RegulatoryCompany release

Xencor selects 400 mcg/kg IV dose of XmAb819 for Phase 3 in kidney cancer

🇺🇸 Xencor Inc (XNCR) · Mon 26 Oct 2026

Updated Phase 1 data show a 45.5% confirmed response rate in 11 evaluable patients, alongside a high rate of serious related adverse events and three suspected dose preparation errors.

Xencor has chosen 400 mcg/kg given intravenously as the proposed Phase 3 dose of XmAb819, its ENPP3 x CD3 bispecific T-cell engager for advanced clear cell renal cell carcinoma. The decision follows updated Phase 1 results presented at ESMO 2026 on 25 October.

Among 11 evaluable patients, the confirmed response rate was 45.5%. The small evaluable population means the figure should be read with caution.

On safety, grade 3 or higher treatment-related adverse events occurred in 72.1% of patients treated at the expansion dose. The events were mainly liver enzyme elevations, rash and cytokine release syndrome, a known class effect of T-cell engagers.

The company also reported three suspected dose preparation errors. These preceded the introduction of a new formulation. The summary does not say what the errors involved or how the new formulation addresses them.

Xencor plans to discuss a possible accelerated approval pathway with the US Food and Drug Administration in the first half of 2027. It also intends to start a global randomised study comparing XmAb819 with tivozanib.

What it means for your team

  • Regulatory teams should watch the FDA discussions planned for 1H 2027, which will show whether an accelerated approval route based on a small Phase 1 dataset is viable.
  • Pharmacovigilance teams should note the 72.1% rate of grade 3 or higher related events, including cytokine release syndrome and liver enzyme elevations, as a benchmark for T-cell engager risk management.
  • Quality and medication-safety teams should note that suspected dose preparation errors led to a reformulation, a reminder that handling complexity can affect clinical safety.
  • Market-access teams can expect a randomised comparison with tivozanib to be the main source of comparative evidence.

Company's press release (SEC filing): Xencor Inc ↗

Article written by VigiEye from the official source (Xencor Inc). Claims are the company's own. AI-assisted; check the source before acting.

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