Tyrosine Kinase Inhibitors Treatment Research Articles

A Path to Persistence after EGFR Inhibition.

Residual cancer cells persist even after targeted therapies, serving as a reservoir for the subsequent acquisition of genetic alterations that lead to acquired drug resistance and tumor relapse. These initial drug-tolerant persisters (DTP) are phenotypically heterogenous with transient phenotypes attributed to epigenetic, metabolic, and cell-cycle changes. DTPs are responsible for the inevitable relapse seen in EGFR-mutant non-small cell lung cancer (NSCLC) despite high initial response to tyrosine kinase inhibitor (TKI) treatment. While past in vitro studies identified diverse drivers of drug-tolerant persistence to EGFR TKIs in NSCLC, the resultant phenotypic plasticity is not well understood and in vivo models of persistence are lacking. In this issue of Cancer Research, Hu and colleagues used patient-derived xenograft models of EGFR-mutant lung cancer treated with the third-generation TKI osimertinib to investigate mechanisms of persistence at the time of maximal response. Using bulk and single-cell RNA sequencing, the authors identified a DTP transcriptional cluster mediated by the key neuroendocrine lineage transcription factor ASCL1, which triggers an epithelial-to-mesenchymal transition transcriptional program. ASCL1 overexpression increased osimertinib tolerance in vitro as well, apparently independent of its role in neuroendocrine differentiation. Interestingly, the ability of ASCL1 to induce persistence was context dependent as this occurred only in epigenetically permissive cells. Overall, these findings contribute to our understanding of DTP heterogeneity seen after osimertinib treatment and provide insights into potential therapeutic targets. See related article by Hu et al., p. 1303.

Richter transformation acquiring PLCG2 mutation during Bruton tyrosine kinase inhibitors treatment

Richter transformation acquiring <i>PLCG2</i> mutation during Bruton tyrosine kinase inhibitors treatment

Induction of the Inflammasome Pathway by Tyrosine Kinase Inhibitors Provides an Actionable Therapeutic Target for Hepatocellular Carcinoma

During the last decade, tyrosine kinase inhibitors (TKIs) sorafenib and regorafenib have been standard systemic treatments for advanced hepatocellular carcinoma (HCC). Previous data associated sorafenib with inflammasome activation. However, the role of the inflammasome in sorafenib and regorafenib signaling has not been described in liver cancer patients. For this purpose, we analyzed inflammasome-related transcriptomic changes in a murine HCC model. Our data confirmed inflammasome activation after both TKI treatments, sharing a similar pattern of increased gene expression. According to human database results, transcriptional increase of inflammasome genes is associated with poorer prognosis for male liver cancer patients, suggesting a sex-dependent role for inflammasome activation in HCC therapy. In biopsies of HCC and its surrounding tissue, we detected durable increases in the inflammasome activation pattern after sorafenib or regorafenib treatment in male patients. Further supporting its involvement in sorafenib action, inflammasome inhibition (MCC950) enhanced sorafenib anticancer activity in experimental HCC models, while no direct in vitro effect was observed in HCC cell lines. Moreover, activated human THP-1 macrophages released IL-1β after sorafenib administration, while 3D Hep3B spheres displayed increased tumor growth after IL-1β addition, pointing to the liver microenvironment as a key player in inflammasome action. In summary, our results unveil the inflammasome pathway as an actionable target in sorafenib or regorafenib therapy and associate an inflammasome signature in HCC and surrounding tissue with TKI administration. Therefore, targeting inflammasome activation, principally in male patients, could help to overcome sorafenib or regorafenib resistance and enhance the efficacy of TKI treatments in HCC.

Oxidative Stress and Chronic Myeloid Leukemia: A Balance between ROS-Mediated Pro- and Anti-Apoptotic Effects of Tyrosine Kinase Inhibitors

The balanced reciprocal translocation t (9; 22) (q34; q11) and the BCR-ABL fusion gene, which produce p210 bcr-abl protein production with high tyrosine kinase activity, are characteristics of chronic myeloid leukemia, a myeloproliferative neoplasm. This aberrant protein affects several signaling pathways connected to both apoptosis and cell proliferation. It has been demonstrated that tyrosine kinase inhibitor treatment in chronic myeloid leukemia acts by inducing oxidative stress and, depending on its level, can activate signaling pathways responsible for either apoptosis or survival in leukemic cells. Additionally, oxidative stress and reactive oxygen species generation also mediate apoptosis through genomic activation. Furthermore, it was shown that oxidative stress has a role in both BCR-ABL-independent and BCR-ABL-dependent resistance pathways to tyrosine kinases, while patients with chronic myeloid leukemia were found to have a significantly reduced antioxidant level. The ideal environment for tyrosine kinase inhibitor therapy is produced by a favorable oxidative status. We discuss the latest studies that aim to manipulate the redox system to alter the apoptosis of cancerous cells.

