1180

receptor expression in the malignant cells may result inconsiderable elimination of LDL.Tumour cells may induce a more generalised increase in

LDL catabolism, perhaps via secretion of regulatorypeptides. Many humoral factors released by malignant cellshave been identified, some of which have a stimulatory effecton cell growth.20 Although no evidence exists that such amechanism operates in vivo, it is of interest that mitogenicsubstances such as platelet-derived growth factor stimulateLDL receptor expression in cultured cells.21Whether the expression of LDL receptors in tumour cells

may be used prognostically, as has been done for breastcancer,22 or therapeutically to supply the tumour withLDL-bound cytotoxic drugs23-25 remains to be studied.

We thank Ms Sabine Sullow and Ms Tatiana Egereva for technicalassistance and Ms Lena Ericsson for manuscript preparation. This study wassupported by the Swedish Medical Research Council (03X-7137).

Correspondence should be addressed to B. A., Department of Medicine,Huddinge University Hospital, S-141 86 Huddinge, Sweden.

REFERENCES

1. Sidney S, Farquhar JW. Cholesterol, cancer and public health policy. Am J Med 1983;75: 494-508.

2. Feinleib M. Review of the epidemiological evidence for a possible relationship betweenhypocholesterolemia and cancer. Cancer Res 1983; 43: 2503-07.

3. Cambien F, Ducimétière P, Richard J. Total serum cholesterol and cancer mortality ina middle-aged male population. Am J Epidemiol 1980; 112: 388-94.

4. Rose G, Shipley MJ. Plasma lipids and mortality: a source of error. Lancet 1980; ii:523-26.

5. Sherwin RW, Wentworth DN, Cutter JA, Hulley SB, Kuller LH, Stamler J. Serumcholesterol levels and cancer mortality in 361 662 men screened for the MultipleRisk Factor Intervention Trial. JAMA 1987; 257: 943-48.

6. Chao F-C, Efron B, Wolf P. The possible prognostic usefulness of assessing serumproteins and cholesterol in malignancy. Cancer 1975; 35: 1223-29.

7. Miller SR, Tartter PI, Papatestas AE, Slater G, Aufses AJ Jr. Serum cholesterol andhuman cancer. JNCI 1981; 67: 297-300.

8. Nydegger UE, Butler RE. Serum lipoprotein levels in patients with cancer. Cancer Res1972; 32: 1756-60.

9. Goldstein JL, Brown MS. The low-density lipoprotein pathway and its relation toatherosclerosis. Annu Rev Biochem 1977; 46: 897-930.

10. Ho YK, Smith RG, Brown MS, Goldstein JL. Low density lipoprotein (LDL)receptor activity in human acute myelogenous leukemia cells. Blood 1978; 52:1099-114.

11. Vitols S, Gahrton G, Ost A, Peterson CO. Elevated low density lipoprotein receptoractivity in leukemic cells with monocytic differentiation. Blood 1984; 63: 1186-93.

12. Vitols S, Gahrton G, Björkholm M, Peterson C. Hypocholesterolaemia in malignancydue to elevated low-density-lipoprotein-receptor activity in tumour cells: evidencefrom studies in leukaemic patients. Lancet 1985; ii: 1150-54.

13. Esposti PL. Cytologic malignancy grading of prostatic carcinoma by transrectalaspiration biopsy: a five-year-follow-up of 469 hormone treated patients. Scand JUrol Nephrol 1971, 5: 199-209.

14. Friedewald WT, Levy RI, Fredrickson DS. Estimation of the concentration oflow-density lipoprotein cholesterol in plasma, without use of the preparativeultracentrifuge. Clin Chem 1972; 18: 499-502.

15. Henriksson P, Einarsson K, Eriksson A, Kelter U, Angelin B. Estrogen-inducedgallstone formation in males. relation to changes m serum and biliary lipids duringhormonal treatment of prostatic carcinoma. J Clin Invest 1989; 84: 811-16.

16. Eriksson M, Berglund L, Rudling M, Hennksson P, Angelin B. Effects of estrogen onlow density lipoprotein metabolism in males: short-term and long-term studiesduring hormonal treatment of prostatic carcinoma. J Clin Invest 1989; 84: 802-10.

17. Kesaniemi YA, Grundy SM. The significance of low density lipoprotein production inthe regulation of plasma cholesterol level in man. J Clin Invest 1982; 70: 13-22.

18. Meddings JB, Dietschy JM. Regulation of plasma levels of low-density lipoproteincholesterol: interpretation of data on low-density lipoprotein turnover in man.Circulation 1986; 74: 805-14.

