Inconsistent clinical outcomes following afatinib treatment in NSCLC patients harboring uncommon epidermal growth factor receptor mutation

Specifying the choice of EGFR-TKI based on brain metastatic status for advanced NSCLC with EGFR p.L861Q mutation

BACKGROUND

In-depth insight into the genomic features of the uncommon EGFR p.L861Q mutant NSCLC is scarcely performed, and no consensus on the preferred treatment strategy has been established. Moreover, the therapeutic implications of EGFR-TKI stratified by clinical and molecular features remained largely unknown.

METHODS

A multi-center NGS database comprising 44,993 NSCLC samples was utilized for the genomic landscape profiling of EGFR p.L861Q mutation. Furthermore, a real-world cohort of 207 patients harboring EGFR p.L861Q mutation with complete treatment history was curated for comprehensive clinical analysis.

RESULTS

L861Q is prevalent in approximately 2.1% of EGFR-mutated NSCLC and is typically co-mutated with EGFR p.G719X on the same allele (20%) and exhibits co-occurrent EGFR copy number amplification in approximately 17% of cases. In the first-line setting, afatinib and third-generation EGFR-TKI have been shown to yield notably superior treatment outcomes compared to first-generation EGFR-TKI (1st vs.2nd vs.3rd generations, ORR: 15.8% vs.56.5% vs.46.7%, P=0.01; median PFS: 6.4 vs.13.5 vs.15.1 months, P=0.002). This finding consistently held for patients without CNS metastases (1st vs.2nd vs.3rd generations, median PFS:6.0 vs.18.2 vs.14.1 months, P=0.003). In contrast, third-generation EGFR-TKI demonstrated superior efficacy compared to afatinib or first-generation TKI among the subgroup of brain metastasis (Pooled 1st/2nd-generation vs.3rd-generation TKI, brain ORR:0.00% vs.33.33%; median PFS:7.9 vs.19.3 months, P=0.021). Additional concurrent EGFR mutations or EGFR amplification did not yield a discernible impact on the efficacy of EGFR-TKI.

CONCLUSIONS

The present study comprehensively elucidates the molecular features of EGFR p.L861Q mutation and underscores the optimal therapeutic choice of first-line EGFR-TKI based on brain metastatic status.

Efficacy of targeted therapy in patients with non-small cell lung cancer harboring very rare mutations in EGFR exon 18

Background

Somatic mutations in epidermal growth factor receptor (EGFR) exon 18 are classified as uncommon or rare mutations in non-small cell lung cancer (NSCLC), in this context, other than G719X or E709X exon 18 mutations are even more rare and heterogeneous. In such scenario, first line treatment options are still debated. The aim of this study was to investigate the response of NSCLC patients harboring very rare exon 18 mutations to EGFR tyrosine kinase inhibitors (EGFR-TKIs).

Methods

This retrospective descriptive study included 105 patients with NSCLC harboring mutations in EGFR exon 18 diagnosed at West China Hospital. The clinical response to EGFR-TKIs was evaluated according to different classifications of mutations in 45 NSCLC patients: 39 harboring G719X or E709X mutations and 6 harboring very rare mutations in EGFR exon 18.

Results

Among 105 patients, 84% (88/105) harbored rare mutations in EGFR exon 18, including G719X and E709X mutations. The remaining 16% (17/105) had very rare mutations in EGFR exon 18, including E709_710delinsX and G724S. For the subsequent efficacy analysis of EGFR-TKI in 45 NSCLC patients, patients harboring very rare mutations achieved a favorable disease control rate (DCR) of 100% and had a median progression-free survival (PFS) of 17.2 months, which was not significantly different compared to patients harboring G719X or E709X (P=0.59).

Conclusions

EGFR-TKIs showed great efficacy in terms of responses and survival in patients harboring exon 18 EGFR rare mutations. This may justify the use of targeted therapies as a potential treatment strategy for these patients.

Afatinib overcoming resistance to icotinib and osimertinib in NSCLC with leptomeningeal metastasis in patients with acquired EGFR L858R/T790M or L858R/S768I mutations: Two case reports

Background

Advanced non-small cell lung cancer (NSCLC) is often complicated by leptomeningeal metastases (LMs), especially in patients carrying EGFR mutations. EGFR tyrosine kinase inhibitors (TKIs) are the first-line drug for patients with specific gene mutations, such as EGFR exon 19 deletion or exon 21 L858R mutation. However, after long-term TKI use, patients eventually develop drug resistance and acquire new mutations. Acquiring the EGFR T790 M mutation during TKI treatment is a marker for first/second generation TKI resistance. Osimertinib (a third-generation TKI) could overcome this resistance, especially for patients who have already developed NSCLC-LM. Treating NSCLC patients with osimertinib resistance is challenging. Our aim was to investigate whether afatinib is effective in NSCLC-LM patient who showed resistance to osimertinib. Herein, we report two patients with resistance to first- and third-generation TKIs who benefited from second-generation TKI.

Case summary

Case one: A 43-year-old man was diagnosed with stage 3A NSCLC with EGFR exon 19 deletion. He underwent surgery and received 4 rounds of chemotherapy (oxaliplatin combined with liposomal paclitaxel), after which the disease was controlled by icotinib (a first-generation TKI) for 4 years. Then, he showed poor drug response and bone metastasis. A liquid biopsy was carried out, and the EGFR L858R/T790 M compound mutation was found. The patient was given osimertinib (a third-generation TKI). The patient was in a stable condition for 2 years and then he developed bilateral peripheral facial palsy. Brain MRI showed enhancement in the left temporal lobe and meninges, and cerebrospinal fluid (CSF) cytology detected tumour cells in the CSF. NSCLC-LM was diagnosed. His performance status (PS) score was 3-4. Liquid biopsy and next-generation sequencing were performed again. Different gene mutations and copy number alterations were found this time, including EGFR L858R, but without the EGFR T790 M mutation. His disease was controlled with intrathecal methotrexate and oral afatinib (a second generation TKI). The patient has shown clinical remission (PS score: 1-2) until now, which is longer than 10 months.

Case two

A 50-year-old man was diagnosed with NSCLC in May 2020. He underwent one round of chemotherapy before thoracoscopic partial lobectomy of the right upper lung. Histological study of the lung tissue showed lung adenocarcinoma with the EGFR L858R mutation. Then, the disease was controlled with icotinib. One year later, he was diagnosed with NSCLC-LM. Liquid biopsy and sequencing showed an EGFR L858R/S768I compound mutation. The patient was treated with osimertinib. His condition was stable for 5 months before his central nervous system (CNS) symptoms were exacerbated. Liquid biopsy and sequencing were carried out again, and his gene mutation profile had not changed much. Then, the patient was given afatinib, and his condition has remained stable for 11 months.

Conclusion

Afatinib might be suitable for NSCLC-LM patients with EGFR compound mutations who show resistance to icotinib and osimertinib, since it might help overcome first- and third-generation TKI resistance.