Heterogeneity of chemosensitivity of esophageal and gastric carcinoma

Designing personalised cancer treatments

The concept of personalised medicine for cancer is not new. It arguably began with the attempts by Salmon and Hamburger to produce a viable cellular chemosensitivity assay in the 1970s, and continues to this day. While clonogenic assays soon fell out of favour due to their high failure rate, other cellular assays fared better and although they have not entered widespread clinical practice, they have proved to be very useful research tools. For instance, the ATP-based chemosensitivity assay was developed in the early 1990s and is highly standardised. It has proved useful for evaluating new drugs and combinations, and in recent years has been used to understand the molecular basis of drug resistance and sensitivity to anti-cancer drugs. Recent developments allow unparalleled genotyping and phenotyping of tumours, providing a plethora of targets for the development of new cancer treatments. However, validation of such targets and new agents to permit translation to the clinic remains difficult. There has been one major disappointment in that cell lines, though useful, do not often reflect the behaviour of their parent cancers with sufficient fidelity to be useful. Low passage cell lines - either in culture or xenografts are being used to overcome some of these issues, but have several problems of their own. Primary cell culture remains useful, but large tumours are likely to receive neo-adjuvant treatment before removal and that limits the tumour types that can be studied. The development of new treatments remains difficult and prediction of the clinical efficacy of new treatments from pre-clinical data is as hard as ever. One lesson has certainly been that one cannot buck the biology - and that understanding the genome alone is not sufficient to guarantee success. Nowhere has this been more evident than in the development of EGFR inhibitors. Despite overexpression of EGFR by many tumour types, only those with activating EGFR mutations and an inability to circumvent EGFR blockade have proved susceptible to treatment. The challenge is how to use advanced molecular understanding with limited cellular assay information to improve both drug development and the design of companion diagnostics to guide their use. This has the capacity to remove much of the guesswork from the process and should improve success rates.

Prediction of chemotherapeutic response in unresectable non-small-cell lung cancer (NSCLC) patients by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2- (4-sulfophenyl)-2H-tetrazolium (MTS) assay

BACKGROUND

Selecting chemotherapy regimens guided by chemosensitivity tests can provide individualized therapies for cancer patients. The 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H- tetrazolium, inner salt (MTS) assay is one in vitro assay which has become widely used to evaluate the sensitivity to anticancer agents. The aim of this study was to evaluate the clinical applicability and accuracy of MTS assay for predicting chemotherapeutic response in unresectable NSCLC patients.

METHODS

Cancer cells were isolated from malignant pleural effusions of patients by density gradient centrifugation, and their sensitivity to eight chemotherapeutic agents was examined by MTS assay and compared with clinical response.

RESULTS

A total of 37 patients participated in this study, and MTS assay produced results successfully in 34 patients (91.9%). The sensitivity rates ranged from 8.8% to 88.2%. Twenty-four of 34 patients who received chemotherapy were evaluated for in vitro-in vivo response analysis. The correlation between in vitro chemosensitivity result and in vivo response was highly significant (P=0.003), and the total predictive accuracy, sensitivity, specificity, positive predictive value, and negative predictive value for MTS assay were 87.5%, 94.1%, 71.4%, 88.9%, and 83.3%, respectively. The in vitro sensitivity for CDDP also showed a significant correlation with in vivo response (P=0.018, r=0.522).

CONCLUSION

MTS assay is a preferable in vitro chemosensitivity assay that could be use to predict the response to chemotherapy and select the appropriate chemotherapy regimens for unresectable NSCLC patients, which could greatly improve therapeutic efficacy and reduce unnecessary adverse effects.

Predicting efficacy of cancer cell killing under hypoxic conditions with single cell DNA damage assay

The activity of anticancer drugs determined under normal conditions cannot accurately reflect true drug efficacy in a patient, as a tumor is often under low oxygen (hypoxia) conditions. In addition, patient responses to the same therapy can be drastically different due to tumor heterogeneity. This paper describes the use of single cell halo assay for detection and quantification of DNA damage induced by anticancer drugs or radiation under hypoxic conditions. By combining classical halo assay and state-of-the-art microfabrication techniques, this single cell approach allows drug and radiation responses of cancer cells to be determined without population interference. The results from single cell assay indicate a diminished level of DNA damage at hypoxic conditions compared with those at normal conditions at the same drug concentrations or radiation dose, suggesting in vitro preclinical studies of drug and radiation activity can be performed under conditions that mimic physiological conditions of tumors and without population interference.

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

AIM

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.

METHODS

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).

RESULTS

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%).

