Molecular mechanisms of acquired resistance to third-generation EGFR-TKIs in EGFR T790M-mutant lung cancer

Chidamide improves gefitinib treatment outcomes in NSCLC by attenuating recruitment and immunosuppressive function of myeloid-derived suppressor cells

Clinical resistance to EGFR tyrosine kinase inhibitors in non-small-cell lung cancer (NSCLC) remains a significant challenge. Recent studies have indicated that the number of myeloid-derived suppressor cells (MDSCs) increases following gefitinib treatment, correlating with a poor patient response in NSCLC. Our study revealed that gefitinib treatment stimulates the production of CCL2, which subsequently enhances monocyte (M)-MDSC migration to tumor sites. Chidamide, a selective inhibitor of the histone deacetylase subtype, counteracted the gefitinib-induced increase in CCL2 levels in tumor cells. Additionally, chidamide down-regulated the expression of CCR2 in M-MDSCs, inhibiting their migration. Furthermore, chidamide attenuated the immunosuppressive function of M-MDSCs both alone and in combination with gefitinib. Chidamide also alleviated tumor immunosuppression by reducing the number of M-MDSCs in LLC-bearing mice, thereby enhancing the antitumor efficacy of gefitinib. In conclusion, our findings suggest that chidamide can improve gefitinib treatment outcomes, indicating that MDSCs are promising targets in NSCLC.

MUC1-C Is a Common Driver of Acquired Osimertinib Resistance in NSCLC

INTRODUCTION

Osimertinib is an irreversible EGFR tyrosine kinase inhibitor approved for the first-line treatment of patients with metastatic NSCLC harboring EGFR exon 19 deletions or L858R mutations. Patients treated with osimertinib invariably develop acquired resistance by mechanisms involving additional EGFR mutations, MET amplification, and other pathways. There is no known involvement of the oncogenic MUC1-C protein in acquired osimertinib resistance.

METHODS

H1975/EGFR (L858R/T790M) and patient-derived NSCLC cells with acquired osimertinib resistance were investigated for MUC1-C dependence in studies of EGFR pathway activation, clonogenicity, and self-renewal capacity.

RESULTS

We reveal that MUC1-C is up-regulated in H1975 osimertinib drug-tolerant persister cells and is necessary for activation of the EGFR pathway. H1975 cells selected for stable osimertinib resistance (H1975-OR) and MGH700-2D cells isolated from a patient with acquired osimertinib resistance are found to be dependent on MUC1-C for induction of (1) phospho (p)-EGFR, p-ERK, and p-AKT, (2) EMT, and (3) the resistant phenotype. We report that MUC1-C is also required for p-EGFR, p-ERK, and p-AKT activation and self-renewal capacity in acquired osimertinib-resistant (1) MET-amplified MGH170-1D #2 cells and (2) MGH121 Res#2/EGFR (T790M/C797S) cells. Importantly, targeting MUC1-C in these diverse models reverses osimertinib resistance. In support of these results, high MUC1 mRNA and MUC1-C protein expression is associated with a poor prognosis for patients with EGFR-mutant NSCLCs.

CONCLUSIONS

Our findings reveal that MUC1-C is a common effector of osimertinib resistance and is a potential target for the treatment of osimertinib-resistant NSCLCs.

Treatment Strategies for Non-Small Cell Lung Cancer with Common EGFR Mutations: A Review of the History of EGFR TKIs Approval and Emerging Data

The development of targeted therapies over the past two decades has led to a dramatic change in the management of EGFR-mutant non-small cell lung cancer (NSCLC). While there are currently five approved EGFR tyrosine kinase inhibitors (TKIs) for treating EGFR-mutant NSCLC in the first-line setting, therapy selection after progression on EGFR TKIs remains complex. Multiple groups are investigating novel therapies and drug combinations to determine the optimal therapy and treatment sequence for these patients. In this review, we summarize the landmark trials and history of the approval of EGFR TKIs, their efficacy and tolerability, and the role of these therapies in patients with central nervous system metastasis. We also briefly discuss the mechanisms of resistance to EGFR TKIs, ongoing attempts to overcome resistance and improve outcomes, and finalize by offering treatment sequencing recommendations.

Sequence-dependent synergistic effect of aumolertinib-pemetrexed combined therapy on EGFR-mutant non-small-cell lung carcinoma with pre-clinical and clinical evidence

BACKGROUND

Inevitably developed resistance of the third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) limited its clinical benefit on non-small cell lung cancer (NSCLC). Upfront combination therapy is promising to prevent this resistance. Compelling clinical evidence indicated the failure of third-generation EGFR TKIs combined with either immunotherapy or antiangiogenic agents. In comparison, combined treatment of third-generation EGFR TKIs and chemotherapy might be a favorable choice. Herein, we systematically analyzed and compared the effects of pemetrexed and a novel third-generation EGFR TKI aumolertinib combined in different sequences, subsequently revealed the potential mechanisms and proved the optimal combination schedule with clinical retrospective study.

