Efficacy Of Osimertinib Research Articles

Abstract 7203: Anti-HDGF antibody attenuates the rise of resistance to EGFR tyrosine kinase inhibitor in NSCLC patient-derived xenograft tumors

Abstract Mutant epidermal growth factor receptor (EGFR), a major oncogenic driver in non-small cell lung cancer (NSCLC), is found in the tumors of 15% (western countries) to 50% (Asian countries) of patients. EGFR-targeted therapy using tyrosine kinase inhibitors (TKIs) is a standard of care for those patients who developed metastatic or recurrent diseases. However, despite having an 80% initial response rate, most patients had partial tumor regression and their disease would progress when acquired resistance emerges. Thus, developing more effective treatment is an unmet need. The clinical response of these patients can be recapitulated in mouse models of patient-derived xenograft (PDX) tumor bearing sensitizing EGFR mutations. In this study, treating established PDX tumors with osimertinib, a third generation EGFR TKI, induced partial tumor regression (50% to 70% size reduction from baseline) followed by progression with a median progression-free survival (PFS) of 26 to 28 days. Interestingly, co-administering an antibody against hepatoma-derived growth factor (HDGF) with osimertinib resulted in enhanced tumor regression (98% to 100% size reduction from baseline) which translated into significantly extended animal survival with a median PFS of 103 or 135 days. Immunohistochemical and western blot examination of tumors collected at different treatment timepoints indicated that AKT/mTOR and MAPK pathways were reactivated after initial suppression in TKI monotherapy arm despite persistent EGFR inhibition. Since AKT/mTOR and MAPK pathways are key survival and proliferative signaling pathways, their reactivation can promote TKI tolerance of tumor cells and the emergence of TKI resistance. However, blocking HDGF attenuated the reactivation of these pathways which could partially explain the enhanced efficacy of osimertinib plus anti-HDGF antibody combination treatment seen in this study. Our results suggest tumor-derived HDGF could play a crucial role in the rise of acquired resistance to osimertinib. Identifying the exact cells and molecular pathways utilized by HDGF to promote tumor cell tolerance to TKI will help us understand how TKI sensitive tumor cells survive EGFR blockade and emerge as resistant cells. Citation Format: Cindy Q. Zhou, Ariel Li, Kaoru Ri, Ahmed Sultan, Hening Ren. Anti-HDGF antibody attenuates the rise of resistance to EGFR tyrosine kinase inhibitor in NSCLC patient-derived xenograft tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7203.

DNA topoisomerase II inhibition potentiates osimertinib's therapeutic efficacy in EGFR-mutant non-small cell lung cancer models.

Development of effective strategies to manage the inevitable acquired resistance to osimertinib, a third-generation EGFR inhibitor for the treatment of EGFR-mutant (EGFRm) non-small cell lung cancer (NSCLC), is urgently needed. This study reports that DNA topoisomerase II (Topo II) inhibitors, doxorubicin and etoposide, synergistically decreased cell survival, with enhanced induction of DNA damage and apoptosis in osimertinib-resistant cells; suppressed the growth of osimertinib-resistant tumors; and delayed the emergence of osimertinib-acquired resistance. Mechanistically, osimertinib decreased Topo IIα levels in EGFRm NSCLC cells by facilitating FBXW7-mediated proteasomal degradation, resulting in induction of DNA damage; these effects were lost in osimertinib-resistant cell lines that possess elevated levels of Topo IIα. Increased Topo IIα levels were also detected in the majority of tissue samples from patients with NSCLC after relapse from EGFR tyrosine kinase inhibitor treatment. Enforced expression of an ectopic TOP2A gene in sensitive EGFRm NSCLC cells conferred resistance to osimertinib, whereas knockdown of TOP2A in osimertinib-resistant cell lines restored their susceptibility to osimertinib-induced DNA damage and apoptosis. Together, these results reveal an essential role of Topo IIα inhibition in mediating the therapeutic efficacy of osimertinib against EGFRm NSCLC, providing scientific rationale for targeting Topo II to manage acquired resistance to osimertinib.

Brigatinib, a newly discovered AXL inhibitor, suppresses AXL-mediated acquired resistance to osimertinib in EGFR-mutated non-small cell lung cancer.

