|
Advertisement |
|
|
||
 |
|
|||||
|
|||||
|
 |
||||||
|
||||||
|
||||||
|
Journal of Clinical Oncology, Vol 24, No 25 (September 1), 2006: pp. 4092-4099 © 2006 American Society of Clinical Oncology. DOI: 10.1200/JCO.2005.05.3447 Phase I Dose Escalation and Pharmacokinetic Study of Enzastaurin, an Oral Protein Kinase C Beta Inhibitor, in Patients With Advanced Cancer
From the Division of Medical Oncology, Kimmel Cancer Center at Johns Hopkins, Baltimore, MD; Eli Lilly and Company, Indianapolis, IN; and The University of Texas M.D. Anderson Cancer Center, Houston, TX. Address reprint requests to Roy S. Herbst, MD, PhD, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Blvd, Unit 432, Houston, TX 77030; e-mail: rherbst{at}mdanderson.org
Purpose This phase I study was conducted to determine the recommended dose of enzastaurin, an oral protein kinase C beta (PKCβ) inhibitor, for phase II trials. Secondary objectives were maximum-tolerated dose (MTD), pharmacokinetics (PK), toxicity, and response. Patients and Methods Patients at least 18 years of age with advanced cancer and an Eastern Cooperative Oncology Group performance status of 0 or 1 lower received enzastaurin orally once daily at a starting dose of 20 mg. Dose escalation proceeded using a modified Simon design. Results All 47 patients enrolled (mean age, 58 years) received at least one dose of enzastaurin, with a median of two cycles (range, one to 17 cycles). Prevalent malignancies were lung (n = 10) and head and neck cancers (n = 9). Although no MTD was identified up to 700 mg/d, 525 mg was chosen as the recommended dose, and 12 additional patients were accrued at that level. Three dose-limiting toxicities (QTc changes) occurred: one at the 700-mg dose (patient discontinued), and two in the expansion cohort at the 525-mg dose. Total analytes (enzastaurin and its metabolites) exposure increased with increasing doses up to 240 mg, and appeared to plateau at 525 and 700 mg. Grade 1 chromaturia, fatigue, and other GI toxicities were the most common, while no clinically significant grade 3/4 toxicities occurred. Two deaths, unrelated to enzastaurin, occurred. Twenty-one patients (45%) achieved stable disease (SD) for two to 16 cycles. Conclusion On the basis of plasma exposures and safety data, enzastaurin 525 mg once daily is the recommended phase II dose. Enzastaurin is well tolerated up to 700 mg/d. Evidence of early activity was seen with significant stable disease.
The protein kinase C (PKC) family of isoenzymes, which belongs to the widely expressed group of serine/threonine kinases and is involved in key cellular processes,1,2 is a possible target for antitumor therapy.3-5 Activation of PKC is implicated in tumor-induced angiogenesis and the regulation of key processes that lead to tumor growth and survival.6 PKC overexpression and increased activity has been linked to many cancers including colon,7 renal cell,8 hepatocellular,9 non–small-cell lung,10 and prostate cancers.11 In patients with fatal/refractory diffuse large B-cell lymphoma, PKC beta (PKCβ) is one of the most prominently overexpressed genes and is linked to poor prognosis.12 PKC is stimulated on vascular endothelial growth factor (VEGF) receptor activation13-15 and is an important mediator of VEGF, the most potent angiogenic factor in the highly vascular brain, kidney, bladder, and ovarian tumors.13 Recent evidence also suggests a link between PKC and the main pathway responsible for apoptosis regulation, the PI3K/AKT pathway (Fig 1). 16,17
Enzastaurin HCl (LY317615), an acyclic bisindolylmaleimide, is a potent selective serine/threonine kinase inhibitor. Initially developed as an adenosine triphosphatase (ATP) -competitive selective inhibitor of PKCβ,18 enzastaurin also targets the PI3K/AKT pathway and inhibits GSK3 phosphorylation.19 In vitro preclinical assays show approximately 95% plasma protein binding and an inhibitory concentration (IC90) of 70 nmol/L for PKCβ (Upstate kinase profiler data). Enzastaurin is metabolized primarily by cytochrome P450 3A (CYP3A) to form a desmethylenepyrimidyl metabolite (LY326020) and a desmethyl metabolite (LY485912), which are comparably potent against PKCβ, with IC50s of approximately 5 nmol/L (J. Graff, personal communication, February 