METHODS

Three combination schedules involving pemetrexed and aumolertinib in different sequences were developed. Their inhibition effects on cell proliferation and metastasis were firstly compared upon three human NSCLC cell lines in vitro, by cell counting kit-8, colony formation, wound healing and transwell assays respectively. Further evaluation in vivo was proceeded upon H1975 and HCC827 xenograft model. Gene and protein expression were detected by Q-PCR and western blot. Drug concentration was determined by LC-MS/MS. VEGF secretion was determined by ELISA. Tumor vessel was visualized by immunofluorescence. Lastly, a clinical retrospective study was raised with 65 patients' data.

RESULTS

The combination of pemetrexed and aumolertinib exhibited a sequence-dependent and EGFR mutant-dependent synergistic effect in vitro and in vivo. Only treatment with aumolertinib following pemetrexed (P-A) exhibited synergistic effect with stronger anti-tumor growth and anti-metastasis ability than monotherapy and also other combination sequences. This synergism could exclusively be observed in H1975 and HCC827 but not A549. Pathway analysis showed that P-A significantly enhanced the suppression of EGFR pathway. In addition, our results intriguingly found an obvious reduction of VEGF secretion and the accompanying normalization of the intratumor vessel, consequently increasing intratumoral accumulation of pemetrexed in P-A group. Finally, the clinical retrospective study verified the synergistic effect of P-A combination by significantly superior tumor response than aumolertinib monotherapy.

CONCLUSION

Aumolertinib-pemetrexed combined therapy is promising for EGFR mutant NSCLC but only in right administration sequence. P-A could become an advantageous combination strategy in clinical with synergistic inhibition of tumor growth and metastasis.

Mapping the evolution of T cell states during response and resistance to adoptive cellular therapy

To elucidate mechanisms by which T cells eliminate leukemia, we study donor lymphocyte infusion (DLI), an established immunotherapy for relapsed leukemia. We model T cell dynamics by integrating longitudinal, multimodal data from 94,517 bone marrow-derived single T cell transcriptomes in addition to chromatin accessibility and single T cell receptor sequencing from patients undergoing DLI. We find that responsive tumors are defined by enrichment of late-differentiated T cells before DLI and rapid, durable expansion of early differentiated T cells after treatment, highly similar to "terminal" and "precursor" exhausted subsets, respectively. Resistance, in contrast, is defined by heterogeneous T cell dysfunction. Surprisingly, early differentiated T cells in responders mainly originate from pre-existing and novel clonotypes recruited to the leukemic microenvironment, rather than the infusion. Our work provides a paradigm for analyzing longitudinal single-cell profiling of scenarios beyond adoptive cell therapy and introduces Symphony, a Bayesian approach to infer regulatory circuitry underlying T cell subsets, with broad relevance to exhaustion antagonists across cancers.

A Large Real-World Study on the Effectiveness of the Combined Inhibition of EGFR and MET in EGFR-Mutant Non-Small-Cell Lung Cancer After Development of EGFR-TKI Resistance

Background

MET proto-oncogene amplification (amp) is an important mechanism underlying acquired resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs). However, the optimal treatment strategy after acquiring MET-amp-mediated EGFR-TKI resistance remains controversial. Our study compared three treatment strategies for patients with EGFR-mutant non-small-cell lung cancer (NSCLC) who were detected with MET-amp at EGFR-TKI progression using next-generation sequencing.

Methods

Of the 70 patients included in the study, 38 received EGFR-TKI + crizotinib, 10 received crizotinib monotherapy, and 22 received chemotherapy. Clinical outcomes and molecular profiles were analyzed.

