Breast cancer | A promising new drug is gaining attention

A new drug against breast cancer raises a lot of hope. Designed in Japan, Enhertu was first approved for very severe cases, but has just been approved for less advanced cancers.

“It’s the most promising drug for 15 years,” says Jamil Asselah, an oncologist at the McGill University Health Center (MUHC) who participated in clinical trials of Enhertu (trastuzumab deruxtecan). “And there’s a whole new class of similar drugs that’s on the way. »

Additionally, Enhertu could be used against other types of cancer. The D^r Asselah was on Friday at a congress of gastroenterological oncology in San Francisco. “Everybody talks about Enhertu at the congress,” he says.

Enhertu is an “antibody conjugate” that combines an antibody targeting the HER2 protein, expressed in half of breast cancer tumours, with a chemotherapy agent toxic to the tumour.

“In this way, the toxicity for other cells is reduced to a minimum”, explains Dr.^r Asselah. Breast cancer has a good prognosis compared to other cancers, but many patients are very sick and die of it.

Extended Approval

Enhertu’s first approval in Canada was in 2021 for women whose breast cancer had very high expression of HER2 and was at a very advanced stage. The length of time without the cancer coming back jumped, doubling to 10 months in some studies.

The new Canadian approval of Enhertu, at the beginning of January, concerns cases with low expression of the protein in question. “About 20% of patients have highly expressed HER2,” says Dr.^r Asselah. If we add the patients with a low expression of HER2, we arrive at almost 50% of the patients. »

About a hundred Quebec women took part in clinical trials of Enhertu. “Right now in Quebec, it is not possible to have it for cancers with low HER2, but we can give it to patients if we include them in clinical trials, says Dr.^r Asselah. This week, I included four women in this way. They knew the drug, the patients get a lot of information on social networks. »

long-term medication

The goal with Enhertu and the other antibody conjugates about to hit the market is to turn breast cancer into a chronic disease.

The only problem is that cancers develop resistance to certain chemotherapy molecules. “We see signs of resistance with Enhertu, says the D^r Asselah. But we’re going to have a lot of conjugated antibodies, so we’re not helpless. “Therapies combining several conjugated antibodies could see the light of day, such as triple therapy for AIDS.

The HER2 protein was also the target of Herceptin (trastuzumab), a drug that was a precursor to conjugated antibodies. “Herceptin only worked with cases of high HER2 expression and was not very specific,” says Dr.^r Asselah.