Second-generation Tyrosine Kinase Inhibitors Research Articles

L718Q/V mutation in exon 18 of EGFR mediates resistance to osimertinib: clinical features and treatment

Osimertinib, a mutant-specific third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), is emerging as the preferred first-line of treatment for EGFR-mutant lung cancer. However, osimertinib resistance inevitably develops among patients treated with the drug. The modal resistance mechanisms of osimertinib include the occurrence of epithelial transition factor (c-MET) amplification and C797S mutation, whereas rare mutations are presented as case reports. Recently, the L718Q/V mutation in exon 18 of EGFR has been reported to contribute to one of the possible mechanisms of resistance. The clinical features and subsequent treatment strategies for this mutation require further research. This study retrospectively enrolled NSCLC patients with the L718Q/V mutation from 2017 to 2021 at the Cancer Hospital of the University of the Chinese Academy of Sciences (Zhejiang Cancer Hospital), as well as additional patients with the same mutation from PubMed literature, to summarize the clinical features of the mutation. The association between the detection of L718Q/V and resistance to osimertinib, as well as impacts on the therapeutic process and outcome, was analyzed. We included a total of two patients diagnosed at Zhejiang Cancer Hospital and twelve patients from the literature. Of the fourteen total patients, 64.3% were male and 35.7% were female. The average age of the group was 60.2 years (range 45–72). A history of tobacco use was common among the group. In all of the cases we considered, the L718Q/V mutation was secondary to the L858R mutation. The second-generation TKI afatinib was found to provide a high disease control rate (DCR) (85.7%, 6/7) and relatively low objective response rate (ORR) (42/9%, 3/7). The median progression free survival (mPFS) for this treatment reached 2 months (1–6 months). The patients failed to benefit from chemotherapy combined with immunotherapy or other TKI medications. Due to the limited number of cases considered in this study, future studies should explore drugs that more precisely target the L718Q/V mutation of EGFR exon 18.

Chronic Myeloid Leukemia: Part II—Cost of Care Among Patients in Advanced Phases or Later Lines of Therapy in Chronic Phase in the United States from a Commercial Perspective

Background: Tyrosine kinase inhibitors (TKIs) are the standard-of-care treatment for chronic myeloid leukemia in chronic phase (CML-CP). Despite advances in therapy, there remains a proportion of patients with CML-CP that are refractory/intolerant to TKIs, and these patients cycle through multiple lines of therapy. Moreover, even with TKIs, some patients progress to accelerated phase/blast crisis (AP/BC), which is associated with particularly poor clinical outcomes. Objectives: To describe real-world treatment patterns, healthcare resource utilization (HRU), and costs of patients with CML-CP reaching later lines of therapy or progressing to AP/BC in the United States. Methods: Adult CML patients from administrative claims data (January 1, 2000–June 30, 2019) were classified by health state: on third-line (CML-CP On Treatment), on fourth or later lines (CML-CP Post-Discontinuation), or progressed to AP/BC (CML-AP/BC). Outcomes were assessed by health state. Results: There were 296 (4620 patient-months), 83 (1644 patient-months), and 949 (25 593 patient-months) patients classified in the CML-CP On Treatment, CML-CP Post-Discontinuation, and CML-AP/BC cohorts, respectively. Second-generation TKIs (nilotinib, dasatinib, and bosutinib) were most commonly used in the CML-CP On Treatment (69.1% of patient-months) and CML-CP Post-Discontinuation cohorts (59.1% of patient-months). Three-month outpatient incidence rates (IRs) were 7.6, 8.3, and 7.0 visits in the CML-CP On Treatment, CML-CP Post-Discontinuation, and CML-AP/BC cohort, respectively, with mean costs of $597 per service. Three-month inpatient IRs were 0.6, 0.7, and 1.4 days in the CML-CP On Treatment, CML-CP Post-Discontinuation, and CML-AP/BC cohort, respectively, with mean costs of $5892 per day. Mean hematopoietic stem cell transplantation cost was $352 333; mean 3-month terminal care cost was $107 013. Discussion: Cost of CML care is substantial among patients with CML reaching third-line, fourth or later lines, or progressing to AP/BC, suggesting that the disease is associated with a significant economic and clinical burden. From third-line to fourth or later lines, HRU was observed to increase, and the incidence of inpatient days was particularly high for those who progressed to AP/BC. Conclusion: In this study, patients with CML cycling through TKIs in later lines of therapy or progressing to AP/BC experienced substantial HRU and costs, suggesting unmet treatment needs.

Chronic Myeloid Leukemia: Part II-Cost of Care Among Patients in Advanced Phases or Later Lines of Therapy in Chronic Phase in the United States from a Commercial Perspective.

Background: Tyrosine kinase inhibitors (TKIs) are the standard-of-care treatment for chronic myeloid leukemia in chronic phase (CML-CP). Despite advances in therapy, there remains a proportion of patients with CML-CP that are refractory/intolerant to TKIs, and these patients cycle through multiple lines of therapy. Moreover, even with TKIs, some patients progress to accelerated phase/blast crisis (AP/BC), which is associated with particularly poor clinical outcomes.Objectives: To describe real-world treatment patterns, healthcare resource utilization (HRU), and costs of patients with CML-CP reaching later lines of therapy or progressing to AP/BC in the United States.Methods: Adult CML patients from administrative claims data (January 1, 2000–June 30, 2019) were classified by health state: on third-line (CML-CP On Treatment), on fourth or later lines (CML-CP Post-Discontinuation), or progressed to AP/BC (CML-AP/BC). Outcomes were assessed by health state.Results: There were 296 (4620 patient-months), 83 (1644 patient-months), and 949 (25 593 patient-months) patients classified in the CML-CP On Treatment, CML-CP Post-Discontinuation, and CML-AP/BC cohorts, respectively. Second-generation TKIs (nilotinib, dasatinib, and bosutinib) were most commonly used in the CML-CP On Treatment (69.1% of patient-months) and CML-CP Post-Discontinuation cohorts (59.1% of patient-months). Three-month outpatient incidence rates (IRs) were 7.6, 8.3, and 7.0 visits in the CML-CP On Treatment, CML-CP Post-Discontinuation, and CML-AP/BC cohort, respectively, with mean costs of $597 per service. Three-month inpatient IRs were 0.6, 0.7, and 1.4 days in the CML-CP On Treatment, CML-CP Post-Discontinuation, and CML-AP/BC cohort, respectively, with mean costs of $5892 per day. Mean hematopoietic stem cell transplantation cost was $352 333; mean 3-month terminal care cost was $107 013.Discussion: Cost of CML care is substantial among patients with CML reaching third-line, fourth or later lines, or progressing to AP/BC, suggesting that the disease is associated with a significant economic and clinical burden. From third-line to fourth or later lines, HRU was observed to increase, and the incidence of inpatient days was particularly high for those who progressed to AP/BC.Conclusion: In this study, patients with CML cycling through TKIs in later lines of therapy or progressing to AP/BC experienced substantial HRU and costs, suggesting unmet treatment needs.

