimertinib with chemotherapy for EGFR-mutant NSCLC at progression: Safety profile and survival analysis.

9083 Background: First generation EGFR TKIs are well tolerated with chemotherapy (chemo), and have evidence of improved efficacy in EGFR-mutant NSCLC. Osimertinib (osi) is a 3rd-generation EGFR TKI with improved T790M and CNS activity. Safety and outcome data combining osi and concurrent chemo are limited. Methods: EGFR-mutant pts who received osi with chemo between 12/2015 and 8/2018 were retrospectively identified at two institutions. Pt demographics, toxicities and outcomes were collected by chart review. Results: 35 pts received osi + chemo, 29/35 pts had CNS mets. 16/35 had > = one prior chemo and/or immunotherapy, 34/35 previously received a 1st/2nd gen EGFR TKI (25/35 T790M+ at progression), and all 35 had prior progression on osi. 47 osi + chemo regimens were abstracted: carboplatin/pemetrexed+/-bevacizumab (n = 17), cisplatin/pem (1), carbo/taxane (2), pem+/-bev (7), taxane (7), gemcitabine (8), irinotecan (3), vinorelbine (2); 32/35 pts had platinum. Osi was dosed at 80 mg QD (32), 160 mg QD (2), or 80mg QOD (1). Toxicities (table) occasionally led to treatment delay (n = 5), osi dose-reduction (2) and discontinuation (3). Median overall survival (mOS) from metastatic diagnosis was 48.4 mo (95% CI 30.7-NR); mOS from first osi was 19.6 mo (95% CI 16.1-32.6). Median duration of treatment (mDOT) for first regimen of chemo + osi was 5.3 mo (95% CI 4.1-9.5); stratifying by chemo, mDOT for platinum doublet + osi was 6.1 mo (95% CI 4.7-NR) and mDOT for osi + single agent was 3.2 mo (95% CI 2.4-5.3). In the 29 pts with brain mets receiving their first regimen of osi + chemo, 6 had CNS progression but only 2 required radiation at progression. Conclusions: Osimertinib is tolerable in combination with many standard chemo regimens for EGFR-mutant NSCLC. mDOT for platinum doublet and single agent are similar to historical controls, but CNS disease control appears better than expected for chemotherapy alone. Adding chemotherapy at the time of progression on osimertinib may be considered for selected pts, particularly those with known CNS mets. [Table: see text]

A prospective evaluation of cell free DNA (cfDNA) genotyping and circulating tumor cells (CTC) in EGFR mutant NSCLC patients (pts) treated with erlotinib.

11068 Background: Genotype directed therapy is now standard of care for advanced NSCLC pts. However, adequate tumor tissue for comprehensive genotyping remains a challenge. Recent research suggests that CTC capture or cfDNA analysis allows for non-invasive diagnosis and monitoring of treatment. This prospective trial was designed to quantify the predictive value of CTC and cfDNA analyses of EGFR-mutant NSCLC pts treated with first-line erlotinib. Methods: TKI naive EGFR mutant NSCLC pts were enrolled in a phase II trial of erlotinib treatment. Paired blood for cfDNA and CTC analysis was collected at baseline prior to therapy and every 2 months during follow ups. Plasma genotyping was performed by ddPCR for EGFR19del, L858R, T790M while CTCs were isolated by CellSearch and analyzed by IF and MET-FISH. Repeat biopsies at progression were performed when feasible. Results: Between 2/10 and 1/15, 60 EGFRmutant pts (L858R:17, 19del:38, other:5) were enrolled. As of 1/15, 44 patients have discontinued therapy (3...

Retrospective chart review of end-of-life (EOL) care in patients with metastatic lung cancer harboring EGFR mutations.

