Treatment of tumour-induced hypercalcaemia with the bisphosphonate pamidronate: dose-response relationship and influence of tumour type

BACKGROUND

Patients with humoral hypercalcaemia of malignancy appear to respond less well to biphosphonate therapy than hypercalcaemic patients with osteolytic metastases. On the other hand, pamidronate is currently the most potent of the commercially available biphosphonates and it is recommended that its dose be increased as a function of pretreatment calcium levels.

PATIENTS AND METHODS

We reviewed our experience with pamidronate in 160 patients with tumour-induced hypercalcemia (TIH) persisting after rehydration, particularly the influence of the dose administered, the tumour type and the presence of bone metastatic involvement on the calcaemic and calciuric response to pamidronate therapy.

RESULTS

Serum Ca was normalized in 92% of the cases (87% when Ca was corrected for protein levels). After therapy, 59% of the patients developed asymptomatic hypocalcaemia (30% for Corr. Ca levels). A multiparameter regression analysis revealed that the response to pamidronate was significantly (P < 0.01) influenced by initial Ca levels up to days 5-7 and, thereafter, only by the dose received. To confirm the dose effect, we divided the patients into three groups according to the median dose received, namely 0.5 mg/kg (n = 35), 1.0 mg/kg (n = 52), and 1.5 mg/kg (n = 73). The differences among the three groups became significant (P < 0.05) from days 5-7 until the end of the evaluation (days 22-26). Similarly, the success rate, considering Corr. Ca levels, was 80% for the 0.5 and 1.0 mg/kg groups combined, compared to 94% for the 1.5 mg/kg group (P < 0.05). The duration of normocalcaemia was similarly more prolonged in the high-dose group. There was a dose-response relationship only in patients with Ca levels above 3.0 mmol/L and in patients with an elevated index of tubular calcium reabsorption. By contrast, the decrease in Ca levels and in fasting urinary calcium excretion, a sensitive index of bone resorption, were not significantly influenced by the primary tumour site or by the presence of bone metastatic involvement.

CONCLUSIONS

Our data demonstrate a dose-response relationship for pamidronate in TIH over an efficient hypocalcaemic dose range, at least in patients with an elevated tubular calcium reabsorption, which helps to resolve conflicting data in the literature. We suggest that a dose of around 1.5 mg of pamidronate/kg is optimal for the treatment of TIH, except in patients with mild hypercalcaemia, for whom a dose of 1 mg/kg appears to be sufficient. At these dose levels, the efficacy of pamidronate is not significantly influenced by the tumour type or the degree of metastatic bone involvement.

Cyclical pamidronate infusions in postmenopausal osteoporosis

OBJECTIVES

Until recently, two bisphosphonates, pamidronate (APD) and etidronate were available for clinical purposes. Contrary to etidronate, pamidronate was not extensively studied in osteoporosis. Therefore, we investigated the effect of cyclic intravenous APD treatment in postmenopausal osteoporosis.

METHODS

Parameters of bone remodelling and lumbar spine bone mineral density (BMDL) were assessed in 36 postmenopausal women with osteoporosis (BMDL t-score < -2.5). They received five courses of APD. Intervals between courses were defined according to the fasting urinary calcium excretion (UCa/Cr, mg/mg creatinine) which was measured before each APD course and every 2 weeks after the first treatment. The patients were retreated when UCa/Cr had reached baseline levels. Serum biochemical parameters and urinary hydroxyproline (UOHPro/Cr, mg/mg) were measured before each APD.

RESULTS

UCa/Cr decreased during 21-28 days after each course but UCa/Cr measured before APD infusion remained unchanged. UOHPro/Cr significantly fell after the third APD (P = 0.02). Serum calcium was however not modified. Parameters of bone remodelling decreased with time: bone-GLA protein (BGP) started to fall after the first APD (P = 0.0001) and continued to decrease until the fourth APD course, alkaline phosphatase (ALP) significantly decreased after the first APD (P = 0.005); intact PTH significantly increased at the fifth APD (P = 0.02). BMDL significantly increased after 1 year treatment: +2.9% of baseline value.

