Combination 186Re-HEDP and cisplatin supra-additive treatment effects in prostate cancer cells.
Radionuclide therapy has proven to be an efficacious palliative treatment for metastatic prostate cancer. Its potential therapeutic possibilities may be substantially increased by combining it with effective radiosensitizing drugs.


METHODS
This study explores the radiosensitizing properties of cisplatin when combined with 186Re-labeled hydroxyethylidene diphosphonate (HEDP) in the treatment of R3327-MATLyLu prostate cancer cells in vitro. A concomitant incubation during 4 d, combining various concentrations of cisplatin (0, 0.42, 0.83 and 1.67 micromol/L) and 186Re-HEDP (0, 1.84 and 3.69 MBq/mL [0, 50 and 100 microCi/mL, respectively]) was followed by the determination of the cell numbers surviving and the replating of these cells in semisolid agar.


RESULTS
The surviving fraction of clonogenic tumor cells after combination treatment clearly showed synergism when analyzed by a panel of three different published analytical methods. In addition, analysis of variance demonstrated a significant interaction between radionuclide therapy and cisplatin-based chemotherapy (P < 0.001). Treatment with 186Re-HEDP and cisplatin by sequential incubation yielded similar, but never superior results.


CONCLUSIONS
It is concluded that radionuclide therapy in combination with cisplatin is able, in principle, to improve therapeutic success rate in metastatic prostate cancer in a more than additive way.
Geldof
A A
AA
Department of Nuclear Medicine, Academisch Ziekenhuis Vrije Universiteit, Amsterdam, The Netherlands.
de Rooij
L
L
Versteegh
R T
RT
Newling
D W
DW
Teule
G J
GJ
D000818:Animals; D002945:Cisplatin / Q000627:therapeutic use*; D003131:Combined Modality Therapy; D004354:Drug Screening Assays, Antitumor; D012968:Etidronic Acid / Q000627:therapeutic use*; D008297:Male; D009942:Organometallic Compounds; D011471:Prostatic Neoplasms / Q000628:therapy*; D011838:Radiation-Sensitizing Agents / Q000627:therapeutic use*; D011868:Radioisotopes / Q000627:therapeutic use*; D051381:Rats; D012211:Rhenium / Q000627:therapeutic use*; D014407:Tumor Cells, Cultured
D009942:Organometallic Compounds; D011838:Radiation-Sensitizing Agents; D011868:Radioisotopes; C101598:rhenium-186 HEDP; D012211:Rhenium; D012968:Etidronic Acid; D002945:Cisplatin