CONCLUSION

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.

The predictive value of epidermal growth factor receptor expression for sensitivity to vinorelbine in breast cancer

Breast cancer patients with positive epidermal growth factor receptor (EGFR) expression have significantly worse post-relapse prognosis than patients with negative EGFR expression. Vinorelbine (NVB) is usually reserved as a salvage therapy after anthracyclines and taxanes in patients with breast cancer. To see whether EGFR expression has a predictive value in NVB-mediated effect on human breast cancer cells, we examined 50 primary breast cancer samples. Of these, 42% were found to be NVB sensitive by ATP-tumour chemosensitivity assay. Sensitivity was correlated with EGFR expression level (p = 0.001). To dynamically examine EGFR's effect on NVB sensitivity in breast cancer cells, we used the real-time cell electronic sensing system with EGFR-positive and EGFR-negative breast cancer cell lines, MCF-7 and MDA-MB-435s, respectively. MCF-7 is NVB sensitive, while MDA-MB-435 is NVB resistant. NVB-induced cytotoxicity to MCF-7 can be partly reversed with inhibitory anti-EGFR antibody. NVB up-regulated EGFR expression in MCF-7 cells, which affects ERK1/2 phosphorylation. This cellular response mechanism may cause greater input to non-lethally damaged cells. These data suggest that EGFR expression can be used as a prognostic factor for breast cancer sensitivity to NVB, which could help identify appropriate treatments for breast cancer.

Isolation and culture of colon cancer cells and cell lines

The preparation of cells from heavily contaminated tissue is challenging. It is usually best to avoid such specimens if possible, but for the study of colorectal and some other tumours, it is inevitable that this must be overcome. The best methods seem to use a combination of (1) debridement of necrotic or infected areas of the tumour, (2) enzymatic dissociation in the presence of antibiotics, (3) density centrifugation to remove debris, and (4) extensive washing of the tumour-derived cells prior to their use in cell culture methods. It is possible to obtain cells from up to 80-90% tumours with careful technique and cooperation from the clinical team.

Human glioma demonstrates cell line specific results with ATP-based chemiluminescent cellular proliferation assays

Alteration of tumor cell growth kinetics is the goal of nearly all current or proposed therapies for human neoplasms. The adenosine triphosphate (ATP) chemiluminescent assay has been used for some time as a surrogate marker of in vitro cell growth. Here we present data showing that three human glioblastoma cell lines (U87, U251, G55) demonstrate significantly different cell number to luminescence relationships when subjected to this assay. We plated progressively increasing numbers of cells per well; from 1000 to 50,000 were grown in Dulbecco's modified Eagle's medium without serum and cultured for 6 hours. Cells were then lysed and subjected to the chemiluminescent assay to measure ATP levels and a linear relationship between cell number and measured luminescence was found. Despite this, we found that the slope of the regression line (β) varied markedly between different cell lines (U251 [β = 0.968 ± 0.3] vs. U87 [β = 0.772 ± 0.2] vs. G55 [β = 0.757 ± 0.2]; p < 0.0001), suggesting a difference in ATP luminescence per cell between these cell lines. Thus, we have demonstrated that luminescence values are internally linear within a given cell population, but luminescence level per cell varies significantly between different glioma cell lines. Our findings suggest that different glioma cell lines have unique levels of ATP per cell.

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.

Predictive value of MTT assay as an in vitro chemosensitivity testing for gastric cancer: One institution’s experience

AIM: To investigate the predictive clinical value of in vitro 3-(4,5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide (MTT) assay for directing chemosensitivity in patients with gastric cancer.

METHODS: Results of a total of 353 consecutive patients with gastric cancer treated with MTT-directed chemotherapy or physician’s empirical chemotherapy from July 1997 to April 2003 were reviewed and analyzed retrospectively.

RESULTS: The overall 5-year survival rate of MTT-sensitive group (MSG) and control group (CG) was 47.5% and 45.1%, respectively. The results of subgroup analysis with Cox proportional-hazards model were favorable for the MSG-sensitive group. However, no statistically significant difference in survival rate was observed between the two groups.

CONCLUSION: Individualized chemotherapy based on in vitro MTT assay is beneficial, but needs to be confirmed by further randomized controlled trials.

