Chemotherapy as we know it has saved millions of lives. From its beginnings in World War I and II to its ubiquity as a cancer treatment today, the medicine has redefined cancer care. But its side effects, including vomiting, hair loss and infections, can be brutal for patients.
In a few years though, cancer sufferers may not have to go through all that. Chemo’s status as the go-to therapy for many cancers may soon come to an end, supplanted by a new generation of smart drugs that hunt down malignant cells without damaging healthy ones.
Chemo works by killing cancer cells that are dividing rapidly. The problem is that also harms other cells that are dividing and growing including those that produce hair and skin. Antibody drug conjugates, or ADCs, promise to deliver the toxic drug directly to the cancer cell. They do this by deploying an antibody that’s designed to recognize a marker on the surface of a cancer cell.
Not only are the ADCs helping patients have fewer of the chemo-associated side effects, but they’re also more effective at killing the cancer cells.
Companies are pushing to ensure they can produce these drugs, with AstraZeneca recently announcing a new $1.5 billion ADC facility in Singapore.
Eliminating chemo and replacing it with something more effective like ADCs is “absolutely” an ambition, Susan Galbraith, AstraZeneca’s Executive Vice President of Oncology R&D, tells us. “There's good reason to expect that you can replace standard of care chemotherapy in many different settings across many different cancers,” says Galbraith.
But that's not going to happen tomorrow. She estimates that in the next five years ADCs will be approved as the first treatment in many cancers for patients for whom the disease has already spread.
Currently, ADCs tend to be reserved for later stage disease. But they are also showing signs that they can be effective earlier on. For example, Astra’s drug Enhertu slowed the progression of breast cancer more than chemotherapy for some women in a trial, the company said in April.
It's providing hope that they could move from bit part to starring role. “I could see a point in time where fewer and fewer cancers will be treated with chemotherapy and more and more patients will be treated with these smart, more targeted, more specific, more tailored types of drugs,” Sophia Karagiannis, professor of cancer immunology at King’s College London, says.
There's also work afoot to improve on the current crop of ADCs. The existing drugs are just the “tip of the iceberg” in terms of what can be accomplished, says Karagiannis. The next generation of these treatments could be even more intelligent — “smart warheads,” as she puts it, that could target specific vulnerabilities in cancer cells rather than just delivering general toxins.
“If you can target that then you’re really targeting the Achilles’ heel of cancer.” — Chloe Meley and Ashleigh Furlong