Small Molecule EGFR Inhibitors Research Articles

LOOP: An observational, prospective, multicenter study of patients with non-small cell lung cancer in the US receiving standard-of-care and initiating an approved therapy with risk of pneumonitis/ILD.

TPS12157 Background: A wide range of oncology treatments are associated with a risk of pneumonitis or ILD, which is an uncommon but serious side effect with potential for significant morbidity and mortality (Conte et al 2022). The development of pneumonitis/ILD remains unpredictable and relatively uncommon in a single practice or hospital setting. Risk of drug-induced pneumonitis/ILD remains a limiting factor to prescribing life-saving treatments. A non-invasive, patient-centric multimodal solution for remote data capture could support recognition and tracking of pulmonary symptoms in addition to providing insight for the clinical team to personalize the monitoring of patients according to their medical history or specific physiological markers. Methods: LOOP is an observational, prospective, multicenter study conducted in the US. Stage III and IV NSCLC patients receiving SoC and initiating treatment with an FDA-approved ICI (alone or in combination with other agents), ADC, or small molecule EGFR inhibitor are eligible to participate. The primary objective is to enable the development and refinement of an algorithm including documentation of its performance (specificity, sensitivity and odd ratio to inform risk of pulmonary/respiratory/thoracic-related events including ILD). A secondary objective proposes to characterize the risk factors, signs, and symptoms leading to onset, diagnosis, and treatment of pneumonitis/ILD in patients receiving SoC. The study will collect patient-generated data outside of point-of-care for six months, using questionnaires and a medical pulse-oximeter device . Clinical data available per SoC in the medical records will be collected. Approximately 600 patients will be enrolled over 13 months to accrue approximately 100 pneumonitis/ILD events. Events will include all grades of pneumonitis, including ILD and radiation pneumonitis, as determined by the Investigator. Qualitative interviews will be conducted to inform a more granular understanding of the patient specific experience of developing ILD. Logistic regression, area under curve, descriptive statistics and relevant visualizations will map the relationship between pneumonitis/ILD and patient’s health status. The study is currently enrolling; the protocol was approved by a central IRB. Clinical trial information: NCT06192004 .

CTNI-03. EFFICACY OF WSD0922-FU IN OSIMERTINIB-RESISTANT NSCLC WITH CENTRAL NERVOUS SYSTEM (CNS) METASTASES – UPDATES FROM THE DOSE ESCALATION COHORT OF A FIRST-IN-HUMAN PHASE 1 CLINICAL TRIAL (MC1914)

Abstract WSD0922-Fu is an oral, CNS-penetrant, small molecule EGFR inhibitor which potently inhibits EGFR aberrations specific to non-small cell lung cancer (NSCLC) and high-grade astrocytoma (HGA). MC1914 (NCT04197934) is a first-in-human phase 1 trial in patients with EGFR aberrant recurrent HGA and NSCLC. Adult patients with either recurrent EGFR mutant NSCLC with CNS metastases or recurrent EGFR aberrant HGA were enrolled and treated across six cohorts (40 mg once daily to 320 mg twice daily, 28-day cycles) to determine the maximum tolerated dose (MTD). 25 patients (17 HGA, 8 NSCLC) were enrolled (median age = 57 years; 24% female; 36% ECOG 0). All patients with HGA received prior radiation and temozolomide. All patients with NSCLC had previous disease progression on EGFR inhibitor therapy (prior osimertinib 88%). The median duration of WSD0922-Fu exposure among all patients was 55 days (range 3 to >279 days) [NSCLC median = 131 days; HGA median = 51 days]. Common treatment-related adverse events are comparable to other EGFR inhibitors (fatigue, acneiform rash, diarrhea, nausea, pruritis). At Cycle 1 Day 15 for patients treated at MTD (160 mg twice daily), the mean terminal elimination half-life (%CV) in the plasma was 31.6 h (102%) (median 14.5 h). The mean Cmax, Tmax, oral clearance at steady state, and AUC (0-12 h) (%CV) were 4513 ng/mL (50%), 2.0 hr (69%), 6.9 L/hr/m2 (42%), and 28084 h*ng/mL (52%), respectively. Among patients with NSCLC treated at MTD or higher dose levels and with available response data, 100% (5/5) of patients demonstrated clinical benefit (SD + PR) while 60% of patients had partial responses. Intracranial and extracranial efficacy was concordant. Furthermore, prolonged stable disease (9 cycles) was observed in a patient with EGFRvIII mutant GBM. Expansion cohorts are in progress to optimize WSD0922-Fu dose and schedule for future phase 2 development.

