Honolulu scientists at the University of Hawaiʻi Cancer Center say a small change to a big-ticket cancer drug could make a major difference for patients whose tumors have stopped responding. Their move: when a breast tumor becomes resistant to an antibody-drug conjugate, or ADC, swap out the toxic payload attached to the antibody instead of abandoning ADCs altogether.
In lab dishes and mouse models, that simple switch restored tumor control in cancers that had already learned how to shrug off two widely used ADCs. The work, unveiled this week at a major breast cancer meeting, suggests oncologists might soon have a straightforward rule of thumb for picking the next ADC after a patient’s disease progresses.
What the lab work showed
The UH team engineered breast cancer models that had become resistant to two commonly used ADCs and saw that resistance spill over when both drugs carried the same active ingredient. When the researchers changed the payload from a DNA-targeting topoisomerase-I inhibitor to a drug that blocks cell division, tumor control came back in both cell cultures and mice.
The findings were reported in a press release from University of Hawaiʻi at Mānoa and presented on December 10, at the San Antonio Breast Cancer Symposium.
Real-world data lines up with the lab
Clinical data have hinted at the same pattern. When patients receive a second ADC, it tends to work less well if it uses the same type of payload as the first. In a multi-center retrospective analysis reported in PubMed Central, patients whose second ADC carried a different class of drug enjoyed longer progression-free survival than those who stayed with a similar payload.
Put together with the UH lab work, that real-world signal suggests that at the bedside, sequencing ADCs by payload type - not just by which tumor marker they target - could matter a lot.
Why the payload can make or break an ADC
ADC drugs work like guided missiles: an antibody steers the treatment to a marker on cancer cells and then delivers a highly potent chemotherapy payload inside the tumor. Different payloads kill cells in different ways. Topoisomerase-I inhibitors damage DNA, while other payloads disrupt microtubules and stop cells from dividing.
Those distinct attack routes help explain why resistance to one ADC does not automatically doom a follow-up ADC that carries a different kind of drug. For a deeper dive into how ADCs are built and how resistance develops, see the review in Clinical Medicine Insights: Oncology.
Why this matters in Hawaiʻi
The findings come out of the UH Cancer Center, Hawaiʻi’s only National Cancer Institute-designated cancer center. Based in Kakaʻako, the center directly employs more than 300 faculty and staff and reports an economic impact of over $57 million statewide.
Just as important for patients, the center works with a network of local clinical partners, creating a pipeline to bring discoveries from the lab into clinical trials on Oʻahu and beyond. According to the UH Cancer Center, that setup could help more patients stay in Hawaiʻi for advanced treatment instead of flying to the mainland when they need next-line therapies.
What the researchers say
“A simple takeaway is this: After a cancer progresses on one ADC, choose the next ADC with a different kind of drug,” said Jangsoon (Jason) Lee, PhD.
Naoto T. Ueno, director of the UH Cancer Center, stressed that resistance does not have to be the final word. “Drug resistance is not necessarily the end of the line for cancer patients,” he said, framing the team’s larger goal of matching the next ADC to the way each tumor escapes treatment. That message echoes the center’s press materials from University of Hawaiʻi at Mānoa.
What’s next for patients and trials
The investigators say they are now working with clinical partners and consortium members to design trials that pair an ADC’s payload with the specific resistance mechanisms in a patient’s tumor. The hope is to stretch out the benefit of treatment for people who have already burned through standard options.
If upcoming clinical studies confirm the preclinical signal, oncologists could gain a clear, evidence-based rule for sequencing ADCs instead of relying on educated guesswork. For Hawaiʻi patients, it could also mean more chances to access these next-line therapies close to home through the UH clinical network.
