Patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) who receive daily oral cyclophosphamide have increased bone marrow toxicity and tend to be hospitalized more often because of infections, than patients who receive the treatment intravenously.
Those findings were detailed in the report “Long-term outcomes of daily oral vs. pulsed intravenous cyclophosphamide in a non-trial setting in ANCA-associated vasculitis,” which was published in the journal Clinical Rheumatology.
Cyclophosphamide is routinely given for the treatment of AAV, either by daily oral or pulsed intravenous administration. While both treatment delivery methods have been shown to be equally effective, the intravenous route is thought to have less toxicity.
“In many centres in the UK, people with AAV who present to rheumatology receive [intravenous] therapy and those who present to nephrology receive [oral] therapy,” the researchers explained. But how this related to patient outcomes had not been addressed.
In an attempt to compare both drug delivery approaches in a real-life setting – including patients who would not meet clinical trial inclusion criteria – researchers studied a group of AAV patients treated with cyclophosphamide at the Nottingham University Hospitals NHS Trust from March 2007 to June 2013.
They compared different outcomes, including the risk of mortality, relapse, low levels of neutrophils (a group of cells of the immune system), and infections that required hospitalization.
The study included 114 patients – 57 patients received the therapy orally and 57 patients received it intravenously. Patients were followed for a mean period of 4.8 years.
Patient characteristics were markedly different between the two groups at baseline, “reflecting the clinical differences influencing whether patients would present to nephrology or rheumatology.” Those treated with cyclophosphamide orally were older and had more advanced renal involvement, two characteristics associated with worse outcomes.
Patients receiving oral cyclophosphamide had worse survival outcomes compared to those who received the intravenous treatment. But, after adjusting for age, sex and renal function, no differences in survival or relapse rates were found between the two methods of administering the drug.
Daily oral administration was associated with a significant increased risk of neutropenia (low neutrophils levels) and a tendency for higher hospital admission due to infections, but failed to reach statistical significance.
These findings add to previous studies showing that daily oral cyclophosphamide has higher toxicity to bone marrow, leading to lower white blood cell counts that put patients at risk for infections.
During the first year of follow-up, more than 20 percent of patients were hospitalized due to an infection, which “highlights the need for ongoing clinical vigilance during the treatment of this complex disease,” researchers concluded.