Zhenfan Yang

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.

AZD3759, a BBB-penetrating EGFR inhibitor for the treatment of EGFR mutant NSCLC with CNS metastases

AZD3759 can penetrate the blood-brain barrier to treat EGFR mutant non–small-cell lung cancer with CNS metastases. Crossing the BBB to pursue tumors Non–small-cell lung cancer remains difficult to treat despite recent advances in targeted therapy. One reason for this is metastasis to the central nervous system. Drugs that inhibit the epidermal growth factor receptor (EGFR), a common target in this cancer, do not effectively penetrate the blood-brain barrier, which means that metastatic tumors can grow unchecked once they spread to the brain or spinal cord. Yang et al. have now developed a drug that not only can inhibit EGFR as effectively as clinically approved therapeutics but also can cross the blood-brain barrier to target metastases. This drug shows promising effectiveness in multiple different mouse models, as well as signs of antitumor activity in human patients. Non–small-cell lung cancer patients with activating mutations in epidermal growth factor receptor (EGFR) respond to EGFR tyrosine kinase inhibitor (TKI) treatment. Nevertheless, patients often develop central nervous system (CNS) metastases during treatment, even when their extracranial tumors are still under control. In the absence of effective options, much higher doses of EGFR TKIs have been attempted clinically, with the goal of achieving high enough drug concentrations within the CNS. Although limited tumor responses have been observed with this approach, the toxicities outside the CNS have been too high to tolerate. We report the discovery and early clinical development of AZD3759, a selective EGFR inhibitor that can fully penetrate the blood-brain barrier (BBB), with equal free concentrations in the blood, cerebrospinal fluid, and brain tissue. Treatment with AZD3759 causes tumor regression in subcutaneous xenograft, leptomeningeal metastasis (LM), and brain metastasis (BM) lung cancer models and prevents the development of BM in nude mice. An early clinical study in patients with BM and LM treated with AZD3759 confirms its BBB-penetrant properties and antitumor activities. Our data demonstrate the potential of AZD3759 for the treatment of BM and LM and support its further clinical evaluation in larger trials.

EGFR G796D mutation mediates resistance to osimertinib

Osimertinib is an effective third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) approved in multiple countries and regions for patients with EGFR T790M mutation-positive non-small cell lung cancer (NSCLC). Despite impressive initial tumor responses, development of drug resistance ultimately limits the benefit of this compound. Mechanisms of resistance to osimertinib are just beginning to emerge, such as EGFR C797S and L718Q mutations, BRAF V600E and PIK3CA E545K mutations, as well as ERBB2 and MET amplification. However, a comprehensive view is still missing. In this study, we presented the first case of Chinese NSCLC patient who developed resistance to osimertinib, and discovered de novo EGFR G796D mutation as a potential mechanism. Our findings provided insights into mechanisms of resistance to osimertinib and highlighted tumor heterogeneity and clonal evolution during the development of drug resistance.

Acquired MET Y1248H and D1246N mutations mediate resistance to MET inhibitors in non-small cell lung cancer

Purpose: MET amplification, responsible for 20% of acquired resistance to EGFR tyrosine kinase inhibitor (TKI) in patients with advanced non–small cell lung cancer (NSCLC), presents an attractive target. Numerous studies have conferred susceptibility of MET mutations and focal amplification to targeted MET-TKIs. However, the mechanism underlying MET-TKIs–induced resistance remains elusive. Experimental Design: We conducted a cohort of 12 patients with advanced NSCLC who developed resistance to a combinatorial therapy consisting of gefitinib and a type I MET-TKI. We performed capture-based targeted ultra-deep sequencing on serial tumor biopsies and plasmas ctDNA samples to detect and quantify genetic alterations. Results: We identified 2 newly acquired MET mutations, Y1248H and D1246N, in 2 patients and further confirmed their resistance against type I MET-TKIs in silco, in vitro, and in vivo. Interestingly, NIH3T3 cells harboring either mutation exhibited responses to type II MET-TKIs, suggesting sequential use of MET-TKIs may offer a more durable response. In addition, we also discovered that EGFR amplification may act as an alternative MET-TKI resistance mechanism. Conclusions: Our study provides insight into the diversity of mechanisms underlying MET-TKI–induced resistance and highlights the potential of sequential use of MET-TKIs. Clin Cancer Res; 23(16); 4929–37. ©2017 AACR.

