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Amifostine reduced adverse events and improved radiotherapy response
Analysis shows amifostine reduced grade-2 and -3 acute xerostomia by 76% compared with placebo or observation.
A meta-analysis revealed that amifostine (Ethyol, MedImmune) reduces common adverse events associated with radiation therapy. It also indicated that the drug does not protect tumors from radiation.
“This meta-analysis not only confirms the lack of tumor protection with the use of amifostine, but also proved that patients receiving this drug were able to achieve higher levels of complete response,” wrote André Deeke Sasse, MD, radiation oncologist at the Brazilian Nucleus of Oncology-based Evidence in Sao Paolo, and colleagues.
Adverse events
Sasse and colleagues evaluated amifostine’s role in preventing the most common radiotherapy adverse events: mucositis, acute and late xerostomia, dysphagia, pneumonitis, cystitis and dermatitis.
They analyzed 14 randomized, controlled clinical trials conducted between 1973 and 2005, identifying 1,451 patients who received either radiotherapy alone or radiotherapy plus amifostine. Six studies focused on head and neck tumors, four focused on pelvic tumors and six focused on thoracic tumors. The dose of amifostine ranged from 150 mg/m2 to 340 mg/m2.
Twelve of the 14 trials compared amifostine with placebo or observation. Amifostine reduced the incidence of grade-3 or -4 oral mucositis by 63% (P < .001). In five head and neck cancer studies, amifostine reduced grade-3 and -4 mucositis by 56% (P < .001).
Six studies evaluated esophagitis in patients with thoracic tumors. Amifostine reduced the incidence of this adverse event by 62% (P < .001). Additionally, three studies showed an 83% reduction in proctitis for patients with pelvic tumors (P = .0002).
Four of six head and neck cancer studies reported acute xerostomia and two of those studies reported late xerostomia. Amifostine reduced the incidence of grade-2 and -3 acute and late xerostomia by 76% and 67%, respectively, compared with placebo or observation (P < .001 for both variables).
In three of six thoracic radiotherapy studies, amifostine reduced the chance of developing pneumonitis by 85% (P < .001). The four pelvic radiotherapy studies showed that amifostine reduced the incidence of developing cystitis by 83% (P < .001).
Excessive heterogeneity among studies precluded researchers from performing a meta-analysis on dermatitis.
Treatment response
Nine of the 14 studies reported treatment response rates. Partial response rates were similar among the three radiotherapy groups: head and neck, pelvic and thoracic. Patients taking amifostine experienced superior complete response rates (P = .02). However, the researchers found no statistical difference in overall response rates among the groups, nor was there a correlation between amifostine use and relapse rates among the five studies that presented data on this endpoint.
“Thus we conclude that there is sufficient evidence to state that amifostine does not protect the tumor,” they wrote in the International Journal of Radiation Oncology, Biology and Physics.
Sasse and colleagues also collected data on amifostine toxicity in 10 of the 14 studies. Nausea and vomiting commonly accompany amifostine administration, and the incidence of grade-3 or -4 nausea and vomiting was higher for patients using amifostine. Both of those adverse events were effectively controlled with standard anti-emetics.
“Our research shows that adding amifostine to radiation therapy helps reduce [adverse events] while at that same time making the radiation treatments more effective at killing the cancer cells,” Sasse said. “We recommend that patients undergoing radiation therapy for cancer ask their doctor about adding amifostine to their treatment.” – by Danielle Antonetti
For more information:
- Sasse AD, de Oliveira Clark LG, Sasse EC, Clark OA. Amifostine reduces side effects and improves complete response rate during radiotherapy: results of a meta-analysis. Int J Radiat Oncol Biol Phys. 2006;64:784-791.