Combination Of Osimertinib Research Articles

Osimertinib and dihydroartemisinin: a novel drug combination targeting head and neck squamous cell carcinoma.

Recurrent and metastatic head and neck squamous cell carcinoma (HNSCC) has a dismal prognosis with limited progression-free survival and overall survival, even when treated with different combinations of chemotherapy, targeted therapies and immunotherapy. We explored in vitro and in vivo the effect of the epidermal growth factor receptor (EGFR) inhibitor, osimertinib, alone and in combination with dihydroartemisinin (DHA) in HNSCC. The combination of osimertinib with DHA was tested in the FaDu and CAL27 HNSCC cell lines. Tumor cell proliferation assays were conducted in cultured cells and mouse xenografts. Western blotting analysis of related signal pathways was performed to investigate the molecular mechanisms of the inhibitory effect of DHA and the combination. Other compounds, which inhibit signal transducer and activator of transcription 3 (STAT3), Src-family kinases (SFKs), sphingosine kinase 1 (SPHK1), or the receptor tyrosine kinase (RTK) AXL were also combined with osimertinib in vitro. Osimertinib exerted synergistic cytotoxicity toward FaDu and CAL27 HNSCC cells when combined with DHA. DHA reversed the osimertinib-induced STAT3 and Src phosphorylation. The double combination inhibited AXL expression. The anticancer potential of osimertinib plus DHA combination was validated in vivo on FaDu and CAL27 xenografts in mice without notable side effects. The results illustrate that the combinatory therapy of osimertinib and DHA, as a repurposing anticancer drug, could be a novel therapeutic strategy for recurrent and/or metastatic HNSCC patients. The findings strongly indicate that a clinical trial is warranted to confirm the benefit of the combination.

PhIb Study Evaluating Safety and Efficacy of Combination Osimertinib and Ipilimumab in Patients w EGFR Mutated NSCLC

PhIb Study Evaluating Safety and Efficacy of Combination Osimertinib and Ipilimumab in Patients w EGFR Mutated NSCLC

Novel treatment strategies for EGFR mutant lung cancer

Abstract Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are the standard of care for patients with advanced EGFR mutant non-small cell lung cancer (NSCLC). Osimertinib, a mutant selective EGFR TKI, when used as initial therapy, results in median progression free survival (PFS) of 18.9 months. However, all patients ultimately develop resistance to osimertinib and new strategies to enhance the initial efficacy of osimertinib or treat acquired resistance mechanisms are needed. Acquired resistance to osimertinib is heterogenous and can be mediated by both on-target resistance mechanisms (EGFR C797S) or activation of parallel (MET or HER2 amplification or acquired oncogenic rearrangements) or downstream (KRAS or BRAF mutations) signaling pathways. Strategies to treat these resistance mechanisms include 1st/2nd generation EGFR inhibitors or concomitant targeting of the activated signaling pathway. Novel treatment approaches including the development of allosteric EGFR inhibitors and more comprehensive means of targeting resistance using a HER3 antibody drug conjugate (ADC; U3-1402) will be discussed. A complementary approach is to enhance the initial efficacy of osimertinib. Preclinical studies demonstrate that reactivation of ERK 1/2 signaling occurs within just a few days of osimertinib treatment. EGFR inhibitor mediated apoptosis requires upregulation of the proapoptotic protein BIM and this process is controlled by ERK 1/2 signaling. Thus ERK 1/2 reactivation following osimertinib treatment decouples EGFR inhibition from apoptosis. Concomitant EGFR and MEK inhibition prevents this process and leads to a greater apoptotic response than osimertinib alone. Strategies to translate these observations and other first line osimertinib combination studies will be discussed.

Impact of apatinib in combination with osimertinib on EGFR T790M-positive lung adenocarcinoma

