A Phase 1 Study to Evaluate Absolute Bioavailability and Absorption, Distribution, Metabolism, and Excretion of Savolitinib in Healthy Male Volunteers

Savolitinib is an oral MET (hepatocyte growth factor receptor) tyrosine kinase inhibitor, with demonstrated preliminary efficacy in several cancer types. Previous pharmacokinetics assessments showed that savolitinib is rapidly absorbed but there are limited data on the absolute bioavailability and absorption, distribution, metabolism, and excretion (ADME) of savolitinib. This open-label, two-part, phase 1 clinical study (NCT04675021) used a radiolabeled micro-tracer approach to evaluate absolute bioavailability and a traditional approach to determine the ADME of savolitinib in healthy male adult volunteers (N = 8). Pharmacokinetics, safety, and metabolic profiling and structural identification from plasma, urine, and fecal samples were also assessed. Volunteers received a single oral savolitinib 600 mg dose followed by intravenous 100 μg of [¹⁴ C]savolitinib in Part 1 and a single oral 300 mg [¹⁴ C]savolitinib dose (≤4.1 MBq [megabecquerel] [¹⁴ C]) in Part 2. Following Part 1, absolute oral bioavailability was 69%, the median time of maximum observed concentration was 3.5 hours, and the mean terminal half-life was 6.1 hours. Following Part 2, 94% of the radioactivity administered was recovered, with 56% and 38% in urine and feces, respectively. Exposure to savolitinib and metabolites M8, M44, M2, and M3 accounted for 22%, 36%, 13%, 7%, and 2%, respectively, of plasma total radioactivity. Approximately 3% of the dose was excreted as unchanged savolitinib in urine. Most savolitinib elimination occurred via metabolism by several different pathways. No new safety signals were observed. Our data show that the oral bioavailability of savolitinib is high and the majority of savolitinib elimination occurs via metabolism and is excreted in the urine.

Osimertinib + Savolitinib to Overcome Acquired MET-Mediated Resistance in Epidermal Growth Factor Receptor-Mutated, MET-Amplified Non-Small Cell Lung Cancer: TATTON

MET-inhibitor and EGFR tyrosine kinase inhibitor (EGFR-TKI) combination therapy could overcome acquired MET-mediated osimertinib resistance. We present the final phase Ib TATTON (NCT02143466) analysis (Part B, n = 138/Part D, n = 42) assessing oral savolitinib 600 mg/300 mg once daily (q.d.) + osimertinib 80 mg q.d. in patients with MET-amplified, EGFR-mutated (EGFRm) advanced non-small cell lung cancer (NSCLC) and progression on prior EGFR-TKI. An acceptable safety profile was observed. In Parts B and D, respectively, objective response rates were 33% to 67% and 62%, and median progression-free survival (PFS) was 5.5 to 11.1 months and 9.0 months. Increased antitumor activity may occur with MET copy number ≥10. EGFRm circulating tumor DNA clearance on treatment predicted longer PFS in patients with detectable baseline ctDNA, while acquired resistance mechanisms to osimertinib + savolitinib were mediated by MET, EGFR, or KRAS alterations.

SIGNIFICANCE

The savolitinib + osimertinib combination represents a promising therapy in patients with MET-amplified/overexpressed, EGFRm advanced NSCLC with disease progression on a prior EGFR-TKI. Acquired resistance mechanisms to this combination include those via MET, EGFR, and KRAS. On-treatment ctDNA dynamics can predict clinical outcomes and may provide an opportunity to inform earlier decision-making. This article is highlighted in the In This Issue feature, p. 1.

Osimertinib plus Selumetinib in EGFR-Mutated Non-Small Cell Lung Cancer After Progression on EGFR-TKIs: A Phase Ib, Open-Label, Multicenter Trial (TATTON Part B)

BACKGROUND

MEK/ERK inhibition can overcome acquired resistance to osimertinib in preclinical models. Osimertinib [EGFR-tyrosine kinase inhibitor (TKI)] plus selumetinib (MEK1/2 inhibitor) was assessed in the global TATTON study.

METHODS

This multicenter, open-label, phase Ib study expansion cohort enrolled patients (aged ≥18 years) with MET-negative, EGFRm advanced NSCLC who had progressed on EGFR-TKIs. Patients were assigned to one of two cohorts by prior first- or second-generation or T790M-directed EGFR-TKI and received osimertinib 80 mg every day and intermittent selumetinib 75 mg twice a day orally. Safety and tolerability (primary objective) and antitumor activity determined by objective response rate (ORR), and progression-free survival (PFS) using RECIST v1.1 were assessed. Data cutoff: March 4, 2020.

RESULTS

Forty-seven patients received treatment (prior first- or second-generation EGFR-TKI, n = 12; prior T790M-directed EGFR-TKI, n = 35). Forty-four (94%) patients were Asian; 30 (64%) had baseline exon 19 deletion. Most common AEs were diarrhea (89%), decreased appetite (40%), and stomatitis (32%); 11/47 patients (23%) had an AE Grade ≥3 possibly causally selumetinib-related. ORR was 66.7% [95% confidence interval (CI), 34.9-90.1] in the prior first- or second-generation EGFR-TKI group, 22.9% (95% CI, 10.4-40.1) in the prior T790M-directed EGFR-TKI group, and 34.0% (95% CI, 20.9-49.3) overall; median PFS was 15.0 (95% CI, 2.7-33.0), 2.8 (95% CI, 1.6-5.5), and 4.2 months (95% CI, 2.7-7.2), respectively.

CONCLUSIONS

In this small study, AEs and tolerability of osimertinib plus selumetinib were as expected, on the basis of previous studies. The combination demonstrated antitumor activity supportive of further investigation in patients with MET-negative, EGFRm advanced NSCLC who had progressed on a previous EGFR-TKI.

Brief Report: Osimertinib Plus Durvalumab in Patients with EGFR-Mutated, Advanced Non-Small Cell Lung Cancer: A Phase 1b, Open-Label, Multicenter Trial

INTRODUCTION

EGFR-TKIs are recommended for EGFR-mutated NSCLC treatment. EGFR activation upregulates programmed cell death-ligand 1 (PD-L1) expression and other immunosuppressive factors in NSCLC, causing immune microenvironment remodeling. Osimertinib (an EGFR-TKI) plus durvalumab (PD-L1 blockade) was assessed in the TATTON study (NCT02143466).

METHODS

This open-label, phase 1b study enrolled patients with advanced EGFR-mutated NSCLC. In Part A, patients who had progressed on a prior EGFR-TKI received osimertinib (80 mg once daily) plus durvalumab 3 or 10 mg/kg every 2 weeks (Q2W). In Part B, patients received first-line osimertinib plus durvalumab 10 mg/kg Q2W. However, Part B enrollment was terminated early due to an increased incidence of interstitial lung disease (ILD)-related adverse events (AEs). Safety (primary objective) and preliminary anti-tumor activity determined by objective response rate (ORR), best overall response (BOR), duration of response (DOR) and progression-free survival (PFS) were assessed.

RESULTS

Before enrollment termination, 23 and 11 patients received treatment across Parts A and B, respectively. The most common AEs across Parts A and B were: diarrhea (50%), nausea (41%) and decreased appetite (35%). Twelve patients (35%) reported ILD-related AEs (lung disorder/ILD/pneumonitis). In Part A, ORR was 43% (95% CI: 23ꟷ66); median DOR was 20.4 months. In Part B, ORR was 82% (48ꟷ98), median DOR was 7.1 months and median PFS was 9.0 months (3.5ꟷ12.3).

CONCLUSIONS

This study highlighted a potential risk of ILD-related AEs when combining osimertinib with durvalumab. Further research looking to combine EGFR-TKIs with immune checkpoint inhibitors should be approached with caution.

Clinical evaluation of the potential drug-drug interactions of savolitinib: Interaction with rifampicin, itraconazole, famotidine or midazolam

Aims

We investigated savolitinib pharmacokinetics (PK) when administered alone or in combination with rifampicin, itraconazole or famotidine, and investigated midazolam PK when administered with or without savolitinib in healthy males.

Methods

Savolitinib PK was evaluated before/after: rifampicin (600 mg once daily [QD] for 5 days); itraconazole (200 mg QD for 5 days); a single dose of famotidine (40 mg QD) 2 hours before savolitinib. Midazolam PK was evaluated before/after midazolam (1 mg QD) with or without savolitinib (600 mg QD). Each study enrolled 20, 16, 16 and 14 volunteers, respectively. Plasma samples were collected to determine the effect on PK.