Radiotherapy Plus Cisplatin With or Without Lapatinib for Non–Human Papillomavirus Head and Neck Carcinoma

Patients with locally advanced non-human papillomavirus (HPV) head and neck cancer (HNC) carry an unfavorable prognosis. Chemoradiotherapy (CRT) with cisplatin or anti-epidermal growth factor receptor (EGFR) antibody improves overall survival (OS) of patients with stage III to IV HNC, and preclinical data suggest that a small-molecule tyrosine kinase inhibitor dual EGFR and ERBB2 (formerly HER2 or HER2/neu) inhibitor may be more effective than anti-EGFR antibody therapy in HNC. To examine whether adding lapatinib, a dual EGFR and HER2 inhibitor, to radiation plus cisplatin for frontline therapy of stage III to IV non-HPV HNC improves progression-free survival (PFS). This multicenter, phase 2, double-blind, placebo-controlled randomized clinical trial enrolled 142 patients with stage III to IV carcinoma of the oropharynx (p16 negative), larynx, and hypopharynx with a Zubrod performance status of 0 to 1 who met predefined blood chemistry criteria from October 18, 2012, to April 18, 2017 (median follow-up, 4.1 years). Data analysis was performed from December 1, 2020, to December 4, 2020. Patients were randomized (1:1) to 70 Gy (6 weeks) plus 2 cycles of cisplatin (every 3 weeks) plus either 1500 mg per day of lapatinib (CRT plus lapatinib) or placebo (CRT plus placebo). The primary end point was PFS, with 69 events required. Progression-free survival rates between arms for all randomized patients were compared by 1-sided log-rank test. Secondary end points included OS. Of the 142 patients enrolled, 127 (median [IQR] age, 58 [53-63] years; 98 [77.2%] male) were randomized; 63 to CRT plus lapatinib and 64 to CRT plus placebo. Final analysis did not suggest improvement in PFS (hazard ratio, 0.91; 95% CI, 0.56-1.46; P = .34) or OS (hazard ratio, 1.06; 95% CI, 0.61-1.86; P = .58) with the addition of lapatinib. There were no significant differences in grade 3 to 4 acute adverse event rates (83.3% [95% CI, 73.9%-92.8%] with CRT plus lapatinib vs 79.7% [95% CI, 69.4%-89.9%] with CRT plus placebo; P = .64) or late adverse event rates (44.4% [95% CI, 30.2%-57.8%] with CRT plus lapatinib vs 40.8% [95% CI, 27.1%-54.6%] with CRT plus placebo; P = .84). In this randomized clinical trial, dual EGFR-ERBB2 inhibition with lapatinib did not appear to enhance the benefit of CRT. Although the results of this trial indicate that accrual to a non-HPV HNC-specific trial is feasible, new strategies must be investigated to improve the outcome for this population with a poor prognosis. ClinicalTrials.gov Identifier: NCT01711658.

Menin Maintains Cholesterol Content in Colorectal Cancer via Repression of LXR-Mediated Transcription.

Menin is a nuclear scaffold protein that regulates gene transcription in an oftentimes tissue-specific manner. Our previous work showed that menin is over-expressed in colorectal cancer (CRC); however, the full spectrum of menin function in colonic neoplasia remains unclear. Herein, we aimed to uncover novel menin-regulated pathways important for colorectal carcinogenesis. RNA-Seq analysis identified that menin regulates LXR-target gene expressions in CRC cell lines. Isolated colonic epithelium from Men1f/f;Vil1-Cre and Men1f/f mice was used to validate the results in vivo. Cholesterol content was quantified via an enzymatic assay. RNA-Seq analysis in the HT-29 CRC cell line identified that menin inhibition upregulated LXR-target genes, specifically ABCG1 and ABCA1, with protein products that promote cellular cholesterol efflux. Similar results were noted across other CRC cell lines and with different methods of menin inhibition. Consistent with ABCG1 and ABCA1 upregulation, and similarly to LXR agonists, menin inhibition reduced the total cellular cholesterol in both HT-29 and HCT-15 cells. To confirm the effects of menin inhibition in vivo, we assessed Men1f/f;Vil1-Cre mice lacking menin expression in the colonic epithelium. Men1f/f;Vil1-Cre mice were found to have no distinct baseline phenotype compared to control Men1f/f mice. However, similarly to CRC cell lines, Men1f/f;Vil1-Cre mice showed an upregulation of Abcg1 and a reduction in total cellular cholesterol. Promoting cholesterol efflux, either via menin inhibition or LXR activation, was found to synergistically suppress CRC cell growth under cholesterol-depleted conditions and when administered concomitantly with small molecule EGFR inhibitors. Menin represses the transcription of LXR-target genes, including ABCA1 and ABCG1 in the colonic epithelium and CRC. Menin inhibition conversely upregulates LXR-target genes and reduces total cellular cholesterol, demonstrating that menin inhibition may be an important mechanism for targeting cholesterol-dependent pathways in colorectal carcinogenesis.

A novel EGFR inhibitor acts as potent tool for hypoxia-activated prodrug systems and exerts strong synergistic activity with VEGFR inhibition in vitro and in vivo

Small-molecule EGFR inhibitors have distinctly improved the overall survival especially in EGFR-mutated lung cancer. However, their use is often limited by severe adverse effects and rapid resistance development. To overcome these limitations, a hypoxia-activatable Co(III)-based prodrug (KP2334) was recently synthesized releasing the new EGFR inhibitor KP2187 in a highly tumor-specific manner only in hypoxic areas of the tumor. However, the chemical modifications in KP2187 necessary for cobalt chelation could potentially interfere with its EGFR-binding ability. Consequently, in this study, the biological activity and EGFR inhibition potential of KP2187 was compared to clinically approved EGFR inhibitors. In general, the activity as well as EGFR binding (shown in docking studies) was very similar to erlotinib and gefitinib (while other EGFR-inhibitory drugs behaved different) indicating no interference of the chelating moiety with the EGFR binding. Moreover, KP2187 significantly inhibited cancer cell proliferation as well as EGFR pathway activation in vitro and in vivo. Finally, KP2187 proved to be highly synergistic with VEGFR inhibitors such as sunitinib. This indicates that KP2187-releasing hypoxia-activated prodrug systems are promising candidates to overcome the clinically observed enhanced toxicity of EGFR-VEGFR inhibitor combination therapies.