In addition to the classical resistance mechanisms, receptor tyrosine-protein kinase AXL is a main mechanism of resistance to third-generation epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) osimertinib in EGFR-mutated non-small cell lung cancer (NSCLC). Developing an effective AXL inhibitor is important to sensitize osimertinib in clinical application. In this study we assessed the efficacy of brigatinib, a second-generation of anaplastic lymphoma kinase (ALK)-TKI, as a novel AXL inhibitor, in overcoming acquired resistance to osimertinib induced by AXL activation. We established an AXL-overexpression NSCLC cell line and conducted high-throughput screening of a small molecule chemical library containing 510 anti-tumor drugs. We found that brigatinib potently inhibited AXL expression, and that brigatinib (0.5 μM) significantly enhanced the anti-tumor efficacy ofosimertinib (1 μM) in AXL-mediated osimertinib-resistant NSCLC cell lines in vitro. We demonstrated that brigatinib had a potential ability to bind AXL kinase protein and further inhibit its downstream pathways in NSCLC cell lines. Furthermore, we revealed that brigatinib might decrease AXL expression through increasing K48-linked ubiquitination of AXL and promoting AXL degradation in HCC827OR cells and PC-9OR cells. In AXL-high expression osimertinib-resistant PC-9OR and HCC827OR cells derived xenograft mouse models, administration of osimertinib (10 mg·kg-1·d-1) alone for 3 weeks had no effect, and administration of brigatinib (25 mg·kg-1·d-1) alone caused a minor inhibition on the tumor growth; whereas combination of osimertinib and brigatinib caused marked tumor shrinkages. We concluded that brigatinib may be a promising clinical strategy for enhancing osimertinib efficacy in AXL-mediated osimertinib-resistant NSCLC patients.

Detection of EGFR T790M mutation using liquid biopsy for non-small cell lung cancer: Utility of droplet digital polymerase chain reaction vs. cobas real-time polymerase chain reaction

BackgroundDigital platforms for mutation detection yield higher sensitivity than non-digital platforms but lack universal positive cut-off values that correlate with the outcome of osimertinib treatment. This study determined compared droplet digital polymerase chain reaction (ddPCR) to the standard cobas assay for epithelial growth factor receptor (EGFR) T790M mutation detection in patients with non-small cell lung cancer. MethodsStudy patients had EGFR-mutant tumours with disease progression on first/second generation EGFR tyrosine kinase inhibitors, and osimertinib treatment after T790M mutation detection. T790M status was tested by cobas assay using liquid biopsy, and only by ddPCR if an EGFR mutation was identified but T790M was negative. Clinical efficacy of osimertinib was compared between patients with T790M detected by cobas vs. only by ddPCR. A positive cut-off value for ddPCR was determined by assessing efficacy with osimertinib. Results61 patients had tumors with an acquired T790M mutation, 38 detected by cobas and an additional 23 only by ddPCR. The median progression-free survival (PFS) for the cobas- and ddPCR-positive groups was 9.5 and 7.8 months, respectively (p=0.43). For ddPCR, a fractional abundance (FA) of 0.1% was used as a cut-off value. The median PFS of patients with FA ≥0.1% and <0.1% was 8.3 and 4.6 months, respectively (p=0.08). FA ≥0.1% was independently associated with a longer PFS. ConclusionUsing ddPCR to follow up the cobas assay yielded more cases (38% of total) with a T790M mutation. A cut-off value of FA ≥0.1% identified patients who responded as well to osimertinib as those identified by cobas assay. This sequential approach should detect additional patients who might benefit from osimertinib treatment.

SOS2 modulates the threshold of EGFR signaling to regulate osimertinib efficacy and resistance in lung adenocarcinoma.

