In logistic regression analysis, obesity (OR: 0.52, 95% CI: 0.28–0.97; p = 0.04) and a low Ki-67 score (HR: 2.7, 95% CI: 1.37–5.53; p = 0.003) were independently associated with a decreased rate of pCR. This evidence concerns the gene MKI67 and obesity due to melanocortin 4 receptor deficiency.