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Lower gefitinib dose led to earlier resistance acquisition before emergence of T790M mutation in epidermal growth factor receptor-mutated lung cancer model.

ABSTRACT: Non-small-cell lung cancers with epidermal growth factor receptor (EGFR) mutations are sensitive to EGFR tyrosine kinase inhibitors (TKIs); however, unlike cytotoxic agents, it is generally accepted that minimal doses of drugs inhibiting target molecules are sufficient when molecular-targeted agents, including EGFR-TKIs, are used. Thus, any utility of higher doses remains unclear. We compared low-dose (15 mg/kg) gefitinib therapy with high-dose (50 mg/kg) therapy using an EGFR-mutated lung cancer xenograft model. Both gefitinib doses induced tumor shrinkage, but tumors regrew in the low-dose group within 1 month, whereas tumors in the high-dose group did not. Neither the T790M mutation nor MET amplification was apparent in regrown tumors. We also compared outcomes after two doses of gefitinib (5 and 25 mg/kg) in a transgenic EGFR-mutated lung cancer mouse model. In line with the results obtained using the xenograft model, both gefitinib doses completely inhibited tumor growth, but tumors treated with the lower dose of gefitinib developed earlier drug resistance. In conclusion, a low gefitinib dose caused tumors to become drug-resistant prior to acquisition of the T790M mutation or MET amplification in EGFR-mutated models of lung cancer. This suggests that it is important to optimize the EGFR-TKI dose for treatment of EGFR mutation-associated lung cancer. Gefitinib may need to be given at a dose greater than the minimum required for inhibition of target molecules.

SUBMITTER: Hayakawa H

PROVIDER: S-EPMC7654246 | biostudies-literature | 2013 Nov

REPOSITORIES: biostudies-literature

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Lower gefitinib dose led to earlier resistance acquisition before emergence of T790M mutation in epidermal growth factor receptor-mutated lung cancer model.

Hayakawa Hiromi H Ichihara Eiki E Ohashi Kadoaki K Ninomiya Takashi T Yasugi Masayuki M Takata Saburo S Sakai Katsuya K Matsumoto Kunio K Takigawa Nagio N Tanimoto Mitsune M Kiura Katsuyuki K

Cancer science 20131025 11

Non-small-cell lung cancers with epidermal growth factor receptor (EGFR) mutations are sensitive to EGFR tyrosine kinase inhibitors (TKIs); however, unlike cytotoxic agents, it is generally accepted that minimal doses of drugs inhibiting target molecules are sufficient when molecular-targeted agents, including EGFR-TKIs, are used. Thus, any utility of higher doses remains unclear. We compared low-dose (15 mg/kg) gefitinib therapy with high-dose (50 mg/kg) therapy using an EGFR-mutated lung cance ...[more]

PMID: 24033722

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Project description:BackgroundLeptomeningeal metastasis (LM) is a catastrophic complication for patients with non-small cell lung cancer (NSCLC) and carries an extremely poor prognosis. The efficacy of osimertinib 80 mg once daily for epidermal growth factor receptor-mutated (EGFRm) NSCLC with LM has yet to be fully assessed. This study aimed to investigate the efficacy of osimertinib in such patients and their genetic profiles at the time of LM diagnosis.MethodsFrom January 2016 to April 2020, pretreated EGFRm NSCLC patients who had progressed with cytologically confirmed symptomatic LM and received osimertinib 80 mg once daily were enrolled retrospectively. The objective response rate (ORR) and disease control rate (DCR) were evaluated, along with progression-free survival (PFS) and overall survival (OS). Next-generation sequencing of paired samples of cerebrospinal fluid and plasma collected at LM diagnosis was performed simultaneously.ResultsForty cases of EGFRm lung adenocarcinoma with LM were analyzed. Females accounted for 75.0% of enrollees. Of the patients, 37.5% had a poor Eastern Cooperative Oncology Group score (≥2). Twelve patients had received at least 2 prior lines of treatment. All patients received osimertinib treatment regardless of their T790M status. According to the Response Assessment in Neuro-Oncology (RANO)-LM criteria, the ORR and DCR were 20.0% and 95.0%, respectively. The median PFS and OS were 10.0 (95% CI: 7.7-12.3) and 15.1 months (95% CI: 11.0-19.4), respectively. No significant difference was observed between T790M-negative patients (n=24) and T790M-positive patients (n=16) with respect to PFS [median, 10.8 (95% CI: 7.7-13.8) vs. 8.8 months (95% CI: 7.3-10.3), HR=0.595, P=0.158] or OS [median, 17.2 (95% CI: 8.7-25.7) vs. 11.4 months (95% CI: 3.9-19.0), HR=0.913, P=0.822]. The detection rate of EGFR sensitizing mutations in cerebrospinal fluid was higher than that in plasma (97.5% vs. 50%, P=0.311), whereas the incidence of T790M detection in cerebrospinal fluid was significantly lower than that in plasma (20.0% vs. 32.5%, P=0.043).ConclusionsOsimertinib 80 mg once daily shows good efficacy in pretreated EGFRm NSCLC patients with LM regardless of their T790M status. Combining cerebrospinal fluid and plasma testing can aid in revealing more genetic information.

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Lower gefitinib dose led to earlier resistance acquisition before emergence of T790M mutation in epidermal growth factor receptor-mutated lung cancer model.

Publications

Lower gefitinib dose led to earlier resistance acquisition before emergence of T790M mutation in epidermal growth factor receptor-mutated lung cancer model.

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