Co-occurrence of targetable mutations in Non-small cell lung cancer (NSCLC) patients harboring MAP2K1 mutations

BACKGROUND

MAP2K1 mutations are rare in non-small cell lung cancer (NSCLC) and considered to be mutually exclusive from known driver mutations. Activation of the MEK1-cascade is considered pivotal in resistance to targeted therapy approaches, and MAP2K1 K57 N mutation could be linked to resistance in preclinical models. We set out this study to detect MAP2K1 mutations and potentially targetable co-mutations using a molecular multiplex approach.

METHODS

Between 2012 and 2018, we routinely analyzed 14.512 NSCLC patients with two next-generation sequencing (NGS) panels. In a subset of patients, fluorescence in-situ hybridization was performed to detect rearrangements or amplifications. We assessed clinical parameters and co-occurring mutations and compared treatment outcomes of different forms of systemic therapy.

RESULTS

We identified 66 (0.5%) patients with MAP2K1 mutations. Both adenocarcinoma (n = 62) and squamous cell carcinoma (n = 4) histology. The presence of the mutations was linked to smoking, and transversions were more common than transitions. K57 N was the most frequent MAP2K1 mutation (n = 25). Additional mutations were found in 57 patients (86.4%). Mutations of TP53 were detected in 33 patients, followed by KEAP1 mutations in 28.1%. 24 patients (36.4%) had either MAP2K1-only or a co-occurring aberration considered targetable, including EGFR mutations, a BRAF V600E mutation and ROS1 rearrangements. Outcome analyses revealed a trend toward benefit from pemetrexed treatment.

CONCLUSION

Our analysis shows that MAP2K1-mutated NSCLC patients might frequently present with potentially targetable aberrations. Their role in providing resistance in these subtypes and the possible therapeutic opportunities justify further analyses of this rare NSCLC subgroup.

Phase I experience with rogaratinib in patients (pts) with urothelial carcinoma (UC) selected based on FGFR mRNA overexpression

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Background: Aberrant activation of the fibroblast growth factor receptor (FGFR) pathway is implicated in many cancers, including UC. In a recent Phase I dose-escalation study, rogaratinib, an oral pan-FGFR1-4 inhibitor, demonstrated favorable efficacy and safety in pts with solid cancers selected based on FGFR1-3 mRNA overexpression. We report results from the Phase I expansion cohort with rogaratinib in pts with UC selected by FGFR1-3 mRNA overexpression and/or FGFR3-activating mutations (NCT01976741). Methods: Pts with advanced/metastatic UC were screened for FGFR1-3 mRNA overexpression using RNA in situ hybridization (RNAscope) and NanoString assay in fresh or archival tumor samples. Pts received rogaratinib 800 mg po BID continuously. Tumor response and safety were assessed. Results: 74 pts with UC were treated with rogaratinib; 73.0% were male, median age was 66 years (range 45-85), and 93.2% had stage IV disease. Rogaratinib was well tolerated, with adverse events being mostly mild or moderate. The most common treatment-emergent adverse events (TEAEs) are shown in the Table. The most common drug-related TEAEs (any grade) were diarrhea (52.7%), increased blood phosphorus (41.9%), and decreased appetite and dry mouth (31.1% each). No ocular toxicities were reported. Increased blood creatinine and acute kidney injury (AKI), regardless of relatedness, were reported in 16.2% and 2.7% of pts, respectively; 1 case of AKI was confirmed as acute tubular necrosis. Of 72 evaluable pts, 15 (20.8%) achieved an objective response; complete and partial responses were observed in 1 (1.4%) and 14 (19.4%) pts, respectively. Stable disease was achieved by 34 pts (47.2%), with a disease control rate of 68.1%. Conclusions: Rogaratinib demonstrated a favorable safety and efficacy profile in pts with tumor FGFR1-3 mRNA-positive UC. TEAEs observed in >25% of pts. Clinical trial information: NCT01976741. [Table: see text]

Impact of TP53 mutation status on systemic treatment outcome in ALK-rearranged non-small-cell lung cancer

Background

We analyzed whether co-occurring mutations influence the outcome of systemic therapy in ALK-rearranged non-small-cell lung cancer (NSCLC).

