Stability of solutions of antineoplastic agents during preparation and storage for in vitro assays. III. Antimetabolites, tubulin-binding agents, platinum drugs, amsacrine, L-asparaginase, interferons, steroids and other miscellaneous antitumor agents

E. coli-Derived L-Asparaginase Retains Enzymatic and Cytotoxic Activity In Vitro for Canine and Feline Lymphoma after Cold Storage

Background. L-asparaginase is effective in treating canine and feline lymphoma, however chemotherapy poses a significant financial cost to veterinary clients, limiting therapy for many pets. Single dose vials result in significant drug wastage, and drug shortages limit consistent availability for pets. Hypothesis. E. coli-derived asparaginase retains enzymatic and antineoplastic activity in canine and feline lymphoma cells after cold storage. Methods. E. coli-derived asparaginase was cold-stored: refrigeration (7–14 days) and freezing (14 days–six months, one to three freeze/thaw cycles). Enzymatic activity of asparaginase was measured via a modified asparagine assay. Effects of cold-stored asparaginase on cell proliferation and cytotoxicity were measured in feline (MYA-1, F1B) and canine (17–71, OSW) lymphoma cells. Results. Cold-stored E. coli-derived asparaginase retains antineoplastic activity in all four cell lines tested. Cold-stored E. coli-derived L-asparaginase depletes asparagine and retains enzymatic activity. Duration of refrigeration, duration of freezing, and number of freeze-thaw cycles have minimal effect on asparaginase enzyme activity. Conclusions and Clinical Importance. This study establishes a scientific basis for long-term cold storage of reconstituted E. coli-derived asparaginase that may result in better utilization of limited drug resources and improve financial feasibility of E. coli-derived asparaginase as a therapeutic option for pets with lymphoma.

Therapy-induced carboplatin-DNA adduct levels in human ovarian tumours in relation to assessment of adduct measurement in mouse tissues

Despite an increasing understanding of the molecular mechanisms by which platinum drug DNA adducts interact with cellular processes, the relationship between adduct formation in tumours and clinical response remains unclear. We have determined carboplatin-DNA adduct levels in biopsies removed from ovarian cancer patients following treatment. Reliability of DNA adduct measurements in tissues samples were assessed using experimental animals. Platinum-DNA adduct levels were measured using inductively coupled plasma mass spectrometry (ICP-MS) and plasma drug concentrations determined by atomic absorption spectrometry (AAS). Adduct levels in tissues and plasma pharmacokinetics were determined in Balb/c mice exposed to platinum drugs. Comparisons of adduct levels in tumour and normal tissue were made in nu/nu mice carrying human neuroblastoma xenografts. At 30 min post-cisplatin administration, adduct levels in DNA from kidney and liver were approximately 10- and 6-fold higher than spleen or tumour. By 60 min, levels in liver and kidney, but not spleen or tumour, had fallen considerably. Carboplatin showed high adduct levels only in kidney. Adduct levels in tumour xenografts were comparable to those induced in vitro with similar drug exposures. In clinical samples removed 6h after drug administration, adduct levels ranged from 1.9 to 4.3 and 0.2 to 3.6 nmol Pt/g DNA for tumour biopsies and peripheral blood mononuclear cells, respectively. No correlation was apparent between these two data sets. The present results demonstrate that reliable measurements of adducts in clinical tumours are feasible. Future results should provide insight into drug resistance.

5-Fluorouracil induces apoptosis in human colon cancer cell lines with modulation of Bcl-2 family proteins

Recently, apoptosis has been implicated as one of the end points of cells exposed to chemotherapeutic agents. The p53 and Bcl-2 family of proteins are involved in chemotherapy-induced apoptosis, but in a cell type-dependent manner. We sought to determine the roles played by the p53 and Bcl-2 family of proteins in 5-fluorouracil (5-FU)-induced apoptosis of human colon cancer cell lines. We first studied the p53 genetic and functional status, and then 5-FU, at inhibitory concentration of 50% (IC50) doses, was used to induce apoptosis, which was confirmed by morphological analysis and enzyme-linked immunosorbent assay (ELISA). Bcl-2, Bcl-X(L), Bax, Bad, Bak and p53 protein expression was analysed by Western blotting. Using five human colon cancer cell lines, we found that equitoxic (IC50) doses of 5-FU induced apoptosis in both wild-type p53 and mutant p53 cells. Analysis of the steady-state levels of Bcl-2 family proteins showed high expression of Bcl-X(L) in all of the cell lines except Colo320. Bcl-2 was expressed in two of them. Bax presented with the lowest basal expression and Bad showed homogeneous expression. On the other hand, Bak expression varied more than fivefold among these cells. In cells containing wild-type p53 (e.g. LoVo), 5-FU-induced apoptosis was accompanied by increased expression of Bax and Bak without consistent modulation of other bcl-2 family proteins. In contrast in cells containing mutant p53 (e.g. DLD1), Bak expression was remarkably increased. There was a significant correlation between chemosensitivity and Bcl-X(L) to Bax ratio, rather than Bcl-2 to Bax. In conclusion, these results suggest that some members of the Bcl-2 family of proteins, in human colon cancer cell lines, are modulated by 5-FU and that the ratio of Bcl-X(L) to Bax may be related to chemosensitivity to 5-FU.

