EGFR C797S

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.

This multicenter registration study investigated tissue-based NGS for a specific patient population with NSCLC in Taiwan.

For example, patients on gefitinib, a first-generation TKI, experienced a progression-free survival (PFS) of 10 months compared to 5 months with conventional chemotherapy. Second-generation TKI afatinib outperformed erlotinib and extended PFS to 11.1 months compared to 6.9 months with cisplatin...Several trials have started showing promising in vitro and in vivo results, but more trials are needed before clinical approval. This review underscores notable advancements in the field of EGFR TKIs, offering a comprehensive analysis of their mechanisms of action and the progression of various TKI generations in response to resistance.

In example applications, TransTACs enabled the reversible control of human primary chimeric antigen receptor T cells and the targeting of drug-resistant epidermal growth factor receptor-driven lung cancer with the exon 19 deletion/T790M/C797S mutations in a mouse xenograft model. TransTACs represent a promising new family of bifunctional antibodies for precise manipulation of membrane proteins and targeted cancer therapy.

NGS using either tissue or liquid biopsy samples from advanced T790M-mutated NSCLC patients with acquired resistance to osimertinib therapy can detect various genomic alternations. Future studies focusing on subsequent tailored therapies on the basis of NGS results are warranted.

A series of derivatives of Erlotinib and Icotinib were developed by incorporating a macrocyclic polyamine into a quinazoline scaffold to enhance their inhibitory activity against drug-resistant cells. Compound b demonstrated slightly improved inhibition activity against PC-9 Del19/T790M/C797S (IC50 = 496.3 nM). This could provide some insights for optimizing EGFR inhibitors, particularly in the context of EGFR triple mutants.

The differential effect of treatment by smoking was not explained by TP53 mutation or other molecular alterations examined. Molecular mechanisms of acquired resistance were detected but no novel molecular alterations were identified in the combination arm.

Osimertinib, the third-generation irreversible EGFR-TKI, has been approved for the treatment of NSCLC patients with the EGFRT790M mutation...In this review, we discuss the discovery of novel fourth-generation EGFR TKIs, medicinal chemistry approaches and the strategies to overcome the C797S mutations. In vitro activities of EGFR-TKIs (2019-2024) against mutant EGFR TK, anti-proliferative activities, structural modifications, binding modes of the inhibitors and in vivo efficacies in animal models are discussed here.

Conclusions : This pilot study using a unique cohort of EGFR ex20+ NSCLC patients treated with high dose Osimertinib highlights the complexity of variant dynamics during treatment and disease progression, suggesting a potential link between changed levels of variants detected at progression. Potential resistance mechanisms were shown in 11/18 patients using ctDNA.

Conclusions : To our knowledge, this is the largest liquid biopsy analysis comparing common/uncommon ex19dels in NSCLC and shows similar genomic findings across groups. Further work should be done to explore additional genomic and non-genomic factors to aid in patient selection for EGFR TKIs for uncommon findings.

Ami+laz had significantly lower rates of EGFR and MET resistance alterations with trends for lower rates of TP53 resistance mutations and RB1 loss compared with osi. These initial findings suggest that first-line ami+laz is changing the biology of acquired resistance and demonstrate clear proof of mechanism with potent inhibition of resistance via the EGFR and MET pathways.

CRISPR-mediated PDK1 knockout effectively inhibited tumor formation in xenograft models. Our study established a clear link between the EGFR C797S mutation and elevated PDK1 expression, opening new avenues for the discovery of targeted therapies and improving our understanding of the roles of EGFR mutations in cancer progression.

Finally, C6 inhibited tumor growth in the H1975-TM xenograft tumor model effectively and safely. This study identifies a novel and potent EGFR PROTAC to overcome Osimertinib resistance mediated by C797S mutation.

Osimertinib has become the first globally accessible third-generation EGFR inhibitor, representing one of the most advanced developments in non-small-cell lung cancer (NSCLC) therapy...These degraders compared with EGFR inhibitors showed better efficiency in their cellular potency, inhibition, and toxicity profiles. In this review, we first introduce the structural properties of EGFR, the resistance, and mutations of EGFR, and then mainly focus on the recent advances of EGFR-targeting degraders along with its advantages and outstanding challenges.