Background: The purpose of this study was to investigate the anti-tumor activities and the mechanisms of the third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) osimertinib, combined with the anti-angiogenic target drug apatinib, in the treatment of lung adenocarcinoma. We investigated the effects of these drugs in vitro in PC9 (E19 del) and H1975 (E21 L858R/E20 T790M) cell lines, as well as in vivo in both mouse and human experiments. Methods: PC9 and H1975 cells were cultured in 96-well plates and incubated with osimertinib (1–100 nmol/L), or apatinib (100–1,000 nmol/L), or a combination of the two agents, for 48 h. Cell viability was determined using a Cell Counting Kit-8. The protein expression of EGFR and its downstream signaling pathway members (AKT and ERK) was detected by western blot. For in vivo experiments, BALB/c nude mice were subcutaneously inoculated with H1975 cells in a xenograft model of adenocarcinoma. Mice bearing tumors were treated with osimertinib alone or in combination with apatinib, and tumor growth curves were obtained. Furthermore, we evaluated the efficacy and safety of combined osimertinib and apatinib therapy in three patients with EGFR T790M positive lung adenocarcinoma, who had been previously sensitized to osimertinib but developed an acquired resistance. Results: In vitro experiments revealed that osimertinib combined with apatinib increased the growth inhibition of PC9 and H1975 cells, simultaneously reducing the protein expression of phosphorylated EGFR and its downstream signaling pathway members in H1975 cells, compared to osimertinib treatment alone. In vivo experiments revealed that the combination of osimertinib and apatinib decreased tumor volume in an H1975 cell xenograft model, compared to osimertinib monotherapy at different dosages. All three patients with T790M positive lung adenocarcinoma that progressed following osimertinib treatment responded to continuous osimertinib in combination with apatinib, with a progression-free survival (PFS) range of 5–7 months. Conclusions: Apatinib can enhance the anti-tumor activity of osimertinib in the treatment of T790M positive lung adenocarcinoma. Further clinical studies are needed to confirm these results.

Exon 16-Skipping HER2 as a Novel Mechanism of Osimertinib Resistance in EGFR L858R/T790M-Positive Non-Small Cell Lung Cancer.

Osimertinib is the current recommended treatment for EGFR T790M-positive NSCLC after EGFR tyrosine kinase inhibitor therapy. However, resistance to osimertinib therapy is inevitably acquired after a period of effective treatment. We had a patient with EGFR L858R/T790M-positive NSCLC who initially responded to osimertinib therapy but eventually experienced development of resistance. Plasma cell-free DNA analysis revealed the occurrence of exon 16-skipping HER2, which may have resulted in the erb-b2 receptor tyrosine kinase 2 gene (HER2) splice variant HER2D16. HER2D16 has never been reported in lung cancer, and HER2D16-driven signaling is known to be regulated by Src kinase in breast cancer. We investigated the role of HER2D16 as an osimertinib-resistant mechanism. We constructed and established H1975 cells stably expressing HER2D16. The dimeric formation of HER2D16 was tested by using nonreducing polyacrylamide gel electrophoresis. The effects of the study drugs on signaling transduction were examined by using Western blot. Synergistic effect was assessed by using the Chou-Talalay method. We found that HER2D16 can form a homodimer in NSCLC cells. HER2D16-expressing H1975 cells were resistant to osimertinib treatment. We also found that mutant EGFR and HER2D16 cooperated to activate downstream signaling for osimertinib resistance. In addition, cotreatment with osimertinib and an Src kinase inhibitor failed toreverse resistance, indicating that HER2D16-driven signaling in NSCLC did not occur through a canonical pathway. Finally, we revealed that the combination of osimertinib with the pan-HER small-molecule inhibitor afatinib could synergistically repress cell growth and signaling in H1975-HER2D16 cells. HER2D16 can contribute to osimertinib resistance through an Src-independent pathway. HER2D16 should be included in the molecular diagnosis panel for lung cancer.

Impact of apatinib in combination with osimertinib on EGFR T790M-positive lung adenocarcinoma.

BackgroundThe purpose of this study was to investigate the anti-tumor activities and the mechanisms of the third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) osimertinib, combined with the anti-angiogenic target drug apatinib, in the treatment of lung adenocarcinoma. We investigated the effects of these drugs in vitro in PC9 (E19 del) and H1975 (E21 L858R/E20 T790M) cell lines, as well as in vivo in both mouse and human experiments.MethodsPC9 and H1975 cells were cultured in 96-well plates and incubated with osimertinib (1–100 nmol/L), or apatinib (100–1,000 nmol/L), or a combination of the two agents, for 48 h. Cell viability was determined using a Cell Counting Kit-8. The protein expression of EGFR and its downstream signaling pathway members (AKT and ERK) was detected by western blot. For in vivo experiments, BALB/c nude mice were subcutaneously inoculated with H1975 cells in a xenograft model of adenocarcinoma. Mice bearing tumors were treated with osimertinib alone or in combination with apatinib, and tumor growth curves were obtained. Furthermore, we evaluated the efficacy and safety of combined osimertinib and apatinib therapy in three patients with EGFR T790M positive lung adenocarcinoma, who had been previously sensitized to osimertinib but developed an acquired resistance.ResultsIn vitro experiments revealed that osimertinib combined with apatinib increased the growth inhibition of PC9 and H1975 cells, simultaneously reducing the protein expression of phosphorylated EGFR and its downstream signaling pathway members in H1975 cells, compared to osimertinib treatment alone. In vivo experiments revealed that the combination of osimertinib and apatinib decreased tumor volume in an H1975 cell xenograft model, compared to osimertinib monotherapy at different dosages. All three patients with T790M positive lung adenocarcinoma that progressed following osimertinib treatment responded to continuous osimertinib in combination with apatinib, with a progression-free survival (PFS) range of 5–7 months.ConclusionsApatinib can enhance the anti-tumor activity of osimertinib in the treatment of T790M positive lung adenocarcinoma. Further clinical studies are needed to confirm these results.

