3rd Generation Tyrosine Kinase Inhibitors Research Articles

PrPC controls epithelial-to-mesenchymal transition in EGFR-mutated NSCLC: implications for TKI resistance and patient follow-up

Patients with EGFR-mutated non-small cell lung cancer (NSCLC) benefit from treatment with tyrosine kinase inhibitors (TKI) targeting EGFR. Despite improvements in patient care, especially with the 3rd generation TKI osimertinib, disease relapse is observed in all patients. Among the various processes involved in TKI resistance, epithelial-to-mesenchymal transition (EMT) is far from being fully characterized. We hypothesized that the cellular prion protein PrPC could be involved in EMT and EGFR-TKI resistance in NSCLC. Using 5 independent lung adenocarcinoma datasets, including our own cohort, we document that the expression of the PRNP gene encoding PrPC is associated with EMT. By manipulating the levels of PrPC in different EGFR-mutated NSCLC cell lines, we firmly establish that the expression of PrPC is mandatory for cells to maintain or acquire a mesenchymal phenotype. Mechanistically, we show that PrPC operates through an ILK-RBPJ cascade, which also controls the expression of EGFR. Our data further demonstrate that PrPC levels are elevated in EGFR-mutated versus wild-type tumours or upon EGFR activation in vitro. In addition, we provide evidence that PRNP levels increase with TKI resistance and that reducing PRNP expression sensitizes cells to osimertinib. Finally, we found that plasma PrPC levels are increased in EGFR-mutated NSCLC patients from 2 independent cohorts and that their longitudinal evolution mirrors that of disease. Altogether, these findings define PrPC as a candidate driver of EMT-dependent resistance to EGFR-TKI in NSCLC. They further suggest that monitoring plasma PrPC levels may represent a valuable non-invasive strategy for patient follow-up and warrant considering PrPC-targeted therapies for EGFR-mutated NSCLC patients with TKI failure.

What is a bad ALK? A scoping review of molecular markers of poor prognosis.

e20530 Background: Patients with non-small cell lung cancer (NSCLC) with anaplastic lymphoma kinase ( ALK) rearrangements derive a significant and durable clinical benefit from tyrosine kinase inhibitors (TKI). However, a portion of patients have progressive disease as their best response and progress to death much earlier than expected which is termed primary resistance. This scoping review aims to summarize the known molecular mechanisms that underlie this lethal ALK phenotype. Methods: We performed a systematic scoping review from scientific databases such as Ovid Medline, Ovid Embase, and Cochrane Central Register of Controlled Trials. Data was extracted from the database inception to March 13, 2023. Studies included molecular markers of poor prognosis, with a focus on TP53, variant 3 re-arrangements, and reports of poor clinical response to TKIs (defined as progression-free survival less than 3 months on 1st line TKI or overall survival less than 2 years from exposure to 1st line TKI). 2nd generation and 3rd generation ALK TKI clinical trial data were also included. Results: A total of 4360 studies were screened and 136 studies were included. Numerous studies implicated the negative prognostic role of variant 3 likely mediated through the acquisition of on-target resistance mutations compared to other variants. TP53 mutations were also associated with a worse prognosis and implicated with greater chromosomal instability and mutational burden. Furthermore, reports of both variant 3 and TP53 mutations together were associated with even worse survival suggesting both molecular mechanisms combined can confer primary resistance phenotype. Other mediators of primary resistance included aberrations in cell cycle regulators such as CDKN2A/B loss, mutations in cell signalling pathways such as the PI3K/ AKT/mTOR pathway, deficiencies in DNA repair mechanisms, and uncommon fusion partners. Consistent with these prior studies, comprehensive genomic analysis from clinical trial data of 2nd generation and 3rd generation TKIs was unable to identify a singular genomic signature that underlies this lethal phenotype. However, a general trend from the literature suggested that the combination of multiple aberrations is likely necessary to confer a primary resistance phenotype, though the relative contribution of each somatic mutation likely will vary. Conclusions: This scoping review highlights that in NSCLC, the lethal ALK phenotype is likely composed of a heterogeneous population of various combinations of poor prognostic factors including variant 3, mutations in cell cycle regulators and other aberrations in cell signalling pathways. There remains an unmet need for a genomic assay to integrate all these various molecular markers to predict the lethal ALK phenotype.

OSIRAM-1/TORG1833: Overall survival results of a randomized phase II study of osimertinib plus ramucirumab versus osimertinib alone as initial chemotherapy for EGFR mutation-positive non-squamous non-small cell lung cancer.

8613 Background: Dual inhibition of the EGFR/VEGF pathways has demonstrated superior efficacy with 1st generation EGFR tyrosine kinase inhibitor (TKI) in patients with non-small cell lung cancer (NSCLC) harboring EGFR mutations. This study aims to evaluate the efficacy and safety of combining osimertinib (Osi), a 3rd generation TKI considered the standard of care, with ramucirumab (Ram). We have previously shown the result of progression free survival (PFS) as a primary endpoint, the median PFS was 20.0 months for Osi+Ram and 24.0 months for Osi, hazard ratio of 1.054 (95% CI 0.674-1.648). In further analyses, we aimed to examine the effects of this combination therapy on overall survival (OS). Methods: Previously untreated EGFR mutation-positive advanced non-squamous NSCLC patients with a performance status of 0 or 1 were eligible. Asymptomatic and/or treated brain metastases were included. Eligible patients were randomized at a 1:1 ratio to receive Osi (80mg) every day either without or with Ram (10mg/kg) every 2 weeks until disease progression or unacceptable toxicity, stratified according to gender and the type of EGFR mutation (exon 19 deletion, L858R). The primary endpoint was PFS assessed by the independent blinded radiologic reviewer. Secondary endpoints included PFS assessed locally, objective response rate (ORR), disease control rate (DCR), duration of response (DOR), OS and safety. Results: Between November 2018 and April 2020, 122 patients (Osi+Ram: 59, Osi: 63) were enrolled. The patients' characteristics were well balanced. 59% were females, and 61% had an exon 19 deletion. Median age was 70 years old (range, 29-86). With a median follow up of 36.0 months, the median OS was 43.4 months (95% CI 36.5-N.R.) for Osi+Ram and N.R. (95% CI 41.3-N.R.) for Osi, resulting in a hazard ratio of 1.159 (95% CI 0.645-2.083, p = 0.62). Median treatment duration for Ram was 140 (14-1239) days. Ram was discontinued in 45 patients (76%) by the treatment related adverse effects. Common reasons for Ram discontinuation were platelet count decreased (n=14), proteinuria (n=12), neutrophil count decreased (n=11), pneumonitis (n=3), bleeding (n=3) and infection (n=3). Pneumonitis was observed in 16% in Osi, 9% in Osi+Ram, with grade 3 observed in 2% of both arms. Conclusions: Both treatment arms demonstrated sustained OS over 43 months. However, this study did not show an advantage of biweekly Ram administration with Osi in terms of PFS and OS. Notably, there was surpassed increase of early discontinuation of Ram due to higher adverse events. Clinical trial information: 2080224085 .

