On May 1, 2026, the U.S. Food and Drug Administration officially approved Vepdegestrant (trade name: Veppanu) for the treatment of adult patients with estrogen receptor–positive (ER+), human epidermal growth factor receptor 2–negative (HER2−), ESR1-mutant advanced or metastatic breast cancer, whose disease has progressed after at least one line of endocrine therapy.

This milestone not only marks the launch of a new drug but also signifies the transition of targeted protein degradation from a scientific concept to real-world clinical application, emerging as a new therapeutic paradigm alongside small molecules and antibody-based therapies.

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1. From “Inhibition” to “Degradation”: A Paradigm Shift in Mechanism

Traditional drug development has largely focused on occupancy-driven inhibition—binding to target proteins to block their function. However, this approach has inherent limitations:

• Requires sustained high drug concentrations
• Prone to resistance, especially in mutated proteins
• Limited ability to address “undruggable” targets

PROTAC technology offers a fundamentally different solution. These are bifunctional molecules: one end binds to the target protein, while the other recruits an E3 ubiquitin ligase, triggering the cell’s ubiquitin–proteasome system to label and degrade the target protein.

👉 Key distinction:

• Inhibition = renders the protein inactive
• Degradation = removes the protein entirely from the cell

This event-driven mechanism allows PROTACs to achieve sustained efficacy at lower doses and may significantly reduce the risk of drug resistance.

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2. Focus on Breast Cancer: Addressing ESR1 Mutation–Driven Resistance

Vepdegestrant is indicated for ER-positive, HER2-negative advanced breast cancer patients harboring ESR1 mutations.

The pivotal VERITAC-2 (NCT05654623) study is a randomized, open-label, active-controlled, multicenter trial enrolling 624 adult patients with ER+/HER2− advanced or metastatic breast cancer, including 270 patients with ESR1-mutant tumors. All participants had received one to two prior lines of endocrine therapy, including a CDK4/6 inhibitor, and experienced disease progression.

In clinical practice, ESR1 mutations are a major driver of endocrine resistance. Conventional therapies such as Fulvestrant offer partial degradation of the estrogen receptor but have limited efficacy against mutant forms.

In contrast, PROTACs directly degrade the estrogen receptor (ER) protein itself, effectively shutting down oncogenic signaling at its source. Clinical data demonstrate improved progression-free survival (PFS) compared with standard therapies, offering a new option for patients with resistant disease.

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3. Why Is This a “Milestone”?

1️⃣ From Lab Concept to Commercial Reality

After nearly two decades of development, PROTAC technology has overcome early challenges such as molecular design complexity and suboptimal pharmacokinetics, achieving oral bioavailability and clinical validation.

2️⃣ Redefining Drug Discovery Logic

Traditional druggable targets are limited to proteins with well-defined binding pockets. PROTACs leverage the cell’s degradation machinery, opening new possibilities for previously “undruggable” targets.

3️⃣ Evolution of Therapeutic Modalities

From small-molecule inhibitors and monoclonal antibodies to antibody-drug conjugates (ADCs), cancer therapy has continuously evolved. The success of PROTACs establishes targeted protein degradation as a distinct and highly promising therapeutic platform.

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4. Safety Profile of Vepdegestrant

Safety data presented at the American Society of Clinical Oncology (ASCO) Annual Meeting 2025 showed:

• Any-grade treatment-emergent adverse events (TEAEs):
  • 87% (vepdegestrant, n=312)
  • 81% (fulvestrant, n=307)
• Grade ≥3 TEAEs:
  • 23% vs. 18%
• Serious TEAEs:
  • 10% vs. 9%

TEAEs led to treatment discontinuation in 3% of patients in the vepdegestrant group versus 1% in the fulvestrant group. Dose reductions occurred in 2% of patients receiving vepdegestrant.

Treatment-related adverse events (TRAEs) were reported in 57% of patients receiving vepdegestrant compared with 40% in the fulvestrant group. Grade ≥3 TRAEs occurred in 8% and 3% of patients, respectively.

The most common adverse events (≥10%) included:

• Fatigue (27% vs. 16%)
• Increased ALT (14% vs. 10%)
• Increased AST (14% vs. 10%)
• Nausea (13% vs. 9%)
• Anemia (12% vs. 8%)
• Neutropenia (12% vs. 5%)
• Back pain (11% vs. 7%)
• Arthralgia (11% vs. 11%)
• Decreased appetite (11% vs. 5%)

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5. Industry Momentum: The Expanding PROTAC Landscape

With the first approval achieved, global PROTAC development is accelerating:

• Multiple targets (e.g., AR, BTK, KRAS) are advancing in clinical trials
• Increasing investment from multinational pharmaceutical and biotech companies
• Rapid pipeline expansion among Chinese innovative pharma companies

This trend underscores that PROTAC is not just a single-product success, but the rise of a platform technology with broad therapeutic potential.

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Conclusion

The launch of the world’s first PROTAC drug is more than just an approval; it represents a significant turning point in drug development philosophy. From “blocking function” to “eliminating the root cause,” protein degradation therapy offers humanity a novel tool to combat complex diseases.

Looking to the future, as this technology continues to expand its applications and accelerates its integration with cutting-edge fields such as cell therapy and gene editing, the global healthcare system will undergo a more efficient and precise transformation. In this process, DengYueMed continues to focus on the global distribution and supply chain optimization of innovative drugs, committed to breaking down barriers to cross-border medical resources and enabling cutting-edge therapies, including PROTACs, to reach clinicians and patients more quickly.