Telomerase activity is not a key determinant of sensitivity to standard cytotoxic drugs in human esophageal carcinoma cell lines

The aim of the present study was to investigate if basal telomerase activity levels may predict sensitivity to cytotoxic drugs in a panel of human esophageal carcinoma cell lines. The TRAPeze telomerase detection assay was used to investigate telomerase activity in the cell lines. Cytotoxic drug sensitivity for 20 standard cytotoxic agents was assessed using the fluorometric microculture cytotoxicity assay (FMCA). Telomerase activity was detected in all cell lines with a broad range of activity levels. Drug sensitivity also varied considerably between the cell lines. Except for a P value towards a correlation between mitoxantrone and telomerase activity (P=0.054), no statistically significant correlation was found between telomerase activity levels and sensitivity to investigated drugs, including key drugs such as cisplatin (P=0.9), 5-fluorouracil (P=0.8) and doxorubicin (P=0.54). We therefore conclude that basal telomerase activity level is not a key determinant of sensitivity to standard cytotoxic drugs in esophageal carcinoma cell lines.

Tumor transcriptome reveals the predictive and prognostic impact of lysosomal protease inhibitors in non-small-cell lung cancer

PURPOSE

Insight into clinical response to platinum-based chemotherapy (PBC) in non-small-cell lung cancer (NSCLC).

METHODS

Matched tumor and nontumor lung tissues from PBC-treated NSCLC patients (four nonresponders and four responders) and tumor tissue from an independent test set (four nonresponders and four responders), were profiled using microarrays. Lysosomal protease inhibitors SerpinB3 and cystatin C were highly correlated with clinical response and were further evaluated by immunohistochemistry in PBC-treated patients (36 prechemotherapy and 13 postchemotherapy). Investigation of the pathogenic and prognostic significance of SerpinB3 was performed in 251 primary tumors, with 64 regional lymph node pairs, from chemotherapy-naïve NSCLC patients using immunohistochemistry.

RESULTS

Bioinformatic analyses of gene expression in the training set identified a gene set (n = 17) that separated all patients in the training and test sets (n = 16) according to response in hierarchical clustering. Transcriptome profiling revealed that SerpinB3 mRNA was highly correlated with degree of response (r = -0.978; P < .0001) and was a clear outlier (nonresponders:responders > 50-fold). SerpinB3 protein expression was correlated with clinical response in PBC-treated NSCLC patients (P = .045). Expression of SerpinB3 and cystatin C, relative to the target, protease cathepsin B, was independently predictive of response (odds ratio, 17.8; 95% CI, 2.0 to 162.4; P = .01), with an accuracy of 72%. High SerpinB3 expression levels, invariably associated with chemoresistance, had contrasting prognostic impact in untreated squamous cell carcinomas (hazard ratio [HR], 0.43; 95% CI, 0.18 to 0.93) or adenocarcinomas (HR, 2.09; 95% CI, 1.03 to 4.72).

CONCLUSION

This provides the first comprehensive molecular characterization of clinical responsiveness to PBC in NSCLC and reveals the predictive and prognostic impact of two lysosomal protease inhibitors, potentially representing novel targets for NSCLC therapeutics.

Suppression of primary breast, colon, gastric and bladder cancers cell growth in vitro by CKBM, a natural product

CKBM is a product composed of natural ingredients and had been shown to possess certain anti-cancer effects in vitro and in vivo. The aim of the present study is to analyze the chemosensitivity in the treatment of primary colon, breast, gastric and bladder cancer cells by CKBM. A total of 77 patients with cancers of breast, colon, stomach or bladder were included in the present study. Primary cancer cells were isolated from the surgical removed tumors and treated with various dosages of CKBM for 5 days. ATP is then extracted and measured by luminescence assay. CKBM treatment inhibited primary colon, breast, gastric and bladder cancer growth dose-dependently. The IC values were smaller from tumor cells at early stages, when compared with the ones at later stages. The present study strongly indicated that CKBM exerted cytotoxic effect on primary cancer cells.

Ex vivo characterization of XR11576 (MLN576) against ovarian cancer and other solid tumors