CONCLUSIONS

Cyclical pamidronate treatment of postmenopausal osteoprosis appeared to be effective in reducing bone turnover assessed by BGP, ALP and OHPro/Cr. This effect is followed by an increase in vertebral BMD.

Efficacy and safety of the bisphosphonate tiludronate for the treatment of tumor-associated hypercalcemia

Tiludronate is a new bisphosphonate whose efficacy has already been reported for the prevention of postmenopausal bone loss. We have evaluated its efficacy and tolerance by a dose-finding study in 19 hypercalcemic cancer patients after adequate intravenous (iv) rehydration. Treatment consisted of 3 days of iv tiludronate given at doses of 3.0 mg/kg/day (n = 3), 4.5 mg/kg/day (n = 3), or 6.0 mg/kg/day (n = 13); this iv therapy was followed by 17 days of oral tiludronate, 400 mg (n = 13) or 800 mg (n = 6) daily. Treatment had to be discontinued in 9 patients, including 3 because of evident treatment failure and 1 because of severe toxicity. After iv tiludronate, 13/18 patients had a normal Ca level, including 10/12 who had received 6.0 mg/kg/day, but Ca2+ levels were fully normalized in only 4/18 and 3/12 patients, respectively. After 6.0 mg/kg/day, Ca levels had fallen from 12.1 +/- 0.3 to 10.0 +/- 0.4 mg/dl (P less than 0.0005), whereas fasting urinary calcium excretion went from 0.639 +/- 0.099 to 0.272 +/- 0.054 mg Ca/mg creatinine on d4 (P less than 0.001). On the other hand, oral tiludronate was unable to normalize Ca in patients who were still hypercalcemic after the iv course, although the daily administration of 800 mg appeared to be more efficient than the 400 mg daily dosage. The administration of tiludronate caused an increase in serum phosphate levels, from 2.9 +/- 0.2 to 3.7 +/- 0.2 mg/dl after the iv course, probably through an increase in the TmP/GFR index, which went from 2.3 +/- 0.2 to 3.6 +/- 0.4 mg/dl (P less than 0.05). Three patients had an increase in serum creatinine levels after the iv course, one obese patient developing an acute renal insufficiency; during oral tiludronate therapy, 5 other patients also presented an increase in serum creatinine levels. Oral tiludronate administration was also associated with occasional nausea and vomiting. In summary, compared with aminobisphosphonates, tiludronate is not indicated for the treatment of tumor-associated hypercalcemia because of the need for high iv doses which are potentially nephrotoxic.

Comparative evaluation of markers of bone resorption in patients with breast cancer-induced osteolysis before and after bisphosphonate therapy

The understanding of the pathophysiology and the monitoring of metastatic bone disease remains unsatisfactory. We compared several new markers of bone turnover in normocalcaemic patients with breast cancer-induced osteolysis before and after a single infusion of the bisphosphonate pamidronate. We studied 19 ambulatory patients with advanced breast cancer and extensive bone metastases who did not receive any systemic antineoplastic therapy. Pamidronate was administered at doses of 30, 60, 90 or 120 mg and the patients were followed weekly during a mean of 8 (range 4-10) weeks. Compared with healthy premenopausal women, the percentage of elevated values at baseline was 47% for fasting urinary calcium (uCa), 74% for hydroxyproline, 83% for CrossLaps (a new marker of type I collagen degradation) and 100% for the collagen cross-links (measured by high performance liquid chromatography), namely pyridinoline (Pyr) and deoxyPyr (D-Pyr). Pretreatment levels of uCa did not correlate significantly with any of the four markers of bone matrix resorption, whereas the correlations between these four markers were generally significant (r(s)=0.43-0.71). Alkaline phosphatase correlated significantly with markers of bone matrix resorption (r(s)=0.54-0.74). All parameters, except phosphaturia (uPi) and the bone formation markers (osteocalcin and alkaline phosphatase), fell significantly after pamidronate therapy, up to day 42 for hydroxyproline, D-Pyr and CrossLaps and day 56 for uCa. This longer lasting effect was probably due to the parathyroid hormone (PTH) surge following the decrease in serum calcium, implying that the decrease in uCa can overestimate the effects of bisphophonates on bone resorption. The decrease in bone turnover parameters was most marked for CrossLaps, indicating the potential of this new marker for monitoring therapy. Sequential determinations of markers of bone matrix resorption should be useful in delineating the optimal therapeutic schemes of bisphosphonates and for evaluating treatment effects on bone in cancer patients.

