phase i study of lovastatin, an inhibitor of the ...pathway by lovastatin, a fungal antibiotic used...

Vol. 2, 483-491, March 1996 Clinical Cancer Research 483

3 The abbreviation used is: HMG-CoA, 3-hydroxy-3-methylglutaryl co-

enzyme A.

Phase I Study of Lovastatin, an Inhibitor of the Mevalonate

Pathway, in Patients with Cancer

Alain Thibault,” 2 Dvorit Samid,2

Anne C. Tompkins, William D. Figg,

Michael R. Cooper,2 Raymond J. Hohl,

Jane Trepel, Bertrand Liang, Nicholas Patronas,

David J. Venzon, Eddie Reed,

and Charles E Myers2Clinical Pharmacology Branch IA. T.. D. S., A. C. T.. M. R. C..

W. D. F., J. T., B. L.. E. R., C. E. M.] and Biometrics Section[D. J. V.�. National Cancer Institute and Neuro-RadiologyDepartment. Warren Magnussen Clinical Center IN. P.].NIH, Bethesda, Maryland 20892-1576. and Divisions of

Hematology-Oncology and Clinical Pharmacology, University of

Iowa College of Medicine, Iowa City, Iowa 52242 [R. J. H.]

ABSTRACTLovastatin, an inhibitor of the enzyme 3-hydroxy-3-

methylglutaryl-coenzyme A reductase (the major regulatory

enzyme of the mevalonate pathway of cholesterol synthesis),

displays antitumor activity in experimental models. We

therefore conducted a Phase I trial to characterize the tol-

erability of lovastatin administered at progressively higher

doses to cancer patients. From January 1992 to July 1994, 88

patients with solid tumors (median age, 57 ± 14 years) were

treated p.o. with 7-day courses of lovastatin given monthly

at doses ranging from 2 to 45 mg/kg/day. The inhibitory

effects of lovastatin were monitored through serum concen-

trations of cholesterol and ubiquinone, two end products of

the mevalonate pathway. Concentrations of lovastatin and

its active metabolites were also determined, by bioassay, in

the serum of selected patients. Cyclical treatment with by-

astatin markedly inhibited the mevabonate pathway, evi-

denced by reductions in both cholesterol and ubiquinone

concentrations, by up to 43 and 49% of pretreatment values,

respectively. The effect was transient, however, and its mag-

nitude appeared to be dose independent. Drug concentra-

tions reached up to 3.9 �LM and were in the range associated

with antiproliferative activity in vitro. Myopathy was the

dose-limiting toxicity. Other toxicities included nausea, di-

arrhea, and fatigue. Treatment with ubiquinone was associ-

ated with reversal of bovastatin-induced myopathy, and itsprophylactic administration prevented the development of

this toxicity in a cohort of 56 patients. One minor response

was documented in a patient with recurrent high-grade

glioma. Lovastatin given p.o. at a dose of 25 mg/kg daily for

Received S/I 8/95; revised 9/25/95; accepted I 1/21/95.

I To whom requests for reprints should be addressed. at University of

Virginia Health Sciences Center, Division of Hematology-Oncology,

Jordan Hall. P. 0. Box 513, Charlottesville, VA 22908.2 Present address: Cancer Center, University of Virginia Health Sci-ences Center. Charlottesville. VA 22908.

7 consecutive days is well tolerated. The occurrence of my-

opathy, the dose-limiting toxicity, can be prevented by

ubiquinone supplementation. To improve on the transient

inhibitory activity of this dosing regimen on the mevalonate

pathway, alternative schedules based on uninterrupted ad-

ministration of bovastatin should also be studied.

INTRODUCTIONThe role of lipid metabolism in cancer was initially inves-

tigated in the 1950s by Fumagalli et al. (1) who observed that

neoplastic cells synthesize large quantities of cholesterol from

precursors such as acetate and mevalonate. They concluded that

this ‘ ‘high rate of cholesterol synthesis may provide a useful

basis for testing whether tumor growth can be inhibited by

impairing its sterol synthesis’ ‘ ( 1 ). Twenty years later, Maltese

(2) demonstrated that the activity of HMG-CoA3 reductase, the

major regulatory enzyme of de novo cholesterol synthesis, was

increased in neoplastic tissue. This enzyme catalyzes the for-

mation of mevalonate, which is also the precursor of isoprenoid

moieties that are incorporated into or linked to several mole-

cules essential for cell growth and replication. The latter include

ubiquinone (an isoprenylated benzoquinone involved in the mi-

tochondrial electron transfer chain), dolichol, haem A, isopentyl

transfer RNA, and several proteins involved in signal transduc-

tion (Fig. 1 ; for review, see Ref. 3). The scope of these obser-

vations was later broadened when it was shown that inhibition

of HMG-CoA reductase by lovastatin selectively inhibited tu-

mor growth in vitro and in animal models of hepatocellular.

pancreatic, and central nervous system tumors (4-7). These

studies demonstrated that growth arrest was associated with

marked inhibition of isoprenoid synthesis and could be achieved

with minimal toxicity to the tumor-bearing animals, including

the absence of myelosuppression.