19. Ginsberg H, Gilbert H, Gibson JC, Le N-A, Brown WV. Increased low densitylipoprotein catabolism in myeloproliferative disorders. Ann Intern Med 1982; 96:311-16

20. Steel CM. Peptide regulatory factors and malignancy. Lancet 1989; ii: 30-34.21. Chait A, Ross R, Albers JJ, Bierman EL. Platelet-derived growth factor stimulates

activity of low density lipoprotein receptors. Proc Natl Acad Sci USA 1980; 77:4084-88.

22. Rudling MJ, Stăhle L, Peterson CO, Skoog L. Content of low density lipoproteinreceptors in breast cancer tissue related to survival of patients. Br Med J 1986; 292:580-82.

23. Mosley ST, Goldstein JL, Brown MS, Falck JR, Anderson RGW. Targeted killing ofcultured cells by receptor-dependent photosensitization Proc Natl Acad Sci USA1981; 78: 5717-21.

24. Firestone RA, Pisano JM, Falck JR, McPaul MM, Krieger M. Selective delivery ofcytotoxic compounds to cells by the LDL pathway. J Med Chem 1984; 27: 1037-43.

25. Vitols S, Masquelier M, Peterson C. Selective uptake of a toxic lipophilic anthracyclinederivative by the low-density lipoprotein receptor pathway in cultured fibroblasts.J Med Chem 1985; 28: 451-54.

COMPARISON OF THREE INTRAVENOUSBISPHOSPHONATES IN

CANCER-ASSOCIATED HYPERCALCAEMIA

STUART H. RALSTONUDAY PATEL

WILLIAM D. FRASER

STEPHEN J. GALLACHERFRANCES J. DRYBURGHROBERT A. COWAN

IAIN T. BOYLE

University Department of Medicine and Institute of Biochemistry,Glasgow Royal Infirmary, Glasgow G31 2ER

Summary Three intravenous bisphosphonates werecompared in the treatment of cancer-

associated hypercalcaemia. 48 patients were randomlyallocated to one of three treatment groups (each with 16subjects)—30 mg pamidronate or 600 mg clodronate, bothas single intravenous infusions; or etidronate as threeinfusions of 7·5 mg/kg per day for three consecutive days.Patients were rehydrated with normal saline before

bisphosphonate treatment. All three bisphosphonateslowered serum calcium by inhibiting bone resorption;pamidronate was the most potent in this respect. Bycomparison with the other groups, more patients in thepamidronate group became normocalcaemic, and the effecton serum calcium was apparent sooner and lasted longer.

Introduction

BISPHOSPHONATES are effective agents for the treatmentof cancer-associated hypercalcaemia because of their potentinhibitory effects on osteoclastic bone resorption.l-4Three compounds are generally available for clinical

use-pamidronate (aminohydroxypropylidene bisphos-phonate), clodronate (dichloromethylene bisphosphonate),and etidronate (hydroxy ethane bisphosphonate). Dose andduration of therapy have varied substantially betweenstudiesl-4 although current evidence indicates that, withpamidronate at least, there is little to choose between singleand multiple dose regimens.s Pamidronate is better thanconventional agents, such as mithramycin or the combina-tion of corticosteroids and calcitonin,’ but has not beencompared with the other two bisphosphonates. We have nowcarried out a randomised study of pamidronate, clodronate,and etidronate in cancer-associated hypercalcaemia.

Patients and Methods

48 consecutive patients who presented to Glasgow RoyalInfirmary and associated hospitals over a 12-month period werestudied. Most were referred for treatment of symptoms associatedwith "significant" hypercalcaemia, defmed as a presenting serumcalcium concentration (adjusted for albumin) of 2-80 mmol/1 ormore.

All patients were rehydrated initially with at least 6 1 ofintravenous 0-9% sodium chloride solution over 48 h before beingrandomised to one of three bisphosphonate regimens-intravenousinfusion of etidronate 7-5 mg/kg body weight in 500 ml 09% salineover 2 h, for 3 consecutive days; single intravenous infusion ofclodronate 600 mg in 500 ml 0-9% saline over 6 h; singleintravenous infusion of pamidronate 30 mg in 0 9 % saline over 4 h.7 patients, who had a favourable clinical and biochemical responseto intravenous etidronate were given additional oral etidronatetherapy (20 mg/kg/day) 4-6 days after starting intravenous therapy.Blood and second-voided urine samples were obtained after an

overnight fast. Total calcium measurements were adjusted foralbumin concentration by use of an algorithm In a patient withmyeloma whose serum globulin levels were greatly increasedionised calcium was also measured, but was equivalent to thatpredicted by the albumin-adjusted value.

