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Shinji Takeuchi



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    P1.14 - Targeted Therapy (ID 182)

    • Event: WCLC 2019
    • Type: Poster Viewing in the Exhibit Hall
    • Track: Targeted Therapy
    • Presentations: 1
    • Moderators:
    • Coordinates: 9/08/2019, 09:45 - 18:00, Exhibit Hall
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      P1.14-35 - Epithelial-To-Mesenchymal Transition Is a Mechanism of ALK Inhibitor Resistance in Lung Cancer Independent of ALK Mutation Status (ID 671)

      09:45 - 18:00  |  Author(s): Shinji Takeuchi

      • Abstract
      • Slides

      Background

      ALK rearrangement, most commonly EML4-ALK, is detected in approximately 3%–5% of NSCLC. ALK tyrosine kinase inhibitor (TKI), shows dramatic clinical efficacy, however, almost all patients acquire resistance over time. The most defined mechanism of crizotinib resistance is secondary ALK mutations. A recent study reported that epithelial-to-mesenchymal transition(EMT) and ALK resistance mutation were simultaneously detected in a single tumor lesion in patients with ALK-rearranged lung cancer who were resistant to ALK-TKIs. However, it is still unknown whether ALK-TKI resistant tumor cells combine mesenchymal phenotype with ALK resistance mutation, or each of the mesenchymal type tumor cells and ALK resistance mutation–positive cells coexist in a single lesion. In any of these cases, no therapy for EMT-associated targeted drug resistance has yet been established.

      Method

      Specimens from a patient with ALK-rearranged lung adenocarcinoma who acquired resistance to crizotinib were stained with IHC, and the epithelial regions (ALK+, vimentin+, and E-cadherin) and the mesenchymal regions (ALK+, vimentin, and E-cadherin+) were collected by microdissection. The DNA from the each regions were isolated and the ALK L1196M mutation was detected by degital PCR analysis. Crizotinib-resistant cell line was developed by continuous treatment with crizotinib in the pleural carcinomatosis mouse model inoculated with the crizotinib-sensitive human lung cancer cell line, A925LPE3, which harbors the EML4-ALK gene fusion. The clones were estabilish by limiting dilution and the mechanism of crizotinib resistance was examined by microarray analysis, miRNA array analysis, western blot, and MTT assay. Compounds that overcame crizotinib resistance were screened from a library of 200 kinase inhibitors.

      Result

      Digital PCR analyses combined with microdissection after IHC staining for EMT markers revealed that ALK L1196M was predominantly detected in epithelial-type tumor cells, indicating that mesenchymal phenotype and ALK mutation can coexist as independent mechanisms underlying ALK inhibitor–resistant cancers. Preclinical experiments with crizotinib-resistant lung cancer cells showed that EMT associated with decreased expression of miR-200c and increased expression of ZEB1 caused cross-resistance to new-generation ALK inhibitors alectinib, ceritinib, and lorlatinib. Moreover, pretreatment with the histone deacetylase (HDAC) inhibitor quisinostat overcame this resistance by reverting EMT in vitro and in vivo.

      Conclusion

      These findings indicate that HDAC inhibitor pretreatment followed by a new ALK inhibitor may be useful to circumvent resistance constituted by coexistence of resistance mutations and EMT in the heterogeneous tumor.

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    P2.14 - Targeted Therapy (ID 183)

    • Event: WCLC 2019
    • Type: Poster Viewing in the Exhibit Hall
    • Track: Targeted Therapy
    • Presentations: 1
    • Moderators:
    • Coordinates: 9/09/2019, 10:15 - 18:15, Exhibit Hall
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      P2.14-56 - Osimertinib Overcomes Alectinib Resistance Caused by Amphiregulin in a Leptomeningeal Carcinomatosis Model of EML4-ALK Lung Cancer (ID 1543)

      10:15 - 18:15  |  Author(s): Shinji Takeuchi

      • Abstract
      • Slides

      Background

      Central nervous system (CNS) metastasis, such as brain metastasis and leptomeningeal carcinomatosis (LMC), occurs in 20–40% of all patients with cancer. Anaplastic lymphoma kinase (ALK) is a clinically validated drug target and ALK rearrangements are found in approximately 3-5% of non-small cell lung cancer (NSCLC). ALK tyrosine kinase inhibitor (TKI) shows dramatic clinical efficacy in ALK-rearranged NSCLC patients, and the second-generation ALK-TKI alectinib is effective against CNS metastasis of ALK-rearranged NSCLC. However, the patients with ALK-rearrangement acquire resistance to alectinib over time and develop recurrent LMC metastasis. This study aimed to clarify the mechanism of resistance to alectinib in LMC and seek a novel therapeutic strategy.

      Method

      Alectinib-resistant cell line (A925L/AR) was established by continuous treatment with alectinib in the LMC mouse model inoculated with the alectinib-sensitive human lung cancer cell line, A925LPE3, which harbors the EML4-ALK gene fusion. The tumor level was measured by in vivo imaging system. To clarify the mechanism of alectinib resistance, tumor cell culture supernatants, patient cerebrospinal fluid (CSF), and patient serum were measured using ELISA kits for EGFR ligands.