These findings suggested that inhibition of the mevalonate

pathway by lovastatin, a fungal antibiotic used in the treatment

of hypercholesterolemia (8), may offer a novel approach to the

treatment of cancer. We therefore designed a Phase I study to

determine the maximum tolerated dose of bovastatin when ad-

ministered at progressively higher doses to patients with cancer.

The study rationale was to attempt to achieve in patients drug

concentrations associated with the experimental antiprolifera-

tive activity. It was supported by animal toxicology studies

which indicated that much higher doses of lovastatin than are

currently recommended for the treatment of hypercholesterol-

emia (up to 80 mg/day, or 1 mg/kg/day) could be administered

for short periods of time and be well tolerated (9). This infor-

mation led us to administer lovastatin in cycles, to allow for

recovery from acute drug-induced toxicity, while preserving the

Research. on February 23, 2020. © 1996 American Association for Cancerclincancerres.aacrjournals.org Downloaded from

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Acetyl CoA

IAcetoacetyl CoA

3 Hydroxy-3 Methyl Glutaryl CoA

HMG-CoA reductase 1- LOVASTATIN

IFarnesyl-PP

ISqualene

I

I

484 Phase I Study of Lovastatin

II

Mevalonate

IMevabonate-PP

IIsopentenyl-PP

I. isopentenyl t-RNA

Geranyl-PP

Desmosterol

Geranylgeranyl-PP

. haem A

. farnesylated proteins

. side chain of ubiquinone

. geranylgeranylated proteins

. dolichol

Cholesterol

Fig. 1 Outline of the mevalonate pathway. The rate-limiting step is catalyzed by HMG-CoA reductase and inhibited by lovastatin. End productsinclude cholesterol, a cell membrane component; ubiquinone, an electron carrier of the respiratory chain; and isoprenoid moieties, required for the

posttranslational processing of proteins involved in intracellular signaling.

potential for drug activity. The secondary objectives of the trial

were to quantitate the pharmacological effects of high-dose

lovastatin in humans and to evaluate the clinical efficacy of

ubiquinone supplementation in the prevention of lovastatin-

induced rhabdomyolysis, since there is evidence that ubiquinone

depletion may play a role in the pathophysiology of this side

effect(lO, 11).

PATIENTS AND METHODS

Patient Population

Adults with a histological diagnosis of cancer confirmed by

the Pathology Department of the NIH Clinical Center were

eligible for this Phase I trial. Other inclusion criteria included:

Eastern Cooperative Oncology Group performance status of 2 or

better, ability to take p.o. medication, hemoglobin concentration

>9.0 mg/dl, platelet count > 100,000/mm3, absolute granulo-

cyte count > 1 ,500/mm3, normal prothrombin time and activated

partial thromboplastin time, serum alanine transferase concen-

trations less than twice the upper limit of normal, total bilirubin

within the normal range, and and serum creatinine concentration

of 2.0 mg/dl or less. Patients were ineligible if they had exten-

sive (>50%) liver replacement by tumor or if they had not

recovered from the toxicities of previous radiation or chemo-

therapy, or if they had received such therapy within a 4-week

period. Patients had to have failed standard therapy for their

disease or harbor a disease for which no acceptable therapy is

known. For example, patients with prostate cancer were re-

quired to have disease progression despite total androgen block-

ade therapy (hormone-independent prostate cancer) and subse-

quent cessation of flutarnide therapy. Patients with primary

central nervous system tumors had to have undergone maxi-

mally tolerated surgery followed by radiation therapy. Previous

treatment with adjuvant or palliative chemotherapy was not

required, nor did it constitute an exclusion criterion. No other



Clinical Cancer Research 485

form of antitumor therapy was allowed during the study period.

Patients taking anticonvulsants and corticosteroids were main-

tamed on the same therapy. The dosage of anticonvulsants was

modified according to symptoms and plasma concentrations.

The dose of corticosteroids was kept identical to preprotocol

conditions or decreased as a function of clinical improvement.

All patients or their proxy signed an informed consent document

in compliance with the rules of the National Cancer Institute’s

Institutional Review Board.