Financial difficulties experienced by patients with gastrointestinal stromal tumours (GIST) in the Netherlands: data from a cross-sectional multicentre study

PurposeThis study aims to (1) explore the prevalence of patient-reported financial difficulties among GIST patients, differentiating between those currently undergoing tyrosine kinase inhibitor (TKI) treatment and those who are not; (2) investigate associations between financial difficulties and sociodemographic and clinical characteristics, work, cancer-related concerns, anxiety and depression and (3) study the impact of financial difficulties on health-related quality of life.MethodsA cross-sectional study was conducted among Dutch GIST patients diagnosed between 2008 and 2018, who were invited to complete a one-time survey between September 2020 and June 2021. Patients completed nine items of the EORTC item bank regarding financial difficulties, seven work-related questions, the Hospital Anxiety and Depression Scale, Cancer Worry Scale and EORTC QLQ-C30.ResultsIn total, 328 GIST patients participated (response rate 63.0%), of which 110 (33.8%) were on TKI treatment. Patients currently treated with TKIs reported significantly more financial difficulties compared to patients not on TKIs (17.3% vs 8.7%, p = 0.03). The odds of experiencing financial difficulties was 18.9 (95% CI 1.7–214.7, p = 0.02) times higher in patients who were less able to work due to their GIST diagnosis. Patients who experienced financial difficulties had significantly lower global quality of life and functioning, and more frequently reported psychological symptoms as compared to patients who did not report financial difficulties.ConclusionEven in a country where the costs of TKIs and follow-up care are covered by health insurance, financial difficulties can be present in GIST patients, especially in patients on TKI treatment, and may negatively influence the quality of life.

Abstract LB182: Mutagenesis screens support potential best-in-class profile for selective, brain-penetrant, and TRK-sparing ROS1 inhibitor NVL-520

Abstract Introduction. ROS1 fusions are recurrent oncogenic drivers in non-small cell lung cancer (NSCLC). Tyrosine kinase inhibitors (TKIs) crizotinib, entrectinib, and repotrectinib have been approved for the treatment of ROS1-positive NSCLC. Response to these TKIs can be limited by emergence of drug resistance, with ~40% of patients acquiring on-target ROS1 mutations at progression on crizotinib. NVL-520 is an investigational, brain-penetrant, and TRK-sparing ROS1 TKI designed to maintain activity for ROS1 mutations that confer resistance to approved therapies. To investigate suppression of resistance by NVL-520, we performed two N-ethyl-N-nitrosourea (ENU) mutagenesis screens and determined the frequency and identity of resistance mutations following treatment with NVL-520 versus earlier-generation ROS1 TKIs. Methods. Cells were treated with ENU for 1 day followed by crizotinib, entrectinib, repotrectinib, or NVL-520 for 28 days. Frequency of resistance indicates the fraction of wells that proliferated on day 28 despite continuous TKI treatment. Resistance mutations in the ROS1 kinase domain were identified by Sanger sequencing. Resistant clones harboring ROS1 kinase-domain mutations were expanded and used to profile the inhibitory activity of ROS1 TKIs. Results. The first ENU screen was performed on Ba/F3 CD74-ROS1, simulating a first-line treatment setting. NVL-520 at an unbound drug concentration (Cunbound) of 8.2 nM yielded 1 resistant clone among 480 replicate wells (frequency of resistance = 0.2%). The second screen was performed on Ba/F3 CD74-ROS1 G2032R, which is the most common point mutation after progression on previous-generation therapies, simulating a later-line treatment setting. NVL-520 at Cunbound of 41 nM yielded 6 resistant clones among 480 replicate wells (frequency of resistance = 1.3%). These NVL-520 concentrations (8.2 - 41 nM) were well within its average Cunbound of 166 nM at the recommended phase 2 dose (RP2D) of 100 mg once daily. None of the 7 resistant clones harbored ROS1 kinase-domain mutations, suggesting an off-target resistance mechanism. Crizotinib, entrectinib, and repotrectinib at their respective average human Cunbound yielded frequencies of resistance ranging from &amp;gt;33% to 100% in at least one of the screens, indicating that they were less effective than NVL-520 at suppressing resistance in these screens. Conclusion. NVL-520 was highly effective at suppressing resistance in ENU mutagenesis screens simulating first-line (CD74-ROS1) and later-line (CD74-ROS1 G2032R) treatment. The screens did not reveal any novel ROS1 mutations that could confer resistance to NVL-520 at the RP2D. The broad preclinical activity against ROS1 and diverse ROS1 mutations, together with its brain penetrance and TRK-sparing design, suggests NVL-520 as a potential best-in-class ROS1 therapy. Citation Format: Anupong Tangpeerachaikul, Franklin Gu, Henry E. Pelish. Mutagenesis screens support potential best-in-class profile for selective, brain-penetrant, and TRK-sparing ROS1 inhibitor NVL-520 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB182.

