Phase I Clinical Trial of Perillyl Alcohol Administered Daily'

Vol. 4, 1159-1164, May 1998 Clinical Cancer Research 1159

Phase I Clinical Trial of Perillyl Alcohol Administered Daily’

Gregory H. Ripple, Michael N. Gould, INTRODUCTION James A. Stewart, Kendra D. Tutsch, Monoterpenes are a class of compounds produced by plants Rhoda Z. Arzoomanian, Dona Alberti, and are found in many commonly consumed fruits and vegeta- bles. The simplest monocyclic monoterpene, limonene, was the Chris Feierabend, Marcia Pomplun, first terpene to be studied as an anticancer agent ( 1). Studies by George Wilding, and Howard H. Bailey2 Elegbede et a!. (2) and Haag et a!. (3) demonstrated that limo- University of Wisconsin Comprehensive Cancer Center, Madison, nene administration could result in the regression of primary rat Wisconsin 53792 mammary carcinomas. These findings and others have led to the clinical testing of limonene in Great Britain (4, 5). Although limonene produced impressive antitumor results with little tox- ABSTRACT icity in rats, the large amount of limonene likely to be required Perillyl alcohol (POH; NSC-641066), a naturally occur- by human subjects to achieve comparable results led to a search ring monoterpene, has shown antitumor and preventive ac- for more potent analogues for potential clinical development. tivity in preclinical studies in rodent models. Drug-related After in vitro screening (6), the naturally occurring hy- activities that have been observed include the induction of droxylated monocyclic monoterpene POH3 (Fig. 1) was chosen apoptosis, cell cycle arrest, the inhibition of posttransla- for in vivo testing. POH has been shown to induce complete tional modification of proteins that are involved in signal regression of greater than 50% of advanced (> 1 cm) chemically transduction, and differential gene regulation. We treated induced rat mammary carcinomas. Dietary POH was markedly 18 patients who had advanced malignancies with POH, more potent (>5X) than limonene in inducing tumor regression. which was given on a continuous three-times-a-day schedule Rats that were chronically fed POH had the same circulating at the following doses: (a) level 1 (Li), 800 mg/m2/dose; (b) metabolites as rats that were fed limonene; however, the levels level 2 (L2), 1600 mglm2/dose; and (c) level 3 (L3), 2400 of these metabolites in plasma were higher in the rats fed POH mg/m2/dose. The main toxicity, which seemed to be dose as compared with those in the rats fed limonene at equivalent related, was gastrointestinal and included nausea and vom- doses (7). Rats given a 2% POH diet for 10 weeks had plasma iting, anorexia, unpleasant taste, satiety, and eructation. levels of terpene metabolites of 0.82 mrvi, whereas those fed a Two heavily pretreated ovarian cancer patients experienced 10% limonene diet had plasma levels of0.27 msi. The observed reversible grade 3 granulocytopema. Grade 1-2 fatigue preclinical antitumor effect of monoterpenes has not been lim- was also noted. The parent drug was not detectable in the ited to mammary carcinoma. Monoterpenes have also been plasma. The mean peak plasma levels of the two main shown to inhibit colon, pancreatic, stomach, lung, skin, and liver metabolites on days 1 and 29 were 175 and 139 .aM (Li), 472 cancers (8-14) in rodent models. and 31i LM (L2), and 456 and 257 iM (L3) for perillic acid The mechanism of action of the terpenes is still under (PA) and 7.1 and 9.8 iM (Li), 34.2 and 34.0 M (L2), and study, but several drug-related activities have been documented: 26.2 and 23.4 piM (L3) for dihydroperillic acid (DHPA). Peak (a) cellular effects such as a G1 block (15) and the induction of levels were noted 2-3 h postingestion for PA and 3-5 h apoptosis ( 14); (b) biochemical effects such as the inhibition of postingestion for DHPA. Metabolite half-lives measured posttranslational modification of small G proteins involved in about 2 h for each. POH, PA, and DHPA were detectable in signal transduction. Limonene and POH have been shown to the urine of all patients at L3. About 9% of the total dose inhibit isoprenylation of a class of 21-26-kDa proteins, includ- first 24 h. was recovered in the The majority was recovered ing p21RAS and other small GTP-binding proteins, in a dose- as PA; less than 1 % was recovered as POH. Disease stabi- dependent manner at a point in the mcvalonic acid pathway lization for 6 months was seen, although no objective distal to 3-hydroxy-3-methylglutaryl-CoA reductase (16); and tumor responses were noted. Further study of POH contin- (c) differential gene regulation including overexpression of the ues with a more frequent dosing schedule. M6P/IGF-II and TGF-3 type II receptor genes. Control and monoterpene-treated mammary carcinomas were examined by immunohistochemical methods and demonstrated dramatic in- creases in the levels of both the M6PIIGF-II receptor and TGF-