126 Background: Metastatic lung cancer is the leading cause of cancer-related death in the US. In the last decade, however, patients (pts) with EGFR mutations have benefitted from improved outcomes with EGFR-directed targeted therapy. We hypothesized that this improvement might impact EOL care. The objective of this chart review was to describe the care of EGFR mutant pts with attention to EOL care, health care utilization, and palliative care use. Methods: With IRB approval, we retrospectively reviewed medical records of pts at our center diagnosed with advanced EGFR-mutant lung cancer from January 2009 to June 2012. We limited the review to pts who had at least one cancer therapy at MGH, and to those who died by June 2014. Results: 44 pts were included. 30 pts (68%) were female. 32 pts (73%) received cancer-directed therapy within 30 days of death. Of these, 30 pts (68%) received oral chemotherapy and 5 (11%) received IV chemotherapy. 30 pts (68%) were hospitalized within 30 days of death. Over their entire disease course, the median number of hospitalizations was 2 (0-8), and the median number of total inpatient days was 12 (0-88). 21 pts (48%) had a palliative care outpatient visit and 34 (77%) had an inpatient palliative care consult at some point during their care. 24 pts (54%) enrolled on hospice prior to death, 15 (34%) were never on hospice, and the hospice status of 5 (11%) was unknown. Of the 39 pts with known hospice status, median length of stay was 6 days (0-206). 23 pts (52%) died at home with hospice or in an inpatient hospice, 16 (36%) died in the hospital, 2 (4%) died at home without hospice, and the location of death was unknown for 3 (7%). Conclusions: Pts with EGFR mutations had high rates of hospitalization and chemotherapy use in the last month of life, and many died in the hospital. Palliative care utilization was high, but it is unclear how this affected EOL care. Designing innovative care models to support this unique population and understand EOL decision-making should be a priority.

Adaptive cell plasticity in autocrine TGFβ2 coordinated transcriptome-metabolome reprogramming of EGFR-mutant lung cancer in precision therapy escape.

e19043 Background: Precision therapy for advanced NSCLC with EGFR mutations is the current standard-of-care. Emergence of acquired resistance to therapy invariably occurs despite effective initial response. Classical rebiopsy studies of EGFR-mutant pts at progression have identified diverse resistance mechanisms involving T790M-EGFR, METactivation and AXL upregulation. Our studies focus on tumor cells adaptation early during therapy to map the initial course of therapeutic resistance evolution. Methods: Drug-sensitive model studies were performed usingHCC827 and PC-9 NSCLC cells under erlotinib, and H1975 cells under CL-387,785 inhibition. Affymetrix microarray profiling was performed at 0h, 8h, 9d and 9d TKI followed by 7d drug-washout. Both in vitro and in vivo xenograft analyses were conducted. Mass-spectrometry based metabolomics profiling was also conducted. Results: We identified an early adaptive drug escape in EGFR-mutant cells that emerged as early as 9 days on therapy. The prosurvival cell state...

Thymidylate synthase (TS) polymorphisms (Pol) in buffy coat-derived genomic DNA as a clinical outcome predictor in non-Asian stage III/IV non-small cell lung cancer (NSCLC) patients (pts) receiving pemetrexed (Pem).