Osimertinib and Dihydroartemisinin: A Novel Drug Combination Targeting Head and Neck Squamous Cell Carcinoma

Background: Recurrent and metastatic head and neck squamous cell carcinoma (HNSCC) has a dismal prognosis with limited progressionfree survival and overall survival, even when treated with different combinations of chemotherapy, targeted therapies and immunotherapy. We explored in vitro and in vivo the effect of the epidermal growth factor (EGFR) inhibitor, osimertinib, alone and in combination with dihydroartemisinin (DHA) in HNSCC. Methods: The combination of osimertinib with DHA was tested in the FaDu and CAL27 HNSCC cell lines. Tumor cell proliferation assays were conducted in cultured cells and mouse xenografts. Western blotting analysis of related signal pathways was performed to investigate the molecular mechanisms of the inhibitory effect of DHA and the combination. Other compounds, which inhibit signal transducer and activator of transcription 3 (STAT3), Src-family kinases (SFKs), sphingosine kinase 1 (SPHK1), or the receptor tyrosine kinase (RTK) AXL were also combined with osimertinib in vitro. Results: Osimertinib exerted synergistic cytotoxicity toward FaDu and CAL27 HNSCC cells when combined with DHA. DHA reversed the osimertinibinduced STAT3 and Src phosphorylation. The double combination inhibited AXL expression. The anticancer potential of osimertinib plus DHA combination was validated in vivo on FaDu and CAL27 xenografts in mice with significant tumor regression. Interpretation: The results illustrate that the combinatory therapy of osimertinib and DHA, as a repurposing anticancer drug, could be a novel therapeutic strategy for recurrent and/or metastatic HNSCC patients. The findings strongly indicate that a clinical trial is warranted to confirm the benefit of the combination. Funding Statement: Work in Dr. Rosell's laboratory is partially supported by a grant from La Caixa Foundation, an Instituto de Salud Carlos III grant (RESPONSE, PIE16/00011), an Instituto de Salud Carlos III grant (PI14/01678), a Marie Sklodowska-Curie Innovative Training Networks European Grant (ELBA No 765492) and a Spanish Association Against Cancer (AECC) grant (PROYE18012ROSE). Work in Dr. Cao's laboratory is partially supported by the Major National Science and Technology Program of China for Innovative Drug (2017ZX09101002-002-006), the Priority Academic Program Development of Jiangsu Higher Education Institutions (Integration of Chinese and Western Medicine) grant and Key R&D Program of Jiangsu Province (BE2018755). Declaration of Interests: The authors declare no potential conflicts of interest. Ethics Approval Statement: All procedures were based on Guide for Care and Use of Laboratory Animals of National Institutes of Health and approved by Institutional Animal Care and Use Committee of Jiangsu Province Academy of Traditional Chinese Medicine (SYXK 2016-0018).

Degradation of MCL-1 by bufalin reverses acquired resistance to osimertinib in EGFR-mutant lung cancer

Although osimertinib, an EGFR tyrosine kinase inhibitor, has become the standard therapy for treating non-small cell lung cancer (NSCLC) patients with EGFR-activating mutation, upregulation of MCL-1 induces acquired resistance to osimertinib. Bufalin, a natural digoxin-like ingredient isolated from a traditional Chinese medicine Chan Su, has been shown to downregulate MCL-1 in NSCLC cells. However, whether bufalin reverses this acquired resistance to osimertinib in NSCLC cells remains unclear. In this study, bufalin reduced cell viability and promoted apoptosis in osimertinib-resistant cells. Moreover, co-treatment with bufalin and osimertinib restored the sensitivity of osimertinib-resistant cells to osimertinib-induced growth regression and apoptosis in vitro and in vivo. Mechanistically, MEK/ERK-dependent MCL-1 phosphorylation and Ku70-mediated MCL-1 overexpression confer osimertinib resistance in EGFR-mutant NSCLC cells. In osimertinib-resistant cells, bufalin modulates Ku70-mediated MCL-1 degradation, but not MEK/ERK/MCL-1 signaling. In conclusion, our study suggests that bufalin eliminates resistance to osimertinib by inhibiting Ku70-mediated MCL-1 overexpression, indicating that a combination of osimertinib and bufalin could be an effective additional treatment to overcome acquired resistance to osimertinib in NSCLC cells.