Patients and methods

ALK-rearranged stage IIIB/IV NSCLC patients were analyzed with next-generation sequencing and fluorescence in situ hybridization analyses on a centralized diagnostic platform. Median progression-free survival (PFS) and overall survival (OS) were determined in the total cohort and in treatment-related sub-cohorts. Cox regression analyses were carried out to exclude confounders.

Results

Among 216 patients with ALK-rearranged NSCLC, the frequency of pathogenic TP53 mutations was 23.8%, while other co-occurring mutations were rare events. In ALK/TP53 co-mutated patients, median PFS and OS were significantly lower compared with TP53 wildtype patients [PFS 3.9 months (95% CI: 2.4–5.6) versus 10.3 months (95% CI: 8.6–12.0), P < 0.001; OS 15.0 months (95% CI: 5.0–24.9) versus 50.0 months (95% CI: 22.9–77.1), P = 0.002]. This difference was confirmed in all treatment-related subgroups including chemotherapy only [PFS first-line chemotherapy 2.6 months (95% CI: 1.3–4.1) versus 6.2 months (95% CI: 1.8–10.5), P = 0.021; OS 2.0 months (95% CI: 0.0–4.6) versus 9.0 months (95% CI: 6.1–11.9), P = 0.035], crizotinib plus chemotherapy [PFS crizotinib 5.0 months (95% CI: 2.9–7.2) versus 14.0 months (95% CI: 8.0–20.1), P < 0.001; OS 17.0 months (95% CI: 6.7–27.3) versus not reached, P = 0.049] and crizotinib followed by next-generation ALK-inhibitor [PFS next-generation inhibitor 5.4 months (95% CI: 0.1–10.7) versus 9.9 months (95% CI: 6.4–13.5), P = 0.039; OS 7.0 months versus 50.0 months (95% CI: not reached), P = 0.001).

Conclusions

In ALK-rearranged NSCLC co-occurring TP53 mutations predict an unfavorable outcome of systemic therapy. Our observations encourage future research to understand the underlying molecular mechanisms and to improve treatment outcome of the ALK/TP53 co-mutated subgroup.

Overcoming acquired osimertinib-resistance in EGFR-mutant advanced non-small lung cancer mediated by activating BRAF V600E mutation

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Background: There is growing insight in the mechanisms underlying resistance to the 3rdgeneration EGFR inhibitor osimertinib. Unlike resistance to 1stgeneration inhibitors, these mechanisms not necessarily lead to sequential targeted therapy approaches. Here we report on the treatment of two patients with acquired resistance to osimertinib with a new detected BRAF V600E mutation as resistance mechanism. Methods: We identified two patients with EGFR-T790M-mutant advanced NSCLC with progression on osimertinib and detection of a new BRAFV600E mutation in a tumor rebiopsy by next-generation sequencing (NGS). No other known resistance mechanism beside T790M loss in one patient was found. Osimertinib was discontinued and BRAF-targeted combination therapy with dabrafenib and trametinib at standard dose was initiated. We monitored the clinical course with sequential 18F-2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) / computed tomography (CT) assessing maximum standard uptake value (SUVmax), sequencing based liquid biopsies and tumor marker assessment. Results: Patient (1) with EGFR del19 (E746_A750del), preserved T790M mutation and acquired BRAF V600E mutation showed reduction in FDG uptake of 18% after 2 weeks of dabrafenib/trametinib that demonstrated a slight increase of 12% in a FDG-PET/CT scan 4 weeks thereafter and combination treatment has been continued. Patient (2) with EGFR del19 (E746_A750del), T790M loss and new BRAF V600E mutation showed continuous metabolic (+8% and + 39%, respectively) and morphologic progression after 2 and 4 weeks of dabrafenib and trametinib. A tumor rebiopsy showed no additional molecular changes. We changed the treatment to osimertinib and dabrafenib combination and observed an impressive metabolic response (-33%) after 2 weeks by FDG-PET/CT. Conclusions: BRAF V600E mutation has recently been described as a novel molecular resistance mechanism in osimertinib-resistant EGFR-mutant NSCLC. We describe one patient where combined BRAF/MEK inhibition with no additional EGFR-inhibition resulted in a preliminary feasible tumor control, but confirmatory CT staging is pending. In a second patient, co-inhibition of EGFR and BRAF pathway with osimertinib and dabrafenib was needed to overcome BRAF-mediated osimertinib resistance resulting in an impressive early tumor response that was not observed to either single-target inhibition of EGFR or BRAF. FDG-PET/CT was able to monitor tumor dynamics. Updated data will be presented.