e19112 Background: TS is the main biological target of the antifolate Pem. Some TS Pol may confer a short survival and a poor response to antifolate-treated colo-rectal cancer pts. Whether TS genotype has an independent prognostic/predictive impact on non-Asian advanced NSCLC pts treated with Pem is unknown. Methods: Twenty-five non-Asian advanced NSCLC pts treated with Pem-based regimens (1st, 2nd or 3rd line) were included. Genomic DNA was isolated from periferal blood prior to treatment. The variable number of tandem repeat (VNTR) Pol, the G>C single nucleotide Pol (SNP) and the TS 6-bp insertion/deletion (6/6) in the 3' untranslated region (UTR) Pol were analyzed and correlated with response rate (RR), progression-free survival (PFS), overall-survival (OS) and toxicity (Tx). Results: Regarding the VNTR Pol, most of the pts showed 2R/2R or 3R/2R Pol (17 pts; 68%), and 8 pts (32%) showed 3R/3R or 3R/4R Pol. A SNP (G>C) in VNTR was observed in 18 pts (72%). The Pol found in the 3´UTR region were +6/+6 in 12 pts (48%), +6/-6 in 11 pts (44%) and -6/-6 in 2 pts (8%). In the subgroup of T3-T4 pts, there was a higher RR among those showing 3R/3R Pol than those with 2R/2R Pol (100% vs 83.8%; p=0.029). The genotype +6/+6 predicted a higher RR among active/former smokers (A/FS) compared to +6/-6 (100% vs 37.5%; p=0.026). A 3R/3R Pol followed by 2R/2R and 2R/3R Pol predicted a superior RR in pts with EGFR mutations (p=0.018). Overall, a trend towards a better PFS in pts showing 2R/2R Pol was found (p=0.076). The cohort’s median overall survival (OS) was not reached during follow-up. The most frequent Tx was grade (G)1 anemia (28%) and nausea (20%) and G2 leucopenia (40%). G3-4 anemia (4%), leucopenia (16%), neutropenia (4%), astenia (8%) and dyspnea (4%) were uncommon but more frequent in pts with 2R/2R Pol (p=0.545). Conclusions: In this cohort of NSCLC pts 3R/3R Pol among T3-T4 pts and EGFR mutant pts and +6/-6 bp among A/FS significantly predicted a higher RR to Pem and may aid in treatment selection. Tx was not significantly correlated with a specific TS genotype. These interesting preliminary data warrant further validation in larger series.

1339 - Impact of EGFR Mutation Status on Clinical Benefit from BIBW 2992 in Patients (PTS) with Advanced Non-Small Cell Lung Cancer (NSCLC) Progressing After Chemotherapy (CTX) and Erlotinib (E) or Gefitinib (G) – A Single Center Experience

ABSTRACT Background The reversible EGFR tyrosine kinase inhibitors E and G are effective treatments for advanced NSCLC, but most pts acquire resistance. Currently, the benefit from sustained EGFR blockade during subsequent salvage therapy is unclear. LUX-Lung 5 is an international, multicenter phase III trial studying the efficacy of BIBW2992 (Afatinib®, A), an irreversible erbB family blocker, in NSCLC pts progressing after treatment with ctx and E or G irrespective of their EGFR mutation status. Here we report the outcome of NSCLC pts treated within LUX-Lung 5 at a single center in relation to EGFR and KRAS mutation status. Methods Pts with stage IV (UICC 7) NSCLC progressing after ctx and E or G were enrolled into LUX-Lung 5. In part A of the study pts received A (starting dose 50 mg/d) until progression. In part B pts with clinical benefit ≥12 wks were randomized between A plus weekly paclitaxel vs investigator's choice mono ctx. Following microdissection, tumor DNA was extracted and analyzed by PCR and Sanger sequencing. Results Between May 2010 and February 2011 39 pts (20 f, 19 m; median age 61 y, 38-83 y) were enrolled at the West German Cancer Center. Median number of pretreatments was 3 (1-8) including E or G. So far, tumor biopsies were retrieved from 25 pts (64%). Somatic EGFR mutations were detected in 11 pts (44% of analyzed tumors, 28% of entire cohort), whereas 14 pts (56%/36%) exhibited EGFR wild type (wt) sequences. EGFR mutation status remains unknown in 14 pts (36%). KRAS mutation analysis was performed in 20 pts (51% of entire cohort) and 4 mutations were observed (20%/10%), 3 in EGFR wt and one in an EGFR mutant tumor. Median survival time from initiation of A was 432 d in EGFR mutant pts, 189 d in EGFR wt pts, and 255 d in KRAS mutant pts. Median survival time of pts with unknown EGFR mutation status was 191 d. Safety of A was manageable. Conclusions A can achieve disease control in heavily pretreated NSCLC pts. Pts with EGFR mutant tumors experience prolonged survival as compared to EGFR wt tumors (HR 0.29; 95% CI 0.07–0.64; p = 0.0058). This argues for sustained tumor dependency on EGFR signaling despite progression after E or G. Disclosure J. Kohler: J. Kohler received financial support from Boehringer Ingelheim for writing a review article. T.C. Gauler: T.C. Gauler is principle investigator of the BI1200.43 trial testing Afatinib in HNSCC. D. Theegarten: D. Theegarten is member of the Lilly Advisory Board. W. Eberhardt: W. Eberhardt received honoraries for advisory board functions from Boehringer Ingelheim, Astra Zeneca, Roche, OSi Pharmaceuticals, Pfizer and honoraries for lectures from Boehringer Ingelheim, Astra Zeneca, Roche and Pfizer. M. Schuler: M. Schuler received research funding from Boehringer Ingelheim and travel support from Lilly. All other authors have declared no conflicts of interest.