Received 10/7/97; revised 1/29/98; accepted 2/4/98. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. 3 The abbreviations used are: POH, perillyl alcohol; PA, pcrillic acid;

I Supported by NIH Grants UO1CA62591, R37-CA38128, and RR03186 DHPA, dihydroperillic acid; IGF-II, insulin-like growth factor type II; and CaP Cure. M6PIIGF-II, mannosc-6-phosphate/IGF-ll; TGF43, transforming growth

2 To whom requests for reprints should be addressed, at University of factor 3; Li. level 1; L2, level 2; L3, level 3; TID, three times a day; Wisconsin Comprehensive Cancer Center, 600 Highland Avenue, Room Cmax, peak plasma concentration; AUC, area under the concentration- K6/336, Madison, WI 53792. Phone: (608) 263-8600; Fax: (608) 263- time curve; tmax, time to peak concentration: t112, half-life; DLT. dose- 8613. limiting toxicity; NC!, National Cancer Institute; GI, gastrointestinal.

CH2OH Table 1 Patient characteristics

No. of patients entered 18 No. of patients evaluable 16 Mean age (range) (yr) 58.6 (23-82) Male:female 8:10 Performance status (ECOG)” 0 10 1 6 2 2 Tumor type Prostate 4 H3C CH2 Ovarian 3 Sarcoma 3 Fig. 1 Chemical structure of POH (NSC-641066: CAS-536-59-4: Renal cell” 3 Ref. 19). Breast 2 Hepatocellular 1 Chronic myelogenous leukemia I Chronic lymphocytic leukemia” 1 Adenocarcinoma, unknown primary 1 in treated tumors compared with those of the controls. Consist- Prior therapy ent with the potential importance of the M6P/IGF-II receptor in Chemotherapy 14 POH-induced tumor regression, responding tumors had in- Radiation therapy 9 creased M6PIIGF-II receptor levels when compared with those Hormonal therapy 6 Biologic response modifiers 4 of treated nonresponding tumors (17). Similarly, liver tumors from POH-treated animals showed increased mRNA levels for ‘I ECOG, Eastern Cooperative Oncology Group. 1 One patient had two malignancies, renal cell carcinoma and the M6PIIGF-II receptor and for the TGF-3 type I, II, and III chronic lymphocytic leukemia. receptors compared with those of untreated animals (14). Preclinical toxicity testing performed by the NCI in rats and dogs showed dose-related GI and renal toxicity. The toxicity of large single doses consisted of emesis and diarrhea. His- eligible. Patients with an Eastern Cooperative Oncology Group topathological studies revealed forestomach epithelial hypcrpla- performance status of >2, a life expectancy of < 12 weeks, or sia, necrosis and/or erosion, and renal tubular degeneration. brain metastases were ineligible. Patients must not have re- Twenty-eight-day toxicity studies of orally administered POH ceived any hormonal or immunological therapy within 2 weeks have had nephrotoxicity (rising blood urea nitrogen levels and or cytotoxic chemotherapy or radiation therapy within 4 weeks renal lesions) as a DLT (18, 19). (6 weeks for nitrosoureas and mitomycin C), before receiving Plasma levels of the major POH metabolites, PA and the drug. Patients were not