Abstract 5874: Phenotypic plasticity of TKI resistance reprograms cytoskeleton organization through cadherin-catenin and integrin pathways

Abstract The acquired resistance to EGFR tyrosine kinase inhibitors (TKIs) restricts its clinical utility. Clinically, acquired resistance has been highly associated with epithelial-mesenchymal transition (EMT) traits. In this study, we characterized shared phenotypic plasticity features of TKI-resistant cells and aimed to find its key driver in three different cell lines harboring mutant EGFR. In vitro resistance cell lines were generated by dose-escalation exposure to osimertinib, a 3rd generation TKI, for more than 2 months. We employed canonical markers (E-cadherin, vimentin, pan-cytokeratin, and N-cadherin) along with additional markers (EpCAM and fibronectin) to define the EMT status of resistant cells. Moreover, cytoskeleton architecture (F-actin and Vimentin) was utilized to clarify the types of cell motility. Transcriptomics analysis illustrated enriched pathways at focal adhesion and adherens junction. Loss of adherens junction-related catenin (α-E-catenin, β-catenin, γ-catenin, p120 catenin) and aberrant activation of focal adhesion-related protein (p-FAK Y397 and Y576/57, p-Src Y416) confirmed the transcriptomics analysis of reduced contact inhibition and cell polarity. The resulting migration mode of resistant cells highly resembles ameboid movement. Mechanistically, we identified that YTHDF3, a metastasis-promoting regulator of mRNA methylation, destabilizes the mRNA of E-cadherin. Depletion of YTHDF3 in resistant cells reversed the cadherin-catenin pathway and distribution of vimentin and f-actin. In conclusion, resistant cells display ameboid-like movement resulting from loss of contact inhibition and aberrant activation of focal adhesion. Mechanistically, we identified that YTHDF3, a metastasis-promoting regulator of mRNA methylation, destabilizes the mRNA of E-cadherin. Depletion of YTHDF3 in resistant cells reversed the cadherin-catenin pathway and distribution of vimentin and f-actin. YTHDF3 serves as an RNA epitranscriptomic regulator that destabilizes CDH1 mRNA, thereby disrupting adherens junction formation and reducing integrin-mediated focal adhesion stabilization. Citation Format: Chun Ma, Jerry Chieh-Yu Chen, Mong-Lien Wang. Phenotypic plasticity of TKI resistance reprograms cytoskeleton organization through cadherin-catenin and integrin pathways [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5874.

Analysis of the effect of baseline detection and early clearance of ct-DNA, on survival outcomes among patients with advanced EGFR-mutant non-small cell lung cancer.

To determine if circulating tumor DNA (ct-DNA) dynamics of epidermal growth factor receptor (EGFR) mutation in plasma can identify asubset of patients with EGFR-mutant (EGFR- m) non-small cell lung cancer (NSCLC) with inferior survival outcomes, we analyzed and compared survival outcomes among patients with and without baseline presence and early clearance of EGFR ct-DNA in plasma. For 66patients newly dia-gnosed with EGFR- m NSCLC, plasma samples were collected at baseline and 1st response assessment at 12-24weeks for extraction of ct-DNA. Estimation of ct-DNA (EGFR exons 18, 19, 20and 21) was done using droplet digital polymerase chain reaction (dd-PCR) on the QX200ddPCR system (BioRad, USA). Patients with detectable EGFR ct-DNA at baseline (sample 1), with either undetectable or persistent detectable ct-DNA in sample 2were classified as clearers and non-clearers, respectively. Fifty-three patients received 1st/ 2nd generation EGFR tyrosine kinase inhibitors (TKIs) and 13received either 3rd generation TKI (osimertinib) or chemotherapy plus gefitinib. The baseline ct-DNA-positive group had more patients with extra thoracic disease (60.4vs. 48.5%). For the entire cohort, there was no difference in median progression-free survival (PFS) among baseline ct-DNA-negative (13.57months) vs. ct-DNA-positive patients (12.32months) (HR 0.74). There was asignificant improvement of PFS among early ct-DNA clearers vs. non-clearers (12.32vs. 9.92months; HR 0.57). For those treated with 1st/ 2nd generation EGFR TKIs, this improvement in median PFS among early ct-DNA clearers vs. non-clearers was more apparent (11.76vs. 6.8months; HR 0.34). Baseline detection of the presence of ct-DNA of EGFR mutation in plasma was not predictive of first-line PFS, but is associated with extra thoracic disease. Patients with EGFR mutation and persistence of ct-DNA at first follow-up have worse PFS and overall survival (OS) in comparison to those clearing the same in plasma, especially among those treated with 1st/ 2nd generation EGFR TKIs.

ASCL1 Drives Tolerance to Osimertinib in EGFR Mutant Lung Cancer in Permissive Cellular Contexts.

Analysis of residual disease following tyrosine kinase inhibitor treatment identified heterogeneous and context-specific mechanisms of drug tolerance in lung cancer that could lead to the development of strategies to forestall drug resistance. See related commentary by Rumde and Burns, p. 1188.

3rd-Generation Tyrosine Kinase-Inhibitors and Azacitidine Are Safe and Effective in Myeloid Blast-Phase Chronic Myeloid Leukaemia and Result in a High Proportion of Subjects in 2 nd Chronic Phase Able to Receive a Transplant

