Azeez Farooki

Osteonecrosis of the maxilla and mandible in patients with advanced cancer treated with bisphosphonate therapy

Cases of osteonecrosis of the jaw (ONJ) have been reported with an increasing frequency over the past 5 years. ONJ is most often identified in patients with cancer who are receiving intravenous bisphosphonate (IVBP) therapy, but it has also been diagnosed in patients receiving oral bisphosphonates for nonmalignant conditions. To further categorize risk factors associated with ONJ and potential clinical outcomes of this condition, we performed a retrospective study of patients with metastatic bone disease treated with intravenous bisphosphonates who have been evaluated by the Memorial Sloan-Kettering Cancer Center Dental Service between January 1, 1996 and January 31, 2006. We identified 310 patients who met these criteria. Twenty-eight patients were identified as having ONJ at presentation to the Dental Service and an additional 7 patients were subsequently diagnosed with ONJ. Statistically significant factors associated with increased likelihood of ONJ included type of cancer, duration of bisphosphonate therapy, sequential IVBP treatment with pamidronate followed by zoledronic acid, comorbid osteoarthritis or rheumatoid arthritis, and benign hematologic conditions. Our data do not support corticosteroid use or oral health as a predictor of risk for ONJ. Clinical outcomes of patients with ONJ were variable with 11 patients demonstrating improvement or healing with conservative management. Our ONJ experience is presented here.

Management of Metabolic Effects Associated With Anticancer Agents Targeting the PI3K-Akt-mTOR Pathway

Agents inhibiting the phosphoinositide 3-kinase-Akt-mammalian target of rapamycin (PAM) pathway are currently in various stages of clinical development in oncology, ranging from some in early-phase evaluations to others that have already received regulatory approval for treatment in advanced cancers. The administration of PAM pathway inhibitors has been associated with metabolic toxicities of hyperlipidemia and hyperglycemia. The PAM Task Force of the National Cancer Institute Investigational Drug Steering Committee convened an interdisciplinary expert panel to review the pathophysiology of hyperlipidemia and hyperglycemia induced by PAM pathway inhibitors, summarize the incidence of these metabolic toxicities induced by such agents in the current literature, advise on clinical trial screening and monitoring criteria, and provide management guidance and therapeutic goals on occurrence of these toxicities. The overarching aim of this consensus report is to raise awareness of these metabolic adverse events to enable their early recognition, regular monitoring, and timely intervention in clinical trials. Hyperglycemia and hyperlipidemia are generally not acutely toxic and most often reversible with therapeutic intervention. Dose modifications or discontinuation of PAM pathway inhibitors should only be considered in situations of severe events or if progressive metabolic derangement persists after therapeutic interventions have been attempted for a sufficient duration. Specialty consultation should be sought to aid clinical trial planning and the management of these metabolic adverse events.

Atypical subtrochanteric femoral fractures in patients with skeletal malignant involvement treated with intravenous bisphosphonates.

BACKGROUND Atypical subtrochanteric femoral fractures have been identified as a potential complication of long-term bisphosphonate therapy for the treatment of osteoporosis. Patients with skeletal malignant involvement, who receive much higher cumulative doses of bisphosphonates than do patients with osteoporosis, may be at higher risk for the development of these fractures. METHODS A retrospective review of the imaging studies and case notes was done for patients with skeletal malignant involvement who received a minimum of twenty-four doses of intravenous bisphosphonates between 2004 and 2007 and were followed until death or the time of the latest review. Patients were classified as having an atypical subtrochanteric femoral fracture if they had a transverse subtrochanteric fracture following low-energy trauma or an impending fracture, together with radiographic findings of diffuse diaphyseal cortical thickening and cortical beaking at the subtrochanteric area. RESULTS In the study cohort of 327 patients, we identified four patients who developed an atypical subtrochanteric femoral fracture. All four patients were female, three had breast cancer, and one had myeloma. There was no significant difference between patients who developed an atypical subtrochanteric femoral fracture and those who did not with regard to the doses of intravenous bisphosphonates or the duration of treatment. CONCLUSIONS The prevalence of atypical subtrochanteric femoral fractures in patients with skeletal malignant involvement who are managed with high doses of intravenous bisphosphonates is low. All patients in our study who had development of these fractures had prodromal symptoms of thigh pain.