Endothelial function in patients with chronic myeloid leukemia treated with tyrosine kinase inhibitors is not related to cardiovascular risk assessed by SCORE2 algorithm.

Tyrosine kinase inhibitors (TKIs) revolutionized the treatment of chronic myeloid leukemia (CML) but are endowed with negative effects on endothelial function. To characterize endothelial function in patients with CML treated with various TKIs. Forty-eight patients diagnosed with chronic phase CML treated with TKIs, such as imatinib, bosutinib, nilotinib, ponatinib, and asciminib were included. Endothelial function was assessed in the brachial artery and microcirculation based on flow-mediated dilation (FMD), reactive hyperemia peripheral arterial tonometry (RH-PAT) and Flow Mediated Skin Fluorescence (FMSF). Reactive Hyperemia Index (RHI), FMD [%], Reactive Hyperemia Response (RHR [%]), Normoxia Oscillatory index (NOI [%]) and Hyperemic Response index (HR index [%]) did not differentiate between the group of patients with low / moderate risk in the Systemic Coronary Risk Estimation 2 (SCORE2), SCORE2-Older Persons (SCORE2-OP) and those with high / very high-risk scores. Among patients with low/intermediate risk based on the SCORE2 algorithms, some had lower (<Q1) values of endothelial parameters, reflecting impaired endothelial function, when compared with the whole population. Lower values of endothelial function parameters were associated with overall long-term treatment with TKIs or ponatinib treatment. Importantly, endothelial function assessed by FMSF (RHR [%]) negatively correlated with the total duration of TKI treatment, also after adjustment for age. Endothelial function in CML patients treated with TKIs was not related to cardiovascular risk based on SCORE2/SCORE2-OP algorithms but CML-specific factors, including duration of TKI treatment. FMSF-based assessment of skin microcirculation was a sensitive method for detecting the vascular effects of TKIs.

Clinical Characteristics and Outcomes of TFE3-Rearranged/TFEB-Altered Renal Cell Carcinoma with Systemic Therapies, Including Tyrosine Kinase Inhibitors or Immune Checkpoint Inhibitors: An Observational Study

Purpose: &lt;i&gt;TFE3&lt;/i&gt;-rearranged/&lt;i&gt;TFEB&lt;/i&gt;-altered renal cell carcinoma (RCC) is a rare subtype of RCC. Due to its rarity, there is an unmet medical need for effective therapies in advanced settings. The study aims to investigate the clinical and histopathological characteristics of patients with microphthalmia transcription factor family/ transcription factor E (MiTF/TFE) translocation RCC and the clinical outcomes of systemic therapies, including tyrosine kinase inhibitors (TKIs) or immune checkpoint inhibitors (ICIs).Materials and Methods: This was a single-center, retrospective study. We identified 32 eligible patients among a total of 37 patients diagnosed with MiTF/TFE translocation RCC between January 2004 and September 2021, and the study included 9 patients who were treated with systemic therapies. We collected data on clinical characteristics, targeted sequencing, and clinical outcomes.Results: The median age of the 32 patients was 45.5 years. Histologically, 26 patients (81.3%) had &lt;i&gt;TFE3&lt;/i&gt;-rearranged RCC, and only 1 patient (3.1%) had &lt;i&gt;TFEB&lt;/i&gt;-altered RCC. Curative or cytoreductive nephrectomy was performed in all 27 patients (84.4%), and 4 patients (12.6%) were diagnosed with metastatic disease at the time of the initial diagnosis. Nine patients (28.1%) were treated with systemic therapy with TKIs, 2 (6.3%) of whom received simultaneous TKI and ICI treatment. The response to systemic therapy (TKI or ICI) and duration of response ranged from complete response to progressive disease. Excluding 1 patient who was treated with a TKI in the adjuvant setting, the overall response rate in 8 metastatic patients was 50% and the complete response rate was 37.5%. The median follow-up period was 29 months. The median progressionfree survival was 21 months, median overall survival was not achieved, and 2 deaths occurred.Conclusions: Our findings suggest that TKI for treatment for metastatic &lt;i&gt;TFE3&lt;/i&gt;-rearranged RCC is efficacious, with an overall response rate of 50% and a median progression-free survival of 21 months.

Oncogenic Roles of Laminin Subunit Gamma-2 in Intrahepatic Cholangiocarcinoma via Promoting EGFR Translation.