Results

The geometric mean ratios (GMR, %) (90% confidence intervals [CIs]) for savolitinib alone and in combination for C_max, AUC respectively, were 45.4 (41.4–49.9), 38.5 (34.2–43.3) in the rifampicin study (n = 18); 105.2 (87.7–126.3), 108.4 (96.3–122.1) in the itraconazole study (n = 16); and 78.8 (67.7–91.7), 87.4 (81.2–94.2) in the famotidine study (n = 16). The GMRs (90% CIs) for midazolam alone and in combination with savolitinib for C_max, AUC respectively, were 84.1 (70.0–101.0), 96.7 (92.4–101.1) (n = 14). Savolitinib alone or in combination was well tolerated.

Conclusions

Co‐dosing of rifampicin significantly reduced exposure to savolitinib vs savolitinib alone; co‐dosing of itraconazole or midazolam with savolitinib had no clinically significant effect on savolitinib or midazolam PK, respectively. Co‐dosing of famotidine with savolitinib reduced exposure to savolitinib, although this was not considered clinically meaningful. No new savolitinib‐related safety findings were observed.

Abstract CT127: Tumor response and MET-detection methods exploratory biomarker analysis of Part B of the Ph 1b TATTON study

Background/Purpose Following disease progression on osimertinib, a third generation (3G), irreversible, oral epidermal growth factor receptor tyrosine kinase inhibitor (EGFR TKI), ≤22% of patients (pts) with EGFR mutation positive (EGFRm) non-small cell lung cancer (NSCLC) develop MET-amplification as a resistance mechanism to treatment. In the Ph1b TATTON (NCT02143466) Part B expansion cohort, pts with MET-amplified EGFRm advanced NSCLC and progression on a prior EGFR-TKI received osimertinib + savolitinib, an oral, potent and highly selective MET TKI. Previous analyses have compared MET patient selection assays and found that different methods identify different but partially overlapping proportions of pts with MET amplification or overexpression. Here, we report the response rates observed in the subgroups defined by the different central MET assays in TATTON Part B. Methods MET testing (central, or local with central confirmation) was performed on tumor tissue collected after the most recent therapy. MET assays included FISH (MET gene copy number ≥5 or MET-CEP7 ratio ≥2) and IHC (MET +3 expression in ≥50% of tumor cells). TATTON Part B was split into 3 pt cohorts: pts previously treated with a 3G EGFR TKI and not previously treated with a 3G EGFR TKI (T790M positive/negative). This analysis uses the final study data (cutoff 4 March 2020) to compare the objective response rate (ORR) of subgroups identified by each assay. Results For pts who had received prior treatment with a 3G EGFR TKI, ORR by MET assay was as follows: FISH-positive overall (n=53) 30%; FISH polysomy (n=18) 28%; FISH amplification (n=35) 31%; IHC (n=13) 46%. For FISH-positive tumors, ORR trended higher for tumors with ≥10 MET gene copies (n=29, 35%) vs tumors with 5-9 copies (n=24, 25%). For pts with no prior treatment with a 3G EGFR TKI (T790M negative), ORR was as follows: FISH-positive overall (n=34) 65%; FISH polysomy (n=14) 57%; FISH amplification (n=20) 70%; IHC (n=4) 75%. For FISH-positive tumors, ORR trended higher for tumors with ≥10 MET gene copies (n=14, 79%) vs tumors with 5-9 copies (n=20, 55%). In tumors with both central FISH and IHC data available (n=34), IHC positivity (n=20) and FISH positivity (n=27) were correlated, specifically IHC and FISH amplification: 13/16 cases of FISH amplification were also IHC positive. In FISH-positive tumors IHC expression tended to increase with increasing gene copy number (≥10), but outcomes were largely comparable. Conclusions Overall, the MET assays were comparable with regards to ORR, thus supporting continued use of both FISH and IHC for detection of MET in pts following disease progression on any 3G EGFR TKI, though IHC data were limited. Further study is warranted in this area: the SAVANNAH (NCT03778229; FISH and IHC) and ORCHARD (NCT03944772; NGS) studies will provide opportunity for further analyses.

Citation Format: Ryan Hartmaier, Ji-Youn Han, Byoung Chul Cho, Aleksandra Markovets, Nisha Kurian, Mireille Cantarini, Pasi A. Janne. Tumor response and MET-detection methods exploratory biomarker analysis of Part B of the Ph 1b TATTON study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT127.

Abstract CT024: Acquired resistance in patients with EGFRm NSCLC following treatment with osimertinib plus savolitinib in the Ph1b TATTON study Parts B and D

Background/Purpose: MET-amplification is a resistance mechanism seen in ≤22% of patients (pts) with epidermal growth factor receptor mutation positive (EGFRm) non-small cell lung cancer (NSCLC) following progression on osimertinib, a third generation (3G), irreversible, oral EGFR tyrosine kinase inhibitor (TKI). In the Ph1b TATTON (NCT02143466) expansion cohorts (Parts B and D), pts with MET-amplified EGFRm advanced NSCLC and progression on a prior EGFR TKI, received osimertinib 80 mg + savolitinib 600 or 300 mg once daily; savolitinib is an oral, potent and highly selective MET TKI. Part B was split into three cohorts by prior therapy and tumor T790M status. Part D pts had received no prior 3G EGFR TKI and were T790M negative. For pts who eventually develop resistance to the combination, it is unclear which driver mutation(s) mediates this resistance. Methods: In this analysis, paired plasma samples collected at baseline and following disease progression and/or treatment discontinuation up to data cut-off date 4 March 2020, were assessed. Next generation sequencing (Guardant Health, Guardant360 73 gene panel or Omni 500 gene panel) was used to analyze the plasma ctDNA samples. All 73 genes on the Guardant360 panel were included in the Omni 500 gene panel. Analyses from each pt were reported only for genes included across the panels used. Genomic alterations were identified using Guardant Health's pipeline, which included mutations and amplifications of EGFR and MET. Disease progression was assessed by the investigator, according to the RECIST version 1.1. Assessments were completed for pts with progression-free survival (PFS) of over 2 months. Results: Of 180 pts who received study treatment, 70 provided baseline and progression/discontinuation ctDNA plasma samples. Of these, 45 pts were used for the analysis: 18/70 were not evaluable for ctDNA detection and 7/70 had a PFS of 2 months or shorter. Of the evaluable samples, the following acquired mutations were recorded (exclusivity between genes in most pts): MET D1228X, Y1230X, L1212X (20%, 9/45), EGFR C797X (16%, 7/45), KRAS G12X, G13X (11%, 5/45) and PIK3CA E545K (4%, 2/45). Most pts who developed MET-based resistance (7/9) developed more than one MET mutation, suggestive of polyclonal resistance. Across both Parts B and D, the resistance profiles appeared similar by prior EGFR TKI status and by savolitinib dose. Conclusions: In this analysis, approximately half of all evaluable pts had an identifiable acquired resistance mechanism; resistance appeared to be predominantly mediated by either MET, EGFR or KRAS. Co-occurring mutations across multiple genes were rarely detected. However, multiple acquired mutations were often detected in a specific gene, particularly MET, suggesting individual tumors showed inherent resistance dependencies.

Citation Format: Aleksandra Markovets, Ji-Youn Han, Byoung Chul Cho, Mireille Cantarini, Pasi A. Janne, Ryan Hartmaier. Acquired resistance in patients with EGFRm NSCLC following treatment with osimertinib plus savolitinib in the Ph1b TATTON study Parts B and D [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT024.