1181

PATIENT CHARACTERISTICS AFTER INITIAL REHYDRATION

Values are means (SEM).*All but one were squamous carcinomas; tbladder, kidney, anaplastic,tongue; tbladder, kidney, skin, prostate, oesophagus, adenocarcinomaunknown primary site; §stomach, cervix, larynx, adenocarcinoma unknownprimary site (2).

Variables derived from biochemical measurements included-

fasting urinary calcium/urinary creatinine ratio (Ca/Cr); thresholdfor renal tubular calcium reabsorption (calculated by means of acomputer program, Rorer Pharmaceuticals, Eastbourne, UK,TmCa/GFR where GFR is glomerular filtration rate); threshold forrenal tubular phosphate reabsorption (determined from a

nomogram, TmP/GFR);8 sodium excretion index ([urinarysodium/urinary creatinine] multiplied by serum creatinine, NaE).

Patients were asked about symptoms of hypercalcaemia-nausea;vomiting; anorexia; constipation; confusion, coma, or drowsiness;polyuria; polydipsia or dry mouth; bone or visceral pain; malaise orfatigue were recognised as separate symptoms. Symptoms presentbefore treatment were given a score of 1. Symptoms that had or hadnot improved after treatment were given scores of 0 or 1

respectively. The total number of patient-symptoms before andafter treatment was used as an assessment of symptomatic response.Data were analysed by Student’s t test, X2, and, when distribution

was non-parametric, the Mann-Whitney U test.

Results

The clinical and biochemical details (after the initial

period of rehydration), were similar for the patients in thethree treatment groups (table).Hypercalcaemia improved after sodium repletion, with

serum calcium values falling from a mean of 3-45 (95%confidence intervals, CI, 3-34-3-56) at presentation to 3-25(CI, 3-14-3-36) mmol/1 (n=48; p<0001). In response to

bisphosphonate therapy, serum calcium values fell further(fig 1). The fall was slightly more rapid in the pamidronategroup (significant from day 1, p<0-05) than in theclodronate and etidronate groups (significant from day 2,p < 0-05). Serum calcium values at day 6 were lower withpamidronate than with clodronate (p<0’01) or etidronate

(p < 0001). On day 6, 14 of 16 patients in the pamidronategroup were normocalcaemic, compared with 6 of 16 in theclodronate group and 5 of 16 in the etidronate group. Therewas no significant difference between the serum calcium ofpatients in the etidronate group who were given oraletidronate and those who were not.The response to pamidronate was longer than with the

other agents; in the pamidronate treated patients (who hadreceived no other medication) the median time to relapsewas 29 (range, 18-90) days (n = 6), compared with 12 (9-45)days in the clodronate group (n = 7), and 10-5 (6-20) days inthe etidronate group (n = 8). The 8 etidronate treatedpatients for whom information on relapse was available hadhigher pre-treatment calcium values than those in the othertwo groups. However the time to relapse, 12 (6-20) days,

Fig 1-Effect of bisphosphonates on serum calcium.

Points are means; bars are 95% confidence intervals; reference range isindicated by horizontal interrupted lines. On day 9 the numbers of patientsavailable for analysis had fallen to 12, 14, and 10 in the pamidronate,clodronate, and etidronate groups respectively.

remained similar in the etidronate group, when the analysiswas repeated in a subgroup of 5 patients who were matchedfor severity of hypercalcaemia.

Fasting urinary Ca/Cr ratio fell in each of the treatmentgroups; post treatment values on day 6 were significantlylower in the pamidronate group, when compared with theendronate (p<001) and clodronate (p<005) groups (fig2).

Renal function, as assessed by serum creatinine

concentration, improved the period of rehydration from

Fig 2-Effect of bisphosphonates on urinary calcium excretion.

Points are means; bars are 95% confidence intervals; reference rangeindicated by horizontal interrupted lines. On day 9, the numbers of Ca/Crobservations available for analysis had fallen to 7, 12, and 7 in the

pamidronate, clodronate, and etidronate groups, respectively.

1182

mean 117 (CI 99-135) &micro;mo1/1 to 106 (91-121) &micro;mo1/1,p<0 001. Thereafter, serum creatinine was similar for thethree groups. Severe deterioration in renal function wasnoted in one etidronate-treated patient.

