Poherdy (Pertuzumab-dpzb): The First “Interchangeable” Biosimilar for HER2-Positive Breast Cancer
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HER2-positive breast canceraccounts for approximately 15–20% of all breast cancers and, compared with other subtypes, may behave more aggressively. Drugs that directly target the HER2 receptor are therefore among the most critical components of treatment.
The US Food and Drug Administration (FDA) recently approved Poherdy (pertuzumab-dpzb) as Perjeta's (pertuzumab) first “interchangeable” biosimilar on November 13, 2025.
In practice, this decision means:
- Poherdy has the same effect as Perjeta.
- Its safety profile is the same.
- During treatment, Poherdy can replace Perjeta with your doctor's approval.
- Its price is expected to be lower , potentially reducing the financial burden, particularly for patients receiving prolonged treatment.
- More patients may gain access to lifesaving treatments .
Pertuzumab's Role in HER2-Positive Breast Cancer
In HER2-positive cancers, tumor cell surfaces contain far more HER2 receptors than normal . These receptors continuously signal the cell to “divide and proliferate,” which can cause faster tumor growth and spread.
Pertuzumab (Perjeta and Poherdy) prevents HER2 receptors from joining together and generating internal cancer growth signals; it is a monoclonal antibody. In brief:
- HER2 receptors' joining process, called dimerization, is disrupted, blocking cellular growth signals.
- Slows or stops cancer cell proliferation.
- Also helps the immune system recognize and destroy these cells (ADCC mechanism).
Pertuzumab is therefore a very important component of HER2-positive breast cancer treatment:
- Before surgery (neoadjuvant),
- After surgery (adjuvant),
- In metastatic disease
.
When Will Poherdy Be Used?
With FDA approval, Poherdy, has exactly the same indications as Perjeta .
1) Early-Stage HER2-Positive Breast Cancer
- Presurgical (neoadjuvant) treatment: Generally given with chemotherapy and trastuzumab.
- Postsurgical (adjuvant) treatment: Used with trastuzumab as a complementary component of treatment in high-risk patients.
2) Metastatic HER2-Positive Breast Cancer
- First-line treatment: Given with trastuzumab and docetaxel.
Poherdy's approved uses are summarized below:
| Setting | Clinical Stage | Combination Drugs | Goal |
|---|---|---|---|
| Neoadjuvant treatment | Early-stage HER2-positive | Trastuzumab + chemotherapy | Shrink the tumor, facilitate surgery |
| Adjuvant treatment | High-risk, after surgery | Trastuzumab | Reduce recurrence risk |
| First-line metastatic treatment | Metastatic HER2-positive | Trastuzumab + docetaxel | Improve survival and quality of life |
What Does “Interchangeable Biosimilar” Mean?
“Biosimilars” are biological products with very high similarity in structure, effect and safety to the reference biological drug (here, Perjeta), although they are not completely identical copies.
An “interchangeable” biosimilar goes a step further. For the FDA to grant this designation, Poherdy must demonstrate through scientific studies that:
- Its effect is fully equivalent to Perjeta's ,
- Its safety is exactly the same as Perjeta's ,
- During treatment, changing from Perjeta to Poherdy (switching) carries no additional risk or loss of efficacy
.
In practice, Poherdy can therefore be considered a fully equivalent alternative to Perjeta . If your doctor considers it appropriate, Poherdy may replace Perjeta during treatment without compromising patient safety.
Is Poherdy Safe? What Are Its Adverse Effects?
All studies conducted have shown that Poherdy's safety profile is exactly the same as Perjeta's . The expected adverse effects with Poherdy are therefore the same as Perjeta's in frequency and severity.
HER2-targeted treatments and accompanying chemotherapy can cause adverse effects. Most are manageable and temporary, although some require close monitoring.
