ATP-tumor Chemosensitivity Assay Research Articles

AURKA inhibition shows promise as a therapeutic strategy for ARID1A-mutant colorectal cancer

PurposeMutations in ARID1A frequently occur in colorectal cancer (CRC) cells. However, there are currently no clinical treatment options specifically addressing this aberration. The preliminary in vitro experiments revealed a synthetic lethal interaction between ARID1A and Aurora kinase A (AURKA) in colorectal cancer (CRC) cells.MethodsWe collected samples from 80 CRC patients and evaluated the efficacy of AURKA inhibitor (AURKAi) using the ATP-tumor chemosensitivity assay (ATP-TCA) on untreated ARID1A-proficient (ARID1A +) and ARID1A-deficient (ARID1A-) CRC patient samples. In addition, we validated this result by a clonogenic assay. Additionally, we examined the effects of AURKA inhibitors on cell cycle progression and apoptosis in ARID1A + and ARID1A- CRC patient samples using flow cytometry.ResultsThe results showed that AURKAi selectively inhibited the growth of ARID1A- CRC cells. Furthermore, AURKA inhibitors significantly increased G2/M arrest and induced apoptosis in ARID1A- cells.ConclusionWe believe that AURKAi hold promise as potential therapeutics for ARID1A mutation colorectal cancer patients.

Selective vulnerability of ARID1A deficient colon cancer cells to combined radiation and ATR-inhibitor therapy.

ARID1A is frequently mutated in colorectal cancer (CRC) cells. Loss of ARID1A function compromises DNA damage repair and increases the reliance of tumor cells on ATR-dependent DNA repair pathways. Here, we investigated the effect of ionizing radiation (IR), in combination with ATR inhibitors (ATRi) in CRC cell lines with proficient and deficient ARID1A. The concept of selective vulnerability of ARID1A deficient CRC cells to ATRi was further tested in an ex vivo system by using the ATP-tumor chemosensitivity assay (ATP-TCA) in cells from untreated CRC patients, with and without ARID1A expression. We found selective sensitization upon ATRi treatment as well as after combined treatment with IR (P<0.001), especially in ARID1A deficient CRC cells (P <0.01). Knock-down of ARID1B further increased the selective radiosensitivity effect of ATRi in ARID1A negative cells (P<0.01). Mechanistically, ATRi abrogates the G2 checkpoint (P<0.01) and homologous recombination repair (P<0.01) in ARID1A deficient cells. Most importantly, ex-vivo experiments showed that ATRi had the highest radiosensitizing effect in ARID1A negative cells from CRC patients. Collectively, our results generate pre-clinical and clinical mechanistic rationale for assessing ARID1A defects as a biomarker for ATR inhibitor response as a single agent, or in a synthetic lethal approach in combination with IR.

Evidence for heterogeneity in response to treatment in mammary tumors of dogs as happens in humans.

Tumors are formed by various clones developed over a long time. This gives rise to a heterogeneous nature. This heterogeneity is the hardest challenge in the treatment of cancers because it is the main reason for drug resistance. This is a well-known fact in human cancer. Therefore, we have reasoned that if the tumor heterogeneity in canine mammary gland tumors (CMGTs) could be shown by an ex vivo assay, which will be used first time in veterinary oncology practice, this could be used further in clinics. To achieve this, twenty-six patients were included in the study. Tumor tissues were obtained from animals during routine surgery. Tumor cells were isolated and seeded ex vivo. The cells were exposed to anticancer drugs that are clinically used. Seven days after the treatment, chemosensitivity has luminometrically been assayed by ATP-tumor chemosensitivity assay (ATP-TCA). It has clearly been shown that all the tumor tissues have responded to treatment differently, implying that heterogeneity exists in mammary tumors. There has also been found that there was a weak to moderate statistically significant correlation between tumor size and drug index. However, there has been no correlation between drug index and metastasis to lymph nodes. Hyperplasic areas had relatively higher PCNA values. The results of our study demonstrate the heterogeneity in responses to in vitro drugs. Clinical trials based on test results and follow-up studies with large numbers of animals are needed to prove that such chemotherapeutic activity assessment tests can be clinically useful in predicting drug responses in CMGTs.

A retrospective study of the correlation of in vitro chemosensitivity using ATP-TCA with patient clinical outcomes in acute myeloid leukemia.

