Stephanie L. Safgren

Association between CYP2D6 polymorphisms and outcomes among women with early stage breast cancer treated with tamoxifen.

CONTEXT The growth inhibitory effect of tamoxifen, which is used for the treatment of hormone receptor-positive breast cancer, is mediated by its metabolites, 4-hydroxytamoxifen and endoxifen. The formation of active metabolites is catalyzed by the polymorphic cytochrome P450 2D6 (CYP2D6) enzyme. OBJECTIVE To determine whether CYP2D6 variation is associated with clinical outcomes in women receiving adjuvant tamoxifen. DESIGN, SETTING, AND PATIENTS Retrospective analysis of German and US cohorts of patients treated with adjuvant tamoxifen for early stage breast cancer. The 1325 patients had diagnoses between 1986 and 2005 of stage I through III breast cancer and were mainly postmenopausal (95.4%). Last follow-up was in December 2008; inclusion criteria were hormone receptor positivity, no metastatic disease at diagnosis, adjuvant tamoxifen therapy, and no chemotherapy. DNA from tumor tissue or blood was genotyped for CYP2D6 variants associated with reduced (*10, *41) or absent (*3, *4, *5) enzyme activity. Women were classified as having an extensive (n=609), heterozygous extensive/intermediate (n=637), or poor (n=79) CYP2D6 metabolism. MAIN OUTCOME MEASURES Time to recurrence, event-free survival, disease-free survival, and overall survival. RESULTS Median follow-up was 6.3 years. At 9 years of follow-up, the recurrence rates were 14.9% for extensive metabolizers, 20.9% for heterozygous extensive/intermediate metabolizers, and 29.0% for poor metabolizers, and all-cause mortality rates were 16.7%, 18.0%, and 22.8%, respectively. Compared with extensive metabolizers, there was a significantly increased risk of recurrence for heterozygous extensive/intermediate metabolizers (time to recurrence adjusted hazard ratio [HR], 1.40; 95% confidence interval [CI], 1.04-1.90) and for poor metabolizers (time to recurrence HR, 1.90; 95% CI, 1.10-3.28). Compared with extensive metabolizers, those with decreased CYP2D6 activity (heterozygous extensive/intermediate and poor metabolism) had worse event-free survival (HR, 1.33; 95% CI, 1.06-1.68) and disease-free survival (HR, 1.29; 95% CI, 1.03-1.61), but there was no significant difference in overall survival (HR, 1.15; 95% CI, 0.88-1.51). CONCLUSION Among women with breast cancer treated with tamoxifen, there was an association between CYP2D6 variation and clinical outcomes, such that the presence of 2 functional CYP2D6 alleles was associated with better clinical outcomes and the presence of nonfunctional or reduced-function alleles with worse outcomes.

Phase I Trial of 17-Allylamino-17-Demethoxygeldanamycin in Patients With Advanced Cancer

PURPOSE We determined the maximum-tolerated dose (MTD) and the dose-limiting toxicities (DLT) of 17-allylamino-17-demethoxygeldanamycin (17-AAG) when infused on days 1, 8, and 15 of a 28-day cycle in advanced solid tumor patients. We also characterized the pharmacokinetics of 17-AAG, its effect on chaperone and client proteins, and whether cytochrome P450 (CYP) 3A5 and NAD(P)H:quinone oxidoreductase 1 (NQO1) polymorphisms affected 17-AAG disposition or toxicity. PATIENTS AND METHODS An accelerated titration design was used. Biomarkers were measured in peripheral-blood mononuclear cells (PBMCs) at baseline and on days 1 and 15, and pharmacokinetic analysis was performed on day 1 of cycle 1. CYP3A5*3 and NQO1*2 genotypes were determined and correlated with pharmacokinetics and toxicity. RESULTS Twenty-one patients received 52 courses at 11 dose levels. DLTs at 431 mg/m(2) were grade 3 bilirubin (n = 1), AST (n = 1), anemia (n = 1), nausea (n = 1), vomiting (n = 1), and myalgias (n = 1). No tumor responses were seen. 17-AAG consistently increased heat shock protein (Hsp) 70 levels in PBMCs. At the MTD, the clearance and half-life (t(1/2)) of 17-AAG were 11.6 L/h/m(2) and 4.15 hours, respectively; whereas the active metabolite 17-aminogeldanamycin had a t(1/2) of 7.63 hours. The CYP3A5*3 and NQO1*2 polymorphisms were not associated with 17-AAG toxicity. The CYP3A5*3 polymorphism was associated with higher 17-AAG clearance. CONCLUSION The MTD of weekly 17-AAG is 308 mg/m(2). 17-AAG induced Hsp70 in PBMCs, indicating that Hsp90 has been affected. Further evaluation of 17-AAG is ongoing using a twice-weekly regimen, and this schedule of 17-AAG is being tested in combination with chemotherapy.

