New breast cancer drug shows ‘remarkable results’

Trial on hundreds shows it helps prolong survival for those with advanced breast cancer

DUBAI: Cancer is an illness of devilish complexity. In recent years, the tools available to mankind against the dreaded disease has greatly improved.

Now, there’s a potentially major medical breakthrough involving a monoclonal antibody-chemotherapy combo, also known as an antibody-drug conjugate (ADC).

The drug, called trastuzumab deruxtecan (brand: Enhertu), has shown huge improvements in “progression-free survival” for a subset of breast cancer patients.

When the study was presented at a recent annual meeting of oncologists, cancer specialists gave the research team a standing ovation. Results were dubbed “remarkable”.

Specifically, the clinical trial conducted on 557 advanced breast cancer patients showed that the antibody-drug combo helped prolong the patients' life expectancy.

What we know so far:

What is the breast cancer drug called?

It is called trastuzumab deruxtecan (Enhertu), a combination of existing drugs.

Is it a new drug?

Enhertu is not a new drug. It is already approved in patients with HER2-positive breast cancer.

Is it a cure for cancer?

No. The study focussed on a narrow subset of breast cancer patients — 557 women who had advanced forms of a specific type of what is known as metastatic HER2-low breast cancer.

HER2 refers to the human epidermal growth factor receptor-2, a protein known to promote cancer cell growth.

HER2-low metastatic breast cancer refers to low levels of HER2 receptor detected in the patients — for whom there weren’t a lot of treatment options available today.

HER2-low affects about 50 to 55 per cent of all primary breast cancers.

How does trastuzumab Deruxtecan work?

Trastuzumab attaches to the HER2 proteins, and can stop the cancer cells growing, the website breastcancernow.org explained. It also helps the body’s immune system destroy cancer cells. When the trastuzumab attaches to the cancer proteins, it delivers deruxtecan — directly into the breast cancer cells to kill them.

How does the drug’s so-called 'bystander effect' work?

Trastuzumab deruxtecan also has a “bystander effect”. Erika P. Hamilton, MD, director of the Breast Cancer and Gynecologic Cancer Research Program and principal investigator at the Sarah Cannon Research Institute, explained in an onclive.com session that cancer data on the use of trastuzumab deruxtecan in HER2-low–expressing breast cancers is building up.

She explained the ADC’s a unique mechanism of action — the molecule’s “bystander effect” — in which even if a small amount of trastuzumab deruxtecan "binds", it can kill neighbouring cells that may not have much HER2 expression at all.

What’s with the use of monoclonal antibodies in cancer treatment?

It’s an exciting field, say doctors. The use of monoclonal antibodies in cancer treatment is not new. The first monoclonal antibody was generated in 1975, but it was only fully licensed in 1986 — aided by breakthroughs in medical science.

However, the development represents a new way in which to target specific mutations and defects in protein structure and expression in a wide range of diseases and conditions.

How did the trial volunteers respond to the treatment?

Among patients with advanced metastatic HER2-low cancers, the trial showed that Enhertu led to patients able to live longer — up to six months— when administrated with ADC compared to those on the placebo group with standard chemotherapy.

How common is breast cancer?

It is fairly common.

“Forty (40) per cent of women develop cancer in their lifetime and 1 out of 3 of this is breast cancer,” according to Dr Eugene Rent, surgical oncologist at NMC Specialty Hospital, Al Nahda, Dubai, told Gulf News.

“That’s how common it is and that’s why we need to tackle this disease.”

What are the most common breast cancer treatments?

The standard treatments for breast cancer include chemotherapy, radiation, hormonal therapy and, recently, targeted therapy. Targeted therapy is used for advanced or metastatic breast cancer, of which ADC is currently under investigation, or being considered for regulatory approval.

What’s new with the study?

Some patients with metastatic tumours not significantly helped by treatments such as chemotherapy, had seen their cancer’s growth halted. Patients treated with the new ADC survived for 23.9 months, researchers stated.

How will it change the way breast cancer is treated?

In general, cancer specialists said the new development could “change” how medicine was practiced. But a bigger study is needed to validate the initial findings.

When will the new drug be available or approved?

It’s not known at the moment when it will be approved for HER2-low metastatic cancer. US media reported Enhertu has been granted by the Food and Drug Administration (FDA) an “expedited breakthrough” designation — which could potentially speed up the approval timeline for HER2-low breast cancer patients.

What is the cost of the medicine?

Enhertu comes with a huge price tag: about $14,000 a month, according to science media. Doctors say cost is a challenge for the pharma, research community, insurers and society as a whole to work on together.

“We need to go for further, (with a) detailed study to see better survival. At this stage, it looks promising to me. Side effects of chemotherapy are comparatively more than this drug, except lung toxicity is found more in this drug,” said Dr Pranay Taori, UAE-based oncologist at Aster Group.

“If it becomes a standard of care, definitely, it is a very good ray of hope for the patients who have advanced metastatic cancer, who are expressing low HER, where chemotherapy has failed and where the patient cannot tolerate chemotherapy,” said Dr Taori, who congratulated the researchers who contributed to the study.