2006). LY326020 is also a substrate for CYP3A (B. Ring, personal communication, April 2006). Enzastaurin induced apoptosis and decreased proliferation of various cancer cell lines,19 and decreased VEGF expression and microvessel density in human tumor xenografts.20 In rat corneal micropocket assay, 30 mg/kg enzastaurin (free drug = 100 nmol/L) suppressed the growth of new blood vessels.21 In animal models, enzastaurin showed antitumor and antiangiogenic activity in various malignancies, including non–small-cell lung, colon, renal cell, and hepatocellular carcinomas.22,23 Enzastaurin also augmented the delay in growth of non–small-cell lung cancer produced by cytotoxic agents.24 Preclinical toxicology studies showed that enzastaurin was generally well tolerated in rats and dogs. In some dogs administered high daily doses of enzastaurin, observations of prolonged QT and QTc values occurred after 5 weeks of dosing, and cataracts were seen after 13 weeks of dosing. These findings were noted at exposures that were higher than those expected to occur in most patients (N. Horton, personal communication, February 2006). On the basis of promising preclinical activity and encouraging safety data, we conducted a phase I study to determine the recommended phase II dose of enzastaurin for patients with advanced cancer. Secondary objectives were to determine the maximum-tolerated dose (MTD) and pharmacokinetic properties of enzastaurin, and to assess toxicity and antitumor activity.
Inclusion and Exclusion Criteria Patient eligibility criteria included histologic or cytologic diagnosis with clinical or radiologic evidence of locally advanced or metastatic malignancies; age of at least 18 years; predicted life expectancy of at least 12 weeks; Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1; and adequate hematopoeitic, hepatic, and renal function (absolute neutrophil count  1.5 x 109/L, platelets 100 x 109/L, hemoglobin 9 g/dL, bilirubin within 1.3x upper limit of normal [ULN], transaminases  2.5 x ULN, and creatinine < 1.5 x ULN). Patients must have discontinued all cancer therapies at least 4 weeks before study entry, except for luteinizing hormone–releasing hormone analog therapy for men with hormone-refractory prostate cancer. Exclusion criteria included inability to swallow capsules; symptomatic CNS metastasis; current hematologic malignancies or a serious concomitant systemic disorder; baseline ECG abnormalities including prolonged QTc interval (> 450 msecs for males or > 470 msecs for females); or uncorrected electrolyte disorders. Written informed consent was obtained according to federal and local institutional guidelines. The study was conducted in accordance with the Declaration of Helsinki and the applicable guidelines on good clinical practice.
Study Design
Each cohort started with three patients. If one patient experienced a DLT, three additional patients were enrolled at that dose level; if two or more of the six patients ( The MTD was defined as one dose level below that at which 33% of patients within a cohort experienced DLT. Patients who withdrew before completing one cycle without reporting a DLT were not evaluated for MTD determination and dose escalation. Nonassessable patients were replaced to ensure that three to six patients completed one cycle at each dose level, unless accrual stopped as a result of DLT. Determination of the recommended phase II dose was based on data for toxicity and pharmacokinetics, with the intent of exceeding effective plasma exposures (based on preclinical data). An additional 12 patients were then treated at that dose. If those 12 patients experienced less toxicity than expected, the dose was escalated in subsequent patients to determine an alternate phase II dose.
Treatment Plan
Baseline and Treatment Assessments Poststudy evaluation conducted 30 days after the last dose included performance status evaluation, tumor measurements, tumor markers, and imaging studies. All patients who received at least one enzastaurin dose were evaluated for safety and efficacy. (A formal efficacy analysis was not planned.) Response was assessed by Response Evaluation Criteria in Solid Tumors (RECIST)27 every other cycle, and was confirmed at least 4 weeks after the initial observation.