Abstract 4752: Exon-16-skipping HER2 contributes to osimertinib-resistance through Src-independent manner in EGFRL858R/T790M-positive non-small-cell lung cancer

Abstract Osimertinib is current recommended treatment for EGFR T790M-positive NSCLC following progression on prior EGFR tyrosine kinase inhibitor therapy. However, acquired resistance to osimertinib therapy inevitably developed after a period of effective treatment. We had a patient of EGFR L858R/T790M-positive NSCLC who initially responded to osimertinib therapy but eventually developed resistance. Plasma cell-free DNA analysis disclosed exon-16-skipping HER2 (HER2Δ16) in one osimertinib treated patient. HER2Δ16 was regarded as an oncogenic driver in breast cancer and has never been reported in lung cancer before. Therefore, it’s intriguing to investigate the role of HER2Δ16 in osimertinib resistance in NSCLC. The purpose of this study is to explore the mechanism of HER2Δ16-mediated resistance to osimertinib and to explore strategies to overcome the resistance. We constructed and established H1975 cells stably expressing either vehicle, WT-HER2 or HER2Δ16. We observed that without osimertinib treatment, there was no difference in cell growth and the response to EGF-stimulation. However, when treated with osimertinib, H1975-HER2Δ16 cells were more resistant under normal and EGF-stimulating conditions compared to vehicle or WT-HER2 expressing cells. Moreover, osimertinib treatment in H1975-HER2Δ16 cells had less inhibitory effect on phosphor-ERK and phosphor-AKT compared to vehicle or H1975-WT-HER2 cells. Interestingly, co-treatment of osimertinib with Src-kinase inhibitor, dasatinib, failed to reverse the resistance, indicating that HER2Δ16-driven osimertinib-resistance was independent of Src-kinase. Finally, we revealed that combination of osimertinib with the HER2 small molecular inhibitor, afatinib, can suppress cell growth in H1975-WT-HER2 and H1975-HER2Δ16 cells. In summary, we have shown that HER2Δ16, may be a resistance mechanism to osimertinib in EGFR mutated NSCLC and that HER2Δ16-driven resistance was Src-kinase independent. Moreover, we found the HER2Δ16-driven resistance could be rescued by combination of osimertinib with afatinib. Citation Format: Chia-Chi Hsu, Bin-Chi Liao, Wei-Yu Liao, Aleksandra Markovets, Daniel Stetson, Kenneth Thress, Chih-Hsin Yang. Exon-16-skipping HER2 contributes to osimertinib-resistance through Src-independent manner in EGFRL858R/T790M-positive non-small-cell lung cancer [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 4752.

Abstract 4762: Activation of AXL as a preclinical acquired resistance mechanism against osimertinib treatment in EGFR-mutant non-small cell lung cancer cells

Abstract Osimertinib (AZD9291) has an efficacy superior to that of standard EGFR-tyrosine kinase inhibitors for the first-line treatment of EGFR-mutant advanced non-small cell lung cancer (NSCLC) patients. However, patients treated with osimertinib eventually acquire drug resistance, and novel therapeutic strategies to overcome acquired resistance are needed. In clinical or preclinical models, several mechanisms of acquired resistance to osimertinib have been elucidated. However, the acquired resistance mechanisms when osimertinib is initially used for EGFR-mutant NSCLC remain unclear. In this study, we experimentally established acquired osimertinib-resistance cell lines from EGFR-mutant NSCLC cell lines and investigated the molecular profiles of resistant cells to uncover the mechanisms of acquired resistance. Various resistance mechanisms were identified, including the acquisition of MET amplification, EMT induction, and the upregulation of AXL. Using targeted next-generation sequencing with a multi-gene panel, no secondary mutations were detected in our resistant cell lines. Among three MET-amplified cell lines, one cell line was sensitive to a combination of osimertinib and crizotinib. Acquired resistance cell lines derived from H1975 harboring the T790M mutation showed AXL upregulation, and the cell growth of these cell lines was suppressed by a combination of osimertinib and cabozantinib, an inhibitor of multiple tyrosine kinases including AXL, both in vitro and in vivo. Our results suggest that AXL might be a therapeutic target for overcoming acquired resistance to osimertinib. Citation Format: Kei Namba, Kazuhiko Shien, Yuta Takahashi, Hiroki Sato, Takahiro Yoshioka, Ken Suzawa, Hiromasa Yamamoto, Junichi Soh, Shuta Tomida, Shinichi Toyooka. Activation of AXL as a preclinical acquired resistance mechanism against osimertinib treatment in EGFR-mutant non-small cell lung cancer cells [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 4762.

Chloroquine sensitizes MDA-MB-231 cells to osimertinib through autophagy-apoptosis crosstalk pathway.

