EGFR C797S

After receiving dacomitinib and almonertinib sequentially, plasma-based NGS revealed the emergence of EGFR T790M-trans-C797S mutations, prompting a switch to a combination therapy of almonertinib and gefitinib...Larotrectinib was incorporated into the dual EGFR-TKI regimen, forming a triplet therapy...This is the first reported case of a novel, targetable POT1::NTRK3 fusion as a potential off-target mechanism mediating EGFR-TKI resistance, occurring alongside MET amplification in a patient with NSCLC harboring acquired EGFR L858R/T790M/C797S mutations. Concomitant inhibition of EGFR, NTRK, and MET was safe and resulted in a significant response, underscoring the importance of precision medicine guided by matched NGS.

While first, second, and third-generation EGFR-TKIs have made significant progress in overcoming EGFR kinase resistance, the emergence of the EGFR-C797S mutation poses a substantial challenge, particularly in the context of resistance to Osimertinib...Preclinical and early-phase clinical trials of these inhibitors are promising, though further optimization of pharmacokinetic and safety profiles is crucial for future clinical success. This work offers key insights for medicinal chemists in the design and development of fourth-generation EGFR inhibitors to address drug-resistant mutations in NSCLC.

The study suggests that hybrid scaffolds combining key pharmacophoric features from Osimertinib and Brigatinib along with Lys745 targeting warheads, could enhance selectivity and potency. Fourth-generation TKIs targeting Lys745 offer a novel therapeutic avenue, potentially overcoming mutation-induced resistance and improving NSCLC treatment outcomes. This approach represents a critical advancement toward durable clinical responses in patients with drug-resistant cancer.

Compound 31 inhibited EGFR L858R/T790M/C797S in biochemical assays with a Ki = 2.1 nM and EGFR del19/T790M/C797S in a Ba/F3 cellular assay with an IC50 = 56.9 nM. The deuterated analogue of 31 (38) demonstrated dose-dependent tumor growth inhibition in a Ba/F3 EGFR del19/T790M/C797S CDX model by 47% at 50 mg/kg BID and 92% at 100 mg/kg BID.

Third-generation TKIs, such as osimertinib, almonertinib and furmonertinib, are effective for the treatment of NSCLC that is EGFR-sensitizing mutation-positive and T790M-positive. To the best of our knowledge, the present report describes the first case of a patient with lung adenocarcinoma who had multiple co-existing EGFR resistance mutations, including EGFR L718Q, EGFR C797S, EGFR C797G, EGFR L792H, EGFR V802F and EGFR V689L. These mutations conferred resistance to almonertinib, whilst maintaining sensitivity to afatinib.

The strong inhibitory activity against EGFR was attributed to two key residues, M793 and S797, via hydrogen bonding, corresponding with lower solvent accessibility and a higher number of atomic contacts. Therefore, these potent compounds could be developed as promising drugs targeting both wild-type and mutant EGFR for the treatment of NSCLC.

In contrast, related Type I1/2 inhibitors target wild-type EGFR but are less effective against resistant mutants. This shift in selectivity demonstrates that mutant-selective AABIs classify as "Type V" bivalent inhibitors.

The known resistance mechanisms, including MET amplification, EGFR (C797S, L718Q/R), TP53, CDK4, CDK6, CDKN2A, BRAF, KRAS, NRAS and PIK3CA mutations were also disclosed in our cohort. NGS assay can achieve a high concordance with FISH in MET amplification detection and has advantages in portraying various genetic alterations, which is of worthy in clinical promotion.

These effects are associated with binding of 1,4,5,6-tetrahydroxy-7,8-diprenylxanthone to EGFR resulting in the suppression of extracellular signal-regulated kinase (Erk) phosphorylation. In conclusion, our results suggest that 1,4,5,6-tetrahydroxy-7,8-diprenylxanthone may be a potential novel candidate for further investigation and treatment of NSCLC with the triple-mutant EGFR.

Interestingly, strong hydrophobic interactions were also observed with the C-terminal tail residues, such as PHE997 and ALA1000 as well as with ARG999 for the YSIPKSS peptide and most of the conjugates...Overall, our results show that the (7-DGA)2-K, di-conjugate, the (7-DGA)2-Y di-conjugate, and the neat YSIPKSS demonstrated strong and stable binding with the L858R mutant and the highly resistant triple mutant EGFR, respectively. The novel designed conjugates demonstrate potential for further optimization for laboratory studies aimed at developing new therapeutics for targeting specific EGFR mutant expressing cells.

Selected population could obtain clinical benefit from afatinib plus bevacizumab, based on rebiopsy results after osimertinib resistance.

Nevertheless, disease progression inevitably occurs, limiting osimertinib long-term efficacy...Early phase 1/2 clinical trials are ongoing to elucidate their activity also in the clinical setting. Aim of this review is to provide a state-of-the-art analysis on preclinical development of fourth-generation EGFR-TKIs and promising preliminary clinical data.