XR11576 (MLN576) is a novel monophenazine with a mechanism of action that includes interaction with both topoisomerase (Topo) I and II. The aim of this study was to evaluate its cytotoxicity against fresh tumor cells taken from patients with a variety of solid tumors. Cells were obtained from 89 patients and exposed for 6 days to XR11576 alone, or in combination with doxorubicin, cisplatin, treosulfan, paclitaxel or vinorelbine. Cell survival was measured using the ATP-Tumor Chemosensitivity Assay (ATP-TCA). Immunohistochemical staining of Topo I, Topo IIalpha and MDR1 was performed on paraffin-embedded blocks in those tumors for which tissue was available (n = 49). Overall, the median IC90 and IC50 values of XR11576 in tumor-derived cells were 242 and 110 nM, respectively. In all samples XR11576 was more potent than the other cytotoxics tested. Breast and gynecological malignancies were most sensitive to XR11576, while the potency of this compound was slightly attenuated in gastrointestinal tumors, in which the median IC90 and IC50 values were 308 and 212 nM, respectively. Cases of synergism were identified when combining XR11576 with vinorelbine (nine of 30 samples) and doxorubicin (12 of 38 samples), while the addition of paclitaxel resulted in an antagonistic effect (CI50>1.2) in 38 of 42 tumors. A very modest correlation by linear regression analysis was found between the intensity of MDR1 staining and the IC50 of XR11576 (r = 0.311, p = 0.0312), but not with the IC90 (r = 0.247, NS). These data support the rapid introduction of XR11576 to clinical trials and suggest that it may be effective against a broad spectrum of tumor types.

Feasibility of chemosensitivity testing in soft tissue sarcomas

BACKGROUND: Soft tissue sarcomas comprise less than 1% of all solid malignancies. The presentation and behavior of these tumors differs depending on location and histological characteristics. Standard therapy consists of complete surgical resection in combination with adjuvant radiotherapy. The role of chemotherapy is not clearly defined and is largely restricted to clinical trials. Only a limited number of agents have proved to be effective in soft tissue sarcomas. The use of doxorubicin, epirubicin and ifosfamide allowed response rates of more than 20%. In addition, recent chemotherapy trials did not demonstrate any significant differences in efficacy for various histological subtypes. METHODS: The objective of this study was to gain additional information about the chemosensitivity of soft tissue sarcomas to seven 7 different chemotherapy agents as single drugs and 4 combinations. Therefore we used an established ATP based in-vitro testing system and examined 50 soft tissue sarcomas. Chemosensitivity was assessed using a luciferin-luciferase-based luminescence assay providing individual chemosensitivity indices for each agent tested. RESULTS: The sensitivity varied widely according to the histological subtypes. The tumors state of cellular dedifferentiation played a crucial role for the efficiency of the chemotherapeutic agents. The sensitivity also depended on the presentation of the sarcoma as a primary or recurrent tumor. The highest sensitivity was demonstrated for actinomycin D as a single agent, with 74% of the tumor samples exhibiting a high-grade sensitivity (20% low sensitivity, no resistance). The combination of actinomycin D and ifosfamide yielded a high sensitivity in 76% (2% resistance). Doxorubicin as a mono-therapy or in combination with ifosfamide achieved high sensitivity in 70% and 72%, respectively, and resistance in 6% of the samples. CONCLUSION: Chemosensitivity testing is feasible in soft tissue sarcomas. It can be used to create sensitivity and resistance profiles of established and new cytotoxic agents and their combinations in soft tissue sarcomas. Our data demonstrate measurable discrepancies of the drug efficiency in soft tissue sarcomas, sarcoma subtypes and tumor recurrencies. However, current therapeutic regime does not take this in consideration, yet.

The ex vivo characterization of XR5944 (MLN944) against a panel of human clinical tumor samples

XR5944 (MLN944) is a novel DNA targeting agent with potent antitumor activity, both in vitro and in vivo, against several murine and human tumor models. We have used an ATP-tumor chemosensitivity assay to assess the ex vivo sensitivity of a variety of solid tumors (n = 90) and a CCRF-CEM leukemia cell line selected with XR5944. Differences in gene expression between the parental CCRF-CEM and the resistant subline were investigated by quantitative reverse transcription-PCR. Immunohistochemistry for topoisomerases I and IIα and multidrug resistance (MDR1) protein was done on those tumors for which tissue was available (n = 32). The CCRF-CEM XR5944 line showed increased mRNA levels of MDR1, major vault protein, and MDR-associated protein 1 compared with the parental line, whereas the expression of topoisomerases I, IIα, and IIβ was essentially unchanged, suggesting that XR5944 is susceptible to MDR mechanisms. The median IC90 and IC50 values for XR5944 in tumor-derived cells were 68 and 26 nmol/L, respectively, 6-fold greater than in resistant cell lines. XR5944 was 40- to 300-fold more potent than the other cytotoxics tested, such as doxorubicin, topotecan, and paclitaxel. Breast and gynecologic malignancies were most sensitive to XR5944, whereas gastrointestinal tumors showed greater resistance. A positive correlation (r = 0.68; P &lt; 0.0001) was found between the IC50 values of XR5944 and P-glycoprotein/MDR1 staining but not with either topoisomerase I or IIα immunohistochemistry index. These data support the rapid introduction of XR5944 to clinical trials and suggest that it may be effective against a broad spectrum of tumor types, especially ovarian and breast cancer.