Abstract CT102: Interim results of a first-in-human, dose escalation and expansion study of PLB-1004, an irreversible inhibitor of exon 20 insertion mutations in patients with non-small cell lung cancer

Abstract Background: PLB1004, a novel mono-anilino-pyrimidine small molecule inhibitor of EGFR, potently and irreversibly targets exon 20 insertion mutations with IC50 values ranging from 25.67-316.6 nM. The molecule also potently targets classical EGFR mutations ExDel19, L858R and T790M with a high degree of selectivity over wild-type EGFR. Methods: The study is a multi-center, open-label, dose escalation and expansion study conducted entirely in China, to assess the safety, tolerability, pharmacokinetics, and anti-tumor effect of PLB1004, administered orally once per day, in patients with advanced non-small cell lung cancer. The primary objective of the study is to assess the safety profile of PLB1004 and determine the RP2D of the molecule. Results: Dose escalation ranged from a starting dose of 10 mg QD to a top dose of 480 mg QD in 11 cohorts of patients. Dose expansion is ongoing at two dose levels, 320 mg QD and 400 mg QD. At the cutoff date for this abstract, July 31, 2022, a total of 65 patients (32 in escalation and 33 in expansion) had received treatment with PLB1004. The median age of the patients is 58 years old (range 31 to 77). Most patients are women (60%) with adenocarcinoma (95%) and good performance status (ECOG 0-1 in 90%). Prior therapy for NSCLC included platinum-based chemotherapy in 54% of patients and TKI therapy in 58%. Of note 58% of patients had intra-cranial metastases at baseline. The most frequent treatment related adverse events included diarrhea in 75% of patients (18% Grade 3), rash in 60% of patients (11% Grade 3), mouth ulceration in 43% of patients (1.5% Grade 3), elevated serum creatinine in 43% of patients (0% Grade 3) and elevated aspartate aminotransferase in 41% of patients (3% Grade 3). The criteria for DLT were not reported at any dose level and thus an MTD was not determined during cycle 1 of drug administration. Beyond Cycle 1, at the highest dose levels, frequent dose interruptions and reductions due to toxicity were observed, and further dose escalation was not attempted above 480 mg QD. A more complete summary of safety data will be presented at the meeting. Across all dose groups, a total of 38 subjects had EGFR Ex20ins mutations, including 29 at doses ≥ 160 mg QD, among whom 26 completed at least 1 tumor assessment. In these 26 patients the confirmed response rate was 57.7% (15/26) and the disease control rate (DCR) was 100% (26/26). Duration of response exceeded 6 months in 40% of responders. Conclusion: In the ongoing Phase 1 study, PLB1004 appears to be safe and well-tolerated with promising anti-tumor activity in patients with NSCLC harboring EGFR exon 20 insertion mutations. Citation Format: Jinji Yang, Yilong Wu, Meijuan Huang, Yanqiu Zhao, Jun Zhao, Jianying Zhou, Ying Mao, Huimin Wang, Yun Fan, David Chung, Kevin Schaab. Interim results of a first-in-human, dose escalation and expansion study of PLB-1004, an irreversible inhibitor of exon 20 insertion mutations in patients with non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT102.

Abstract 4016: Discovery of a small-molecule EGFR inhibitor that can potently target various EGFR mutants, including C797S mutant, in vitro and in vivo

Abstract EGFR is one of receptor tyrosine kinases (RTKs) and, upon ligand binding, turns on the downstream signals that include oncogenic RAS/MEK/ERK, PI3K/AKT/mTOR, and JAK/STAT pathways. EGFR gene mutations, such as Exon 19 deletion (Del19) and L858R mutations, induce abnormal activation of the EGFR protein even in the absence of the ligand leading to various cancers. EGFR mutations are found in non-small cell lung cancer (NSCLC) patients with 10-15% frequency (approximately 50% in Asian patients). Starting from Del19 and L8585R mutations, additional mutations in the EGFR gene occur during the treatment with 1st/2nd/3rd generation EGFR inhibitors, resulting in Del19/T790M, L858R/T790M, Del19/T790M/C797S, L858R/T790M/C797S, Del19/C797S, and L858R/C797S mutations. While double mutations that include the T790M mutation have been efficaciously treated with Osimertinib, there are currently no approved therapies that can effectively target the C797S-containing mutants. Here we present preclinical data showing a small-molecule inhibitor that effectively disables EGFR mutants, including Del19/T790M/C797S, L858R/T790M/C797S, Del19/C797S, and L858R/C797S mutants. High potency and selectivity were confirmed by in vitro kinase assays and cellular assays. Outstanding anti-cancer activity was observed in mouse xenograft models with various EGFR mutations and, importantly, it was inactive in the EGFR wild-type model. With confirmed brain penetrance through in vivo studies, our potent EGFR inhibitor may provide a great therapeutic potential for patients with EGFR mutation-driven NSCLC. Citation Format: Yeejin Jeon, Kiram Lee, Anna Jang, Miyeon Kim, Kyeong Jin Yoon, Yeri Lee, Dongsu Kim, Donggeon Kim, Dohyun Park, Sang Kyun Lim, Sung Pil Choi. Discovery of a small-molecule EGFR inhibitor that can potently target various EGFR mutants, including C797S mutant, in vitro and in vivo. [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 4016.

