Osteonecrosis of the jaw associated with bisphosphonate therapy: tips for the practicing oncologist

Molecular profiling of oral microbiota in jawbone samples of bisphosphonate-related osteonecrosis of the jaw

Oral Diseases (2012) 18, 602–612

Objective:  Infection has been hypothesized as a contributing factor to bisphosphonate (BP)‐related osteonecrosis of the jaw (BRONJ). The objective of this study was to determine the bacterial colonization of jawbone and identify the bacterial phylotypes associated with BRONJ.

Materials and methods:  Culture‐independent 16S rRNA gene‐based molecular techniques were used to determine and compare the total bacterial diversity in bone samples collected from 12 patients with cancer (six, BRONJ with history of BP; six, controls without BRONJ, no history of BP but have infection).

Results:  Denaturing gradient gel electrophoresis profile and Dice coefficient displayed a statistically significant clustering of profiles, indicating different bacterial population in BRONJ subjects and control. The top three genera ranked among the BRONJ group were Streptococcus (29%), Eubacterium (9%), and Pseudoramibacter (8%), while in the control group were Parvimonas (17%), Streptococcus (15%), and Fusobacterium (15%). H&E sections of BRONJ bone revealed layers of bacteria along the surfaces and often are packed into the scalloped edges of the bone.

Conclusion:  This study using limited sample size indicated that the jawbone associated with BRONJ was heavily colonized by specific oral bacteria and there were apparent differences between the microbiota of BRONJ and controls.

Cancer treatment-induced bone loss: pathophysiology and clinical perspectives

Hormone-ablative therapies for breast or prostate cancer can cause marked and rapid reductions in circulating estrogen or testosterone levels, resulting in significant effects on bone metabolism and cancer treatment-induced bone loss (CTIBL). Most patients with cancer are over the age of 65 and are already at risk for osteoporosis. Thus, accelerated bone loss from CTIBL is especially concerning in this population. Although there are currently no approved therapies for the treatment or prevention of CTIBL, oral bisphosphonates have been used in settings other than oncology to treat bone loss. New-generation i.v. bisphosphonates have demonstrated promising activity in preventing CTIBL in patients receiving hormonal therapy for breast or prostate cancer. In particular, zoledronic acid not only prevents CTIBL in both breast and prostate cancer patients but also increases bone mineral density above baseline. Such agents have the potential to delay or prevent CTIBL in patients receiving hormonal therapies.

Fosaprepitant (MK-0517): a neurokinin-1 receptor antagonist for the prevention of chemotherapy-induced nausea and vomiting

Chemotherapy-induced nausea and vomiting (CINV) is a distressing and common adverse event associated with cancer treatment. Updated anti-emetic guidelines were published in 2007 by the National Comprehensive Cancer Network and in 2006 by the American Society of Clinical Oncology, which have included the use of the new and more effective anti-emetic agents (5-hydroxytryptamine-3 [5-HT(3)] receptor antagonists and neurokinin-1 [NK-1] receptor antagonists). Aprepitant is a selective NK-1 receptor antagonist approved as part of combination therapy with a corticosteroid and a 5-HT(3) receptor antagonist for the prevention of acute and delayed CINV. Fosaprepitant (also known as MK-0517 and L-758,298) is a water-soluble phosphoryl prodrug for aprepitant, which, when administered intravenously, is converted to aprepitant within 30 min after intravenous administration via the action of ubiquitous phosphatases. Because fosaprepitant is rapidly converted to the active form (aprepitant), it is expected to provide the same aprepitant exposure in terms of AUC, and a correspondingly similar anti-emetic effect. Clinical studies have suggested that fosaprepitant could be appropriate as an intravenous alternative to the aprepitant oral capsule. In a study in healthy subjects, fosaprepitant was well tolerated up to 150 mg (1 mg/ml), and fosaprepitant 115 mg was bioequivalent in its AUC to aprepitant 125 mg. Fosaprepitant 115 mg has been submitted for FDA approval as an alternative on day 1 of a 3-day oral aprepitant regimen, with oral aprepitant administered on days 2 and 3. Fosaprepitant may be a useful parenteral alternative to oral aprepitant. Further study is needed to clarify the use of fosaprepitant for the prevention of CINV, and to clarify optimal dosing regimens that may be appropriate substitutes for oral aprepitant.