Pharmacokinetics, Bioequivalence, and Safety Studies of a Generic Selective Tyrosine Kinase Inhibitor Nilotinib Capsule Versus a Branded Product in Healthy Chinese Volunteers.

Nilotinib, a second-generation tyrosine kinase inhibitor (TKI), has been approved in the United States and Europe as a treatment for patients with newly diagnosed chronic myeloid leukemia (CML)-chronic phase (CP) and patients with CML-CP or chronic myeloid leukemia-accelerated phase (CML-AP) who are resistant or intolerant to imatinib (a first-generation TKI). This study compared the bioequivalence and safety of the test nilotinib capsule and reference nilotinib capsule (Tasigna, Novartis) in healthy Chinese volunteers under fasting conditions for marketing authorization in China. The results of the study are reported for the first time. This was a single-dose, randomized, open-label, two-period, and cross-over study. Thirty healthy volunteers were randomly assigned to receive a single dose of a 200-mg test or reference capsule under fasting conditions in each period with a 10-day washout. Plasma samples were analyzed with liquid chromatography-tandem mass spectrometry. Pharmacokinetic parameters were calculated with WinNonlin software. The geometric mean ratio and the corresponding 90% confidence intervals of Cmax , AUC0-t , and AUC0-∞ for nilotinib between the two fixed-dose combination formulations were within the bioequivalence acceptance range of 80%-125%, therefore the generic and branded formulations were bioequivalent in healthy Chinese volunteers.

Evaluation of Treatment Efficacy of Tyrosine Kinase Inhibitors in Rare Single EGFR Exon 21 L861Q Mutation: Single Center Experience.

OBJECTIVE:Epidermal growth factor receptor mutations are the second most common oncogenic driver event in non-small cell lung cancer. We aimed to compare the first generation erlotinib treatment with the second generation afatinib treatment in patients with non-small cell lung cancer with epidermal growth factor receptor exon 21 L861Q mutation.MATERIAL AND Methods:Progression-free survival and overall survival of 30 non-small cell lung cancer patients treated with erlotinib or afatinib due to single epidermal growth factor receptor L861Q positivity were compared retrospectively. The number of patients included in the first, second, and third treatment line was 15 (50.0%), 11 (36.7%), and 4 (13.3%), respectively.Results:There were 23 patients in the erlotinib arm and 7 patients in the afatinib arm. Median progression-free survival was 12.8 months in the erlotinib group and 9.3 months in the afatinib group. Median overall survival in erlotinib and afatinib groups was 77.9 months and 30.3 months, respectively. No statistically significant difference was found in the comparison of these survival times. Conclusion:Survival times of erlotinib and afatinib treatment are similar in patients with a single epidermal growth factor receptor L861Q mutation. In patients receiving tyrosine kinase inhibitors treatment, the female gender has a positive effect on progression-free survival, and being a non-smoker has a positive effect on overall survival. In patients with rare mutation exon 21 L861Q positivity, both first-generation and second-generation tyrosine kinase inhibitors should be considered.

Discovery of BLU-945, a Reversible, Potent, and Wild-Type-Sparing Next-Generation EGFR Mutant Inhibitor for Treatment-Resistant Non-Small-Cell Lung Cancer.

While epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have changed the treatment landscape for EGFR mutant (L858R and ex19del)-driven non-small-cell lung cancer (NSCLC), most patients will eventually develop resistance to TKIs. In the case of first- and second-generation TKIs, up to 60% of patients will develop an EGFR T790M mutation, while third-generation irreversible TKIs, like osimertinib, lead to C797S as the primary on-target resistance mutation. The development of reversible inhibitors of these resistance mutants is often hampered by poor selectivity against wild-type EGFR, resulting in potentially dose-limiting toxicities and a sub-optimal profile for use in combinations. BLU-945 (compound 30) is a potent, reversible, wild-type-sparing inhibitor of EGFR+/T790M and EGFR+/T790M/C797S resistance mutants that maintains activity against the sensitizing mutations, especially L858R. Pre-clinical efficacy and safety studies supported progression of BLU-945 into clinical studies, and it is currently in phase 1/2 clinical trials for treatment-resistant EGFR-driven NSCLC.

Simultaneous quantification of dasatinib, nilotinib, bosutinib, and ponatinib using high-performance liquid chromatography-Photodiode array detection.