Pharmacokinetics
Flow Cytometry
Patient Characteristics From February 2001 to July 2003, 47 patients were enrolled at two study centers (Table 1). The most common cancers were lung and head and neck cancers. Of the 47 patients, 42 had at least one prior therapy. All 47 patients received at least one enzastaurin dose, with a median of two cycles (range, one to 17).
Recommended Dose and Toxicity Table 2 lists the DLTs and grade 1 to 2 nonlaboratory toxicities possibly related to enzastaurin that affected patient accrual and dosage escalation, respectively. The dosing began at 20 mg/d and was escalated to 700 mg/d. There were 17 protocol-defined intrapatient dose escalations in a total of eight patients. An MTD was not identified because DLTs were not observed in 33% of patients in any cohort. However, on the basis of the pharmacokinetic and safety data, 525 mg was identified as the recommended phase II dose. Therefore, 12 additional patients were accrued in this cohort. Three DLTs were reported: one patient at the 700-mg dose level was initially diagnosed with a DLT of QTc interval prolongation by more than 50 msecs (later amended to ST-T wave changes), and two patients in the expansion cohort at the 525-mg dose level had QTc interval prolongation by more than 50 msecs over baseline (which did not require treatment or discontinuation).
Table 3 lists the NCI-CTC clinically relevant toxicities observed in at least two patients. Other toxicities, including anorexia, arthritis, bruising, sensory neuropathy, dyspnea, edema, and sense of smell, were reported in one patient each and were mild in nature ( grade 2).
One QTc interval prolongation (grade 1) and arthralgia (grade 2), in the same patient, resulted in three drug-related dose omissions. There were eight dose reductions (resulting from either patient error or adverse event) and one dose delay, which accompanied a reduction for moderate arthralgia. ST-T wave changes at 700 mg (initially diagnosed as QTc prolongation) led to one discontinuation. Two deaths were reported, both unrelated to enzastaurin. One patient died as a result of disease progression within 30 days of discontinuation, and another patient died of myocardial infarction. At the time of autopsy, it was revealed that the latter patient had severe underlying coronary artery disease.
Pharmacokinetics
On the basis of the IC90 (70 nmol/L) of enzastaurin for PKC (in vitro analysis) and the plasma protein binding (95%) values, the targeted mean steady-state total concentration for clinical efficacy is approximately 1,400 nmol/L. This steady state is achieved within 2 weeks of daily oral dosing, consistent with the observed half-life of enzastaurin and its metabolites. Because the 525-mg once daily dose produced the targeted steady-state concentration of 1,400 nmol/L and did not result in unacceptable toxicity, it was chosen as the recommended phase II dose and for enrollment of additional patients in the 525-mg cohort. Substantial interpatient variability in pharmacokinetic parameters was apparent at any dose level (coefficient of variation for apparent clearance, up to 127%), implying varied systemic exposure to enzastaurin. Preliminary results obtained by fluorescence-activated cell sorting (FACS) analysis of PBMCs indicate that enzastaurin treatment reduced PKCβ activity in PBMCs (data not shown) in three of four patients in the 700-mg cohort (no day-28 sample for patient 3).