Decreased efficacy of bisphosphonates for recurrences of tumor-induced hypercalcemia

Bisphosphonates are now the standard treatment for tumor-induced hypercalcemia (TIH), and pamidronate can normalize serum Ca in at least 90% of the patients treated for the first time. However, there are few data on the treatment of TIH when it recurs, and published results are contradictory. We studied 29 patients with solid tumors, 14 of whom had breast cancer and all of whom were naive to bisphosphonate therapy. They were retreated with pamidronate (median dose 1 mg/kg for both courses) for recurrence of TIH after a median interval of 78 (range 7-297) days. Fourteen of them, 7 of whom had breast cancer, were treated a third time 28 (range 5-79) days after the second course (median dose of pamidronate 1.5 mg/kg). Baseline Ca levels were not significantly different before each course, but the nadirs after each treatment progressively increased, 9.3 +/- 0.2 mg/dl, 10.5 +/- 0.3 mg/dl, and 12.3 +/- 0.4 mg/dl after the 1st, 2nd and 3rd administrations, respectively (P<0.05). The percentage of treatment failures also progressively increased: 10%, 31% and 85% (P< 0.05). This decreased hypocalcemic effect was essentially observed in patients without bone metastases or with tumors other than breast cancer. Thus, in patients without bone metastases, Ca levels did not decrease at all after the 3rd course, whereas the responses were not significantly different between the three courses in patients with bone metastases. Baseline urinary hydroxyproline, a marker of bone resorption, increased progressively from course to course, especially in patients with bone metastases or breast cancer, but this was not the case for parameters of bone formation. There was also a progressive increase in PTHrP levels accompanied by an increase in the number of patients with enhanced kidney reabsorption of Ca and a decrease in the threshold for Pi excretion, which was significant in patients without bone metastases. In conclusion, pamidronate was progressively less efficient when hypercalcemia recurred. This was observed mainly in patients with hypercalcemia of humoral origin. Tumor progression is accompanied by an enhanced release of osteolytic factors, notably PTHrP, that increase bone resorption and enhance kidney calcium reabsorption, especially in patients without bone metastases. When both phenomena occur, the response to bisphosphonates becomes minimal and the usefulness of therapy questionable.

Limb-body wall complex: 4 new cases illustrating the importance of examining placenta and umbilical cord

Limb-body wall complex (LBWC) is a rare, sporadic, congenital defect defined as a combination of at least two of three characteristics: 1. limb defects, 2. anterior body wall defects, and 3. exencephaly or encephalocoele with/without facial clefts. Three pathogenic mechanisms have been proposed: early amnion rupture, vascular disruption and embryonic dysgenesis. In this study we carried out the pathological evaluation of four fetuses with LBWC and their placentas. None of the cases had craniofacial defects. Three fetuses showed an abdominal wall defect with eventration of abdominal organs, cloacal exstrophy, absent external genitalia, abnormal internal genitalia, scoliosis and lower limb defects. One fetus showed failure of closure of both thoracic and abdominal walls with ectopia cordis, evisceration of left lung and abdominal organs, severe reduction defect of left arm, but normal colon, anus, bladder, genitalia and lower limbs. All cases had a short, malformed umbilical cord, incompletely covered by amnion. The umbilical vessels were embedded in an amniotic sheet which connected the skin margin of the anterior body wall defect to the placenta. These anomalies suggest an abnormal body stalk development as a pathogenic mechanism for LBWC. Prenatally, the abnormal fetoplacental attachment can be detected ultrasonographically by the end of the first gestational trimester. Postnatally, the examination of placenta, umbilical cord and membranes is crucial in confirming the diagnosis of LBWC.

A severe case of mandibuloacral dysplasia in a girl

We report on a 16-year-old girl with mandibuloacral dysplasia, a rare progeroid syndrome. She presented at age 2 years with thin skin on the limbs, characteristic face with prominent eyes, a pinched nose, micrognathia, and small mouth. Hair was sparse and brittle. The terminal phalanges were hypoplastic and showed acroosteolysis. On follow-up, hands and feet showed progressive camptodactyly of fingers and toes with total loss of subcutaneous tissue. The clavicles were hypoplastic. Intelligence was normal. We review the literature on the subject and discuss differential diagnosis.