Initial Clinical Evaluation

Each patient underwent a complete history and physical

examination along with an assessment of the performance sta-

tus. Pretreatment laboratory investigations included a hemogram

with leukocyte differential and platelet count, standard serum

biochemistry and coagulation studies, urinalysis, tumor markers

relevant to the tumor type, total and high-density lipoprotein

cholesterol, triglycerides, ubiquinone, chest X-ray, and electro-

cardiogram. Radiological studies appropriate to the disease type

and location were obtained within 4 weeks of entering protocol.

Treatment

Preclinical toxicology and pharmacology, available in the

mouse, rat, rabbit, and dog (9), demonstrated linear pharmaco-

kinetics in every species and indicated that doses up to 200

mg/kg/day would yield drug concentrations in the range of 2-20

p.M. Although the maximum tolerated dose and organ toxicity

differed among species, progressive anorexia and death devel-

oped after 9-14 days of uninterrupted drug administration to

rabbits (the most sensitive species) and was associated with

sustained drug concentrations of 20-25 JiM. In contrast, circu-

lating concentrations of 2-4 �i.M were well tolerated for months

in all animal models. For the purposes of this Phase I study,

intermittent drug administration, starting at a dose of 2 mg/kg/

day, was therefore predicted to be well tolerated.

Lovastatin (Mevacor; Merck, West Point, PA) was admin-

istered p.o. following a four times a day schedule, for 7 con-

secutive days, in monthly cycles. The trial was initially con-

ducted over seven dose levels, ranging from 2 to 45 mg/kg/day

(2, 4, 6, 8, 10, 25, and 45 mg). The initial dose level was twice

the dose currently recommended for prolonged administration in

humans and was chosen based on the preclinical information

and unpublished safety data made available by the manufac-

turer. The large dose increments of the last two dose levels were

arbitrarily chosen based on the paucity of toxicity episodes at

the first five dose levels. At least three new patients were treated

at each dose level. The first cycle of therapy was administered

in the outpatient clinic of the Clinical Pharmacology Branch,

National Cancer Institute. Patients then returned home and were

subsequently seen monthly. Compliance with the p.o. regimen

was monitored through pill count and weekly telephone inter-

views. In the absence of disease progression or severe (grade 3

or greater) drug-induced toxicity, treatment cycles were re-

peated every 4 weeks. The dose of lovastatin could be increased

for a given patient from one cycle to the next, according to the

dose escalation schedule, provided the preceding cycle had been

well tolerated in that patient and shown to be safe in at least

three new patients. The occurrence ofdose-limiting myopathy at

45 mg/kg/day prompted us to return to the 25-mg/kg/day dose

level and subsequently characterize the 30- and 35-mg/kg/day

dose levels. In a second part of the trial, lovastatin was given at

four dose levels (30, 35, 40, and 45 mg/kg/day) while coadmin-

istering ubiquinone (Vitaline Corporation, Ashland, OR) p.o.

(240 mg daily, in four divided doses, given at the same time as

lovastatin) to prevent lovastatin-induced myotoxicity. Supple-

mentation started 7 days before the initiation of bovastatin and

continued for as long as the patient remained on protocol. Other

hypolipidemic drugs (niacin, fibric acid derivatives, and other

HMG-CoA reductase inhibitors) were not concurrently admin-

istered.

Biochemical Measurements

Frequency of Laboratory Evaluation. Initially, the co-

hort of patients treated with lovastatin alone had blood drawn on

days 0, 1 . 3, 5, 8, and 28 of each cycle of therapy. Additional

blood was obtained from most patients on days 15 and 21 . The

cohort treated with lovastatin in combination with ubiquinone

was monitored on the day ubiquinone supplementation began

(day -7), on the day treatment with lovastatin began (day 1),

and subsequently on days 3, 5, 8, 15, 21, and 28. As a rule, blood

samples were obtained prior to the administration of the morn-

ing dose of lovastatin.

Measurement of Pharmacological Parameters. The

following biochemical effects of lovastatin therapy were mon-

itored: (a) inhibition of cholesterol synthesis, by measuring

serum total and high-density lipoprotein cholesterol; (b) inhibi-

tion of the synthesis of isoprenylated end products of the me-

valonate pathway, by measuring serum ubiquinone concentra-

tions; and (c) circulating concentrations of lovastatin and its

metabolites.

Measurements of Ubiquinone Concentrations in Blood.