Son of sevenless 1 and 2 (SOS1 and SOS2) are RAS guanine nucleotide exchange factors (RasGEFs) that mediate physiologic and pathologic receptor tyrosine kinase (RTK)-dependent RAS activation. Here, we show that SOS2 modulates the threshold of epidermal growth factor receptor (EGFR) signaling to regulate the efficacy of and resistance to the EGFR tyrosine kinase inhibitor (EGFR-TKI) osimertinib in lung adenocarcinoma (LUAD). SOS2 deletion (SOS2KO ) sensitized EGFR-mutated cells to perturbations in EGFR signaling caused by reduced serum and/or osimertinib treatment to inhibit phosphatidylinositol 3-kinase (PI3K)/AKT pathway activation, oncogenic transformation, and survival. Bypassing RTK reactivation of PI3K/AKT signaling represents a common resistance mechanism to EGFR-TKIs; SOS2KO reduced PI3K/AKT reactivation to limit osimertinib resistance. In a forced HGF/MET-driven bypass model, SOS2KO inhibited hepatocyte growth factor (HGF)-stimulated PI3K signaling to block HGF-driven osimertinib resistance. Using a long-term in situ resistance assay, most osimertinib-resistant cultures exhibited a hybrid epithelial/mesenchymal phenotype associated with reactivated RTK/AKT signaling. In contrast, RTK/AKT-dependent osimertinib resistance was markedly reduced by SOS2 deletion; the few SOS2KO cultures that became osimertinib resistant primarily underwent non-RTK-dependent epithelial-mesenchymal transition (EMT). Since bypassing RTK reactivation and/or tertiary EGFR mutations represent most osimertinib-resistant cancers, these data suggest that targeting proximal RTK signaling, here exemplified by SOS2 deletion, has the potential to delay the development osimertinib resistance and enhance overall clinical responses for patients with EGFR-mutated LUAD.

Efficacy of osimertinib in patients with EGFR-mutation positive non-small cell lung cancer with malignant pleural effusion.

As an epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI), osimertinib has emerged as a standard EGFR-mutation positive treatment for non-small cell lung cancer (NSCLC). However, the efficacy of osimertinib for malignant pleural effusion (MPE) remains understudied. This study aimed to evaluate the impact of osimertinib on time to treatment failure (TTF) and overall survival (OS) in patients with EGFR-mutation positive NSCLC, comparing those with and without MPE. This retrospective analysis included patients with advanced or recurrent NSCLC treated with osimertinib at our hospital between April 2016 and June 2021. TTF was defined as the duration from osimertinib initiation to discontinuation, and OS as the duration until death, irrespective of the reason. Among 229 patients receiving osimertinib, 84 had MPE before administration, 39 acquired EGFR exon20 T790M mutation following previous EGFR-TKI therapy, and 45 were EGFR-TKI-naive. Among EGFR-TKI-naive patients, median TTF was 14.8 and 19.8 months for those with and without MPE, respectively (hazard ratio [HR] 1.40; 95% confidence interval [CI]: 0.90-2.18; p = 0.12). Median OS was 32.0 and 42.0 months for patients with and without MPE, respectively (HR 1.43; 95% CI: 0.86-2.38; p = 0.16). Among patients with T790M mutation, median TTF was 12.3 and 13.1 months for patients with and without MPE, respectively (HR 1.03; 95% CI: 0.69-1.55; p = 0.88). Median OS for patients with and without MPE was 23.2 and 24.7 months, respectively (HR 1.09; 95% CI: 0.72-1.67; p = 0.68). Among patients with EGFR-mutation positive NSCLC, the evidence of MPE has little effect on survival with osimertinib.

Enhancing intracranial efficacy prediction of osimertinib in non-small cell lung cancer: a novel approach through brain MRI radiomics.