permitted to take cholesterol-lower- DHPA, were measured in both the dog and rat toxicity studies ing agents, vitamins, or other antioxidants while on this study. mentioned above. In dogs, the mean Cmax Of PA occurred at 2 h. Patient characteristics are listed in Table 1. AUC profiles were very similar on days 14 and 28, indicating a Drug Formulation. POH was formulated in soft gelatin lack of PA accumulation and consistent absorption kinetics and capsules containing 250 mg of POH and 250 mg of soybean oil. metabolism with repeated dosing. Plasma DHPA levels were Capsules were supplied by the Investigational Drug Branch, considerably lower than those of PA (mean Cmax and AUC of Division of Cancer Treatment, Diagnosis and Centers, NCI DHPA, 3.5 and 4.4% of the respective values for PA). In the rat (Bethesda, MD). study, the ratio of plasma DHPA:PA was markedly higher than Drug Administration and Dose Escalation. POH was that observed in dogs (Cmax and AUC of DHPA were 35-65% administered orally on a continuous TID basis. Patients re- and 40-81 % of the respective values for PA). This species mained on the drug until evidence of progressive disease, the difference has been observed in previous studies with POH. development of irreversible or life-threatening toxicity, refusal As a result of the above preclinical work, a Phase I dose- by the patient to continue therapy, or other changes in a patient’s escalation trial was undertaken administering POH on a contin- condition rendering him/her unacceptable for further therapy in uous TID schedule to assess for pharmacokinetic and toxicity the judgment of the investigator. data. The dose escalation scheme is shown in Table 2 and was carried out according to a standard Phase I design. The starting PATIENTS AND METHODS dose was 2 x 0.1 of the lethal dose in 10% of the subjects, as Patient Selection. Individuals with advanced malig- determined from the 28-day dog studies. A minimum of three nancy for whom no effective standard therapy was available patients were treated and evaluated for 4 weeks at each dose who gave informed consent according to Food and Drug Ad- level. DLT was defined as any toxicity grade 3, according to ministration and institutional guidelines and had adequate bone the NCI common toxicity criteria, that occurred within the first marrow function (WBC count 4,000/mm3, platelets 4 weeks of the study; grade 2 vomiting of 3 days’ duration, 100,000/mm3, and absolute neutrophil count 1,500), renal grade 2 diarrhea of 3 days’ duration, and grade 2 creati- function (blood urea nitrogen 30 mg%, creatinine 1.5 nine were also considered DLTs. Hematological and nonhema- mg/dl), and hepatic function (bilirubin 1 .5 mg/dl, aspartate tological parameters were monitored weekly during course 1 aminotransferase 2.0 times upper limit of normal) were and every 2 weeks thereafter.

Table 2 Dosc-escal ation scheme” and 3rd months of therapy, respectively. Both had received three