Serum ubiquinone concentrations were assayed by normal phase

high-performance liquid chromatography according to a method

previously described by Abe et a!. ( 12). The assay was linear

between 0.08 and 10.67 �.g/ml (r� = 0.995 + 0.009, mean ±

SD; n = 12 standard curves), with a coefficient of variation

< 17%. The lower limit of quantification was 0.08 p.g/ml.

Measurements of Lovastatin Concentrations in Blood.

Serum concentrations of lovastatin and its metabolites, which

are also responsible for inhibition of HMG-CoA reductase in

vivo, were measured indirectly and retrospectively from serum

samples collected for other monitoring purposes. The method

used was a standardized bioassay which quantitates the total

inhibitory activity of a patient’s serum (referred to as drug

concentrations, in this report) against a microsomal suspension

of HMG-CoA reductase (13). The lower limit of quantification

was 0.03 �M.

Assessment of Toxicity

The laboratory evaluation of toxicity was implemented by

weekly hemograms with leukocyte differential and platelet

count, electrolytes, blood urea nitrogen, creatinine, albumin, and

total protein. Since myopathy and elevations of hepatic

transaminases have been recognized in 0.2-2% of patients tak-

ing lovastatin for the treatment of hypercholesterolemia (14),

patients were specifically monitored for the possible occurrence




of these events with measurements of hepatic aminotransferases,

bilirubin (total and direct), alkaline phosphatase, lactate dehy-

drogenase, creatine phosphokinase with isoenzyme fraction, and

aldobase. Urinalysis and urine dipstick for myoglobin (positive

hemoglobin reaction) were also performed. Toxicity was graded

according to the National Cancer Institute Common Toxicity

Criteria. Since no standard criterion exists for the grading of

musculoskeletal toxicity, the following scale was used: myalgias

for <2 days without elevations of serum creatine phosphokinase

represented grade 1 toxicity; myalgias of >2 days duration or

elevations of serum creatine phosphokinase to < 10 times the

upper limit of normal defined grade 2 toxicity; and muscle pain,

falls, or weakness sufficient to prevent the performance of daily

activities and/or elevations of serum creatine phosphokinase

concentrations to 10 times the upper limit of normal or above

were defined as grade 3 toxicity. If, at any dose level, one

patient developed grade 3 toxicity or above, additional patients

were entered at that dose level until at least six patients had been

treated. Dose escalation was stopped once grade 3 or higher

toxicity developed in two of the six patients. The next lower

dose of lovastatin was defined as the maximum tolerated dose

and at least three additional patients were treated at this lower

dose to confirm its safety.

Assessment of Response

The response status of malignancies was determined

monthly, prior to each cycle of therapy, using conventional

anatomical criteria (15). For patients with prostate cancer, the

criteria from the National Prostate Cancer Project ( 16) and

published criteria for decline in prostate-specific antigen were

used ( 1 7, 1 8). A technetium bone scan was obtained every 3

months if initially positive or in the presence of new bone

symptoms. The assessment of patients with gliomas is compli-

cated by the variability in tumor-associated edema and its re-

sponse to steroid therapy, and technical factors which preclude

using the intensity of gadolinium enhancement on magnetic

resonance imaging to determine tumor response. In these pa-

tients, special attention was therefore paid to changes in perfor-

mance status and steroid requirements, which were assessed at

each visit. Complete response was defined as complete disap-

pearance of lesions on magnetic resonance imaging (assessment

performed in two different planes) and weaning from steroids.

Partial and minor responses were defined by conventional ana-

tomical criteria, absence of deterioration in performance status,

and stable or decreased corticosteroids requirements. Progres-

sive disease was defined by either anatomical criteria, deterio-

ration in performance status, or the need to increase steroid

doses to maintain function. Disease stabilization was defined as

the absence of a significant (more than 25%) increase or de-

crease in tumor size while the patient maintained or improved

performance status compared to pretreatment level. Disease

stabilization in these patients had to be maintained for at least 3

months to be considered significant.

Statistical Methods

Trend analysis of cholesterol change and lovastatin dose

was performed using the Spearman rank correlation method

( I 9). Changes from pretherapy ubiquinone concentrations to

Table 1 Demographic and treatment characteristic s of the study

population

Characteristic n

Median age, 57 ± 14Performance status (Eastern Cooperative

Oncology Group scale)Grade 0 21

Grade I 53Grade 2 14

Previous therapySurgery 44Radiation 54Chemotherapy 67Hormonotherapy 46

Tumor typeProstate (hormone independent) 38

Primary central nervous system 24

Astrocytoma 12

Glioblastoma 8Anaplastic oligodendroglioma 2

Others 2Breast 7Colorectal 4Ovary 4Sarcoma 3

Lung 2

Others 6

nadirs while receiving lovastatin were assessed with the Wil-

coxon signed rank test (19). Cholesterol declines in the two

patient groups (one supplemented with ubiquinone, the other

not) were compared using the Wilcoxon rank sum test (19).