To evaluate the predictive value of the in vitro chemosensitivity using ATP-TCA method to compare the clinical efficacy of patients with AML. Bone marrow or peripheral blood samples were collected from 65 patients with AML, and the in vitro chemosensitivity of four drugs (cytarabine/idarubicin/decitabine/aclacinomycin) was measured by an ATP-tumor chemosensitivity assay. Aclacinomycin and cytarabine had the highest chemosensitivity rates (66.7%, 8/12 and 58.5%, 38/65, respectively), while idarubicin and decitabine had rates of 6.5% (3/46) and 0% (0/35), respectively. Complete remission (CR) was achieved in 66.2% (43/65) of patients, and there was a statistically significant correlation between CR and in vitro chemosensitivity for cytarabine (47.7% vs 18.5%, p = 0.002), but not for the anthracyclines (p = 0.950). In addition, three other factors significantly correlated with CR: disease status (p = 0.005), FLT3-ITD/TKD mutation (p = 0.003) and chemotherapy regimens (p = 0.004). Furthermore, multiple logistic regression analysis revealed that the sensitivity of cytarabine was one of the significant risk factors for CR [hazard ratio (HR) = 5.52; 95% confidence interval (CI) = 1.47-20.70; p = 0.011]. The in vitro chemosensitivity as tested by ATP-TCA demonstrated a significant correlation with CR for chemotherapy and can be a useful tool to optimize personalized treatments for patients with AML.

ATP-tumor chemosensitivity assay directed chemotherapy in patients with cervical cancer

To select suitable chemotherapy for cervical cancer patients by ATP-tumor chemosensitivity assay. Seventy-two hospitalized patients with cervical cancer between July 2007 and October 2009 were enrolled. The patients were randomly divided into a trial group (n=35) and a control group (n=37). ATP-TCA was used to detect the sensitivity of 35 samples of cervical cancer in the trial group to 6 combined chemotherapy regimens. The chemotherapy regimen in the trial group was confirmed by the results of susceptibility testing and that in the control group was confirmed by clinical experience. One-year recurrence rate and 3- year survival rate of two groups were compared after 3 year follow-up. ATP-TCA was measured in 32 of the 35 patients in the trial group. The sensitive patients for paclitaxel+carboplatin, paclitaxel+oxaliplatin, bleomycin+ifosfamide+cisplatin, bleomycin+vincristine+cisplatin, fluorouracil+cisplatin, and gemcitabine+cisplatin were 20, 18, 17, 18, 17, and 21, respectively. There was no significant difference in the 1-year recurrence between the two groups (P>0.05), while the 3-year survivors in the trial group were more than those in the control group (P<0.05). ATP-TCA method is good for patients with cervical cancer because it is sensitive, effective, and individualized.

GRP78 expression in gastric cancer and its clinical significance

To investigate the clinical value of the expression of glucose regulated protein 78 (GRP78) for assessment of severity, chemoresistance and prognosis in patients with gastric adenocarcinoma ( GC) . A cohort of 237 patients with gastric cancer was included in this study. 160 patients of them were treated by D2 radical gastrectomy and adjuvant chemotherapy. The GRP78 expression was detected by immunohistochemistry and 80 patients of them were tested in vitro for cancer chemosensitivity by ATP-tumor chemosensitivity assay (ATP-TCA). In addition, the relationships were analyzed between GRP78 and age, gender, tumor differentiation, invasion, disease stage, lymph node metastasis and chemoresistance as well as disease-free survival (DFS). The positive rate of GRP78 expression in the gastric adenocarcinoma was 68.8% before the initiation of chemotherapy. The positive GRP78 expression was significantly correlated with tumor invasion depth, poor differentiation, TNM stages, and lymph node metastasis (all P < 0.05), not correlated with gender and age, and high GRP78 expression was associated with the chemoresistance of the gastric cancer cells to chemotherapeutic agents. Negative GRP78 expression was associated with higher sensitivity to both drugs and regimens. The DFS of GRP78-positive group and GRP78-negative group was (53.6 ± 0.9) months and (38.3 ± 0.8) months, respectively (P = 0.041). Interestingly, subgroup analysis revealed that the DFS in GRP78-negative and-positive patients treated with taxane-containing chemotherapy was (58.6 ± 2.6) months and (49.1 ± 2.7) months, respectively, but the difference was statistically not significant (P = 0.111). In contrast, in the subset of GRP78-negative and- positive patients treated with taxane-containing regimens, the DFS was (45.5 ± 1.9) months and (35.1 ± 2.2) months, respectively, showing a significant difference (P = 0.038). In the group of patients with positive GRP78 expression, the patients treated with taxane-containing chemotherapy had a longer DFS [(49.1 ± 2.7) months] than those without that treatment [(35.1 ± 2.2) months], showing a significant difference (P = 0.017). Univariate analysis revealed that DFS was correlated with histological grade, GRP78 expression and lymph node metastasis (all P < 0.05). Multivariate analysis showed that GRP78 expression and TNM staging were independent influencing factors for gastric cancer (both P < 0.05). The results of our study suggest that GRP78 may be a novel biomarker for assessment of malignant degree and prediction of chemoresistance in gastric cancer, and may be helpful to chemotherapy planning and prognosis prediction in patients with gastric cancer.

