Protection against cisplatin induced neurotoxicity by ORG 2766: histological and electrophysiological evidence.

Prolonged administration of the anti-tumor agent cisplatin may cause a neuropathy in patients. In an animal model, too, neurotoxicity, as evidenced by a decrease in H-related sensory nerve conduction velocity (SNCV), can be induced by repetitive injections of cisplatin. In an attempt to further the insight into the effects of cisplatin on the peripheral nervous system a combined electrophysiological and histomorphological investigation was performed on 2 groups of 6 rats, treated with cisplatin for 7.5 weeks, and a control group (n = 6). Concomitant administration of ORG 2766, an ACTH(4-9) analog, was previously shown to prevent cisplatin neurotoxicity in this model and more recently in patients as well. One group of rats was therefore co-treated with this peptide during the complete treatment period. A marked decrease in SCNV was observed in cisplatin/saline treated rats, but not in cisplatin/ORG 2766 treated rats. Though no statistically significant difference was seen in the total number of myelinated fibers in the sural nerves of cisplatin treated rats, a decrease in the proportion of thick myelinated fibers was present in the cisplatin/saline treated rats. This shift in fiber distribution was absent in ORG 2766 co-treated animals. Mean internodal distances and g-ratios were not affected, and signs of axonal degeneration, or de- or remyelination were not observed.

Morphological and electrophysiological study of the effects of cisplatin and ORG.2766 on rat spinal ganglion neurons.

Eleven- to 12-wk-old rats were treated twice a week with cisplatin/saline or with cisplatin plus ORG.2766 during 12.5 wk. Cisplatin and ORG.2766 were administered at a final concentration of 0.04 mg/ml (i.p.) and 10 micrograms/ml (s.c.), respectively. Control animals were treated with saline. In this period the cisplatin-treated animals developed a peripheral neuropathy resulting in impairment of sensory functions. Estimates of the motor (MNCV) and sensory (SNCV) nerve conduction velocity were made after 0, 7.5, 10, and 12.5 wk. It appeared that the MNCV of the control, cisplatin-, and cisplatin plus ORG.2766-treated rats increased from 50 to 59 m/s. In contrast, the SNCV of the cisplatin-treated rats decreased significantly (P less than 0.001) from 63 to 56 m/s, whereas that of the control animals increased from 62 to 84 m/s. Rats which received cisplatin plus ORG.2766 showed an increase in SNCV up to control levels. After 12.5 wk the animals were perfused with a mixture of 1% paraformaldehyde and 1.25% glutaraldehyde in 0.05 M phosphate buffer. At the level of L5 and L6, 5 mm of spinal cord tissue and three dorsal root ganglia were removed and processed for electron microscopy. With the point-counting method the volume fraction (v/v) of somata and myelin in spinal ganglia was estimated. No significant change in the volume fraction of somata of the control (0.42), cisplatin (0.33)-, and cisplatin plus ORG.2766 (0.39)-treated rats was found. The same held true for the volume fraction of myelin of the control (0.53), cisplatin (0.59)-, and cisplatin plus ORG.2766 (0.58)-treated rats. In addition, the number of lysosomes per 100 microns 2 was estimated in spinal ganglion neurons and in spinal cord motor neurons of a total of 120 randomly chosen neurons. It was found that the number of lysosomes in the spinal ganglion neurons of the control animals was lower (10 per 100 microns 2) than in cisplatin-treated (30 per 100 microns 2) and in cisplatin plus ORG.2766-treated rats (28 per 100 microns 2) (P less than 0.05). No difference was observed in the number of lysosomes between cisplatin- and cisplatin plus ORG.2766-treated rats. The number of lysosomes in spinal cord tissue of cisplatin-treated rats (2.4 per 100 microns 2) did not differ from controls (0.1 per 100 microns 2) and from cisplatin plus ORG.2766-treated rats (0.8 per 100 microns 2).(ABSTRACT TRUNCATED AT 400 WORDS)

Vibration perception and thermoperception as quantitative measurements in the monitoring of cisplatin induced neurotoxicity.

In 20 ovarian cancer patients treated by cisplatin-based chemotherapy quantitative investigations of the vibration and the thermoperception were performed. Following the administration of cisplatin of 300 mg/m2 and more the vibration perception threshold (VPT) was shown to be significantly elevated in all patients, despite the absence of clinical symptoms and signs in a number of patients. The VPT returned within 8 months to its original level in the 2 patients who were followed after cessation of therapy (cumulative dose of cisplatin 450-525 mg/m2). The changes seen in hands and in feet were comparable. There was no significant difference between the left and the right hand side. Thermoperception thresholds did not change during the treatment period. This study shows that quantitative measurement of vibration perception thresholds in patients treated with cisplatin is a relatively simple, accurate and reliable technique. Measurement is only required at the hand. It is concluded that this technique is a valuable tool in the assessment of cisplatin neurotoxicity and may be used in the monitoring of drugs that claim to be of benefit in the prevention and treatment of this affliction.

Efficacy of the neuropeptide ORG.2766 in the prevention and treatment of cisplatin-induced neurotoxicity in rats.

In rats chronic systemic treatment with cisplatin results in a sensory neuropathy as evidenced by a reduction in the sensory conduction velocity in the sciatic nerve. Concomitant administration of the neurotrophic ACTH4-9 analog, ORG.2766, prevents the occurrence of the neuropathy. In addition, treatment with ORG.2766 stops further deterioration and improves recovery of an already established cisplatin-induced neuropathy. Furthermore, concomitant administration of ORG.2766 during a first cisplatin treatment period results in a better resistance against neurotoxicity in a second exposure period. Finally, ORG.2766 was shown not to hamper the anti-tumor effect of cisplatin in mice, carrying implanted tumor cells from a FMa human tumor line. These data are discussed in view of the potential clinical use of ORG.2766 in prevention and treatment of cisplatin-induced neuropathy.