Lack of difference in acute nephrotoxicity of intravenous bisphosphonates zoledronic acid and ibandronate in women with breast cancer and bone metastases.
BACKGROUND
More than 50% of patients with advanced breast cancer develop bone metastases that may lead to multiple complications such as pathological fractures, bone pain or hypercalcaemia. The standard treatment, besides endocrine, targeted-therapy or chemotherapy, is the use of bisphosphonates. However, one of their main adverse side-effects is bisphosphonate-induced nephrotoxicity. The mechanism by which the latter occurs is not well-understood, although emerging evidence suggests that the effect of bisphosphonates on the kidney may differ between agents.


METHODS
The aim of this evaluation was to compare the renal toxicity of 6 mg ibandronate i.v. versus 4 mg zoledronic acid i.v. over a period of six months in women with breast cancer and bone metastases. A prospective randomized trial was carried out to examine specific kidney and other parameters (α1- and β2-microglobulin, albumin, α2-macroglobulin, IgG and C-reactive protein (CRP) generated from spontaneous urine samples from 17 patients of each group.


RESULTS
We were unable to find any significant difference between the two treatment groups with regard to renal toxicity. All patients, independently of the applied bisphosphonate, experienced only temporary renal dysfunction without any evidence of irreversible damage in terms of acute nephrotoxicity during the study period. α1-Microglobulin, a marker for proximal tubular damage, in particular, was not differently elevated in either group.


CONCLUSIONS
Both applied bisphosphonates were found to be well-tolerated and safe with regard to renal toxicity during a six-month treatment period in patients with otherwise healthy kidneys having advanced breast cancer and bone metastases.
Department of Obstetrics and Gynaecology, University Hospital Oldenburg, Oldenburg, Germany Department of Obstetrics and Gynaecology, University Hospital of Schleswig-Holstein, Luebeck, Germany doerte.luedders@gmx.de.
Dörte W
DW
Luedders
Department of Internal Medicine, University Hospital of Schleswig-Holstein, Luebeck, Germany.
Jürgen
J
Steinhoff
Department of Gynaecology and Obstetrics, Agaplesion Markus Hospital, Frankfurt (Main), Germany.
Marc
M
Thill
Department of Obstetrics and Gynaecology, University Hospital of Schleswig-Holstein, Luebeck, Germany.
Achim
A
Rody
Department of Obstetrics and Gynaecology, University Hospital of Schleswig-Holstein, Luebeck, Germany.
Michael K
MK
Bohlmann
D000208:Acute Disease; D000328:Adult; D000368:Aged; D050071:Bone Density Conservation Agents / Q000009:adverse effects*; D001859:Bone Neoplasms / Q000556:secondary*; D001943:Breast Neoplasms / Q000473:pathology*; D004164:Diphosphonates / Q000009:adverse effects*; D005260:Female; D006801:Humans; D000077557:Ibandronic Acid; D007093:Imidazoles / Q000009:adverse effects*; D007275:Injections, Intravenous; D007668:Kidney / Q000187:drug effects*; D008875:Middle Aged; D011446:Prospective Studies; D000077211:Zoledronic Acid
D050071:Bone Density Conservation Agents; D004164:Diphosphonates; D007093:Imidazoles; D000077211:Zoledronic Acid; D000077557:Ibandronic Acid
Nephrotoxicity; breast cancer; ibandronate; metastases; zoledronic acid