Enhanced RegIV Expression Predicts the Intrinsic 5-Fluorouracil (5-FU) Resistance in Advanced Gastric Cancer

RegIV, a member of the Regenerating (REG) gene family, may be a marker for the prediction of resistance to 5-fluorouracil (5-FU)-based chemotherapy. However, the relationship between the intrinsic drug resistance of gastric cancer (GC) cells to 5-FU used alone (single FU) or in multidrug therapeutic regimens (5-FU combinations) and RegIV expression has not been investigated. The patient cohort comprised 45 patients with primary GC. The chemoresistance of GC cells to therapeutic regimens consisting of single 5-FU or FU combinations was investigated using the ATP-tumor chemosensitivity assay. The level of RegIV mRNA transcripts was determined by real-time reverse transcriptase-PCR. RegIV expression was evaluated as a novel predictive biomarker for the intrinsic drug resistance of primary GC cells to single 5-FU or 5-FU combinations. Upregulation of RegIV mRNA transcripts was observed in 36 of the 45 tumor specimens and was positively correlated with the invasive depth of the tumor cells (p = 0.000), the clinical stages (p = 0.000) and the in vitro intrinsic drug resistance of primary GC cells to 5-FU (p = 0.000) or 5-FU combinations. RegIV mRNA transcript level was strongly associated with the intrinsic resistance of GC cells to single 5-FU or 5-FU combinations, suggesting that RegIV may play an important role in the intrinsic resistance of GC cells to 5-FU and that targeted therapy against the RegIV gene could be applied to overcome 5-FU resistance in the treatment of GC.

Antitumor activity of zoledronic acid in primary breast cancer cells determined by the ATP tumor chemosensitivity assay.

BackgroundThe NeoAzure study has demonstrated that the use of the bisphosphonate zoledronic acid (Zol) in the neoadjuvant setting increases the rate of complete response in primary breast cancer and therefore indicates direct antitumor activity. The purpose of this study was to compare the antitumor effect of Zol with standard chemotherapy in primary breast cancer cells using ATP-tumor chemosensitivity assay (ATP-TCA).MethodsBreast cancer specimens were obtained from patients with breast cancer who underwent primary breast cancer surgery at the Department of Obstetrics and Gynecology, Tübingen, Germany, between 2006 through 2009. Antitumor effects of Zol, TAC (Docetaxel, Adriamycin, Cyclophosphamide) and FEC (5-Fluorouracil, Epirubicin, Cyclophosphamide) were tested in 116 fresh human primary breast cancer specimens using ATP-TCA. ATP-TCA results were analyzed with different cut-off levels for the half maximal inhibitory concentration (IC50), for IC90 and for the sensitivity index (IndexSUM). Each single agent or combination was tested at six doubling dilutions from 6.25, 12.5, 25, 50, 100, and 200% of test drug concentrations (TDC) derived from the plasma peak concentrations determined by pharmacokinetic data. The assay was carried out in duplicate wells with positive and negative controls.ResultsThe median IndexSUM value was lower for Zol than for the combined regimen FEC (36.8%) and TAC (12.9%), respectively, indicating increased antitumor activity of Zol in primary breast cancer cells. The difference regarding Zol and FEC was significant (p < 0.05). The median IC50 value for Zol (8.03% TDC) was significantly lower than the IC50 values for FEC (33.5% TDC) and TAC (19.3% TDC) treatment (p < 0.05). However, the median IC90 value for Zol (152.5% TDC) was significantly higher than the IC90 value obtained with TAC (49.5% TDC; p < 0.05), but similar to the IC90 value for FEC (180.9% TDC). In addition a significant positive correlation was observed for the IndexSum of Zol and the ER status (p < 0.01).ConclusionZoledronic acid has a strong antitumor effect on primary breast cancer cells in vitro which is equal or superior to commonly used chemotherapeutic regimens for treating breast cancer.