Osimertinib, a third-generation EGFR-TKI, is known for its high efficacy against brain metastases (BM) in non-small cell lung cancer (NSCLC) due to its ability to penetrate the blood-brain barrier. This study aims to evaluate the use of brain MRI radiomics in predicting the intracranial efficacy to osimertinib in NSCLC patients with BM. This study analyzed 115 brain metastases from NSCLC patients with the EGFR-T790M mutation treated with second-line osimertinib. The primary endpoint was intracranial response, and the secondary endpoint was intracranial progression-free survival (iPFS). We performed tumor delineation, image preprocessing, and radiomics feature extraction. Using a 5-fold cross-validation strategy, we built radiomic models with eight feature selectors and eight machine learning classifiers. The models' performance was evaluated by the area under the receiver operating characteristic curve (AUC), calibration curves, and decision curve analysis. The dataset of 115 brain metastases was divided into training and validation sets in a 7:3 ratio. The radiomic model utilizing the mRMR feature selector and stepwise logistic regression classifier showed the highest predictive accuracy, with AUCs of 0.879 for the training cohort and 0.786 for the validation cohort. This model outperformed a clinical-MRI morphological model, which included age, ring enhancement, and peritumoral edema (AUC: 0.794 for the training cohort and 0.697 for the validation cohort). The radiomic model also showed strong performance in calibration and decision curve analyses. Using a radiomic-score threshold of 199, patients were classified into two groups with significantly different median iPFS (3.0 months vs. 15.4 months, p < 0.001). This study demonstrates that MRI radiomics can effectively predict the intracranial efficacy of osimertinib in NSCLC patients with brain metastases. This approach holds promise for assisting clinicians in personalizing treatment strategies.

Synergistic Anti-Tumor Efficacy Achieved by Reversing Drug Resistance through the Regulation of the Tumor Immune Microenvironment with IL-12 and Osimertinib Combination Therapy.

The objective of this study was to investigate the role of IL-12 in enhancing the anti-tumor efficacy of the small molecule targeted drug osimertinib in resistant tumor models and reversing resistance mechanisms. We utilized paired non-small cell lung cancer H1975 tumor tissues, establishing mouse tumor models with diverse tumor immune microenvironments. Analytical methods including immunohistochemistry and immunofluorescence were employed to compare immune cell infiltration, cytokines, effector molecules, and protein changes in resistant signaling pathways in tumor tissues, shedding light on IL-12's mechanism of action in enhancing osimertinib efficacy and reversing resistance. Results showed that osimertinib monotherapy had limited tumor suppression, whereas IL-12 exhibited more significant anti-tumor effects. Combination therapy groups demonstrated even greater tumor suppression with increased immune cell infiltration, elevated immune-related factor secretion, reduced immunosuppressive MDSCs, and decreased resistance-related signaling pathway markers. In conclusion, IL-12 enhances anti-tumor efficacy and reverses osimertinib resistance through various mechanisms, including increased immune cell infiltration, reduced immunosuppressive MDSCs, enhanced immune cell granzyme and IFN-γ release, decreased PDL-1 expression, improved tumor microenvironment, restored immune surveillance, and heightened cancer cell sensitivity to osimertinib.

Long-term efficacy of osimertinib in de novo exon 19 deletion with T790M in an epidermal growth factor receptor mutated lung cancer patient in India

Primary epidermal growth factor receptor (EGFR) T790M mutation is infrequently identified in previously untreated non-small cell lung cancer (NSCLC) patients. There is variation in the frequency of de novo T790M mutations depending on the population examined and the technology used for mutation detection. According to direct sequencing, 0.4–3% of all NSCLCs and 1–8% of all EGFR-mutant NSCLCs show primary T790M mutation. This mutation always coexists with a sensitizing EGFR mutation and is more commonly present along with exon 21 L858R mutation and infrequently with exon 19 deletion. Osimertinib, an oral irreversible third-generation EGFR tyrosine kinase inhibitor, is selective for both, EGFR sensitizing mutations and T790M resistance mutation. AURA trial has confirmed the effectiveness of osimertinib in patients with T790M mutation. The median progression-free survival is better in primary T790M as compared to the acquired mutation in a previously treated NSCLC. The overall survival with osimertinib is still 38.6 months only. Even after good response in both primary and acquired T790M mutation, there is disease progression and shifting to chemotherapy is required. We present an interesting case of a 60-year-old non-smoker female deriving benefit from a single agent osimertinib with a rare combination of mutation at presentation even after 6 years of initiation of therapy.