Abstract CT303: The effect of savolitinib plus osimertinib on ctDNA clearance in patients with EGFR mutation positive (EGFRm) MET-amplified NSCLC in the TATTON study

MET-amplification is a resistance mechanism seen in >25% of pts with EGFRm non-small cell lung cancer (NSCLC) and progression on osimertinib (1st/later line), a 3rd gen, irreversible, oral EGFR-TKI. Savolitinib (AZD6094, HMPL-504, volitinib) is an oral, potent and highly selective MET-TKI. In Phase 1b TATTON (NCT02143466) expansion cohorts (Parts B and D), pts with MET-amplified EGFRm advanced NSCLC and progression on a prior EGFR-TKI received osimertinib 80 mg + savolitinib 600/300 mg. Part B was split into cohorts (B1, B2 and B3) by prior therapy and T790M status. Pts in Part D (no prior 3rd gen EGFR-TKI, T790M negative; savolitinib 300 mg) had similar response rates and progression-free survival (PFS) to pts in cohort B2 (analogous cohort; savolitinib 600 mg). In osimertinib-treated pts with EGFRm NSCLC (AURA3, FLAURA), circulating tumor (ct)DNA clearance has been shown to correlate with PFS. We report EGFRm (Ex19del/L858R) ctDNA clearance at two doses of savolitinib + osimertinib 80 mg in TATTON Parts B and D. For this next generation sequencing-based analysis (Resolution Bioscience), ctDNA samples were collected pre-dose, cycle (C) 1 day (D) 1 and at least every 3-8 weeks until discontinuation. Part B pts evaluable for efficacy and with a baseline plus ≥1 longitudinal ctDNA sample at/before C6D1 were included. Data from ctDNA evaluable Part B pts (n=49) identified ctDNA clearance correlates with longer PFS and C3D1/C4D1 as optimal time points for PFS prediction, thus the first 20 pts from Part D with available plasma samples at C1D1 and C4D1 were included. The proportion of pts with detectable EGFRm at baseline was similar across groups (Table). ctDNA clearance was comparable at C3D1/C4D1 for cohort B2 and Part D. ctDNA clearance was similar between the two doses of savolitinib, suggesting efficacy is maintained at the lower dose (300 mg). These data also indicate that ctDNA clearance may be predictive of PFS in EGFRm MET-amplified NSCLC.

TATTON Part B and Part D ctDNA analysisPart B: osimertinib 80 mg QD + savolitinib 600 mg QD (n=107)*Part D: osimertinib 80 mg QD + savolitinib 300 mg QD (n=42)#All Part BCohort B2 No prior third-generation EGFR-TKI (T790M negative)All Part D No prior third-generation EGFR-TKI (T790M negative)Number of patients492020Detectable EGFRm at baseline, n (%)38 (78)15 (75)16 (80)ctDNA clearanceNumber of pts evaluable at C3D1/C4D1451820ctDNA clearance at C3D1/C4D1, n (%)22 (45)10 (50)13 (65)‡*Interim data cut-off: 28 Feb 2018 #Interim data cut-off: 29 Mar 2019 ‡ctDNA clearance for patients at Part D was only assessed at C4D1

Citation Format: Ryan Hartmaier, Ji-Youn Han, Myung-Ju Ahn, Byoung Chul Cho, Mireille Cantarini, Paul Frewer, Melanie M. Frigault, Geoffrey Oxnard. The effect of savolitinib plus osimertinib on ctDNA clearance in patients with EGFR mutation positive (EGFRm) MET-amplified NSCLC in the TATTON study [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT303.

Impact of Disease and Treatment Response in Drug-Drug Interaction Studies: Osimertinib and Simvastatin in Advanced Non-Small Cell Lung Cancer

A phase I, open‐label study (NCT02197234) assessed the effects of osimertinib on simvastatin exposure in patients with advanced epidermal growth factor receptor (EGFR)‐mutated non‐small cell lung cancer and disease progression post‐EGFR tyrosine kinase inhibitor treatment. Here, we report on a retrospective analysis of two patients (patients 1 and 2) who had liver metastases and high simvastatin exposure prior to osimertinib treatment, which changed following treatment. Patients received single oral doses of simvastatin 40 mg on day (D) 1 and D31, and osimertinib 80 mg once daily on D3–32. At baseline, both patients had abnormal liver function tests (LFTs; Child‐Pugh scores of 6 and 8, respectively), significant liver metastasis, and, after a single simvastatin dose, had higher (~ 10‐fold) exposure compared with all other patients. Following 31 days of continuous osimertinib treatment, simvastatin exposures (area under the plasma concentration‐time curve from zero to infinity (AUC) and maximum plasma concentration (C_max)) and LFTs, such as alanine transaminase, aspartate aminotransferase, and bilirubin normalized to population mean values. Additionally, ~ 50% and ~ 80% reductions in liver metastases were observed on computed tomography scans in patients 1 and 2, respectively. High simvastatin exposure on D1 likely resulted from impairment of hepatic first pass metabolism due to liver metastases. Reduction in hepatic disease burden due to osimertinib treatment likely resulted in liver function returning to normal levels.

Abstract CT034: Osimertinib plus selumetinib for patients (pts) with EGFR-mutant (EGFRm) NSCLC following disease progression on an EGFR-TKI: Results from the Phase Ib TATTON study

The EGFR T790M mutation is the most common cause of resistance in pts receiving a first or second-generation EGFR-TKI for EGFRm NSCLC. Other resistance mechanisms include upregulation of the RAS/RAF/MEK/ERK signaling pathway. The Phase Ib TATTON study (NCT02143466) assessed osimertinib in combination with novel therapeutics including the oral, potent and selective MEK1/2 inhibitor, selumetinib (AZD6244, ARRY-142886). Here we present data from the dose-finding (Part A) and dose expansion (Part B) portions of this study. Adults with advanced EGFRm NSCLC and disease progression on prior EGFR-TKI, including third-generation agents, were eligible regardless of T790M or KRAS status. In Part A, pts received osimertinib 80 mg QD plus intermittent or continuous selumetinib. Asian pts received continuous selumetinib 25/50 mg BID, while other pts received continuous selumetinib 50/75 mg BID, or intermittent selumetinib 75 mg BID 4 days on/3 days off (4/3), or on days 1 and 4 of each week of treatment. In Part B, pts received osimertinib plus intermittent selumetinib 75 mg BID 4/3. Primary objectives were safety, tolerability and preliminary efficacy (objective response rate [ORR]). Secondary objectives included duration of response (DoR) and pharmacokinetics (PK). At data cut-off (Feb 2018), 36 and 47 pts received treatment in Parts A and B, respectively. In Part A, most pts were white (18, 50%) or Asian (17, 47%), and 26 (72%) had a baseline exon 19 deletion. In Part B, 44 (94%) pts were Asian, and 30 (64%) had a baseline exon 19 deletion. The most common treatment-related adverse events (TRAEs) in Part A were diarrhea (27, 75%), nausea (14, 39%) and fatigue (12, 33%). Six pts had dose-limiting toxicities (DLTs) with continuous selumetinib (all Grade 3): ALT and AST increase (50 mg); diarrhea, asthenia and dizziness (50 mg); diarrhea (n=2, 75 mg); diarrhea and nausea (75 mg); and pneumonitis (75 mg). No DLTs were reported with intermittent dosing, so the selumetinib 4/3 schedule was selected for Part B. The most common TRAEs in Part B were diarrhea (38, 81%), stomatitis (15, 32%), and paronychia (14, 30%). In Part A, 15 (42%) pts had confirmed partial response (PR); 14 (39%) had stable disease at 6 weeks (SD); 3 (8%) had progressive disease (PD); 2 (6%) died; and 2 (6%) were not evaluable (NE). Median DoR was 16.6 months; 77% remained in response at 12 months. In Part B, 16 (34%) pts had confirmed PR; 16 (34%) had SD; 11 (23%) had PD; 2 (4%) died; and 2 (4%) were NE. Median DoR was 9.1 months; 31% remained in response at 12 months. Osimertinib and selumetinib PK parameters were similar to those previously observed with monotherapy. Osimertinib plus intermittent selumetinib had an acceptable safety profile and demonstrated preliminary anti-tumor activity in pts with disease progression on a prior EGFR-TKI. Responses were durable and this combination warrants further investigation.

Citation Format: Suresh S. Ramalingam, Hideo Saka, Myung-Ju Ahn, Helena Yu, Helena Yu, Leora Horn, Toyoaki Hida, Mireille Cantarini, Remy Verheijen, Jonathan Wessen, Geoffrey Oxnard, Yuichiro Ohe. Osimertinib plus selumetinib for patients (pts) with EGFR-mutant (EGFRm) NSCLC following disease progression on an EGFR-TKI: Results from the Phase Ib TATTON study [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 CT034.