Antitumor Efficacy
On the basis of the overall toxicity and pharmacokinetic data observed in this phase I study, we recommended a dose of enzastaurin 525 mg once daily for phase II studies. This dose was well tolerated, and most patients achieved the targeted steady-state plasma concentration of 1,400 nmol/L, which did not further increase at 700 mg. Mouse xenograft studies have since shown xenograft-suppressing activity at plasma exposures similar to those observed in this study.19 Future studies combined with a pharmacodynamic biomarker may further support this conclusion. In this study, enzastaurin was well tolerated at doses up to 700 mg/d. No MTD was observed. No clinically significant toxicities or deaths related to enzastaurin were reported. Both reports of QTc prolongation (reported in two patients) were transient, with no clinical consequence, and did not result in treatment discontinuation. One event of ST-T wave change was reported as drug-related, although confounding factors such as a previous history of nonspecific ST-T wave changes and concomitant medications were present. Nine patients remained on therapy for at least six cycles without any serious adverse events. The plasma exposures of enzastaurin in this study indicate high interpatient variability at a given dose. Enzastaurin and its metabolite, LY326020, are primarily metabolized by CYP3A, an enzyme with highly variable (four- to five-fold) activity in the general population and 14-fold in cancer patients.30-32 This variability may have contributed to the observed interpatient differences in enzastaurin pharmacokinetics. In addition, because enzastaurin has poor solubility and food effect is anticipated, the differences in the patient's intake of doses relative to meals can cause variability. Because of the pH-dependent solubility, altered nutrition levels and differences in gastric emptying rates could also affect absorption. There was also some evidence of less than dose-proportional increases at higher doses. However, the variability observed in the data and the limited number of patients in each cohort does not allow a valid inference on dose proportionality. The exposure after the 700 mg dose was no different from the exposure at 525 mg. Further studies with higher daily doses and twice-a-day regimens are being conducted to determine if higher exposures can be achieved. Because this was a phase I study, efficacy was not a primary end point. Objective tumor responses were not identified; however, several patients with heavily pretreated lung cancer, colorectal carcinoma, and renal carcinoma demonstrated prolonged disease stabilization. Flow cytometry analysis supports the hypothesis that enzastaurin reduces the activity of its major target, PKCβ. Although only four samples were used in this analysis because of unavailability of a validated assay at the beginning of the trial, similar results were obtained from another phase I trial.28 At a 525-mg dose, plasma concentrations are enough to inhibit most PKC isoforms and other kinases, including AKT, ribosomal S6 kinase, and GSK3.19 This suggests that enzastaurin targets cancer using multiple pathways: inhibition of tumor cell proliferation, direct induction of apoptosis, and suppression of angiogenesis. Phase II studies designed to measure tumor response and/or stable disease over a specified period (rate of freedom from progression) will provide more information on the expected antitumor activity of enzastaurin. It would be interesting to investigate whether enzastaurin's activity is enhanced in patients with cancers associated with elevated PKC or PI3K/AKT activity, such as lymphomas12 and gliomas.33 Other studies have shown that targeted agents work synergistically with cytotoxic agents.34,35 Hence, given the distinct toxicity profile and molecular targets, enzastaurin has the potential for use in combination studies with cytotoxic agents to enhance tumor shrinkage and prevent regrowth. Currently, phase I combination studies with gemcitabine, pemetrexed, cisplatin, and capecitabine are ongoing. Enzastaurin is also being investigated in phase II trials in patients with recurrent high grade gliomas,36 refractory diffuse large B-cell lymphoma,37 and mantle-cell lymphoma.
Although all authors completed the disclosure declaration, the following authors or their immediate family members indicated a financial interest. No conflict exists for drugs or devices used in a study if they are not being evaluated as part of the investigation. For a detailed description of the disclosure categories, or for more information about ASCO's conflict of interest policy, please refer to the Author Disclosure Declaration and the Disclosures of Potential Conflicts of Interest section in Information for Contributors.
Dollar Amount Codes (A) < $10,000 (B) $10,000-99,999 (C)
We acknowledge the staff at the investigator sites; Lisa Green, Chad Ray, Phil Marder, Shawn Flanagan, Barbara Ring, Hui Zheng, and John Baldwin for fluorescence-activated cell sorting, metabolism studies, and pharmacokinetics; Asavari Wagle, Noelle Gasco, Donna L. Miller, and Bich Tran for editorial and technical assistance.
Supported by Eli Lilly and Company, Indianapolis, IN 46285. Presented in abstract format at the 38th Annual Meeting of the American Society of Clinical Oncology, Orlando, FL, May 18-21, 2002. Authors' disclosures of potential conflicts of interest and author contributions are found at the end of this article.