O7-2 A phase II study to assess the efficacy of osimertinib in patients with EGFR MT(+)T790M(-) NSCLC

O7-2 A phase II study to assess the efficacy of osimertinib in patients with EGFR MT(+)T790M(-) NSCLC

P2.09-29 Efficacy of Osimertinib (OSI) vs 1st-Generation TKI Followed by OSI by Clinical Profile in EGFR-Mutant NSCLC (SMILE STUDY)

P2.09-29 Efficacy of Osimertinib (OSI) vs 1st-Generation TKI Followed by OSI by Clinical Profile in EGFR-Mutant NSCLC (SMILE STUDY)

MA05.10 Patient-Initiated a Phase II study (WJOG12819L) to Assess the Efficacy of Osimertinib in Patients with EGFR Mutated T790M-Negative NSCLC

MA05.10 Patient-Initiated a Phase II study (WJOG12819L) to Assess the Efficacy of Osimertinib in Patients with EGFR Mutated T790M-Negative NSCLC

A Phase II Study of Osimertinib in Patients with Advanced-Stage Non-Small Cell Lung Cancer following Prior Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor (EGFR TKI) Therapy with EGFR and T790M Mutations Detected in Plasma Circulating Tumour DNA (PLASMA Study).

Epidermal growth factor receptor (EGFR) T790M mutations drive resistance in 50% of patients with advanced non-small cell lung cancer (NSCLC) who progress on first/second generation (1G/2G) EGFR tyrosine kinase inhibitors (TKIs) and are sensitive to Osimertinib. Tissue sampling is the gold-standard modality of T790M testing, but it is invasive. We evaluated the efficacy of Osimertinib in patients with EGFR mutant NSCLC and T790M in circulating tumour DNA (ctDNA). PLASMA is a prospective, open-label, multicentre single-arm Phase II study. Patients with advanced NSCLC harbouring sensitizing EGFR and T790M mutations in plasma at progression from ≥one 1G/2G TKI were treated with 80 mg of Osimertinib daily until progression. The primary endpoint was the objective response rate (ORR); the secondary endpoints included progression-free survival (PFS), overall survival (OS), disease control rate (DCR) and toxicities. Plasma next-generation sequencing was performed to determine Osimertinib resistance mechanisms and assess serial ctDNA. A total of 110 patients from eight centres in five countries were enrolled from 2017 to 2019. The median follow-up duration was 2.64 (IQR 2.44-3.12) years. The ORR was 50.9% (95% CI 41.2-60.6) and the DCR was 84.5% (95% CI 76.4-90.7). Median PFS was 7.4 (95% CI 6.0-9.3) months; median OS was 1.63 (95% CI 1.35-2.16) years. Of all of the patients, 76% had treatment-related adverse events (TRAEs), most commonly paronychia (22.7%); 11% experienced ≥ Grade 3 TRAEs. The ctDNA baseline load and dynamics were prognostic. Osimertinib is active in NSCLC harbouring sensitizing EGFR and T790M mutations in ctDNA testing post 1G/2G TKIs.

A Phase 2 Single-Arm Study of Osimertinib for Radiotherapy-Naive Central Nervous System Metastasis NSCLC: Results for the First-Line Cohort of the OCEAN Study (LOGIK 1603/WJOG 9116L)

IntroductionOsimertinib may be effective in treating central nervous system (CNS) metastasis, but its efficacy in treating radiation therapy (RT)-naive metastasis is unclear. The OCEAN study assessed the efficacy of osimertinib against RT-naive CNS metastasis in patients previously treated (T790M cohort) and untreated patients (first-line cohort) with EGFR mutation. Here, we report the results of the first-line cohort. MethodsPreviously untreated patients with RT-naive CNS metastasis and EGFR mutation-positive NSCLC were treated with osimertinib. The brain metastasis response rate (BMRR), progression-free survival (PFS), and overall survival in the first-line cohort were secondary end points. ResultsA total of 26 patients were enrolled in the study between September 2019 and July 2020. The median age was 72.0 years with 80.8% female. There were 20 patients who had multiple CNS metastases. BMRR assessed by PAREXEL criteria was 76.9% (90% confidence interval [CI]: 63.3%–90.5%), BMRR assessed by Response Evaluation Criteria in Solid Tumors was 76.9% (95% CI: 54.0%–99.8%), and median PFS of CNS metastasis was 22.0 months (95% CI: 9.7 mo–not reached). The overall response rate was 64.0% (95% CI: 45.2%–82.8%), median PFS was 11.5 months (95% CI: 6.9 mo–not reached), and median survival time was 23.7 months (95% CI: 16.5 mo–not reached). Paronychia and increased creatinine level were the most frequent nonhematological toxicities observed in 13 patients (50%). Grade three and higher adverse events were less than 10%, and there were no treatment-related deaths. Pneumonitis was observed in five patients (19.2%). ConclusionsThese results suggest that osimertinib is effective in untreated patients with RT-naive asymptomatic CNS metastasis in a clinical practice first-line setting. Trial registrationUMIN identifier: UMIN000024218. jRCT identifier: jRCTs071180017.