Most Common Adverse Effects
| Adverse Effect | Description | Frequency |
|---|---|---|
| Diarrhea | May result from the drug itself and combination chemotherapy. Watch for fluid loss. | Common |
| Hair loss | Mainly caused by accompanying chemotherapy (e.g., docetaxel). | Moderate |
| Fatigue | May result from both the cancer itself and the combined adverse effects of treatment. | Moderate |
| Neutropenia (low white blood cell count) | May be more pronounced with docetaxel. May increase infection risk. | Moderate |
| Reduced cardiac function | A rare but important adverse effect that can occur with trastuzumab and pertuzumab. Regular cardiac ultrasound (echocardiography) monitoring is required. | Low–Moderate |
Important Note: As with Perjeta, cardiac function must be assessed regularly during Poherdy treatment. Your doctor may therefore request periodic ECGs and particularly echocardiography tests.
Clinical Study Summary
FDA approval is not based merely on a simple judgment that it “looks similar.” Poherdy passed a multilayered approval process, summarized under four headings:
A) Analytical (Laboratory) Similarity Tests
These tests demonstrate Poherdy's structural similarity to Perjeta. Studies showed that:
- The amino acid sequence is identical,
- The antibody's three-dimensional structure is equivalent,
- HER2 receptor binding strength and binding pattern are the same,
- The capacity to inhibit HER2 dimerization is equivalent,
- The glycosylation (sugar attachments) profile is consistent
. This stage forms the foundation of biosimilar approval.
B) Clinical Pharmacokinetic Study (PK)
Pharmacokinetics concerns how a drug behaves in the body. For Poherdy and Perjeta, these studies compared:
- Maximum blood concentration (Cmax)
- Total exposure (AUC0–∞, AUC0–t)
- Half-life and elimination rate
and demonstrated complete equivalence .
C) Clinical Efficacy Study
Efficacy assessments examined, particularly for presurgical treatment, pathological complete response (pCR) rates. A pathological complete response means no viable tumor cells remain in tissue removed at surgery and is an important indicator of long-term outcomes.
| Outcome Evaluated | Poherdy | Perjeta | Assessment |
|---|---|---|---|
| pCR (pathological complete response) rate | Within equivalent range | Within equivalent range | No clinically meaningful difference |
| Serious adverse event rate | Similar | Similar | Equivalent safety profile |
| Impaired cardiac function | Rare, low rate | Rare, low rate | The same monitoring protocol is sufficient |
D) Interchangeability (“Switching”) Study
For the “interchangeable” designation, switching , meaning changing from Perjeta to Poherdy during treatment, was specifically examined. In these studies, some patients:
- Started treatment with Perjeta and later switched to Poherdy.
- After switching, they were monitored for any adverse change in efficacy or adverse effects.
| Parameter Examined | Switching Outcome |
|---|---|
| Adverse effect frequency | Same as groups continuing Perjeta |
| Treatment efficacy (response rate) | No loss or reduction observed |
| Immunogenicity (does the body recognize the drug as foreign?) | No additional risk identified; the same level as the reference product |
These data led the FDA to grant Poherdy not only biosimilar status but also “interchangeable” status.
Practical Implications for Patients
✔ Easier Access
Targeted treatments are costly drugs. Introducing biosimilars such as Poherdy makes it possible to:
- Provide access for more patients worldwide,
- Use resources more efficiently
.
✔ Lower Cost
Poherdy is expected to cost less than Perjeta. This could offer major advantages to individual patients and healthcare systems. In some countries, these savings will allow more patients to receive treatment .
✔ Your Treatment Remains the Same
Poherdy is identical to Perjeta in mechanism, indications, dosing and administration. In the treatment schedule:
- Drug administration days,
- Required assessments,
- Adverse effect monitoring
continue in the same way.
✔ Switching Without Interrupting Treatment
Switching studies have shown that changing from Perjeta to Poherdy midway through treatment carries no additional risk . Your doctor may therefore make this change during treatment if appropriate.
Will Poherdy Come to Turkey?
At present, Poherdy has received FDA approval in the USA.
