Zanidatamab demonstrated a median overall survival (OS) of 15.5 months in patients with centrally confirmed immunohistochemistry (IHC) 2+ or 3+ and a median OS of 18.1 months in patients with IHC 3+ tumors
With approximately two years of median follow-up, as of July 28, 2023, median duration of response (DOR) increased by two months from initial analysis to 14.9 months
DUBLIN, June 1, 2024 /PRNewswire/ -- Jazz Pharmaceuticals plc (Nasdaq: JAZZ) today announced long-term follow-up results, including the first-ever overall survival (OS) findings, from the Phase 2b HERIZON-BTC-01 clinical trial of zanidatamab in previously treated, unresectable, locally advanced, or metastatic HER2-positive biliary tract cancer (BTC). These data will be featured at the American Society of Clinical Oncology (ASCO) Annual Meeting in a poster presentation during the Gastrointestinal Cancer – Gastroesophageal, Pancreatic, and Hepatobiliary session on June 1, 2024, at 1:30-4:30 p.m. CDT. Zanidatamab is a human epidermal growth factor receptor 2 (HER2)-targeted bispecific antibody being studied in multiple solid tumors.
For the trial's primary endpoint, results demonstrated that a confirmed objective response rate (cORR) by independent central review (ICR) was maintained at 41.3% (95% confidence interval (CI): 30.4, 52.8) and one additional patient achieved a complete response (n=2; 2.5%) since initial findings were presented at the ASCO Annual Meeting in 2023. The median duration of response (DoR), one of the trial's key secondary endpoints, increased by approximately 2 months to 14.9 months (95% CI: 7.4, not reached), compared to the previously reported findings. In this data cut, zanidatamab demonstrated a median estimated OS, another secondary endpoint, of 15.5 months (95% CI: 10.4, 18.5) in all patients with HER2+ BTC, 18.1 months (95% CI:12.2, 23.2) in patients with IHC 3+ tumors, and 5.2 months (95% CI: 3.1, 10.2) in patients with IHC 2+ tumors. Results highlight the clinically meaningful benefits of sustained and durable responses with continued treatment with zanidatamab.
"Patients with BTC are typically diagnosed when their disease is at an advanced stage, which is associated with a poor prognosis," said Shubham Pant, M.D., M.B.B.S. professor in the Department of Gastrointestinal Medical Oncology and Investigational Cancer Therapeutics at The University of Texas MD Anderson Cancer Center. "Historically, overall survival with standard-of-care chemotherapy in second-line patients with advanced BTC is reported to be between 6-9 months1 so there is a significant unmet need for targeted therapies that can potentially improve survival. The deep and durable responses seen in this study signal the potential to fill a critical unmet patient need with zanidatamab, a chemotherapy-free option, among patients with HER2-expressing cancers."
"We are encouraged by the updated results from the pivotal HERIZON-BTC-01 trial demonstrating sustained clinical activity in previously treated patients with advanced HER2-positive BTC. Results from HERIZON-BTC-01 were included in the Biologics License Application (BLA) for zanidatamab, which was granted Priority Review by the FDA earlier this week, as well as in the Marketing Authorization Application for zanidatamab which was recently submitted to the European Medicines Agency," said Rob Iannone, M.D., M.S.C.E., executive vice president, global head of research and development of Jazz Pharmaceuticals. "Clinical development of zanidatamab for the treatment of advanced HER2-positive BTC continues with HERIZON-BTC-302 (NCT06282575), the ongoing, global, randomized Phase 3 trial of zanidatamab in combination with standard-of-care therapy in the first-line setting for patients with HER2-positive BTC. We also look forward to investigating zanidatamab's potential in other HER2-expressing solid tumors, including in cases resistant to prior HER2-targeted therapies."
Trial Results
Results from this long-term analysis of the Phase 2b HERIZON-BTC-01 trial (NCT04466891) indicate that zanidatamab monotherapy demonstrated sustained and durable antitumor responses in previously treated patients with HER2-positive unresectable, locally advanced, or metastatic BTC and support the clinically meaningful benefit of continued treatment with zanidatamab. The safety profile in all enrolled patients remained manageable with favorable tolerability compared with the initial analysis. Two (2.3%) patients discontinued treatment due to treatment-related adverse events (TRAEs).
The trial evaluated zanidatamab (20 mg/kg IV once every 2 weeks) in patients with HER2-positive, locally advanced unresectable, or metastatic BTC who had received prior gemcitabine-containing therapy. Patients with prior HER2-targeted therapy use were excluded from the trial. All patients were required to have centrally confirmed HER2-amplified tumors (assessed by in situ hybridization). Patients (n=87) were assigned into two cohorts based on tumor IHC status: Cohort 1 (n=80) included patients who were IHC 2+/3+ (HER2-positive) and Cohort 2 (n=7) included patients who were IHC 0/1+. The median duration of follow-up was 21.9 (16-34) months. Tumors were assessed every 8 weeks per RECIST v1.1. Updated efficacy analyses include only Cohort 1, while safety analyses include Cohorts 1 and 2.
As of July 28, 2023, data from HER2-positive BTC patients enrolled in Cohort 1 (n=80) demonstrated:
- With longer follow-up, the cORR was maintained from the initial analysis (n=33; 41.3%) (95% CI: 30.4, 52.8), with one additional complete response (n=2; 2.5%).
- Although the trial was not designed to detect treatment effects by HER2 status, as previously reported, in a pre-planned subgroup analysis of cORR by HER2 expression, responses were observed in patients with IHC 3+ tumors (cORR: 51.6% [95% CI: 38.6%-64.5%]) and IHC 2+ tumors (cORR: 5.6% [95% CI: 0.1-27.3%])2.
- A two-month increase in the median DoR to 14.9 months (95% CI: 7.4, not reached).
- In patients with IHC3+ tumors, the median DoR was 14.9 months (95% CI: 7.4, not reached).
- The DOR in the 1 responder with IHC 2+ tumors was 7.5 months.
- A median OS (95% CI) of 15.5 months (95% CI: 10.4, 18.5).
- The median OS in patients with IHC 3+ was 18.1 months (95% CI: 12.2, 23.2).
- The median OS in patients with IHC 2+ was 5.2 months (95% CI: 3.1, 10.2).
- Median progression-free survival (PFS) was maintained (5.5 months [95% CI: 3.6, 7.3]) compared with the initial analysis, which had a data cutoff of October 10, 2022.
- In patients with IHC 3+ tumors, the median PFS was 7.2 months (95% CI: 5.4, 9.4) months.
- In patients with IHC 2+ tumors, the median PFS was 1.7 months (95% CI: 1.0, 3.3) months.
As previously reported for Cohorts 1 and 2, zanidatamab demonstrated a manageable and tolerable safety profile, with no new safety signals identified and no deaths that were treatment related. TRAEs leading to dose reductions remained infrequent. Serious TRAEs occurred in eight (9.2%) patients. One patient experienced serious TRAEs since the initial analysis (alanine aminotransferase increased and aspartate aminotransferase increased).Treatment discontinuation rate was 2.3% and no additional patients discontinued treatment due to TRAEs since the initial analysis.
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