Acquired resistance to MET inhibition in MET driven NSCLC

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Background: MET mutations ( MET∆ex14), amplifications or translocations can activate oncogenic signaling in lung cancer and are sensitive to MET inhibition. Acquired resistance to therapy with MET tyrosine kinase inhibitors (TKI) occurs inevitably. Methods: Between 2015 and 2018, eighteen patients with MET-driven NSCLC were treated with capmatinib or crizotinib as single agent at our site. Rebiopsy samples from five patients were analyzed by NGS and fluoreszenz-in-situ hybridization (FISH) at time of progression. Results: Of the five patients with rebiopsy samples at time of progression, two had initially a MET amplification (one patient with low-level and one patient with high-level amplification), two patients had a MET∆ex14 and one patient had a KIF5B-MET fusion. Patient 1 (low-level MET amplification) showed a partial response to crizotinib. The rebiopsy revealed an acquired KRAS mutation as a potential mechanism of resistance. Patient 2 (high-level MET amplification) showed stable disease as best response to capmatinib and patient 3 (MET∆ex14) showed a partial response to capmatinib. Both patients developed acquired HER2 amplifications. Patient 4 ( MET∆ex14) showed initially a partial response to crizotinib. The rebiopsy sample revealed an acquired MET kinase domain mutation (p.D1246N). As preclinical findings suggested that D1246N confers resistance to type I MET inhibitors but remains sensitive to type II inhibitors, cabozantinib was started. A CT six weeks after therapy initiation showed progressive disease. Patient 5 ( KIF5B-MET) had a partial response to crizotinib. An acquired MET p.Y1248H mutation was found at time of progression. Therapy was changed to cabozantinib. A new CT scan is pending. Conclusions: Resistance to MET inhibition is heterogeneous with on- and off-target-mechanisms occurring. We found HER2 amplification as a potential new bypass mechanism. The MET mutation D1246N conferred resistance to type I and type II inhibitors. We describe the first case of an acquired mutation of the MET tyrosine kinase domain in a patient with an oncogenic MET fusion. Further investigations are needed to collect comprehensive data to understand resistance mechanisms in MET inhibition and to develop novel therapeutic strategies.

EATON: An open-label, multicenter, phase I dose-escalation trial of nazartinib (EGF816) and trametinib in patients with EGFR-mutant non-small cell lung cancer – preliminary data on safety and tolerability

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Background: Multiple mechanisms of resistance to EGFR TKIs therapy in EGFR-mutant non-small cell lung cancer (NSCLC) have been described, most often including the acquisition of the secondary resistance mutations in exon 20 of EGFR. Preclinical models and clinical findings have also shown that co-occurring activation of the RAS/MEK pathway may result in reduced EGFR dependency, which may be overcome by co-inhibition of MEK. We thus hypothesize that the combined inhibition of EGFR and MEK may restore sensitivity to EGFR inhibition in patients with acquired resistance to EGFR inhibition and may as well prolong the acquisition of resistance in treatment-naïve patients. Methods: EATON is an international, multicenter, phase I, dose escalation investigator-initiated trial investigating the recommended phase 2 dose (RP2D), safety and preliminary efficacy of the combination of the third-generation EGFR inhibitor EGF816 with the MEK inhibitor trametinib (NCT03516214). Eligibility criteria: Advanced NSCLC harboring EGFR del19 or p.L858R, first-line or after failure of any EGFR TKI including osimertinib, independently of p.T790M status. Patients with high-level MET amplification are excluded. Dose level escalation will be based on a modified traditional cumulative 3+3 design, i.e. “up and down” (dose level 1: 100 mg nazartinib (EGF816) QD + 1 mg trametinib QD). A total number of 24 patients is planned to be enrolled in 8 trial sites in Germany and Spain. At a first stage, 18 (6´3) patients will be treated and evaluated. Exploratory endpoints aim at the identification of potential mechanisms of resistance to the trial treatment by massively parallel sequencing (MPS), FISH, phospho-protein analyses and whole exome/genome sequencing of baseline and PD biopsy tumour tissue. Additionally blood samples for MPS of cell free DNA will be collected throughout the trial treatment. Results: At the time of data-cut off for this abstract, one patient received treatment at dose-level 1. Treatment was withdrawn due to a serious, bacterial soft tissue infection of the hand outside the DLT period. Conclusions: Data on safety and tolerability of the combination of nazartinib and trametinib is premature. Updated results will be presented at the conference. Clinical trial information: NCT03516214.