Heterogeneity of chemosensitivity in esophageal cancer using ATP-tumor chemosensitivity assay

Current chemotherapy for esophageal cancer is conducted on the basis of empirical information from clinical trials, which fails to take into account the known heterogeneity of chemosensitivity between patients. This study was aimed to demonstrate the degree of heterogeneity of chemosensitivity in esophageal cancers. A total of 42 esophageal cancer specimens were collected. The heterogeneity of chemosensitivity in esophageal cancer specimens was examined using an ex vivo ATP-tumor chemosensitivity assay (ATP-TCA). Thirty eight specimens produced evaluable results (90.5%). The most active single agent tested was nedaplatin, to which 28.9% of samples were sensitive. Combinations of chemotherapy agents exhibited much higher sensitivity: cisplatin + paclitaxel was sensitive in 16 of 38 (42.1%) of samples, while nedaplatin+paclitaxel was more effective, which was sensitive in 20 of 38 cases (52.6%). There was a marked heterogeneity of chemosensitivity in esophageal cancer. Chemosensitivity testing may provide a practical method for testing new regimens before clinical trials in esophageal cancer patients.

Antitumor activity of zoledronic acid in primary breast cancer cells determined by the ATP tumor chemosensitivity assay

The NeoAzure study has demonstrated that the use of the bisphosphonate zole-dronate in the neoadjuvant setting increases the rate of complete response in primary breast cancer and therefore indicates direct antitumor activity (Coleman et al. 2010). The purpose of this study was to compare the antitumor effect of zolendronic acid with standard chemotherapy in primary breast cancer cells using ATP-tumor chemosensitivity assay (ATP-TCA).

Cytotoxicity of the new antimetabolite-bisphosphonate (5-FdU-alendronate) in comparison to standard therapeutics on breast and ovarian cancer cell lines in the ATP tumor chemosensitivity assay

Bisphosphonates (BPs) are bone specific palliative therapeutics that reduce tumorand cancer treatment-induced skeletal complication [1–3]. Further, they are an effective treatment for preventing skeletal-related events in patients with bone metastasis and may preserve functional independence as well as quality of life. Besides their action on osteoclasts short-term treatment with zoledronic acid has a clear anti-tumour effect on breast cancer cells which is supposed to be mediated by inhibiting the mevalonate pathway [4, 5]. All BPs share a common P-C-P “backbone” with two phosphonate (PO3) groups covalently linked to carbon. BPs are analogues of pyrophosphates where the PO-P linkage is replaced by P-C-P. The central carbon atom is generally linked to two geminate phosphates, a tertiary hydroxyl group and a variable side chain. The chemical properties, the mode of action and the therapeutic efficacy are more or less determined by the variable side chain. The tertiary hydroxyl group supports the bone-binding of the geminate phosphate groups. As bone is the most common site for metastasis from solid tumors and the majority of patients suffering of those malignancies develop bone metastasis at some point of their disease, there is a high demand for the development of more effective therapeutics against tumor-induced bone disease. In search of new treatment options, chemical modification approaches with BPs have been chosen as potential methods in order to enhance and prolong pharmacological effects in bone along with reducing adverse effect in other tissues [6]. Cytostatica like methotrexate [7], doxorubicin [8] or cisplatin [9] have been covalently attached via a chemical linkage to the terminal amino group of amino-BPs. The obtained conjugates should survive in the circulation, bind to the mineral matrix of the bone and subsequently release both, BPs as well as the linked cytostatica, by cleavage of the conjugates in the bone microenvironment. However, the cytostatic activities of these conjugates were evaluated in certain in vitro cell assays as well as in animal models and proved to be modest. Thus, it is to claim that the amide binding between the BPs and the cytostatica was perhaps not the postulated optimal linkage, being either too stable or too unstable in vivo to provide the desired concentration of cytostatic compounds in the bone [6]. In another approach the conjugation of BPs with the well-established antimetabolites 5-fluorodeoxyuridine (5FdU) and ara-cytidine (araC) was performed by condensation of the low cytostatic active etidronate or medronate with the 5′-monophosphates of 5-FdU or araC (see Fig. 1). The obtained nucleoside-5′-triphosphate analogs S. Schott :M. Wallwiener Department of Gynaecology and Obstetrics, National Center for Tumour Diseases (NCT) , University of Heidelberg, 69115 Heidelberg, Germany