Activity and safety of AZD3759 in EGFR-mutant non-small-cell lung cancer with CNS metastases (BLOOM): a phase 1, open-label, dose-escalation and dose-expansion study

BACKGROUND CNS metastases-including brain and leptomeningeal metastases-from epidermal growth factor receptor (EGFR)-mutant non-small-cell lung cancer (NSCLC) are associated with poor prognosis. AZD3759 is a novel EGFR tyrosine kinase inhibitor with high capability to penetrate the blood-brain barrier. We aimed to assess the safety, tolerability, pharmacokinetics, and efficacy of AZD3759 in patients with EGFR-mutant NSCLC with brain and leptomeningeal metastases. METHODS This open-label, multicentre, phase 1 study was undertaken at 11 centres and hospitals in Australia, South Korea, Taiwan, and the USA. Eligible patients included those with histologically confirmed, advanced-stage, EGFR-mutant NSCLC. The study was done in two parts, with dose-escalation and dose-expansion phases. In the dose-escalation phase, patients who had progressed after treatment with an EGFR tyrosine kinase inhibitor received AZD3759 at 50 mg, 100 mg, 200 mg, 300 mg, or 500 mg twice a day. In the dose-expansion phase, AZD3759 at 200 mg or 300 mg twice a day was administered to patients with either brain or leptomeningeal metastases who had never received an EGFR tyrosine kinase inhibitor and patients with leptomeningeal metastases who had been pretreated with an EGFR tyrosine kinase inhibitor. The primary objective was safety and tolerability, with severity of adverse events assessed with the National Cancer Institutes Common Terminology Criteria for Adverse Events, version 4.03. This trial is registered with ClinicalTrials.gov, number NCT02228369. FINDINGS Between Nov 18, 2014, and Sept 7, 2016, 67 patients with NSCLC were enrolled into the study, 29 to the dose-escalation phase and 38 to the dose-expansion phase. At data cutoff (Dec 12, 2016), three (10%) patients in the dose-escalation phase and 20 (53%) in the dose-expansion phase were still receiving treatment. Dose-limiting toxic effects occurred in two (67%) of three patients who received 500 mg twice a day in the dose-escalation phase (grade 3 acne [n=1] and intolerable grade 2 mucosal inflammation [n=1]); hence, doses of 200 mg and 300 mg twice a day were selected for further assessment in the dose-expansion phase. Drug-related skin and gastrointestinal disorders of any grade occurred in 35 (92%) and 29 (76%) patients in the dose-expansion phase, respectively, and led to treatment discontinuation in one (4%) patient treated with 200 mg twice a day (grade 3 increase of alanine aminotransferase and aspartate aminotransferase) and two (13%) patients given 300 mg twice a day (grade 3 diarrhoea [n=1] and grade 3 skin rash [n=1]). Grade 3 skin and gastrointestinal disorders occurred in four (17%) and two (9%) patients, respectively, at a dose of 200 mg twice a day, and in six (40%) and four (27%) patients, respectively, at a dose of 300 mg twice a day. No grade 4 disorders arose. Other grade 3 disorders included hepatobiliary and renal disorders (three [13%] at 200 mg twice a day), asthenia (one [7%] at 300 mg twice a day), infections and infestations (one [7%] at 300 mg twice a day), and metabolism and nutrition disorders (one [4%] at 200 mg twice a day and one [7%] at 300 mg twice a day). INTERPRETATION AZD3759 at a dose of 200 mg twice daily showed a tolerable safety profile in patients with NSCLC and CNS metastases who had either never received a tyrosine kinase inhibitor or who had been pretreated with a tyrosine kinase inhibitor. The good penetration of the blood-brain barrier by AZD3759, and its promising clinical activity, support further assessment of this compound in studies. FUNDING AstraZeneca.