Background Myeloidblast phase of chronic myeloid leukemia (CML-MBP) has a terrible prognosis with a haemopoietic cell transplant the only likely cure. Probability of transplant success is markedly increased if someone can be returned to chronic phase. Purposes Study safety and efficacy of olverembatinib or ponatinib and azacitidine (AZA) in this setting. MethodsCML-MBP was diagnosed according to the WHO 2016 criteria. Ponatinib, 45 mg/d or olverembatinib, 30 mg every other d were combined with azacitidine, 75 mg/mE+2/d for 7 d in 28 d cycles. Subjects achieving 2 nd chronic phase received an allotransplant whereas others continued the therapy specified. 2 nd chronic phase was defined as < 10% blood and bone marrow blasts and no extra-medullary leukaemia for ≥ 4 w. Event-free survival (EFS) was defined as interval from therapy start to no response, progression to accelerated or blast phase or CML-related death. CML-related survival was defined as interval from therapy start to death from blast phase and survival, this interval to death from any cause. Haematologic, cytogenetic and molecular responses were monitored. Targeted DNA sequencing and whole RNA sequencing were done before therapy start. “MOVICS” package in R software was used for multi-omics integrated analyses and molecular sub-type classification. Cox regression models were used to identify co-variates associated with outcomes. The study was registered in Chinese Clinical Trial Registry (ChiCTR2200055887). Results 39 consecutive subjects were registered from October, 2020 to July, 2023. 21 were male. Median age was 50 years (Interquartile range [IQR], 33-54 years). 23 received olverembatinib; 16, ponatinib. Median follow-up was 10 months (mo) (IQR, 3-19 mo). 30 (77%) subjects achieved a 2 nd chronic phase after 1 cycle, 11 of whom received a transplant, 8 progressed to blast phase again; and 9 (23%) others had no response. 25 subjects died of progression (N = 19), transplant-related mortality (N = 3), COVID-19 (N = 2) or heart failure (N = 1). Median EFS, CML-related survival and survival were 4 (95% Confidence Interval [CI], 1-6) months, 12 (8-17) months and 11 (6-15) months. Subjects receiving a transplant had better EFS ( p= 0.03), CML-related survival ( p= 0.009) and survival ( p= 0.04) compared with non-transplant subjects ( Figure 1). Most treatment-related severe adverse events were tolerable and manageable including 25 subjects (65%) developing ≥ 4 grade neutropenia with or without thrombocytopenia except only 1 subject developing early death due to heart failure. In addition, 2 subjects experienced COVID-19 and died subsequently. In adjusted Cox regression analyses of genomic (N = 37) and transcriptomic (N = 34) data KRASmutation was significantly-associated with worse EFS ( p= 0.05), CML-related survival ( p< 0.001) and survival ( p= 0.009). TP53mutation was associated with worse CML-related survival ( p= 0.02) and survival ( p= 0.003). PFKFB3::LINC02649 fusion was associated with better EFS ( p= 0.001), CML-related survival ( p= 0.007) and survival ( p= 0.005). Based on these data 34 subjects were divided into 2 clusters. Subjects in cluster 2 (N = 14) had worse EFS ( p= 0.001), CML-related survival ( p= 0.008) and survival ( p= 0.005) compared with those in cluster 1 (N = 20). In differential gene expression analyses 1,564 genes were up-regulated and 1,000 down-regulated in cluster 2 compared with cluster 1. In KEGG analyses up-regulated genes were enriched in signaling pathways including cytokine-cytokine receptor interaction, cell adhesion molecules, natural-killer (NK) cell mediated cytotoxicity, primary immune deficiency and Toll-like receptor. Down-regulated genes were enriched in cell-cycle and DNA replication pathways. Conclusion s Olverembatinib or ponatinib combined with azacitidine is a safe and effective therapy of CML-MBP allowing many subjects to receive a transplant in 2 nd chronic phase. KRAS and TP53 mutations and PFKFB3::LINC02649 fusions had predictive impact on outcomes. Determining whether adding azacitidine to a 3 rd-generation TKI requires a randomized controlled trial.

Implementation of a knowledge-based mechanistic model of EGFR-mutant lung adenocarcinoma that considers tumor heterogeneity and metastases to reproduce disease progression upon EGFR-TKI administration.

e21190 Background: 16,4% of lung adenocarcinomas (LUAD) are presenting a mutation in the epidermal growth factor receptor (EGFR), resulting in its constitutive activation and leading to uncontrolled cell proliferation [1]. Tyrosine kinase inhibitors (TKI) have been developed to inhibit EGFR activity but the presence of metastases and resistance mutations explain the lack of durable response to the treatment [2]. Knowledge-based mechanistic models reproducing existing clinical trials, based on population characteristics, can be used to help the design of future clinical trials. In particular, they can inform on the best responders to given treatments. Methods: We developed a physiologically based pharmacokinetic model of osimertinib, a 3rd generation TKI, to account for the distribution of the drug in the primary tumor and metastases after oral administration. This model was then combined to a pathophysiological mechanistic model of EGFR-mutant LUAD to represent the impact of osimertinib on the signals arising from EGFR activation. The combined model outputs the evolution of the primary tumor and each metastasis to allow the evaluation of the patient progression according to the RECIST criteria. Furthermore, each tumor in the model is composed of several subclones each possessing their own set of mutations and therefore responding differently to the treatment. Data from the clinical trials FLAURA and AURA3, in which osimertinib was given respectively as first and second line, were used to calibrate the model. Visual predictive checks as well as statistical tests were performed to ensure the proper behavior of the model. Results: The model successfully reproduced the time to progression in an EGFR mutant LUAD population treated with osimertinib as first line or as second line. In addition, the model reproduced the causes of progression according to the RECIST criteria and the sites of apparition of new metastases (in lung, brain, liver and bone). Conclusions: Reproduction of real world data brings credibility to the model. This is essential to use the model as an investigational tool to provide relevant insights, potentially on the best responders to osimertinib. After validation with additional clinical patient level data, the model could be used to create synthetic control arms in upcoming clinical trials. This would grant an improved analysis of covariate relationships with the comparison of an investigational treatment to the standard of care osimertinib administered as first or second line. It would also reduce the number of patients needed in the trial.

Real-world clinical outcomes in a U.S. Asian population with stage IV NSCLC treated with osimertinib (Osi) stratified by EGFR subtype.

e21128 Background: EGFR mutations are observed in 40-50% of Asian populations with NSCLC compared to 10-15% in Caucasian populations, with EGFR exon 19 deletion (ex19del) and exon 21 L858R as the most common activating mutations. The FLAURA trial demonstrated PFS and OS benefit of osi, a 3rd generation tyrosine kinase inhibitor (TKI), compared to earlier generation TKIs with a median PFS (mPFS) of 19 months (mos) and overall survival (OS) of 38.6 mos. Subgroup analysis, however, suggested this survival benefit was not seen in Asian patients (pts) or in pts with the L858R mutation. Further analysis of the 322 Asian pts enrolled at Asian sites demonstrated a mPFS of 16.5 mos (HR 0.54, p < 0.0001) with osi compared to 11.0 mos with SOC EGFR TKI, but no difference on two-year OS (2y OS) (HR 0.65, 95% CI 0.42-1.02). We evaluated the 2y OS in Asian pts treated in the U.S. with stage IV NSCLC with first-line (1L) osi. We further explored the 2y OS of Asian pts who received an earlier generation EGFR TKI prior to osi. Methods: We conducted a single institution IRB-approved retrospective study of Asian pts treated at NYU Perlmutter Cancer Center with stage IV NSCLC with EGFR ex19del or L858R mutations treated with osi from 1/1/2010 – 2/1/2021. 2y OS was compared based on EGFR mutations and receipt of 1L osi vs an earlier generation EGFR TKI prior to osi (TKI-pretreated). Log-rank test was used to calculate the P values of Kaplan-Meier curves subgroups. Cox proportional-hazards model was used to investigate the association between the survival time of pts and multiple predictor variables including age, sex, EGFR subtypes (L858R or ex19del) and smoking status. Results: Of 117 total cases: 85 (73%) were female, 32 (36%) were male. 57 (49%) had ex19del and 60 (51%) had L858R. 94 (80%) were nonsmokers. Age range at diagnosis with stage IV disease was 31-96 years. The analysis revealed no significant difference in 2y OS observed between the 1L osi vs. TKI-pretreated groups (HR 1.90, 95%CI 0.93-3.89). However, the subgroup analysis showed that the 2y OS was inferior in the 1L osi group compared to the TKI-pretreated group in pts with ex19del (HR 2.99, 95%CI 1.12 -7.96), but not in those with L858R (HR 1.29, 95%CI 0.43-3.86). No significant effect on 2y OS was observed from age (p = 0.19), sex (p = 0.50), EGFR subtype (p = 0.19) or smoking status (p = 0.67). Conclusions: In accordance with the FLAURA data, our real-world analysis revealed that Asian pts treated with 1L osi was comparable to pts treated with 1st- or 2nd- generation TKIs. Furthermore, our data showed that the use of 1L osi had a lower 2y OS in Asian pts with ex19del compared to those pre-treated with TKIs, but this was not the case with L858R. Although small numbers, the results suggest that ex19del and L858R should be considered differently when considering 1L treatment options and further investigation into alternative options, such as combination therapies, warrants exploration.