Intrahepatic cholangiocarcinoma (iCCA) is a highly lethal biliary epithelial cancer in the liver. Here, Laminin subunit gamma-2 (LAMC2) with important oncogenic roles in iCCA is discovered. In a total of 231 cholangiocarcinoma patients (82% of iCCA patients) across four independent cohorts, LAMC2 is significantly more abundant in iCCA tumor tissue compared to normal bile duct and non-tumor liver. Among 26.3% of iCCA patients, LAMC2 gene is amplified, contributing to its over-expression. Functionally, silencing LAMC2 significantly blocks tumor formation in orthotopic iCCA mouse models. Mechanistically, it promotes EGFR protein translation via interacting with nascent unglycosylated EGFR in the endoplasmic reticulum (ER), resulting in activated EGFR signaling. LAMC2-mediated EGFR translation also depends on its interaction with the ER chaperone BiP via their C-terminus. Together LAMC2 and BiP generate a binding "pocket" of nascent EGFR and facilitate EGFR translation. Consistently, LAMC2-high iCCA patients have poor prognosis in two iCCA cohorts. LAMC2-high iCCA cells are highly sensitive to EGFR tyrosine kinase inhibitors (TKIs) treatment both in vitro and in vivo. Together, these data demonstrate LAMC2 as an oncogenic player in iCCA by promoting EGFR translation and an indicator to identify iCCA patients who may benefit from available EGFR-targeted TKIs therapies.

Analytical Performance Evaluation of a Digital Real-Time PCR for Quantifying Major BCR::ABL1 Transcripts.

Accurate quantification of the BCR::ABL1 transcripts is essential for measurable residual disease (MRD) monitoring in chronic myeloid leukemia (CML) after tyrosine kinase inhibitor (TKI) treatment. This study evaluated the newly developed digital real-time PCR method, Dr. PCR, as an alternative reverse transcription-PCR (qRT-PCR) for MRD detection. The performance of Dr. PCR was assessed using reference and clinical materials. Precision, linearity, and correlation with qRT-PCR were evaluated. MRD levels detected by Dr. PCR were compared with qRT-PCR, and practical advantages were investigated. Dr. PCR detected MRD up to 0.0032%IS (MR4.5) with excellent precision and linearity and showed a strong correlation with qRT-PCR results. Notably, Dr. PCR identified higher levels of MRD in 12.7% (29/229) of patients than qRT-PCR, including six cases of MR4, which is a critical level for TKI discontinuation. Dr. PCR also allowed for sufficient ABL1 copies in all cases, while qRT-PCR necessitated multiple repeat tests in 3.5% (8/229) of cases. Our study provides a body of evidence supporting the clinical application of Dr. PCR as a rapid and efficient method for assessing MRD in patients with CML under the current treatment regimen.

Abstract 6295: Role of MAPK11 in the protective mechanisms against toxicity of tyrosine kinase inhibitors

Abstract Introduction and purpose of the study: Targeted therapies with Tyrosine Kinase Inhibitors (TKIs) have drastically improved the survival of cancer patients. However, long term exposure to TKIs has been associated with severe adverse events such as heart failure, impairing patient survival and life quality, and limiting treatment options. Cardioprotective effect of MAPK11 has been described against cardiac ischemic disease. In addition, MAPK11 has also been reported as an important mediator in cancer development and progression. Therefore the aim of this study is to evaluate the potential therapeutic and dual anti-cancer and cardio-protective effect of MAPK11 inhibition during TKI treatment. Experimental procedures: For this study we used the TKI ponatinib as a paradigm of cardiac toxicity. Ponatinib has been used as a gold standard therapy for the drug resistant type of Chronic Myeloid Leukemia (CML) due to T315I-ABL1 mutation, and has been associated with high risk of cardiac toxicity. We performed in vitro functional assays to evaluate the cardiotoxicity and cardiac protection using human iPSC-cardiomyocytes (hiPSC-CMs), and anti-cancer effect in T315I mutated KCL-22 CML cells. The cardiotoxicity was evaluated by impairment of cardiomyocytes contractile function during TKI (ponatinib) treatment, the cardiac-protection was evaluated by restoration of contractile function post-inhibition of MAPK11 with RNA silencing (siRNA) technique. The anti-cancer effect was evaluated using a cell viability and proliferation assay during inhibition of MAPK11 by siRNA and ABL1 inhibition as a positive control. Summary of unpublished data: Pretreatment with siRNA MAPK11 inhibition significantly improved the contractile function of the cardiomyocytes during treatment with ponatinib when compared to those that did not receive MAPK11 inhibition. Moreover, when compared to the positive control of siRNA ABL1 inhibition, the MAPK11 inhibition showed similar anti-cancer effect in the T315I mutated KCL-22 CML cells proliferation and survival assay. Conclusions: Our study suggests that the inhibition of MAPK11 is a potential druggable therapeutic target with dual action of anti-cancer effect for the mutant form of CML, as well as a substantial protective effect against the cardiac toxicity associated with the TKI ponatinib that could bring insights in the development of safer oncological drugs. Citation Format: Anna Pavlovna Hnatiuk, David Staudt, Mark Mercola. Role of MAPK11 in the protective mechanisms against toxicity of tyrosine kinase inhibitors [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 6295.