5-Fluorouracil release from copolymeric hydrogels of itaconic acid monoester. I. Acrylamide-co-monomethyl itaconate

The aim of this work was to test the application of new copolymeric poly (acrylamide-co-monomethyl itaconate) (A/MMI) hydrogels to 5-fluorouracil (5-FU) release. Three different compositions of copolymers have been studied, 90A:10MMI 75A:25MMI and 60A:40MMI. The equilibrium swelling degree in saline solution was between 76 and 80% depending on the copolymer composition. 5-FU, as the sodium salt, was trapped in the gels by including it in the feed mixture of polymerization. The swelling kinetics of the hydrogels in saline solution were studied at four temperatures, and the diffusion coefficient and the activation energy of the process were obtained. The 5-FU release as a function of temperature and disc load was studied; the diffusion coefficient and the activation energy of the release process were also obtained. The diffusion studies follow Fick's second law.

Release of 5-fluorouracil from poly(acrylamide-co-monopropyl itaconate) hydrogels

The aim of this work was to test the application of copolymeric poly(acrylamide-co-monopropyl itaconate) (A-MPI) hydrogels on the release of 5-fluorouracil (5-FU). The equilibrium degree of swelling in saline solution was 83 +/- 2%. 5-FU, as the sodium salt, was trapped in gels by placing it in the polymerization feed mixture. The diffusion coefficients for both swelling of the gels and the release of 5-FU were determined, in addition to the activation energies for both processes. To determine the applicability of these copolymers, A-MPI (75:25) gel was subcutaneously implanted in rats and the drug plasma concentration was determined by HPLC.

Enhanced ex vivo drug sensitivity testing of chronic lymphocytic leukaemia using refined DiSC assay methodology

Ex vivo drug sensitivity testing is of considerable benefit in aiding the choice of optimum chemotherapy for leukaemia patients, especially when several therapeutic options exist, e.g. for relapsed chronic lymphocytic leukaemia (CLL). We have used the Differential Staining Cytotoxicity (DiSC) assay to assess drug sensitivity in CLL for over a decade and here present many methodological improvements, including depositing multiple samples per microscope slide and performing a rapid LC90 evaluation. Using these improvements, 412/450 specimens were successfully tested. Failures were mainly due to extended specimen transit time. All 38 drugs tested exhibited dose-dependent cell kill and broad ranges of resultant LC90S were observed. Comparison of 2- and 4-day incubations underscored a requirement for 4-day incubation with pentostatin and steroids. The rapid, simple and streamlined DiSC assay presented here can aid choice of optimum therapy, identify novel anticancer agents and be used to study drug resistance.

Stability and compatibility of a mixture of the anti-cancer drugs etoposide, cytarabine and daunorubicine for infusion

We evaluated (i) the stability of a mixture of the three anti-cancer agents used for the treatment of leukemia, namely etoposide, cytarabine and daunorubicine, in 5% glucose, and (ii) its compatibility towards various materials during an infusion protocol as performed for therapeutic purposes in hospital practice. Etoposide and cytarabine were assayed by high-performance liquid chromatography with a C18 type column and UV detection. Daunorubicine was assayed by visible spectrophotometry. The stability study showed all three anti-cancer drugs to be stable in 5% glucose solution, both alone and mixed. Best conservation was obtained by keeping bottles containing the mixture in the dark at room temperature. During the infusion protocol used in clinical practice, etoposide, cytarabine and daunorubicine were stable and compatible with the various materials present in the infusion sets and extension tubing (polyvinyl chloride, polyethylene) and catheters (silicone). Observed variations in concentration did not exceed 10% of initial concentrations of each drug, though we would advocate changing infusion sets and extension tubing daily.

Influence of degree of crosslinking on 5-fluorouracil release from poly(2-hydroxyethyl methacrylate) hydrogels

Controlled release of 5-fluorouracil (5-FU) from poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogels with three different degrees of crosslinking is reported. The swelling kinetic of PHEMA hydrogels in water was studied at different disc thicknesses and temperatures, and the diffusion coefficient and activation energy of the process were obtained. The gels were loaded with 5-FU by immersing them in concentrated aqueous solutions of the drug. The 5-FU release was studied as a function of temperature, disc thickness, disc load and degree of crosslinking of the gels; the diffusion coefficient and activation energy of the release process were also obtained.