Abstract 5675: Discovery and development of an asymmetric IgG-like bispecific antibody targeting EGFR and c-MET, engineered through H-H and H-L chain charge-based heterodimerization

Abstract Background: Lung cancer remains the leading cause of cancer mortality and is the most commonly diagnosed cancer with an estimated 2.2 million cases per year. EGFR, a tyrosine kinase receptor, plays a central role in cellular proliferation, survival, differentiation, and migration. Gain-of-function somatic mutations of EGFR significantly drives disease progression. Small molecule tyrosine kinase inhibitors (TKIs), designed to inhibit EGFR signaling specific to these mutations (e.g., L858R and E19del etc.), have achieved excellent clinical outcomes. However, patients carrying TKI-insensitive mutations (e.g., E20ins) and/or those with disease progression after TKI treatment, by the upregulation of complementary signaling pathways (HGF/c-MET, etc.), remain an unmet medical need. Here, we report the discovery of a fully-human afucosylated anti-EGFR x cMET IgG-like bispecific antibody (PM1080). Methods: PM1080 was generated by introducing unique mutations to the CH1-CL domains of each binding arm to promote correct HC-LC pairing. KIH mutations were also introduced to each CH3 domain to support HC-HC heterodimerization and generate an IgG-like bispecific with one arm binding to EGFR and the other to cMET. PM1080 was expressed via a four-chain expression system in CHO cells carrying a fut8−/− knockout to generate afucosylated molecules with enhanced ADCC activity. Results: Through monovalent affinity measurements, PM1080 interacted with EGFR at single digit nanomolar affinity and at sub-nanomolar affinity to c-MET. PM1080 preferentially bound to EGFR/c-MET double-positive cells rather than EGFR single-positive cells. PM1080 blocked both EGF/EGFR and HGF/c-MET signals via physical blockade of the interaction between EGF/HGF to their corresponding receptors and induced EGFR/c-MET internalization and degradation from the cell surface. Through intricate engineering, PM1080 was expressed via a four-chain system and produced as an afucosylated antibody with significantly improved ADCC function. PM1080 induced potent anti-tumor efficacy against EGFR/c-MET-positive tumor cells as a single agent. Importantly, PM1080 induced anti-tumor activity regardless of EGFR mutations at the intracellular signaling domain, and thus may serve as a promising combinational agent to TKI therapies. As expected, synergistic anti-tumor activity was observed when PM1080 was combined with either 1st or 3rd generation TKIs in both in vitro and in vivo models. Conclusion: PM1080, a bispecific antibody targeting EGFR & c-MET was discovered for cancer treatment. PM1080 displayed potent anti-tumor efficacy either as a single agent or in combination with EGFR TKIs. Preclinical PK and toxicity studies have been conducted to support future first-in-human studies. Citation Format: Ping Wang, Weifeng Huang, Zhenting Zhao, Xiaoniu Miao, Shaogang Peng, Chao Wang, Yao Yan, Tiantian Dong, Andy Tsun, Yingda Xu, Xiaolin Liu, Luo Yi. Discovery and development of an asymmetric IgG-like bispecific antibody targeting EGFR and c-MET, engineered through H-H and H-L chain charge-based heterodimerization. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5675.

Abstract 856: Comparison of the effect of two EGFR-TKI in patients with EGFR-mutant lung adenocarcinoma using in silico clinical trials

Abstract Introduction: 16,4% of lung adenocarcinomas (LUAD) are presenting a mutation in the Epidermal Growth Factor Receptor (EGFR), as reported in the Epidemiological Strategy and Medical Economics database[1], resulting in its constitutive activation and leading to uncontrolled cell proliferation. While some tyrosine kinase inhibitors (TKIs) have been developed to target EGFR mutations, their efficacy is not long-lasting, due to the emergence of resistance mutations[2]. Based on in silico approaches, we investigate and compare the impact of two TKIs (1st and 3rd generation) on tumor size evolution and clinical outcome, depending on the target population. Materials and Methods: We developed in Novadiscovery's jinkō platform a detailed mechanistic disease model of EGFR-mutant LUAD that predicts patients’ disease progression, based on their characteristics. We added on top of this disease model, a mechanistic physiologically-based pharmaco-kinetics model for each TKI drug, integrating their mechanisms of action. Publicly available data were used to calibrate the drug models and assess their credibility.We used the combination of the disease model with the two drug models to simulate clinical trials to compare the impact of both drugs on the course of the disease. Results:Both the 1st and 3rd generation TKI drug models can reproduce the pharmacokinetics in mice and humans. Combination of these models with the EGFR-mutant LUAD disease model is used to predict the tumor evolution in mice and the clinical outcome in humans. Differences in disease progression between treatments are observed according to the patients’ tumor mutational profiles. Discussion and Conclusion: The knowledge based construction of this EGFR mutant LUAD disease and treatment model successfully reproduced publicly available real-world data and will be challenged to reproduce the results from the FLAURA trial for an additional step of validation. The credibility of the model thereby acquired is a first step in the use of the model to compare existing treatments to investigational treatments and further support innovative therapies development. As such, in silico approaches are a complementary and valuable tool to existing in vitro or in animal experiments, alongside with clinical trials performance.