SAVANNAH: A Phase II trial of osimertinib plus savolitinib for patients (pts) with EGFR-mutant, MET-driven (MET+), locally advanced or metastatic non-small cell lung cancer (NSCLC), following disease progression on osimertinib

TPS9119

Background: The toxicity profile of the third-generation EGFR-tyrosine kinase inhibitor (TKI) osimertinib makes it an attractive backbone for combination with other targeted agents, possibly overcoming acquired resistance mechanisms. Combination with a MET-inhibitor is an intuitive approach as MET-amplification was identified as the most common mechanism of resistance to osimertinib in preliminary ctDNA data from the Phase III FLAURA (15% of pts) and AURA3 (19% of pts) studies. Savolitinib (AZD6094, HMPL-504, volitinib) is an oral, potent and highly selective MET-TKI that had an acceptable safety profile when combined with osimertinib in the Phase Ib TATTON study, providing the basis for this Phase II SAVANNAH study (NCT03778229). Other mechanisms of acquired resistance to osimertinib, including secondary EGFR mutations (e.g. C797S), RAS/RAF activation, and oncogenic gene fusions, provide additional opportunities for developing osimertinib-based combinations. Methods: Eligible pts will have histologically/cytologically confirmed EGFR-mutant NSCLC, and MET+ disease by central FISH, central IHC, or local NGS (retrospectively confirmed by central FISH/IHC). Pts must have documented radiological progression following 1–3 lines of prior therapy (must include osimertinib). Pts will receive osimertinib 80 mg plus weight-based dosing with savolitinib 300 or 600 mg PO QD, in 28-day cycles. The primary objective is efficacy (RECIST 1.1) by overall response rate (ORR) in pts who are MET+ by central FISH. Secondary endpoints include: ORR ( MET+ by central IHC and all pts); progression-free survival, overall survival, duration of response, percent change in tumor size, HRQoL, and EGFR mutation ctDNA clearance ( MET+ by central FISH, central IHC, and all pts); safety, and pharmacokinetics (all pts). Based on the TATTON study, we anticipate enrolling ~172 MET+ pts to include ≥117 pts with MET+ disease by central FISH. Enrolment began in Q1 2019. Ongoing development of complementary trials targeting other osimertinib resistance mechanisms will also be discussed. Clinical trial information: NCT03778229.

CNS response to osimertinib in patients with T790M-positive advanced NSCLC: pooled data from two phase II trials

Background

Central nervous system (CNS) metastases are common in patients with non-small-cell lung cancer (NSCLC). Osimertinib has shown systemic efficacy in patients with CNS metastases, and early clinical evidence shows efficacy in the CNS. To evaluate osimertinib activity further, we present a pre-specified subgroup analysis of CNS response using pooled data from two phase II studies: AURA extension (NCT01802632) and AURA2 (NCT02094261).

Patients and methods

Patients with T790M-positive advanced NSCLC, who had progressed following prior epidermal growth factor receptor-tyrosine kinase inhibitor treatment, received osimertinib 80 mg od (n = 411). Patients with stable, asymptomatic CNS metastases were eligible for enrolment; prior CNS treatment was allowed. Patients with ≥1 measurable CNS lesion (per RECIST 1.1) on baseline brain scan by blinded independent central neuroradiology review (BICR) were included in the evaluable for CNS response set (cEFR). The primary outcome for this CNS analysis was CNS objective response rate (ORR) by BICR; secondary outcomes included CNS duration of response, disease control rate (DCR) and progression-free survival (PFS).

Results

Of 128 patients with CNS metastases on baseline brain scans, 50 were included in the cEFR. Confirmed CNS ORR and DCR were 54% [27/50; 95% confidence interval (CI) 39-68] and 92% (46/50; 95% CI 81-98), respectively. CNS response was observed regardless of prior radiotherapy to the brain. Median CNS duration of response (22% maturity) was not reached (range, 1-15 months); at 9 months, 75% (95% CI 53-88) of patients were estimated to remain in response. Median follow-up for CNS PFS was 11 months; median CNS PFS was not reached (95% CI, 7, not calculable). The safety profile observed in the cEFR was consistent with the overall patient population.

Conclusions

Osimertinib demonstrated clinically meaningful efficacy against CNS metastases, with a high DCR, encouraging ORR, and safety profile consistent with that reported previously.

ClinicalTrials.gov number

NCT01802632; NCT02094261.

Osimertinib in patients with T790M mutation-positive, advanced non-small cell lung cancer: Long-term follow-up from a pooled analysis of 2 phase 2 studies

BACKGROUND

Osimertinib is a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) that is selective for both EGFR-TKI-sensitizing and T790M (threonine-to-methionine substitution at codon 790)-resistance mutations. The authors present long-term follow-up data from a preplanned, pooled analysis of phase 2 studies, the AZD9291 First Time in Patients Ascending Dose Study (AURA) extension trial (clincialtrials.gov identifier NCT01802632) and the AURA2 trial (NCT02094261).

METHODS

Patients with centrally confirmed, T790M mutation-positive, advanced non-small cell lung cancer received osimertinib 80 mg once daily until disease progression or study discontinuation. Response was assessed by a blinded, independent, central review using Response Evaluation Criteria in Solid Tumors, version 1.1. The primary endpoint was the objective response rate.

RESULTS

In total, 411 patients received osimertinib (second line, 129 patients; third line or later, 282 patients). At the data cutoff date of November 1, 2016, the median treatment exposure was 16.4 months (range, 0-29.7 months), the objective response rate was 66% (95% confidence interval [CI], 61%-70%), the median response duration was 12.3 months (95% CI, 11.1-13.8 months), and the median progression-free survival was 9.9 months (95% CI, 9.5-12.3 months). At the data cutoff date of May 1, 2018, 271 patients (66%) had died, and 140 patients (34%) had discontinued before death. The median overall survival was 26.8 months (95% CI, 24.0-29.1 months); and the 12-month, 24-month, and 36-month survival rates were 80%, 55%, and 37%, respectively. Grade ≥3 possibly causally related (investigator assessed) adverse events were reported in 65 patients (16%), and the most common were rash (grouped terms; 42%; grade ≥3, 1%) and diarrhea (39%; <1%).

CONCLUSIONS

This pooled analysis represents the most mature clinical trial data for osimertinib in patients with pretreated, T790M-positive, advanced non-small cell lung cancer, further establishing osimertinib as a standard of care for this patient population.

Osimertinib in patients with epidermal growth factor receptor T790M advanced non-small cell lung cancer selected using cytology samples

Osimertinib is a potent, irreversible epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) selective for EGFR‑TKI sensitizing (EGFRm) and T790M resistance mutations. The primary objective of the cytology cohort in the AURA study was to investigate safety and efficacy of osimertinib in pretreated Japanese patients with EGFR T790M mutation‐positive non‐small cell lung cancer (NSCLC), with screening EGFR T790M mutation status determined from cytology samples. The cytology cohort was included in the Phase I dose expansion component of the AURA study. Patients were enrolled based on a positive result of T790M by using cytology samples, and received osimertinib 80 mg in tablet form once daily until disease progression or until clinical benefit was no longer observed at the discretion of the investigator. Primary endpoint for efficacy was objective response rate (ORR) by investigator assessment. Twenty‐eight Japanese patients were enrolled into the cytology cohort. At data cut‐off (February 1, 2016), 12 (43%) were on treatment. Investigator‐assessed ORR was 75% (95% confidence interval [CI] 55, 89) and median duration of response was 9.7 months (95% CI 3.8, not calculable [NC]). Median progression‐free survival was 8.3 months (95% CI 4.2, NC) and disease control rate was 96% (95% CI 82, 100). The most common all‐causality adverse events were paronychia (46%), dry skin (46%), diarrhea (36%) and rash (36%). Osimertinib provided clinical benefit with a manageable safety profile in patients with pretreated EGFR T790M mutation‐positive NSCLC whose screening EGFR T790M mutation‐positive status was determined from cytology samples. (ClinicalTrials.gov number NCT01802632).

Comparison of the Pharmacokinetics of the Phase II and Phase III Capsule Formulations of Selumetinib and the Effects of Food on Exposure: Results From Two Randomized Crossover Trials in Healthy Male Subjects

PURPOSE

Selumetinib (AZD6244, ARRY-142886), an oral, potent, and highly selective mitogen-activated protein kinase 1/2 inhibitor with a short half-life, has shown activity across various tumor types. Before initiation of Phase III trials, the site, scale, and color (hypromellose shell from white [Phase II] to blue [Phase III]) of the selumetinib 25mg capsule manufacture was changed. We present 2 crossover trials evaluating Phase III capsules in healthy subjects.