Mechanism studies revealed that 14o was a potent EGFR L858R/T790M/C797S and EGFR Del19/T790M/C797S kinase inhibitor, which could downregulate the protein phosphorylation of EGFR and m-TOR signaling pathways, arrest cell cycle at G2/M phase by affecting the expression of CDC25C, and promote cell apoptosis by regulating the expression of cleaved caspase-3. In summary, 14o could serve as a promising deuterated compound for the development of highly efficient anticancer agents.

P1, N=751, Active, not recruiting, Janssen Research & Development, LLC | Trial completion date: Dec 2024 --> Jun 2025

Here, we reported two cases with NSCLC who initially harbored an EGFR-sensitive mutation and were both treated with osimertinib, a third-generation TKI. Our findings suggested that a combined regimen of brigatinib and cetuximab could serve as a potentially life-saving therapeutic strategy for critically ill patients with NSCLC, particularly those demonstrating EGFR p.C797S-mediated resistance. Further studies, however, are required to validate and expand upon these promising findings.

Structures show that BI-4020 is likely rendered selective due to interactions with the kinase domain hinge region as well as T790M, akin to Osimertinib. Additionally, BI-4020 is also rendered more potent due to its constrained macrocycle geometry as well as additional H-bonds to conserved K745 and T845 residues in both active and inactive conformations. These findings taken together show how this novel macrocyclic inhibitor is both highly potent and selective for mutant EGFR in a reversible mechanism and motivate structure- inspired approaches to developing targeted therapies in medicinal oncology.

Regrettably, the patient eventually died from heart disease. This report provides the first reported evidence for the use of furmonertinib and intrathecal pemetrexed chemotherapy in NSCLC patients harboring EGFR R776S/C797S/L858R mutations who progressed on previous EGFR-TKIs.

In 73% of participants, loss of T790M ctDNA is observed at progression and no participants have evidence of the EGFR C797S resistance mutation following the alternating regimen. These findings highlight the challenges of treatment strategies designed to modulate clonal evolution and the clinical importance of resistance mechanisms beyond suppression of selected genetic mutations in driving therapeutic escape to highly potent targeted therapies.

Brigatinib-based therapy was effective against osimertinib-resistant EGFR C797S mutants and is undergoing clinical studies. Molecular dynamics simulation revealed the binding mode and affinity between BI-4020 and EGFR mutants. This study identified potential therapeutic strategies using the new-generation macrocyclic EGFR inhibitor to overcome the emerging ultimate resistance mutants.

At concentration of 10 μM, A9 can be employed as the fourth-generation of EGFR inhibitors with the ability to overcome the C797S drug resistance since it can suppress EGFRDel19/T790M/C797S cells and kinase by 98.90% and 85.88%, respectively. Moreover, the tumor-bearing nude mice experiment further shows that A9 can significantly inhibit the growth of tumor in vivo, with the tumor inhibition rate (TIR) of 55.92%, which was equivalent to the positive group. After that, from the result of HE staining experiment and blood biochemical analysis experiment, A9 show low toxicity and good safety, which is worthy of further research and development.

Compound mutations responded better than single mutations for each PACC mutation. Table: 24P PACC mutations Guardant360 Retrospective clinical response data Case # Percent First-gen TKI Second-gen TKI Third-gen TKI ORR N ORR N ORR N G719 Single 191 26.8% 39% 310 56% 248 33% 36 Compound 521 73.2% 42% 52 77% 77 59% 27 S768 Single 44 13.1% 31% 29 48% 46 33% 9 Compound 291 86.9% 54% 11 63% 52 59% 17 G709 Single 6 2.9% 0% 5 50% 6 50% 4 Compound 201 97.1% 43% 7 62% 16 83% 6 Conclusions Compared to classical EGFR mutations, PACC mutations frequently occur as compound mutations, and tend to have improved response to EGFR TKIs than single PACC mutations.

EGFR-C797S in cis to all EGFR mutations evaluated generated dependent cells that were resistant to the covalent EGFR tyrosine kinase inhibitors mobocertinib, zipalertinib, furmonertinib, sunvozertinib, poziotinib, and osimertinib. This report highlights that poziotinib and mobocertinib are susceptible to on-target resistance mediated by EGFR-T790M or -C797S in the background of the most prevalent EGFR exon 20 insertion mutations. Furmonertinib, sunvozertinib, and to a less extent zipalertinib can overcome EGFR-T790M compound mutants, whereas EGFR-C797S leads to covalent inhibitor cross-resistance-robust data that support the limitations of mobocertinib and should further spawn the development of next-generation covalent and reversible EGFR exon 20 insertion mutation active inhibitors with favorable therapeutic windows that are less vulnerable to on-target resistance.