Cardiac toxicity of EGFR – 3rd generation TKI in patients with metastatic non-small cell lung cancer. Case report and literature data update

Purpose: The incidence of bronchopulmonary cancer has increased significantly in recent decades, especially in developed countries, and today it is the leading cause of death in men and the 3rd in women. The toxicities of tyrosine kinase inhibitor therapy are varied, with cardiac toxicities at the top of the pyramid. Because of the occurrence of these toxicities, depending on their intensity, the dose must be reduced or even treatment stopped. Patient and method: We present the case of a 72-year-old patient, diagnosed in 2019 with non-small bronchopulmonary neoplasm with histology of adenocarcinoma with EGFR mutation, stage IV. Results: In the oncology committee, it is decided to start targeted therapy with tyrosine kinase inhibitors of the first generation, Erlotinib, with a partial response to the treatment in the imaging evaluations, continued treatment until November 2020 when the T790M resistance mutation is detected. According to the new NCCN guidelines, therapy with the third-generation EGFR-TKI, Osimertinib, is initiated. In September 2021, the patient developed a non-ischemic acute antero-septal myocardial infarction that was complicated by LV apical aneurysm and severe LV systolic dysfunction, associated with therapy with tyrosine kinase inhibitors. Osimertinib treatment is stopped and third-line treatment with Vinorelbine is initiated. Conclusions: Investigation and permanent monitoring of patients, in treatment with 3rd generation tyrosine kinase inhibitors, who may develop cardiac toxicities, but also a good management of these toxicities, lead to both increased survival and improved status of performance.

Long Term Outcomes of Patients with Chronic Myeloid Leukemia Undergoing Allogeneic Hematopoietic Cell Transplantation in the Era of Oral Tyrosine Kinase Inhibitors

Introduction. Chronic Myeloid Leukemia (CML) is a myeloproliferative neoplasm (MPN) that without therapy is a uniformly lethal disease. Historically allogenic stem cell transplant (HCT) was the only curative therapy. In 2001 imatinib was the first CML specific oral tyrosine kinase inhibitor (TKI) approved and since then the treatment of CML has dramatically improved. Subsequently, 2nd and 3rd generation TKIs were developed and have been shown to be superior to imatinib either as initial therapy in certain high-risk patients and in other patients that fail imatinib. However, despite the advances in therapy, patients still die of CML, in fact, in 2020 it is estimated that 8,450 patients will be diagnosed with CML and 1,130 patients will die of CML. HCT remains a curative option for patients with CML. As the safety and availability of HCT improve, we aimed to describe the role of transplant in the modern era of CML therapy. Methods. We performed a retrospective chart review of patients who underwent their first HCT between June 28, 2006 and December 31, 2021 for CML in either chronic or accelerated phase at the time of transplant. Results. A total of 122 patients were identified. Patient and HCT characteristics are shown in Table 1. The median age at time of transplant was 45 (8-67), 72 (59%) are male. Fifty-four (44.3%) of patients received their transplant between 2006-2012 and 68 (55.7%) of patients received their transplants between 2013-2021. Fourteen (11.5%) patients were in accelerated phase CML at the time of HCT and the rest were in chronic phase. The median time from diagnosis to transplant was 23 months (1.8-307). Ninety-seven patients (79.5%) received ablative conditioning regimens. A total of 46 patients (37.7%) had matched related donors, 54 patients (44.3%) had matched unrelated donors, 14 patients (11.5%) had haploidentical donors, and 8 patients (6.7%) had a cord blood graft. 102 patients (83.6%) received peripheral blood stem cell grafts. GVHD prophylaxis always included a calcineurin inhibitor with the addition of methotrexate in 36 (29.5%) of patients, sirolimus in 60 (49.2%), Mycophenolate in 7 (5.7%), and post-transplant cyclophosphamide in 19 (15.6%) patients. Sixty-one patients (50%) had grade 2 or higher acute GVHD, and 19 (15.6%) had grade 3-4 acute GVHD. Extensive chronic GVHD was present in 81 (66.4%) of patients. Median follow-up of surviving patients was 59.3 months (3.3, 183.8) and overall the median follow-up was 30 months (0.55, 183.8). The estimated 12, 36, and 60-month Overall Survival (OS) of the cohort was 76.9% (95%CI 69.7-85), 66.1% (95% CI 57.7-75.6), and 58.4% (95% CI 49.4-69). Progression free survival (PFS) of the cohort at 12, 36, and 60 months was 71% (95% CI 63.2-79.7), 62% (95% CI 53.6-71.7) and 54.1% (45.1-65%) respectively. The median OS and PFS was not reached (Figure 1a,b). Fifty-two patients in the cohort died, 31 (59.6%) died of complications of treatment, 12 (23.1%) died of progression of disease, and 9 (17.3%) died of unknown causes. The day 100 cumulative incidence of non-relapse mortality (NRM) was 4.1% (1.7-9.7%) and the 1-year NRM was 17.2% (11.5-25.7%). Conclusion. This study shows excellent long term survival in patients who received an allo HCT for CML. And while, the modern treatment of CML largely relies on oral TKIs, in those patients who do not tolerate TKIs or fail available TKIs, allogeneic transplant remains an active, potentially curable therapy and should be considered. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Therapy in Patients with Chronic Myeloid Leukemia Outside of Clinical Trials: Results of the German CML-Registry (CML-VI)

Introduction: Tyrosine kinase inhibitors (TKI) have significantly improved treatment outcomes for patients with newly diagnosed chronic myelogenous leukemia (CML) in chronic phase (CP). With the introduction of 2nd and 3rd generation TKI, the options in the management of CML have increased. In clinical trials, 25%-50% of patients do not remain on initial treatment due to intolerance or inefficacy. Information outside of clinical trials is limited. Aim: The aim of this study is to analyze the use of different TKI in first-line treatment and the frequency of TKI switches in CML in real world. Methods: Patients with newly diagnosed CML between 1.1.2013 and 31.12.2019 were registered and followed annually up to 31.12.2021. Primary endpoint was the time to and reason for switching of any first-line treatment including treatment free remission (TFR)attempt. Further endpoints were progression-free survival (PFS), overall survival (OS), cytogenetic and molecular response. Analyses were performed using Kaplan-Meier estimates with SPSS. Results: 540 adult patients have been registered from 91 centers, 512 were evaluable. 281 patients (55%), were treated by resident oncologists, 231 patients (45%) in hospitals including 82 patients (16%) in university hospitals. 271 patients (53%) were male. At diagnosis, median age was 59 (range 16-100) years. The median follow-up was 67 (3-108) months. Information on first-line TKI treatment was available for 480 patients: 203 patients (42%) were treated with imatinib, 137 (29%) with nilotinib and 140 (29%) with dasatinib. TKI switch was reported in 155 cases (31%) after a median of 11 (0-68) months. Reasons for switching was failure in 49 patients (32%), intolerance in 88 patients (57%), and 18 patients (11%) switched TKI because of other reasons (study inclusion, desire to have children, patient request, unknown). 33 patients (7%) switched TKI more than once. 13 (8,4%) of the 155 patients with TKI-switch died during follow-up, whereas only 16 of 325 (4,9%) patients without TKI-switch. OS of patients with TKI-switch was 90%, of patients without TKI-switch 94% after 6 years. TKI stop for more than one month has been reported in 118 patients (24%) due to different reasons (attempt for TFR, intolerance, patient wish, pregnancy). 61 patients (12%) started a TFR attempt after a median of 46 (10-96) months of TKI treatment. Discontinuation criteria were not always met. Only 10 patients (6,5%) with TKI-switch started a TFR attempt compared to 51 patients (16%) who had only been treated with one TKI. 501 patients were in CP at diagnosis, 11 patients in accelerated phase (AP) and 2 patients in blast crisis (BC). Progression occurred in 9 patients (BC n=6, AP n=3) after a median time of 12 (9-22) months. Overall, AP and BC were diagnosed in 22 patients (2,3%). Of the total cohort, 29 patients died, OS was 93% after 6 years. An evaluable cytogenetic examination was carried out in 291 patients (57%) at diagnosis or in the course of disease. No statements can be made about achieving of complete cytogenetic remission as follow up results were only available in 15% and monitoring was carried out using RQ-PCR in most patients. A major molecular response (MMR, BCR::ABL1 <0.1%) was reached by 422 patients (85%), a deep molecular response (defined as BCR::ABL1 ≤0.01) by 365 patients (74%) within the follow-up period. Cumulative incidence calculation and study of patients who lost their MMR are ongoing. There is no information about the molecular status of 18 patients. Conclusion: Results of the CML VI-registry provided information on treatment but also on baseline characteristics and diagnostic parameters of CML patients in real world. The median age of the patients at diagnosis was higher than in other clinical trials. In routine care, data demonstrated high switching rates of first-line treatment and frequent TFR attempts without meeting the guideline criteria. OS rates were as high as in clinical trials and confirm normal life expectation of CML patients. MMR was reached in 85% and DMR in 74% in this population. Progression is rare. In conclusion, the CML-registry offers importing data confirming a good outcome of response and survival for CML patients outside of clinical trials. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Frontline Combination of Hyper-CVAD with Ponatinib for Patients with Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia-6-Year Follow-up Results