After bisphosphonate therapy, there was little change inthe renal calcium reabsorption threshold in the threetreatment groups: Tm Ca/GFR day 6 mean (SEM) 2-30(0-12)-pamidronate; 2-17 (0-10)-clodronate; 2-16 (0-08)- etidronate. These findings indicate that the lowering ofserum calcium with bisphosphonate therapy is due toreduction in bone resorption, rather than a change in renaltubular reabsorption of calcium.

Symptomatic response was better in the pamidronate andclodronate groups than in the etidronate group: mean

symptoms per patient before treatment were 2-9, 2-7, and2-9 (pamidronate, clodronate and etidronate respectively)falling to 07, 0-7, and 1-6 respectively after treatment.

1 patient in each of the three treatment groups died ofprogressive cancer on day 7 post-treatment. In theetidronate group, 2 more patients died on days 6 and 9, withpoorly controlled hypercalcaemia and 1 died on day 7 withprogressive renal dysfunction. 1 patient relapsed on day 6with poorly controlled hypercalcaemia (serum calcium 4-00mmol/1) that responded to calcitonin.

Discussion

All three bisphosphonate regimens caused a significantfall in serum calcium values from those achieved byrehydration. However, with the pamidronate treated groupthe onset of effect was most rapid, more profound 6 daysafter treatment and longer in duration compared with theother two groups. In the etidronate-treated patients,additional etidronate given orally had no significant effect onserum calcium, in contrast to findings of other workers. 9With the exception of some patients with rapidly

progressive tumours, the clinical response reflected thebiochemical response; however, we acknowledge that

symptom assessment was not "blind" and therefore open toobserver bias.The hypercalcaemia in our patients was due to increased

bone resorption and increased renal tubular calcium

reabsorption, possibly mediated by parathyroid hormonerelated peptides.10-14 The mechanism of action of the threebisphosphonates appeared to be similar-the suppression ofbone resorption. 1.15.16-there was no significant effect of thebisphosphonate on renal tubular calcium handling.5,15Return of serum calcium values to normal occurred in a highproportion of pamidronate treated patients. The potentinhibition of bone resorption by pamidronate, after initialsodium repletion,15 resulted in normocalcaemia despitehumorally mediated increases in renal tubular calcium

reabsorption. Experimental evidence indicates that the

greater efficacy of pamidronate observed in this study mayrelate to different mechanisms of action from those ofetidronate and clodronate. All three bisphosphonatesinhibit bone resorption in organ culture in descending orderof potency; etidronate > clodronate > pamidronate.Pamidronate is unique in inhibiting osteoclast formationand/or recruitment at concentrations 100-fbld lower.17,18 Themore profound calcium lowering effect of pamidronate whichwe observed probably reflects the importance of inhibition ofosteoclast recruitment in the action of pamidronate.

It is possible that the doses of etidronate and clodronatewere insufficient to provide a fair comparison with the morepotent pamidronate. However, the bisphosphonate doses

used were those generally recommended in previousarticlesl 5 for the management of cancer-associated

bisphosphonate and higher doses were unlikely to be moreeffective .24,1921 With higher doses of clodronate and

etidronate there is an increased risk of renal failure.22 Renalfunction did not deteriorate in patients given pamidronate orclodronate whereas significant renal impairment developedin 1 etidronate-treated patient.Our findings show that at the doses commonly used in

clinical practice, a single infusion of pamidronate is moreeffective in controlling cancer-associated hypercalcaemia thanis a single infusion of clodronate or three consecutive infusionsof etidronate. These observations, and our earlier results,ssuggest that intravenous pamidronate may be the current

treatment of choice for cancer-associated hypercalcaemia.We thank the many physicians, surgeons, radiotherapists, and oncologists

who kindly referred patients for inclusion in this study. We also thankCiba-Gcigy (UK) for kindly donating the pamidronate, MCPPharmaceuticals (UK) for the clodronate, and Norwich EatonPharmaceuticals for the etidronate.

Correspondence should be addressed to S. H. R., Rheumatic DiseasesUnit, Northern General Hospital, Ferry Road, Edinburgh EH5 2DQ.

REFERENCES

1. Sleeboom HP, Bijvoet OLM, van Oosteroom AT, Gleed JH, O’Riordan JLH.Comparison of intravenous (3-amino-1-hydroxypropylidene) 1,1-bisphosphonateand volume repletion in cancer-associated hypercalcaemia. Lancet 1983; i: 239-43.