Expression of folate pathway regulators and pemetrexed (pem) activity in patients (pts) with advanced non-small cell lung cancer (NSCLC).

7585 Background: Thymidylate synthase (TS) expression has been reported to predict pem activity in pts with advanced NSCLC. Besides TS, pem inhibits multiple enzymes of the folate pathway including dihydrofolate reductase (DHFR), glycinamide ribonucleotide formyltransferase (GART) and aminoimidazole carboxamide ribonucleotide formyltransferase (AICAR). Aim of present study was to investigate whether these or other biomarkers influence pem activity in NSCLC pts. Methods: Advanced pretreated NSCLC pts who received at least two cycles of single agent pem were considered eligible if they had available tumor tissue to assess at least one of the proposed biomarkers. TS, DHFR, GART and AICAR protein expression was assessed by immunohistochemistry (IHC) in FFPE tumor samples. Pts were grouped as IHC+ and IHC– according to staining intensity. Additionally, presence of EGFR and KRAS mutations was investigated. Results: Ninety-six pts were included in the study. The majority of subjects was male (72%), smokers (93%), with adenocarcinoma (72%). Response rate (RR), disease control rate (DCR), progression-free survival (PFS) and overall survival (OS) were 12%, 47%, 2.3 and 9.5 months, respectively. Most pts resulted TS-(72%), AICAR-(82%), DHFR+ (68%), GART- (61%). EGFR and KRAS mutations were identified in 15% and 25% of assessable cases. None of the biomarkers was significantly associated with pts characteristics (gender, histology, smoking status), nor with RR or DCR. GART- pts experienced longer PFS when compared with the GART+ group (HR 0.56, p=.052), while no difference was observed according to TS, DHFR and AICAR status. A significantly longer OS was observed for TS- (HR 0.52, p=.012), GART- (HR 0.50, p=.037) and AICAR- (HR 0.40, p=.028) pts. No significant difference in the distribution of EGFR mutant pts receiving EGFR TKIs after pem failure was observed between IHC+ and IHC- groups. Conclusions: Low TS, GART and AICAR protein expression predicts significantly prolonged survival in single agent pem-treated pts with advanced NSCLC. The lack of PFS difference according to TS and AICAR status suggests prognostic rather than predictive relevance for these biomarkers.

Mutations of EGFR, K-ras, and EML-4ALK genes in resected lung adenocarcinoma and their clinical significance.

