Biochemical prediction of response of bone metastases to treatment

Abstract

Summary Assessment of response of skeletal metastases to systemic therapy is currently dependent on radiological evidence of bone healing. We have performed a prospective study of additional response criteria in patients with progressive bone metastases from breast cancer. Changes in these potential markers of response were correlated with the radiological response and the time to treatment failure (TTF).Successful systemic therapy typically led to a transient increase in osteoblast activity ('flare'), a reduction in osteoclast activity and symptomatic improvement. After 1 month a > 10% rise in serum osteocalcin (BGP) Osteoblast activity was monitored by serial measurements of alkaline phosphatase bone isoenzyme (ALP-BI) and osteocalcin (BGP). Serum calcium, tartrate resistant acid phosphatase (TRP) and urinary excretion of calcium and hydroxyproline were measured to assess osteoclast activity. Serum for measurement of BGP, ALP-BI and TRP was obtained from a morning blood sample following centrifugation. The aliquot for TRP was acidified with 20 p1 of 5 M acetate buffer (pH 5) per ml of serum. All samples were frozen within 6 h and stored at -20°C. A morning spot urine sample was collected for measurement of calcium and hydroxyproline excretion after an overnight fast and stored at -20°C. Foods rich in collagen were avoided for 18 h prior to urine collection for hydroxyproline. Following pretreatment estimations measurements of serum calcium, BGP, and urinary calcium excretion were performed monthly, ALP-BI at 1, 3 and 6 months during treatment and TRP and urinary hydroxyproline excretion 3 monthly.Bone scans, with plain radiographs of abnormal areas, were performed before treatment and repeated three monthly. Standard overlapping views were taken 3-4h after injection of 500 megabecquerels of technetium99m labelled methylene diphosphonate (MDP). Symptomatic response was assessed by a questionnaire completed by the patient. Severity of pain and mobility were rated by the patient and combined with a scoring of analgesic consumption and the UICC performance status to produce an overall symptom score which was expressed as a percentage of the maximum possible score. (Details of pain and activity questionnaire available from the authors on request).ALP-BI was measured by the modified heat-inactivation technique described by Moss & Whitby (1975). This method utilises the different heat stability characteristics of the bone and liver isoenzymes. The total enzyme activity is measured and the presence of significant amounts of ALP from other sources (e.g. gut) excluded by electrophoresis. Serum is incubated at 56°C and at this temperature more than 99% of the bone isoenzyme decays within 15 min. The residual activity of the sample is measured after 15 and 25 min incubation and reflects the inactivation rate of the liver component. The total liver component can be determined by extrapolation from these two measurement and ALP-BI Br.

Measurement of urinary collagen cross-links indicate response to therapy in patients with breast cancer and bone metastases

“…Urinary cAMP was elevated in the absence of raised PTHrP, and this may reflect the actions of an as yet unidentified tumour product that affects the kidney. In contrast to previous authors (Coleman et al, 1988;Dodwell et al, 1990) we were unable to demonstrate a significant increase in urinary calcium excretion in patients with progressive bone disease. Urinary calcium excretion does not change in the presence of sclerotic bone metastases, whereas urinary cross-link excretion was shown to be elevated (Sano et al, 1994).…”

Preliminary results of the use of urinary excretion of pyridinium crosslinks for monitoring metastatic bone disease

“…The urinary excretion of these compounds, expressed as a ratio to urinary creatinine, has been measured using ion-pair reversed phase high-performance liquid chromatography in 20 patients receiving oral pamidronate for bone metastases from breast cancer.Before treatment the ratio of pyridinoline and deoxypyridinoline to creatinine in urine (UPCR and UdPCR respectively) were each above normal in 16/20 (80%) (Hortobagyi et al, 1984;Coleman et al, 1988a). These have included urinary calcium (Campbell et al, 1983) and hydroxyproline excretion (Blomqvist et al, 1987) which are influenced by the rate of bone resorption.…”

“…Several biochemical markers of bone metabolism have been studied as indicators of bone response (Hortobagyi et al, 1984;Coleman et al, 1988a). These have included urinary calcium (Campbell et al, 1983) and hydroxyproline excretion (Blomqvist et al, 1987) which are influenced by the rate of bone resorption.…”

Parathyroid hormone-related protein secretion is inhibited by oestradiol and stimulated by antioestrogens in KPL-3C human breast cancer cells

“…Up-regulation of PTHrP secretion by antioestrogens reminds us that antioestrogens sometimes cause a flare phenomenon in patients with advanced breast cancer (Plotkin et al, 1978;Coleman et al, 1988). This unresolved phenomenon might be explained by these data, i.e.…”