Antitumor activity of zoledronic acid in primary breast cancer cells determined by the ATP tumor chemosensitivity assay.

e11112 Background: The NeoAzure study has demonstrated that the use of the bisphosphonate zole-dronate in the neoadjuvant setting increases the rate of complete response in primary breast cancer and therefore indicates direct antitumor activity (Coleman et al. 2010). The purpose of this study was to compare the antitumor effect of zolendronic acid with standard chemotherapy in primary breast cancer cells using ATP-tumor chemosensitivity assay (ATP-TCA). Methods: Breast cancer tissues were obtained from patients with breast cancer who underwent primary breast cancer surgery at the Dept of OB/Gyn, Tubingen, Germany, between 2006 through 2009. Antitumor effects of zoledronic acid (Zol), TAC (docetaxel, doxorubucin hydrochloride, cyclophosphamide) and FEC (5-fluorouracil, epirubicin, cyclophosphamide) were tested in 116 fresh human primary breast cancer specimens using ATP-TCA. ATP-TCA results were analyzed with different cut-off levels for the half maximal inhibitory concentration (IC50) and for IC90 and for...

ATP chemosensitivity testing of new antitumor duplex drugs linking 3`-C-ethynylycytidine (ECyd) and 2´-deoxy-5-fluorouridine (5-FdU) in comparison to standard cytostatica and combinations thereof

2´-Deoxy-5-fluorouridylyl-(5´-5´)-3´-C-ethynylcytidine [5-FdU(5´-5´)ECyd] and 3´-C-ethynylcytidinylyl-(5´->1-O)-2-O-octadecyl-sn-glycerylyl-(3-Ο->5´)-2´-deoxy-5-fluorouridine [ECyd-lipid-5-FdU] are antitumor active duplex drugs and these heterodinucleoside phosphate analogues could be cleaved in vivo by wide-spread phosphodiesterases into different antitumor active antimetabolites. We cultured breast MCF-7, MDA-MB-231 and ovarian OVCAR-29 and OAW-42 cancer cell lines and used the luminometric measuring of the ATP tumor chemosensitivity assay to assess the in vitro activity of 5-FdU(5´-5´)ECyd and ECyd-lipid-5-FdU in comparison to standard single cytostatic agents and combinations thereof currently used in anticancer therapies. To allow comparison between samples and different regimens IndexSUM was determined based on the percentage tumor cell growth inhibition at each test drug concentration. Additionally, the cytostatic efficacy of 5-FdU(5´-5´)ECyd and ECyd-lipid-5-FdU was evaluated at a minimum of five concentrations at 10 fold dilutions using 60 human tumor cell lines including ovarian and breast cancer cell lines from the National Cancer Institute (USA). 5-FdU(5´-5´)ECyd and ECyd-lipid-5-FdU have a high cytostatic efficacy reaching 50% tumor cell growth inhibition at concentrations ranging between nano- and micomolar. IndexSum values for broad range efficacy in MCF-7 breast cancer cells were comparable to values obtained for standard drug combinations. Higher cytostatic efficacy was observed in MDA-MB-231 cells. The duplex drugs 5-FdU(5´-5´)ECyd and ECyd-lipid-5-FdU represent potential new chemotherapeutic drugs for breast and ovarian cancer cells which are comparable to currently used drug combinations and more potent in comparison to some monocytostatica used in cancer therapy.