Background: The combination of cytotoxic chemotherapy with a BCR::ABL1 tyrosine kinase inhibitor (TKI) has historically been standard of care for patients (pts) with Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL). Ponatinib is 3rd generation TKI with more potent BCR::ABL1 inhibition than earlier-generation TKIs. Ponatinib also suppresses T315I clones, which are responsible for most relapses with other TKIs. Here we present the 6-year follow-up results of hyper-CVAD plus ponatinib for patients with newly diagnosed Ph+ ALL. Methods: This was a phase 2, single-arm study to evaluate the efficacy and safety of hyper-CVAD with ponatinib in adults with newly diagnosed Ph+ ALL. Pts age 18 years or older with previously untreated Ph+ ALL were eligible; pts who had received 1 to 2 courses of prior chemotherapy, with or without a TKI, were also eligible. Pts were required to have an ECOG performance status of 2 or less, bilirubin <3mg/dl, creatinine <3mg/dl, and normal cardiac function. Pts received hyper-CVAD alternating with high-dose methotrexate and cytarabine for 8 cycles. Initially, ponatinib was given at a dose of 45 mg daily. Due to 2 deaths due to cardiovascular events related to ponatinib, beginning with pt #37, the protocol was amended. After the amendment, ponatinib was administered at a dose of 45 mg for 14 days in cycle 1, then 30mg daily once patients achieved CR and 15mg daily once a complete molecular response (CMR) was achieved. Maintenance therapy was given for 2 years, vincristine, prednisone and ponatinib. Pts received 12 doses of intrathecal chemotherapy with alternating doses of cytarabine and methotrexate. Results: 86 pts were treated. Pts characteristics are summarized in Table 1. The median age was 46 years (range 21-80). Sixty-six pts (77%) had received no prior ALL-directed therapy, and 20 pts (23%) had received 1-2 courses of therapy prior to enrollment. Among these 20 pts, 18 were in CR and 2 had persistent disease at the time of enrollment. Sixty three pts (73%) had a p190 transcript, and 21 (24%) had a p210 transcript. Among 68 pts with active disease at enrollment, all pts achieved CR. Among 54 pts evaluable for cytogenetic response, all pts achieved complete cytogenetic response, including 50 pts (93%) after 1 cycle. Among 85 pts evaluable for molecular response, 83 pts (98%) achieved at least a major molecular response and 73 pts (86%) achieved a CMR. No pts died in the first 4 weeks of therapy. After a median follow up of 75 months (range, 16-123+ months), the 5-year overall survival (OS) and relapse-free survival rates were 75% and 68%, respectively (Figure 1). Twenty pts (23%) underwent stem cell transplantation (SCT) in first remission (5 of whom relapsed post SCT and 1 of whom died from post-SCT complications), 10 pts (12%) died in CR, 13 pts (19%) relapsed without SCT, and 43 pts (50%) are in ongoing remission without SCT. Of the relapsed pts, 5 were on ponatinib at the time of relapse, 2 of whom acquired an E255K kinase domain mutation at relapse; and 5 were on imatinib or dasatinib at the time of relapse, 3 of whom acquired a T315I kinase domain mutation. Among the 10 deaths in CR, 2 were treatment-related (both due to myocardial infarction before the amendment to implement lower doses of ponatinib). In a 8-month landmark analysis, the 5-year OS for pts without ASCT and with ASCT were 87% and 70%, respectively (p =0.09). Among the pts who are in ongoing remission without ASCT, 3 received subsequent therapy for MRD-positive disease. The most common grade ≥3 AE was infections and/or febrile neutropenia, seen in 82 pts (95%). Other grade ≥3 AEs including elevated transaminases in 25 pts (29%), increased amylase and/or lipase in 15 (17%), hyperbilirubinemia in 13 pts (15%), and clinical pancreatitis in 13 pts (15%). Five pts (6%) had a grade ≥3 venous thrombotic event, and 5 pts (6%) had a grade ≥3 arterial cardiovascular event. Two patients died from ponatinib-related cardiovascular complications, both from MI during cycle 2. Conclusion: The combination of hyper-CVAD and ponatinib results deep and durable remissions in pts with newly diagnosed Ph+ ALL. The overall CMR rate was 86% and the 5-year OS was 75%, which compares favorably with regimens using first- or second-generation TKIs in this population. The combination was safe; the use of lower doses of ponatinib maintained efficacy and mitigated the risk of ponatinib-related toxicity. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Allogeneic Blood or Marrow Transplantation (AlloBMT) with High-Dose Post-Transplantation Cyclophosphamide (PTCy) for Acute Lymphoblastic Leukemia (ALL) in Patients Aged ≥ 55: Best Results in B ALL in First Remission (CR1) with Reduced-Intensity Conditioning (RIC)