Osimertinib induces paraptosis and TRIP13 confers resistance in glioblastoma cells

The efficacy of osimertinib, a third-generation epidermal growth factor receptor tyrosine kinase inhibitor, has been evaluated in glioblastoma (GBM) through preclinical and clinical trials. However, the underlying mechanism of osimertinib-induced GBM cell death and the underlying resistance mechanism to osimertinib remains unclear. Here, we demonstrate that Osimertinib induces paraptosis in GBM cells, as evidenced by the formation of cytoplasmic vacuoles, accumulation of ubiquitinated proteins, and upregulation of endoplasmic reticulum (ER) stress markers like CHOP. Additionally, neither apoptosis nor autophagy was involved in the osimertinib-induced cell death. RNAseq analysis revealed ER stress was the most significantly downregulated pathway upon exposure to osimertinib. Consistently, pharmacologically targeting the PERK-eIF2α axis impaired osimertinib-induced paraptosis. Notably, we show that the expression of thyroid receptor-interacting protein 13 (TRIP13), an AAA+ATPase, alleviated osimertinib-triggered paraptosis, thus conferring resistance. Intriguingly, MK-2206, an AKT inhibitor, downregulated TRIP13 levels and synergized with Osimertinib to suppress TRIP13-induced high GBM cell growth in vitro and in vivo. Together, our findings reveal a novel mechanism of action associated with the anti-GBM effects of osimertinib involving ER stress-regulated paraptosis. Furthermore, we identify a TRIP13-driven resistance mechanism against Osimertinib in GBM and offer a combination strategy using MK-2206 to overcome such resistance.

A homologous and molecular dual-targeted biomimetic nanocarrier for EGFR-related non-small cell lung cancer therapy.

The abnormal activation of epidermal growth factor receptor (EGFR) drives the development of non-small cell lung cancer (NSCLC). The EGFR-targeting tyrosine kinase inhibitor osimertinib is frequently used to clinically treat NSCLC and exhibits marked efficacy in patients with NSCLC who have an EGFR mutation. However, free osimertinib administration exhibits an inadequate response in vivo, with only ∼3% patients demonstrating a complete clinical response. Consequently, we designed a biomimetic nanoparticle (CMNP@Osi) comprising a polymeric nanoparticle core and tumor cell-derived membrane-coated shell that combines membrane-mediated homologous and molecular targeting for targeted drug delivery, thereby supporting a dual-target strategy for enhancing osimertinib efficacy. After intravenous injection, CMNP@Osi accumulates at tumor sites and displays enhanced uptake into cancer cells based on homologous targeting. Osimertinib is subsequently released into the cytoplasm, where it suppresses the phosphorylation of upstream EGFR and the downstream AKT signaling pathway and inhibits the proliferation of NSCLC cells. Thus, this dual-targeting strategy using a biomimetic nanocarrier can enhance molecular-targeted drug delivery and improve clinical efficacy.

Clinicopathological impact of VEGFR2 and VEGF-C in patients with EGFR-major mutant NSCLC receiving osimertinib.

