P2.03-025 Prevalence of EGFR T790M Mutation in NSCLC Patients after Afatinib Failure, and Subsequent Response to Osimertinib

Outcomes of Patients with EGFR-Mutant Advanced NSCLC in a Developing Country in Southeast Asia

Background

Although first- and second-generation EGFR TKIs are considered first-line treatment in EGFRm+ NSCLC, most patients develop resistance and progress, commonly, EGFR T790M mutation. The third-generation EGFR-TKI has demonstrated efficacy in patients with progressive disease harboring the T790M mutation and in the first-line setting, bypassing this mode of resistance. The primary objectives of this study are to describe the proportion of EGFRm+ NSCLC patients treated with first-, second- and third-generation EGFR TKIs, and cytotoxic chemotherapy in the first-line setting, and the time on treatment for each category. Secondary objectives are to determine the dropout rate, the rates for T790M mutation testing at disease progression and the type of subsequent treatment.

Methods

This multicenter retrospective study utilized data from the Malaysian Lung Cancer Registry that actively registers all lung cancer patients ≥18 years, with primary lung cancer confirmed histologically or cytologically. All patients diagnosed with advanced stages (ie stages IIIB, IIIC and IV) EGFRm+ NSCLC from 1st of January 2015 to 31st December 2019 were included.

Results

Of 406 patients with EGFRm+ NCSLC, 351 were treated. Types of first-line treatment were as follows: EGFR-TKIs (first generation - 54.1%, second generation - 25.6% and third-generation - 12.5%) and chemotherapy (7.7%). The median time of treatment for each generation of EGFR-TKI was 12 months, 12 months and 24 months, and 2 months for chemotherapy. The dropout rate was 28.7% (n = 101). Nearly half (49.4%) of patients who were on first- or second-generation EGFR-TKI had further genetic testing via liquid or tissue biopsies upon disease progression. About 24.9% of those who developed disease progression after first- or second-generation EGFR TKI were started on a third-generation EGFR TKI.

Conclusion

In the real-world, the management of EGFRm+ advanced NSCLC patients in an Asian cost-restrictive setting may adversely affect the choice of first-line therapy, time on each line of treatment and subsequently the overall survival of patients.

Osimertinib versus afatinib in patients with T790M-positive, non-small-cell lung cancer and multiple central nervous system metastases after failure of initial EGFR-TKI treatment

Background

The purpose of this study was to compare the efficacy of osimertinib (OSI) versus afatinib (AFA) in patients with T790M-positive, non-small-cell lung cancer (NSCLC) and multiple central nervous system (CNS) metastases after failure of initial epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) treatment.

Methods

Consecutive patients with T790M-positive NSCLC and multiple CNS metastases after failure of initial EGFR-TKI treatment were retrospectively identified from our medical institution during 2016–2018 and underwent either oral 80 daily OSI or oral 40 daily AFA every 3 weeks for up to 6 cycles, until disease progression, intolerable adverse events (AEs), or death. The co-primary endpoints were overall survival (OS) and progression-free survival (PFS).

Results

The cohort consisted of 124 patients (OSI: n = 60, mean age = 64.24 years [SD: 12.33]; AFA: n = 64, mean age = 64.13 years [SD: 13.72]). After a median follow-up of 24 months (range, 3 to 28), a significant improvement in OS was detected (hazard ratio [HR] 0.59, 95% confidence interval [CI], 0.39–0.91; p = 0.0160; median, 13.7 months [95% CI, 11.1–14.8] for OSI vs 9.6 months [95% CI, 8.4–10.2] for AFA). The median duration of PFS was significantly longer with OSI than with AFA (HR 0.62; 95% CI, 0.41–0.91; p = 0.014; median, 4.5 months [95% CI, 3.5–5.7] vs 3.9 months [95% CI, 3.1–4.8]). The proportion of grade 3 or higher adverse events (AEs) was lower with OSI (22.4%) than with AFA (39.4%).

Conclusions

In patients with T790M-positive NSCLC and multiple CNS metastases after failure of initial EGFR-TKI treatment, OSI may be associated with significantly improved survival benefit compared with AFA, with a controllable tolerability profile.