METHODS

The relative bioavailability trial was a Phase I, open-label, randomized, 3-treatment, 4-period, 6-sequence crossover trial in healthy male subjects (aged 18-55 years). Subjects received selumetinib 75mg (3 × 25 mg) Phase II or Phase III capsules, or a 35mg oral solution, during 4 dosing periods in 1 of 6 randomized treatment sequences. The food effect trial was a Phase I, open-label, randomized, 2-period crossover trial in healthy male subjects (aged 18-45 years). Subjects were randomized to 1 of 2 sequences to receive selumetinib 75mg (3 × 25 mg) Phase III capsules. In sequence 1, subjects received selumetinib after 10 hours of fasting. Following a washout period, selumetinib was administered after a high-fat meal. In sequence 2, subjects received selumetinib in the fed state, before the fasted state. Pharmacokinetic parameters were determined from serial blood sampling.

FINDINGS

Twenty-seven subjects were randomized to the relative bioavailability trial; 26 completed all dosing periods. Mean selumetinib AUC was unchanged (geometric least squares mean ratio [GLSMR], 90.01% [90% CI, 81.74-99.11]). C_max was 18% lower with the Phase III capsules (GLSMR, 81.97% [90% CI, 69.01-97.36]). A post hoc exploratory statistical analysis excluding outlying observations with later T_max showed that Phase II and III capsules produced similar exposure in terms of C_max and AUC. High intrasubject variability for C_max attributed to the pharmacokinetic sampling schedule was judged to have impacted on the estimated GLSMR. In the food effect trial, 34 subjects completed both study periods. A high-fat meal reduced selumetinib C_max compared with the fasted state (GLSMR, 49.76% [90% CI, 43.82-56.51]); AUC was minimally changed (GLSMR, 84.08% [90% CI, 80.72-87.59]). Median T_max was prolonged by 1.49 hours. No deaths or serious adverse events were reported.

IMPLICATIONS

Selumetinib 75mg (3 × 25 mg) Phase III capsules are being used in ongoing pivotal Phase III trials and should be administered in the fasted state. Based on findings from the relative bioavailability trial, pharmacokinetic sampling frequency was increased for healthy subject trials, including the food effect trial. ClinicalTrials.gov identifiers: NCT01635023 (relative bioavailability) and NCT01974349 (food effect).

Modulation of Biomarker Expression by Osimertinib: Results of the Paired Tumor Biopsy Cohorts of the AURA Phase I Trial

INTRODUCTION

Osimertinib is an oral, potent, irreversible EGFR tyrosine kinase inhibitor (TKI) selective for EGFR TKI and T790M resistance mutations. To enhance understanding of osimertinib's mechanism of action, we aimed to evaluate the modulation of key molecular biomarkers after osimertinib treatment in paired clinical samples from the phase I AURA trial.

METHODS

Paired tumor biopsy samples were collected before the study and after 15 plus or minus 7 days of osimertinib treatment (80 or 160 mg daily). Clinical efficacy outcomes were assessed according to whether viable paired biopsy samples could be collected; safety was also assessed. Immunohistochemical analyses assessed key pathway and tumor/immune-relevant markers (phospho-EGFR, phospho-S6, phospho-AKT, programmed death ligand 1, and CD8), with samples scored by image analysis or a pathologist blinded to treatment allocation.

RESULTS

Predose tumor biopsy samples were collected from 61 patients with EGFR T790M tumors; 29 patients had no viable postdose biopsy sample because of tumor regression or insufficient tumor sample. Evaluable predose and postdose tumor biopsy samples were collected from 24 patients. Objective response rate (ORR) and median progression-free survival (mPFS) were improved in patients from whom a postdose biopsy sample could not be collected (ORR 62% and mPFS 9.7 months [p = 0.027]) compared with those from whom paired samples were collected (ORR 29% and mPFS 6.6 months). Osimertinib modulated key EGFR signaling pathways and led to increased immune cell infiltration.

CONCLUSIONS

Collection of paired biopsy samples was challenging because of rapid tumor regression after osimertinib treatment, highlighting the difficulties of performing on-study biopsies in patients treated with highly active drugs.

CNS response to osimertinib in patients (pts) with T790M-positive advanced NSCLC: Data from a randomized phase III trial (AURA3)

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Background: CNS metastases (mets) are common in pts with advanced NSCLC. Preclinical studies have shown CNS penetration of osimertinib, and clinical data from a pooled analysis of 2 Phase II trials (AURA extension: NCT01802632, AURA2: NCT02094261) showed activity in the CNS. We report the first evidence of osimertinib efficacy in CNS mets from a randomized Phase III study (AURA3; NCT02151981) in pts with T790M-positive advanced NSCLC who have progressed on or after prior EGFR-TKI therapy. Methods: Pts were randomized 2:1 to osimertinib 80 mg once daily or platinum-based doublet chemotherapy every 3 wks for up to 6 cycles; maintenance pemetrexed was allowed. Pts with stable, asymptomatic CNS mets were eligible for enrolment. A prespecified subgroup analysis was conducted in pts with CNS mets present on baseline brain scan, as assessed by blinded independent central neuroradiology review (BICR), to define CNS objective response rate (ORR), duration of response (DoR) and progression-free survival (PFS) by RECIST v1.1. The CNS full analysis set (cFAS) included pts with ≥1 measurable and/or non-measurable CNS mets present on baseline brain scan by BICR; the CNS evaluable for response set (cEFR) included only pts with ≥1 measurable CNS mets. Results: As of 15 April 2016, 116/419 (28%) pts were included in the cFAS. In the cEFR (n = 46), CNS ORR was 70% (21/30; 95% CI 51, 85) with osimertinib and 31% (5/16; 95% CI 11, 59) with chemotherapy (OR, 5.13; 95% CI 1.44, 20.64; p = 0.015). In the cFAS, CNS ORR was 40% (30/75; 95% CI 29, 52) with osimertinib and 17% (7/41; 95% CI 7, 32) with chemotherapy (OR, 3.24; 95% CI 1.33, 8.81; p = 0.014). In the cEFR and cFAS, median CNS DoR was 8.9 months (m) (95% CI 4.3, NC and 4.3, NC) for osimertinib and 5.7 m (95% CI NC, NC and 4.4, 5.7; respectively) for chemotherapy. Median CNS PFS in the cFAS was significantly longer with osimertinib than with chemotherapy (11.7 vs 5.6 m; HR 0.32; 95% CI 0.15, 0.69; p = 0.004). Conclusions: Consistent with the overall response to osimertinib reported in pts with T790M-positive advanced NSCLC, osimertinib was superior to chemotherapy in the treatment of pts with CNS mets; CNS response rate was higher, responses were more durable and CNS PFS was longer. Clinical trial information: NCT02151981.

EGFR Mutation Analysis for Prospective Patient Selection in Two Phase II Registration Studies of Osimertinib

INTRODUCTION

Osimertinib is an oral, central nervous system-active, EGFR tyrosine kinase inhibitor (TKI) for the treatment of EGFR T790M-positive advanced NSCLC. Here we have evaluated EGFR mutation frequencies in two phase II studies of osimertinib (AURA extension and AURA2).

METHODS

After progression while receiving their latest line of therapy, patients with EGFR mutation-positive advanced NSCLC provided tumor samples for mandatory central T790M testing for the study selection criteria. Tumor tissue mutation analysis for patient selection was performed with the Roche cobas EGFR Mutation Test (European Conformity-in vitro diagnostic, labeled investigational use only) (Roche Molecular Systems, Pleasanton, CA). Patients should not have been prescreened for T790M mutation status. The cobas test results were compared with those of the MiSeq next-generation sequencing system (Illumina, San Diego, CA), which was used as a reference method.

RESULTS

Samples from 324 and 373 patients screened for AURA extension and AURA2, respectively, produced valid cobas test results. The T790M detection rates were similar between AURA extension and AURA2 (64% and 63%, respectively). The pooled T790M rate was 63%, with no difference by ethnicity (63% for Asian and non-Asian patients alike) or immediately prior treatment with an EGFR TKI (afatinib, 69%; erlotinib, 69%; and gefitinib, 63%). A higher proportion of patients had T790M detected against a background of exon 19 deletions versus L858R mutation (73% versus 58% [p = 0.0002]). In both trials the cobas test demonstrated high sensitivity (positive percent agreement) and specificity (negative percent agreement) for T790M detection when compared with the next-generation sequencing reference method: positive percent agreement of 91% versus 89% and negative percent agreement of 97% versus 98%.