Genomic Profiling Identifies Outcome-Relevant Mechanisms of Innate and Acquired Resistance to Third-Generation Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor Therapy in Lung Cancer

PURPOSE

Third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are effective in acquired resistance (AR) to early-generation EGFR TKIs in EGFR-mutant lung cancer. However, efficacy is marked by interindividual heterogeneity. We present the molecular profiles of pretreatment and post-treatment samples from patients treated with third-generation EGFR TKIs and their impact on treatment outcomes.

METHODS

Using the databases of two lung cancer networks and two lung cancer centers, we molecularly characterized 124 patients with EGFR p.T790M-positive AR to early-generation EGFR TKIs. In 56 patients, correlative analyses of third-generation EGFR TKI treatment outcomes and molecular characteristics were feasible. In addition, matched post-treatment biopsy samples were collected for 29 patients with progression to third-generation EGFR TKIs.

RESULTS

Co-occurring genetic aberrations were found in 74.4% of EGFR p.T790-positive samples (n = 124). Mutations in TP53 were the most frequent aberrations detected (44.5%; n = 53) and had no significant impact on third-generation EGFR TKI treatment. Mesenchymal-epithelial transition factor (MET) amplifications were found in 5% of samples (n = 6) and reduced efficacy of third-generation EGFR TKIs significantly (eg, median progression-free survival, 1.0 months; 95% CI, 0.37 to 1.72 v 8.2 months; 95% CI, 1.69 to 14.77 months; P ≤ .001). Genetic changes in the 29 samples with AR to third-generation EGFR TKIs were found in EGFR (eg, p.T790M loss, acquisition of p.C797S or p.G724S) or in other genes (eg, MET amplification, KRAS mutations).

CONCLUSION

Additional genetic aberrations are frequent in EGFR-mutant lung cancer and may mediate innate and AR to third-generation EGFR TKIs. MET amplification was strongly associated with primary treatment failure and was a common mechanism of AR to third-generation EGFR TKIs. Thus, combining EGFR inhibitors with TKIs targeting common mechanisms of resistance may delay AR.

K-ras Mutation Subtypes in NSCLC and Associated Co-occuring Mutations in Other Oncogenic Pathways

INTRODUCTION

Although KRAS mutations in NSCLC have been considered mutually exclusive driver mutations for a long time, there is now growing evidence that KRAS-mutated NSCLC represents a genetically heterogeneous subgroup. We sought to determine genetic heterogeneity with respect to cancer-related co-mutations and their correlation with different KRAS mutation subtypes.

METHODS

Diagnostic samples from 4507 patients with NSCLC were analyzed by next-generation sequencing by using a panel of 14 genes and, in a subset of patients, fluorescence in situ hybridization. Next-generation sequencing with an extended panel of 14 additional genes was performed in 101 patients. Molecular data were correlated with clinical data. Whole-exome sequencing was performed in two patients.

