Targeted etanercept for treatment-refractory pain due to bone metastasis: two case reports

Parallel bodies of research suggest both a central role for osteoclasts in tumor-induced destruction of bone and the ability of biologic tumor necrosis factor-alpha (TNF-alpha) antagonists to attenuate the osteoclast-mediated bone destruction that accompanies a variety of nonmalignant disorders. Additional studies have implicated TNF-alpha in the promotion of osteoclast-mediated malignant osteolysis and the pathogenesis of neuropathic pain. TNF-alpha antagonists have the potential to interfere in both processes.

This article reviews the cases of 2 patients with treatment-refractory pain due to cancer metastases to bone who were given targeted injections of the biologic anti-TNF agent etanercept based on its potential to interfere directly with both malignant activation of osteoclasts and neuropathic pain.

One patient had a diagnosis of non-small cell lung cancer and the other had a diagnosis of breast cancer. Both presented with treatment-refractory pain due to bone metastases. The 2 patients received etanercept 25 mg by targeted SC injection in anatomic proximity to the site of spinal metastasis for relief of their treatment-refractory pain.

Both patients experienced rapid, substantial, and sustained relief of chronic refractory pain at the treatment site after targeted administration of etanercept. Symptomatic improvement was correlated with objective measures of improvement, including weight gain in 1 patient and decreased uptake of radioactive tracer at the targeted site on positron emission tomography in the other.

Etanercept delivered by targeted SC injection may be of clinical benefit in selected patients with treatment-refractory pain caused by bone metastases. Clinical trials are needed to define the potential benefit of biologic TNF-alpha antagonists in the treatment and prevention of malignant osteolysis.