In practice, biosimilars of this kind are generally considered for entry into Turkey within 1–2 years after FDA or EMA approval. This timeframe is not fixed and depends on company strategies and local regulations.
There is currently no pertuzumab biosimilar in Turkey; only Perjeta (pertuzumab) is reimbursed. Following FDA approval, Poherdy or other pertuzumab biosimilars may be expected to apply in Turkey in the coming years.
Patients' Most Frequently Asked Questions
1. Is Poherdy weaker than Perjeta?
No. Poherdy was developed to have the same potency as Perjeta , and this equivalence has been demonstrated in clinical studies.
2. Will I feel a difference between the drugs?
No. Clinical studies found no significant difference between patients receiving Poherdy and Perjeta in:
- Adverse effects,
- Effects on daily life,
- Effects on the heart and other organs
.
3. Can I switch to Poherdy midway through treatment?
Yes. The FDA specifically examined this through switching studies and demonstrated that changing from Perjeta to Poherdy midway through treatment causes no additional risk or loss of efficacy . Nevertheless, this change must always be made by decision of the oncologist overseeing your treatment .
4. Will my adverse effects increase if I switch to Poherdy?
No. Because the safety profiles are identical, an increase in adverse effects is not expected after switching. Every patient's body is different, of course, so your doctor should continue to monitor and manage all adverse effects.
5. When Will It Be Available in Turkey?
Biosimilars of this kind may generally be considered in Turkey within 1–2 years after FDA or EMA approval, although this may take less or more time.
A New Era in Breast Cancer Treatment
Approval of Poherdy as Perjeta's first “interchangeable” biosimilar for HER2-positive breast cancer is a major development for oncology practice worldwide.
This approval makes it more feasible to achieve:
- Access to targeted treatments for a broader patient population,
- A reduced financial burden on healthcare systems,
- For patients receiving long-term treatment, a more sustainable financial framework
.
Targeted agents have transformed HER2-positive breast cancer treatment over the past 20 years. The introduction of a pertuzumab biosimilar adds a new chapter in access and sustainability to this success story.
The most appropriate treatment plan for each patient must be determined with individual characteristics, tumor biology and living circumstances in mind by the oncology team. Scientific evidence and health policies in the coming years will shape the place of Poherdy and other biosimilars in that plan.
References
- U.S. Food and Drug Administration (FDA). “FDA Approves Poherdy (pertuzumab-dpzb) as an Interchangeable Biosimilar to Perjeta.” FDA Center for Drug Evaluation and Research, 2025.
- FDA Purple Book Database. “Pertuzumab-dpzb (Poherdy) – Interchangeable Biosimilar Status Record.” Updated 2025.
- FDA Guidance for Industry. “Considerations in Demonstrating Interchangeability With a Reference Product.” U.S. Department of Health and Human Services.
- Genentech / Roche. “Perjeta (Pertuzumab) Prescribing Information.” Revised 2024–2025.
- European Medicines Agency (EMA). “Perjeta – European Public Assessment Report (EPAR).” EMA, 2024.
- ClinicalTrials.gov. “Study of Pertuzumab-dpzb vs Pertuzumab: Pharmacokinetics and Clinical Equivalence Trials.” Accessed 2025.
- Analytical Similarity Assessment Reports for Pertuzumab-dpzb. Manufacturer public submission summary to FDA (2025).
- Switching Study Data Package. “Pertuzumab-dpzb Interchangeability Demonstration.” FDA Submission Data, 2025.
- NCCN Clinical Practice Guidelines in Oncology – Breast Cancer v.2025. National Comprehensive Cancer Network.
- European Society for Medical Oncology (ESMO). “ESMO Clinical Practice Guidelines – HER2-Positive Breast Cancer.” 2024–2025 Update.
- American Society of Clinical Oncology (ASCO). “Systemic Therapy for HER2-Positive Metastatic Breast Cancer.” J Clin Oncol. 2024.
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