Ex vivo reversal of chemoresistance by tariquidar (XR9576)

The expression of P-glycoprotein (P-gp) has been demonstrated to confer resistance to several anticancer drugs, including anthracyclines, taxanes and vinca alkaloids. Tariquidar is a novel inhibitor of P-gp that has been shown to reverse resistance to cytotoxic drugs in tumor cell lines and mouse xenografts. We have used an ATP-based chemosensitivity assay (ATP-TCA) to compare the activity of cytotoxic drugs in combination with tariquidar against a variety of solid tumors (n = 37). The expression of P-gp was determined in a subset of solid tumor samples by immunohistochemistry (n = 16). Resistance was seen in 20 of 37 (54%) tumors tested with doxorubicin, in 27 of 34 (79%) samples tested with paclitaxel and 17 of 31 (55%) with vinorelbine. Tariquidar alone showed no activity over a wide range of concentrations up to 2 microM (n = 14). The median IC90s for doxorubicin, paclitaxel and vinorelbine, alone were 2.57, 27.4 and 15.5 microM. These decreased to 1.67 (p<0.0005), 20.6 (p<0.05) and 9.5 microM (p<0.001), respectively, in combination with tariquidar. Tariquidar also significantly decreased resistance in 14 of 20 (70%), six of 27 (22%) and six of 17 (35%) samples tested with doxorubicin, paclitaxel and vinorelbine, respectively. Immunohistochemical staining for P-gp was positive in nine of 16 (56%) samples and in all of these cases addition of tariquidar improved the activity of the cytotoxic. The results show that tariquidar is able to decrease resistance in a number of solid tumors resistant to cytotoxic drugs known to be P-gp substrates. These data support the introduction of tariquidar in combination with chemotherapy to clinical trials of patients expressing P-gp.

Clonogenic assay with established human tumour xenografts: correlation of in vitro to in vivo activity as a basis for anticancer drug discovery

Pluripotent cells can be grown in clonogenic assays. The tumour stem-cell fraction, which accounts for <0.4% of the total cells, and which is considered the most relevant cell type in the development of metastases and recurrences, is able to divide and to form colonies in a semisolid matrix (agar or methylcellulose). Major applications of the tumour clonogenic assay (TCA) are chemosensitivity testing of tumours and xenografts, and for assessments within drug discovery programmes. Of critical relevance for the usefulness of the TCA is whether it can predict sensitivity or resistance towards clinically used agents. When we compared the response of human tumours established as xenografts in nude mice in the TCA in vitro to that of the clinical response, 62% of the comparisons for drug sensitivity, and 92% of the comparisons for drug resistance were correct. The same percentage of true/false observations was found when tumours were tested after serial passage in nude mice in the TCA in vitro and their response compared to in vivo activity in corresponding xenografts (60% and 90%, respectively). The highest correct predictive values were, however, found when the clinical response of tumours was compared to their explants established in the nude mouse and treated in vivo. Of 80 comparisons performed, we observed a correct prediction for tumour resistance in 97% and for tumour sensitivity in 90%. In our opinion, the TCA with established human tumour xenografts has an important role in current drug discovery strategies. We therefore included the TCA as secondary assay in our approach to anticancer drug discovery and found that a number of novel agents were active; these are now in advanced preclinical development or clinical trials. Thus, the tumour clonogenic assay has proven predictive value in the chemosensitivity testing of standard and experimental anticancer drugs.

Combination chemotherapy in advanced gastrointestinal cancers: ex vivo sensitivity to gemcitabine and mitomycin C

Advanced or metastatic disease is common in both oesophagogastric and colorectal cancers, with poor 5-year survival despite palliative chemotherapy. We have investigated the sensitivity of gastrointestinal tumours to gemcitabine in combination with mitomycin C (GeM), using a modified ex vivo ATP-based tumour chemosensitivity assay (ATP-TCA). Tumour material from 41 colorectal and 22 oesophagogastric cancers were assessed. The GeM combination showed variable but definite activity in most of the samples tested. The results show that GeM achieves >95% inhibition at concentrations within the range achievable clinically in 60% of colorectal tumours (21 out of 35) and 38% of oesophagogastric tumours (five out of 13) tested. We did not identify any significant difference in sensitivity using concurrent or sequential exposure of tumour-derived cells to these two drugs. The results from this study suggest that GeM may be a useful combination in the treatment of advanced gastrointestinal malignancy.