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    Preclinical assessment of combination therapy of EGFR tyrosine kinase inhibitors in a highly heterogeneous tumor model
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    Abstract:
    Abstract The development of tyrosine kinase inhibitors (TKIs) has improved the treatment of non-small cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR) mutations. The current research priority is to provide viable treatments for patients who have drug-resistant EGFR mutations. We evaluated the drug sensitivity of various EGFR mutants to monotherapies and combination therapies of EGFR-TKIs. In vitro, the transforming potential and drug sensitivity of 357 EGFR variants were assessed. In vivo, we tested the sensitivity of EGFR variants to different regimens of EGFR-TKIs by examining changes in the proportion of each variant within the tumor. Out of 357 variants thoroughly examined for transforming activities, 144 (40.3%) and 282 (79.0%) transformed 3T3 and Ba/F3 cells, respectively. Among the latter variants, 50 (17.7%) were found to be resistant or only partly resistant to osimertinib or afatinib. Four of 25 afatinib-resistant variants (16%) were sensitive to osimertinib, whereas 25 of 46 osimertinib-resistant variants (54.3%) were sensitive to afatinib. Despite the lack of a synergistic impact, TKI combination treatment effectively reduced in vivo the heterogeneous tumors composed of 3T3 cells with different EGFR variants. Regimens starting with afatinib and subsequently switched to osimertinib suppressed tumor development more efficiently than the opposite combination. Combination EGFR-TKI treatment may decrease tumor growth and prevent the development of resistant variants. This work created an experimental model of a heterogeneous tumor to find the best combination therapy regimen and proposes a basic notion of EGFR-TKI combination therapy to enhance the prognosis of NSCLC patients.
    Keywords:
    Afatinib
    Osimertinib
    Combination therapy
    Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have revolutionized the treatment of advanced non-small cell lung cancer (NSCLC) and contributed to the development of precision medicine. Osimertinib is a standard first-line (1L) treatment for EGFR-mutated NSCLC and has demonstrated superior survival benefits over previous-generation TKIs. However, resistance to osimertinib is nearly inevitable, and subsequent treatment strategies remain unmet medical needs in this setting. Afatinib, a second-generation EGFR-TKI, exhibits activity against certain uncommon EGFR mutation types in the 1L setting. There are a few case reports on the efficacy of afatinib against EGFR-dependent resistance after osimertinib treatment, although these have not been prospectively investigated.The present phase II, single-arm multicenter trial aims to verify the efficacy and safety of afatinib rechallenge after 1L osimertinib resistance. Patients (aged ≥20 years) with advanced or recurrent non-squamous NSCLC harboring drug-sensitive EGFR mutations (deletion of exon 19 or L858R) who were previously treated with 1L osimertinib and second-line chemotherapy other than TKIs are considered eligible. Undergoing next-generation sequence-based comprehensive genomic profiling is one of the key inclusion criteria. The primary endpoint is the objective response rate; the secondary endpoints are progression-free survival, overall survival, and tolerability. Thirty patients will be recruited in December 2023.The results of this study may promote incorporating afatinib rechallenge into the treatment sequence after 1L osimertinib resistance, a setting in which concrete evidence has not been yet established.UMIN Clinical Trial Registry: UMIN000049225.
    Afatinib
    Osimertinib
    Citations (6)
    Background/Aim: Treatment with EGFR-tyrosine kinase inhibitor (TKI) shows a durable response against NSCLC harboring EGFR mutation; however, treatment resistance occurs within 1-1.5 years following first-line EGFR-TKIs [first- and second-generation (G) TKIs]. When resistant NSCLC exhibits T790M mutations, osimertinib is the standard therapy. However, intratumoral heterogeneity and clonal evolution may occur in NSCLC. Afatinib may overcome tumor heterogeneity, leading to T790M colonal purity. We aimed to determine whether NSCLC treatment with afatinib followed by osimertinib (afatinib group) provides higher therapeutic efficacy than other 1st-G EFGR-TKIs followed by osimertinib (1st-G group). Materials and Methods: This multicenter retrospective study evaluated outcomes between afatinib group and 1st-G group. We analyzed clinical data from NSCLC patients receiving osimertinib after progression following 1st- or 2nd-G EGFR-TKIs between March 28, 2016 and March 31, 2018. Patients with performance status (PS) 0-2 were enrolled to reduce bias of patients9 conditions. Results: We enrolled 111 patients treated with osimertinib. The median age was 69 (range: 39-88) years. Out of 111 patients, 33 (29.7%) were men, 100 (90%) had PS 0-1, and 35 (31.5%) were in the afatinib group. The objective RR and DCR were significantly higher in the afatinib group than in the 1st-G group [82.9% vs. 53.9% (p=0.0065); 91.4% vs. 71.1% (p=0.032)]. The median PFS tended higher in the afatinib group than in the 1st-G group (15.6 vs. 8.9 months, p=0.195). Conclusion: Afatinib followed by osimertinib may provide better outcomes for T790M-positive NSCLC than 1st-G EGFR-TKIs. Afatinib followed by osimertinib may be a therapeutic option for NSCLC harboring EGFR mutation.
    Afatinib
    Osimertinib
    T790M
    Citations (28)
    Aims: Overall survival (OS) and updated time to treatment failure (TTF) analysis of patients with EGFR mutation-positive (Del19, L858R) non-small-cell lung cancer who received sequential afatinib/osimertinib in the real-world GioTag study. Patients & methods: Patients had T790M-positive disease following first-line afatinib and received osimertinib treatment (n = 203). Primary outcome was TTF. The OS analysis was exploratory. Results: Median OS was 41.3 months (90% CI: 36.8–46.3) overall and 45.7 months (90% CI: 45.3–51.5) in patients with Del19-positive tumors (n = 149); 2-year survival was 80 and 82%, respectively. Updated median TTF with afatinib and osimertinib was 28.1 months (90% CI: 26.8–30.3). Conclusion: Sequential afatinib/osimertinib was associated with encouraging OS/TTF in patients with EGFR T790M-positive non-small-cell lung cancer, especially in patients with Del19-positive tumors. Trial registration number: NCT03370770
    Afatinib
    Osimertinib
    Citations (76)