1. Livneh E, Fishman DD: Linking protein kinase C to cell-cycle control. Eur J Biochem 248:1-9, 1997[Medline] 2. Nishizuka Y: Intracellular signaling by hydrolysis of phospholipids and activation of protein kinase C. Science 258:607-614, 1992 3. da Rocha AB, Mans DR, Regner A, et al: Targeting protein kinase C: New therapeutic opportunities against high-grade gliomas? Oncologist 7:17-33, 2002 4. Gescher A: Analogs of staurosporine: Potential anticancer drugs? Gen Pharmacol 31:721-728, 1998[Medline] 5. Goekjian PG, Jirousek MR: Protein kinase C inhibitors as novel anticancer drugs. Expert Opin Investig Drugs 10:2117-2140, 2001[CrossRef][Medline] 6. Blobe GC, Obeid LM, Hannun YA: Regulation of protein kinase C and role in cancer biology. Cancer Metastasis Rev 13:411-431, 1994[CrossRef][Medline] 7. Gokmen-Polar Y, Murray NR, Velasco MA, et al: Elevated protein kinase C betaII is an early promotive event in colon carcinogenesis. Cancer Res 61:1375-1381, 2001 8. Engers R, Mrzyk S, Springer E, et al: Protein kinase C in human renal cell carcinomas: Role in invasion and differential isoenzyme expression. Br J Cancer 82:1063-1069, 2000[CrossRef][Medline] 9. Tsai JH, Hsieh YS, Kuo SJ, et al: Alteration in the expression of protein kinase C isoforms in human hepatocellular carcinoma. Cancer Lett 161:171-175, 2000[CrossRef][Medline] 10. Clark AS, West KA, Blumberg PM, et al: Altered protein kinase C (PKC) isoforms in non-small cell lung cancer cells: PKCdelta promotes cellular survival and chemotherapeutic resistence. Cancer Res 63:780-786, 2003 11. Koren R, Ben Meir D, Langzam L, et al: Expression of protein kinase C isoenzymes in benign hyperplasia and carcinoma of the prostate. Oncol Rep 11:321-326, 2004[Medline] 12. Shipp MA, Ross KN, Tamayo P, et al: Diffuse large B-cell lymphoma outcome prediction by gene-expression profiling and supervised machine learning. Nat Med 8:68-74, 2002[CrossRef][Medline] 13. McMahon G: VEGF receptor signaling in tumor angiogenesis. Oncologist 5:3-10, 2000 (suppl 1) 14. Xia P, Aiello LP, Ishii H, et al: Characterization of vascular endothelial growth factor's effect on the activation of protein kinase C, its isoforms, and endothelial cell growth. J Clin Invest 98:2018-2026, 1996[Medline] 15. Yoshiji H, Kuriyama S, Ways DK, et al: Protein kinase C lies on the signaling pathway for vascular endothelial growth factor-mediated tumor development and angiogenesis. Cancer Res 59:4413-4418, 1999 16. Balendran A, Hare GR, Kieloch A, et al: Further evidence that 3-phosphoinositide-dependent protein kinase-1 (PDK1) is required for the stability and phosphorylation of protein kinase C (PKC) isoforms. FEBS Lett 484:217-223, 2000[CrossRef][Medline] 17. Partovian C, Simons M: Regulation of protein kinase B/Akt activity and Ser473 phosphorylation by protein kinase Calpha in endothelial cells. Cell Signal 16:951-957, 2004[CrossRef][Medline] 18. Faul MM, Gillig JR, Jirousek MR, et al: Acyclic N-(azacycloalkyl) bisindolylmaleimides: Isozyme selective inhibitors of PKCBeta. Bioorg Med Chem Lett 13:1857-1859, 2003[CrossRef][Medline] 19. Graff JR, McNulty AM, Hanna KR, et al: The protein kinase Cbeta–selective inhibitor, enzastaurin (LY317615.HCl), suppresses signaling through the AKT pathway, induces apoptosis, and suppresses growth of human colon cancer and glioblastoma xenografts. Cancer Res 65:7462-7469, 2005 20. Keyes KA, Mann L, Sherman M, et al: LY317615 decreases plasma VEGF levels in human tumor