7033 Background: Mutations of EGFR, K-ras and EML4-ALK are an early event during oncogenesis of NSCLC. This study retrospectively assessed the mutations of EGFR, K-ras, and EML4-ALK and their clinical significance in resected adenocacinomas. Methods: A total of 354 patients with resected lung adenocarcinomas were retrospectively included. The mutations of EGFR (exons 19 and 21) and K-ras were determined using PCR-based fragment analysis and sequencing, and the inversion of EML4-ALK was examined using multiplex RT-PCR. The DFS for the prognostic value and the OS for the predictive value of treatment after recurrence were evaluated. Results: Mutations of EGFR and K-ras were detected in 149 (41.1%) and 18 (5.1%) of 354 tumors, respectively. The inversion of EML4-ALK was detected in 6 (7.5%) of 80 tumors. The incidence of EGFR mutations was significantly higher in females than males (52% vs. 33%, p<0.01), and in non-smokers than smokers (50% vs. 34%, p<0.01). There was no significant difference in the DFS between the mutation and wild-type groups in EGFR and K-ras. The median DFS in K-ras mutant group was 25 months which was inferior to that in EGFR-mutant group (not reached). The OS was significantly longer in pts with EGFR-mutations than in pts without EGFR-mutation (5-year survival: 82.8% vs. 67.1%, p<0.01). Fifty-six of 102 pts with recurrent disease after surgery were treated with EGFR-TKI and 46 pts were treated with other anticancer drugs. The EGFR-mutant pts (n=32) treated with EGFR-TKI had better prognosis than the EGFR-wild pts (n=24; MST after recurrence: 53 vs. 27 months, p<0.001). There was no difference in OS between EGFR mutation positive and negative groups treated without EGFR-TKI. K-ras mutations were not associated with OS. Three of 6 pts with inversion of EML4-ALK had recurrent disease and were still alive with treatment, however, the evaluation of the prognostic value was difficult because of the small number of pts with inversion. Conclusions: The mutation of EGFR was not a prognostic factor but was a predictive factor for EGFR-TKI treatment in pts with adenocarcinoma of the lung that underwent surgery. The mutation of K-ras might be poor prognostic factor.

SNaPshot multigene assay to detect mechanisms of acquired resistance to EGFR tyrosine kinase inhibitors (TKIs).

7554 Background: NSCLCs harboring activating EGFR mutations often respond to EGFR TKIs, but drug resistance invariably occurs, usually after 9-12 months. Although two validated resistance mechanisms include T790M (50%) and MET amplification (10-15%), the mechanisms of drug resistance (MODR) in the remaining 35-40% of pts remain unknown. We recently implemented an innovative multiplexed PCR-based assay (SNaPshot) to genotype cancer pts more comprehensively. SNaPshot is performed in a CLIA-certified lab with tumor DNA from paraffin-embedded samples; it tests for common mutations in 13 key oncogenes such as EGFR, KRAS, PIK3CA, BRAF, and TP53. We examined SNaPshot results in EGFR mutant cancers with acquired TKI-resistance. Methods: We reviewed all NSCLC samples sent for prospective SNaPshot analysis from 03/09 to determine the range of tumor genotypes. A simultaneous chart review identified EGFR mutant pts undergoing repeat biopsy after the development of TKI-resistance in which a corresponding pre-treatment tumor sample was available for SNaPshot analysis and MET FISH testing. Results: A total of 271 patients with NSCLC underwent SNaPshot testing between 03/09 and 11/09; 164 (61%) were found to have at least one mutation. We identified 27 EGFR mutant pts who developed TKI-resistance and had paired samples available. SNaPshot results are summarized in the Table. Interestingly, 3 pts demonstrated a major histological change from NSCLC to SCLC in the TKI-resistant biopsy (confirmed by IHC), while maintaining the original EGFR mutation. Conclusions: Here we introduce SNaPshot as a comprehensive tumor genotyping assay that is valuable for examining MODR in the clinic. Among 27 EGFR mutant pts with TKI-resistance, T790M was found in 48% and MET amplification in 4%. Notably, 1 pt acquired a PIK3CA mutation, which has been described as a MODR in vitro. Three pts experienced a fundamental transformation from NSCLC to SCLC harboring the same EGFR mutation. Investigation into the significance of the SCLC evolution and the remaining pts without identified MODR is ongoing. Observed resistance mechanisms Number Total pts 27 T790M (2 T790M + TP53) 13 MET amplification 1 PIK3CA 1 No identified mutations 12 Author Disclosure Employment or Leadership Position Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Gatekeeper Biogen Idec, Bristol-Myers Squibb, Daiichi Sankyo, GlaxoSmithKline, MedImmune, Millennium, Pfizer, Roche, Schering-Plough, Telik Novartis I participated in the development of the SNaPshot assay, which is the subject of a patent application and licensing discussions.