Least-squares linear regression was used to test for trends in

circulating drug concentrations, which were logarithmically

transformed before analysis. The distributions of toxicities

across grade and dose level were compared using the Cochran-

Armitage test (20). SAS (Version 6.04; SAS Institute, Cary,

NC) and StatXact (Version 2.04a; Cytel Software Corp., Cam-

bridge, MA) statistical packages were used for all analyses.

RESULTSPatient Characteristics. Eighty-eight Caucasian pa-

tients (63 men and 25 women) entered the trial from January

1992 to July 1994. The demographic and treatment character-

istics of the study population are shown in Table 1 . All patients

(other than prostate and brain cancer patients) had failed at least

one course of chemotherapy with doxorubicin and/or cyclophos-

phamide (breast cancer and sarcoma), cisplatin or Taxol (ovar-

ian cancer), and 5-fluorouracil (colon cancer). Patients with

primary brain tumors and hormone-independent prostate cancer

made up the two largest cohorts of the trial (39 and 24 patients,

respectively).

Pharmacological Parameters. A total of 200 cycles of

therapy was administered over 13 dose levels (Table 2). Forty-

five patients received only one cycle of lovastatin, and 43 were

given more than one (occasionally administered at different

doses since dose escalation was allowed in 16 patients). To

simplify the analysis, therefore, only data from the first cycle of

therapy for each treated patient has been used to characterize the

pharmacological effects of lovastatin. All cycles of therapy were



80

70

. 60

.� 50

�- 40

30

20

10

“ Numbers in parentheses. number of patients escalating from

lower dose level.

2 4 6 8 10 25 30 35 45

Lovastatin dose(mg/kg/day)

Fig. 2 Pharmacological effects of lovastatin. Percentage of decline in

serum concentrations of cholesterol (�) and ubiquinone (�) as a func-

tion of bovastatin dose (mean). Ubiquinone concentrations were deter-

mined only in patients treated at the 25-mg/kg/day dose level or higher.

Bars, SE.


Table 2 Distribution of patien ts and number of cy des per dose level

Lovastatin dose Patients” Cycles

(mg/kg/day) (n) (n)

2 4 8

4 5(1) 7

6 4(1) 7

8 3 3

10 4 7

25 13(2) 23

30 8 18

35 12(1) 22

45 6 6

30 with ubiquinone 3 6

35 with ubiquinone 1 1 (2) 2040 with ubiquinone 20 (8) 30

45 with ubiquinone 22 (10) 43

included, however, in the analysis of toxicity and antitumor

activity.

Over the range of lovastatin doses administered without

ubiquinone supplementation, cholesterol concentrations de-

dined by 23-43% (nadir, mean ± SE: 143 ± 38 mg/dl; base-

line: 220 ± 56 mg/dl; normal range: 180-230 mg/dl; Fig. 2).

There was no direct correlation between the dose of lovastatin

and the magnitude of the declines. Cholesterol concentrations

rapidly declined during lovastatin administration. The time to

reach the nadir ranged from 7 to 1 1 days after starting therapy

and also appeared to be dose independent. In all patients, the

declines were not sustained once treatment was discontinued

and were completely resolved prior to the initiation of the next

cycle of therapy (Fig. 3).

Serum concentrations of ubiquinone were measured in 24

patients treated at the 25-mg/kg dose level and above. The

declines in this isoprenylated end product of the mevalonate

pathway ranged from 36 to 49% and were independent of the

dose administered (P = 0.72, Spearman’s rank correlation test).

The mean baseline and nadir ubiquinone concentrations mea-

sured before and after 7 days of lovastatin therapy were 0.94 ±

0.47 �.tg/ml and 0.55 ± 0.28 p.g/ml, respectively (Table 3).

Similar to the changes noted in cholesterol concentration, the

declines in ubiquinone were not sustained after stopping lovas-

tatin.

In the second part of the trial, ubiquinone supplementation

was started 7 days before the beginning of lovastatin and con-

tinued until the patient was taken off protocol. The administra-

tion of ubiquinone over 1 week had no effect on the circulating

concentrations of cholesterol. The magnitude of the decline in

cholesterol concentrations following the administration of by-

astatin was not different from those achieved in the first part of

the trial (P = 0.79, Wilcoxon’s rank sum test) and remained

dose independent.

