Ogivri is the first biosimilar of trastuzumab (Herceptin) to be approved for use in South Africa. Dr Ronwyn van Eeden unpacks why this is good news for HER2 positive breast cancer patients.
What is HER2?
Human epidermal growth factor receptor 2 (HER2) positive breast cancer accounts for about 20% of all breast cancers. HER2 is a protein situated on the surface of breast cells that promotes growth. When breast cells have higher than normal levels of HER2, a cancer develops.
HER2 positive breast cancers tend to grow faster and can also spread faster than other types of breast cancers. It’s mandatory that all breast cancers be tested for HER2 positivity, because these patients benefit greatly from a therapy that targets HER2, called trastuzumab.
How does trastuzumab work?
The development of trastuzumab has greatly changed the prognosis and survival of patients with HER2 positive breast cancer.
Trastuzumab is a drug, called a monoclonal antibody, that works by binding to the segment of HER2, which is outside of the breast cancer cell (HER2 receptor), and blocks other ligands (molecules which normally bind to the receptor and stimulates growth) from binding to it. Thus, prevents growth of cancer.
It can be used in combination with chemotherapy, endocrine therapy or on its own. Trastuzumab can be used for early-, locally advanced-, or metastatic breast cancer.
In early breast cancers, it can be curative. With larger breast tumours, it can also shrink the cancer significantly to allow the surgeon to operate safely and allow patients to have breast-conserving surgery if feasible. In metastatic cancers, it can make patients live longer. It increases overall survival in all these scenarios.
Trastuzumab can be given intravenously (through a drip or via a port into a vein) or subcutaneously (as an injection given underneath the skin). Both formulations are equal in efficacy.
How long do I need to be on trastuzumab for?
Trastuzumab can be used before surgery for a period to shrink tumours as determined by your oncologist.
After surgery, it’s given for one year. This is called adjuvant therapy (treatment given after surgery to decrease risk of relapse or recurrence).
There are trials (HERA, PHARE) that show that this is the correct and optimal duration. In the metastatic setting, it’s given until progression of cancer, or until the cancer develops resistance to trastuzumab.
Biosimilars are needed to reduce the cost of therapies for patients and make specialised therapies more widely accessible.
What is a biosimilar?
It’s a product, which is almost an identical copy of the original drug. There are usually no clinical meaningful differences in terms of the potency, purity and safety of the drug.
Biosimilars are officially approved versions of the original product and are usually implemented when the patent on an original drug expires.
Biosimilars are needed to reduce the cost of therapies for patients and make specialised therapies more widely accessible.
Numerous clinical trials that compare biosimilars to the original product are conducted before it can be registered for use.
The trials must convincingly demonstrate similarity between the two products, establishing efficacy, safety and that the biosimilar product is not inferior.
There are many trastuzumab biosimilars drugs approved around the world.
First trastuzumab biosimilar approved in South Africa
The introduction of a biosimilar of trastuzumab, called Ogivri, is planned for September. The drug is expected to be available, in South Africa, by October.
The efficacy of Ogivri, which is given intravenously, was established by a clinical trial (HERITAGE).
There are no details yet about the price and if medical aids will cover it. But, what we do know is that this drug broadens patient access.
A few more trastuzumab biosimilars should be registered for use in South Africa by the end of this year.
Currently, there is another trastuzumab biosimilar trial open at The Medical Oncology Centre of Rosebank.
Is trastuzumab available in the public setting?
The pharmaceutical company that manufactures the original product (Herceptin), developed a clone, called Herclon, which is available for use in the public setting.
A clone is the exact same drug, just with a different name and packaging.
Herclon was registered, in 2012, for both early and metastatic breast cancer.
However, in SA public setting, treatment with trastuzumab for HER2 positive breast cancer is only available in the adjuvant setting.
MEET OUR EXPERT – Dr Ronwyn van Eeden
Dr Ronwyn van Eeden is a medical oncologist at the Medical Oncology Centre of Rosebank. She has a special interest in supportive care in cancer and new anticancer agents, especially immunotherapy.