2. Jacobs TP, Sins ES, Bilezekian JP, Baquiran DC, Shane E, Canfield RE.

Hypercalcemia of malignancy: treatment with intravenous dichloromethylenediphosphonate. Ann Intern Med 1981, 94: 3212-16.

3. Jung A Comparison of two parenteral diphosphonates in hypercalcemia of

malignancy. Ann Intern Med 1972; 29: 923-30.4. Ryzen E, Martodam RR, Troxell M, et al. Intravenous etidronate in the management

of malignant hypercalcemia. Arch Intern Med 1985, 145: 449-525. Ralston SH, Alzard AA, Gallacher SJ, Gardner MD, Cowan RA, Boyle IT. Clinical

experience with aminohydroxypropylidene bisphosphonate in the management ofcancer-associated hypercalcaemia Q J Med 1988; 258: 825-34

6. Ralston SH, Gardner MD, Dryburgh FJ, Jenkins AS, Cowan RA, Boyle ITComparison of aminohydroxypropylidene disphosphonate, mithramycin, andcorticosteroid calcitonin in treatment of cancer-associated hypercalcaemia Lancet1985, ii: 907-10

7. Gardner MD, Dryburgh FJ, Fyffe JA, Jenkins AS. Predictive values of derivedcalcium figures based on the measurement of ionised calcium Ann Clin Biochem1981, 18: 106-09

8. Walton RJ, Bijvoet OLM. Nomogram for the determination of renal thresholdphosphate concentration. Lancet 1975, ii: 309-10.

9 Ringenberg QS, Ritch PS. Efficacy of oral administration of etidronate disodium inmaintaining normal serum calcium levels in previously hypercalcaemic cancerpatients. Clin Ther 1987; 9: 1-7

10. Ralston SH. The pathogenesis of humoral hypercalcaemia of malignancy Lancet

1987; ii: 1443-4611. Ralston SH, Fogelman I, Gardner MD, Dryburgh FJ, Cowan RA, Boyle IT

Hypercalcaemia of malignancy: evidence for a non-parathyroid humoral agent withan effect on renal tubular calcium handling Clin Sci 1984; 66: 187-91

12. Kemp BE, Moseley JM, Rodda CP, et al. Parathyroid hormone-related protein ofmalignancy: active synthetic fragments. Science 1987; 238: 1568-70.

13. Yates AJP, Gutierrez GE, Smolens P, et al. Effects of a synthetic peptide of aparathyroid hormone related protein on calcium homeostasis, renal tubular calciumreabsorption and bone metabolism in vivo and in vitro in rodents. J Clin Invest1988; 81: 932-38.

14. Broadus AE, Mangin M, Insogna KL, Weir EC, Burtis WJ, Stewart AF Humoralhypercalcaemia of cancer. Identification of a novel parathyroid-hormone-relatedpeptide N Engl J Med 1988; 319: 556-63

15. Harinck HIJ, Bijvoet OLM, Platingh AST, et al Role of bone and kidney in

tumor-induced hypercalcaemia and its treatment with bisphosphonate and sodiumchloride Am J Med 1987, 82: 1133-42.

16. Kanis JA, Urwin GH, Gray RES, et al. Effects of intravenous etidronate disodium onskeletal and calcium metabolism. Am J Med 1987; 82 (suppl 2A) 55-70

17. Boonekamp PM, van der Wee-Pals LJA, van Wijk-van Leenep M, Thesing CW.Bijvoet OLM Two modes of aciton of bisphosphonates on osteoclastic resorptionof mineralised matrix. Bone and Mineral 1986; 1: 27-39.

18. Hughes DE, McDonald BR, Russell RGG, Gowen M Inhibition of osteoclast-likecell formation by bisphosphonates in long-term cultures of human bone marrow JClin Invest 1989 (in press)

19. Bonjour JP, Phillipe J, Guelpa G, Bisetti A, Rizzoli R, Jung A, Rosini S, Kanis JABone and renal components in hypercalcaemia of malignancy and response to asingle infusion of clodronate. Bone 1988; 9: 123-30.

20. Adami S, Bolzicci GP, Rizzo A, et al. The use of dichloromethylene bisphosphonateand aminobutane bisphosphonate in hypercalcaemia of malignancy Bone andMineral 1987, 2: 395-404.

21. Hasling C, Charles P, Mosekilde L. Etidronate disodium in the management ofmalignancy-associated hypercalcaemia Am J Med 1987; 2A (suppl) 51-54

22. Bounameaux H, Schifferli J, Montani JP, Jung A, Chatelanat F. Renal failureassociated with intravenous diphosphonates Lancet 1983; i: 471