Background: Triple-negative breast cancer (TNBC) is a breast cancer that tests negative for estrogen receptor (ER), progesterone receptors, and human epidermal growth factor receptors 2 (HER2). It is aggressive and invasive in nature and lacks targeted therapy.Purpose: The EGFR is frequently overexpressed in TNBC, and the EGFR-overexpressing TNBC presumably escapes EGFR inhibitor therapy by upregulating autophagy and inhibiting apoptosis.Methods: To parse the autophagy–apoptosis crosstalk pathway as a potential targeted therapy in TNBC, the activity of an EGFR inhibitor, osimertinib, alone and in combination with an autophagy inhibitor, chloroquine, was examined in EGFR-overexpressing TNBC cell line, MDA-MB-231. The nature of interaction between both drugs at various concentrations was determined by calculating combination indexes (CI) using CompuSyn software. Temporal changes in the expression of the autophagy marker, LC3B-II, and several apoptosis signaling molecules were measured using Western blot and luminex assay with MAGPIX® after exposure to drugs. A synergistic interaction (CI <1) was identified with combinations of 4–6.5 μM osimertinib with 30–75 μM chloroquine.Results: A combination of osimertinib (6 μM) with chloroquine (30 μM) resulted in a 6-fold increase of LC3B-II relative to control compared to 2.5-fold increase for either drug alone. The caspase-3 expression increased 2-fold compared to a 0.5-fold decrease with chloroquine and 1.5-fold increase with osimertinib.Conclusion: Our results indicate that inhibition of the autophagic flux via chloroquine improves the effectiveness of osimertinib in TNBC cancer cells, warranting further investigations of this combination in vivo.

Single and Dual Targeting of Mutant EGFR with an Allosteric Inhibitor.

Allosteric kinase inhibitors offer a potentially complementary therapeutic strategy to ATP-competitive kinase inhibitors due to their distinct sites of target binding. In this study, we identify and study a mutant-selective EGFR allosteric inhibitor, JBJ-04-125-02, which as a single agent can inhibit cell proliferation and EGFRL858R/T790M/C797S signaling in vitro and in vivo. However, increased EGFR dimer formation limits treatment efficacy and leads to drug resistance. Remarkably, osimertinib, an ATP-competitive covalent EGFR inhibitor, uniquely and significantly enhances the binding of JBJ-04-125-02 for mutant EGFR. The combination of osimertinib and JBJ-04-125-02 results in an increase in apoptosis, a more effective inhibition of cellular growth, and an increased efficacy in vitro and in vivo compared with either single agent alone. Collectively, our findings suggest that the combination of a covalent mutant-selective ATP-competitive inhibitor and an allosteric EGFR inhibitor may be an effective therapeutic approach for patients with EGFR-mutant lung cancer. SIGNIFICANCE: The clinical efficacy of EGFR tyrosine kinase inhibitors (TKI) in EGFR-mutant lung cancer is limited by acquired drug resistance, thus highlighting the need for alternative strategies to inhibit EGFR. Here, we identify a mutant EGFR allosteric inhibitor that is effective as a single agent and in combination with the EGFR TKI osimertinib.This article is highlighted in the In This Issue feature, p. 813.

Abstract 4897: Detection of MET-mediated EGFR tyrosine kinase inhibitor (TKI) resistance in advanced non-small cell lung cancer (NSCLC): biomarker analysis of the TATTON study