Application of fluorescence in situ hybridization for early prenatal diagnosis of partial trisomy 6p/monosomy 6q due to a familial pericentric inversion

We report the prenatal diagnosis of a karyotype 46,XY,rec(6)dup p, inv(6) (p23q27) mat detected by fluorescence in situ hybridization using chromosome 6pter and 6qter specific DNA markers. This partial duplication-deletion (6p12-->pter; 6q27-->qter) emanated from a balanced pericentric inversion 46,XX inv(6) (p23q27)pat present in the mother. The phenotypes of two relatives with the same unbalanced anomaly are described. This report illustrates the sensitivity and specificity of fluorescence in situ hybridization (FISH) and its benefit in rapid and unequivocal prenatal diagnosis of subtle chromosomal rearrangements.

Technical and clinical validation of a new immunoradiometric assay for human osteocalcin

The measurement of circulating osteocalcin or bone GLA protein (BGP) constitutes a well established and non-invasive means for evaluating preferentially the bone formation rate, but most available commercial assays suffer from several technical constraints, notably a rapid degradation of BGP at room temperature or after thawing and the inability to measure subnormal values. We evaluated, from a technical and a clinical viewpoint, a newly available two-site sandwich immunoradiometric assay (IRMA) using standard of human origin and two different monoclonal antibodies. The theoretical and functional assay detection limit was 0.3 ng/ml. Concentrations of BGP progressively decreased when the serum was left at 4 degrees C or at room temperature (mean apparent loss of 15% after 24 h). Two cycles of freezing-thawing only lightly reduced the BGP concentrations. The mean (+/- SD) BGP concentration was 19.6 +/- 7.9 ng/ml in healthy subjects (NI, N = 61); the normal range was 8.1-35.6 ng/ml. There was a marked difference between pre- and postmenopausal women: 15.1 +/- 4.4 vs 22.3 +/- 8.4 ng/ml, respectively (p < 0.05). The mean BGP concentration in patients with tumor-induced hypercalcemia (N = 29) was not significantly different from NI, but nine patients (31%) had subnormal levels and five (17%) had elevated BGP levels. Concentrations of BGP were significantly increased in patients with hyperparathyroidism (N = 14) (45.1 +/- 21.0 ng/ml) and significantly lower than NI in patients with hypoparathyroidism (N = 18) (7.3 +/- 4.6 ng/ml). Concentrations of BGP were also measured by a classical radioimmunoassay using bovine standards and tracer; the correlations between both sets of measurements were significant in all groups, except in patients with hypoparathyroidism. In summary, this newly available IRMA for measuring circulating human BGP appears to be quite sensitive, reproducible and robust. It should be especially useful for investigating clinical conditions characterized by a low bone formation rate.

Circulating PTHrP concentrations in tumor-induced hypercalcemia: influence on the response to bisphosphonate and changes after therapy

We studied the influence of circulating parathyroid hormone-related protein (PTHrP) concentrations on the response of hypercalcemic cancer patients to bisphosphonate therapy. We also examined the changes in circulating PTHrP levels during the normalization of serum Ca to determine if part of the increase in PTHrP concentrations is not secondary to hypercalcemia itself, as suggested by some in vitro data. We sequentially measured in 45 hypercalcemic cancer patients treated by pamidronate the circulating concentrations of PTHrP (by an amino-terminal RIA; normal values < 9 pmol/liter), Ca, Ca2+, Pi, intact PTH, and the fasting urinary excretion of Ca (Ca/Cr) and cyclic AMP (cAMP). Mean +/- SEM baseline PTHrP levels were 9.5 +/- 1.3, with a median (range) value of 6.0 (< 3.4-43) pmol/liter. PTHrP levels were elevated in 18 of 45 patients, more often in epidermoid than in glandular carcinomas (P < 0.05), and they were significantly (P < 0.05) correlated with the concentrations of Pi (r = -0.46), Ca/Cr (r = -0.31), and urinary cAMP (r = 0.47). Mean pretreatment Ca levels were not significantly different between patients with elevated and patients with normal PTHrP levels, 13.3 +/- 0.4 versus 12.9 +/- 0.4 mg/dl, but the concentrations became significantly different (P < 0.005) 4 days after therapy, 10.2 +/- 0.3 versus 9.2 +/- 0.1 mg/dl, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Incidence of low-fluorescence alpha satellite region on chromosome 21 escaping detection of aneuploidy at interphase by FISH