BackgroundDasatinib, nilotinib, and bosutinib, second‐generation tyrosine kinase inhibitors (TKIs), and ponatinib, a third‐generation TKI, are approved pharmaceuticals used in the treatment of chronic myeloid leukemia (CML). Although liquid chromatography‐tandem mass spectrometry assays for simultaneous quantification of the four TKIs in human serum have been reported in the literature, a high‐performance liquid chromatography (HPLC) assay that simultaneously quantifies these compounds has not yet been developed. This study aims to establish and validate an efficient HPLC analytical method using a photodiode array (PDA) detector for the simultaneous quantification of the four TKIs.MethodsCalibration standards were prepared by serial dilution of serum samples containing the four TKIs, followed by solid‐phase extraction. The four TKIs were eluted in order within 10 min using a binary HPLC gradient system.ResultsThe calibration ranges were 2–500 ng/ml for dasatinib, 100–5000 ng/ml for nilotinib, and 10–500 ng/ml for bosutinib and ponatinib. Intra‐day and inter‐day precision and accuracy values were found to be in accordance with the U.S. Food and Drug Administration guidelines. The recovery rates were 92.9%–96.0%, 80.7%–86.1%, 91.6%–99.0%, and 86.4%–92.6% for dasatinib, nilotinib, bosutinib, and ponatinib, respectively.ConclusionTo the best of our knowledge, this is the first report of an HPLC‐PDA analytical method that allows efficient simultaneous quantification of the four TKIs in the serum of patients with CML. We believe that the method developed herein can improve the efficiency of therapeutic drug monitoring in patients with CML in clinical practice.

Audit of Molecular Mechanisms of Primary and Secondary Resistance to Various Generations of Tyrosine Kinase Inhibitors in Known Epidermal Growth Factor Receptor-Mutant Non-small Cell Lung Cancer Patients in a Tertiary Centre

AimsPresently, three generations of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are approved against oncogene addicted EGFR-mutant non-small cell lung cancer (NSCLC). Patients with actionable EGFR mutations invariably develop resistance. This resistance can be intrinsic (primary) or acquired (secondary). Materials and methodsThis was a retrospective study carried out between January 2016 and April 2021 analysing 486 samples of NSCLC for primary and secondary resistance to first- (erlotinib, gefitinb), second- (afatinib) and/or third-generation (osimertinib) TKIs in EGFR-mutant NSCLCs by next generation sequencing (NGS). Tissue NGS was carried out using the Thermofischer Ion Torrent™ Oncomine™ Focus 52 gene assay; liquid biopsy NGS was carried out using the Oncomine Lung Cell-Free Total Nucleic Acid assay. All cases were previously tested for a single EGFR gene with the Therascreen® EGFR RGQ PCR kit. ResultsThe results were divided into four groups: (i) group 1: primary resistance to first- and/or second-generation TKIs. This group, with 21 cases, showed EGFR exon 20 insertions, dual, complex mutations and variant of unknown significance, de novo MET gene amplification besides other mutations. (ii) Group 2: primary resistance to third-generation TKIs. This group showed two cases, with one showing dual EGFR mutation (L858R and E709A) and EGFR gene amplification. (iii) Group 3: secondary resistance to first- and second-generation TKIs. This group had 27 cases, which were previously reported negative for EGFR T790M by single gene testing. Significant findings were MET gene amplification in four cases, with one also showing MET exon 14 skipping mutation. Three cases showed small cell change and one showed loss of primary mutation. (iv) Group 4: secondary resistance to third-generation TKIs. The latter group was further subgrouped into group 4A: secondary resistance to osimertinib (third-generation TKI) when offered as second-line therapy after first- and second-generation TKIs on detection of T790M mutation. This group had 15 cases. EGFR T790M mutation was lost in 10 (10/15; 67%) cases and was retained in five cases. Patients with T790M loss experienced early resistance (6.9 months versus 12.6 months mean, P = 0.0024) compared with cases that retained T790M. Two cases gained MET amplification as the resistance mechanisms. Other mutations that were found when EGFR T790M was lost were in FGFR3, KRAS, PIK3CA, CTNNB1, BRAF genes. One case had EML4-ALK translocation. Two cases showed driver EGFR deletion 19, retained T790M and C797S mutation in Cis form. Group 4B: secondary resistance to osimertinib (when given as first-line therapy) in EGFR-mutant NSCLC. This group had three cases. The duration of osimertinib treatment ranged from 11 to 17 months. Two patients showed additional C797S mutation along with primary EGFR mutation. ConclusionThis study shows the wide spectrum of primary and secondary EGFR resistance mechanisms to first, second and third generation of TKIs and helps us to identify newer therapeutic targets that could carry forward the initial advantage offered by EGFR TKIs.

Can CT Radiomics Detect Acquired T790M Mutation and Predict Prognosis in Advanced Lung Adenocarcinoma With Progression After First- or Second-Generation EGFR TKIs?

ObjectiveTo explore the potential of CT radiomics in detecting acquired T790M mutation and predicting prognosis in patients with advanced lung adenocarcinoma with progression after first- or second-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) therapy.Materials and MethodsContrast-enhanced thoracic CT was collected from 250 lung adenocarcinoma patients (with acquired T790M mutation, n = 146, without mutation, n = 104) after progression on first- or second-generation TKIs. Radiomic features were extracted from each volume of interest. The maximum relevance minimum redundancy and the least absolute shrinkage and selection operator (LASSO) regression method were used to select the optimized features in detecting acquired T790M mutation. Univariate Cox regression and LASSO Cox regression were used to establish the radiomics model to predict the progression-free survival of osimertinib treatment. Finally, nomograms (which) combined clinical factors with radscore to predict the acquired T790M mutation and prognosis were built separately. In addition, the two nomograms were validated by the concordance index (C-index), decision curve analysis (DCA), and calibration curve analysis where appropriate.ResultsClinical factors including the progression-free survival of first-line EGFR TKIs, EGFR mutation, and N stage and 12 radiomic features were useful in predicting the acquired T790M mutation. The area under the receiver operating characteristic curves (AUC) of clinical, radiomics, and nomogram models were 0.70, 0.74, and 0.78 in the training set and 0.71, 0.71, and 0.76 in the validation set, respectively. The DCA and calibration curve analysis demonstrated a good performance of the nomogram model. Clinical factors including age and first-generation EGFR TKIs and 12 radiomic features were useful in patients’ outcome prediction. The C-index of the combined nomogram was 0.686 in the training set and 0.630 in the validation set, respectively. Calibration curves demonstrated a relatively poor performance of the nomogram model.ConclusionNomogram combined clinical factors with radiomic features might be helpful to detect whether patients developed acquired T790M mutation or not after progression on first- or second-generation EGFR TKIs. Nomogram prognostic model combined clinical factors with radiomic features might have a limited value in predicting the survival of patients harboring acquired T790M mutation treated with osimertinib.