No. of No. of patients No. of prior chemotherapy regimens, and one had also received radiation Dose patients on therapy for evaluable therapy to the abdomen and pelvis. In both patients, the toxicity Level (mg/m2/dosc) entered 3 months courses resolved within 1-2 weeks after stopping the drug. An additional Ll 800 4 2 11 patient with renal cell carcinoma and chronic lymphocytic leuke- L2 1600 7 4 22 mia developed grade 3 granulocytopenia that was thought to be L3 2400 7 3 26 related to disease progression rather than to drug toxicity. “ The dose, the number of patients at each level (the total and the Other Toxicities. Fatigue was also noted but was gener- number of patients on therapy for 3 months or more), and the total ally mild (grade 1-2). No evidence of hepatic, renal, or neuro- number of evaluable courses at each level are shown. logical toxicity was observed. Per our original protocol. only one episode of grade 3 nausea met the criteria for DLT. Other toxicities either did not occur within the first 4 weeks of treatment or had a duration of <3 days, e.g. , grade 2 nausea or Pharmacokinetics Sampling. During course I , hepa- vomiting. rinized blood samples were collected to measure POH and its Pharmacokinetics. The parent drug was not detectable metabolites at baseline (assay blank) and at 0.5, 1, 1.5, 2, 3, 4, in the plasma. Tables 4 and S summarize the day I and day 29 6, 8, 23, and 25 h on day 1. Patients took only one dose of drug single-dose pharmacokinetic parameters for the two main me- on day 1 . On day 1 of course 2, samples were drawn at 0.5, 1, tabolites, PA and DHPA. Peak plasma levels occurred approx- 1.5, 2, 3, 4, and 6 h after ingestion of the morning dose. In imately 1.5-3.5 h postingestion for PA and 3-5 h postingestion addition, trough samples were drawn on days 3-5 of course 1 for DHPA. The t11-, for each metabolite was approximately 2 h. and weekly during courses 1 and 2. Urine samples were col- As in the dog studies, the DHPA levels in plasma were consid- lected from patients at L3. A 24-h collection was performed on crably lower than the PA levels. Metabolite peak levels and 6-h day 1, and a 6-h collection was performed on day 29. AUCs for both PA and DHPA on day 1 showed a significant Analytical Methods. POH, PA, and DHPA were meas- increase from Ll to L2. For example, the mean PA peak levels ured in plasma and urine using the gas chromatographic method of on day 1 at Ll and L2 were 210.7 and 526.0 p.M. respectively Phillips et a!. (20). Standards for the assay were provided by the (n 4 and n = 7; P = 0.021). The metabolite peak levels and Drug Synthesis and Chemistry Branch, Developmental Therapeu- AUCs at day 29 were not statistically different between Ll and tics Program, Division of Cancer Treatment, Diagnosis and Cen- L2 with the exception of the DHPA peak value, which was ters, NCI. For each single-dose concentration-time data set, phar- higher at L2 than at Ll (P 0.036). There were no significant macokinetic parameters for PA and DHPA were determined by differences between metabolite peak concentrations or AUCs on noncompartmental methods (21). The AUC for 0-6 h was deter- either day 1 or day 29 between L2 and L3. PA and DHPA peak mined by using the linear trapezoidal rule. The Cm and tmax were concentrations and AUC values seemed to decrease from day 1 determined by directly inspecting the data. The single-dose t112 was to day 29, but these differences did not reach statistical signif- determined by log-linear regression on the terminal portion of the icance. Two patients at L3 (2400 mglm2/dose) required dose concentration-time curve. PKAnalyst (MicroMath Scientific Soft- reductions to L2 (1600 mg/m2/dosc) because of toxicity and ware, Salt Lake City, UT) and Sigma Stat (Jandel Scientific, San have pharmacokinetic data at both levels. Metabolite levels Rafael, CA) were used to determine the AUC and to perform the seemed to be higher at L2 than at L3. For the first patient, the linear regression. PA Cmax at L3 on days 1 and 29, respectively, was 163.9 and

