Novartis announced recently that it received marketing approval from the US Food and Drug Administration (FDA) for zoledronic acid(Drug information on zoledronic acid) (Zometa), a new generation intravenous bisphosphonate for the treatment of hypercalcemia of malignancy. Clinical trials demonstrated a statistically significant difference in the number of complete responses among patients receiving zoledronic acid compared to those receiving the current standard treatment, pamidronate(Drug information on pamidronate) (Aredia). Response was measured by a normalization of serum calcium by day 10.
"It is very encouraging to know that we have a new, effective treatment for hypercalcemia of malignancy in the United States for such an important and potentially life-threatening cancer complication," said lead investigator Pierre Major, MD, medical oncologist at Hamilton Regional Cancer Center and associate professor in the department of medicine at McMaster University, Hamilton, Ontario, Canada. "It is likely that with its efficacy and shorter infusion time, Zometa should replace Aredia as the gold standard for hypercalcemia of malignancy."
Trial Data
The clinical data upon which the filing and subsequent approval were based were from two pivotal studies that compared zoledronic acid to pamidronate. The two multicenter trials enrolled 287 patients, of which 275 were evaluable. Patients were randomized to receive a single dose of either zoledronic acid at 4 mg or 8 mg or a single dose of pamidronate at 90 mg. By day 10 of treatment, serum calcium concentrations were normalized in 88% of patients treated with zoledronic acid at 4 mg. Among patients treated with pamidronate, only 70% achieved normalized serum calcium concentrations (P = .002). The results of this trial were published in the January 15, 2001, issue of the Journal of Clinical Oncology.
The median duration of complete response among patients taking zoledronic acid at 4 mg was 32 days vs 18 days for patients receiving pamidronate. Time to relapse was 30 days for the zoledronic acid arm and 17 days for the pamidronate arm (P < .05). There was no difference in outcome between the 4-mg and 8-mg dose arms.
Adverse Events
The most common adverse events associated with the use of zoledronic acid included a flu-like syndrome (fever, arthralgias, myalgias, skeletal pain), gastrointestinal reactions, anemia, insomnia, and dyspnea. Occasionally, patients experienced electrolyte and mineral disturbances, such as low serum phosphate, calcium, magnesium, and potassium.