Efficacy and Safety of SH-1028 in Patients With EGFR T790M-Positive NSCLC: A Multicenter, Single-Arm, Open-Label, Phase 2 Trial

IntroductionAs a novel third-generation EGFR tyrosine kinase inhibitor (TKI), SH-1028 (formerly oritinib) is developed to inhibit both sensitizing EGFR mutations and EGFR T790M mutation. MethodsThis was a multicenter, single-arm, open-label, phase 2 trial (NCT03823807). Eligible patients were those with advanced NSCLC with centrally confirmed EGFR T790M mutation who progressed after first- or second-generation EGFR TKIs or with primary EGFR T790M mutations. Each patient received SH-1028 tablets orally at 200 mg/d until disease progression or intolerable toxicity. Tumor response was evaluated every 6 weeks per the Response Evaluation Criteria in Solid Tumors, version 1.1. The primary end point was objective response rate by an independent review committee. The secondary end points were progression-free survival, overall survival (OS), disease control rate, safety, and so on. ResultsA total of 286 patients with EGFR T790M-positive advanced NSCLC were enrolled in this study, including 59 patients in part A (dose-verification study) and 227 patients in part B (second-line registration study). By data cutoff on September 17, 2021, the independent review committee–assessed objective response rate was 55.9% (95% confidence interval [CI]: 42.4–68.8) in part A and 60.4% (95% CI: 53.7–66.8) in part B. The median progression-free survival was 12.4 months (95% CI: 8.3–20.8) in part A and 12.6 months (95% CI: 9.7–15.3) in part B. The median OS was 26.0 months (95% CI: 23.3–not reached) in part A, and OS was immature in part B. Among the 286 patients, 44 of them experienced at least one grade 3 or higher treatment-related adverse event, with the most common ones as increased serum creatinine phosphokinase level (13 [4.5%]), diarrhea (six [2.1%]), and prolonged QT interval (three [1.0%]). Treatment-related skin rash was reported in 26 patients (9.1%), all grade 1 or 2. There was no interstitial lung disease reported in this study. ConclusionsSH-1028 is efficacious and tolerable in second-line treatment of patients with advanced NSCLC with positive EGFR T790M.

A Ten-Year Experience of Treating Chronic Myeloid Leukemia in Rural Rwanda: Outcomes and Insights for a Changing Landscape.

In describing our ten-year experience with treating chronic myeloid leukemia (CML) as part of the Glivec Patient Assistance Program (GIPAP) in rural Rwanda, we evaluate (1) patient characteristics and treatment outcomes, (2) resource-adapted management strategies, and (3) the impact of diagnostic capacity development. We retrospectively reviewed all patients with BCR-ABL-positive CML enrolled in this GIPAP program between 2009 and 2018. Clinical data were analyzed using descriptive statistics, Kaplan-Meier methods, proportional hazards regression, and the Kruskal-Wallis test. One hundred twenty-four patients were included. The median age at diagnosis was 34 (range 8-81) years. On imatinib, 91% achieved complete hematologic response (CHR) after a median of 49 days. Seven (6%) and 12 (11%) patients had primary and secondary imatinib resistance, respectively. The 3-year overall survival was 80% (95% CI, 72 to 87) for the cohort, with superior survival in imatinib responders compared with those with primary and secondary resistance. The median time from imatinib initiation to CHR was 59 versus 38 days (P = .040) before and after in-country diagnostic testing, whereas the median time to diagnosis (P = .056) and imatinib initiation (P = .170) was not significantly different. Coupling molecular diagnostics with affordable access to imatinib within a comprehensive cancer care delivery program is a successful long-term strategy to treat CML in resource-constrained settings. Our patients are younger and have higher rates of imatinib resistance compared with historic cohorts in high-income countries. High imatinib resistance rates highlight the need for access to molecular monitoring, resistance testing, and second-generation tyrosine kinase inhibitors, as well as systems to support drug adherence. Hematologic response is an accurate resource-adapted predictor of survival in this setting. Local diagnostic capacity development has allowed for continuous, timely CML care delivery in Rwanda.

Induction–maintenance approach for the chronic phase of chronic myeloid leukaemia (IMPACT-I): a prospective, single-arm, phase 2 study