Background: Older patients with ALL fare poorly with conventional chemotherapy. Patients aged 55-65 on E2993 and ≥ 60 treated with Hyper-CVAD have 5-year overall survival (OS) of just 21% and 20%, respectively (Sive. BJH. 2012 and O'Brien. Cancer. 2008). Recently, HyperCVD with inotuzumab +/- blinatumomab in patients ≥ 60 years old with Ph- B ALL demonstrated an improved 5-year OS of 47% with 38% of patients dying in remission (Short. Blood. 2021). AlloBMT provides an alternative consolidation strategy. Registry studies in ALL patients ≥ 60 years old and B ALL patients ≥ 55 years old who underwent alloBMT with RIC in CR1 demonstrated 5 and 3-year OS of 42% and 45%, respectively (Roth-Guepin. Oncotarget. 2017 and Rosko. Am J Hematol. 2017). These studies utilized heterogenous conditioning and graft-versus-host disease (GVHD) prophylaxis regimens. The use of high-dose post-transplantation cyclophosphamide as GVHD prophylaxis facilitates transplants in older adults with low rates of non-relapse mortality, GVHD, and the use of HLA haploidentical donors (Kasamon. JCO. 2015). Methods: The bone marrow transplant database at Johns Hopkins was queried for patients ≥ 55 years old who received a first alloBMT using PTCy from January 2008-January 2021. Characteristics of patients were summarized and compared using Fisher's exact test for categorical variables. Estimators of OS and relapse-free survival (RFS) were reported using the Kaplan-Meier method. Differences in time-to-event outcomes were estimated using Cox proportional hazards model, or Fine and Gray's model for cumulative incidence of relapse (CIR)/nonrelapse mortality (NRM) considering competing risks. Results: A total of 77 patients aged ≥ 55 underwent a first alloBMT with PTCy for ALL. The vast majority were performed in CR1 (85.7%), utilized RIC (88.3%), and were performed for B ALL (90.9%). Demographics and transplant characteristics are presented in Table 1. RIC consisted of fludarabine, cyclophosphamide and total body irradiation followed by PTCy-based GVHD prophylaxis as previously described (Kasamon. BBMT. 2008). Relapse-free survival (RFS) and OS at 5 years for the entire cohort were 46% (95% CI 34-57) and 49% (95% CI 37-60), respectively, with a 5-year CIR of 27% (95% CI 18-38) and NRM of 28% (95% CI 18-39). The cumulative incidences of grade 3-4 acute GVHD at 1 year and chronic GVHD at 3 years were 3% (95% CI, 0% to 9%) and 13% (95% CI 5% to 21%), respectively. In univariate analysis, the use of myeloablative conditioning led to worse RFS (HR 0.25, p=0.0004); while the absence of MRD (HR 2.93, p=0.008), transplant in CR1 (HR 3.81, p=0.0004), and transplant for Ph+ ALL vs. T ALL (HR 3.15, p=0.03) led to improved RFS. Subsequent analysis focusing on the 54 patients receiving RIC alloBMT in CR1 for B ALL demonstrated RFS and OS at 5 years of 61% (95% CI 46-73) and 64% (95% CI 49-76), respectively, (see Figure 1) with a 5-year CIR of 16% (95% CI 7-27) and NRM 24% (95% CI 13-36), although just 7% at 1 year. For B ALL patients transplanted with RIC in CR1, 3-year NRM was higher among patients who received a peripheral blood stem cell transplant (55%, 95% CI 18% to 81%), those treated with rituximab pre-transplant (36%, 95% CI 16% to 57%), and those who received ≥100 mg/m2 of doxorubicin equivalent for ALL (67%, 95% CI 19% to 90%). Outcomes did not differ among the 20% of patients who received pre-transplant blinatumomab compared to those who did not. Among the 23 Ph+ B ALL patients transplanted with RIC in CR1 following treatment with a 2nd or 3rd generation tyrosine kinase inhibitor (TKI), the 5-year CIR was 5% (95% CI, 0% to 22%). Conclusions: RIC AlloBMT with PTCy in CR1 represents a promising consolidation strategy for B ALL patients ≥ 55 years old. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

The First Report of Third-Generation TKI Olverembatinib in Adult Ph/BCR-ABL1-Positive Acute Lymphoblastic Leukemia with T315I Mutation and Relapsed Disease

Background Tyrosine kinase inhibitors (TKIs) have significantly improved the prognosis of patients(pts) with Ph/BCR-ABL1-positive (Ph/BCR-ABL1+) acute lymphoblastic leukemia (ALL). However, mutations in the ABL1 kinase domain, especially T315I, are the main mechanism of resistance to the first- or second-generation TKIs. Olverembatinib is a novel third-generation TKI developed in China and approved in Dec. 2021, which has been demonstrated great efficacy and safety in clinical trials of CML with T315I mutation. Our study is the first application of Olverembatinib in adult Ph/BCR-ABL1+ ALL with T315I mutation. Herein, we report the preliminary results. Methods In this exploratory study, adult Ph/BCR-ABL1+ ALL pts with T315I mutation or disease progression were treated with olverembatinib monotherapy (40 mg, every 2 days) or in combination with VP based low intensive chemotherapy (Vincristine/Prednisone) in our institution. Efficacy was assessed by complete remission (CR) rate, MRDneg (<0.01%) rate by multiparameter flow cytometry (MFC) and CMR (BCR-ABL1 transcript<10-5) rate by real-time quantitative polymerase chain reaction (RT-qPCR). Safety profiles were also monitored in this study. Results From December 2021 to June 2022, 10 Ph/BCR-ABL1+ ALL pts were treated with olverembatinib due to T315I mutation or disease recurrence, after prior TKIs combined with chemotherapy. Median age was 60.5 years (range, 37-65), and 6/10 were males. 5 pts had received 2 types of TKIs previously, of which 2 pts relapsed after ponatinib (Table 1). Among 10 pts, 6 were still in CR1 (pt 1-6), their T315I mutations were detected during regular follow-up. 4/6 pts were persistently molecular positive, while the other 2 had molecular relapse. Median time from diagnosis to the administration of olverembatinib was 5 months (range, 3-17). Among the 4 pts with hematologic relapse (pt 7-10), 2 (pt 7, 8) had T315I mutation. Because of the successive occurrence of G250E, Y253H, L248V mutations and L248 K274del, the 3rd one (pt 9) relapsed twice and failed to response to two kinds of TKIs and chemotherapy. As for the last pt (pt 10), although no ABL1 mutations were found, she was in 3rd relapse with CNS and BM involvement. Median time from diagnosis to the start of olverembatinib for these 4 relapsed pts was 28 months (range, 5-41). Among 6 pts with T315I mutation and persistent molecular diseases or molecular relapse, the CMR rate was 66.7%, with a median time of 3 months (range, 1-4) to achieve CMR. Then 2 pts underwent allo-HSCT (pt3, 4), who were still in CR. Among 4 hematological relapsed pts, the CR rate was 75%. 1 pt (pt8) with T315I was unresponsive, while another T315I positive patient achieved MRDneg by MFC after 1 month of treatment, with a complete disappearance of T315I mutation (pt7), though the BCR-ABL1 transcript was still positive. The remaining 2 relapsed pts without T315I mutation achieved hematologic CR after 1 month of olverembatinib monotherapy (pt9,10). Totally, overall response rate (ORR) was 70% and MRDneg rate by MFC was 71.4% (5/7), while the CMR rate by PCR was 57.1% (4/7). Notably, olverembatinib was ineffective in neither of the 2 pts who have been previously treated by ponatinib. Meanwhile, the olverembatinib-based therapy was well-tolerated, and the main adverse events of the third-generation TKIs, such as cytopenia, elevated transaminases, hypertension, and cardiovascular events, were less frequent than those reported relating to ponatinib. In addition, 4 patients developed grade 1 skin pigmentation (pt2,3,6,9). There were no drug-related death or permanent discontinuation due to toxicity. Conclusion This work suggests that Olverembatinib is a very promising 3rd-generation TKI. It is effective and safe in Chinese adult Ph/BCR-ABL1+ ALL with extremely poor prognosis, especially in T315I mutated or relapsed pts. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

