Reviewing LORELEI, mindACT and ExteNET trials in breast cancer

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Published: 9 Sep 2017
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Prof Miguel Martin - Hospital General Universitario Gregorio Marañón, Madrid, Spain

Prof Martin talks with ecancer at the ESMO 2017 Congress and reviews a breast cancer session that examined three trials:

- The ExteNET trail, looking at the use of neratinib for the extended adjuvant treatment of early stage HER2-positive breast cancer following trastuzumab-based therapy. 

- The MINDACT study, confirming the value of genomic profiling for patients with early breast cancer with zero to three positive lymph nodes. 

- The LORELEI trial, stating that adding taselisib to letrozole before surgery significantly improved outcomes for patients with early breast cancer that was both oestrogen receptor positive and HER2-negative.

There were three or four interesting presentations yesterday in breast cancer. One of them was about the PI3K inhibitor taselisib that combined with hormonal therapy, letrozole, reduced the size of tumours when used as neoadjuvant therapy in luminal cancer. So it’s very interesting because this is the first time this is proven in a clinical setting and this opens a window of opportunity for the drug to be introduced in other settings, in the metastatic setting, in the adjuvant setting and so on. The toxicity of the drug is quite manageable. So this is the first presentation I would like to remark.

The second one is the five year update of the ExteNET trial. The ExteNET trial is an adjuvant trial using neratinib as adjuvant extended therapy after trastuzumab and chemotherapy in operable HER2 positive breast cancer. Neratinib significantly improved invasive disease free survival at five years versus placebo and this is a new drug available for treating HER2 positive breast cancer patients with early disease. This is very good news for medical oncology and for the patients; the drug has been approved for that in the USA and probably will be approved in Europe as well soon.

We had another presentation in which a subset analysis of the MINDACT trial showed that even very small tumours, breast cancer tumours, could be very dangerous if they are genomically bad. So studying small tumours is crucial to decide which ones need chemotherapy because if we rely only on the tumour size we can have surprises later on in terms of relapses.

Out of all of these, do you think that the changes to clinicians in practice who are looking at treatment choices now, looking at patients’ tumour sizes now, is that going to be changing the way that we treat?

I think so. I think that vision of small tumours should change and we should be very careful with these small tumours and make sure that they are not bad tumours in terms of genomic profile. So this is an argument in favour of using the genomic platforms currently available for these small tumours in order to select those of a prognosis for chemotherapy.

Then the neratinib data looking for luminal tumours as well.

Yes, the neratinib study provided evidence that a new drug, effective drug, is available for HER2 positive disease. This is a new option for a subset of patients with HER2 positive operable breast cancer in addition to trastuzumab and chemotherapy and I am sure that it will be approved by the European authorities and it will be used in a subset of patients.