Imatinib and second-generation tyrosine-kinase inhibitors (2G-TKIs) are standard options for the first-line treatment of chronic myeloid leukaemia. Although 2G-TKIs are superior to imatinib in terms of rate and depth of molecular response, they do not bring significant improvements in survival outcomes, and concerns exist over their long-term safety. The availability of a generic formulation makes imatinib an attractive economical option. We propose a novel induction-maintenance approach that would have the advantage of inducing early molecular response with 2G-TKIs, followed by maintenance with the safer and more affordable imatinib. IMPACT-I was a prospective, single-arm, phase 2 study done at Queen Mary Hospital, a university-affiliated tertiary hospital in Hong Kong. Adult patients with chronic myeloid leukaemia in chronic phase were enrolled after providing written informed consent. Inclusion criteria were having received a 2G-TKI as a first-line treatment for at least 12 months, and to have had a sustained and good molecular response (defined as a BCR-ABL1 level of ≤0·1%) for at least 6 months. Patients who had documented mutations in the kinase domain or a history of switching tyrosine-kinase inhibitors due to unsatisfactory responses were excluded. After switching to imatinib, participants were followed up for clinical, haematological, and molecular monitoring (bimonthly in the first 6 months, quarterly in months 7-12; and every 3-6 months thereafter, with follow-up ongoing at the time of writing). Molecular response was assessed according to the International Scale as the ratio of BCR-ABL1 transcripts to ABL1 transcripts with an assay sensitivity of molecular response of at least 4·5 (MR4·5) at least. Molecular tests were repeated at 1-month intervals if BCR-ABL1 was higher than 0·1% but less than 1%. Molecular progression was defined as BCR-ABL1 of at least 1% at one timepoint, or BCR-ABL1 higher than one 0·1% but less than 1% in two consecutive tests. The primary outcome was molecular progression-free survival at 6 months after switching to imatinib. Ten patients were enrolled between Aug 9, 2017, and April 27, 2021. Six patients had had dasatinib for at least 12 months, and four patients had had nilotinib for at least 12 months. The median duration of 2G-TKI treatment before the switch was 42·5 months (IQR 32·5-52·5) and the median durations of good molecular response before the switch was 30·0 months (IQR 19·5-41·5). All except one patient (on the nilotinib group) had adverse reactions of grades 1-3 on the Common Terminology Criteria for Adverse Events (CTCAE) to 2G-TKIs, with rash (two in the nilotinib group, two in the dasatinib group) and pleural effusion (none in the nilotinib group, three in the dasatinib group) being the most common. After a median follow-up of 41·0 months (IQR 11·0-50·6), all ten patients continued to have good molecular response. Molecular progression-free survival at 6 months was 100%. One patient, who was in molecular response 3 before withdrawal, exited the trial after 9 months of imatinib therapy for personal reasons. The other nine patients remained on generic imatinib as of the last follow-up on Dec 22, 2021; eight (89%) of nine were in deep molecular response (MR4·5 or greater). Imatinib was well tolerated. Only grade 1-2 toxic effects were observed, namely peripheral oedema, diarrhoea, and dyspepsia. Our study suggests that the induction-maintenance approach is safe and efficacious. All patients remain in good molecular response after switching to imatinib, and the vast majority of them had a deep molecular response. This practical strategy not only implies substantial pecuniary savings (estimated at US$30 000 per annum per patient), but also retains the possibility of treatment-free remission, bringing important and positive health-cost implications for low-income regions. 2017 Young Investigator Research Grant from the Hong Kong College of Physicians.

The EGFR-STYK1-FGF1 axis sustains functional drug tolerance to EGFR inhibitors in EGFR-mutant non-small cell lung cancer

Non-small cell lung cancer (NSCLC) patients harboring activating mutations in epidermal growth factor receptor (EGFR) are sensitive to therapy with EGFR tyrosine kinase inhibitors (TKI). Despite remarkable clinical responses using EGFR TKI, surviving drug tolerant cells serve as a reservoir from which drug resistant tumors may emerge. This study addresses the need for improved efficacy of EGFR TKI by identifying targets involved in functional drug tolerance against them. To this aim, a high-throughput siRNA kinome screen was performed using two EGFR TKI-sensitive EGFR-mutant NSCLC cell lines in the presence/absence of the second-generation EGFR TKI afatinib. From the screen, Serine/Threonine/Tyrosine Kinase 1 (STYK1) was identified as a target that when downregulated potentiates the effects of EGFR inhibition in vitro. We found that chemical inhibition of EGFR combined with the siRNA-mediated knockdown of STYK1 led to a significant decrease in cancer cell viability and anchorage-independent cell growth. Further, we show that STYK1 selectively interacts with mutant EGFR and that the interaction is disrupted upon EGFR inhibition. Finally, we identified fibroblast growth factor 1 (FGF1) as a downstream effector of STYK1 in NSCLC cells. Accordingly, downregulation of STYK1 counteracted the afatinib-induced upregulation of FGF1. Altogether, we unveil STYK1 as a valuable target to repress the pool of surviving drug tolerant cells arising upon EGFR inhibition. Co-targeting of EGFR and STYK1 could lead to a better overall outcome for NSCLC patients.

P722: IS THE SECOND-GENERATION TYROSINE KINASE INHIBITOR A BETTER THERAPY THAN IMATINIB FOR PERSONS WITH CHRONIC MYELOID LEUKEMIA PRESENTING IN ACCELERATED-PHASE?

Background: Although most patients with chronic myeloid leukemia (CML) were presenting in the chronic phase at diagnosis, approximately 5% presented with features of accelerated phase. The features of accelerated phase were variably defined by different criteria, such as MD Anderson and European LeukemiaNet (ELN) criteria most often used. Regardless of these criteria used to defined accelerated phase, only scant data were available regarding the prognostic co-variates for outcome. Moreover, evidence that patients could benefit more from the second generation (2G-) tyrosine kinase inhibitor (TKI) than imatinib as initial therapy was still extremely limited. Aims: Explore whether patients with chronic myeloid leukemia (CML) presenting in accelerated-phase could benefit from initial second-generation tyrosine kinase inhibitor (2G-TKI) therapy. Methods: We interrogated data from consecutive patients with CML presenting in accelerated phase at diagnosis by the MD Anderson criteria (n = 325) or ELN criteria (n = 275). Propensity score matching (PSM) analysis was used to compare cytogenetic and molecular responses and outcomes in those receiving initial imatinib versus a 2G-TKI. COX multi-variable regression model was performed to identify the prognostic co-variates. Results: In the cohort defined by MD Anderson criteria, PSM analysis showed that patients receiving initial 2G-TKI (n = 89) had higher probability of achieving a CCyR (p = 0.01), MMR (p = 0.04) and MR4.5 (p = 0.004) than those receiving imatinib (n = 156), however, probabilities of FFS, PFS and survival were similar. Multi-variable analyses showed that lower platelets and higher blasts in blood or bone marrow were significantly-associated with poor FFS, PFS and/or survival (Figure A). In an attempt to determine whether choice of therapy contributed to the differences in responses and outcomes, platelets < 600 × 10E+9/L and blood / bone marrow blasts ≥ 5% were identified as the prognostic categorical co-variates by ROC analyses. The entire cohort were classified into low- (possessing none of these co-variates, n = 57), intermediate (possessing any 1 of these co-variates, n = 127) or high-risk (possessing all of these co-variates, n = 61) subgroups. There were significant differences in probabilities of outcomes among these risk subgroups (all p values < 0.001, Figure B). In each risk subgroup, patients receiving initial 2G-TKI had the similar outcomes to those receiving imatinib except higher incidences of responses including CCyR, MMR and MR4.5. The same results were observed in the cohort defined by ELN criteria. Image:Summary/Conclusion: Initial 2G-TKI lead to similar outcomes as imatinib in patients with CML presenting in accelerated-phase except higher therapy responses.