Oral ubiquinone supplementation for a week resulted in a

3-fold increase in serum concentrations (Table 3) from baseline

concentrations of 1 .23 ± 0.78 p.g/ml to 4.58 ± 3.20 �i.g/ml

(mean ± SD, n = 27). Following the administration of lovas-

tatin for 7 days, ubiquinone concentrations decreased on average

by 49% (to 1.88 ± 0.97 p.g/rnl, P = 0.001, Wilcoxon’s signed

rank test) but still exceeded baseline measurements.

Serum HMG-CoA Reductase Inhibitory Activity. The

bioactivity of lovastatin and its metabolites was retrospectively

measured in 40 patients treated at the 4-mg/kg dose level and

above, with lovastatin alone or in combination with ubiquinone.

A total of 149 samples was analyzed. The range of HMG-CoA

reductase bioactivity achieved during the 7-day period of by-

astatin administration was assessed in 1 19 samples. Thirty ad-

ditional samples obtained from patients treated with more than

one cycle of therapy were analyzed to document the presence or

absence of drug activity at various time intervals after the

cessation of lovastatin. Peak bioactivity was reached within 4 h

in all patients and ranged from 0. 10 to 3.92 fiM (mean ± SD,

2.32 ± 1 .27 �.LM). Marked interpatient variability and no direct

relationship to the dose administered were noted (by least-

squares linear regression). Trough activity at the 25-mg/kg dose

level and above averaged 0.28 ± 0.09 p.M. Drug activity in

patients treated with lovastatin and ubiquinone did not differ

from those measured in patients treated with lovastatin alone. In

four patients treated with more than six cycles of therapy, no

drug activity was detected 1 week after completing lovastatin

administration.

Toxicity. Sixty patients (68%) experienced a total of 128

episodes of clinical toxicity. As can be seen from Table 4, the

incidence and severity of toxicity increased markedly once the

25-mg/kg dose level was reached. In the cohort of patients

treated with lovastatin alone (n 32 patients; 104 cycles of

therapy), grade 1 and 2 toxicity encompassed 92% of the epi-

sodes. Gastrointestinal dysfunction was the most commonly

recognized toxicity, comprising 56% of all episodes. The most

severe clinical toxicity was related to the musculoskeletal sys-

tern and manifested primarily as myalgias and muscle weakness.

No musculoskeletal toxicity was recognized at doses <25 mg/

kg/day. At higher doses, however, no direct correlation could be

established between the incidence of myotoxicity and the dose

of lovastatin administered (P = 0.24, Cochran-Armitage test).

In one patient with high-grade glioma treated with lovas-

tatin alone at a dose of 35-mg/kg/day and whose course is



350’

300’

250’

200’

150�

100

-0--- patient 1

. patient 2-- a- patient 3

-“�-,“�--‘..“,‘ patient 4

�: patient 5

0

-U- I

5 10

Cycle Days

15 20 25 30


illC0

C00�C �00iOE

0

0

U)U)

0-CC-)

Fig. 3 Time course of cholesterol decline after bovastatin treatment. Lovastatin induced declines in serum cholesterol concentrations in five

representative patients treated for 7 days at the 25-45-mg/kg/day dose levels (horizontal bar). Notice the recovery in cholesterol concentrations by

the end of each treatment cycle.

Table 3 Serum ubiqu inone concentration s in patients treated wit h lovastatin alone or in combination with ubiquinone

Lovastatin dose

(mg/kg/day) n

Ubiquinone concentration (pg/mi)

Baseline Postubiquinone Postbovastatin

25 5 0.87 ± 0.36 0.49 ± 0.30

30 6 0.89 ± 0.50 0.64 ± 0.4935 10 1.01 ± 0.58 0.53 ± 0.1545 3 0.94 ± 0.60 0.49 ± 0.21

30 with ubiquinone 3 1.31 ± 1.21 3.50 ± 1.34 1.70 ± 0.6035 with ubiquinone 7 0.83 ± 0.16 5.16 ± 4.21 2.03 ± 1.47

