Zanidatamab for HER2-amplified, unresectable, locally advanced or metastatic biliary tract cancer (HERIZON-BTC-01): a multicentre, single-arm, phase 2b study.

BACKGROUND: HER2 is overexpressed or amplified in a subset of biliary tract cancer. Zanidatamab, a bispecific antibody targeting two distinct HER2 epitopes, exhibited tolerability and preliminary anti-tumour activity in HER2-expressing or HER2 (also known as ERBB2)-amplified treatment-refractory biliary tract cancer. METHODS: HERIZON-BTC-01 is a global, multicentre, single-arm, phase 2b trial of zanidatamab in patients with HER2-amplified, unresectable, locally advanced, or metastatic biliary tract cancer with disease progression on previous gemcitabine-based therapy, recruited at 32 clinical trial sites in nine countries in North America, South America, Asia, and Europe. Eligible patients were aged 18 years or older with HER2-amplified biliary tract cancer confirmed by in-situ hybridisation per central testing, at least one measurable target lesion per Response Evaluation Criteria in Solid Tumours (version 1.1), and an Eastern Cooperative Oncology Group performance status of 0 or 1. Patients were assigned into cohorts based on HER2 immunohistochemistry (IHC) score: cohort 1 (IHC 2+ or 3+; HER2-positive) and cohort 2 (IHC 0 or 1+). Patients received zanidatamab 20 mg/kg intravenously every 2 weeks. The primary endpoint was confirmed objective response rate in cohort 1 as assessed by independent central review. Anti-tumour activity and safety were assessed in all participants who received any dose of zanidatamab. This trial is registered with ClinicalTrials.gov, NCT04466891, is ongoing, and is closed to recruitment. FINDINGS: Between Sept 15, 2020, and March 16, 2022, 87 patients were enrolled in HERIZON-BTC-01: 80 in cohort 1 (45 [56%] were female and 35 [44%] were male; 52 [65%] were Asian; median age was 64 years [IQR 58-70]) and seven in cohort 2 (five [71%] were male and two [29%] were female; five [71%] were Asian; median age was 62 years [IQR 58-77]). At the time of the data cutoff (Oct 10, 2022), 18 (21%) patients (17 in cohort 1 and one in cohort 2) were continuing to receive zanidatamab; 69 (79%) discontinued treatment (radiographic progression in 64 [74%] patients). The median duration of follow-up was 12·4 months (IQR 9·4-17·2). Confirmed objective responses by independent central review were observed in 33 patients in cohort 1 (41·3% [95% CI 30·4-52·8]). 16 (18%) patients had grade 3 treatment-related adverse events; the most common were diarrhoea (four [5%] patients) and decreased ejection fraction (three [3%] patients). There were no grade 4 treatment-related adverse events and no treatment-related deaths. INTERPRETATION: Zanidatamab demonstrated meaningful clinical benefit with a manageable safety profile in patients with treatment-refractory, HER2-positive biliary tract cancer. These results support the potential of zanidatamab as a future treatment option in HER2-positive biliary tract cancer. FUNDING: Zymeworks, Jazz, and BeiGene.

Functional characterization of uveal melanoma oncogenes.

Uveal melanoma (UM) is a currently untreatable form of melanoma with a 50% mortality rate. Characterization of the essential signaling pathways driving this cancer is critical to develop target therapies. Activating mutations in the Gαq signaling pathway at the level of GNAQ, GNA11, or rarely CYSLTR2 or PLCß4 are considered alterations driving proliferation in UM and several other neoplastic disorders. Here, we systematically examined the oncogenic signaling output of various mutations recurrently identified in human tumors. We demonstrate that CYSLTR2 → GNAQ/11 → PLCß act in a linear signaling cascade that, via protein kinase C (PKC), activates in parallel the MAP-kinase and FAK/Yes-associated protein pathways. Using genetic ablation and pharmacological inhibition, we show that the PKC/RasGRP3/MAPK signaling branch is the essential component that drives the proliferation of UM. Only inhibition of the MAPK branch but not the FAK branch synergizes with inhibition of the proximal cascade, providing a blueprint for combination therapy. All oncogenic signaling could be extinguished by the novel GNAQ/11 inhibitor YM-254890, in all UM cells with driver mutation in the Gαq subunit or the upstream receptor. Our findings highlight the GNAQ/11 → PLCß â†’ PKC → MAPK pathway as the central signaling axis to be suppressed pharmacologically to treat for neoplastic disorders with Gαq pathway mutations.