Efficacy and Safety of Befotertinib (D-0316) in Patients With EGFR T790M-Mutated NSCLC That Had Progressed After Prior EGFR Tyrosine Kinase Inhibitor Therapy: A Phase 2, Multicenter, Single-Arm, Open-Label Study

IntroductionBefotertinib (D-0316) is a novel, third-generation EGFR tyrosine kinase inhibitor (TKI). This study evaluated befotertinib in patients with locally advanced or metastatic NSCLC who developed an EGFR T790M mutation after progression on first- or second-generation EGFR TKI therapy. MethodsThis was a single-arm, open-label, phase 2 study at 49 hospitals across mainland China. Patients with locally advanced or metastatic NSCLC harboring EGFR T790M mutations with disease progression after prior first- or second-generation EGFR TKI therapy received oral befotertinib of 50 mg (cohort A) or 75 to 100 mg (cohort B) once daily. The primary end point was objective response rate (ORR) assessed by an independent review committee in intention-to-treat population. This trial is registered with ClinicalTrials.gov, number NCT03861156. ResultsA total of 176 patients and 290 patients were included in cohorts A (50 mg) and B (75–100 mg), respectively. At data cutoff (August 15, 2021), independent review committee–assessed ORR was 67.6% (95% confidence interval [CI]: 61.9%–72.9%) in cohort B. The investigator-assessed ORR was 54.0% (95% CI: 46.3%–61.5%) in cohort A and 65.9% (95% CI: 60.1%–71.3%) in cohort B. The median investigator-assessed progression-free survival was 11.0 (95% CI: 9.6–12.5) months in cohort A and 12.5 (95% CI: 11.1–13.8) months in cohort B. The median independent review committee–assessed progression-free survival in cohort B was 16.6 (95% CI: 15.0–not evaluable [NE]) months. The intracranial ORR was 26.7% (95% CI: 7.8%–55.1%) in cohort A by investigator assessment, while 57.1% (95% CI: 34.0%–78.2%) and 55.9% (95% CI: 37.9%–72.8%) in cohort B by investigator and independent review committee assessment, respectively. The median investigator-assessed intracranial progression-free survival was 16.5 (95% CI: 8.6–NE) months in cohort A, while the median intracranial progression-free survival was not evaluable in cohort B due to immature data regardless of investigator or independent review committee assessment. and NE (95% CI: 13.8–NE) in cohort B. The overall survival was immature. Grade 3 or higher treatment-related adverse events and treatment-related serious adverse events occurred in 20.5% and 11.4% of patients in cohort A and in 29.3% and 10.0% of patients in cohort B, respectively. ConclusionsBefotertinib of 75 to 100 mg has satisfying efficacy and manageable toxicity in patients with locally advanced or metastatic NSCLC harboring T790M mutation with resistance to first- or second-generation EGFR TKIs. A phase 3 randomized trial is underway (NCT04206072).

Abstract CT184: Emerging evidence of activity of BLU-945 in patients with advanced EGFR-mutant NSCLC utilizing circulating tumor DNA (ctDNA) in the phase 1/2 SYMPHONY study

Abstract Background: Despite recent advances in the treatment of EGFR-mutant (EGFRm) non-small cell lung cancer (NSCLC), most patients treated with third-generation (3G) EGFR tyrosine kinase inhibitors (TKIs), such as osimertinib, experience disease progression. The most common on-target EGFR resistance mutation is at the EGFR C797 residue (i.e., C797S), which prevents covalent binding to 3G EGFR TKIs. While 3G TKIs are effective in patients with EGFR activating and T790M mutations (commonly seen post-progression after first-/second-generation TKIs), there are no targeted therapies approved after their failure. BLU-945 is an investigational, reversible, and selective next-generation EGFR TKI intended for use as a single agent or in combination with other agents to suppress activating and on-target resistance EGFR mutants, including T790M and C797S, while sparing wildtype (wt) EGFR. BLU-945 has shown in vivo antitumor activity in 3G EGFR TKI-naïve as well as resistant NSCLC patient-derived xenograft models with EGFR T790M and C797S mutations. Based on this, we started SYMPHONY (NCT04862780), a phase 1/2 study in patients with metastatic EGFRm NSCLC, to determine the maximum tolerated dose and/or the recommended phase 2 dose (RP2D); and to assess the safety, pharmacokinetics (PK), and antitumor activity of BLU-945. Methods: In the ongoing phase 1 dose-escalation part of the study, patients aged ≥18 years with metastatic EGFRm NSCLC previously treated with ≥1 EGFR TKI (Eastern Cooperative Oncology Group performance status of 0-2) received BLU-945 once daily (QD) on a 28-day cycle following a Bayesian Optimal Interval escalation design. Adverse events (AEs), dose-limiting toxicities (DLTs), PK, ctDNA (in real-time using FoundationOne Liquid panel), and radiographic antitumor activity (by RECIST 1.1 criteria) were assessed in the first 4 treatment cohorts. Results: As of the January 7, 2022, data cut, 18 patients have been treated with BLU-945 at 25-200 mg QD. Of these, 14 (77.8%) patients had received ≥2 lines of prior systemic anticancer therapy in the metastatic setting. There were no DLTs, and most AEs were low grade. Treatment-related AEs (all Grade 1) occurred in 8 (44.4%) patients with the most common being nausea (n=3). EGFR mutation allele fraction assessment by ctDNA at C1D1 and C1D15 showed that tumors were heterogeneous at baseline. At doses of 50 mg QD and higher, reductions in EGFR resistance mutation allele fraction were seen in all patients (n=3) with EGFR C797S (n=2) and/or T790M (n=3) resistance mutations, with a median 48% reduction of these mutations. 50% of patients remain on treatment and dose escalation continues to determine the RP2D. Conclusion: As of the data cut, BLU-945 was generally well tolerated in heavily pre-treated patients with EGFRm NSCLC. There was also early evidence of a reduction in EGFR mutation allele fractions by ctDNA. Citation Format: Elaine Shum, Yasir Elamin, Karen L. Reckamp, Zofia Piotrowska, Julia Rotow, Daniel S. Tan, Koichi Goto, Jagan Parepally, Faris Albayya, Melinda Louie-Gao, Renata Sawtell, Alena Zalutskaya, David Spigel. Emerging evidence of activity of BLU-945 in patients with advanced EGFR-mutant NSCLC utilizing circulating tumor DNA (ctDNA) in the phase 1/2 SYMPHONY study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT184.