RESULTS

We identified 1078 patients with KRAS mutations, of whom 53.5% had at least one additional mutation. Different KRAS mutation subtypes showed different patterns of co-occurring mutations. Besides mutations in tumor protein p53 gene (TP53) (39.4%), serine/threonine kinase 11 gene (STK11) (19.8%), kelch like ECH associated protein 1 gene (KEAP1) (12.9%), and ATM serine/threonine kinase gene (ATM) (11.9%), as well as MNNG HOS Transforming gene (MET) amplifications (15.4%) and erb-b2 receptor tyrosine kinase 2 gene (ERBB2) amplifications (13.8%, exclusively in G12C), we found rare co-occurrence of targetable mutations in EGFR (1.2%) and BRAF (1.2%). Whole-exome sequencing of two patients with co-occurring phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha gene (PIK3CA) mutation revealed clonality of mutated KRAS in one patient and subclonality in the second, suggesting different evolutionary backgrounds.

CONCLUSION

KRAS-mutated NSCLC represents a genetically heterogeneous subgroup with a high frequency of co-occurring mutations in cancer-associated pathways, partly associated with distinct KRAS mutation subtypes. This diversity might have implications for understanding the variability of treatment outcome in KRAS-mutated NSCLC and for future trial design.

Rogaratinib treatment of patients with advanced urothelial carcinomas prescreened for tumor FGFR mRNA expression

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Background: Activation of FGFR signaling is involved in a variety of malignancies including advanced urothelial cancer (UC). Rogaratinib is an oral pan-FGFR kinase inhibitor. We report here the results from a phase I expansion cohort in UC patients prescreened for FGFR1-3 mRNA expression levels and activating mutations. (NCT01976741) Methods: Patients with advanced urothelial carcinomas were selected based on high FGFR1-3 mRNA expression in biopsy specimens. Selected patients were treated with rogaratinib 800mg twice daily until tumour progression, untolerable toxicity, or withdrawal. Tumor response was assessed by RECIST, v1.1. Adverse events were reported using CTCAE v4.03 criteria. Results: A total of 219 UC patients were prescreened for FGFR1-3 mRNA expression levels and FGFR3 activating mutations, with 99 samples (45%) found to be FGFR-positive. Of those, 87% of samples were positive for FGFR3 mRNA, 5% for FGFR1 mRNA and 8% were double FGFR mRNA-positive (FGFR1/2, 1/3 or 2/3). Frequency of FGFR3 activating mutations in UC samples was 7%, all of which also had high FGFR3 mRNA. Fifty two patients (median prior line of treatment 2) started treatment and 51 were evaluable for response. Rogaratinib was generally well tolerated and AEs manageable with dose modification. The most common AEs were diarrhea (49%) and hyperphosphatemia (49%). Objective response rate (ORR) was 24% (12/51; all PRs) and disease control rate (DCR) was 73% (37/51). Eleven of 12 pts with a PR were positive for FGFR3 mRNA, 5 of whom also had FGFR3 mutations, and one patient was positive for FGFR1 mRNA. Ten FGFR-positive UC patients had prior immuno-oncology (I/O) treatment, 9 of whom had progressive disease as best response. For these 10 patients the ORR was 30% and the DCR 80%. Conclusions: Selection of pts for treatment with rogaratinib based on FGFR mRNA expression levels was feasible and identified drug-sensitive patients with and without underlying DNA alterations. Rogaratinib had a favorable safety profile and showed promising anti-tumor activity in UC patients. Responses and disease stabilization were observed with rogoratinib in UC pts refractory to prior I/O treatment. Clinical trial information: NCT01976741.

Co-occurrence of targetable aberrations in non-small cell lung cancer patients harboring MAP2K1 mutations

