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JSKN016-101 — JSKN016 (TROP2/HER3 bispecific ADC), HER2-negative advanced/metastatic breast cancer, late-line

Abstract: 1123 · Session: Breast Cancer—Metastatic, Poster Session (June 1, 2026, 1:30–4:30 PM CT) · Presenter: Herui Yao, Sun Yat-sen Memorial Hospital, Sun Yat-sen University · Embargo: Jun 1, 2026

At a glance

  • Sponsor: Alphamab Oncology (9966.HK)
  • PI / presenter: Herui Yao (Sun Yat-sen Memorial Hospital, Sun Yat-sen University)
  • NCT ID: NCT06592417
  • Phase: Phase I (dose-escalation / dose-expansion, China)
  • Design: First-in-human, open-label monotherapy study in advanced solid tumors; ASCO 2026 reports the HER2-negative locally advanced/metastatic breast cancer cohort (incl. mTNBC and HR+/HER2- BC)
  • N: HER2-negative BC cohort (exact N not disclosed in pre-meeting topline)
  • Primary endpoint(s): Safety/tolerability, MTD/RP2D; preliminary antitumor activity (ORR, DCR per RECIST v1.1)
  • Comparator: None (single-arm)
  • Indication: HER2-negative (incl. triple-negative) locally advanced or metastatic breast cancer
  • Line: Heavily pretreated / late-line (multiple prior lines)

Headline result

Per Alphamab Oncology pre-meeting topline (Apr 23, 2026), no quantitative cohort-level efficacy was released for abstract 1123; the company states JSKN016 showed "very promising efficacy and superior safety profile in late-line BC patients." Prior first-in-human data for the same program — presented at ASCO 2025 (mTNBC subset) — reported a preliminary ORR of 80% (4 PR, 1 SD among 5 efficacy-evaluable mTNBC pts) with no cardiac toxicity, no CRS, no treatment-related ILD, and no AE-related discontinuations or deaths within the studied dose. The ASCO 2026 poster expands these observations to the broader HER2-negative cohort; presented numbers (ORR/DCR/N/safety) should be read off the abstract 1123 poster on Jun 1 rather than from press releases.

Mechanism / class

First-in-class TROP2/HER3 bispecific antibody-drug conjugate. Built on Alphamab's single-domain + bispecific antibody platforms; site-specific glycosylation conjugation yields a homogeneous, stable ADC with DAR 4 carrying a topoisomerase I inhibitor payload. Dual TROP2 and/or HER3 binding is intended to broaden tumor targeting and widen the therapeutic window vs single-target TROP2 ADCs. No marketed approvals; a Phase III study in TNBC is ongoing (first patient dosed reported 2025/2026).

Practice-changing?

Pending. Early-phase, single-arm, China-only, small HER2-negative cohort with no quantitative ASCO 2026 topline yet public. Of interest as a first-in-class dual-target ADC in a field crowded by single-target TROP2 ADCs (sacituzumab govitecan, datopotamab deruxtecan), but Phase III randomized data are required before any practice impact.

Sources

  • ASCO Meeting Library (abstract 1123, ASCO 2026): https://www.asco.org/abstracts-presentations
  • Alphamab Oncology / PR Newswire (2026 ASCO preview, Apr 23, 2026): https://www.prnewswire.com/apac/news-releases/2026-asco-preview--alphamab-oncology-to-present-clinical-data-of-trop2her3-bispecific-adc-jskn016-for-her2-negative-breast-cancer-302751080.html
  • BioPharm International (Apr 2026): https://www.biopharminternational.com/view/alphamab-oncology-to-present-phase-1-data-on-bispecific-adc-jskn016-in-her2-negative-breast-cancer-at-asco-2026
  • Alphamab Oncology newsroom: https://www.alphamabonc.com/en/html/news/2785.html
  • Prior data (ASCO 2025 first-in-human mTNBC, abstract): https://www.asco.org/abstracts-presentations/250129