Abstract 1125: Elucidating the transcriptomic response to EGFR-targeted therapy in EGFR-driven glioblastoma

Abstract Glioblastoma (GBM) is the most common malignant brain tumor in adults with a dismal 15-month median survival. Standard therapy consisting of surgical resection, radiation, and temozolomide has been unsuccessful in meaningfully extending survival and preventing recurrence; thus, novel therapeutics are urgently needed. One proposed targeted treatment strategy for GBM involves using small molecule inhibitors against common genetic mutations. Epidermal growth factor receptor (EGFR) is the most commonly overexpressed oncogene in GBM (~56%). While EGFR tyrosine kinase inhibitors (TKI) have shown promise in other cancers, GBM clinical trials with EGFR TKI have failed. One reason for this failure is the development of adaptive therapeutic resistance. Understanding the mechanisms behind drug resistance is essential for the development of novel, effective therapeutics for GBM. To better understand adaptive resistance in GBM, we utilized two genetically engineered mouse astrocyte lines harboring common GBM mutations: Cdkn2a-/-, EGFRvIII (CEv3) and Cdkn2a-/-, Pten-/-, EGFRvIII (CEV3P). CDKN2A and PTEN are commonly deleted or otherwise inactivated tumor suppressor genes in GBM while the vIII variant of EGFR is the single most common oncogene mutation, making it an attractive therapeutic target. Cell lines CEv3 and CEv3P are both sensitive to neratinib, an irreversible second-generation EGFR TKI, at IC50 of 0.24μM and 0.13µM, respectively. To better understand adaptive response to neratinib treatment, we profiled the transcriptome with RNA sequencing at 0, 4, 24, and 48 hours. Our data shows that kinome rewiring is detectable after just 4 hours of treatment and sustained through 48 hours, with differential expression of 70% or more of the expressed kinome. We propose that differentially expressed kinases in response to neratinib can potentially activate alternative signaling pathways that bypass EGFR inhibition, which ultimately confers resistance to EGFR targeted therapy. Furthermore, we hypothesize that the epigenome is directly responsible for this adaptive kinome response through BRD4 dependent enhancer remodeling. Because dual therapy against EGFR and BRD4 has shown promising results in other cancers, targeting the epigenome through BRD4 represents a potential combination therapy with EGFR TKI in GBM. To profile BRD4-associated epigenomic changes, we used Cleavage Under Targets and Release Using Nuclease (CUT&amp;RUN) to interrogate several regulatory marks (H3K4me1, K3K4me3, H3K27ac) in addition to BRD4. We seek to integrate RNA sequencing and CUT&amp;RUN data to determine if kinases differentially expressed following neratinib treatment correlate with epigenetic marks for their respective enhancer(s). This work will provide insight into the adaptive resistance mechanism of EGFR driven GBM. Citation Format: Benjamin Lin, Julia Ziebro, Kasey R. Skinner, Abigail Shelton, Erin Smithberger, Ryan Bash, Frank B. Furnari, Ryan Miller. Elucidating the transcriptomic response to EGFR-targeted therapy in EGFR-driven glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1125.

Efficacy and Safety of Limertinib (ASK120067) in Patients With Locally Advanced or Metastatic EGFR Thr790Met-Mutated NSCLC: A Multicenter, Single-Arm, Phase 2b Study

