Emerging drugs for the management of cancer treatment induced bone loss.

AREAS COVERED IN THIS REVIEW: We focus our attention on data on the efficacy of currently available and emerging drugs for the management of cancer treatment induced bone loss (CTIBL) found in a PubMed research from 1997 till today. IMPORTANCE OF THE FIELD: One of the most common and severe safety issues of the antihormonal therapy in both sexes is the CTIBL and the related fragility fractures. In postmenopausal women with estrogenic receptor positive breast cancer, the third-generation aromatase inhibitors (AIs) are the standard therapy. Observational retrospective studies have found that AIs treated patients had a high rate of bone loss and fracture risk (RR 1.3). Also in men with prostate cancer receiving androgen deprivation therapy, the increase in bone turnover and the consequent bone loss are very rapid and sustained significantly increasing the fracture risk. WHAT THE READER WILL GAIN: The aim of our review is to provide the current evidences for the management of bone loss and fracture risk in this subpopulation. TAKE HOME MESSAGE: The very high rate of bone loss and the high incidence of fractures indicate that cancer patients at risk of CTIBL need to be carefully monitored and stratified for fracture risk. Although there is a strong evidence of efficacy in prevention of bone loss and reduction of fracture risk for many drugs approved for postmenopausal osteoporosis (PMO) and male osteoporosis, for CTIBL there are actually no drugs approved for this indication.

Serum 25-hydroxyvitamin D levels modulate the acute-phase response associated with the first nitrogen-containing bisphosphonate infusion.

The acute-phase response (APR) is the most frequent side effect after the first dose of intravenous nitrogen-containing bisphosphonates (N-BPs). It has been demonstrated in vitro that N-BPs stimulate gammadelta T-cell proliferation and production of cytokines and that vitamin D is able to modulate them. Therefore, we have studied the relationship between bone metabolism parameters, particularly for 25-hydroxyvitamin D [25(OH)D], and APR in patients treated with 5 mg zoledronic acid intravenously. Ninety N-BP-naive osteoporotic women (63.7 +/- 10.6 years of age) were stratified for the occurrence of APR (APR(+)) or not (APR(-)) and quantified by body temperature and C-reactive protein (CRP). The APR(+) women had significantly lower 25(OH)D levels than the APR(-) women. Levels of 25(OH)D were normal (>30 ng/mL) in 31% of APR(+) women and in 76% of APR(-) women. The odds ratio (OR) to have APR in 25(OH)D-depleted women was 5.8 [95% confidence interval (CI) 5.30-6.29; p < .0002] unadjusted and 2.38 (95% CI 1.85-2.81; p < .028) after multiple adjustments (for age, body mass index, CRP, calcium, parathyroid hormone, and C-telopeptide of type I collagen). Levels of 25(OH)D were negatively correlated with postdose body temperature (r = -0.64, p < .0001) and CRP (r = -0.79, p < .001). An exponential increase in fever and CRP has been found with 25(OH)D levels lower than 30 ng/mL and body temperature less than 37 degrees C, whereas normal CRP was associated with 25(OH)D levels above 40 ng/mL. The association between post-N-BPs APR and 25(OH)D suggests an interesting interplay among N-BPs, 25(OH)D, and the immune system, but a causal role of 25(OH)D in APR has to be proven by a randomized, controlled trial. However, if confirmed, it should have some practical implications in preventing APR.

The effect of bisphosphonates on gene expression: GAPDH as a housekeeping or a new target gene?

BACKGROUND: RT-PCR has been widely used for the analysis of gene expression in many systems, including tumor samples. GAPDH (Glyceraldehyde-3-phosphate dehydrogenase) has been frequently considered as a constitutive housekeeping gene and used to normalize changes in specific gene expression. However, GAPDH has been shown to be up-regulated in many cancers and down-regulated by chemotherapic drugs. Bisphosphonates, potent inhibitors of bone resorption, have recently shown a direct and indirect antitumor effect in vitro and in animal models. They exert their effects mainly by inhibiting the mevalonate pathway but also by modulating the expression of many genes not only in osteoclasts but also in cancer cells. METHODS: We evaluated GAPDH gene expression by real time RT PCR in breast (MCF-7 and T47D) and prostate (PC3 and DU-145) cancer cell lines treated with amino and non-amino bisphosphonates. RESULTS: Our results showed that amino-bisphosphonates significantly decrease in a dose-dependent manner the expression of GAPDH gene. CONCLUSION: Therefore, GAPDH is inaccurate to normalize mRNA levels in studies investigating the effect of bisphosphonates on gene expression and it should be avoided. On the other hand, this gene could be considered a potential target to observe the effects of bisphosphonates on cancer cells.