Aneuploidy detection for chromosome 21 by fluorescence in situ hybridization (FISH) to interphase nuclei using a probe specific for the alphoid DNA sequences D21Z1/D13Z1 should be avoided. An extreme heteromorphism, resulting in misdiagnosis if interphase FISH is the only test employed, may be far more frequent (4/101) than expected.

Nasal human calcitonin for tumor-induced hypercalcemia

We treated four hypercalcemic cancer patients by nasal hCT, 3 x 2 mg daily, which has been reported to be active in Paget's disease at lower doses. Only one patient became normocalcemic and mean (+/- SEM) calcium levels fell from 11.6 +/- 0.2 mg/dl before therapy to 10.7 +/- 0.6 mg/dl 2-3 days after starting hCT. The tolerance was excellent but, because of insufficient efficacy, we do not recommend this form of therapy for cancer hypercalcemia.

Retrobulbar optic neuritis after pamidronate administration in a patient with a history of cutaneous porphyria

We describe the case of a patient who developed reversible retrobulbar optic neuritis after intravenous pamidronate therapy for established osteoporosis. This possible complication has never been previously reported and, since our patient had a history of porphyria, it suggests that bisphosphonates should be administered cautiously in patients with this disease.

Molecular cytogenetic analysis of XX males using Y-specific DNA sequences, including SRY

XX maleness is the most common condition in which testes develop in the absence of a cytogenetically detectable Y chromosome. Using molecular techniques, it is possible to detect Yp sequences in the majority of XX males. In this study, we could detect Y-specific sequences, including the sex-determining region of the Y chromosome (SRY), using fluorescence in situ hybridization. In 5 out of 6 previously unpublished XX males, SRY was translocated onto the terminal part of an X chromosome. This is the first report in which translocation of an SRY-bearing fragment to an X chromosome in XX males could be directly demonstrated.

Intravenous pamidronate in patients with tumor-induced osteolysis: a biochemical dose-response study

Bisphosphonates are used increasingly in normocalcemic patients for treating tumor-induced osteolysis (TIO) but little is known about the metabolic effects and the most appropriate therapeutic regimen. In 21 patients with breast cancer and TIO, we determined the biochemical effects of a single infusion of pamidronate given at 30 mg (n = 5), 60 mg (n = 5), 90 mg (n = 5), or 120 mg (n = 6). Patients received no other systemic antineoplastic therapy during the trial. We selected patients with baseline fasting urinary Ca/Creat (creatinine) > 0.105 mg/mg (median value of our normal range) and they were followed weekly for up to 14 weeks. The biochemical effects were maximal at day 7. For the whole group, mean (+/- SEM) Ca/Creat levels fell from 0.208 +/- 0.018 to 0.048 +/- 0.008 mg/mg on day 7 and remained significantly ( p < 0.01) lower than baseline up to day 56. Hydroxyproline excretion fell to a lesser degree, from 7.0 +/- 1.2 to 4.0 +/- 0.6 mg x 100/mg of Creat. The falls in Ca/Creat and hydroxyproline excretion were dose-related (ANCOVA, p < 0.05). Changes in serum parameters of calcium metabolism were, however, not significantly dose-related. Serum Ca levels fell from 9.3 +/- 0.1 to 8.7 +/- 0.1 mg/dl on day 7, but not patients developed symptomatic hypocalcemia, and the decrease within each dose group was significant only at 120 mg. Ca2+ levels followed a similar pattern. There was a slight increase in Mg levels and a pronounced fall in Pi levels, from 3.6 +/- 0.2 to 2.8 +/- 0.1 mg/dl. Intact PTH levels increased from 29 +/- 4 to 91 +/- 13 pg/ml and remained significantly (p < 0.05) elevated up to day 28.(ABSTRACT TRUNCATED AT 250 WORDS)

