A randomized, open-label, multicenter, adaptive phase 2/3 study of trastuzumab emtansine (T-DM1) versus a taxane (TAX) in patients (pts) with previously treated HER2-positive locally advanced or metastatic gastric/gastroesophageal junction adenocarcinoma (LA/MGC/GEJC).

2016 ◽  
Vol 34 (4_suppl) ◽  
pp. 5-5 ◽  
Author(s):  
Yoon-Koo Kang ◽  
Manish A. Shah ◽  
Atsushi Ohtsu ◽  
Eric Van Cutsem ◽  
Jaffer A. Ajani ◽  
...  
Keyword(s):  
Targeted Therapy ◽  
Gastroesophageal Junction ◽  
Locally Advanced ◽  
Data Monitoring Committee ◽  
Metastatic Breast ◽  
Standard Of Care ◽  
Phase 2 ◽  
Her2 Positive ◽  
Open Label ◽  
Previously Treated

5 Background: Trastuzumab (H) + capecitabine/fluorouracil + cisplatin is standard of care for 1st-line HER2-positive MGC/GEJC but there is no established HER2-targeted 2nd-line regimen. T-DM1 (H linked to DM1) is approved for HER2-positive metastatic breast cancer previously treated with H + TAX (separately or in combination). This and preclinical HER2-positive GC models provided the rationale for GATSBY (NCT01641939). Methods: GATSBY is a 3-arm randomized, adaptive, seamless phase 2/3 global study of T-DM1 vs TAX in pts with HER2-positive (immunohistochemistry [IHC] 3+ or IHC 2+/in situ hybridization-positive), unresectable LA/MGC/GEJC who progressed during or after 1st-line fluoropyrimidine + platinum ± HER2-targeted therapy. Pts were initially randomized 2:2:1 to T-DM1 3.6 mg/kg every 3 weeks (q3w), T-DM1 2.4 mg/kg weekly (qw), or physician’s choice of paclitaxel 80 mg/m2 qw or docetaxel 75 mg/m2q3w. An independent data monitoring committee selected T-DM1 qw for further study and subsequent patients were randomized 2:1 to this or TAX. The primary endpoint is overall survival (OS); all T-DM1 qw data are analyzed, including dose selection. Results: At clinical cutoff, 06/30/15, 415 pts had been randomized overall: 228 to T-DM1 qw, 117 to TAX (70 T-DM1 q3w pts reported separately); 77.4% had prior HER2-targeted therapy; 29.9% prior gastrectomy; 46.1% were Asian. Efficacy/safety are tabulated. Conclusions: T-DM1 2.4 mg/kg qw did not show an efficacy benefit over TAX. Grade ≥3 AE rates were numerically lower with T-DM1 vs TAX and rates of SAEs, fatal AEs, and treatment discontinuations due to AEs were comparable between arms. Clinical trial information: NCT01641939. [Table: see text]

MOUNTAINEER-02: Phase II/III study of tucatinib, trastuzumab, ramucirumab, and paclitaxel in previously treated HER2+ gastric or gastroesophageal junction adenocarcinoma—Trial in Progress.

2021 ◽  
Vol 39 (3_suppl) ◽  
pp. TPS252-TPS252
Author(s):  
John H. Strickler ◽  
Yoshiaki Nakamura ◽  
Takayuki Yoshino ◽  
Daniel V.T. Catenacci ◽  
Yelena Y. Janjigian ◽  
...  
Keyword(s):  
Gastroesophageal Junction ◽  
Locally Advanced ◽  
Metastatic Breast ◽  
Her2 Status ◽  
Phase 2 ◽  
Efficacy And Safety ◽  
Open Label ◽  
Phase 3 ◽  
Double Blind ◽  
Gastroesophageal Junction Adenocarcinoma

TPS252 Background: Tucatinib (TUC), a highly selective HER2-directed TKI recently approved for HER2+ metastatic breast cancer (MBC), is being developed as a novel therapy for patients (pts) with metastatic colorectal cancer (mCRC) and other GI tumors. While trastuzumab (Tras) with chemotherapy is standard in the 1st-line setting for metastatic HER2+ gastric or gastroesophageal junction adenocarcinoma (GEC), no anti-HER2 therapy has demonstrated an OS benefit over chemotherapy in 2nd-line, possibly due to loss of HER2 expression following Tras-based therapy. In GEC xenograft models, dual targeting of HER2 with TUC and Tras showed superior activity to either agent alone. Interim results from the MOUNTAINEER study have shown promising activity for TUC and Tras in HER2+ mCRC. The MOUNTAINEER-02 study is evaluating the efficacy and safety of TUC in combination with Tras, ramucirumab (Ram), and paclitaxel (Pac) in pts with HER2+ GEC. Methods: MOUNTAINEER-02 (NCT04499924) is a phase 2/3 study evaluating TUC and Tras with the 2nd-line standard of care, Ram and Pac. Pts receive TUC 300 mg or placebo PO BID, Tras (6 then 4 mg/kg) or placebo (IV on Days 1 and 15 of each 28-day cycle), Pac (IV on Days 1, 8, 15), and Ram (IV on Days 1 and 15). Eligible pts have locally-advanced unresectable or metastatic HER2+ GEC, have received a HER2-directed antibody, and 1 prior line of therapy for advanced disease. Pts must be ≥18 years of age, with an ECOG ≤1, and have had no prior exposure to Ram, anti-HER2 or anti-EGFR TKI, HER2-directed antibody-drug conjugates, or taxanes ≤12 months before enrollment. Due to the potential impact of TUC on Pac metabolism, the study will include an initial Pac dose finding stage. The open-label phase 2 part will determine the recommended dose of Pac (60 or 80 mg/m²) combined with TUC, Tras, and Ram in 6-12 patients, and evaluate the safety and activity of the regimen in Cohorts 2A and 2B (30 patients each). The randomized, double-blind, phase 3 part will compare the efficacy and safety of TUC and Tras (Arm 3A; ~235 patients) vs. placebo (Arm 3B; ~235 patients), both in combination with Ram and Pac, and also evaluate activity of TUC with Ram and Pac (Arm 3C; ~30 patients). The dual primary phase 3 endpoints are OS and PFS per investigator, with confirmed ORR as a key secondary endpoint. HER2 status is determined at baseline using a blood-based NGS assay, and IHC/ISH of fresh or archival tumor biopsies, if available. Pts must be HER2+ by blood-based NGS in Cohort 2A and phase 3; in Cohort 2B, pts must be HER2+ in a biopsy taken post-progression during/after 1st-line therapy, but HER2-negative by blood-based NGS. Disease assessments per RECISTv1.1 will occur q6 weeks for 36 weeks, then q9 weeks. The pharmacokinetics of TUC, Pac, and their metabolites will be evaluated in a subset of pts, including a cohort with gastrectomies. Enrollment is ongoing in the U.S. Clinical trial information: NCT04499924.

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