Response Prediction to Neoadjuvant Chemotherapy: Comparison between Pre-Therapeutic Gene Expression Profiles and In Vitro Chemosensitivity Assay

Abstract

Although the use of (neo-)adjuvant chemotherapy in breast cancer patients has resulted in improved outcome, not all patients benefit equally. We have evaluated the utility of an in vitro chemosensitivity assay in predicting response to neoadjuvant chemotherapy. Pre-therapeutic biopsies were obtained from 30 breast cancer patients assigned to neoadjuvant epirubicin 75 mg/m2 and docetaxel 75 mg/m2 (Epi/Doc) in a prospectively randomized clinical trial. Biopsies were subjected to a standardized ATP-based Epi/Doc chemosensitivity assay, and to gene expression profiling. Patients then received 3 cycles of chemotherapy, and response was evaluated by changes in tumor diameter and Ki67 expression. The efficacy of Epi/Doc in vitro was correlated with differential changes in tumor cell proliferation in response to Epi/Doc in vivo (p = 0.0011; r = 0.73670, Spearmańs rho), but did not predict for changes in tumor size. While a pre-therapeutic gene expression signature identified tumors with a clinical response to Epi/Doc, no such signature could be found for tumors that responded to Epi/Doc in vitro, or tumors in which Epi/Doc exerted an antiproliferative effect in vivo. This is the first prospective clinical trial to demonstrate the utility of a standardized in vitro chemosensitivity assay in predicting the individual biological response to chemotherapy in breast cancer.

Direct Chemosensitivity Monitoring Ex Vivo on Undissociated Melanoma Tumor Tissue by Impedance Spectroscopy

“…Although established molecular biologic assays based on dissociated and recultivated tumor cells showed predictive benefits for single tumor entities (4,5), recent studies also demonstrated clear limitations of the predictive power for different tumor entities like the malignant melanoma (6). Moreover, actual studies revealed that 2D cultures show substantial alterations with regard to chemotherapeutic sensitivity when compared with 3D cultures (10)(11)(12)(13) and that the tumor cell microenvironment like extracellular matrix components and individual cell-cell contacts are important for tumor biology as well as responsiveness to chemotherapeutics (25,26).…”

“…Although previously developed chemosensitivity assays like the colony-forming unit assay, proliferation assay, and the MTT assay showed limited usefulness (2), the ATP assay (ATP-TCA) revealed promising results at least for the prediction of resistance for ovarian cancer (3) but limited for the prediction of sensitivity (4,5). For other tumor entities like mamma carcinoma and melanoma, the ATP-TCA assay also revealed limited prediction capabilities (6,7). Especially for melanoma studies, it was revealed to be inapplicable for certain drugs like dacarbazine or temozolomide (8).…”

“…The major drawback of all the established chemosensitivity assays is the need of an extended amount of tissue (> 1 cm 3 ) for quantitative analysis of at least 4 to 6 compounds (9). Moreover, the tumor tissue has to be completely dissociated, followed by further selection, filtering, and recultivation steps, resulting in a complete loss of the original tissue organization, the extracellular matrix, and probably of whole cell populations (6). Especially in the context of tissue organization, recent studies demonstrated that the chemotherapeutic response pattern can be substantially altered in two-dimensional (2D) cultures (10)(11)(12)(13).…”

Personalized in vitro cancer models to predict therapeutic response: Challenges and a framework for improvement

“…One study reported increased overall survival in the ATP assay directed group (Ugurel et al, 2006) while another group reported that survival was not improved (Cree, Kurbacher, Lamont, Hindley, & Love, 2007). The MTT assay was also used to evaluate epirubicin and docetaxel sensitivity in primary human breast cancer cells and correctly predicted changes in cancer cell proliferation but not overall tumor size (Singer et al, 2013). The MTT assay was used to predict drug effectiveness in 353 gastric cancer patients but no difference in clinical outcome was found between the control group and the MTT sensitive group (Wu, et al, 2008).…”

Changes in Expression of Genes Representing Key Biologic Processes after Neoadjuvant Chemotherapy in Breast Cancer, and Prognostic Implications in Residual Disease

“…The genes were chosen from literature review on the basis of their being identified as (i) possible prognostic factors in residual disease at protein (4,(6)(7)(8)(9)(10) or mRNA level (11), (ii) as significantly up-or downregulated, but of unknown prognostic value in residual disease (12)(13)(14)(15)(16)(17)(18)(19)(20), (iii) as predictive of chemotherapy resistance (6,11,16,19,(21)(22)(23)(24)(25)(26)(27)(28)(29), and/or (iv) identified as possible prognostic factors over several previous datasets (26,(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41). In addition to the previously established prognostic factors ESR1 and ERBB2, the genes were also chosen to represent different pathways and biological processes of known implication in tumor progression or response to therapy, such as stemcellness (ALDH1A1, CD44, and STAT3), proliferation (TOP2A, MKI67, and AURKA), apoptosis (BCL2, BCL2L1, and PAWR), immunologic response (CD3D, CXCL13, and STAT1), epithelial-to-mesenchymal transition (EMT; SNAI1, SNAI2, SOX9, and TWIST), stromal activation (DECORIN, ...…”