Ki67 as a predictive biomarker for pathologic complete remission in patients with eraly triple negative breast cancer (TNBC) receiving carboplatin-containing neoadjuvant chemotherapy (NACT)
Alhaik A.1, Kolberg-Liedtke C.2, Krajewska M.2, Hoffmann O.3, Pott B.4, Petzel A.2, Bankfalvi A.3, Shaheen M.1, Stephanou M.1, Kolberg H.-C.1
1Marienhospital Bottrop, Bottrop, Deutschland, 2Charité - Universitätsmedizin Berlin, Berlin, Deutschland, 3Universitätsklinikum Essen, Essen, Deutschland, 4Onkologische Gemeinschaftspraxis Bottrop, Bottrop, Deutschland

Introduction: Ki67 is established as a prognostic and predictive biomarker in early breast cancer. Although the prognostic and especially the predictive value is most relevant in hormone receptor positive HER2 negative patients, they have also been demonstrated in TNBC and HER2 positive cases. However, there are limited data regarding Ki67 as a predictor of pCR in triple negative patients treated with carboplatin-containing NACT.
Methods: We identified patients in our database who received neoadjuvant therapy for TNBC after incorporation of carboplatin as a standard in NACT for triple negative disease in the German AGO-recommendations. Patients who received no carboplatin and patients treated in clinical studies were excluded, leaving only those patients who had received carboplatin-containing NACT. The association between Ki67 and pCR (defined as ypT0 and ypN0) was calculated by univariate logistic regression.
Results: 22 patients were included with regard to the criteria mentioned above. 9 of those 22 (40.9%) patients achieved a pCR. Of all the parameters analyzed (age, tumor size, nodal status, grade, and Ki67) only age (mean 69 yrs (SD 13 yrs) vs. 51 yrs (SD 11 yrs), p=0.017) and Ki67 (30% [20%, 60%] vs. 80% [ 70%, 90%], p=0.033) were significantly associated with pCR.
Conclusion: Our analysis demonstrates that Ki67 is a predictive biomarker regarding pCR after carboplatin-containing NACT in TNBC. Due to the small sample size in our study we were not able to define a cut-off. However, among several other established biomarkers Ki 67 was one of two parameters showing a significant association with pCR.