Abstract A36: High T790M detection rate in TKI-naïve NSCLC with EGFR sensitive mutation: Truth or artifact?.

T790M in epidermal growth factor receptor (EGFR) accounts for about 50% of the acquired resistance to EGFR tyrosine kinase inhibitor (TKI) in patients with non-small cell lung cancer (NSCLC) carrying sensitive EGFR mutations. Earlier studies suggested that T790M mutation was also detected in about 2% of TKI-naive NSCLCs. Recently, three groups reported that, by using highly sensitive assays, T790M mutation was detected in about 40% of TKI-naive NSCLC with sensitive EGFR mutations. When we carefully studied these reports, we realized that all of those data were generated from formalin-fixed paraffin embedded (FFPE) tumor tissue samples, which raised a concern that the high mutation positivity could be consequence of formalin fixation. To address this, we assessed the T790M mutation in 36 pairs of frozen and FFPE tumor tissues of TKI-naive NSCLC with sensitive EGFR mutations using an enzyme-based mutant-enriched PCR assay (ME-PCR) with 0.1% sensitivity. In addition, frozen and FFPE adjacent normal tissues from the same patients were also assessed for a further comparison. While 41.7% (15/36) T790M positive rate was detected in the tumor FFPE samples which was consistent with previous reports, only 1 of the 36 (2.8%) frozen counterparts was T790M positive. As suspected, 48.5% (16/33) of T790M mutation rate was also identified in FFPE adjacent normal tissues but none of the 35 frozen adjacent normal tissues was T790M positive. Our results indicate that the high T790M positivity detected in TKI-naive NSCLC using some highly sensitive methods may in some cases be FFPE-derived artifacts. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A36. Citation Format: Xin Ye, Zhong-zheng Zhu, Lei Zhong, Yachao Lu, Yun Sun, Xiaolu Yin, Zhenfan Yang, Guanshan ZHU, Qunsheng Ji. High T790M detection rate in TKI-naive NSCLC with EGFR sensitive mutation: Truth or artifact?. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A36.

Heterogeneous responses and resistant mechanisms to crizotinib in ALK-positive advanced non-small cell lung cancer: Crizotinib resistance in ALK NSCLC

ALK‐tyrosine kinase inhibitors (TKIs) have been proven effective for treating ALK‐positive non‐small cell lung cancer (NSCLC), although patients present with variable responses and disease progression courses. The detailed underlying molecular mechanisms require further investigation to yield a better prognosis.

The brain-penetrant clinical ATM inhibitor AZD1390 radiosensitizes and improves survival of preclinical brain tumor models

Preclinical data highlight AZD1390 as a potentially powerful new therapy to enhance brain tumor patient responses to radiotherapy. Poor survival rates of patients with tumors arising from or disseminating into the brain are attributed to an inability to excise all tumor tissue (if operable), a lack of blood-brain barrier (BBB) penetration of chemotherapies/targeted agents, and an intrinsic tumor radio-/chemo-resistance. Ataxia-telangiectasia mutated (ATM) protein orchestrates the cellular DNA damage response (DDR) to cytotoxic DNA double-strand breaks induced by ionizing radiation (IR). ATM genetic ablation or pharmacological inhibition results in tumor cell hypersensitivity to IR. We report the primary pharmacology of the clinical-grade, exquisitely potent (cell IC50, 0.78 nM), highly selective [>10,000-fold over kinases within the same phosphatidylinositol 3-kinase–related kinase (PIKK) family], orally bioavailable ATM inhibitor AZD1390 specifically optimized for BBB penetration confirmed in cynomolgus monkey brain positron emission tomography (PET) imaging of microdosed 11C-labeled AZD1390 (Kp,uu, 0.33). AZD1390 blocks ATM-dependent DDR pathway activity and combines with radiation to induce G2 cell cycle phase accumulation, micronuclei, and apoptosis. AZD1390 radiosensitizes glioma and lung cancer cell lines, with p53 mutant glioma cells generally being more radiosensitized than wild type. In in vivo syngeneic and patient-derived glioma as well as orthotopic lung-brain metastatic models, AZD1390 dosed in combination with daily fractions of IR (whole-brain or stereotactic radiotherapy) significantly induced tumor regressions and increased animal survival compared to IR treatment alone. We established a pharmacokinetic-pharmacodynamic-efficacy relationship by correlating free brain concentrations, tumor phospho-ATM/phospho-Rad50 inhibition, apoptotic biomarker (cleaved caspase-3) induction, tumor regression, and survival. On the basis of the data presented here, AZD1390 is now in early clinical development for use as a radiosensitizer in central nervous system malignancies.