Hypercalcaemia of melanoma: incidence, pathogenesis and therapy with bisphosphonates

Tumour-induced hypercalcaemia (TIH) is a frequent complication of advanced cancer but has been rarely reported in patients with malignant melanoma, and its pathogenesis remains unexplored. We studied eight patients with TIH and melanoma. We determined the incidence and pathogenesis of this complication and the effects of bisphosphonate therapy. The incidence of TIH in 751 patients with melanoma was 1.1%. All patients had liver and bone metastases at the time of hypercalcaemia. All patients had osteolytic lesions, most often multiple. The median survival was 30 days (range 4-136 days). After rehydration, the mean (+/- SEM) corrected calcium was 3.42 +/- 0.17 mmol/l. Parathyroid hormone levels were adequately suppressed and vitamin D concentrations were normal. Serum osteocalcin, a marker of bone formation, was low, except in the two patients with renal insufficiency, whereas fasting urinary calcium and hydroxyproline were increased, indicating inhibition of bone formation and stimulation of bone resorption. Increased parathyroid hormone-related protein secretion was noted in only one patient. Three of four patients became normocalcaemic after bisphosphonate therapy for a median duration of 2 weeks. In conclusion, hypercalcaemia is a rare complication of melanoma. It occurs in the context of far advanced disease and is essentially due to aggressive lytic bone metastases with an uncoupling in bone turnover. Bisphosphonates can offer short-term palliation.

Suppression of the inhibitory effect of denatured albumin on the polymerase chain reaction by sodium octanoate: application to routine clinical detection of hepatitis B virus at its infectivity threshold in serum

Ten to fifteen percent of posttransfusion viral hepatitis cases are still caused by HBV despite mandatory third generation screening procedures for HBsAg. There is thus an urgent need for a simple, time-cost-effective, but very sensitive test for routine HBV DNA detection in serum. Nested-primed PCR has been shown to detect purified HBV DNA at its infectivity threshold in serum. Since this is too labor-intensive for routine testing, we assessed the efficiency of a Fast PCR procedure, of three pairs of primers, and of thirty-five simple serum pretreatments with the aim to achieve the same sensitivity level. Using ten-fold dilution in phosphate buffered saline as pretreatment and Fast PCR for 99 cycles, we were able to detect HBV DNA at the 2 x 10(3)/ml level in serum. Using either NaOH denaturation or sodium octanoate thermoprotection as pretreatment and Fast PCR for 99 cycles, we were able to detect HBV DNA at its infectivity threshold in serum, while the classical phenol/chloroform/isoamylic alcohol/isopropanol/ethanol DNA purification procedure enabled us to reach the 10 virus particles/ml level. These results suggest that denatured albumin is responsible for the well known inhibitory effect of serum proteins on Taq polymerase. Because of its simplicity and its lower risk of sample-to-sample cross-contamination, the sodium octanoate thermoprotection method was chosen for routine clinical detection of HBV in serum. The clinical usefulness of this approach is demonstrated by the results obtained with HBsAg-negative acute hepatitis B incubation sera and with anti HBe-positive chronic hepatitis B sera.

A simple method for carbohydrate-deficient transferrin measurements in patients with alcohol abuse and hepato-gastrointestinal diseases

Carbohydrate-deficient transferrin (CDT) is known to be increased in alcohol abuse. Several methods were developed for its measurement (e.g. isoelectric focusing with Western blotting or immunofixation, anion-exchange chromatography followed by immunoassays). We describe a greatly simplified isoelectric focusing technique which does not require immunofixation. CDT results obtained with this method were compared to other biological markers of alcohol abuse, i.e. mean corpuscular volume (MCV), aspartate aminotransferase (ASAT) and gamma-glutamyl-transferase (GGT), in 55 patients distributed in three groups (i.e. healthy control subjects, control patients suffering from various hepato-gastrointestinal diseases and alcohol abusing patients). Sensitivity and specificity were 33-89%, 61-57%, 89-49% and 83-100% for MCV, ASAT, GGT and CDT, respectively. We conclude that our method is highly suitable for routine clinical use.