Abstract 7206: Inhibition of CAD, an enzyme of de novo pyrimidine synthesis, to overcome EGFR-TKI resistance in NSCLC

Abstract Given the fast-growing cancer cells, there is an increased demand for large amounts of energy and nucleotides for DNA and RNA synthesis. Thus, targeting nucleotide metabolism, specifically de novo nucleotide biosynthesis, is a promising strategy for cancer treatment. Hyperactivation of Carbamoyl-phosphate synthetase, aspartate transcarbamylase (CAD), a key enzyme catalyzing the first three steps of de novo pyrimidine synthesis, is a common event in tumors and has been associated with chemoresistance in tumors. Our analysis, using TCGA data, revealed that increased expression of CAD is associated with poor prognosis in non-small cell lung cancer (NSCLC). Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have demonstrated significant benefits to patients with NSCLC harboring EGFR-activating mutations; however, acquired resistance limits their long-term efficacy. Therefore, it remains urgent to discover the underlying mechanisms for discovering novel therapeutic strategies for overcoming TKI resistance. Our previous findings demonstrated that blockade of S6K1 overcomes acquired resistance to EGFR-TKIs in NSCLC. It was reported that S6K1 is involved in de novo pyrimidine biosynthesis. In this study, we aimed to investigate whether CAD mediates S6K1-induced EGFR-TKI resistance in NSCLC. Immunohistochemistry analysis on a tissue microarray of lung adenocarcinoma tissues indicated that increased co-expression of p-CAD and S6K1 proteins is associated with clinicopathological parameters and poor survival outcomes. Our in vitro results showed an increased expression level of CAD and p-CAD proteins in TKI-resistant cells compared with parental cells upon TKI treatment. Knockdown of CAD by siRNA led to sensitizing TKI-resistant cells to osimertinib, as indicated by BrdU cell proliferation assay. Inhibition of S6K1 by a siRNA or specific inhibitors PF-470867 and LY2584702 effectively reduced the phosphorylation levels of CAD protein in TKI-resistant cells, suggesting that S6K1 may serve as an upstream regulator of CAD for TKI resistance. The String database predicted a protein-protein interaction between S6K1 and CAD. Indeed, our co-immunoprecipitation (co-IP) results revealed a direct association between S6K1 and CAD proteins. Importantly, TKI treatment enhanced the binding between S6K1 and CAD. Taken together, these findings provide evidence that CAD may mediate S6K1-mediated EGFR-TKI resistance in NSCLC. Our ongoing and future work will assess whether inhibition of CAD sensitizes resistant cells to TKI in vivo and elucidate the associated mechanism. Citation Format: Leili Saeednejad Zanjani, Lei Zhao, Shaomin Wang, Margot Federoff, Xin Sun, Jun He. Inhibition of CAD, an enzyme of de novo pyrimidine synthesis, to overcome EGFR-TKI resistance in NSCLC [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 7206.

Chronic Myeloid Leukemia Presenting with Megakaryocytic Blast Crisis: a Case Report with a Favorable Outcome

Chronic myeloid leukemia (CML) belongs to the chronic myeloproliferative neoplasms, a clonal disorder of pluripotent hematopoietic stem cells, arising because of a hallmark genetic anomaly- reciprocal translocation between chromosomes 9 and 22, known as the Philadelphia chromosome, which generates the BCR::ABL fusion gene. The disease can have a biphasic/triphasic evolution, comprised of an accelerated phase and a terminal blast phase (usually biphasic when blastic phase is lymphoid in nature). Most cases present during the chronic phase of the disease, with only 10% of cases presenting in the blast phase. Megakaryocytic blast crisis is an unusual form of presentation, accounting for less than 3% of cases and it commonly carries an unfavorable prognosis compared to the classic myeloid, lymphoid or even mixed lineage blast crises. Aim: To bring forth an unusual case of CML presenting with megakaryocytic blast crisis and the therapeutic challenges associated with this particular presentation, unexpectedly ending with a favorable outcome. Matherial and methods: we hereby present the case of a 50 year old female patient, diagnosed in 2015 with CML- megakaryocytic blast crisis, who underwent treatment with a tyrosine kinase inhibitor (TKI)- imatinib and intensive chemotherapy regimen 3+7, without satisfactory response. A second induction chemotherapy regimen followed (MEC), alltogether with the same TKI and cytoreductive treatment (hydroxyurea/HU), but still without achieving a complete remission. Thus, the TKI was switched to dasatinib and complete normalisation of blood counts followed (including thrombocytes). However, there was still inadequate molecular and cytogenetic response. Therefore, TKI dosage was increased and after 4 months the patient achieved complete remission, with no detectable BCR::ABL transcript. She spent 9 years on the same TKI until important pleural effusion developed, which required switching to another 2nd generation TKI- bosutinib, based on the patients age, genetic profile and commorbidities. She is still in complete remission without detectable BCR::ABL transcript/Philadelphia chromosome to this day (2024). Results and conclusions: this is the case of a rare presentation of CMLmegakaryocytic blast crisis, who underwent both TKI and intensive chemotherapy induction regimens, marked by a favorable unexpected outcome.