Vascular endothelial growth factor (VEGF) has been identified as one of the resistant mechanisms to epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs). However, the relationship between the efficacy of osimertinib and protein expression of VEGF family members in patients with advanced non-small cell lung cancer (NSCLC) harboring EGFR mutations remains unclear. A total of 76 patients with advanced NSCLC with EGFR major mutations (del19 or L858R) receiving first-line osimertinib were eligible as the osimertinib (Osi) group, whereas 43 patients receiving first- or second-generation EGFR-TKIs were compared with the control group. The expression of vascular endothelial growth factor receptor 2 (VEGFR2) and vascular endothelial growth factor C (VEGF-C) in the tumor specimens was analyzed using immunohistochemistry. VEGFR2 and VEGF-C were highly expressed in 65.8% and 51.3% of patients, respectively, in the Osi group, and 69.7% and 76.7%, respectively, in the control group. High VEGFR2 and VEGF-C levels were significantly associated with poor performance status (PS) and female sex, respectively. In the Osi group, patients with co-high expression of VEGFR2 and VEGF-C showed significantly worse progression-free survival (PFS) and overall survival (OS) than those without co-high expression. In del19, VEGFR2 was a significant predictor of PFS and OS and independent predictor of OS in multivariate analysis. In L858R, co-high expression of VEGFR2 and VEGF-C was identified as a significant predictor of PFS and OS and independent predictor of PFS. VEGFR2 and VEGF-C are highly expressed in EGFR-mutant NSCLC cells. Increased expression of VEGFR2 was identified as a significant prognostic factor in patients with EGFR del19 mutation who received osimertinib, whereas co-high expression of VEGFR2 and VEGF-C was a significant predictor for those with EGFR L858R mutation.

Osimertinib is a dual inhibitor of hepatocellular carcinoma and angiogenesis in an EGFR-independent manner, and synergizes with venetoclax.

To investigate the effects of osimertinib on hepatocellular carcinoma (HCC) and angiogenesis, and its combinatory effects with venetoclax in HCC. Viability was assessed by flow cytometry of Annexin V in multiple HCC cell lines after drug treatment. In vitro angiogenesis assay was performed using primary human liver tumor associated endothelial cell (HLTEC). HCC-bearing model was generated by subcutaneous implantation of Hep3B cells to investigate the efficacy of osimertinib alone and its combination with venetoclax. Osimertinib significantly induced apoptosis in a panel of HCC cell lines regardless of EGFR expression level. It inhibited capillary network formation and induced apoptosis in HLTEC. Using HCC xenograft mouse model, we further showed that osimertinib at non-toxic dose inhibited tumor growth by ~ 50% and remarkably decreased blood vessel in tumor. Mechanism studies demonstrated that osimertinib acted on HCC cells in an EGFR-independent manner. It decreased level of VEGF and Mcl-1 in HCC cells via suppressed phosphorylation of eIF4E, thus leading to inhibition of eIF4E-mediated translation. Mcl-1 overexpression reversed pro-apoptotic effect of osimertinib, suggesting an important role of Mcl-1 in osimertinib's action in HCC cells. Of note, the combination of osimertinib and venetoclax achieved approximately complete HCC cell death and tumor growth in mice. We provide pre-clinical evidence that osimertinib is a promising candidate for the treatment of HCC via targeting tumor cells and angiogenesis. The combination of osimertinib and venetoclax is synergistic in inhibiting HCC.

Safety and efficacy of osimertinib plus bevacizumab as first-line treatment in EGFR-mutated NSCLC with brain metastasis instructed by dynamic monitoring circulating tumor DNA of paired cerebrospinal fluid and plasma.