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Background: MAP2K1 mutations are rare in non-small cell lung cancer (NSCLC) and considered to be mutually exclusive with known driver mutations. Activation of the MEK1-cascade might play a pivotal role in resistance to targeted inhibition of BRAF V600E, EML4-ALK and EGFR T790M. So far, however, only MAP2K1 K57N could be identified and linked functionally to resistance in preclinical models. Clinical trials combining specific inhibitors for predefined NSCLC subgroups with MEK inhibitors are ongoing. We sought to characterize frequency and type of MAP2K1-mutated NSCLC regarding curated targetable aberrations. Methods: Tumor tissue collected consecutively from 4590 NSCLC patients within the German Network Genomic Medicine (NGM) between 07/2014 and 07/2015 was analyzed for MAP2K1 mutations using next-generation sequencing (NGS) with a set of 102 amplicons in 14 genes. Clinical and molecular characteristics of these patients were determined and compared with an internal control group of NSCLC patients and an independent control group of The Cancer Genome Atlas (TCGA). Results: We identified 21 (0.5%) patients with MAP2K1 mutations. They were frequently found in adenocarcinomas (n = 20) and were significantly associated with smoking. The most common MAP2K1 mutation was K57N. Most of the patients (n = 16) had additional oncogenic driver aberrations, including mutations in ALK, EGFR or BRAF, ROS1 rearrangements and MET amplification. TP53 mutations were found in 11 patients. In only five patients (23.8%) MAP2K1 occurred exclusively. TCGA analysis revealed additional 10 patients with MAP2K1 mutations, whereof 9 had additional TP53 mutations and one had BRAF mutation. Whereof most patients in our cohort had stage IV NSCLC, all patients in TCGA were systemic treatment naive. Compared with local stages in TCGA, our findings strongly suggest that targetable co-occurring mutations might occur more frequently in advanced stage NSCLC patients. Conclusions: MAP2K1 mutations co-occur frequently with targetable aberrations in smoking stage IV patients. Combination of targeted therapy against known driver aberrations with MEK inhibitors might be a promising therapeutic approach for such patients.

Molecular panel sequencing of pre-treatment samples to reveal mechanisms of innate resistance to 3rd generation EGFR TKI treatment in T790M-positive NSCLC patients

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Background: Resistance to early generation epidermal growth factor receptor ( EGFR) tyrosine kinase inhibitors (TKI) inevitably develops in EGFR-mutant lung cancer. The secondary EGFR p.T790M mutation is the driving factor in 60% of cases and 3rd generation EGFR TKIs have been developed to overcome T790M-mediated resistance. However, besides T790M other genetic aberrations such as amplifications of MET may contribute to resistance to EGFR inhibition in the same patient. We here report on the systematic analysis of co-occurring genetic aberrations that may influence response to 3rd generation EGFR TKIs. Methods: Thirty-six patients were treated with 3rd generation EGFR TKIs in the setting of acquired resistance to EGFR inhibition in cancer centers in Germany and Switzerland. Pre-treatment samples were analyzed for co-occurring genetic aberrations in a subset of resistance-related genes including MET, HER2, RAS-gene family, PIK3CA, CTNNB1 and PTEN using next-generation sequencing and fluorescence in-situ hybridization assays. We investigated the association between clinical, epidemiological and molecular data and response to treatment (RECIST 1.1). Results: Co-occurring genetic aberrations were found in 68% of the pre-treatment samples where both, analyses by sequencing and FISH were feasible (N = 25). Efficacy of 3rd generation EGFR TKIs significantly dropped in the presence of high-level MET amplification as compared to wild-type MET (ORR, 0.0%; 95% CI, 0.0-60.4 vs. 70.0%; 95% CI, 45.7-87.2; p = 0.02; median PFS, 1.0 month; 95% CI, 0.37-1.72 months vs. 8.2 months; 95% CI, 1.69-14.77 months; p ≤ 0.001). No statistically significant association was found between treatment efficacy and the molecular status of the genes analyzed or the number of prior EGFR TKIs. Conclusions: Prevalence of additional genetic aberrations is frequent in the setting of acquired resistance to early generation EGFR TKIs and may not necessarily mediate resistance to 3rd generation EGFR TKIs. However, in our analysis high-level amplification of MET was associated with primary treatment failure and might be the main factor underlying resistance in this setting.