In vitro chemosensitivity in breast cancer using ATP-tumor chemosensitivity assay

Chemotherapy for breast cancer is given on the basis of empirical information from clinical trials, an approach which falls to take into account the known heterogeneity of chemosensitivity between patients. This study aimed to demonstrate the degree of heterogeneity of chemosensitivity in breast cancers. In this study, we examined the heterogeneity of chemosensitivity in breast cancer specimens (n = 50) using an ex vivo ATP-tumor chemosensitivity assay (ATP-TCA). Assay evaluability was 92% in surgical biopsies or pleural aspirates. A variety of chemosensitivity agents were tested. We found that the most active single agent tested was paclitaxel, to which 65.9% of samples were sensitive. Combinations of agents also showed more strong sensitivity cases. The Adriamycin+5-FU demonstrated a strong sensitivity in 23 of 43 (52.3%) of samples. Adriamycin+paclitaxel was more effective, with strong sensitivity in 37 of 43 cases tested (86.0%). There was a marked heterogeneity of chemosensitivity in breast cancer. Chemosensitivity testing may provide a practical method of testing new regimens before clinical trials in breast cancer patients.

Predicting resistance to platinum-containing chemotherapy with the ATP tumorchemosensitivity assay in primary ovarian cancer

Predicting resistance to platinum-containing chemotherapy with the ATP tumorchemosensitivity assay in primary ovarian cancer

Application of ATP-TCA in clinic

ATP-tumor chemosensitivity assay(ATP-TCA)is a tumor chemosensitivity assay in vitro.Beacause of the special merites of A11P-TCA,it is seemed to be the most promising and effective method of tumor chemosensitivity in vitro.Application of ATP-TCA in clinic has got significant effects.ATP-TCA is a good method for individualized chemotherapy. Key words: Drug screening assay,antitumor; Drug therapy

Clinical outcomes of ATP-tumor chemosensitivity assay directed chemotherapy in hepatocellular carcinoma

This study aims to investigate the clinical response of ATP tumor chemosensitivity assay (ATP-TCA) directed chemotherapy regimens delivered via hepatic artery infusion in 104 cases of primary liver carcinoma (PLC). Tumor tissue was obtained via laparotomy and cultivated in vitro. This tissue was put through the assay to determine chemosensitivity. A single drug regimen of either 5-FU, MMC and ADM and a combination drug regimen were used. The treatment assigned was dependent on the result of the ATP-TCA. In the control group, 30 cases of diagnosed PLC were given the conventional three-combination drug. The two groups were evaluated after three courses of chemotherapy. The results are as follows. The overall response rate of sensitivity test ranged from 36% to 44% in the single drug therapy groups and 81% in the combination drug group. The clinical overall response rate was 75% in the treatment group and 56% in control group. The treatment group had better results than the control group as survival period over six months was 80% and over one year 44%. In the control group, survival period over six months was 60% and 30% over one year. In short, ATP-TCA directed chemotherapy shows better results for terminal stages of PLC in that you can decrease the dose of drugs thereby reducing the side-effects with possible improvements in therapeutic effects.

The effect of imatinib mesylate (Glivec) on human tumor-derived cells

Imatinib mesylate is a specific inhibitor of the Bcr-Abl protein tyrosine kinase that competes with ATP for its specific binding site in the kinase domain. It has activity against platelet-derived growth factor receptor alpha and beta (PDGFR-alpha and -beta), and c-kit, the receptor for stem cell factor. We have used a standardized ATP-tumor chemosensitivity assay and immunohistochemistry to determine the cytotoxicity of imatinib mesylate in tumor-derived cells from cutaneous and uveal melanoma, and ovarian carcinoma. Imatinib mesylate was tested at concentrations ranging from 2.0 to 0.0625 micromol/l alone and in combination with a cytotoxic drug (cisplatin, doxorubicin, paclitaxel or treosulfan). Imatinib mesylate showed low inhibition (IndexSUM>300) across the range of concentrations tested in this study, with few tumors exhibiting increasing inhibition with increased drug concentration. The median IC90 values for cutaneous and uveal melanoma and ovarian carcinoma were 13.2 micromol/l (4.0-294.3 micromol/l), 12.0 micromol/l (2.0-285.4 micromol/l) and 7.71 micromol/l (6.51-11.02 micromol/l), respectively. Imatinib mesylate potentiated the effect of different cytotoxics in 9% (5/54) of cases and had a negative effect in 13% (7/54) of cases, with no effect in the remainder. No correlation of effect was noted with c-kit, platelet-derived growth factor receptor-alpha or platelet-derived growth factor receptor-beta expression, assessed by immunohistochemistry. The signaling pathways mediated by activation of c-kit or platelet-derived growth factor receptor may act as antiapoptotic survival signals in some cancers and inhibition of these pathways may potentiate the activity of some cytotoxic drugs by inhibiting the survival signal. Growth inhibition, however, may reduce the efficacy of cytotoxic drugs, which tend to target proliferating cells preferentially, and clinical effects are therefore difficult to predict.