155.6 p.M. The PA Cmax on day 41 at L2 was 497.8 p.M. For

RESULTS DHPA, the corresponding values at L3 were 24.6 and 21 .2 p.M Patients. A total of 18 patients were entered on this trial versus 42.6 p.M at L2. For the second patient, on day 1 at L3, the on the TID dosing schedule and received a total of 59 evaluable Cmax for PA and DHPA were 143.3 and 6.15 p.M. respectively. courses. Two patients were not evaluable for toxicity. One The corresponding values on day 16 at L2 were 300.8 and 9.72 p.M. patient at Li died on day 13 from progressive disease (which Metabolite trough levels were measured weekly and were general]y was documented radiologically). A second patient was noneva- undetectable, although in some cases, levels of < 10 p.M were seen. luable at L2, because he was taking other medications that were There was no evidence of metabolite accumulation. No correlation not permitted. Course 3 of another patient at L2 was nonevalu- was seen between metabolite levels and toxicity. able, because scheduled laboratory tests were missing. Most Assays of urine samples were performed for all patients at patients had received prior chemotherapy or radiation treatment. L3. These data are summarized in Table 6. POH, PA, and GI Toxicity. Table 3 summarizes the toxicity data. The DHPA were detectable in all patients at L3. Approximately 9% most common toxicity seen was GI. Two patients at L3 expe- of the total dose was recovered in the first 24 h. The majority rienced grade 3 nausea and vomiting. Three patients, two at L3 was recovered as PA, with less than 1% recovered as POH. and one at L2, experienced grade 2 nausea and vomiting. One Activity. No objective tumor responses were seen on the patient at L3 experienced grade 2 diarrhea. Patients also fre- TID schedule. One patient with ovarian cancer entered at L3 quently complained of other GI symptoms including anorexia, showed an initial decline in her CA 125 level. However, during satiety, eructation, and unpleasant taste. course 3, she developed reversible grade 3 granulocytopenia Myelosuppression. Myelosuppression was observed in requiring a dose reduction. At L2, her CA 125 began to slowly three patients. Two ovarian cancer patients, one at L2 and one at increase. She returned to L3 but was taken off the study with L3, experienced reversible grade 3 neutropema during their 2nd progressive disease after 7 months of therapy. Two other pa-

Table 3 Toxicity”

No. of courses with grade of toxicity

GI (includes nausea, vomiting, ANC” diarrhea, other) Fatigue Total no. of Level courses 1 2 3 4 1 2 3 4 1 2 3 4

LI 11 0 0 0 0 1 0 0 0 2 1 0 0 L2 22 2 1 0 1 19 I 0 0 7 0 0 0 L3 26 8 2 1 0 13 2 2 0 6 2 0 0

a At each dose level, the number of courses associated with each particular grade of toxicity is shown. b ANC, absolute neutrophil count.

Table 4 Single-dose metabolite pharmacokinetic parameters for PA”

Dose level Cmax (p.M) tmax (h) 6h AUC (p.M X h) p11, (h)

Li Day I 175 ± 88 1.4 ± 0.6 374 ± 96.4 2.7 ± 1.6 Day 29 139 ± 88 2.0 ± 1.7 368 ± 64.7 6.4 ± 4.9 L2 Day 1 472 ± 199 3.0 ± 1.6 1369 ± 663 1.0 ± 0.3 Day 29 31 1 ± 152 2.1 ± 0.5 665 ± 320 1.6 ± 1.0 L3 Day 1 456 ± 348 2.9 ± 1.7 1425 ± 1369 1.9 ± 2.2 Day 29 257 ± 224 3.5 ± 1.8 731 ± 852 2.5 ± 3.2

a Values are shown for days 1 and 29 at each dose level. Values represent means ± SD.

