A phase 2 basket trial of combination therapy with trastuzumab and pertuzumab in patients with solid cancers harboring HER2 amplification (JUPITER trial)

TPS3141 Background: The human epidermal growth factor receptor 2 (HER2) gene amplification and mutations have emerged as oncogenic drivers and therapeutic targets not limited to breast and gastric cancers, but also in a variety of cancers. However, even if an actionable gene alteration is found, the incidence of HER2 amplification in these cancers is less than 5%. Despite its considerable therapeutic potential, the evidence is not yet mature enough for use as treatment in clinical practice. To address this unmet clinical need, we have designed an organ-agnostic basket trial, which covers a variety of solid cancers harboring HER2 amplification. Methods: JUPITER trial is a Japanese multicenter, single-arm, phase 2 basket study of combination therapy with trastuzumab and pertuzumab. Patients with solid cancers harboring HER2 amplification, who have progressed with standard treatment, or rare cancers for which there is no standard treatment, are eligible. Types of cancer include bile duct, urothelial, uterine, ovarian, and other solid cancers that HER2 amplification is detected by comprehensive genomic profiling using next-generation sequencing technology. Target sample size is 38. All enrolled patients receive combination therapy with trastuzumab and pertuzumab every 3 weeks until disease progression, unacceptable toxicity, death, or withdrawal of informed consent. Response assessment using RECIST version 1.1 is performed at weeks 9 and 17, followed by every 12 weeks. The primary endpoint is the objective response rate, and secondary endpoints are progression-free survival, overall survival, duration of response, and safety. In total, 40 patients were enrolled by June 2020. Data fix is scheduled in September 2021. Trial registration: jRCT2031180150 Clinical trial information: jRCT2031180150.