Abstract EGFR-TKIs like osimertinib are widely used to treat advanced EGFR-mutant NSCLC, however tumors inevitably acquire resistance. Amplification of MET occurs in ~20% of EGFR-TKI resistant tumors. Previous studies have used a variety of technologies (FISH, IHC, NGS, ctDNA) with mixed success in identifying MET-driven tumors. Thus, there is an urgent need to better understand the reliability of these assays for the detection of MET-driven EGFR-TKI resistance in NSCLC. In the TATTON study (NCT02143466), the combination of osimertinib and savolitinib (AZD6094, HMPL-504, volitinib), a potent and selective MET-TKI, has demonstrated encouraging anti-tumor activity in patients with NSCLC and MET-driven EGFR-TKI resistance. During screening, MET testing (central, or local with central confirmation) was performed on tumor tissue collected after the most recent therapy. Informative central MET FISH screening/confirmation results were generated for 254 consented patients. MET overexpression and amplification were further assayed centrally using tissue IHC (n=81), tissue NGS (n=117; Foundation Medicine), and ctDNA NGS (n=199; Guardant Health). Standard NGS provider MET amplification calls were used. Central IHC positivity was defined as 3+ in ≥50% of tumor cells. Central FISH+ was defined as either amplification (MET:CEP7 ratio ≥2) or polysomy (gene copy number ≥5 if MET:CEP7 &amp;lt;2). MET FISH was used as the common comparator across assays. Central MET FISH+ was found in 123/254 tumors (48%; 75 with amplification, 48 with polysomy), an elevated prevalence likely related to local MET+ prescreening. Comparison of tissue NGS with FISH (n=95) identified high negative-percent agreement (NPA, 98%) but modest positive-percent agreement (PPA, 48%). Further investigation indicated NGS PPA is highly dependent on the FISH result, with higher PPA for amplification (88%) but low PPA for polysomy (4%). Similarly, comparison of ctDNA NGS with FISH (n=112) yielded modest NPA (90%) and PPA of only 25% (43% for amplification; 10% for polysomy). PPA improved to 50% (64% for amplification; 30% for polysomy) when limited to 46 patients with an EGFR mutation detected at &amp;gt;5% allelic fraction in ctDNA. Comparison of IHC with FISH (n=52) identified a 63% NPA and 72% PPA. Notably, of 28 IHC 3+ tumors, 10 (36%) were negative by FISH. Tissue NGS identifies a subset of MET FISH+ tumors, however MET polysomy is largely missed by NGS assays. MET IHC 3+ staining overlaps extensively with MET FISH+ but also identifies additional potentially MET-dependent tumors. When combined with future clinical efficacy data, this technical comparison will help inform a prospective biomarker strategy for the detection of MET-driven EGFR-TKI resistance in NSCLC. Citation Format: Ryan J. Hartmaier, Ji-Youn Han, Byoung Chul Cho, Melanie M. Frigault, Aleksandra Markovets, Anne L’Hernault, David Duncan, Pierre Lao-Sirieix, J. Carl Barrett, Remy B. Verheijen, Dana Ghiorghiu, Jonathan Wessen, Geoffrey R. Oxnard. Detection of MET-mediated EGFR tyrosine kinase inhibitor (TKI) resistance in advanced non-small cell lung cancer (NSCLC): biomarker analysis of the 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 4897.

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

Abstract 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.

Abstract 1277: Honokiol, a natural product, overcomes acquired resistance of EGFR mutant NSCLC cells to the third generation EGFR inhibitor, osimertinib

Abstract Osimertinib (AZD9291) is a FDA-approved EGFR inhibitor for treating non-small cell lung cancer (NSCLC) patients with activating EGFR mutations (first-line) or those who have become resistant to 1st generation EGFR inhibitors through the T790M mutation (second-line). The development of acquired resistance to osimertinib limits the long-term benefits of patients, and effective treatment options are urgently needed. We have identified that honokiol, a natural product with potential antitumor activity, may be used to overcome osimertinib resistance. In several osimertinib-resistant cell lines including HCC827/AR, PC-9/AR, PC-9/GR/AR and PC-9/3M (with EGFR 19del, T790M and C797S mutations), the combination of honokiol and osimertinib had synergistic effects on decreasing the survival of these cell lines. The combination inhibited cell colony formation and growth, and augmented induction of apoptosis of resistant cells. This combination enhanced reduction of Mcl-1, a critical mechanism by which osimertinib induces apoptosis in sensitive EGFR mutant NSCLC cells; this effect is likely due to enhanced Mcl-1 degradation since Mcl-1 was degraded much faster in cells exposed to the combination of honokiol and osimertinib than in DMSO-treated control cells. Moreover enforced overexpression of ectopic Mcl-1 abolished the enhanced effect of honokiol and osimertinib combination on induction of apoptosis, supporting a critical role of Mcl-1 reduction in inducing apoptosis of the osimertinib-resistant cells by this combination. Our findings warrant further study of this combination for overcoming osimertinib-resistance in vivo and potentially in the clinic. (This work was supported by the NIH/NCI R01 CA223220 to SYS and Winship lung cancer pilot award to SYS). Citation Format: Hongjing ZANG, Songqing Fan, Jack Arbiser, Taofeek K. Owonikoko, Suresh S. Ramalingam, Shi-Yong Sun. Honokiol, a natural product, overcomes acquired resistance of EGFR mutant NSCLC cells to the third generation EGFR inhibitor, osimertinib [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 1277.