xenograft-bearing mice. Cancer Chemother Pharmacol 53:133-140, 2004[CrossRef][Medline] 21. Teicher BA, Alvarez E, Menon K, et al: Antiangiogenic effects of a protein kinase Cbeta-selective small molecule. Cancer Chemother Pharmacol 49:69-77, 2002[CrossRef][Medline] 22. Liu Y, Su W, Thompson EA, et al: Protein kinase CbetaII regulates its own expression in rat intestinal epithelial cells and the colonic epithelium in vivo. J Biol Chem 279:45556-45563, 2004 23. Keyes K, Cox K, Treadway P, et al: An in vitro tumor model: Analysis of angiogenic factor expression after chemotherapy. Cancer Res 62:5597-5602, 2002 24. Herbst RS: Targeted therapy using novel agents in the treatment of non-small-cell lung cancer. Clin Lung Cancer 3:S30-S38, 2002 (suppl 1)[Medline] 25. Simon R, Freidlin B, Rubinstein L, et al: Accelerated titration designs for phase I clinical trials in oncology. J Natl Cancer Inst 89:1138-1147, 1997 26. National Cancer Institute: Cancer Therapy Evaluation Program Common Toxicity Criteria, version 2.0, modified 1999. http://ctep.cancer.gov/reporting/CTC-3.html 27. Therasse P, Arbuck SG, Eisenhauer EA, et al: New guidelines to evaluate the response to treatment in solid tumors: European Organization for Research and Treatment of Cancer, National Cancer Institute of the United States, National Cancer Institute of Canada. J Natl Cancer Inst 92:205-216, 2000 28. Green L, Ray C, Jaken S, et al: Development and application of methods for intracellular phospho-protein detection for clinical biomarker analysis in drug development. Cytometry 59A:94, 2004 (abstr) 29. Chow S, Patel H, Hedley DW: Measurement of MAP kinase activation by flow cytometry using phospho-specific antibodies to MEK and ERK: Potential for pharmacodynamic monitoring of signal transduction inhibitors. Cytometry 46:72-78, 2001[CrossRef][Medline] 30. Wilkinson GR: Cytochrome P4503A (CYP3A) metabolism: Prediction of in vivo activity in humans. J Pharmacokinet Biopharm 24:475-490, 1996[CrossRef][Medline] 31. Baker SD, van Schaik RH, Rivory LP, et al: Factors affecting cytochrome P-450 3A activity in cancer patients. Clin Cancer Res 10:8341-8350, 2004 32. Guengerich FP: Influence of nutrients and other dietary materials on cytochrome P-450 enzymes. Am J Clin Nutr 61:651S-658S, 1995 (suppl 3)[Medline] 33. Chakravarti A, Zhai G, Suzuki Y, et al: The prognostic significance of phosphatidylinositol 3-kinase pathway activation in human gliomas. J Clin Oncol 22:1926-1933, 2004 34. Herbst RS: Targeted therapy using novel agents in the treatment of non-small-cell lung cancer. Clin Lung Cancer 3:S30-S38, 2002 (suppl 1)[Medline] 35. Kerbel RS: Clinical trials of antiangiogenic drugs: Opportunities, problems, and assessment of initial results. J Clin Oncol 19:45S-51S, 2001 (suppl 18)[Medline] 36. Fine HA, Kim L, Royce C, et al: Results from phase II trial of enzastaurin (LY317615) in patients with recurrent high grade gliomas. J Clin Oncol 23:155, 2005 (suppl; abstr 1504) 37. Robertson M, Kahl B, Vose J, et al: A phase II study of enzastaurin, a protein kinase C-β (PKCβ) inhibitor, in the treatment of relapsed diffuse large B-cell lymphoma. Blood 106:275a, 2005 (abstr 934) Submitted December 20, 2005; accepted May 19, 2006.
This article has been cited by other articles:
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|
|||||||||||
|
|||||||||||
|
|
Copyright © 2006 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
|
TOP
ABSTRACT
INTRODUCTION
