A drug combination taken before surgery shrinks and may even destroy tumours in women with HER2 positive disease within 11 days, a UK trial has found.
The research, involving the drugs lapatinib and trastuzumab (Herceptin), may lead to fewer women needing chemotherapy, according to researchers.
“It was unexpected to see quite such dramatic responses to the trastuzumab and lapatinib within 11 days”
The results are from a Cancer Research UK-funded trial were presented at the European Breast Cancer Conference earlier today.
The EPHOS B trial studied 257 women with HER2 positive breast cancer in the short gap between initial diagnosis and surgery to remove their tumours.
Women were randomised to receive either trastuzamab, or lapatinib or no treatment for 11 days before their surgery. Halfway through the study, additional women allocated to the lapatinib group were also prescribed trastuzumab.
The trial set out to study the biological effects of the drug combination by measuring biological markers of cellular proliferation after 11 days of therapy.
Drug combo shrinks HER2 breast cancers ‘within 11 days’
But the researchers discovered that in around a quarter of the 66 women who received both drugs the remaining tumour was too small for the second measurement of cell proliferation.
They found 17% of the women receiving both drugs had only minimal residual disease – defined as an invasive tumour smaller than 5mm in size – and 11% had a pathological complete response, with no biological sign of invasive tumour found in the breast.
In comparison, 3% of the women treated with trastuzumab alone had only residual disease or complete response.
Complete response is common after three to four months with current treatments, but the researchers said observing a disease response after 11 days was “very surprising”.
Trial co-leader Professor Judith Bliss, from the Institute of Cancer Research in London, said: “It was unexpected to see quite such dramatic responses to the trastuzumab and lapatinib within 11 days.
“Our results are a strong foundation on which to build further trials of combination anti-HER2 therapies prior to surgery – which could reduce the number of women who require subsequent chemotherapy,” she added.
“This could mean some women can avoid chemotherapy after their surgery”
Trial co-leader Nigel Bundred, professor of surgical oncology at Manchester University and a consultant at University Hospital of South Manchester NHS Foundation Trust, said: “These early and significant tumour regressions… suggest that we will be able to personalise treatment for these cancers on the basis of early response.”
Professor Arnie Purushotham, senior clinical adviser at Cancer Research UK, added: “These results are very promising if they stand up in the long run and could be the starting step of finding a new way to treat HER2 positive breast cancers.
“This could mean some women can avoid chemotherapy after their surgery – sparing them the side-effects and giving them a better quality of life,” he said.