40 with ubiquinone 9 1.46 ± 0.57 4.98 ± 2.88 1.93 ± 0.674swithubiquinone 8 1.28 ± 1.1 1 2.83 ± 1.34 1.68 ± 0.91

summarized in Fig. 4, the onset of myopathy occurred after the

sixth treatment cycle, simulating disease progression. The max-

imum severity of this patient’s symptoms was associated with a

low serum concentration of ubiquinone (0.33 pg/ml). Magnetic

resonance imaging of the brain at that time revealed no increase

in tumor volume. The patient’s symptoms resolved almost corn-

pletely 48 h after p.o. supplementation of ubiquinone (60 mg,

p.o., four times daily), at which time serum concentrations of

ubiquinone had increased 9-fold to 3.0 pg/mb. The patient was

subsequently maintained on p.o. ubiquinone and tolerated addi-

tional cycles of lovastatin with no recurrence of symptoms nor

radiological evidence of disease progression for 3 additional

months. Whether intracellular accumulation of lovastatin may

have underlied the occurrence of this toxicity remains specula-

tive at this time. In this patient with advanced brain cancer,

however, the administration of dexamethasone, a synthetic glu-

cocorticoid with known myopathic effects, is a confounding

factor that must be taken into consideration. With the exception

of this case, analysis of the toxicity patterns failed to disclose

any correlation between occurrence and cumulative lovastatin

dose.

Elevations in serum hepatic aminotransferases and creatine

phosphokinase concentrations above the upper limit of the nor-

mal range (alanine aminotransferase, 45 units/liter; aspartate

aminotransferase, 42 units/liter) were the most common labora-

tory toxicities recognized in 23% of the evaluable cycles. Of

note, no elevation of grade 3 severity or higher was noted. The

peak concentrations of these enzymes correlated with the max-

imum intensity of symptoms and occurred between days 7 and

10 in most patients.

To prevent rnyotoxicity and improve the tolerability of

lovastatin, ubiquinone was prophylactically administered to a

second cohort of patients. Fifty-six patients were treated with

bovastatin at doses of 30 mg/kg/day or more and received p.o.

ubiquinone prophylaxis; 27 (98%) patients experienced grade 1

or 2 toxicity and 1 patient experienced grade 3 nausea (2%). One

death occurred secondary to disease progression and was unre-

bated to treatment. Nausea and diarrhea were the most common



Table 4 Toxicity: Major types and frequency per dose level

n Toxicity

Frequency grade

I 2 3 4

4

5

4

3

4

13

8

12

6

30

35

45

0000000

00

000

2

0

2

0000

000000

0000000000000

00

40

45

20

22

10 4

0000

0

0

0

0

000

00


Lovastatin dose(mg/kg/day)

A. Lovastatin alone

2

468

1025

B. Ubiquinone supplementation

30 3

35 11

NauseaDiarrheaAbdominal pain

ConstipationConstipation

MyalgiasMuscle weaknessNausea/vomiting

DiarrheaSkin rashOthersDiarrheaFatigueMyalgias

Muscle weaknessNausea/vomiting

Diarrhea

FatigueOthersMyalgiasMuscle weaknessNausea/vomiting

Diarrhea

Fatigue

Myalgias

TrushMyalgiasMuscle weaknessNausea/vomiting

Diarrhea

OthersMyalgiasMuscle weaknessNausea/vomiting

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gastrointestinal toxicities. The administration of ubiquinone

alone for a week was not associated with toxicity. Ubiquinone

prophylaxis did not decrease the incidence of musculoskeletal

toxicity, but significantly reduced its severity (P = 0.01 1, Co-

chran Armitage test), which was limited to grade 1 ( 15/17, 88%)

and 2 (2/17, 12%). The maximum tolerated dose for the com-

bination regimen was not reached.

Response to Treatment. Evidence of antitumor activity

was documented in one patient with an anaplastic astrocytoma

that was progressing after surgical resection, radiation therapy,

and two cycles of carmustine. The patient was treated with

lovastatin at the 30- and 35-mg/kg/day dose levels and achieved

a minor response (45% reduction in tumor size) that was main-

tamed for 8 months. No activity was documented in the cohort

of patients with hormone-independent prostate cancer.

DISCUSSION

Lovastatin is a prodrug which yields several metabolites

that are responsible for the inhibition of HMG-CoA reductase in

vivo. Incompletely absorbed from the gastrointestinal tract, lo-

vastatin undergoes extensive first-pass metabolism in the liver,



C2 C3 C4 CS C6

* * * + *

25 50 75 100 125 150 175


C

0

aCe

C0-

oE

a,;0

0�

.�

E

a(I)

Time(days)

Fig. 4 Lovastatin-induced myopathy: changes in serum concentrations

of ubiquinone and response to p.o. supplementation. Time course of

bovastatin-induced changes in serum ubiquinone concentrations in a

patient who developed myopathy after several cycles (C) of lovastatin

therapy. Notice the transient inhibitory effect of lovastatin (documented

after cycles 2 and 3) and the rapid increase in ubiquinone concentrations

after p.o. supplementation (horizontal bar).

the main site of its therapeutic activity as a hypocholesterolemic

drug. Several studies have characterized the human pharmaco-

kinetics of lovastatin given at doses not exceeding 2 mg/kg

(21-24). Plasma concentrations of active lovastatin inhibitors

increase linearly following single doses ranging from 60 to 120

mg. Prolonged administration at the maximum recommended

dose (80 mg/day) results in steady-state concentrations of active

lovastatin inhibitors ranging from 0. 15 to 0.3 pM. The pharma-

cological effects of low-dose lovastatin in hypercholesterolemic

patients are better described (24). In these patients, maximum

reduction appears to be dose-related (in the order of 30-40% in

patients treated with 80 mg/day) and occurs within 4-6 weeks

of initiating therapy.