A novel MVMp-based vector system specifically designed to reduce the risk of replication-competent virus generation by homologous recombination

Recent work highlights the potential usefulness of MVM-based vectors as selective vehicles for cancer gene therapy (Dupont et al, Gene Therapy, 2000; 7: 790-796). To implement this strategy, however, it is necessary to develop optimized methods for producing high-titer, helper-free parvovirus stocks. Recombinants of MVMp (rMVMp) are currently generated by transiently co-transfecting permissive cell lines with a plasmid carrying the vector genome and a helper plasmid expressing the capsid genes (replaced with a foreign gene in the vector genome). The resulting stocks, however, are always heavily contaminated with replication-competent viruses (RCV), which precludes their use in vivo and particularly in gene therapy. In the present work we have developed a second-generation MVMp-based vector system specifically designed to reduce the probability of RCV generation by homologous recombination. We have constructed a new MVMp-based vector and a new helper genome with minimal sequence overlap and have used the degeneracy of the genetic code to further decrease vector-helper homology. In this system, the left homologous region was almost completely eliminated and the right sequence overlap was reduced to 74 nt with only 61% homology. We were thus able to substantially reduce ( approximately 200 x), but not completely eliminate, generation of contaminating viruses in medium-scale rMVMp preparations. Since the remaining sequence homology between the new vector and helper genomes is weak, our results suggest that contaminating viruses in this system are generated by nonhomologous recombination. It is important to note, unlike the autonomously replicating helper viruses produced from the first-generation vector/helper genomes, the contaminating viruses arising from the new packaging system cannot initiate secondary infection rounds (so they are not 'replication-competent viruses'). Our findings have important implications for the design of new MVMp-based vectors and for the construction of trans-complementing packaging cell lines.

Circulating concentrations of interleukin-6 in cancer patients and their pathogenic role in tumor-induced hypercalcemia

Circulating interleukin-6 (IL-6) concentrations correlate with disease activity in severe inflammatory conditions, in sepsis and in some hematological malignancies. On the other hand, IL-6 is a potent stimulator of osteoclastogenesis and has been implicated as a contributory factor in the genesis of osteopenic conditions. We measured circulating IL-6 levels by a sensitive (detection limit of 10 U/ml) and specific bioassay in 103 patients with advanced cancer, including 41 with tumor-induced hypercalcemia before any specific hypocalcemic therapy. We related IL-6 concentrations to clinical features and to biochemical parameters of bone metabolism, including blood Ca, Ca2+, Pi, intact parathyroid hormone, parathyroid hormone-related protein, osteocalcin, 1,25-(OH)2-vitamin D and, as markers of bone resorption, the fasting urinary excretion of calcium (Ca/creatinine) and hydroxyproline. IL-6 levels were increased, i.e. detectable, in 23% of the patients, 8/41 (20%) hypercalcemic and 16/62 (26%) normocalcemic patients (NS); the distribution of the values was similar in the two groups. The presence of increased IL-6 concentrations was not related to any clinical characteristic, notably not to the survival nor to the existence of bone metastases, whether in hypercalcemic or normocalcemic patients; e.g., only 3/12 (25%) hypercalcemic subjects without bone metastases had elevated IL-6 levels. We found no significant correlations between IL-6 concentrations and any of the biochemical parameters studied. Hypercalcemic subjects with increased IL-6 had higher urinary Ca/creatinine levels than patients with normal IL-6 levels (P < 0.005) but this was not the case in normocalcemic subjects. Mean concentrations of inflammatory or other bone metabolism markers were not significantly different between patients with normal or with elevated IL-6 levels. In summary, circulating IL-6 levels were increased in 23% of 103 patients with advanced cancer, but the frequency of increased IL-6 concentrations was not related to the presence of hypercalcemia or to any marker of calcium metabolism or bone turnover. The pathogenic importance of circulating IL-6 in patients with solid tumors remains to be demonstrated and our data indicate that increased circulating levels of IL-6, possibly reflecting the activation of the immune system, only contribute in a minor way to the osteolytic process in patients with tumor-induced hypercalcemia.