66 (PB056) - Anti-tumor activity of BDTX-1535, an irreversible CNS penetrant inhibitor of multiple EGFR extracellular domain alterations, in preclinical glioblastoma models

Background: EGFR genetic alterations, including mutation and amplification, are very common in glioblastoma multiforme (GBM), however, no targeted therapy has been approved for this disease. EGFR oncogenic mutations in GBM promote EGFR oncogenic covalent homodimer formation which leads to paradoxical activation and renders reversible inhibitors ineffective. An effective EGFR inhibitor in GBM must meet four conditions:1Highly potent and selective against a broad range of extracellular domain mutations and amplified EGFR,2Wild-type EGFR sparing,3Irreversible binding to circumvent paradoxical activation,4High CNS penetration. Our MAP discovery platform led to the identification of MasterKey inhibitor BDTX-1535, an irreversible 4th-generation CNS penetrant EGFR tyrosine kinase inhibitor (TKI) that potently and selectively targets a broad range of EGFR alterations in GBM. Materials and Methods: BDTX-1535 preclinical exposure was evaluated in multiple species in plasma and brain. Antitumor activity was assessed across a broad range of mouse PDX and allograft models, including an intracranial PDX. 2540 tumors were sequenced with the Tempus xT NGS assay. Mutational frequencies and co-expression status of oncogenic EGFR variants were assessed. The relationship between treatment history and oncogenic EGFR mutational frequency was analyzed. Results: BDTX-1535 is a small molecule that irreversibly inhibits a spectrum of EGFR alterations expressed in GBM together with EGFR amplification, while sparing inhibition of normally expressed wild type EGFR. BDTX-1535 avoids efficacy limiting paradoxical activation that can occur with reversible EGFR inhibitors. BDTX-1535 exhibits good oral bioavailability and a CNS Kpuu of 0.55 and 0.48 in rat and dog, respectively, comparing favorably with other CNS penetrant TKIs. Tumor regression and survival advantage were observed across all tumor models with EGFR amplification or mutation, including in an intracranial PDX model. EGFR mutations and amplification are commonly expressed in GBM. Consistent with published data, EGFR mutations, variants, and copy number gain were frequently co-expressed. For example, among tumors expressing EGFRvIII, ∼95% co-expressed at least one other variant, and among tumors expressing EGFRvVI, ∼45% co-expressed at least one other variant. Within a subset of GBM patients with longitudinal sequencing data, oncogenic EGFR mutations were expressed and persisted following front-line treatment. Conclusions: BDTX-1535 is a potent, CNS penetrant, irreversible small molecule EGFR inhibitor that shows efficacy against a broad range of extracellular domain mutations and EGFR amplification found in GBM patients. RWE findings demonstrate a heterogeneous EGFR mutational profile in GBM patients, with persistent prevalence over time. BDTX-1535 is currently in a phase I clinical study (NCT05256290). Conflict of interest: Ownership: Black Diamond Therapeutics Tempus Labs

1246P Multicenter phase Ib/II study of second-line varlitinib and paclitaxel in patients with EGFR/HER2 co-expressing advanced gastric cancer (K-MASTER-13)

Varlitinib is a small-molecule inhibitor of the tyrosine kinases EGFR, HER2, and HER4. We present a phase Ib/II study to evaluate the safety and efficacy of varlitinib in combination with weekly paclitaxel in EGFR/HER2 co-expressing advanced gastric cancer (AGC) patients. (KCT0003583). AGC patients who had failed 1st line fluoropyrimidine-containing chemotherapy, with evidence of both EGFR and HER2 overexpression by IHC (≥1+), were enrolled. Varlitinib [Dose 1: 300 mg BID, Dose -1: 300mg intermittent dose] and paclitaxel (80 mg/m2 D1,8,15) were investigated every 4 weeks. After determining the DLT and RP2D in phase Ib, phase II part was conducted to evaluate the anti-tumor activity with a primary endpoint of PFS. In the phase Ib study, 9 subjects were enrolled at the dose 1 level of varlitinib 300mg, of which 6 patients were evaluable for safety per protocol. Among the 6 evaluable patients, there was 1 DLT of Grade 4 AST/ALT elevation. The RP2D was varlitinib 300mg once daily combined with paclitaxel (80mg/m2 on days 1, 8, and 15). The median follow-up duration of 9.3 months [95% confidence interval (CI), 6.1-12.5]. Among 27 patients treated with RP2D including 5 subjects from Phase Ib, median PFS and OS were 4.1 (95% CI, 2.4-4.9 months) and 7.9 months (95% CI, 3.3-12.5 months), respectively. Among 16 patients with measurable disease and administered with RP2D, confirmed response and disease control was observed in 5 patients (ORR=31.3%) and 14 patients (DCR=87.5%), respectively. No definite association between EGFR or HER2 high expression and the efficacy of varlitinib and paclitaxel could be determined. Most common any grade of adverse events (AEs) were neutropenia (51.8% and 22.2% of Grade 3), diarrhea (27.3%), and AST/ALT elevation (22.2% and 11.1% of Grade 3). No treatment related death or unexpected AEs resulting in treatment cessation were observed with the RP2D. Varlitinib combined with paclitaxel revealed manageable toxicities and antitumor activity in patients with EGFR/HER2 co-expressing AGC who progressed after first-line chemotherapy. Updated outcomes for ongoing patients and biomarker analysis will be presented.

