Octreotide Is Ineffective in Treating Tumor-Induced Osteomalacia: Results of a Short-Term Therapy

Abstract

Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome in which unregulated hypersecretion of fibroblast growth factor 23 (FGF23) by phosphaturic mesenchymal tumors (PMT) causes renal phosphate wasting, hypophosphatemia, and osteomalacia. The resulting mineral homeostasis abnormalities and skeletal manifestations can be reversed with surgical resection of the tumor. Unfortunately, PMTs are often difficult to locate, and medical treatment with oral phosphate and vitamin D analogues is either insufficient to manage the disease or not tolerated. Octreotide has been proposed as a potential treatment for TIO due to the presence of somatostatin receptors (SSTR) on PMTs; however, the role of somatostatin signaling in PMTs and the efficacy of treatment of TIOs with somatostatin analogues is not clear. In an effort to evaluate the efficacy of octreotide therapy in TIO, five subjects with TIO were treated with octreotide for 3 days. Blood intact FGF23, phosphate, and 1,25(OH) D , and tubular reabsorption of phosphate (TRP) were measured at frequent time points during treatment. Octreotide's effects were assessed by comparing group means of the biochemical parameters at each time-point to mean baseline values. There were no significant changes in blood phosphate, FGF23, 1,25(OH) D , or TRP during octreotide treatment, consistent with a lack of efficacy of octreotide in treating TIO. © 2017 American Society for Bone and Mineral Research.

Tumor-induced osteomalacia: experience from three tertiary care centers in India

“…Since SUV max is a surrogate marker of SSTR expression (42), it may be inferred that signal transduction via somatostatin receptors is possibly not involved in the regulation of FGF23 secretion by the tumor tissue. As firm evidence to our hypothesis is the fact that octreotide, a somatostatin receptor ligand, is largely ineffective in correcting the biochemical abnormalities in TIO (43, 44, 45).…”

Tumor induced osteomalacia in head and neck region: single center experience and systematic review

“…Seufert et al reported a patient with left thigh TIO localized on octreotide scinitigraphy having complete resolution of phosphaturia and normalization of serum phosphorus with 50–100 µg of octreotide thrice a day in preoperative setting (125). However, this initial success has not been replicated in subsequent studies (34, 126). Extrapolating from patients with hypoparathyroidism with elevated FGF-23 and serum phosphorus levels, Gellers et al advocated for the use of cinacalcet in the treatment of TIO (127).…”

Tumor-induced osteomalacia: a case report

“…The basic regimen for TIO includes phosphate and active vitamin D (calcitriol and alfacalcidol) supplements [ 30 ] Side effects include nephrolithiasis, nephrocalcinosis, impaired renal function, and either secondary or tertiary hyperparathyroidism [ 29 ], necessitating close surveillance. Somatostatin receptor analogues have been used with some success [ 29 , 31 – 33 ]. Inconsistent results are reported regarding the efficacy of somatostatin receptor-based therapy with octreotide in this setting [ 31 – 33 ].…”