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Ado-trastuzumab emtansine effective, safe in HER2-amplified salivary gland cancers
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CHICAGO — Ado-trastuzumab emtansine appeared highly effective and safe among patients with HER2-amplified salivary gland cancers, according to results of a phase 2 study presented at ASCO Annual Meeting.
“Salivary gland cancers are very curious and account for only 0.8% of all cancers,” Bob T. Li, MD, MPH, medical oncologist at Memorial Sloan Kettering Cancer Center, said during the presentation. “There is no approved therapy for metastatic disease, and because of their rarity, there is no standard of care.”
About 8% of all salivary gland cancers feature HER2 amplification, which occurs in 25% to 33% of the aggressive salivary duct carcinoma subtype.
Li and colleagues assigned ado-trastuzumab emtansine (Kadcyla, Genentech), a HER2-targeted antibody-drug conjugate, to 10 patients with HER2-amplified salivary gland cancers (median age, 65 years; range, 36-90; 90% men).
Patients underwent a median of two previous systemic lines of therapy (range, 0-3). Investigators used next-generation sequencing to identify HER2 amplification, and later tested tumors by fluorescence in situ hybridization and immunohistochemistry.
Overall response rate served as the primary endpoint. PFS, OS, duration of response and toxicity served as secondary endpoints.
Median follow up was 12 months (range, 4-20).
Results showed an ORR of 90% (95% CI, 56-100) that included five complete responses after prior trastuzumab (Herceptin, Genentech), pertuzumab (Perjeta, Genentech) and antiandrogen therapy.
Median duration of response (range, 2-19+ months) and median PFS (95% CI, 4-22+ months) were not reached.
Common toxicities included grade 1 or grade 2 infusion reactions, thrombocytopenia and transaminitis.
No patients died as a result of treatment.
Researchers observed correlations of HER2 amplification by next-generation sequencing (fold change, 2.8-22.8) with HER2/CEP172 by fluorescence in situ hybridization (8 of 8 tested) or IHC3+ (10 of 10 tested).
“Ado-trastuzumab emtansine is highly efficacious in patients with HER2-amplified salivary gland cancers as identified by next-generation sequencing,” Li said. “We are reporting this study early because it already met its primary endpoint, and cohort expansion is warranted to confirm these results.”– by John DeRosier
Reference:
Li BT, et al. Abstract 6001. Presented at: ASCO Annual Meeting; May 31- June 4, 2019; Chicago.
Disclosures: Li reports consultant/advisory roles with Biosceptre International, Guardant Health, Hengrui Therapeutics, Mersana, Roche and Thermo Fisher Scientific and research funding from AstraZeneca, BioMed Valley Discoveries, Daiichi Sankyo, GRAIL, Guardant Health, Hengrui Therapeutics, Illumina and Roche/Genentech. Please see the abstract for all other authors’ relevant financial disclosures.