CONCLUSIONS

In both trials, the rate of detection of T790M mutation in patients with advanced NSCLC was approximately 63% and was unaffected by immediately prior treatment with an EGFR TKI or ethnicity.

Osimertinib in Pretreated T790M-Positive Advanced Non-Small-Cell Lung Cancer: AURA Study Phase II Extension Component

Purpose Osimertinib is an irreversible epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) selective for both EGFR-TKI sensitizing ( EGFRm) and T790M resistance mutations. AURA (NCT01802632) is a phase I/II clinical trial to determine the dose, safety, and efficacy of osimertinib. This article reports the results from the phase II extension component. Patients and Methods Patients with EGFR-TKI-pretreated EGFRm- and T790M-positive advanced non-small-cell lung cancer (NSCLC) received once-daily osimertinib 80 mg. T790M status was confirmed by central testing from a tumor sample taken after the most recent disease progression. Patients with asymptomatic, stable CNS metastases that did not require corticosteroids were allowed to enroll. The primary end point was objective response rate (ORR) by independent radiology assessment. Secondary end points were disease control rate, duration of response, progression-free survival (PFS), and safety. Patient-reported outcomes comprised an exploratory objective. Results In total, 201 patients received treatment, with a median treatment duration of 13.2 months at the time of data cutoff (November 1, 2015). In evaluable patients (n = 198), ORR was 62% (95% CI, 54% to 68%), and the disease control rate was 90% (95% CI, 85 to 94). Median duration of response in 122 responding patients was 15.2 months (95% CI, 11.3 to not calculable). Median PFS was 12.3 months (95% CI, 9.5 to 13.8). The most common possibly causally related adverse events (investigator assessed) were diarrhea (43%; grade ≥ 3, < 1%) and rash (grouped terms; 40%; grade ≥ 3, < 1%). Interstitial lung disease (grouped terms) was reported in eight patients (4%; grade 1, n = 2; grade 3, n = 3; grade 5, n = 3). Conclusion In patients with EGFRm T790M advanced NSCLC who progress after EGFR-TKI treatment, osimertinib provides a high ORR, encouraging PFS, and durable response.

Plasma ctDNA Analysis for Detection of the EGFR T790M Mutation in Patients with Advanced Non-Small Cell Lung Cancer

INTRODUCTION

Tumor biopsies for detecting EGFR mutations in advanced NSCLC are invasive, costly, and not always feasible for patients with late-stage disease. The clinical utility of the cobas EGFR Mutation Test v2 (Roche Molecular Systems, Inc., Pleasanton, CA) with plasma samples from patients with NSCLC at disease progression after previous EGFR tyrosine kinase inhibitor therapy was investigated to determine eligibility for osimertinib treatment.

METHODS

Matched tumor tissue and plasma samples from patients screened for the AURA extension and AURA2 phase II studies were tested for EGFR mutations by using tissue- and plasma-based cobas EGFR mutation tests. Plasma test performance was assessed by using the cobas tissue test and a next-generation sequencing method (MiSeq [Illumina Inc., San Diego, CA]) as references. The objective response rate, measured by blinded independent central review, was assessed in patients receiving osimertinib with a plasma T790M mutation-positive status.

RESULTS

During screening, 551 patients provided matched tumor tissue and plasma samples. Pooled analysis of the positive and negative percent agreements between the cobas plasma and tissue tests for detection of T790M mutation were 61% and 79%, respectively. Comparing cobas plasma test with next-generation sequencing demonstrated positive and negative percent agreements of 90% or higher. The objective response rate was 64% (95% confidence interval: 57-70) in T790M mutation-positive patients by both cobas tissue and plasma tests (evaluable for response).

CONCLUSIONS

The cobas plasma test detected the T790M mutation in 61% of tumor tissue T790M mutation-positive patients. To mitigate the risk of false-negative plasma results, patients with a negative plasma result should undergo a tissue test where feasible.

Population pharmacokinetics and exposure-response of osimertinib in patients with non-small cell lung cancer

AIMS

To develop a population (pop) pharmacokinetic (PK) model for osimertinib (AZD9291) and its metabolite (AZ5104) and investigate the exposure-response relationships for selected efficacy and safety parameters.

METHODS

PK, safety and efficacy data were collected from two non-small cell lung cancer (NSCLC) patient studies (n = 748) and one healthy volunteer study (n = 32), after single or multiple once-daily dosing of 20-240 mg osimertinib. Nonlinear mixed effects modelling was used to characterise the popPK. Individual exposure values were used to investigate the relationship with response evaluation criteria in solid tumours (RECIST 1.1) efficacy parameters and key safety parameters (rash, diarrhoea, QTcF).

RESULTS

A popPK model that adequately described osimertinib and its metabolite AZ5104 in a joint manner was developed. Body weight, serum albumin and ethnicity were identified as significant covariates on PK in the analysis, but were not found to have a clinically relevant impact on osimertinib exposure. No relationship was identified between exposure and efficacy over the dose range studied. A linear relationship was observed between exposure and the occurrence of rash or diarrhoea, and between concentration and QTcF, with a predicted mean (upper 90% confidence interval) increase of 14.2 (15.8) ms at the maximum concentration for an 80 mg once-daily dose at steady state.

CONCLUSIONS

PopPK and exposure-response models were developed for osimertinib and AZ5104. There was no relationship between exposure and efficacy but a linear relationship between exposure and safety endpoints (rash, diarrhoea and QTcF) was observed.

Osimertinib for pretreated EGFR Thr790Met-positive advanced non-small-cell lung cancer (AURA2): a multicentre, open-label, single-arm, phase 2 study

BACKGROUND

Osimertinib (AZD9291) is an oral, potent, irreversible EGFR tyrosine-kinase inhibitor selective for EGFR tyrosine-kinase inhibitor sensitising mutations, and the EGFR Thr790Met resistance mutation. We assessed the efficacy and safety of osimertinib in patients with EGFR Thr790Met-positive non-small-cell lung cancer (NSCLC), who had progressed after previous therapy with an approved EGFR tyrosine-kinase inhibitor.

METHODS

In this phase 2, open-label, single-arm study (AURA2), patients aged at least 18 years with centrally confirmed EGFR Thr790Met-positive mutations, locally advanced or metastatic (stage IIIB/IV) NSCLC who progressed on previous EGFR tyrosine-kinase inhibitor therapy received osimertinib 80 mg orally once daily; treatment could continue beyond progression if the investigator observed a clinical benefit. Patients with asymptomatic, stable CNS metastases not requiring steroids were allowed to enrol. The primary endpoint was the proportion of patients achieving an objective response by blinded independent central review using Response Evaluation Criteria in Solid Tumors, version 1.1. Response endpoints were assessed in the evaluable for response analysis set (ie, all patients who received at least one dose of osimertinib and had measurable disease at baseline according to blinded independent central review). Other endpoints and safety were assessed in all patients receiving at least one osimertinib dose (full analysis set). The study is ongoing and patients are still receiving treatment. This study is registered with ClinicalTrials.gov, number NCT02094261.

FINDINGS

Between May 20, 2014, and Sept 12, 2014, 472 patients were screened, of whom 210 started osimertinib treatment between June 13, 2014, and Oct 27, 2014; 11 patients were excluded from the evaluable for response analysis set (n=199) due to absence of measurable disease at baseline by blinded independent central review. At data cutoff (Nov 1, 2015), 122 (58%) patients remained on treatment. The median duration of follow-up was 13·0 months (IQR 7·6-14·2). 140 (70%; 95% CI 64-77) of 199 patients achieved an objective response by blinded independent central review: confirmed complete responses were achieved in six (3%) patients and partial responses were achieved in 134 (67%) patients. The most common all-causality grade 3 and 4 adverse events were pulmonary embolism (seven [3%]), prolonged electrocardiogram QT (five [2%]), decreased neutrophil count (four [2%]), anaemia, dyspnoea, hyponatraemia, increased alanine aminotransferase, and thrombocytopenia (three [1%] each). Serious adverse events were reported in 52 (25%) patients, of which 11 (5%) were investigator assessed as possibly treatment-related to osimertinib. Seven deaths were due to adverse events; these were pneumonia (n=2), pneumonia aspiration (n=1), rectal haemorrhage (n=1), dyspnoea (n=1), failure to thrive (n=1), and interstitial lung disease (n=1). The only fatal event assessed as possibly treatment-related by the investigator was due to interstitial lung disease.

