Related Experiment Video
Updated: Aug 30, 2026
Ex Vivo Treatment Response of Primary Tumors and/or Associated Metastases for Preclinical and Clinical Development of Therapeutics
Published on: October 2, 2014
Ex vivo analysis of topotecan: advancing the application of laboratory-based clinical therapeutics
R A Nagourney1, B L Sommers, S M Harper
1Rational Therapeutics, Inc., 750 East 29th Street, Long Beach, CA 90806, USA. robert.nagourney@rationaltherapeutics.com
Abstract:
Topotecan is currently approved for relapsed small-cell lung cancer and ovarian cancer. Topotecan's efficacy in the second-line setting and novel mechanism of action suggest broad antitumour activity. We utilised a clinically validated, cell-death, ex vivo assay in human tumour explants to examine the activity profile of topotecan alone and in combination with other antitumour agents. Serial dilutions of topotecan alone and in combination with other cytotoxic agents were applied to biopsy specimens of non-small-cell lung cancer (NSCLC) and breast, colon, and prostate cancers. Dose-response curves were interpolated to provide 50% lethal concentrations (LC(50)). The degree of synergy (by median effect) and normalised Z-scores (raw scores converted to relative activity distributed around the mean) were then computed. Single-agent activity was observed for topotecan in all four tumour types. In 57 chemotherapy-naive specimens, NSCLC revealed the highest activity, demonstrated by the lowest LC(50) value (0.26+/-0.06 microg ml(-1); P=0.002). Overall, previously treated and chemotherapy-naive specimens revealed no significant differences in mean LC(50)'s. Synergy was observed for several combinations, including topotecan plus cisplatin in prostate and for topotecan plus 5-fluorouracil in breast cancers. The Z-score analyses conducted suggest activity for previously unexplored drug regimens, including topotecan plus 5-fluorouracil, vinorelbine, and mitomycin-C in NSCLC and breast cancer. Phase II studies are underway to determine the degree to which these ex vivo findings will translate into improved clinical results.
Insights
Topotecan shows broad anticancer activity in various tumors, including non-small-cell lung cancer. Combinations like topotecan with cisplatin or 5-fluorouracil demonstrate synergistic effects, warranting further clinical investigation.
Area of Science:
- Pharmacology
- Oncology
- Cancer Research
Background:
- Topotecan is approved for relapsed small-cell lung cancer and ovarian cancer.
- Its mechanism suggests potential for broader anticancer applications.
- Ex vivo assays offer a method to predict clinical efficacy.
Purpose of the Study:
- To evaluate the ex vivo activity of topotecan across multiple human tumor types.
- To identify synergistic drug combinations with topotecan.
- To explore novel topotecan-based treatment regimens.
Main Methods:
- Utilized a validated ex vivo cell-death assay on human tumor explants.
- Tested topotecan alone and in combination with cytotoxic agents on non-small-cell lung cancer, breast, colon, and prostate cancer specimens.
- Calculated 50% lethal concentrations (LC50), synergy, and normalized Z-scores.
Main Results:
- Topotecan demonstrated single-agent activity in all tested tumor types.
- Non-small-cell lung cancer showed the highest sensitivity (lowest LC50).
- Synergistic activity was observed for topotecan plus cisplatin (prostate) and topotecan plus 5-fluorouracil (breast).
Conclusions:
- Topotecan exhibits broad ex vivo anticancer activity.
- Specific drug combinations show promising synergy.
- Findings support further clinical trials for topotecan-based therapies in various cancers.