That high doses of lovastatin may be more effective at

inhibiting the mevalonate pathway than currently recommended

doses is suggested by the observation that comparable declines

in cholesterol concentrations occurred more rapidly in our study

(7-10 days) than has been reported with conventional doses. On

the other hand, although marked interpatient variability was

noted, neither the magnitude of the inhibitory effect nor the

circulating drug concentrations correlated directly with the dose

administered. Similarly, the incidence of myotoxicity was inde-

pendent of the dose once 25 mg/kg lovastatin or more were

administered. These findings, which led us to interrupt dose

escalation at the 45-mg/kg level, are possibly accounted for by

saturation of drug absorption at the higher dose levels or by the

short duration of drug administration, which may have pre-

vented larger, dose-dependent effects from taking place.

Several cases point to the depletion of ubiquinone as an

important pathophysiobogical mechanism responsible for lovas-

tatin-induced muscle damage (1 1 ). Our experience establishes

that this type of myopathy can be treated and prevented with p.o.

ubiquinone supplementation. Moreover, we could not identify

an antagonistic effect from ubiquinone in the patients who had

appeared to benefit from lovastatin, which is consistent with

laboratory data (5). Since it did not interfere with the cholester-

ol-lowering effect of lovastatin, ubiquinone may also prove

useful in the management of hypercholesterolemic patients un-

able to tolerate lovastatin’s most serious side effect.

The drug concentrations measured in this Phase I trial

(0. 1-3.9 pM) were comparable to those found to be active

against glioma cells in vitro (0.2-2.0 prvi; Refs. 5 and 7) and

provide a rationale to further study this approach in patients with

high-grade gliomas. Several limiting factors, however, must be

taken into consideration. Although it is not known at present

whether potential antitumor activity would result from the sys-

temic inhibitory effect of lovastatin on the mevalonate pathway

or by the actual drug concentrations in the cerebrospinal fluid or

brain parenchyma, the presence of a relatively intact blood-brain

barrier at the periphery of malignant gliomas represents a for-

midable obstacle to delivering a highly protein-bound drug such

as lovastatin to the actively dividing tumor cells. In addition, the

reversible inhibitory effect of lovastatin and its impact on p0-

tential antitumor activity must not be overlooked. Intermittent

administration of the drug is associated with normalization of

cholesterol and ubiquinone concentrations after treatment is

stopped, and by the absence of detectable lovastatin concentra-

tions as early as I week after drug administration. These find-

ings suggest that a temporary blockade of HMG-CoA reductase

activity is taking place, which would not be expected to result in

sustained biological activity. In this perspective, it is possible

that sustained inhibition of the mevalonate pathway by uninter-

rupted administration of lovastatin may yield improved clinical

results.

In the context of isoprenylation inhibition as an anticancer

approach, peptidic inhibitors of farnesyl transferase, the enzyme

responsible for the isoprenylation of numerous proteins in mam-

malian cells (25), must be mentioned. The therapeutic goal has

been to improve upon the specificity of isoprenylation inhibition

by targeting the ras oncogene in particular. Currently, however,

technical limitations related to the intracellular delivery of these

compounds remain to be solved (26), while their antiprolifera-

tive activity may actually be independent of the ras prenylation

status of the tumor (27).

We conclude that the administration of lovastatin at a dose

of 25 mg/kg daily for 7 consecutive days is well tolerated by

cancer patients, and that high-grade gliomas represent a reason-

able target for Phase II clinical trials. Alternative treatment

schedules aimed at achieving sustained inhibition of mevalonate

synthesis should be investigated.

ACKNOWLEDGMENTSWe thank Natalie McCall and Anne Schleifer for their laboratory

assistance, as well as Nancy Chen for her help in preparing the manu-

script.




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1996;2:483-491. Clin Cancer Res A Thibault, D Samid, A C Tompkins, et al. pathway, in patients with cancer.Phase I study of lovastatin, an inhibitor of the mevalonate

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