Skeletal-Related Events due to Bone Metastases from Differentiated Thyroid Cancer

BACKGROUND In oncology, the clinical impact of metastatic bone disease is conveyed via a composite end point termed skeletal-related events (SRE), which encompasses spinal cord compression, pathological fracture, a need for external beam radiation or surgery to bone, and hypercalcemia of malignancy. An appreciation for the high incidence of SRE in other advanced cancers involving the bone has led to the approval of potent antiresorptive agents because they delay the time to the first SRE and decrease the incidence of SRE. The risk and rate of SRE after diagnosis of bone metastasis have not been described in thyroid cancer; antiresorptive agents are not routinely used. METHODS This was a retrospective review of 245 differentiated thyroid cancer patients with bone metastases identified as part of routine clinical care at Memorial Sloan-Kettering Cancer Center between 1960 and 2011. The occurrence of SRE was recorded from the initial diagnosis of bone metastasis until final follow-up or death. RESULTS Seventy-eight percent of patients (192 of 245) either presented with or developed at least one SRE after the diagnosis of metastatic bone disease. The median time from identification of bone metastasis to first SRE was 5 months (excluding the 97 patients in whom first SRE occurred at the time of the bone metastasis diagnosis). Of the patients who sustained an initial SRE, 65% (120 of 192) went on to sustain a second SRE at a median of 10.7 months after the first event. SRE were frequently multiple; 39% (74 of 192) sustained three or more discrete SRE. CONCLUSION Thyroid cancer bone metastases identified as part of routine clinical follow-up frequently cause significant and recurrent morbidity. The incidence of SRE and median time to first SRE in metastatic thyroid cancer to bone are similar to those reported in other solid tumors. Prospective clinical trials to assess the efficacy of antiresorptive agents in this population are needed.

Effects of tyrosine kinase inhibition on bone metabolism: untargeted consequences of targeted therapies

Tyrosine kinase inhibitors (TKIs) are at the forefront of molecular-targeted therapies for cancer. With the advent of imatinib for the treatment of chronic myelogenous leukemia, a new wave of small-molecule therapeutics redefined the oncologic treatment to become chronically administered medications with tolerable side-effect profiles compared with cytotoxic agents. Effects on bone mineral metabolism were observed during early imatinib treatment, in the form of hypophosphatemia with increased urinary phosphorus excretion. This finding led to detailed investigations of off-target effects responsible for changes in bone cell maturation, activity, and impact on bone mass. Subsequently, another BCR-Abl inhibitor (dasatinib), vascular endothelial growth factor (VEGF) inhibitors (sorafenib and sunitinib) as well as rearranged during transfection (RET) inhibitors (vandetanib and cabozantinib) were developed. Inhibition of bone resorption appears to be a class effect and is likely contributed by TKI effects on the hematopoietic and mesenchymal stem cells. As long-term, prospective, clinical outcomes data accumulate on these targeted therapies, the full extent of off-target side effects on bone health will need to be considered along with the significant benefits of tyrosine kinase inhibition in oncologic treatment.

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.

Biochemical markers of bone turnover in osteonecrosis of the jaw in patients with osteoporosis and advanced cancer involving the bone

Osteonecrosis of the jaw (ONJ) has been hypothesized to result in part from a relative “oversuppression” of normal physiologic bone remodeling at the jaw brought about by bisphosphonate therapy. Biochemical markers of bone turnover give readily measurable information on integrated systemic bone remodeling activity, as measured by blood and urine assays. The intra‐ and interassay variability of most currently available assays is less than 10%, although many biological factors can influence levels of bone turnover markers. Bone turnover markers may show a dynamic response to changes in clinical status for a given disease state. Elevated bone turnover on and off treatment appears to predict adverse clinical consequences in both osteoporosis and cancer. Bisphosphonates effectively decrease the level of the bone turnover markers with a pattern depending on the marker, the bisphosphonate, the dose regimen, and the disease. However, long‐term (10‐year) treatment with bisphosphonates for osteoporosis does not appear to result in a progressive decline in bone turnover, as measured by markers and bone histology. The effects of long‐term (greater than 2 years) treatment with monthly intravenous bisphosphonates on bone turnover markers in cancer are unknown. Discontinuation of bisphosphonate therapy appears to allow a recovery of bone turnover, which is related to the bisphosphonate, the duration of therapy, and the disease being treated. At this time, data are limited with regard to the utility of bone turnover markers in assessing risk for ONJ and whether bone marker‐directed bisphosphonate holidays would be useful in prevention or treatment of ONJ.