Abstract 2724: BCG020, a novel bispecific antibody targeting EGFR and CD70, is effective against EGFR and CD70 high expressed tumors

Abstract The epidermal growth factor receptor (EGFR) is highly expressed across a wide range of different cancers, and is a known driver of cancer growth; EGFR upregulation is frequently associated with adverse prognosis. Many patients undergoing EGFR-TKI (tyrosine kinase inhibitors) treatment will acquire resistance, which can be accompanied by increased expression of CD70 in some cancers. Simultaneous engagement of both EGFR and CD70 with a bispecific antibody (bsAb) is a potential strategy to overcome such resistance and achieve greater efficacy. To explore this strategy, we developed a novel IgG1 bsAb, BCG020, targeting EGFR and CD70. The parental EGFR antibody and CD70 antibody were developed from fully human common light chain antibody mice (RenLite®). When compared to EGFR benchmarks, the parental EGFR antibody exhibits similar affinity to both human and cynomolgus monkey EGFR, similar internalization activity in EGFR+ tumor cell lines, and superior blocking activity of EGF to EGFR in vitro. Furthermore, the EGFR parental antibody demonstrates good stability. The parental CD70 antibody exhibits high affinity to both human and monkey CD70, with superior internalization activity to benchmark antibody in CD70+ tumor cell lines, as well as superior blockade of CD70-induced signaling of CD27-Luc when compared to benchmark antibodies. When assembled into a bsAb, BCG020 exhitibs the same high affinity as both parental antibodies, with higher internalization activity than parental antibodies and benchmark antibodies. To evaluate the efficacy of BCG020 in vivo, we established cell line-derived xenograft (CDX) models in immunodeficient (B-NDG) mice. We observed that BCG020 treatment (10 mg/kg) potently inhibited growth of EGFR+CD70+ tumors. Taken together, these data indicate that BCG020 is a first-in-class bispecific antibody with potential to treat solid tumors with high expression of EGFR and CD70. Citation Format: Yongfei Yang, Xiaoxia Sun, Ziyan Li, Yue Yan, Linpeng Xu, Xiaoxue Wu, Luheng Du, Ying Zhu, Chaoshe Guo, W. Frank An. BCG020, a novel bispecific antibody targeting EGFR and CD70, is effective against EGFR and CD70 high expressed tumors [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 2724.

A Radiomics-clinical Nomogram based on CT Radiomics to Predict Acquired T790M Mutation Status in Non-small Cell Lung Cancer Patients.

To develop and validate a radiomics-clinical nomogram for the detection of the acquired T790M mutation in patients with advanced non-small cell lung cancer (NSCLC) with resistance after the duration of first-line epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI) treatment. Thoracic CT was collected from 120 advanced NSCLC patients who suffered progression on first- or second-generation TKIs. Radiomics signatures were retrieved from the entire tumor. Pearson correlation and the least absolute shrinkage and selection operator (LASSO) regression method were adopted to choose the most suitable radiomics features. Clinical and radiological factors were assessed using univariate and multivariate analysis. Three Machine Learning (ML) models were constructed according to three classifiers, including Logistic Regression (LR), Support Vector Machine (SVM), and RandomForest (RF), combining clinical and radiomic features. A nomogram combining clinical features and the rad score signature was built. The predictive ability of the nomogram was assessed by the ROC curve, calibration curve, and decision curve analysis (DCA). Multivariate regression analysis showed that two clinicopathological characteristics and two radiological features were highly correlated with the acquired T790M mutation, including the progression-free survival (PFS) of first-line EGFR TKIs (P = 0.029), the initial EGFR profile (P = 0.01), vascular convergence (P = 0.043), and air bronchogram (P = 0.030). The AUCs of clinical, radiomics, and combined models using RF classifiers for T790M mutation detection were 0.951 (95% confidence interval [CI] 0.911,0.991), 0.917 (95%CI 0.856,0.978), and 0.961 (95%CI 0.927,0.995) in the training cohort, respectively, higher than those of other classifier models.The calibration curve and Hosmer-Lemeshow Test showed good calibration power, and the DCA demonstrated a significant net benefit. A radiomics-clinical nomogram based on CT radiomics proved valuable in non-invasively and efficiently predicting the acquired T790M mutation in patients who suffered progression on first-line TKIs.