Prospective study revealed prognostic significance of responses in leptomeningeal metastasis and clinical value of cerebrospinal fluid-based liquid biopsy

OBJECTIVE Leptomeningeal metastasis (LM) secondary to non-small cell lung cancer (NSCLC) is a devastating complication associated with poor prognosis. Diagnosis and assessment of responses in LM have been challenging due to limitation of traditional imaging tools and lack of standard evaluation criteria until very recently. To bridge this gap, we conducted the first prospective, observational study in cytologically diagnosed NSCLC-LM patients (NCT02803619). PATIENTS AND METHODS A total of 49 NSCLC-LM patients were enrolled. LM responses were evaluated with a composite endpoint integrating neurological symptoms, cerebrospinal fluid (CSF) parameters and central nervous system (CNS) imaging. Primary outcome was overall survival (OS) after diagnosis of LM. Exploratory endpoint was the association between OS and prognostic factors. Primary tumor and CSF samples were collected for biomarker analysis. RESULTS 93.9% of the cohort carried oncogenic drivers, and 85.7% harbored EGFR activating mutations. Median OS since LM diagnosis of the overall population was 9.7 months. EGFR mutant LM patients had a longer survival compared with wildtype ones. LM clinical responses assessed by the composite endpoint showed significant correlation with OS. Status of EGFR activating mutations was highly concordant between primary tumor and CSF. T790 M occurrence in CNS lesions was relatively rare and associated with intracranial exposure level of EGFR-TKIs. CONCLUSION Our results supported the composite endpoint for objective response evaluation of LM was valid, suggested LM outweighed peripheral lesions on the impact to patient survival, and emphasized the urge and promise of development of CNS-penetrant targeted therapies to improve clinical outcome of NSCLC-LM patients.

EGFR L792H and G796R: Two Novel Mutations Mediating Resistance to the Third-Generation EGFR Tyrosine Kinase Inhibitor Osimertinib

Background: The third‐generation EGFR tyrosine kinase inhibitor osimertinib has been approved in many countries to treat advanced NSCLC in patients with the EGFR T790M mutation. As the development of acquired resistance is inevitable, it is urgent that the mechanisms of such resistance be clarified. Methods: DNA samples from a cohort of 340 patients with lung adenocarcinoma who were taking osimertinib were subjected to next‐generation sequencing and screened in terms of the frequencies of the L792H and G796R mutations. Ba/F3 cells stably expressing the EGFR L858R/T790M mutations (in cis) with either the L792H or G796R mutation were created to investigate the impact of the two novel mutations on EGFR tyrosine kinase inhibitors and other potential drug combinations in vitro. Structural analyses were performed by using Schrödinger/Maestro software (version 11.1.012, Schrödinger LLC, Cambridge, MA). Results: L792H and G796R were detected in 1.76% (six of 340) and 0.56% (two of 340) patients with lung adenocarcinoma treated with osimertinib, respectively. The introduction of L792H or G796R mutations against an L858R/T790M background caused dramatic reductions in osimertinib sensitivity. Structural modeling showed that mutations in cis with T790M either forced the ligand (osimertinib) to rotate out (breaking the binding) or pulled the hinge loop (breaking the hinge). Various other drug combinations. including cetuximab with EAI045, failed to inhibit either cis mutant effectively. Conclusions: The EGFR L858R/T790M/L792H and L858R/T790M/G796R mutations conferred resistance to osimertinib both in vitro and in silico. For patients in whom the two resistance mutations occur at low frequency, more precise treatment strategies and additional combinational approaches are required.