tients with ovarian cancer were treated in the study but were preclinical work, a Phase I dose-escalation study was begun to removed from the study at their request after 2 and 3 months. determine the toxicity, pharmacokinetic profile, and Phase II dose Three patients with hormone-refractory prostate cancer (one at of POH when given to humans on a continuous liD schedule. Li and two at L2) received POH for 5, 6, and 6 months with stable POH was generally well tolerated on this schedule. The disease before being removed because of disease progression. All most frequent toxicity was GI, with symptoms consisting of of the patients noted above had either a tumor marker or radiolog- nausea, cructation, unpleasant taste, and early satiety. No sig- ical evidence of disease progression in the months preceding study nificant problems with diarrhea were noted. The incidence of GI entry. One patient with chronic myelogenous leukemia in the toxicity of any grade was clearly greater at L2 and L3 than at Li. chronic phase who had relapsed after bone marrow transplantation In addition, no episodes of GI toxicity grade 2 were seen at was treated at L3 with control of peripheral blood counts for 6 Li , whereas one episode was noted at L2, and four episodes months. She had previously required hydroxyurea for the control of were noted at L3, supporting a potential relationship to the dose. peripheral blood counts. This was discontinued according to the Several possibilities exist for this observed toxicity. The drug is protocol before beginning treatment with POH. formulated in a gelatin capsule that contains 250 mg of soybean oil and 250 mg of POH per capsule. Delayed gastric emptying DISCUSSION and decreased lower esophageal sphincter pressure have been The ability to treat advanced malignancies has not improved observed after the intake of meals high in fat content. It is appreciably in recent years. Classic cytotoxic DNA-damaging unclear whether the amount of fat intake associated with POH agents have little curative potential in this setting, and remissions intake (up to 15 g/day at L3) is sufficient to cause these effects. arc rarely durable. Given these limitations, emphasis has been As a hydrocarbon, POH could potentially cause direct-contact placed on the development of new therapeutic agents with novel gastric irritation. In addition, peppermint oil has been shown to mechanisms of action. The monoterpenes, specifically POH, are decrease lower esophageal sphincter pressure and cause esoph- examples of such agents. Predinical testing in animal models has ageal reflux through effects on calcium channels (22). Menthol, shown activity in a number of different tumor types including also a monoterpene, is thought to be the cause of this activity. It primary mammary, pancreatic, stomach, lung, skin, and liver can- is possible, given its structural similarity to menthol, that POH cers (8-14). The mechanism(s) of action is still under study, but induces similar effects, although this has not been specifically possibilities include cellular effects such as an early G1 block and investigated. The number of pills taken ( 1 5-20 pills/dose at L3) the induction of apoptosis and biochemical effects such as the could also have contributed to the GI toxicity seen in this study. inhibition of posttranslational modification of proteins involved in Grade 1-2 fatigue was also noted and seemed to be drug signal transduction and differential gene regulation (14-17). Pre- related, because at least three patients noted an improvement in clinical data on monoterpenes imply that they may have a tumori- these symptoms after drug discontinuation. Although the fatigue static effect, and their plasma t1, is such that multiple daily doses was considered to be mild by the usual toxicity criteria, it was are required to ensure steady-state plasma levels. Based on this severe enough to lead one patient to withdraw from the study.

Table 5 Single-dose metabolite pharmacokinetic parameters for DHPA”

Dose level Crnax (p.M) trnax (h) 6-h AUC (p.M X h) 1112 (h) Li Day 1 7.1 ± 1.6 3.0 ± 2.0 35.6 ± 16.8 3.3 ± 2.2 Day 29 9.8 ± 5.6 3.3 ± 2.3 27.5 ± 1.8 1.2 ± 0.8 L2 Day 1 34.2 ± 12.9 5.0 ± 2.4 123 ± 55 2.2 ± 0.7 Day 29 34.0 ± 23.0 3.2 ± 0.5 101 ± 76 2.0 ± 0.8 L3 Day 1 26.2 ± 17.5 5.1 ± 1.6 108 ± 84 2.1 ± 1.6

Day 29 23.4 ± 19.9 3.1 ± 2.0 86 ± 68 NAb

“ Values are shown for days 1 and 29 at each dose level. Values represent means ± SD. b NA, no data or not enough data.

Table 6 Urinary drug and metabolite levels”

% Total dose % Recovered % Recovered % Recovered Day recovered as POH as PA as DHPA

1 (0-8 h) 7.2 ± 4.0 <1 89.2 10 1 (8-24 h) 1.9 ± 1.7 <0.5 76.2 23.4 29 (0-6 h) 8.4 ± 4.5 0.5 91.0 8.3

‘I Values represent the means for patients at L3 only.