Abstract 1958: EGFR and mTOR signaling facilitate RET-independent resistance to selective RET-TKIs

Abstract RET fusions are an oncogenic driver mutation occurring in 1-2% non-small cell lung cancer (NSCLC). Currently, RET-selective tyrosine kinase inhibitors (TKIs) selpercatinib and pralsetinib are approved for this patient population, demonstrating favorable antitumor activity and safety profiles in advanced RET fusion-positive NSCLC. However, tumors eventually become refractory to selective RET inhibitor monotherapy. We sought to identify signaling pathways which mediate RET-independent acquired resistance to RET inhibitors and effective therapeutic combinations to overcome resistance. Using LC-2/ad (CCDC6-RET) NSCLC cells, we assessed the expression and activation of critical signaling pathways at a proteomic level following RET knockdown using reverse-phase protein array. RET knockdown resulted in rapidly increased adaptive upregulation of EGFR, HER2, MET, mTOR and MEK pathway signaling; observations were confirmed by Western Blotting. To determine whether EGFR or MET signaling facilitate RET inhibitor resistance, LC-2/ad and NCCE-TH1101 (KIF5B-RET) NSCLC cells were treated with increasing concentrations of selpercatinib or pralsetinib with or without ligands for these receptors, EGF or HGF respectively, and after five days cell viability was measured by CellTiter Glo. EGFR and MET signaling promoted RET TKI resistance in both cell lines. Next, to evaluate whether blockade of EGFR or MET signaling could enhance the activity of RET inhibitors, we treated LC-2/ad and NCCE-TH1101 cells with RET TKIs alone or in combination with the EGFR TKI erlotinib or poziotinib, or the MET inhibitor SU11274. We observed an additive effect with EGFR but not MET inhibitors when combined with RET TKIs. Western blot analysis revealed that EGFR signaling could reactivate mTOR and MAPK signaling after RET TKI treatment. Therefore, we next tested whether inhibition of these downstream pathways might enhance RET TKI sensitivity. We observed that treatment of LC-2/ad and NCCE-TH1101 cells with an mTOR inhibitor (everolimus) or a MEK inhibitor (trametinib) in combination with RET TKIs increased the anti-tumor activity or RET inhibitors. Finally, we established cells with acquired resistance to selpercatinib and pralsetinib. RET TKI resistant cells did not harbor secondary RET fusion mutations but underwent epithelial to mesenchymal transition and exhibited pan-RET inhibitor resistance. Moreover, RET TKI resistant cells showed increased cell surface expression of EGFR and MET by flow cytometry. RET TKI resistant cells were sensitive to mTOR or MEK inhibitors in combination with RET TKIs. Collectively, our findings indicate that in RET-fusion positive NSCLC tumor cells, activation of bypass pathways including the EGFR, MAPK, mTOR pathways may facilitate RET inhibitor resistance and that blockade of bypass pathways may enhance the efficacy of selective RET inhibitors and overcome acquired RET TKI resistance. Citation Format: Tomohiro Takehara, Monique B. Nilsson, Ximeng Liu, Hibiki Udagawa, Naoto Morikawa, Alissa Poteete, Junqin He, Xiaoxing Yu, Thiru Arumugam, Koichi Goto, John V. Heymach. EGFR and mTOR signaling facilitate RET-independent resistance to selective RET-TKIs [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 1958.

Outcomes and pathologic response of primary lung cancer treated with tyrosine kinase inhibitor/immune checkpoint inhibitor before salvage surgery.

Advances in primary lung cancer drug therapy have extended patients' survival, including patients with stage IV disease. This study assessed the safety and effectiveness of salvage surgery following tyrosine kinase inhibitor (TKI) or immune checkpoint inhibitor (ICI) therapy in primary lung cancer. A retrospective chart review was conducted of 2050 primary lung cancer surgeries performed at our institution between 2012 and 2022. The study included patients who underwent salvage surgery for unresectable lesions that became resectable or localized residual lesions after treatment. We investigated patients' clinicopathological characteristics, therapeutic responses, and survival outcomes. We identified eight cases of salvage surgery after TKI treatment and eight cases after ICI treatment. Five patients experienced early recurrence after surgery; however, the long-term outcome in the post-TKI group was favorable, with a median overall survival (OS) of 66 (range: 28-80) months. Postoperative recurrence was confined to local lymph node recurrence in one patient in the post-ICI group. Despite the relatively short observation period, the long-term prognosis remained promising, with a median OS of 18.7 (range: 9.7-55.8) months. Salvage surgery after TKI or ICI treatment can be safely performed, and the OS may be favorable.

