The Pharmacogenomics Journal (2010) 10, 191–199 & 2010 Nature Publishing Group All rights reserved 1470-269X/10 www.nature.com/tpj ORIGINAL ARTICLE A pharmacogenetic study of docetaxel and thalidomide in patients with castration-resistant prostate cancer using the DMET genotyping platform JF Deeken1, T Cormier2, The anticancer agent docetaxel shows significant inter-individual variation in 3 3 its pharmacokinetic and toxicity profile. Thalidomide is an active anticancer DK Price , TM Sissung , agent and also shows wide pharmacological variation. Past pharmacogenetic 4 2 SM Steinberg , K Tran , research has not explained this variation. Patients with prostate cancer DJ Liewehr4, WL Dahut3, enrolled in a randomized phase II trial using docetaxel and thalidomide X Miao2 and WD Figg3 versus docetaxel alone were genotyped using the Affymetrix DMET 1.0 platform, which tests for 1256 genetic variations in 170 drug disposition 1Lombardi Cancer Center, Georgetown University genes. Genetic polymorphisms were analyzed for associations with clinical Medical Center, Washington, DC, USA; response and toxicity. In all, 10 single-nucleotide polymorphisms (SNPs) in 2 3 Affymetrix, Inc., Santa Clara, CA, USA; Medical three genes were potentially associated with response to therapy: peroxisome Oncology Branch, National Cancer Institute, NIH, Bethesda, MD, USA and 4Biostatistics and Data proliferator-activated receptor-d (PPAR-d), sulfotransferase family, cytosolic, 1C, Management Section, National Cancer Institute, member 2 (SULT1C2) and carbohydrate (chondroitin 6) sulfotransferase 3 NIH, Bethesda, MD, USA (CHST3). In addition, 11 SNPs in eight genes were associated with toxicities to treatment: spastic paraplegia 7 (pure and complicated autosomal recessive) Correspondence: (SPG7), CHST3, cytochrome P450, family 2, subfamily D, polypeptide 6 Dr J Deeken, Lombardi Cancer Center, Georgetown University Medical Center, 3800 (CYP2D6), N-acetyltransferase 2 (arylamine N-acetyltransferase)(NAT2), ATP- Reservoir Road, NW, Washington, DC 20007, binding cassette, sub-family C (CFTR/MRP), member 6 (ABCC6), ATPase, USA. Cu þþtransporting, alpha polypeptide (ATP7A), cytochrome P450, family 4, E-mail: [email protected] subfamily B, polypeptide 1 (CYP4B1) and solute carrier family 10 (sodium/bile acid cotransporter family), member 2 (SLC10A2). Genotyping results between drug metabolizing enzymes and transporters (DMET) and direct sequencing showed 496% of concordance. These findings highlight the role that non- CYP450 metabolizing enzymes and transporters may have in the pharma- cology of docetaxel and thalidomide. The Pharmacogenomics Journal (2010) 10, 191–199; doi:10.1038/tpj.2009.57; published online 29 December 2009 Keywords: pharmacogenomics; docetaxel; thalidomide; prostate cancer Introduction Individualizing therapy for patients who are treated with pharmaceutical agents is an overarching goal of basic and clinical research in this first part of the twenty-first century. In no area of medicine is this goal more critical than in medical oncology. Genetic variation in genes encoding proteins involved in Received 24 November 2008; revised 16 October 2009; accepted 1 November 2009; the metabolism and transport of drugs may account for some of the wide published online 29 December 2009 variation observed in the response to, and toxicity from, anticancer agents. Pharmacogenetics of docetaxel and thalidomide JF Deeken et al 192 Pharmacogenetic research holds the promise of reducing the sequencing of specific gene fragments. This work is unpredictable inter-individual variability in the efficacy and specialized and labor intensive, which in turn limits the toxicity from using chemotherapy drugs. institutions and investigators who can pursue genotyping Enzymes and transporters mediate the absorption, dis- and pharmacogenetic research. One of the main obstacles tribution, metabolism and excretion of endogenous as well facing pharmacogenetic researchers is the lack of a proven, as exogenous substrates, including drugs. However, for only scalable genotyping technology that screens for SNPs in a relatively small number of absorption, distribution, meta- multiple genes with sufficient sensitivity and high-through- bolism and excretion genes have single nucleotide polymor- put capabilities to be useful in translational and clinical phisms (SNPs) and other genetic variations been identified research. The new Affymetrix drug-metabolizing enzyme that mediate the efficacy and toxicity of chemotherapy drugs. and transporter (DMET) genotyping platform (Affymetrix, These include irinotecan and UGT1A1, 6-mercaptopurine and Inc., Santa Clara, CA, USA) screens for 1256 genetic vari- thiopurine methyltransferase, 5-fluoruracil and dihydropyrimidine ations in 