INTERPRETATION

Osimertinib showed clinical activity with manageable side-effects in patients with EGFR Thr790Met-positive NSCLC. Therefore, osimertinib could be a suitable treatment for patients with EGFR Thr790Met-positive disease who have progressed on an EGFR tyrosine-kinase inhibitor.

FUNDING

AstraZeneca.

Preclinical Comparison of Osimertinib with Other EGFR-TKIs in EGFR-Mutant NSCLC Brain Metastases Models, and Early Evidence of Clinical Brain Metastases Activity

PURPOSE

Approximately one-third of patients with non-small cell lung cancer (NSCLC) harboring tumors with EGFR-tyrosine kinase inhibitor (TKI)-sensitizing mutations (EGFRm) experience disease progression during treatment due to brain metastases. Despite anecdotal reports of EGFR-TKIs providing benefit in some patients with EGFRm NSCLC brain metastases, there is a clinical need for novel EGFR-TKIs with improved efficacy against brain lesions.

EXPERIMENTAL DESIGN

We performed preclinical assessments of brain penetration and activity of osimertinib (AZD9291), an oral, potent, irreversible EGFR-TKI selective for EGFRm and T790M resistance mutations, and other EGFR-TKIs in various animal models of EGFR-mutant NSCLC brain metastases. We also present case reports of previously treated patients with EGFRm-advanced NSCLC and brain metastases who received osimertinib in the phase I/II AURA study (NCT01802632).

RESULTS

Osimertinib demonstrated greater penetration of the mouse blood-brain barrier than gefitinib, rociletinib (CO-1686), or afatinib, and at clinically relevant doses induced sustained tumor regression in an EGFRm PC9 mouse brain metastases model; rociletinib did not achieve tumor regression. Under positron emission tomography micro-dosing conditions, [¹¹C]osimertinib showed markedly greater exposure in the cynomolgus monkey brain than [¹¹C]rociletinib and [¹¹C]gefitinib. Early clinical evidence of osimertinib activity in previously treated patients with EGFRm-advanced NSCLC and brain metastases is also reported.

CONCLUSIONS

Osimertinib may represent a clinically significant treatment option for patients with EGFRm NSCLC and brain metastases. Further investigation of osimertinib in this patient population is ongoing. Clin Cancer Res; 22(20); 5130-40. ©2016 AACR.

Association Between Plasma Genotyping and Outcomes of Treatment With Osimertinib (AZD9291) in Advanced Non-Small-Cell Lung Cancer

PURPOSE

Third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have demonstrated potent activity against TKI resistance mediated by EGFR T790M. We studied whether noninvasive genotyping of cell-free plasma DNA (cfDNA) is a useful biomarker for prediction of outcome from a third-generation EGFR-TKI, osimertinib.

METHODS

Plasma was collected from all patients in the first-in-man study of osimertinib. Patients who were included had acquired EGFR-TKI resistance and evidence of a common EGFR-sensitizing mutation. Genotyping of cell-free plasma DNA was performed by using BEAMing. Plasma genotyping accuracy was assessed by using tumor genotyping from a central laboratory as reference. Objective response rate (ORR) and progression-free survival (PFS) were analyzed in all T790M-positive or T790M-negative patients.

RESULTS

Sensitivity of plasma genotyping for detection of T790M was 70%. Of 58 patients with T790M-negative tumors, T790M was detected in plasma of 18 (31%). ORR and median PFS were similar in patients with T790M-positive plasma (ORR, 63%; PFS, 9.7 months) or T790M-positive tumor (ORR, 62%; PFS, 9.7 months) results. Although patients with T790M-negative plasma had overall favorable outcomes (ORR, 46%; median PFS, 8.2 months), tumor genotyping distinguished a subset of patients positive for T790M who had better outcomes (ORR, 69%; PFS, 16.5 months) as well as a subset of patients negative for T790M with poor outcomes (ORR, 25%; PFS, 2.8 months).

CONCLUSION

In this retrospective analysis, patients positive for T790M in plasma have outcomes with osimertinib that are equivalent to patients positive by a tissue-based assay. This study suggests that, upon availability of validated plasma T790M assays, some patients could avoid a tumor biopsy for T790M genotyping. As a result of the 30% false-negative rate of plasma genotyping, those with T790M-negative plasma results still need a tumor biopsy to determine presence or absence of T790M.

Osimertinib Western and Asian clinical pharmacokinetics in patients and healthy volunteers: implications for formulation, dose, and dosing frequency in pivotal clinical studies

PURPOSE

Osimertinib (AZD9291) 80 mg once daily is approved by the US FDA for the treatment of patients with metastatic EGFR T790M-positive NSCLC whose disease has previously progressed on EGFR-TKI therapy. Osimertinib PK was evaluated to define the dose and dosing interval, whether a fixed-dosing approach can be used globally, and the impact of formulation and food on exposure.

METHODS

AURA (NCT01802632): single- and multiple-dose PK of osimertinib (20-240 mg daily) was determined in patients with advanced NSCLC. Bioavailability study (NCT01951599): single-dose PK of osimertinib (20 mg) was determined in healthy volunteers with administration of capsule, solution, or tablet formulations fasted, and as a tablet in the fed and fasted state.

RESULTS

Osimertinib was slowly absorbed and displayed dose-proportional increases in exposure from 20 to 240 mg. Distribution was extensive and clearance low to moderate, resulting in a mean half-life of 48.3 h. Steady state was achieved by 15 days of dosing, consistent with single-dose PK, with a peak-to-trough ratio of 1.6. Two active metabolites circulated at ~10 % of osimertinib exposure. Ethnicity did not appear to affect exposure. Osimertinib PK profiles in healthy volunteers were similar to those in patients and were unaffected by formulation. Food caused a clinically insignificant increase in exposure.

CONCLUSIONS

Osimertinib PK supports once-daily dosing; the same dose for Asian and non-Asian populations; a fixed-dosing approach; a minimal effect of food on exposure; and a switch to tablet formulation without alteration to dose or schedule. Osimertinib plasma concentrations are sustained throughout the dosing period, which is considered optimal for efficacy.

EGFR mutation detection in ctDNA from NSCLC patient plasma: A cross-platform comparison of leading technologies to support the clinical development of AZD9291

OBJECTIVES

To assess the ability of different technology platforms to detect epidermal growth factor receptor (EGFR) mutations, including T790M, from circulating tumor DNA (ctDNA) in advanced non-small cell lung cancer (NSCLC) patients.

MATERIALS AND METHODS

A comparison of multiple platforms for detecting EGFR mutations in plasma ctDNA was undertaken. Plasma samples were collected from patients entering the ongoing AURA trial (NCT01802632), investigating the safety, tolerability, and efficacy of AZD9291 in patients with EGFR-sensitizing mutation-positive NSCLC. Plasma was collected prior to AZD9291 dosing but following clinical progression on a previous EGFR-tyrosine kinase inhibitor (TKI). Extracted ctDNA was analyzed using two non-digital platforms (cobas(®) EGFR Mutation Test and therascreen™ EGFR amplification refractory mutation system assay) and two digital platforms (Droplet Digital™ PCR and BEAMing digital PCR [dPCR]).

RESULTS

Preliminary assessment (38 samples) was conducted using all four platforms. For EGFR-TKI-sensitizing mutations, high sensitivity (78-100%) and specificity (93-100%) were observed using tissue as a non-reference standard. For the T790M mutation, the digital platforms outperformed the non-digital platforms. Subsequent assessment using 72 additional baseline plasma samples was conducted using the cobas(®) EGFR Mutation Test and BEAMing dPCR. The two platforms demonstrated high sensitivity (82-87%) and specificity (97%) for EGFR-sensitizing mutations. For the T790M mutation, the sensitivity and specificity were 73% and 67%, respectively, with the cobas(®) EGFR Mutation Test, and 81% and 58%, respectively, with BEAMing dPCR. Concordance between the platforms was >90%, showing that multiple platforms are capable of sensitive and specific detection of EGFR-TKI-sensitizing mutations from NSCLC patient plasma.