The GIST of it all: management of gastrointestinal stromal tumors (GIST) from the first steps to tailored therapy. A bibliometric analysis

PurposeImprovement of patient care is associated with increasing publication numbers in biomedical research. However, such increasing numbers of publications make it challenging for physicians and scientists to screen and process the literature of their respective fields. In this study, we present a comprehensive bibliometric analysis of the evolution of gastrointestinal stromal tumor (GIST) research, analyzing the current state of the field and identifying key open questions going beyond the recent advantages for future studies to assess.MethodsUsing the Web of Science Core Collection, 5040 GIST-associated publications in the years 1984–2022 were identified and analyzed regarding key bibliometric variables using the Bibliometrix R package and VOSviewer software.ResultsGIST-associated publication numbers substantially increased over time, accentuated from year 2000 onwards, and being characterized by multinational collaborations. The main topic clusters comprise surgical management, tyrosine kinase inhibitor (TKI) development/treatment, diagnostic workup, and molecular pathophysiology. Within all main topic clusters, a significant progress is reflected by the literature over the years. This progress ranges from conventional open surgical techniques over minimally invasive, including robotic and endoscopic, resection techniques to increasing identification of specific functional genetic aberrations sensitizing for newly developed TKIs being extensively investigated in clinical studies and implemented in GIST treatment guidelines. However, especially in locally advanced, recurrent, and metastatic disease stages, surgery-related questions and certain specific questions concerning (further-line) TKI treatment resistance were infrequently addressed.ConclusionIncreasing GIST-related publication numbers reflect a continuous progress in the major topic clusters of the GIST research field. Especially in advanced disease stages, questions related to the interplay between surgical approaches and TKI treatment sensitivity should be addressed in future studies.

European Stop Tyrosine Kinase Inhibitor Trial (EURO-SKI) in Chronic Myeloid Leukemia: Final Analysis and Novel Prognostic Factors for Treatment-Free Remission.

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.The European Stop Kinase Inhibitors (EURO-SKI) study is the largest clinical trial for investigating the cessation of tyrosine kinase inhibitors (TKIs) in patients with chronic myeloid leukemia in stable deep molecular remission (DMR). Among 728 patients, 434 patients (61%; 95% CI, 57 to 64) remained in major molecular response (MMR) at 6 months and 309 patients of 678 (46%; 95% CI, 42 to 49) at 36 months. Duration of TKI treatment and DMR before TKI stop were confirmed as significant factors for the prediction of MMR loss at 6 months. In addition, the type of BCR::ABL1 transcript was identified as a prognostic factor. For late MMR losses after 6 months, TKI treatment duration, percentage of blasts in peripheral blood, and platelet count at diagnosis were significant factors in multivariate analysis. For the entire study period of 36 months, multiple logistic regression models confirmed duration of treatment, blasts, and transcript type as independent factors for MMR maintenance. In addition to the duration of treatment, transcript type as well as blasts in peripheral blood at diagnosis should be considered as important factors to predict treatment-free remission.

Tet methylcytosine dioxygenase 2 (TET2) deficiency elicits EGFR-TKI (tyrosine kinase inhibitors) resistance in non-small cell lung cancer

Despite epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI) have shown remarkable efficacy in patients with EGFR-mutant non-small cell lung cancer (NSCLC), acquired resistance inevitably develops, limiting clinical efficacy. We found that TET2 was poly-ubiquitinated by E3 ligase CUL7FBXW11 and degraded in EGFR-TKI resistant NSCLC cells. Genetic perturbation of TET2 rendered parental cells more tolerant to TKI treatment. TET2 was stabilized by MEK1 phosphorylation at Ser 1107, while MEK1 inactivation promoted its proteasome degradation by enhancing the recruitment of CUL7FBXW11. Loss of TET2 resulted in the upregulation of TNF/NF-κB signaling that confers the EGFR-TKI resistance. Genetic or pharmacological inhibition of NF-κB attenuate the TKI resistance both in vitro and in vivo. Our findings exemplified how a cell growth controlling kinase MEK1 leveraged the epigenetic homeostasis by regulating TET2, and demonstrated an alternative path of non-mutational acquired EGFR-TKI resistance modulated by TET2 deficiency. Therefore, combined strategy exploiting EGFR-TKI and inhibitors of TET2/NF-κB axis holds therapeutic potential for treating NSCLC patients who suffered from this resistance.