Receptor tyrosine-protein kinase erbB-2 (48-56)

Background: The addition of trastuzumab (T) and lapatinib (L) to neoadjuvant chemotherapy increases the pathological complete response (pCR) rate in patients with human epidermal growth factor receptor 2 (HER2)-positive early breast cancer. We investigated the efficacy of T or L with neoadjuvant chemotherapy and specific efficacy biomarkers. Methods: Patients with stages I-III (including inflammatory) HER2-positive breast cancer were randomised to receive epirubicin (E) plus cyclophosphamide (C) × 4 cycles followed by docetaxel (D) plus either T (EC-DT) or L (EC-DL). End points included pCR (primary), clinical response, toxicity, and pCR-predictive biomarkers. Results: We randomised 102 patients to EC-DT (50) and EC-DL (52). Median age was 48, 56% were premenopausal and 58% had oestrogen receptor (ER)-positive tumours. Pathological complete response in breast was 52.1% (95% CI:38.0-66.2%) for EC-DT and 25.5% (95% CI:13.5-37.5%) for EC-DL (P=0.0065). Pathological complete response in breast and axilla was 47.9% for EC-DT and 23.5% for EC-DL (P=0.011). Grade 3-4 toxicity did not differ across treatments, except for diarrhoea (2% in EC-DT vs 13.5% in EC-DL, P=0.030). Multivariate analyses showed that treatment (P=0.036) and ER (P=0.014) were the only predictors of pCR in both groups. Conclusion: EC-DT exhibited higher efficacy and lower toxicity than EC-DL. Of the different biomarkers studied, only the absence of ER expression was associated with increased pCR.

DARPins fused with other proteins are promising non-immunoglobulin scaffolds for specific binding to target cells. In this study HER2-specific DARPin (DARPin_9-29) was used as a tumor-targeting moiety for the delivery of a cytotoxic agent - the fragment of Pseudomonas aeruginosa exotoxin A. It was determined that DARPin-PE40 possesses a considerable cytotoxic activity and induces apoptosis in HER2-positive cells. Cytotoxic effect of DARPin-PE40 strongly correlates with the HER2 expression level. The effect of intravenous administration of DARPin-PE40 was tested in the xenograft model of breast cancer. It was shown that treatment of animals with DARPin-PE40 caused strong and prolonged suppression of xenograft tumor growth.

Background: Liposomes have been employed to improve pharmacokinetics and reduce side effects of drugs. They can be functionalized with antibodies for targeted delivery. While the monoclonal antibody trastuzumab has been employed in the therapy of HER2-positive breast cancer, the resistance developed during treatment has been reported. Rapamycin could be used in combination with trastuzumab for improved therapeutic response. Objective: In this study, we aimed to develop rapamycin-loaded liposomes and immunoliposomes with trastuzumab, characterize them and evaluate their in vitro cytotoxicity. Method: Formulations were prepared by the thin film hydration method and immunoliposome was conjugated to antibody by covalent bond. Characterization involved particle size, polydispersity, zeta potential, encapsulation efficiency, functionalization efficiency, DSC and FTIR assays. Cell studies were conducted through the MTT assay. Results: SPC:Chol:DSPE-PEG formulation prepared at 1:10 drug to lipid ratio presented high encapsulation efficiency, appropriate particle size, low polydispersity, negative zeta potential and colloidal stability. Rapamycin exhibited intermolecular interactions with lipids and underwent crystallinity reduction. Rapamycin-loaded immunoliposomes were prepared with high trastuzumab functionalization efficiency and antibody stability. Cytotoxicity studies showed that the HER2-positive SK-BR-3 cell line was sensitive to trastuzumab, either as free drug or in the context of immunoliposomes, and is more sensitive to rapamycin than the triple negative MDA-MB-231 cells. For MDA-MB-231, the liposomal rapamycin was more cytotoxic than the free drug. Furthermore, the immunoliposomes showed potent cytotoxicity against SK-BR-3 cells. Finally, rapamycin and trastuzumab exhibited in vitro synergistic effect, particularly through immunoliposomes. Conclusion: The formulation developed herein has potential for in vivo evaluation.