Phase 1/2 study of BLU-451, a central nervous system (CNS) penetrant, small molecule inhibitor of EGFR, in incurable advanced cancers with EGFR exon 20 insertion (ex20ins) mutations.

TPS9155 Background: Oncogenic EGFR ex20ins mutations, found in ̃2% of non-small cell lung cancers (NSCLC) and a small percentage of other cancers, are generally not responsive to EGFR-targeted agents that have been approved for treatment of NSCLC with a common EGFR mutation, including L858R and exon 19 deletion. Similar to these more common types of EGFR-mutated NSCLC, CNS metastases are a challenge with EGFR ex20ins NSCLC and are associated with poor outcomes. While two EGFR ex20ins-targeting drugs were recently approved by the FDA (amivantamab and mobocertinib), neither have established CNS activity. BLU-451 is a CNS penetrant, wild type-sparing, covalent small molecule inhibitor of EGFR ex20ins as well as atypical (G719C, G719S, L861Q) and common EGFR mutants. Preclinical data have shown BLU-451 to have potent antitumor activity, including in an intracranial xenograft model, which has led to its clinical development in EGFR-mutant NSCLC. Methods: BLU-451-1101 (NCT05241873) is a phase 1/2, global, open-label study designed to evaluate single-agent BLU-451 in patients with NSCLC harboring EGFR ex20ins that has progressed following prior treatment for incurable recurrent or metastatic disease. Patients with Eastern Cooperative Oncology Group performance status 0–1 and EGFR ex20ins, exon 18 G719X or exon 21 L861Q mutant NSCLC (phases 1 and 2) or other cancers except primary CNS tumors (phase 1 only) are eligible. Patients with known ROS, RAF, ALK, or EGFR C797S mutations will be excluded. Stable, asymptomatic brain metastases are permitted, and active asymptomatic brain metastases are permitted in specific cohorts. Primary endpoints are determination of maximum tolerated dose (MTD), recommended phase 2 dose (RP2D), safety and tolerability (phase 1), in addition to evaluation of antitumor activity at the RP2D by RECIST v1.1 (phase 2). Secondary endpoints are evaluation of pharmacokinetics (PK) and antitumor activity by RECIST v1.1.(phase 1) and PK, safety, tolerability, and CNS antitumor activity (phase 2). Dose escalation will utilize a 3+3 design with up to 6 patients per cohort in phase 1 dose escalation and up to 12 per cohort in phase 1 dose expansion. Phase 2 will enroll patients in 3 cohorts (n = 18 each): patients with prior platinum-based chemotherapy and an EGFR ex20ins-targeted agent; patients with prior platinum but no EGFR ex20ins-targeted agent; and patients with active asymptomatic brain metastases with prior platinum with or without an EGFR ex20ins-targeted agent. The study is planned for approximately 40 centers in North America, the Asia-Pacific region, and/or Europe. Clinical trial information: NCT05241873.

Mobocertinib (TAK-788): A Targeted Inhibitor of EGFR Exon 20 Insertion Mutants in Non-Small Cell Lung Cancer.

Most EGFR exon 20 insertion (EGFRex20ins) driver mutations in non-small cell lung cancer (NSCLC) are insensitive to approved EGFR tyrosine kinase inhibitors (TKI). To address the limitations of existing therapies targeting EGFR-mutated NSCLC, mobocertinib (TAK-788), a novel irreversible EGFR TKI, was specifically designed to potently inhibit oncogenic variants containing activating EGFRex20ins mutations with selectivity over wild-type EGFR. The in vitro and in vivo activity of mobocertinib was evaluated in engineered and patient-derived models harboring diverse EGFRex20ins mutations. Mobocertinib inhibited viability of various EGFRex20ins-driven cell lines more potently than approved EGFR TKIs and demonstrated in vivo antitumor efficacy in patient-derived xenografts and murine orthotopic models. These findings support the ongoing clinical development of mobocertinib for the treatment of EGFRex20ins-mutated NSCLC. SIGNIFICANCE: No oral EGFR-targeted therapies are approved for EGFR exon 20 insertion (EGFRex20ins) mutation-driven NSCLC. Mobocertinib is a novel small-molecule EGFR inhibitor specifically designed to target EGFRex20ins mutants. Preclinical data reported here support the clinical development of mobocertinib in patients with NSCLC with EGFR exon 20 insertion mutations.See related commentary by Pacheco, p. 1617.This article is highlighted in the In This Issue feature, p. 1601.

