Phase II Trial to Validate Markers for a Response Evaluation of a Combined Therapy in Patients With HER2+ Breast Cancer

Trastuzumab (T)-containing neoadjuvant chemotherapy has been reported to increase the probability of pathological complete response (pCR) in HER2 positive disease up to 67 %. Large trials revealed pCR rates (no remaining invasive and in situ components) of about 30-40 %, if anthracyclines/taxane based polychemotherapy was applied or about 40-45 % if no invasive tumor in the breast and lymph nodes was used as a pCR definition. Nevertheless, resistance to trastuzumab remains one of the most important challenges in adjuvant and metastatic breast cancer therapy causing poor prognosis with an increased incidence of cerebral metastasis and limited therapeutic options after disease progression6. An improvement shows the combination of trastuzumab and lapatinib, which has been reported to have increased efficacy in in-vitro and in metastatic setting in patients who were mostly resistant to both therapies in the previous course of disease. Recent data from the neoadjuvant setting (neoALTTO) - on a paclitaxel backbone - showed a significantly higher pCR rate after L + T than with either compound separately (47 % vs. 20 % and 27.6 % respectively). Several trials are planned to evaluate the combination of both therapies in the adjuvant and neoadjuvant setting. Clinical response measured by sequential evaluation of different proliferation markers (such as Ki-67) following a course of neoadjuvant chemotherapy has been demonstrated to correlate significantly with an increased risk of relapse in patients not achieving pathological complete response. It is therefore clinically relevant to evaluate such proliferation tools for early prediction of combination therapy efficacy (chemotherapy and HER2 targeted therapy). So far, it remains unclear which method of proliferation measurement is the optimal marker for response evaluation regarding a combined chemo-immunotherapy. However, measurement of proliferation and apoptosis genes as well as assessment of changes in Phosphatidylinositol 3-kinases (PI3K), Protein Kinase B (AKT), Insulin-like Growth Factor (IGF) and stem cell signalling after a short course of therapy could provide a unique signature for a dynamic response evaluation. The planned trial will validate predictive markers and a dynamic model based on the sequential evaluation of different proliferation and apoptosis markers. Furthermore it will assess the pCR-rate after 12 weeks of therapy. The aim of the study is to define a predictive marker for the response evaluation of a combined chemo-immunotherapy.