IntroductionLimertinib (ASK120067) is a newly developed third-generation EGFR tyrosine kinase inhibitor targeting both sensitizing EGFR and EGFR Thr790Met (T790M) mutations. This study aimed to evaluate the efficacy and safety of limertinib in patients with locally advanced or metastatic EGFR T790M-mutated NSCLC. MethodsThis is a single-arm, open-label, phase 2b study conducted at 62 hospitals across the People’s Republic of China. Patients with locally advanced or metastatic NSCLC with centrally confirmed EGFR T790M mutations in tumor tissue or blood plasma who progressed after first- or second-generation EGFR tyrosine kinase inhibitors or with primary EGFR T790M mutations were enrolled. Patients received limertinib 160 mg orally twice daily until disease progression or unacceptable toxicity. The primary end point was objective response rate (ORR) assessed by independent review committee per the Response Evaluation Criteria in Solid Tumors version 1.1. Secondary end points included disease control rate, progression-free survival (PFS), duration of response (DoR), overall survival, and safety. Safety was assessed according to the National Cancer Institute Common Terminology Criteria for Adverse Events version 4.03. ResultsFrom July 16, 2019, to March 10, 2021, a total of 301 patients were enrolled and started the treatment of limertinib. All patients entered the full analysis set and safety set. By the data cutoff date on September 9, 2021, 76 (25.2%) remained on treatment. The median follow-up time was 10.4 months (range: 0.3–26.3). On the basis of full analysis set, the independent review committee-assessed ORR was 68.8% (95% confidence interval [CI]: 63.2%–74.0%) and disease control rate was 92.4% (95% CI: 88.8%–95.1%). The median PFS was 11.0 months (95% CI: 9.7–12.4), median DoR was 11.1 months (95% CI: 9.6–13.8), and median OS was not reached (95% CI 19.7 months–not evaluable). Objective responses were achieved across all prespecified subgroups. For 99 patients (32.9%) with central nervous system (CNS) metastases, the ORR was 64.6% (95% CI: 54.4%–74.0%), median PFS was 9.7 months (95% CI: 5.9–11.6), and median DoR was 9.6 months (95% CI: 8.1–15.2). For 41 patients who had assessable CNS lesion, the confirmed CNS-ORR was 56.1% (95% CI: 39.7%–71.5%) and median CNS-PFS was 10.6 months (95% CI: 5.6–not evaluable). In safety set, 289 patients (96.0%) experienced at least one treatment-related adverse event (TRAE), with the most common being diarrhea (81.7%), anemia (32.6%), rash (29.9%), and anorexia (28.2%). Grade ≥3 TRAEs occurred in 104 patients (34.6%), with the most common including diarrhea (13.0%), hypokalemia (4.3%), anemia (4.0%), and rash (3.3%). TRAEs leading to dose interruption and dose discontinuation occurred in 24.6% and 2% of patients, respectively. No TRAE leading to death occurred. ConclusionsLimertinib (ASK120067) was found to have promising efficacy and an acceptable safety profile for the treatment of patients with locally advanced or metastatic EGFR T790M-mutated NSCLC. Clinical Trial information: NCT03502850.

LUNG CANCER METASTASES IN THE BRAIN: MAJOR RESPONSE WITH AFATINIB

TYPE: Late Breaking Abstract TOPIC: Lung Cancer INTRODUCTION: Lung cancer (LC) is the leading cause of cancer-related death worldwide and it is responsible for nearly 50% of brain metastasis (BM) cases. Afatinib is a second-generation irreversible EGFR tyrosine kinase inhibitor, indicated in the treatment of metastatic LC with activating EGFR mutations. CASE PRESENTATION: A 71-year-old woman, ECOG PS 1, was diagnosed with stage IVb LC (T3N0M1b), EGFR mutated (exon 18: Glu790Lys, Lys744Asn, Gly719Ser). Staging brain MRI showed 2 left brain lesions, suggestive of BM, not surgically approachable: one in the parietal region (20x16mm) and another (3mm) in the temporo-occipital transition. In the Multidisciplinary Tumor Board was decided treatment with afatinib and stereotactic brain surgery (SBS). To plan SBS another brain MRI was performed showing a significant reduction of the left parietal lesion (10x8mm; figure 1) and complete disappearance of the other lesion, after 8 days of treatment, and SBS was canceled. Reevaluation after 3 months revealed partial imaging response on the lung and brain (BM with 9mm, major axis). Due to grade 2-3 skin rash and paronychia, the treatment dose was reduced until 20mg/day, with good tolerance. DISCUSSION: Despite having incomplete blood-brain barrier penetration, afatinib has the potential to treat LC BM, with a reported intracranial response rate ranging from 35%-72.9%. This efficacy was demonstrated in this case report, allowing brain radiation sparing strategy. CONCLUSIONS: This case report shows the effectiveness of afatinib in BM from EGFR mutated lung adenocarcinoma. DISCLOSURE: No significant relationships. KEYWORD: Brain metastases

Real-world analysis of the EGFR mutation detection in plasma ctDNA from patients with non-small cell lung cancer.

e21069 Background: Plasma sample has emerged as a promising surrogate sample for EGFR mutation detection in advanced non-small cell lung cancer (NSCLC). In clinical practice, whether EGFR variants in pretreatment plasma ctDNA of advanced lung cancer can predict prognosis in addition to guiding targeted therapy remains to be further explored. Methods: In this study, we retrospectively enrolled 315 NSCLC patients from Beijing Chest Hospital, 94.9% of whom were in stage IIIB-IV. EGFR gene mutation data from tissue detected by ARMS-PCR (Amoy Diagnostics, Xiamen, China) and paired plasma samples within one month of admission detected by SuperARMS-PCR (Amoy Diagnostics, Xiamen, China) were collected. The patients’ clinicopathological characteristics and treatment information were also collected for further analysis. Differences in PFS of targeted therapy between patients with positive and negative pretreatment plasma ctDNA EGFR mutation were compared. Results: EGFR-positive rate of tissue and plasma ctDNA was 65.1% (205/315) and 43.8% (138/315), respectively. L858R, 19-DEL, T790M, G719X, 20-INS, and L861Q mutations were detected in both samples. The sensitivity, specificity, PPV, NPV and concordance of ctDNA detection was 65.4%,96.4%, 97.1%, 59.9%, and 76.2%, respectively. In the study, patients’ pathological subtype was the factor affected plasma ctDNA EGFR alteration detection accuracy. The concordance in adenocarcinoma patients was obviously higher than that in non-adenocarcinoma (p = 0.02). 92 treatment naïve advanced patients with tissue EGFR mutation were received first and second-generation EGFR tyrosine kinase inhibitors (TKIs) therapies. 59.8% (55/92) patients also had EGFR mutation in plasma ctDNA, 40.2% (37/92) patients had no detectable EGFR mutations in plasma ctDNA. The median PFS in plasma ctDNA EGFR positive patients was 7.0 months versus 14.0 month in plasma ctDNA EGFR negative patients, with significantly difference (p = 0.004). Conclusions: Plasma sample could be a surrogate sample for molecular test when tissue sample was unavailable. The poor prognosis was observed in treatment naïve advanced NSCLC patients with baseline plasma EGFR mutation.