Menin-mediated Repression of Glycolysis in Combination with Autophagy Protects Colon Cancer Against Small-molecule EGFR Inhibitors.

Menin serves both tumor suppressor and promoter roles in a highly tumor-specific manner. In colorectal cancer, menin is overexpressed and plays a critical role in regulating transcription of SKP2, and combined treatment with a menin inhibitor and small-molecule EGFR inhibitor (EGFRi) leads to synergistic killing of colorectal cancer cells. However, the full spectrum of menin function in colorectal cancer remains uncertain. Herein, we demonstrate that menin inhibition increases glycolysis in colorectal cancer cells. This menin inhibitor-induced increase in glycolysis occurs in an mTOR-independent manner and enhances the sensitivity of colorectal cancer cells to EGFRis. In addition, we show that EGFRis induce autophagy in colorectal cancer cells, which is important for cell survival in the setting of combined treatment with an EGFRi and menin inhibitor. Inhibition of autophagy with chloroquine further sensitizes colorectal cancers to treatment with the combination of an EGFRi and menin inhibitor. Together, these findings uncover a novel role for menin in colorectal cancer as a repressor of glycolysis and demonstrate that menin inhibitor-induced increases in glycolysis sensitize colorectal cancer cells to EGFRis. In addition, these findings illustrate the importance of autophagy as a protective mechanism against EGFRis, especially in the presence of menin inhibition. Ultimately, these data open the possibility of using menin-mediated regulation of glycolysis to potentially improve treatment modalities for colorectal cancer.

Activation of epidermal growth factor receptor signaling mediates cellular senescence induced by certain pro-inflammatory cytokines.

It is well established that inflammation in the body promotes organism aging, and recent studies have attributed a similar effect to senescent cells. Considering that certain pro‐inflammatory cytokines can induce cellular senescence, systematically evaluating the effects of pro‐inflammatory cytokines in cellular senescence is an important and urgent scientific problem, especially given the ongoing surge in aging human populations. Treating IMR90 cells and HUVECs with pro‐inflammatory cytokines identified six factors able to efficiently induce cellular senescence. Of these senescence‐inducing cytokines, the activity of five (namely IL‐1β, IL‐13, MCP‐2, MIP‐3α, and SDF‐1α) was significantly inhibited by treatment with cetuximab (an antibody targeting epidermal growth factor receptor [EGFR]), gefitinib (a small molecule inhibitor of EGFR), and EGFR knockdown. In addition, treatment with one of the senescence‐inducing cytokines, SDF‐1α, significantly increased the phosphorylation levels of EGFR, as well as Erk1/2. These results suggested that pro‐inflammatory cytokines induce cellular senescence by activating EGFR signaling. Next, we found that EGF treatment could also induce cellular senescence of IMR90 cells and HUVECs. Mechanically, EGF induced cellular senescence via excessive activation of Ras and the Ras‐BRaf‐Erk1/2 signaling axis. Moreover, EGFR activation induced IMR90 cells to secrete certain senescence‐associated secretory phenotype factors (IL‐8 and MMP‐3). In summary, we report that certain pro‐inflammatory cytokines induce cellular senescence through activation of the EGFR‐Ras signaling pathway. Our study thus offers new insight into a long‐ignored mechanism by which EGFR could regulate cellular senescence and suggests that growth signals themselves may catalyze aging under certain conditions.

Chemogenomic Analysis of the Druggable Kinome and Its Application to Repositioning and Lead Identification Studies

Owing to the intrinsic polypharmacological nature of most small-molecule kinase inhibitors, there is a need for computational models that enable systematic exploration of the chemogenomic landscape underlying druggable kinome toward more efficient kinome-profiling strategies. We implemented VirtualKinomeProfiler, an efficient computational platform that captures distinct representations of chemical similarity space of the druggable kinome for various drug discovery endeavors. By using the computational platform, we profiled approximately 37 million compound-kinase pairs and made predictions for 151,708 compounds in terms of their repositioning and lead molecule potential, against 248 kinases simultaneously. Experimental testing with biochemical assays validated 51 of the predicted interactions, identifying 19 small-molecule inhibitors of EGFR, HCK, FLT1, and MSK1 protein kinases. The prediction model led to a 1.5-fold increase in precision and 2.8-fold decrease in false-discovery rate, when compared with traditional single-dose biochemical screening, which demonstrates its potential to drastically expedite the kinome-specific drug discovery process.

Combined Menin and EGFR Inhibitors Synergize to Suppress Colorectal Cancer via EGFR-Independent and Calcium-Mediated Repression of SKP2 Transcription.

