High-Trough Plasma Concentration of Afatinib Is Associated with Dose Reduction

Afatinib 30 mg in the treatment of common and uncommon EGFR-mutated advanced lung adenocarcinomas: a retrospective, single-center, longitudinal study

Background

Afatinib 30 mg has been proved to be with comparable efficacy but more tolerable than the dose of 40 mg for Asian patients with non-small cell lung cancer (NSCLC). This study aimed to investigate the clinical outcomes of afatinib at 30 mg/d in the treatment of advanced lung adenocarcinomas (LAD) with common and uncommon epidermal growth factor receptor (EGFR) mutations.

Methods

EGFR-mutated advanced LAD patients receiving afatinib (30 mg/d) from January 2017 to November 2021 were retrospectively included. EGFR status was classified into three subtypes, namely common mutations including exon 19 deletions (19del) and exon 21 L858R (21L858R), uncommon mutations including G719X, L861Q, S768I, and complex mutations, and separately exon 20 insertions (20ins). Progression-free survival (PFS), objective response rate (ORR), disease control rate (DCR) and adverse events (AEs) were analyzed during regular follow-up.

Results

The overall median PFS of totally 58 included patients was 9.83 [95% confidence index (CI): 5.76–13.91] months. The number of patients with common, uncommon, and 20ins mutations was 32 (55.2%), 19 (32.8%) and 7 (12.1%), respectively. Baseline characteristics did not differ significantly among the three subtypes. The corresponding median PFS was 13.97 (12.06–15.89), 8.48 (0.32–16.64), and 3.78 (1.93–5.64) months, respectively (P=0.002). In the first-line setting, patients with common and uncommon mutations had a significantly longer PFS compared to those with 20ins [14.53 (13.53–15.53) vs. 10.39 (4.87–15.91) vs. 2.37 (0.00–5.11) months, P<0.001]. The first-line ORR showed significant differences among the three subtypes (60% vs. 80% vs. 0.0%, P=0.023). All-grade AEs occurred in 22 patients (37.9%). AEs ≥ grade 3 mainly included diarrhea (8.6%), and none of the patients discontinued treatment due to severe AEs.

Conclusions

Afatinib at 30 mg/d is associated with a favorable efficacy and tolerability in the treatment of advanced LAD with common and major uncommon EGFR mutations except 20ins. Further large-scale prospective studies are warranted to confirm our findings.

Discrimination of hand-foot skin reaction caused by tyrosine kinase inhibitors based on direct keratinocyte toxicity and vascular endothelial growth factor receptor-2 inhibition

Tyrosine kinase inhibitors (TKIs) are molecular-targeted anticancer drugs. Their benefits are limited by dermal toxicities, including hand-foot skin reaction (HFSR), which is commonly found in skin areas subjected to friction. The present study aimed to explain the incidence of HFSR in patients treated with TKIs by focusing on keratinocyte toxicity and inhibition of vascular endothelial growth factor receptor (VEGFR), which plays an essential role in angiogenesis. Mice with gene knockout for the immunosuppressive cytokine interleukin-10 exhibited HFSR-like phenotypes, such as cytotoxicity in keratinocytes and increased number and size of blood vessels after repeated doses of regorafenib, sorafenib, and pazopanib, all of which cause high incidence of HFSR, in combination with tape-stripping mimicking skin damage at the friction site. Comprehensive examination of the direct cytotoxic effects of 21 TKIs on primary cultured human keratinocytes revealed that 18 of them reduced the cell viability dose-dependently. Importantly, the ratio of the trough concentration in patients (C_trough) to the LC₅₀ values of cell viability reduction was higher than unity for four HFSR-inducing TKIs, suggesting that these TKIs cause keratinocyte toxicity at clinically relevant concentrations. In addition, eight HFSR-inducing TKIs caused inhibition of VEGFR-2 kinase activity, which was validated by their ratios of C_trough to the obtained IC_50,VEGFR-2 of more than unity. All 12 TKIs with no reported incidence of HFSR exhibited less than unity values for both C_trough/LC_{50,keratinocytes} and C_trough/IC_50,VEGFR-2. These results suggested that a combination of keratinocyte toxicity and VEGFR-2 inhibition may explain the incidence of HFSR upon TKI usage in humans.