170 absorption, distribution, metabolism and dehydrogenase and tamoxifen and cytochrome P450, family 2, excretion genes, including 50 CYP450 genes, 72 non-CYP subfamily D, polypeptide 6 (CYP2D6).1 genes, 39 transporters and 9 other proteins involved in drug Docetaxel (Taxotere) is a semisynthetic taxane that is disposition (Table 1).24 We tested this new genotyping currently used as first-line therapy in castration-resistant platform, termed DMET, using patient samples and clinical prostate cancer (CRPC). It is thought that the major route of data from our previously completed phase II trial in patients metabolism is through the CYP3A family of enzymes.2–4 The with CRPC to analyze the pharmacogenetics of thalidomide pharmacokinetic profile of docetaxel shows wide inter- and docetaxel. individual variability, with measures such as clearance and area under the concentration curve varying as much as sixfold between patients.5,6 Even in an ethnically homo- genous patient population, variability is as high as 3.5-fold.7 Patients and methods Research using probes of CYP3A4 activity have been unsuccessful in explaining this large variation.7–10 In fact, Patients the activity of CYP3A4/3A5 accounts for as little as two- Patients diagnosed with CRPC were enrolled in a rando- thirds of the inter-individual variable pharmacology of the mized phase II clinical trial comparing docetaxel to drug.6,11 This led researchers to look at other metabolizing docetaxel with thalidomide. The results of this trial have enzymes, including glutathione-S-transferases, as well as been previously reported.25 In brief, 74 patients with CRPC drug transporters such as ABCB1 (P-glycoprotein), to help were enrolled with a 2:1 randomization to receive either explain this large variability in drug pharmacology.11–14 docetaxel and thalidomide, or docetaxel alone. Docetaxel The pharmacogenetic factors mediating docetaxel pharma- was dosed at 30 mg m–2 weekly for 3 weeks followed by a cokinetics have not been fully characterized.14 We have 1-week rest. For patients assigned to the combination arm, previously proposed that a more comprehensive analysis they received docetaxel on the same schedule, as well as into the expression and genetic polymorphisms of multiple thalidomide at 200 mg orally each day. In all, 49 patients drug enzymes and transporters may improve our under- were in the combination arm and 25 patients were in the standing of the pharmacokinetics of docetaxel.15 control arm.25 The study was approved by the institutional Thalidomide, a potent teratogen that causes dysmelia in review board of the National Cancer Institute. humans, has been approved for the treatment of multiple Response to treatment was determined using the prostate- myeloma and is under active clinical analysis for its use in specific antigen Working Group consensus criteria of a drop treating other malignancies. The anticancer mechanism of in serum prostate-specific antigen of X50% with no other action of thalidomide is complex and has not yet been fully evidence of disease progression. Toxicities were graded using charecterized. In vitro data suggest that it inhibits angiogen- the Common Toxicity Criteria (version 2.0) of the Cancer esis. Non-enzymatic spontaneous hydrolysis is a major route Therapy Evaluation Program/National Cancer Institute. For of metabolism, with at least 12 different products identified this pharmacogenetic study, only adverse reactions graded by this process.16 However, enzymatic activation of these as 3 (no grade 4 adverse events were experienced on this hydrolysis products is necessary for thalidomide to exert its trial) and identified as being possibly, probably or definitely anticancer activity.17–19 Two metabolites, 5-hydroxythalido- related to study medications were included. Events of bone mide and 50-hydroxythalidomide, are formed by CYP2C19 pain, which is common in this patient population, as well and to a lesser extent CYP2B6.20 CYP1A1 may have a role in as events of hyperglycemia (which were likely caused by parent drug activation.21 Other metabolism products, the use of dexamethasone as a docetaxel pre-medication) including dihydroxylated and glucuronide conjugates, have were not included. Finally, events of venous thrombosis been found in animal models.22 Past pharmacogenetic were not included because the trial was modified to add low- studies analyzing whether SNPs in CYP2C19 accounted for molecular-weight heparin to patients receiving thalidomide the inter-individual variation in pharmacokinetics and after an interim analysis found a high rate of such events toxicities have been inconclusive.19,23 early in the trial. Toxicity was used as a pharmacodynamic Testing for the presence of genetic variations and SNPs is measure as well