Menin is a nuclear epigenetic regulator that can both promote and suppress tumor growth in a highly tissue-specific manner. The role of menin in colorectal cancer, however, remains unclear. Here, we demonstrate that menin was overexpressed in colorectal cancer and that inhibition of menin synergized with small-molecule inhibitors of EGFR (iEGFR) to suppress colorectal cancer cells and tumor xenografts in vivo in an EGFR-independent manner. Mechanistically, menin bound the promoter of SKP2, a pro-oncogenic gene crucial for colorectal cancer growth, and promoted its expression. Moreover, the iEGFR gefitinib activated endoplasmic reticulum calcium channel inositol trisphosphate receptor 3 (IP3R3)-mediated release of calcium, which directly bound menin. Combined inhibition of menin and iEGFR-induced calcium release synergistically suppressed menin-mediated expression of SKP2 and growth of colorectal cancer. Together, these findings uncover a molecular convergence of menin and the iEGFR-induced, IP3R3-mediated calcium release on SKP2 transcription and reveal opportunities to enhance iEGFR efficacy to improve treatments for colorectal cancer. SIGNIFICANCE: Menin acts as a calcium-responsive regulator of SKP2 expression, and small molecule EGFR inhibitors, which induce calcium release, synergize with Menin inhibition to reduce SKP2 expression and suppress colorectal cancer.

LncRNAs GIHCG and SPINT1-AS1 Are Crucial Factors for Pan-Cancer Cells Sensitivity to Lapatinib.

Lapatinib is a small molecule inhibitor of EGFR (HER1) and ERBB2 (HER2) receptors, which is used for treatment of advanced or metastatic breast cancer. To find the drug resistance mechanisms of treatment for EGFR/ERBB2 positive tumors, we analyzed the possible effects of lncRNAs. In this study, using CCLE (Cancer Cell Line Encyclopedia) database, we explored the relationship between the lncRNAs and Lapatinib sensitivity/resistance, and then validated those findings through in vitro experiments. We found that the expression of EGFR/ERBB2 and activation of ERBB pathway was significantly related to Lapatinib sensitivity. GO (Gene Oncology) analysis of top 10 pathways showed that the sensitivity of Lapatinib was positively correlated with cell keratin, epithelial differentiation, and cell-cell junction, while negatively correlated with signatures of extracellular matrix. Forty-four differentially expressed lncRNAs were found between the Lapatinib sensitive and resistant groups (fold-change > 1.5, P < 0.01). Gene set variation analysis (GSVA) was performed based on 44 lncRNAs and genes in the top 10 pathways. Five lncRNAs were identified as hub molecules. Co-expression network was constructed by more than five lncRNAs and 199 genes in the top 10 pathways, and three lncRNAs (GIHCG, SPINT1-AS1, and MAGI2-AS3) and 47 genes were identified as close-related molecules. The three lncRNAs in epithelium-derived cancers were differentially expressed between sensitive and resistant groups, but no significance was found in non-epithelium-derived cancer cells. Correlation analysis showed that SPINT1-AS1 (R = −0.715, P < 0.001) and GIHCG (R = 0.557, P = 0.013) were correlated with the IC50 of epithelium-derived cancer cells. In further experiments, GIHCG knockdown enhanced cancer cell susceptibility to Lapatinib, while high level of SPINT1-AS1 was a sensitive biomarker of NCI-N87 and MCF7 cancer cells to Lapatinib. In conclusions, lncRNAs GIHCG and SPINT1-AS1 were involved in regulating Lapatinib sensitivity. Up-regulation of GIHCG was a drug-resistant biomarker, while up-regulation of SPINT1-AS1 was a sensitive indicator.

Role of osimertinib in the treatment of EGFR-mutation positive non-small-cell lung cancer.

Mutations in the EGFR occur in approximately 10-35% of non-small-cell lung cancer (NSCLC) patients. Osimertinib is a third-generation oral small molecule inhibitor of EGFR, active against the common targetable activating EGFR mutations in L858R and exon 19 deletion; it also inhibits the T790M mutation. It was initially developed and approved for the treatment of acquired resistance to EGFR inhibition mediated by the T790M pathway activation. Recently, the FLAURA trial showed significantly improved progression-free survival with osimertinib compared with the first generation EGFR tyrosine kinase inhibitors gefitinib or erlotinib; this has led to its approval by US FDA and European Medicines Agency (EMA) as frontline therapy. Ongoing studies will define the resistance mechanisms to osimertinib, novel combination approaches and role in earlier stages of NSCLC.

Chemogenomic Analysis of the Druggable Kinome and Its Application to Repositioning and Lead Identification Studies

Due to the intrinsic polypharmacological nature of most small-molecule kinase inhibitors, there is a need for computational models that enable systematic exploration of the chemogenomic landscape underlying druggable kinome toward more efficient kinome profiling strategies. We implemented VirtualKinomeProfiler, an efficient computational platform that captures distinct representations of chemical similarity space of the druggable kinome for various drug discovery endeavors. By employing the computational platform, we profiled approximately 37 million compound-kinase pairs and made predictions for 151,708 compounds in terms of their repositioning and lead molecule potential against 248 kinases simultaneously. Experimental testing with biochemical assays validated 51 of the predicted interactions, identifying 19 small-molecule inhibitors of EGFR, HCK, FLT1, and MSK1 protein kinases. The prediction model led to a 1.5-fold increase in precision and 2.8-fold decrease in false discovery rate, when compared to traditional single-dose biochemical screening, which demonstrates its potential to drastically expedite the kinome-specific drug discovery process.