398TiP MARIPOSA-2: Randomized phase III study of amivantamab + lazertinib + chemotherapy vs chemotherapy alone in EGFR-mutant NSCLC after osimertinib failure

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) effectively treat patients with non-small cell lung cancer (NSCLC) with EGFR-sensitizing mutations; however, almost all will eventually relapse due to new mutations on or after osimertinib the 3rd generation TKI. The current standard of care is platinum doublet chemotherapy after progression on osimertinib, but with limited benefit. Amivantamab, an EGFR and MET bispecific humanized antibody, has shown clinical activity against tumors with primary activating EGFR mutations, EGFR resistance mutations, or MET pathway activation.

64 (PB054) - BDTX-1535, a fourth generation EGFR inhibitor, targeting intrinsic and acquired resistance mutations in NSCLC

Background: The classical mutations of the epidermal growth factor receptor (EGFR) in NSCLC are the exon 19 del and exon 21 (L858R) mutations. The 3rd generation EGFR tyrosine kinase inhibitor (TKI), osimertinib, has become the first-line treatment of choice for NSCLC patients with these mutations. Resistance to 3rd generation TKIs can be driven by gain of secondary EGFR alterations, e.g., substitution at cysteine-797 to serine (C797S). Real world evidence shows that in addition to C797S, other EGFR alterations are also acquired upon osimertinib treatment, including kinase domain mutations (e.g., S768I), extracellular domain alterations (e.g., EGFRvIII, A289X), and EGFR amplification. In addition to the classical mutations, NSCLC tumors express a wide spectrum of primary kinase domain mutations including G719X in exon 18, S768I in exon 20, and L861Q in exon 21, which confer intrinsic resistance to approved TKIs. NCCN guidelines recommend the use of afatinib or osimertinib, however, there remains a need for an EGFR TKI that targets these mutations with high potency, good tolerability, and CNS penetration. Our MAP platform allowed us to select MasterKey inhibitor BDTX-1535, a 4th-generation CNS penetrant EGFR TKI, that potently and selectively targets multiple intrinsic and acquired resistance EGFR alterations. Materials and Methods: BDTX-1535 preclinical exposure was evaluated across species, and PK and Kpuu values were calculated in brain and plasma. Antitumor activity was assessed across a broad range of mouse PDX and allograft models. Results: BDTX-1535 is a potent and selective, CNS penetrant, wild type sparing, irreversible EGFR TKI targeting Exon 18–21 alterations which are associated with intrinsic or acquired resistance to 3rd generation EGFR inhibitors. These include a broad range of kinase domain EGFR mutations (e.g., C797S, L718Q, G724S, S768I), extracellular domain alterations (e.g., EGFRvIII, A289X), and EGFR amplification. Mouse xenograft and allograft studies showed that BDTX-1535 consistently achieves regression of tumors carrying these mutations at well tolerated doses without significant EGFR wild type associated toxicities. BDTX-1535 is orally bioavailable with a CNS Kpuu of 0.55 and 0.48 in rat and dog, respectively, and active in an intracranial PDX model. Conclusions: BDTX-1535 is a 4th generation CNS penetrant EGFR TKI discovered using the MAP platform which allows MasterKey targeting of EGFR alterations associated with intrinsic or acquired resistance to 3rd generation EGFR TKIs, while sparing wild type EGFR. This broad spectrum coverage of resistance mutations in conjunction with CNS penetration properties allows BDTX-1535 to address a key unmet medical need in EGFR mutant lung cancer. BDTX-1535 is currently under phase I clinical investigation (NCT05256290). Conflict of interest: Ownership: Black Diamond Therapeutics

999P JIN-A02, a fourth-generation, highly effective tyrosine kinase inhibitor with intracranial activity, targeting EGFR C797S mutations in NSCLC

Even though epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI) have improved treatment outcomes for EGFR-driven NSCLC, resistance inevitably emerges and disease often progresses due to brain metastasis. The C797S is the most significant resistance mutation to occur after 3rd generation TKIs treatment. JIN-A02 is an orally available EGFR-TKI targeting C797S mutation with high brain penetration. Cellular activities of JIN-A02 were evaluated on phosphorylation-EGFR expression with AlphaLISA assay and on EGFR mutants with patients-derived cell (PDC) and patients-derived organoid (PDO). Different type of allelic relationship was also assessed in all models by whole exome sequencing. Patients-derived xenografts (PDX) was used to assess antitumor activities of JIN-A02. For in vivo intracranial activity, NCI-H1975 cell line derived tumor xenograft was used. In AlphaLISA assay, JIN-A02 showed high potency in EGFRex19del/T790M/C797S (IC50=4.7 nM, Ba/F3), EGFRL858R/T790M/C797S (IC50=12.8 nM, NCI-H1975 LTC). JIN-A02 strongly inhibited cellular activity of in trans model (IC50=89.7 nM, PDO) and in cis model (IC50=92.1 nM, PDC) of EGFRex19del/T790M/C797S. It appears to be superior to osimertinib (IC50 >4,000 nM for both cells). In addition, JIN-A02 showed comparable potency to osimertinib in EGFRex19del/T790M (IC50=84.4 nM for PC-9GR), and EGFRL858R/T790M (IC50=73.3 nM for NCI-H1975). In the PDX mouse model (YHIM-1094, EGFRex19del/T790M/C797S), JIN-A02 delayed tumor growth at a dose of 30 mg/kg. In the brain metastases model, antitumor activity of JIN-A02 was observed with intracranial implanted NCI-H1975 tumors. JIN-A02 is highly potent EGFR-TKI for various EGFR targeted mutations including in cis and trans EGFRex19del/T790M/C797S and shows intracranial activity. Based on these robust activities for EGFR mutants, JIN-A02 is expected to provide a potential therapeutic opportunity for NSCLC.