Therapies after first-line afatinib in patients with EGFRm+ NSCLC in Japan: retrospective analysis of LUX-Lung 3

Aim: Acquired resistance to EGFR tyrosine kinase inhibitors is inevitable in non-small-cell lung cancer. To inform subsequent treatment decisions, we retrospectively assessed therapies following afatinib in Japanese patients from LUX-Lung 3. Patients & methods: LUX-Lung 3 was a randomized, open-label, Phase III study of afatinib versus cisplatin/pemetrexed in treatment-naive patients with EGFR mutation-positive ( EGFRm+) advanced lung adenocarcinoma. Results: Among 47 Japanese patients who discontinued first-line afatinib, 91/81/62% received ≥one/two/three subsequent therapies. The most common second-line therapies were platinum-based chemotherapy (38%) and a first-generation EGFR tyrosine kinase inhibitor (17%). Median overall survival (afatinib vs cisplatin/pemetrexed) was 47.8 versus 35.0 months (not significant). Conclusion: First-line afatinib does not appear to diminish suitability for subsequent therapies in EGFRm+ non-small-cell lung cancer.

Tumor clonality and resistance mechanisms in EGFR mutation-positive non-small-cell lung cancer: implications for therapeutic sequencing

While the development of EGFR-targeted tyrosine kinase inhibitors (TKIs) has revolutionized treatment of EGFR mutation-positive non-small-cell lung cancer, acquired resistance to therapy is inevitable, reflecting tumor evolution. Recent studies show that EGFR mutation-positive non-small-cell lung cancer is highly heterogeneous at the cellular level, facilitating clonal expansion of resistant tumors via multiple molecular mechanisms. Here, we review the mechanistic differences between first-, second- and third-generation EGFR-targeted TKIs and speculate how these features could explain differences in clinical activity between these agents from a clonal evolution perspective. We hypothesize that the molecular dissection of tumor resistance mechanisms will facilitate optimal sequential use of EGFR TKIs in individual patients, thus maximizing the duration of chemotherapy-free treatment and survival benefit.

Sequential treatment with afatinib and osimertinib in patients with EGFR mutation-positive non-small-cell lung cancer: an observational study

Aim: To assess outcomes in patients with EGFR mutation-positive (Del19, L858R) non-small-cell lung cancer receiving sequential afatinib and osimertinib in a real-world clinical setting. Materials & methods: In this retrospective, observational, multicenter study, patients (n = 204) had T790M-positive disease following first-line afatinib and started osimertinib treatment ≥10 months prior to data entry. Primary outcome was time on treatment. Results: Overall median time on treatment was 27.6 months (90% CI: 25.9–31.3), 30.3 months (90% CI: 27.6–44.5) in Del19-positive patients and 46.7 months (90% CI: 26.8–not reached) in Asians. The 2-year overall survival was 78.9%. Conclusion: In real-world clinical practice, sequential afatinib and osimertinib facilitates prolonged, chemotherapy-free treatment in patients with T790M acquired resistance, and is a potentially attractive strategy, especially for Del19-positive tumors.

Trial registration number: NCT03370770

Afatinib in advanced NSCLC: a profile of its use

Afatinib [Giotrif^® (EU); Gilotrif^® (USA)] is an orally administered, irreversible inhibitor of the ErbB family of tyrosine kinases that provides an important first-line treatment option for advanced non-small cell lung cancer (NSCLC) with activating epidermal growth factor receptor (EGFR) mutations (i.e. EGFR^actMUT+), and an additional treatment option for squamous NSCLC that has progressed following first-line platinum-based chemotherapy. Relative to gefitinib in the first-line treatment of EGFR^actMUT+ advanced lung adenocarcinoma, afatinib prolonged progression-free survival (PFS) and time to treatment failure (TTF), but not overall survival (OS). Afatinib also prolonged PFS, but not OS, versus cisplatin-based chemotherapy in this setting; however, afatinib improved OS versus chemotherapy in the subgroup of patients with deletions in exon 19. As a second-line treatment for advanced squamous NSCLC, afatinib prolonged PFS and OS compared with erlotinib, regardless of EGFR mutation status. Afatinib had a predictable and manageable tolerability profile.