Third generation EGFR inhibitor osimertinib combined with pemetrexed or cisplatin exerts long-lasting anti-tumor effect in EGFR-mutated pre-clinical models of NSCLC

BackgroundThe third generation Epidermal Growth Factor Receptor (EGFR) Tyrosine Kinase Inhibitor (TKI) osimertinib has been initially approved for T790M positive Non-Small Cell Lung Cancer (NSCLC) and more recently for first-line treatment of EGFR-mutant T790M negative NSCLC patients. Similarly to previous generation TKIs, despite the high response rate, disease progression eventually occurs and current clinical research is focused on novel strategies to delay the emergence of osimertinib resistance. In this study we investigated the combination of osimertinib with pemetrexed or cisplatin in EGFR-mutated NSCLC cell lines and xenografts.MethodsTumor growth was evaluated in a PC9T790M xenograft model and tissue composition was morphometrically determined. PC9, PC9T790M and HCC827 cell lines were employed to test the efficacy of osimertinib and chemotherapy combination in vitro. Cell viability and cell death were evaluated by MTT assay and fluorescence microscopy. Protein expression and gene status were analysed by Western blotting, fluorescence in situ hybridization analysis, next-generation sequencing and digital droplet PCR.ResultsIn xenograft models, osimertinib significantly inhibited tumor growth, however, as expected, in 50% of mice drug-resistance developed. A combination of osimertinib with pemetrexed or cisplatin prevented or at least delayed the onset of resistance. Interestingly, such combinations increased the fraction of fibrotic tissue and exerted a long-lasting activity after stopping therapy. In vitro studies demonstrated the stronger efficacy of the combination over the single treatments in inhibiting cell proliferation and inducing cell death in PC9T790M cells as well as in T790M negative PC9 and HCC827 cell lines, suggesting the potential role of this strategy also as first-line treatment. Finally, we demonstrated that osimertinib resistant clones, either derived from resistant tumors or generated in vitro, were less sensitive to pemetrexed prompting to use a chemotherapy regimen non-containing pemetrexed in patients after progression to osimertinib treatment.ConclusionsOur results identify a combination between osimertinib and pemetrexed or cisplatin potentially useful in the treatment of EGFR-mutated NSCLC patients, which might delay the appearance of osimertinib resistance with long-lasting effects.

Osimertinib and dihydroartemisinin: A novel drug combination targeting head and neck squamous cell carcinoma.

e17526 Background: Recurrent and metastatic head and neck squamous cell carcinoma (HNSCC) has a dismal prognosis with limited progression-free survival and overall survival, even when treated with different combinations of chemotherapy, targeted therapies and immunotherapy. We explored in vitro and in vivo the effect of the epidermal growth factor (EGFR) inhibitor, osimertinib, alone and in combination with dihydroartemisinin (DHA) in HNSCC. Methods: The combination of osimertinib with DHA was tested in the FaDu and CAL27 HNSCC cell lines. Tumor cell proliferation assays were conducted in cultured cells and mouse xenografts. Western blotting analysis of related signal pathways was performed to investigate the molecular mechanisms of the inhibitory effect of DHA and the combination. Other compounds, which inhibit signal transducer and activator of transcription 3 (STAT3), Src-family kinases (SFKs), sphingosine kinase 1 (SPHK1), or the receptor tyrosine kinase (RTK) AXL were also combined with osimertinib in vitro. Results: Osimertinib exerted synergistic cytotoxicity toward FaDu and CAL27 HNSCC cells when combined with DHA. DHA reversed the osimertinib-induced STAT3 and Src, phosphorylation. The double combination inhibited AXL expression. The anticancer potential of osimertinib plus DHA combination was validated in vivo on FaDu and CAL27 xenografts in mice without notable side effects. Conclusions: The results illustrate that the combinatory therapy of osimertinib and DHA, as a repurposing anticancer drug, could be a novel therapeutic strategy for recurrent and/or metastatic HNSCC patients. The findings indicate that a clinical trial is warranted to confirm the benefit of the combination.

Molecular mechanisms of acquired resistance to third-generation EGFR-TKIs in EGFR T790M-mutant lung cancer.

Ann Oncol 2018; 29: i28–i37 (doi:10.1093/annonc/mdx705) In the original article, the sentence “Occurrence of grade 3 and 4 interstitial lung disease has been reported in 38% (13/34) of patients exposed to the combination of osimertinib plus durvalumab [73], …” Has been corrected to “Occurrence of interstitial lung disease has been reported in 38% (13/34) of patients exposed to the combination of osimertinib plus durvalumab, of which five were of grade 3 and 4 [73], …”. Molecular mechanisms of acquired resistance to third-generation EGFR-TKIs in EGFR T790M-mutant lung cancerAnnals of OncologyVol. 29PreviewLung cancer represents the leading cause of cancer-related deaths worldwide. Despite great advances in its management with the recent emergence of molecular targeted therapies for non-small-cell lung cancer (NSCLC), relapse of the metastatic disease always occurs within approximately one year. Epidermal growth factor receptor (EGFR) mutant tumours are the prime example of oncogene addiction and clonal evolution in oncology, regarding the emergence of resistance to first- and second-generation EGFR inhibitors. Full-Text PDF Open Archive