Results

The objective response rate was 48.6% for EGFR-TKI + crizotinib group, 40.0% for crizotinib monotherapy group, and 18.2% for chemotherapy group. Patients who received EGFR-TKI + crizotinib had significantly longer progression-free survival than those who received crizotinib or chemotherapy (5.0 vs. 2.3 vs. 2.9 months, p = 0.010), but overall survival was comparable (10.0 vs. 4.1 vs. 8.5 months, p = 0.088). TP53 mutation (58.5%) and EGFR-amp (42.9%) were frequent concurrent mutations of the cohort. Progression-free survival was significantly longer for patients with either concurrent TP53 mutation (n = 17) (6.0 vs. 2.3 vs. 2.9 months, p = 0.009) or EGFR-amp (n = 13) (5.0 vs. 1.2 vs. 2.4 months, p = 0.016) in the EGFR-TKI + crizotinib group than the other two regimen. Potential acquired resistance mechanisms to EGFR-TKI + crizotinib included EGFR-T790M (n = 2), EGFR-L718Q (n = 1), EGFR-S645C (n = 1), MET-D1228H (n = 1), BRAF-V600E (n = 1), NRAS-Q61H (n = 1), KRAS-amp (n = 1), ERBB2-amp (n = 1), CDK4-amp (n = 1), and MYC-amp (n = 1).

Conclusion

Our study provides real-world clinical evidence from a large cohort that simultaneous inhibition of EGFR and MET could be a more effective therapeutic strategy for patients with MET-amp acquired from EGFR-TKI therapy.

Sequential treatment of afatinib and osimertinib or other regimens in patients with advanced non-small-cell lung cancer harboring EGFR mutations: Results from a real-world study in South Korea

OBJECTIVES

The optimal sequence for the administration of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) for treating non-small cell lung cancer (NSCLC) is still unclear. This study aimed to evaluate the efficacy of sequential afatinib and osimertinib treatment in patients with NSCLC harboring EGFR mutations.

MATERIALS AND METHODS

Electronic records of patients with EGFR-mutated NSCLC, who were administered afatinib and osimertinib (group A) or other chemotherapy (group B) between October 2014 and 2019, across 16 hospitals in South Korea were reviewed. The primary outcome, time on treatment (TOT), secondary outcome, and overall survival (OS) were estimated using the Kaplan-Meier method and log-rank test. Multivariate analyses were performed using the Cox proportional hazards model.

RESULTS

Of the 737 patients who received frontline afatinib treatment, 324 with complete records were selected (group A: 126, group B: 198). All patients in group A were T790M positive after afatinib, while patients in group B were all negative or unknown. The median TOT was 35.4 months (95% confidence interval [CI]: 27.7-45.6) in group A and 20.8 months (95% CI: 19.4-24.0) in group B. The median TOT with afatinib was 13.0 months (95% CI: 12.0-13.9) overall and 15.7 months (95% CI: 13.9-17.3) in group A. The 2- and 3-year survival rates were 86.0 and 69.3% in group A and 75.9 and 55.3% in group B, respectively.

CONCLUSION

Sequential afatinib and osimertinib treatment resulted in better survival rates than treatment with afatinib followed by other chemotherapies.

Deciphering Complex Mechanisms of Resistance and Loss of Potency through Coupled Molecular Dynamics and Machine Learning

Drug resistance threatens many critical therapeutics through mutations in the drug target. The molecular mechanisms by which combinations of mutations, especially those remote from the active site, alter drug binding to confer resistance are poorly understood and thus difficult to counteract. A machine learning strategy was developed that coupled parallel molecular dynamics simulations with experimental potency to identify specific conserved mechanisms underlying resistance. Physical features were extracted from the simulations, analyzed, and integrated into one consistent and interpretable elastic network model. To rigorously test this strategy, HIV-1 protease variants with diverse mutations were used, with potencies ranging from picomolar to micromolar to the drug darunavir. Feature reduction resulted in a model with four specific features that predicts for both the training and test sets inhibitor binding free energy within 1 kcal/mol of the experimental value over this entire range of potency. These predictive features are physically interpretable, as they vary specifically with affinity and diagonally transverse across the protease homodimer. This physics-based strategy of parallel molecular dynamics and machine learning captures mechanisms by which complex combinations of mutations confer resistance and identify critical features that serve as bellwethers of affinity, which will be critical in future drug design.

Overcoming therapy resistance in EGFR-mutant lung cancer

Tyrosine kinase inhibitors (TKIs) have dramatically changed the clinical prospects of patients with non-small cell lung cancer harboring epidermal growth factor receptor (EGFR)-activating mutations. Despite prolonged disease control and high tumor response rates, all patients eventually progress on EGFR TKI treatment. Here, we review the mechanisms of acquired EGFR TKI resistance, the methods for monitoring its appearance, as well as current and future efforts to define treatment strategies to overcome resistance.