CONCLUSION

The cobas(®) EGFR Mutation Test and BEAMing dPCR demonstrate a high sensitivity for T790M mutation detection. Genomic heterogeneity of T790M-mediated resistance may explain the reduced specificity observed with plasma-based detection of T790M mutations versus tissue. These data support the use of both platforms in the AZD9291 clinical development program.

Abstract LB-123: Analysis of cell-free plasma DNA (cfDNA) identifies 3 molecular subtypes of acquired resistance to AZD9291, a novel EGFR tyrosine kinase inhibitor (TKI), in patients (pts) with advanced lung cancer

Introduction: EGFR T790M is the most common mechanism of acquired resistance to EGFR TKIs in pts with EGFR-mutant lung cancer. AZD9291 is an irreversible, mutant-selective EGFR TKI developed to have potency against both sensiziting EGFR mutations and T790M. In the ongoing phase I study of AZD9291 (AURA, NCT01802632), the response rate in pts with T790M-positive lung cancer was &gt;60%. The molecular mechanism underlying acquired resistance to AZD9291 is not known.

Methods & Results: To explore for mechanisms of resistance to AZD9291, we studied cfDNA extracted from pretreatment and post-progression plasma collected on AURA.Next-generation sequencing (NGS) of cfDNA was first performed on an exploratory cohort of 7 pts. All exons of a 20 gene panel (including EGFR) underwent PCR amplification and NGS using an Illumina HiSeq. In 1 pt, NGS of progression plasma identified a new EGFR C797S mutation in exon 20, not present in pretreatment plasma. Stable expression of C797S in Ba/F3 cells induced a &gt;100-fold increase in IC50 to AZD9291 compared to EGFR activating and T790M mutations alone. To validate the plasma NGS, digital droplet PCR (ddPCR) assays were developed to detect key EGFR mutations including C797S. 15 T790M-positive cases were identified with progression plasma available for analysis. Serial plasma ddPCR showed that both the EGFR activating and T790M mutation levels decreased with AZD9291 treament and increased at progression, with 3 molecular subtypes of resistance apparent. In 6 pts (40%), C797S was detected in addition to T790M; NGS of resistance biopsies from 2 of these pts confirmed presence of acquired C797S. In 5 pts (33%), T790M was detected without evidence of C797S. Intriguingly, in 4 pts (27%), the T790M levels became undetectable with treatment despite high levels of the EGFR activating mutation at progression, suggesting overgrowth of a competing non-T790M resistance mechanism. Further NGS of progression plasma revealed additional evidence of the genomic heterogeneity of resistance. Individual sequencing reads indicate that C797S and T790M can occur either in cis or in trans (i.e. on competing resistant alleles). In the 2 pts with tumor NGS demonstrating C797S, plasma NGS identified both the DNA alteration seen in tumor as well as a second DNA alteration encoding for C797S.

Conclusion: Using complementary assays for genomic analyses of cfDNA, we identified 3 molecular subtypes of acquired resistance to AZD9291, including an EGFR C797S mutation never before reported in pts. Due to the key role of the C797 residue in drug binding, C797S is expected to induce resistance to all irreversible EGFR TKIs currently in clinical development. Plasma NGS revealed substantial genomic heterogeneity and highlights the need for combination therapies to effectively prevent or treat drug resistance in cancer.

Citation Format: Geoffrey R. Oxnard, Kenneth S. Thress, Cloud P. Paweletz, Enriqueta Felip, Byoung Chul Cho, Daniel Stetson, Brian Dougherty, Zhongwu Lai, Aleksandra Morkovets, Ana Vivancos, Yanan Kuang, Dalia Ercan, Mireille Cantarini, J Carl Barrett, Pasi A. Janne. Analysis of cell-free plasma DNA (cfDNA) identifies 3 molecular subtypes of acquired resistance to AZD9291, a novel EGFR tyrosine kinase inhibitor (TKI), in patients (pts) with advanced lung cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-123. doi:10.1158/1538-7445.AM2015-LB-123

Acquired EGFR C797S mutation mediates resistance to AZD9291 in non-small cell lung cancer harboring EGFR T790M

Here we studied cell-free plasma DNA (cfDNA) collected from subjects with advanced lung cancer whose tumors had developed resistance to the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) AZD9291. We first performed next-generation sequencing of cfDNA from seven subjects and detected an acquired EGFR C797S mutation in one; expression of this mutant EGFR construct in a cell line rendered it resistant to AZD9291. We then performed droplet digital PCR on serial cfDNA specimens collected from 15 AZD9291-treated subjects. All were positive for the T790M mutation before treatment, but upon developing AZD9291 resistance three molecular subtypes emerged: six cases acquired the C797S mutation, five cases maintained the T790M mutation but did not acquire the C797S mutation and four cases lost the T790M mutation despite the presence of the underlying EGFR activating mutation. Our findings provide insight into the diversity of mechanisms through which tumors acquire resistance to AZD9291 and highlight the need for therapies that are able to overcome resistance mediated by the EGFR C797S mutation.

AZD9291 in EGFR inhibitor-resistant non-small-cell lung cancer

BACKGROUND

The EGFR T790M mutation is the most common mechanism of drug resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors in patients who have lung cancer with an EGFR mutation (EGFR-mutated lung cancer). In preclinical models, the EGFR inhibitor AZD9291 has been shown to be effective against both EGFR tyrosine kinase inhibitor-sensitizing and T790M resistance mutations.

METHODS

We administered AZD9291 at doses of 20 to 240 mg once daily in patients with advanced lung cancer who had radiologically documented disease progression after previous treatment with EGFR tyrosine kinase inhibitors. The study included dose-escalation cohorts and dose-expansion cohorts. In the expansion cohorts, prestudy tumor biopsies were required for central determination of EGFR T790M status. Patients were assessed for safety, pharmacokinetics, and efficacy.

RESULTS

A total of 253 patients were treated. Among 31 patients enrolled in the dose-escalation cohorts, no dose-limiting toxic effects occurred at the doses evaluated. An additional 222 patients were treated in five expansion cohorts. The most common all-cause adverse events were diarrhea, rash, nausea, and decreased appetite. The overall objective tumor response rate was 51% (95% confidence interval [CI], 45 to 58). Among 127 patients with centrally confirmed EGFR T790M who could be evaluated for response, the response rate was 61% (95% CI, 52 to 70). In contrast, among 61 patients without centrally detectable EGFR T790M who could be evaluated for response, the response rate was 21% (95% CI, 12 to 34). The median progression-free survival was 9.6 months (95% CI, 8.3 to not reached) in EGFR T790M-positive patients and 2.8 months (95% CI, 2.1 to 4.3) in EGFR T790M-negative patients.

CONCLUSIONS

AZD9291 was highly active in patients with lung cancer with the EGFR T790M mutation who had had disease progression during prior therapy with EGFR tyrosine kinase inhibitors. (Funded by AstraZeneca; ClinicalTrials.gov number, NCT01802632.).

AZD9291, an irreversible EGFR TKI, overcomes T790M-mediated resistance to EGFR inhibitors in lung cancer

First-generation EGFR tyrosine kinase inhibitors (EGFR TKI) provide significant clinical benefit in patients with advanced EGFR-mutant (EGFRm(+)) non-small cell lung cancer (NSCLC). Patients ultimately develop disease progression, often driven by acquisition of a second T790M EGFR TKI resistance mutation. AZD9291 is a novel oral, potent, and selective third-generation irreversible inhibitor of both EGFRm(+) sensitizing and T790M resistance mutants that spares wild-type EGFR. This mono-anilino-pyrimidine compound is structurally distinct from other third-generation EGFR TKIs and offers a pharmacologically differentiated profile from earlier generation EGFR TKIs. Preclinically, the drug potently inhibits signaling pathways and cellular growth in both EGFRm(+) and EGFRm(+)/T790M(+) mutant cell lines in vitro, with lower activity against wild-type EGFR lines, translating into profound and sustained tumor regression in EGFR-mutant tumor xenograft and transgenic models. The treatment of 2 patients with advanced EGFRm(+) T790M(+) NSCLC is described as proof of principle.

SIGNIFICANCE

We report the development of a novel structurally distinct third-generation EGFR TKI, AZD9291, that irreversibly and selectively targets both sensitizing and resistant T790M(+) mutant EGFR while harboring less activity toward wild-type EGFR. AZD9291 is showing promising responses in a phase I trial even at the first-dose level, with first published clinical proof-of-principle validation being presented.