Highlights of This Issue

Obg-like ATPase 1 (OLA1) was identified as a protein that functions in centrosome regulation together with BRCA1. Yoshino and colleagues identified five missense mutants of OLA1 that are deficient in the regulation of centrosome number. Three of them did not bind to BARD1, a heterodimer partner of BRCA1. Two phosphomimetic mutations restored the binding to BARD1. A BARD1 mutant, reported in cancer, failed to bind to OLA1 and rescue the BARD1 knockdown-induced centrosome amplification. These findings demonstrate that the OLA1-BARD1 interaction is critical for the regulation of centrosome number. Thus, OLA1 is important for the genome integrity to prevent tumor development.Resistance to radiation therapy is a hallmark of glioblastoma multiforme (GBM). Radiation can induce ER stress and downstream signaling associated with the endoplasmic reticulum stress response (ERSR). Protein kinase R-like endoplasmic reticulum kinase (PERK) is one of the regulators of ERSR. The current Rapid Impact, investigates the significance of PERK in GBM after ionizing radiation (IR). It was determined that radiation enhanced PERK-eIF2α-ATF4 pathway in GBM, thereby influencing survival and death processes. The dual function of PERK as a mediator of survival and death provides multiple approaches to enhance the efficacy of radiation therapy.Development of resistance to small molecule EGFR inhibitors in non-small cell lung cancer (NSCLC) patients with activating EGFR mutations has limited the efficacy of such treatment. Though recent studies have deepened the understanding of the molecular mechanisms, fully understanding and overcoming the resistance is still a challenge. This study, by Lu and colleagues, demonstrates that hypoxia promotes resistance to gefitinib in NSCLC cells in a pathway linked to features of epithelial-to-mesenchymal transition (EMT) and dependent on the function of the histone lysine demethylases, LSD1 and PLU-1. The results provide the rationale for combining EGFR inhibitors with LSD1 inhibitors as a therapeutic strategy for NSCLC.Cholangiocarcinoma (CCA) is a rare tumor type with very limited treatment options. To identify new molecular susceptibilities, this study interrogated the Hippo signaling pathway and its effector protein YAP. In the models tested, YAP regulation was independent of the Hippo pathway and was driven by SRC family kinase-mediated tyrosine phosphorylation. Tyrosine phosphorylation lead to nuclear retention of YAP, a so-called nuclear retention signal. Subsequently, LCK was identified as the most potent mediator of YAP phosphorylation, a previously undescribed function for LCK. Finally, LCK-mediated YAP phosphorylation was found to be targetable in vivo, utilizing the pan-SFK inhibitor dasatinib.

Highlights of This Issue

Uckermann and colleagues use infrared spectroscopy and present a translational approach for fast, label-free optical analysis of the IDH1 genotype of human glioma. Based on the initial research performed on cell lines and tumor cryosections, fresh glioma biopsies were classified regarding their IDH1 genotype with an accuracy of 86%. Because IDH1 mutations are early events in glioma formation with prognostic impact and most likely dichotomizing therapeutic decision making, analysis of the tumor's spectrome might be exploited to complement histopathology and molecular pathology for an in situ diagnostic screen.Clinical utilization of circulating tumor cells (CTC) as a biomarker has been limited by the low sensitivity of CTC assays. Myung and colleagues demonstrate that CTC capture can be improved through two innovative concepts: biomimetic cell rolling and nanotechnology-enabled multivalent binding capture. The investigators show that the new assay can capture high numbers of CTCs in a diverse cohort of patients. Moreover, CTC change is correlated with treatment response and disease status. These findings hold potential for clinical translation.Both EGFR and VEGF are validated targets for treatment of patients with metastatic colorectal cancer (mCRC); however, combinations of monoclonal antibodies targeting both pathways show disappointing results. Mésange and colleagues show that combinations of bevacizumab and erlotinib, a small molecule EGFR inhibitor, have activity in CRC models independent of RAS status and bevacizumab resistance. The results provide a molecular framework to better understand the increased activity of the bevacizumab-erlotinib combination, compared with bevacizumab alone, in the GERCOR DREAM phase III clinical trial. Differential activity of mAb and TKI targeting the same signaling pathway is likely applicable for other tumor types.Attempts at treating glioblastoma (GBM) patients with checkpoint inhibitors have failed to provide a survival benefit. A potential mechanism explaining the failure of PD-1 blockade is based on work showing that GBM-infiltrating T cells increase immunosuppressive indoleamine 2,3 dioxygenase 1 (IDO1) levels. Ladomersky and colleagues tested IDO1 inhibitor and PD-1 mAb treatment, with or without radiotherapy, and found that the combination of all three agents led to long-term survival in a substantial fraction of mice with intracranial GBM. These data provide rationale for the soon-to-open phase I/IIa clinical trial of simultaneous radiotherapy with PD-1 and IDO1 inhibition in GBM patients.