Multiple mutations within individual oncogenes

Recent studies of the cancer genome have identified numerous patients harboring multiple mutations (MM) within individual oncogenes. These MM (de novo MM) in cis synergistically activate the mutated oncogene and promote tumorigenesis, indicating a positive epistatic interaction between mutations. The relatively frequent de novo MM suggest that intramolecular positive epistasis is widespread in oncogenes. Studies also suggest that negative and higher-order epistasis affects de novo MM. Comparison of de novo MM and MM associated with drug-resistant secondary mutations (secondary MM) revealed several similarities with respect to allelic configuration, mutational selection and functionality of individual mutations. Conversely, they have several differences, most notably the difference in drug sensitivities. Secondary MM usually confer resistance to molecularly targeted therapies, whereas several de novo MM are associated with increased sensitivity, implying that both can be useful as therapeutic biomarkers. Unlike secondary MM in which specific secondary resistant mutations are selected, minor (infrequent) functionally weak mutations are convergently selected in de novo MM, which may provide an explanation as to why such mutations accumulate in cancer. The third type of MM is MM from different subclones. This type of MM is associated with parallel evolution, which may contribute to relapse and treatment failure. Collectively, MM within individual oncogenes are diverse, but all types of MM are associated with cancer evolution and therapeutic response. Further evaluation of oncogenic MM is warranted to gain a deeper understanding of cancer genetics and evolution.

KRAS amplification in metastatic colon cancer is associated with a history of inflammatory bowel disease and may confer resistance to anti-EGFR therapy

Mutations in RAS occur in 30-50% of metastatic colorectal carcinomas (mCRCs) and correlate with resistance to anti-EGFR therapy. Consequently, mCRC biomarker guidelines state RAS mutational testing should be performed when considering EGFR inhibitor treatment. However, a small subset of mCRCs are reported to harbor RAS amplification. In order to elucidate the clinicopathologic features and anti-EGFR treatment response associated with RAS amplification, we retrospectively reviewed a large cohort of mCRC patients that underwent targeted next-generation sequencing and copy number analysis for KRAS, NRAS, HRAS, BRAF, and PIK3CA. Molecular testing was performed on 1286 consecutive mCRC from 1271 patients as part of routine clinical care, and results were correlated with clinicopathologic findings, mismatch repair (MMR) status and follow-up. RAS amplification was detected in 22 (2%) mCRCs and included: KRAS, NRAS, and HRAS for 15, 5, and 2 cases, respectively (6-21 gene copies). Patients with a KRAS-amplified mCRC were more likely to report a history of inflammatory bowel disease (p < 0.001). In contrast, mutations in KRAS were associated with older patient age, right-sided colonic origin, low-grade differentiation, mucinous histology, and MMR proficiency (p ≤ 0.017). Four patients with a KRAS-amplified mCRC and no concomitant RAS/BRAF/PIK3CA mutations received EGFR inhibitor-based therapy, and none demonstrated a clinicoradiographic response. The therapeutic impact of RAS amplification was further evaluated using a separate, multi-institutional cohort of 23 patients. Eight of 23 patients with KRAS-amplified mCRC received anti-EGFR therapy and all 8 patients exhibited disease progression on treatment. Although the number of KRAS-amplified mCRCs is limited, our data suggest the clinicopathologic features associated with mCRC harboring a KRAS amplification are distinct from those associated with a KRAS mutation. However, both alterations seem to confer EGFR inhibitor resistance and, therefore, RAS testing to include copy number analyses may be of consideration in the treatment of mCRC.

Disruption of the EGFR-SQSTM1 interaction by a stapled peptide suppresses lung cancer via activating autophagy and inhibiting EGFR signaling

Despite the success of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in the treatment of non-small cell lung cancer (NSCLC) harboring EGFR-activating mutations, intrinsic or acquired resistance remains the major obstacle to long-term disease remission. Defective autophagy has been reported as an EGFR-TKI resistance mechanism. However, how EGFR regulate autophagic flux are still not fully understood. Here we found that EGFR-stimulated phosphorylation of SQSTM1 at tyrosine 433 induces dimerization of its UBA domain, which disturbs the sequestration function of SQSTM1 and causes autophagic flux blocking. SAH-EJ2, a staple optimized EGFR-derived peptide, showed enhanced in vitro and in vivo antitumor activity against NSCLC than the prototype regardless of EGFR mutation status. Mechanistically, SAH-EJ2 disrupts the EGFR-SQSTM1 interaction and protects against EGFR-induced SQSTM1 phosphorylation, which hinders the dimerization of the SQSTM1 UBA domains and restores SQSTM1 cargo function. Moreover, SAH-EJ2 suppresses EGFR activity by blocking its dimerization and reducing its protein stability, which reciprocally activates the core autophagy machinery. Our observations reveal that disturbing the EGFR-SQSTM1 interaction by SAH-EJ2 confers a potential strategy in the treatment of NSCLC through suppressing EGFR signalling and activating autophagy simultaneously.