Cross-activity of various established antineoplastic regimens in primary breast cancer cells evaluated by the ex vivo ATP tumor chemosensitivity assay

20086 Recently, various chemotherapy (Ctx) regimens are established in operable breast cancer (BC). Whereas anthracylines are now standard in high-risk patients (pts), the future role of taxanes or classical CMF is still controversial. Moreover, little is known which Ctx will be individually beneficial. This particular information is unlikely to be obtained from randomized trials because simultaneous treatment of one single pt with different competing protocols is inappropriate. Thus, we used ex vivo sensitivity profiles from native primary BC assessed with the ATP tumor chemosensitivity assay (ATP-TCA) to analyze the cross-activity of different standard regimens in individual pts. Each Ctx was tested at six different levels over 1.5 log range including both therapeutical and supra-therapeutical concentrations. Resistance, complete, and incomplete sensitivity were determined using a semiquantitative score. The following head-to-head comparisons of ex vivo activity were made: CMF, 4-OOH-cyclophosphamide (4-HC)+methotrexate (MTX)+5-Fluorouracil (5-FU) vs. EC, epirubicin (EPI)+4-HC, n = 56; CMF vs. paclitaxel (PCT), n = 34; CMF vs. docetaxel (DCT), n = 49; EC vs. PCT, n = 51; EC vs. DCT, n = 35; EC vs. EPI+PCT (ET), n = 45; PCT vs. DCT, n = 34. The ex vivo response rates were in good agreement with the expected clinical activity: CMF 52%, EC 63%, ET 85%, PCT 52%, DCT 49%. CMF and EC were equally active (=) in 68% BCs, CMF was superior (&gt;) to EC in 16% and inferior (&lt;) in 16%. The corresponding proportions (=/&gt;/&lt;) for the other comparisons were: CMF vs. PCT, 45%/31%/24%; CMF vs. DCT, 40%/40%/20%; EC vs. PCT, 49%/31%/20%; EC vs. DCT, 40%/40%/20%; EC vs. ET, 53%/ 9%/38%; PCT vs. DCT 55%/21%/24%. Generally, ET was the most active regimen, being equal or superior to EC in the majority of cases. However, CMF is clearly not inferior to EC or single agent taxanes. PCT and DCT are apparently not always the same. Facing the broad heterogeneity of chemosensitivity demonstrated in this study, we were able to show that the results of randomized trials cannot always be translated to an individual pt. Cross-activity analyses using the ATP-TCA may thus prove useful to allow for a more rational design of clinical trials in primary BC. [Table: see text]

Microtubule-associated protein tau and in vitro paclitaxel sensitivity in primary breast cancer

20088 Background: Paclitaxel has an important role in the adjuvant therapy of primary breast cancer. Recently, microtubule-associated protein tau was described as a marker of paclitaxel sensitivity. We attempted to validate these findings in vitro utilizing the ATP tumorchemosensitivity assay (ATP-TCA). Methods: The in vitro drug sensitivity to paclitaxel was evaluated in 48 fresh primary breast cancer specimens using the ATP-TCA. ATP-TCA results were analysed using the area under the curve (AUC) of growth inhibition. These results were correlated with the expression of tau mRNA measured by quantitative RT-PCR (Spearman’s correlation coefficient). Tau was also compared between progesterone receptor (PgR) positive and negative and estrogen receptor (ER) positive and negative tumors, respectively (Wilcoxon test). Results: The correlation of tau with the AUC for paclitaxel was weak (r = −0.20) and disappeared when considering PgR positive and negative tumors separately (r = −0.004 and r = −0.048, respectively). Tau was found to be differentially expressed between PgR positive and negative as well as between ER positive and negative tumors (p &lt; 0.0005 in both tests). Conclusions: The expression of tau does not show independent predictive value for the in vitro paclitaxel sensitivity in primary breast cancer. No significant financial relationships to disclose.