Expanded molecular routine testing for targetable mutations in non-small cell lung cancer to reveal frequent co-occuring mutations

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Background: Using next-gen sequencing of predefined gene panels in routine clinical diagnostics of lung cancer allows, in contrast to single-gene assays, assessment of co-occuring mutations, which might underly heterogeneity of response to targeted drugs and survival. The Network Genomic Medicine (NGM) performs high sensitive next generation sequencing (NGS) based routine molecular diagnostics on a central platform for about 5000 inoperable lung cancer patients (pts) annually in Germany. Methods: NGS panel used in NGM consists of 17 genes to cover potentially targetable aberrations. Mutation analyses were run on an Illumina (MySeq) platform, while FISH analyses were performed separately. In 2016, we have started the evaluation of all NGM pts with available clinical data who had received NGS-based molecular diagnostics. In particular, we have focused on non-squamous (non-sq) and squamous (sq) NSCLC pts with co-occurring mutations: their frequency, significance and impact on overall survival. Results: From 2014 molecular genotyping was performed for 7,893 NGM pts (n = 7,246 NSCLC (5,667 non-sq and 1,487 sq pts) and n = 489 SCLC) with eligible clinical data. Genetic alterations in transformation-associated pathways were found in 79 % of all NSCLC pts. Furthermore, co-occurring mutations were detected in 39 % of these pts: 40 % in non-sq and 37 % in sq NSCLC. 11 % of pts had more than 2 co-occurring mutations. 1 % of all pts had 5 co-occurring mutations. The most frequent paired mutations were KRAS, EGFR and MET each with TP53 in non-sq and FRGF1 and TP53 in sq NSCLC. The incidences and significance of 3, 4 and 5 co-mutations as well as the impact of these co-occurring mutations on overall survival will be presented. Conclusions: Frequent occurrence of co-occuring mutations in transformation – associated pathways underlines the genetic heterogeneity also of lung cancer with classical driver mutation and the impact of co-occurring mutations on survival. This work confirms the use of molecular multiplex testing in routine molecular diagnostics of NSCLC. Assessment of co-occuring mutations will help to further specify genetically defined subgroups of lung cancer with therapeutic relevance.

Fibroblast kinase 1-3 inhibitor BGJ398 in patients with FGFR1 amplified squamous non-small cell lung cancer treated in a phase I study: Evaluation of tumor tissue and response at a single center

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Background: Fibroblast growth factor receptor 1 ( FGFR1) amplification in squamous cell non-small cell lung cancer (sqNSCLC) has been described as potential oncogenic and targetable driver in cell lines and murine models. However, a phase I study evaluating FGFR 1-3 inhibitor BGJ398 showed moderate response rate of 11% in FGFR1amplified sgNSCLC treated with dose ≥ 100mg. To identify underlying mechanisms of resistance, we analyzed tumor tissues of selected patients. Methods: Within the phase I BGJ398 study, patients (pts) with FGFR1amplified sqNSCLC were treated orally with escalating dose (5 to 150mg) of BGJ398 once daily (QD) or 50mg twice a day. In the expansion phase, pts received BGJ398 either continuously QD or on a 3-weeks on/1-week off schedule. CT scans for response were performed every 8 weeks. Available tumor tissue of pts treated with BGJ398 at our center was analyzed using hybrid capture–based massively parallel sequencing (CAGE). Results: Twenty-one pts with FGFR1 amplified sqNSCLC were treated with ≥ 100mg BGJ398 at our site. As best response, 3 pts showed partial response (PR), 7 pts stable disease (SD) and 7 pts progressive disease (PD). Two pts withdrew their consents and 2 pts died ahead of first CT scan: one due to infection and one due to sudden death. We performed CAGE covering 256 genes on 9 patients: on 3 pts with PR, 2 pts with SD, 2 pts with PD and 2 pts who died before first CT scan. All analyzed patients harbored mutations in TP53. Additionally, we detected two CDKN2A (one patient with PR and one patient who died before first CT) and three MLL2 stop codon and frame shift mutations (two patients with SD and one patient with PD). Of interest, we identified three patients with two canonical (one patient with SD and one patient who died before first CT) and one non-canonical mutations in PIK3CA(one patient with SD). Conclusions: In our analysis, MLL2 and PIK3CA mutations seem to have a negative impact on response in FGFR1 amplified pts treated with BGJ398. Further analysis with higher patient number is needed to identify the role of MLL2 and PIK3CA mutations in FGFR1 amplified sqNSCLC. Clinical trial information: NCT01004224.