P1/2, N=190, Active, not recruiting, Blueprint Medicines Corporation | Recruiting --> Active, not recruiting

P1/2, N=200, Recruiting, Black Diamond Therapeutics, Inc. | Phase classification: P1 --> P1/2 | N=120 --> 200

These results suggest that T6496 may mitigate EGFR resistance caused by T790M or C797S mutations. Moreover, the AO staining assay, JC-1 staining, ROS experiment and hemolytic toxicity evaluation revealed that T6496 could induce apoptosis in H1975 cell lines in a time-dependent and concentration-dependent manner, and is a potential compound for further structural optimization.Communicated by Ramaswamy H. Sarma.

P1/2, N=200, Recruiting, Taiho Oncology, Inc.

The case showed that individualized treatment aided by D ~ Sense ex-vivo viability assay can be a viable option for patients with advanced lung adenocarcinoma with pleural effusions.

The first-generation of drugs such as gefitinib bind reversibly and were followed by a second-generation such as dacomitinib that harbor an acrylamide moiety that forms a covalent bond with C797 in the ATP binding pocket...A third generation of drugs, such as osimertinib were developed which were effective against T790M EGFR in which an acrylamide moiety forms a covalent bond with C797, although resistance has emerged by mutation to S797...A number of acrylamide containing fragments were identified that selectively reacted with C775. One of these acrylamides was optimized to a highly selective inhibitor with sub-1 μM activity, that is active against T790M, C797S mutant EGFR independent of ATP concentration, providing a potential new strategy for pan-EGFR mutant inhibition.

Importantly, JC-010a abolished acquired resistance induced by targeted therapies: in KRAS-mutant cancers, JC-010a abrogated selumetinib-induced adaptive resistance mediated by RTK/SHP2; in BCR-ABL-driven leukemia cells, we demonstrated JC-010a inhibited BCR-ABL T315I mutation-mediated imatinib resistance and proposed a novel mechanism of JC-010a involving the disrupted co-interaction of SHP2, BCR-ABL, and Hsp90; in non-small cell lung cancer (NSCLC) cells, JC-010a inhibited both EGFR T790M/C797S mutation and alternate RTK-driven resistance to gefitinib or osimertinib; importantly, we first proposed a novel potential therapeutic strategy for RET-rearranged cancer, we confirmed that JC-010a monotherapy inhibited cell resistance to BLU-667, and JC-010a/BLU-667 combination prolonged anticancer response both in vivo and in vitro cancer models by inhibiting the alternate MET activation-induced RAS/MAPK reactivation, thereby promoting cancer cell apoptosis. These findings suggested that JC-010a was a novel selective SHP2 allosteric inhibitor, and combing JC-010a with current targeted therapy agents provided a promising therapeutic approach for clinical resistant cancers.

The third-generation kinase inhibitor Osimertinib is currently playing a very vital role in the treatment of NSCLC...Finally, the binding mechanism and important hydrogen-bonding residues during unbinding of the inhibitors were fully elucidated. This study provides insight into the binding of the receptor-orthosteric inhibitor-allosteric inhibitor, which can be helpful for further design of novel inhibitors that have a better inhibitory action.

P1, N=751, Active, not recruiting, Janssen Research & Development, LLC | Trial completion date: Jan 2024 --> Dec 2024

The detection of T790M at PD after osimertinib initiation was a significant independent prognostic factor for predicting shorter prognosis, and the presence of major EGFR mutations at pretreatment and PD was closely linked to worse survival after osimertinib initiation. Molecular testing based on ctDNA is helpful for predicting outcomes of osimertinib treatment in T790M-positive NSCLC after previous EGFR-TKI treatment.

Allelic context could define four EGFR C797X-mutant NSCLC subtypes with heterogeneous genetic landscape and distinct clinical outcomes. Subsequent treatments further complicate the scenario through subtype switching.

P1, N=751, Active, not recruiting, Janssen Research & Development, LLC | Recruiting --> Active, not recruiting

Resistance to osimertinib demonstrated to be highly heterogeneous, with MET amplification the main mechanism. Plasma genotyping is a relevant complementary tool which might integrate tissue analysis for the study of resistance mechanisms.