Response to alendronate in osteoporotic women previously treated with pamidronate

INTRODUCTION

Different bisphosphonates have been shown to increase bone mineral density (BMD) and reduce the risk of fracture in osteoporotic patients. It is unclear how shifting from a treatment with one bisphosphonate to another will influence the evolution of BMD and bone turnover.

METHODS

In the present study, we followed BMD (DXA, Hologic QDR1000) of the lumbar spine (BMDL) and of the total hip (BMDH), bone alkaline phosphatase (Ostase, Hibritech), and urinary collagen cross links (pyridinoline, deoxypyridinoline, Biorad) in 39 patients treated with IV pamidronate (60 mg/3 months) since at least 2 years and who were shifted to oral alendronate (10 mg/day, n=18) or left to IV pamidronate (n=21) for 2 more years.

RESULTS

BMD increased similarly and significantly in both groups after 2 additional years of treatment as compared to baseline (P<0.05, sign test). BMDL: +3.8% in the alendronate group vs +4.1% in the pamidronate group; BMDH: +4.3% in alendronate group vs +3.6% in pamidronate group, There was no significant change in the biological parameters of bone turnover in any group.

CONCLUSION

The increase of BMD with both bisphosphonates in these previously treated patients was as expected after a 2 more years of treatment. Alendronate administration did not induce a larger gain in BMD as compared to cyclic pamidronate. Bone turnover was no longer affected by switching the bisphosphonate treatment.

Reciprocal translocation between the proximal regions of the long arms of chromosomes 13 and 15 resulting in unbalanced offspring: characterization by fluorescence in situ hybridization and DNA analysis

We describe two female siblings with similar clinical features consisting of hydrocephalus, scaphocephaly, hypotonia, mongoloid eye slant, blepharophimosis, micrognathia, supernumerary mouth frenula and mental retardation. Routine cytogenetic studies in the elder patient did not reveal any abnormality, and initially it was assumed that the syndrome had an autosomal recessive inheritance. However, a slightly larger chromosome 13 was seen in routine G-banded metaphases of the mother and the youngest of the two siblings. A shorter chromosome 15 was detected in the mother only. High resolution banding showed that the abnormal chromosome 13 contained an extra G-positive band at 13q12. The short chromosome 15 in the mother appeared to have a deletion of band q12. Fluorescence in situ hybridization using DNA markers specific to chromosomes 13 and 15 unequivocally showed that the mother was a carrier of a balanced reciprocal translocation t(13;15)(q12;q13), whereas the youngest sibling's karyotype was 46,XX,-13,+der(15)t(13;15)(q12;q13)mat, resulting in partial monosomy 13pter----q12 and partial trisomy 15pter----q13. The proband is thus trisomic for the critical region responsible for Prader-Willi syndrome and Angelman syndrome; this was confirmed by DNA analysis demonstrating one paternal and two maternal alleles from multiallelic marker loci mapping to 15q11-q13. This report illustrates the sensitivity and specificity offered by fluorescence in situ hybridization and its usefulness in the diagnosis and delineation of subtle chromosomal rearrangements.

Tumor-induced hypercalcemia in a patient with extensive soft tissue sarcoma: effects of bisphosphonate therapy and surgery

Tumor-induced hypercalcemia (TIH) is a frequent complication of advanced cancer, but it has been rarely reported in patients with sarcoma. We describe the case of a young female patient with TIH and with an extensive synoviosarcoma of the left lower limb destroying the bony structures. Hypercalcemia was severe (18.3 mg/dl) and accompanied by low serum Pi and suppressed parathyroid hormone (PTH) and 1,25(OH)2 vit D3 serum concentrations. Hypercalcemia was successfully treated with ibandronate, a new third-generation bisphosphonate, and radical surgery was performed when the patient was normocalcemic. Circulating levels of PTH-related protein (PTHrP) were elevated at 22.5 pmol/L (NI < 9). PTHrP levels did not change after successful therapy of TIH, in contrast with PTH, which increased sharply. PTHrP levels were normalized after radical surgery. Moreover, low serum Pi with reduced threshold for phosphate excretion and increased tubular calcium reabsorption supported the notion that PTHrP was indeed the essential mediator of paraneoplastic hypercalcemia in this case despite the extensive bone destruction.