Women with HER2 positive breast cancer could see their tumours shrink or disappear altogether if they take a combination of drugs, a conference heard yesterday.
The “ground-breaking” discovery comes after a study found that a quarter of women with the variant saw their tumours shrink significantly or disappear after 11 days when they were treated with a combination of lapatinib and trastuzumab before surgery and chemotherapy.
Speaking at the 10th European Breast Cancer Conference (EBCC-10), in Amsterdam, The Netherlands, yesterday (10 March, 2016), Professor Nigel Bundred told delegates that the offered new scope for personalised treatment.
“This has ground-breaking potential because it allows us to identify a group of patients who, within 11 days, have had their tumours disappear with anti-HER2 therapy alone and who potentially may not require subsequent chemotherapy,” he said, presenting the results from the UK EPHOS-B multi-centre clinical trial.
“This offers the opportunity to tailor treatment for each individual woman.”
Prof Bundred, professor of Surgical Oncology at The University of Manchester and the University Hospital of South Manchester NHS Foundation Trust (UK), said the study focused on 257 women who had newly-diagnosed, operable, HER2 positive disease between November 2010 and September 2015. Some had stage 2 breast cancer.
In the first part of the study, 130 participants were randomly selected to receive no pre-operative treatment (the control group), or trastuzumab (Herceptin) only, or lapatinib (Tyverb) only, for 11 days after diagnosis and before surgery.
As evidence emerged from other trials as to the success of the combination of lapatinib and trastuzumab to treat HER2 positive breast cancer, the second part of the trial was amended so that, from August 2013, the next 127 women were randomised to the control group, or to receive trastuzumab only, or the combination treatment. For both parts of the trial, the women continued to receive standard of care treatment after surgery.
Samples of tumour tissue were taken from the first biopsy and were analysed to see if there had been a drop in levels of the Ki67 protein, an indicator of cell proliferation, or a rise in apoptosis (programmed cell death) of 30% or more from the time of the first biopsy.
Researchers also examined pathology reports on the tissue taken during surgery, and the women were then categorised as either having pathological complete response (pCR) if no active cancer cells had been found, minimal residual disease (MRD) if the tumour was less than 5mm in diameter, or other.
Results from the second part of the trial, analysed in February 2016, showed that, in addition to observing a drop in Ki67 for women who received the combination treatment, 11% had pCR and 17% had MRD.
For those women randomised to receive only trastuzumab, 0% had pCR and 3% had MRD and no patients had either pCR or MRD in the control group.
Professor Judith Bliss, lead researcher from The Institute of Cancer Research, London, which co-led the trial, said: “These results show that we can get an early indication of pathological response within 11 days, in the absence of chemotherapy, in these patients on combination treatment. Most previous trials have only looked at the pathological response after several months of treatment.
“Clearly these results need further confirmation, but I suspect the excitement from seeing the speed of disappearance of the tumours will mean that several trials will attempt to confirm these results.”
Abstract no: 6 LBA. “Effects of perioperative lapatinib and trastuzumab, alone and in combination, in early HER2+ breast cancer – the UK EPHOS-B trial (CRUK/08/002)”.
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