Next-Generation HER2-Targeted ADCs Show Promise in Breast Cancer Trials
核心洞察
TQB2102, a bispecific HER2 (搜索)-directed antibody-drug conjugate, achieved a 76.9% pathologic complete response rate in neoadjuvant treatment of HER2-positive breast cancer (搜索) patients.
The phase 2 trial demonstrated that 8 cycles of TQB2102 at 6.0 mg/kg every 3 weeks was superior to 6-cycle regimens, with manageable safety profile.
ARX788, another next-generation ADC, is entering phase 2 trials for HER2-low breast cancer (搜索) patients, targeting an underserved population with high unmet medical need.
Two next-generation antibody-drug conjugates (ADCs) targeting HER2 (搜索) are demonstrating significant clinical potential in breast cancer treatment, with TQB2102 showing exceptional efficacy in HER2-positive disease and ARX788 preparing to address the underserved HER2-low population.
TQB2102 Achieves High Response Rates in Neoadjuvant Setting
The bispecific HER2 (搜索)-directed ADC TQB2102 has demonstrated robust antitumor activity in the phase 2 TQB2102-II-01 trial, with the optimal dosing regimen achieving a 76.9% total pathologic complete response (tpCR) rate. The randomized, open-label, multicenter trial conducted in China enrolled 104 patients with HER2-positive stage II or III breast cancer between February 5, 2024, and September 24, 2024.
Patients were randomly assigned across four cohorts receiving different TQB2102 dosing regimens via intravenous infusion. Cohort 2, which received 6.0 mg/kg once every 3 weeks for 8 cycles, exhibited the highest tpCR rate at 76.9% (90% CI, 62.3%-87.6%; P <.01). The other cohorts achieved tpCR rates of 57.7%, 61.5%, and 69.2% for cohorts 1, 3, and 4, respectively.
"As a bispecific HER2 (搜索)-directed ADC, TQB2102 can recognize the HER2 protein by binding to both the trastuzumab [Herceptin] and pertuzumab [Perjeta] binding sites," the study authors noted. "To our knowledge, our study was the first to reveal that [8] cycles of single-agent TQB2102 could achieve a pCR rate of 73.1% in HER2[+] patients with [breast] cancer, which was numerically superior to the pCR rates of other ADCs and those of standard chemotherapy plus trastuzumab and pertuzumab reported in other previous trials."
Favorable Safety Profile Supports Clinical Development
TQB2102 demonstrated a manageable safety profile across all dosing cohorts, with no treatment-related deaths reported. The incidence rates of grade 3 or higher treatment-related adverse events were 23.1%, 30.8%, 30.8%, and 26.9% for cohorts 1, 2, 3, and 4, respectively, with an overall incidence rate of 27.9%. One case of interstitial lung disease occurred in cohort 4.
The superior efficacy of the 8-cycle regimen has prompted initiation of a larger randomized phase 3 trial (NCT07043725) evaluating TQB2102 against the standard combination of trastuzumab, pertuzumab, and chemotherapy in patients with HER2-positive breast cancer (搜索).
ARX788 Targets HER2-Low Population
Meanwhile, ARX788, another next-generation site-specific ADC, is preparing to enter phase 2 evaluation for HER2-low breast cancer (搜索) patients. This population, defined as HER2 (搜索) IHC 1+ or 2+ and FISH/ISH negative, represents a significant unmet medical need with limited treatment options.
ARX788 features a monoclonal antibody targeting HER2 (搜索), conjugated via a specialized non-natural amino acid linker to AS269, a potent tubulin (搜索) inhibitor payload. While previous phase 1 studies (ACE-Breast-01 and ACE-Pan Tumor-01) demonstrated efficacy in HER2-positive cases, they also identified associated ocular adverse events.
Addressing Safety Concerns in HER2-Low Setting
The upcoming single-arm, open-label phase 2 clinical trial (NCT06224673) will evaluate ARX788's safety and efficacy as monotherapy for patients with locally advanced unresectable or metastatic breast cancer (搜索) who have received at least one prior line of chemotherapy or ADC therapy. Patients will receive ARX788 intravenously at 1.5 mg/kg every 2 weeks until disease progression or intolerable toxicity.
Enrollment, beginning in the third quarter of 2025, aims to recruit 30 to 36 patients divided into two cohorts: HR-positive/HER2 (搜索)-low (n = 20-24) and HR-negative/HER2-low (n = 10-12). The primary endpoint is objective response rate, with the sample size powered to estimate ORR with specific margin of error at 90% confidence level, anticipating a 25% response rate.
Secondary endpoints include duration of response, disease control rate, progression-free survival, overall survival, and importantly, the efficacy of a prophylactic regimen designed to prevent grade 2 or higher ocular toxicity. This addresses the adverse effects noted in phase 1 studies and represents a key safety consideration for the HER2 (搜索)-low population.