Effect of long term imatinib on bone in adults with chronic myelogenous leukemia and gastrointestinal stromal tumors

Patients with chronic myelogenous leukemia (CML) or gastrointestinal stromal tumors (GIST) who take imatinib have abnormalities of bone metabolism. However, it is unclear what impact these changes have on bone mineral density (BMD). We prospectively analayzed levels of osteocalcin, a marker of bone formation secreted by osteoblasts, and serum N-telopeptide of type I collagen (NTX), a marker of bone resorption, as well as other minerals involved in bone metabolism in 19 patients with either CML or GIST We correlated these results with changes in bone mineral density as measured by serial dual energy X-ray absorptiometry (DEXA) scans over a two year period. Osteocalcin levels were low in 95% of patients and 37% had no measurable amount. Levels of NTX were less consistent. Nine patients (47%) had a decrease in BMD, four patients (2%) had an increase in BMD, and six patients (32%) had no change. There was no correlation between metabolic markers and change in BMD. We suggest that ongoing management of patients who take imatinib should include monitoring of bone health on a long term basis.

Bone effects of canagliflozin, a sodium glucose co-transporter 2 inhibitor, in patients with type 2 diabetes mellitus

ABSTRACT Canagliflozin, a sodium glucose co-transporter 2 (SGLT2) inhibitor approved for the treatment of type 2 diabetes mellitus (T2DM), lowers blood glucose by inhibiting renal glucose reabsorption and increasing urinary glucose excretion. It has been reported that SGLT2 inhibitors may have potential adverse effects on bone, including increased fracture risk and decreased bone mineral density (BMD). Across clinical studies, canagliflozin was not associated with meaningful changes in serum or urine calcium, vitamin D, or parathyroid hormone. Minimal increases in serum phosphate and magnesium that were within normal limits were seen with canagliflozin versus placebo. Canagliflozin was associated with increases in serum collagen type 1 beta-carboxy telopeptide (beta-CTX), a bone resorption marker, and osteocalcin, a bone formation marker. Decreases in total hip BMD were seen with canagliflozin 100 and 300 mg versus placebo after 2 years (–1.7%, –2.1%, –0.8%; differences of –0.9% and –1.2%), but not at other skeletal sites (normal age-related bone loss, ~0.5-1.0%/year). Changes in beta-CTX and total hip BMD were significantly associated with weight loss, which is known to increase bone resorption markers and decrease BMD. Canagliflozin was associated with a higher fracture incidence in an interim analysis of the CANagliflozin cardioVascular Assessment Study (CANVAS) in patients with a history or high risk of cardiovascular disease (incidence per 100 patient-years of 1.6, 1.6, and 1.1 with canagliflozin 100 and 300 mg and placebo), but not in other clinical studies of patients with T2DM. Fractures tended to occur as early as 12 weeks after initiating treatment and were primarily located in the distal parts of the upper and lower extremities. The reason for increased fracture risk with canagliflozin treatment is unknown, but is likely not related to a direct effect of canagliflozin on bone-related biomarkers. Data from ongoing canagliflozin studies, including CANVAS, will provide additional information on fracture risk in patients with T2DM.

Serum N-Telopeptide and Bone-Specific Alkaline Phosphatase Levels in Patients With Osteonecrosis of the Jaw Receiving Bisphosphonates for Bone Metastases

PURPOSE Oversuppression of bone turnover can be a critical factor in the pathogenesis of osteonecrosis of the jaw (ONJ). We investigated N-telopeptide of type I collagen (NTX) and bone-specific alkaline phosphatase (BAP) as potential predictors of ONJ onset. PATIENTS AND METHODS Patients with ONJ and available stored serum were identified retrospectively from the institutional databases. Four approximate points were examined: point of ONJ diagnosis and 12, 6, and 1 month before the diagnosis. NTX and BAP were measured using enzyme-linked immunosorbent assays and examined as possible predictors of ONJ. RESULTS From March 1998 to September 2009, we identified 122 patients with ONJ. Of these, 56 (46%) had one or more serum samples available. Overall, 55 patients (98%) received bisphosphonates. Using the exact dates, no obvious patterns in either NTX or BAP were noted. Similarly, using the ordinal points, no evidence of suppression of NTX or BAP over time was seen. The consecutive median values were as follows: The median NTX values were 8.0 nmol/L (range 3.8 to 32.9) at 12 months before ONJ; 9.5 nmol/L (range 4.7 to 42.7) at 6 months; 9.5 nmol/L (range 4.5 to 24.6) at 1 month, and 10.4 nmol/L (range 4.4 to 32.5) at the ONJ diagnosis. The median BAP values were BAP 18.0 U/L (range 7.0 to 74) at 12 months before ONJ; 18.0 U/L (range 4.0 to 134) at 6 months; 14.0 U/L (range 4.0 to 132) at 1 month, and 18.0 U/L (range 0.7 to 375) at the ONJ diagnosis. Only 2 patients (4%) had NTX and 17 (30%) had BAP below the normal range at the ONJ diagnosis. CONCLUSIONS In the present large retrospective study, no trends were seen in the NTX and BAP levels before the ONJ diagnosis.