Unexpectedly, two patients experienced significant drug- L2 and L3 on day 1 was 472 and 456 p.M, respectively. These related myclosuppression (grade 3 granulocytopenia), one at levels are within the range of values seen on random samples L2 and one at L3. In both cases, the toxicity occurred after more obtained in rat studies at doses shown to be effective at inducing than 4 weeks on study and resolved within 1-2 weeks of tumor regression (390-480 p.M; Ref. 7). For DHPA, on day 1,

stopping the drug. Both patients were heavily pretreated ovarian the Cmax values at L2 and L3 (34.2 and 26.2 p.M. respectively) cancer patients. One of these two patients developed grade 3 were somewhat lower than the random levels seen in the rat granulocytopenia after 10 weeks of treatment at L3. She subse- study (110-230 p.M). As shown in Tables 3 and 4, the plasma quently underwent a dose reduction from L3 to L2 and was levels (mean Cmax and 6-h AUC) of the two main metabolites treated for 12 weeks without a recurrence of the toxicity. Inter- were very similar at L2 and L3 and, particularly at L3, seemed estingly, despite the lower dosage, the metabolite levels were to be lower on day 29 than on day 1. It is not known whether equal to or greater than those observed during treatment at the POH absorption occurs by diffusion or is carrier mediated. If it higher level. She was then retreated at L3 for an additional 8 is carrier mediated, it is possible that saturation of the trans- weeks without a recurrence of the toxicity before being removed porter could account for this apparent ceiling effect of metabo- from the study because of progressive disease. No other signif- lite levels with increasing drug dosage. The soybean oil (com- icant toxicities (including hepatic, renal, and neurological tox- posed primarily of long-chain polyunsaturated fatty acids) may icity) thought to be related to the drug were noted. also interfere with POH absorption, but this seems unlikely. Significantly, however, four patients were removed from Alternatively, monoterpenes have been shown to up-regulate the study at their request. One of these seemed to have slowly phase 1 and 2 hepatic detoxification enzymes (23, 24), and the progressive disease that, although not meeting the criteria for induction of metabolism provides another possible explanation. progressive disease, was thought to indicate a lack of benefit The only patient at L3 without a decrease in metabolite concentra- from the study drug. In the other three patients, the reason for tion from day i-29 was a patient who was receiving Tegretol discontinuing the study was related to persistent low-grade (carbamezepine), an agent well-known to induce phase 1 or 2 (grade 1-2) toxicities, primarily GI toxicity and fatigue. Al- enzymes. Significant interpatient variability in metabolite levels though these toxicities arc considered mild by traditional stand- was also observed. Possible explanations for this include a variation ards, they clearly have the potential to affect compliance with in absorption secondary to food intake or the use of histamine 2 the repeated administration of a p.o. agent and must be consid- receptor antagonists and interpatient differences in the levels of ered in the clinical development of such agents. As noted in detoxification enzymes involved in POH metabolism. No clear “Results,” only one of the toxicities observed met the study relationship of drug toxicity to metabolite levels was seen. The criteria for DLT. Therefore, further enrollment on this schedule metabolite half-lives were relatively short (2-3 h), and there was no was permissible. However, given the chronic low-grade toxici- evidence of drug or metabolite accumulation on the TID schedule. ties noted, this did not seem to be practical, and the investigators Evidence of antitumor activity was limited to a decline in the chose instead to explore alternative dosing schedules. CA 125 level in a patient with ovarian cancer and to disease Pharmacokinetic analysis showed the two main metabolites stabilization for up to 6 months in several other patients. Given the in humans to be PA and DHPA, which are present in a ratio possible mechanism(s) of action of POH, it is possible that a similar to that observed in dog studies. The mean Cmax of PA at clinically beneficial effect will manifest itself only as a static state