The role and mechanism of 2-deoxyglucose in reversing osimertinib-acquired resistance of non-small cell lung cancer cell line

Objective: To explore the role and mechanism of 2-deoxyglucose (2-dg) in reversing osimertinib- acquired resistance of non-small cell lung cancer(NSCLC)cell line. Methods: The NSCLC line H1975 (purchased from the American Type Culture Collection) was conducted by induction method in vitro to construct the osimertinib-resistance NSCLC cell line H1975-OR. The osimertinib-resistance of H1975-OR cell line was examined by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, colony-formation assay, Ki67 incorporation assay and the expression of apoptosis-related protein. The glycolysis level was assayed by the lactic acid production measured in the culture medium supernatant of H1975 and H1975-OR. The expression of glycolysis key enzymes (HK2, GLUT1, P-PKM2) and apoptosis-related protein (BIM, Bcl-2) were detected by Western blot. The cells were divided into control group, 2-deoxyglucose (4 mmol/L) monotherapy group, osimertinib (3 μmol/L) monotherapy group and 2-deoxyglucose (4 mmol/L)+ osimertinib (3 μmol/L) combination therapy group, then the apoptosis rate of cells was measured by flow cytometry to evaluate the pro-apoptotic ability of drugs. Date were analyzed by Independent-Samples t-test using SPSS 16.0 statistical software. Results: The glycolysis level of osimertinib-sensitive cell line H1975 was lower than that of osimertinib-resistance cell line H1975-OR [the yield of lactic acid, respectively, was (21.0±0.9) and (26.5±2.8) mmol·L(-1)·10(4)cells(-1), P<0.05]. The osimertinib- acquired resistance of H1975-OR could be reversed by 4 mmol/L 2-deoxyglucose(the IC(50) value of osimertinib in H1975-OR cell line decreased from (7.0±1.9) μmol/L to (1.4±0.1) μmol/L, which was close to the IC(50) value of osimertinib in H1975 cell line (1.0±0.2) μmol/L. The apoptosis rate of H1975-OR was significantly higher in 2-deoxyglucose + osimertinib combination therapy group (26.7±2.4)%, compared to control group (5.1±0.7)%, 2-deoxyglucose monotherapy group (6.1±2.5)% and osimertinib monotherapy group (11.4±2.7)%(all P<0.05). The expression of pro-apoptotic protein BIM in H1975-OR was significantly higher in 2-deoxyglucose+ osimertinib combination therapy group (177.8±28.1)% and the expression of anti-apoptotic protein Bcl-2 in H1975-OR was significantly lower in 2-deoxyglucose+ osimertinib combination therapy group (24.6±5.2)%, compared to control group (100±0)%, all P<0.05. Conclusion: 2-deoxyglucose can reverse the acquired resistance of NSCLC cell line to osimertinib, which may be related to the inhibition of cell glycolysis and the induction of apoptosis.

Activation of AXL as a Preclinical Acquired Resistance Mechanism Against Osimertinib Treatment in EGFR-Mutant Non-Small Cell Lung Cancer Cells.

Osimertinib (AZD9291) has an efficacy superior to that of standard EGFR-tyrosine kinase inhibitors for the first-line treatment of patients with EGFR-mutant advanced non-small cell lung cancer (NSCLC). However, patients treated with osimertinib eventually acquire drug resistance, and novel therapeutic strategies to overcome acquired resistance are needed. In clinical or preclinical models, several mechanisms of acquired resistance to osimertinib have been elucidated. However, the acquired resistance mechanisms when osimertinib is initially used for EGFR-mutant NSCLC remain unclear. In this study, we experimentally established acquired osimertinib-resistant cell lines from EGFR-mutant NSCLC cell lines and investigated the molecular profiles of resistant cells to uncover the mechanisms of acquired resistance. Various resistance mechanisms were identified, including the acquisition of MET amplification, EMT induction, and the upregulation of AXL. Using targeted next-generation sequencing with a multigene panel, no secondary mutations were detected in our resistant cell lines. Among three MET-amplified cell lines, one cell line was sensitive to a combination of osimertinib and crizotinib. Acquired resistance cell lines derived from H1975 harboring the T790M mutation showed AXL upregulation, and the cell growth of these cell lines was suppressed by a combination of osimertinib and cabozantinib, an inhibitor of multiple tyrosine kinases including AXL, both in vitro and in vivo. Our results suggest that AXL might be a therapeutic target for overcoming acquired resistance to osimertinib. IMPLICATIONS: Upregulation of AXL is one of the mechanisms of acquired resistance to osimertinib, and combination of osimertinib and cabozantinib might be a key treatment for overcoming osimertinib resistance.