      Result

      A925L/AR cells were moderately resistant to various ALK-TKIs, such as alectinib, crizotinib, ceritinib, and lorlatinib, compared with parental cells in vitro. A925L/AR cells acquired resistance through epidermal growth factor receptor (EGFR) activation due to overexpression of its ligand, amphiregulin. EGFR-TKIs and anti-EGFR antibodies re-sensitized A925L/AR cells to alectinib in vitro. In the LMC model with A925L/AR cells, combined treatment with alectinib and an EGFR-TKI, such as erlotinib and osimertinib, successfully controlled LMC progression. Imaging mass spectrometry showed accumulation of EGFR-TKIs in the tumor lesions. Moreover, notably high amphiregulin levels were detected in the cerebrospinal fluid from ALK-rearranged NSCLC patients with alectinib-resistant LMC compared with those in EGFR-mutated NSCLC patients with EGFR-TKI-resistant LMC or patients without LMC.

      Conclusion

      We demonstrated that EML4-ALK lung cancer cells acquired moderate resistance to alectinib in the leptomeningeal space due to amphiregulin-triggered EGFR activation. Moreover, combined use of alectinib and EGFR-TKIs, including the third-generation inhibitor osimertinib, could overcome resistance in the LMC model. Our findings may provide rationale for clinical trials to investigate the effects of novel therapies dual-targeting ALK and EGFR in ALK-rearranged NSCLC with alectinib-resistant LMC.

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    PL02 - Presidential Symposium including Top 7 Rated Abstracts (ID 89)

    • Event: WCLC 2019
    • Type: Plenary Session
    • Track:
    • Presentations: 1
    • Now Available
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      PL02.08 - Registrational Results of LIBRETTO-001: A Phase 1/2 Trial of LOXO-292 in Patients with RET Fusion-Positive Lung Cancers (Now Available) (ID 964)

      08:00 - 10:15  |  Author(s): Shinji Takeuchi

      • Abstract
      • Presentation
      • Slides

      Background

      No targeted therapy is currently approved for patients with RET fusion-positive non-small cell lung cancer (NSCLC). LOXO-292 is a highly selective RET inhibitor with activity against diverse RET fusions, activating RET mutations and brain metastases. Based on initial data from LIBRETTO-001, LOXO-292 received FDA Breakthrough Designation for the treatment of RET fusion-positive NSCLC in August 2018.

      Method

      This global phase 1/2 study (87 sites, 16 countries) enrolled patients with advanced RET-altered solid tumors including RET fusion-positive NSCLC (NCT03157128). LOXO-292 was dosed orally in 28-day cycles. The phase 1 portion established the MTD/RP2D (160 mg BID). The phase 2 portion enrolled patients to one of six cohorts based on tumor type, RET alteration, and prior therapies. The primary endpoint was ORR (RECIST 1.1). Secondary endpoints included DoR, CNS ORR, CNS DoR, PFS, OS, safety and PK.

      Result

      As of 17-June 2019, 253 RET fusion-positive NSCLC patients were treated. The primary analysis set (PAS) for LOXO-292 registration, as defined with the US FDA, consists of the first 105 consecutively enrolled RET fusion-positive NSCLC patients who received prior platinum-based chemotherapy; 58 patients (55%) also received prior anti PD-1/PD-L1 agents. The majority of PAS responders have been followed for ≥6 months from first response. Of the remaining 148 patients, 79 had previously been treated with platinum-based chemotherapy, 55 did not receive prior platinum-based chemotherapy and 14 did not have measurable disease at baseline.

      Among PAS patients, the investigator-assessed ORR was 68% (95% CI 58-76%, n=71/105, 2 PRs pending confirmation). Responses did not differ by fusion partner or the type or number of prior therapies, including chemotherapy, anti PD-1/PD-L1 agents and multikinase inhibitors with anti-RET activity. The median DoR was 20.3 months (95% CI 13.8-24.0) with a median follow-up of 8 months; as evidenced by the wide confidence interval, this DoR estimate is not statistically stable due to a low number of events (16 of 69 confirmed responders). The intracranial ORR was 91% (n=10/11: 2 confirmed CRs, 8 confirmed PRs) for patients with measurable brain metastases at baseline.

      The ORR in efficacy evaluable treatment naïve RET fusion-positive NSCLC patients was 85% (95% CI 69-95%, n=29/34, 7 PRs pending confirmation). In the safety data set of all 531 patients, 5 treatment-related AEs occurred in ≥15% of patients: dry mouth, diarrhea, hypertension, increased AST and increased ALT. Most AEs were grade 1-2. Only 9 of 531 (1.7%) patients discontinued LOXO-292 for treatment-related AEs.

      Conclusion

      LOXO-292 had marked antitumor activity in RET fusion-positive NSCLC patients and was well tolerated. These data will form the basis of an FDA NDA submission later this year.

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