or as disease stabilization in some patients. Therefore, traditional 9. Burke, Y. D., Stark, M. J., Roach, S. L., Sen, S. E., and Crowell, P. L. surrogate end points used to assess the activity of cytotoxic agents Inhibition of pancreatic cancer growth by the dietary isoprenoids fame- so! and geraniol. Lipids, 32: 151-156, 1997. such as tumor shrinkage may not be appropriate in this setting. This 10. Wattenberg, L. W., and Coccia, J. B. Inhibition of 4-(mcthylnitro- issue should be considered in the design of future Phase II and ifi soamino)-1-(3-pyridyl)-l-butanone carcinogenesis in mice by D-limo- studies of this agent, in which freedom from failure and overall nene and citrus fruit oils. Carcinogenesis (Lond.), 12: 1 15-1 17, 1991. survival may be the most appropriate end points. 11. Wattenberg, L. W., Sparnins, V. L., and Barany, G. Inhibition of POH and other monoterpenes have been shown to modify N-nitrosodiethylamine carcinogenesis in mice by naturally occurring orga- growth factors and their receptors. Increased levels of the M6P/ nosulfur compounds and monoterpenes. Cancer Res., 49: 2689-2692, IGF-II receptor have been seen in POH-treated, regressing tu- 1989. mors. This receptor degrades IGF-II and facilitates the activa- 12. Van Duuren, B. L., and Goldschmidt, B. M. Cocarcinogenic and tion of TGF-3, which has previously been shown to be an tumor-promoting agents in tobacco carcinogenesis. J. Natl. Cancer Inst., 56: 1237-1242, 1976. inhibitor of both normal and malignant cell growth (17, 25, 26). 13. Crowell, P. L., and Gould, M. N. Chemoprevention and therapy of Active TGF-3 can up-regulate its receptors. These activities cancer by D-limoncne. Crit. Rev. Oncog., 5: 1-22, 1994. may be important mechanistically in the antitumor activity of 14. Mills, J. J., Chari, R. S., Boyer, I. J., Gould, M. N., and Jirtle, R. L. POH and other monoterpenes. Although plasma TGF-3 levels Induction of apoptosis in liver tumors by the monoterpene perillyl are not available for patients treated on this schedule, we do plan alcohol. Cancer Res., 55: 979-983, 1995. to investigate this further in patients being treated on other 15. Shi, W., and Gould, M. N. The anticancer monoterpene perillyl schedules. In addition, it would be interesting to examine patient alcohol causes a decrease in cellular cyclin Dl levels contributing to an tumor samples for the expression of the M6PIIGF-II receptor early G1 arrest in mammary cells. Proc. Am. Assoc. Cancer Res., 38: 263, 1997. before and, when possible, during treatment with POH to see 16. Crowd!, P. L., Chang, R. R., Ren, Z., Elson, C. E., and Gould, whether this correlates with the response to treatment. M. N. Selective inhibition of isoprenylation of 21-26 kDa proteins by The presumed mechanism(s) of action of the monoterpenes the anticarcinogen D-limonene and its metabolites. J. Biol. Chem., 266: implies that the optimum schedule of administration would result in 17679-17685, 1994. an almost continuously circulating drug (or metabolites). Because 17. Jirtle, R. L., Haag, J. D., Ariazi, E. A., and Gould, M. N. Increased single, larger doses do not seem to provide an advantage in terms levels of M6PIIGF-II receptor and TGF-31 levels during monoterpene- of metabolite levels (AUC) and may be associated with increased induced regression of mammary tumors. Cancer Res., 53: 3849-3852, toxicity (particularly GI toxicity), further study of POH at the 1993. University of Wisconsin is using a more frequent dosing schedule. 18. Evans, E., Arneson, D., Kovatch, R., Supko, J., Morton, T., Siemann, L., Cannon, J., Tomaszewski, J. And Smith, A. 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G H Ripple, M N Gould, J A Stewart, et al.

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