e21182 Background: The management of brain metastases in lung cancer was always a global challenge. Studies have shown that erlotinib combined with bevacizumab could bring progression-free survival benefit for NSCLC. Osimertinib is a third-generation EGFR tyrosine kinase inhibitor with higher CNS penetration. This study was to evaluate the safety and efficacy of osimertinib plus bevacizumab as the first-line treatment for patients with EGFR-positive NSCLC and brain metatases, and reveal the molecular characteristics of intracranial progression by matching plasma and CSF ctDNA. Methods: Patients with EGFR-positive NSCLC and brain metatases were treated with osimertinib (80mg, daily) plus bevacizumab (5mg/kg, every 4 week) as the first-line treatment. CSF and paird plasma ctDNA were collected before osimertinib and at the time of disease stable, intracranial progression and systematic progression, using the next-generation sequencing (NGS) to explore the dynamic changes between them. The primary end point was median CNS progression-free survival (PFS), CNS objective response rate (ORR). The second end point was to explore the molecular mechanism of CNS progression. Results: As the time of data cutoff (Jan 31, 2023), 15 patients were enrolled. 3 patients (20%) progressed in lung, 2 patients (13.3%) progressed in brain, and 1 patient (6.7%) progressed in leptomeningeal and bone, 2 of them still received oral osimertinib (80mg, daily). 9 patients (60%) were in partial or complete reponse and 8 of them continued to receive the original treatment. The median osimertinib exposure time was 16.8 months. The median bevacizumab exposure time was 9.1 months. The median CNS progression-free survival was 15.5 months (6.8 months to not reached). The CNS objective response rate was 93.33%. Six patients received gamma knife radiotherapy before Osimertinib, the median CNS progression-free survival was 14 months (6.8 months to not reached), the CNS objective response rate was 100%. After progression on Osimertinib, paired CSF and plasma ctDNA were analyzed and EGFR C797S, TP53, CDKN2A and etc could be found as resistanct mechanism. Adverse events of grade 3 or worse were observed in 1 patients (6.7%): severe ulcerative colitis, leading to the suspension of osimertinib. 2 patients (13.3%) stopped bevacizumab because of bleeding. Conclusions: This is a mid-term report with immature data. By the end of follow-up, we expected that osimertinib plus bevacizumab could better reduce the risk of intracranial progression and prolong the progression-free survival compared with osimertinib monotherapy. Clinical trial information: KY2021-155-02.

Uncommon EGFR mutations conducted with osimertinib in patients with NSCLC (UNICORN): A phase 2 study.

9045 Background: Non-small cell lung cancer (NSCLC) harboring uncommon EGFR mutation (uC- EGFRm), excluding exon 20 insertion, is a heterogenous rare fraction consisting of 10% of all EGFR mutations. Key drugs for metastatic NSCLC (mNSCLC) uC- EGFRm are limited, with only afatinib being FDA approved. Data on the efficacy of osimertinib for previously untreated metastatic patients (pts) harboring uC- EGFRm NSCLC is limited. Methods: UNICORN study for previously untreated mNSCLC pts harboring uC- EGFRm, excluding exon 20 insertion mutation, evaluating osimertinib with a dose of 80 mg QD orally is a multicenter, open-label, single-arm phase 2 study. The primary endpoint was the overall response rate (ORR) evaluated by central review according to the Response Evaluation Criteria in Solid Tumors (version 1.1), and key secondary endpoints were disease control rate (DCR), progression-free survival (PFS), overall survival (OS), duration of response (DoR), and safety. Results: Between March 2020 to May 2022, a total of 42 pts were registered. Among the eligible 40 pts, 45.0% were female; the median age was 72 years (range 39-88); 42.5% were never smokers or light smokers; 92.5% were adenocarcinomas, solitary uC- EGFRm/compound mutation ratio was 57.5%/42.5%. The most common mutations were G719X (50.0%), followed by S768I (25.0%), L861Q (20.0%), and others, including compound mutation data. The ORR was 55.0 % (90% confidence interval [CI]; 40.9-68.5), the DCR was 90.0 % (95% CI; 76.3-97.2), the mPFS was 9.4 months (95% CI; 3.7-15.2) after a median follow-up of 27.0 months, the mOS was not reached (NR) (95% CI, 19.23- NR), and the mDoR 22.7 months (95% CI; 9.43-NR). In solitary and compound mutations with uC- EGFR m NSCLC, ORR was 52.2%/58.8%, mPFS was 5.4 months/11.4 months, mOS 23.0 months/NR, and mDoR was 22.7 months/NR, respectively. Safety was similar to previous reports and Grade 3/4 AEs were reported in 8 of 36 pts (27.5%) and 12.5% of pts developed pneumonitis. All of the AEs were manageable and there were no treatment-related deaths. Conclusions: Osimertinib in mNSCLC pts harboring uC- EGFRm other than exon 20 insertions showed clinical activity with manageable toxicities. These results suggest that osimertinib can be considered as a treatment option for this specific population. Clinical trial registration: jRCTs071200002. The study was funded by AstraZeneca. Clinical trial information: jRCTs071200002 .