Targeted Delivery of Gemcitabine to Pancreatic Adenocarcinoma Using Cetuximab as a Targeting Agent

One of the key challenges in anticancer therapy is the toxicity and poor bioavailability of the anticancer drugs. Nanotechnology can play a pivotal role by delivering drugs in a targeted fashion to the malignant cells that will reduce the systemic toxicity of the anticancer drug. In this report, we show a stepwise development of a nanoparticle-based targeted delivery system for in vitro and in vivo therapeutic application in pancreatic cancer. In the first part of the study, we have shown the fabrication and characterization of the delivery system containing gold nanoparticle as a delivery vehicle, cetuximab as a targeting agent, and gemcitabine as an anticancer drug for in vitro application. Nanoconjugate was first characterized physico-chemically. In vitro targeting efficacy, tested against three pancreatic cancer cell lines (PANC-1, AsPC-1, and MIA Paca2) with variable epidermal growth factor receptor (EGFR) expression, showed that gold uptake correlated with EGFR expression. In the second part, we showed the in vivo therapeutic efficacy of the targeted delivery system. Administration of this targeted delivery system resulted in significant inhibition of pancreatic tumor cell proliferation in vitro and orthotopic pancreatic tumor growth in vivo. Tumor progression was monitored noninvasively by measuring bioluminescence of the implanted tumor cells. Pharmacokinetic experiments along with the quantitation of gold both in vitro and in vivo further confirmed that the inhibition of tumor growth was due to targeted delivery. This strategy could be used as a generalized approach for the treatment of a variety of cancers characterized by overexpression of EGFR.

A Phase I Trial of Twice-Weekly 17-Allylamino-Demethoxy-Geldanamycin in Patients with Advanced Cancer

Purpose: To determine the maximum tolerated dose (MTD), dose-limiting toxicity, and pharmacokinetics of 17-allylamino-demethoxy-geldanamycin (17-AAG) administered on days 1, 4, 8, and 11 every 21 days and to examine the effect of 17-AAG on the levels of chaperone and client proteins. Experimental Design: A phase I dose escalating trial in patients with advanced solid tumors was done. Toxicity and tumor responses were evaluated by standard criteria. Pharmacokinetics were done and level of target proteins was measured at various points during cycle one. Results: Thirteen patients were enrolled in the study. MTD was defined as 220 mg/m2. Dose-limiting toxicities were as follows: dehydration, diarrhea, hyperglycemia, and liver toxicity. At the MTD, the mean clearance of 17-AAG was 18.7 L/h/m2. There was a significant decrease in integrin-linked kinase at 6 hours after infusion on day 1 but not at 25 hours in peripheral blood mononuclear cells. Treatment with 17-AAG on day 1 significantly increased pretreatment levels of heat shock protein (HSP) 70 on day 4, which is consistent with the induction of a stress response. In vitro induction of a stress response and up-regulation of HSP70 resulted in an increased resistance to HSP90-targeted therapy in A549 cells. Conclusions: The MTD of 17-AAG on a twice-weekly schedule was 220 mg/m2. Treatment at this dose level resulted in significant changes of target proteins and also resulted in a prolonged increase in HSP70. This raises the possibility that HSP70 induction as part of the stress response may contribute to resistance to 17-AAG.

CYP2D6 Metabolism and Patient Outcome in the Austrian Breast and Colorectal Cancer Study Group Trial (ABCSG) 8

Purpose: Controversy exists about CYP2D6 genotype and tamoxifen efficacy. Experimental Design: A matched case–control study was conducted using the Austrian Breast and Colorectal Cancer Study Group Trial 8 (ABCSG8) that randomized postmenopausal women with estrogen receptor (ER)-positive breast cancer to tamoxifen for 5 years (arm A) or tamoxifen for 2 years followed by anastrozole for 3 years (arm B). Cases had disease recurrence, contralateral breast cancer, second non–breast cancer, or died. For each case, controls were identified from the same treatment arm of similar age, surgery/radiation, and tumor–node—metastasis (TNM) stage. Genotyping was conducted for alleles associated with no (PM; *3, *4, *6), reduced (IM; *10, and *41), and extensive (EM: absence of these alleles) CYP2D6 metabolism. Results: The common CYP2D6*4 allele was in Hardy–Weinberg equilibrium. In arm A during the first 5 years of therapy, women with two poor alleles [PM/PM: OR, 2.45; 95% confidence interval (CI), 1.05–5.73, P = 0.04] and women with one poor allele (PM/IM or PM/EM: OR, 1.67; 95% CI, 0.95–2.93; P = 0.07) had a higher likelihood of an event than women with two extensive alleles (EM/EM). In years 3 to 5 when patients remained on tamoxifen (arm A) or switched to anastrozole (arm B), PM/PM tended toward a higher likelihood of a disease event relative to EM/EM (OR, 2.40; 95% CI, 0.86–6.66; P = 0.09) among women on arm A but not among women on arm B (OR, 0.28; 95% CI, 0.03–2.30). Conclusion: In ABCSG8, the negative effects of reduced CYP2D6 metabolism were observed only during the period of tamoxifen administration and not after switching to anastrozole. Clin Cancer Res; 19(2); 500–7. ©2012 AACR.

A phase I study of 17-allylaminogeldanamycin in relapsed/refractory pediatric patients with solid tumors: A children's oncology group study

Purpose: To determine the recommended phase 2 dose, dose-limiting toxicities (DLT), pharmacokinetic profile, and pharmacodynamics of the heat shock protein (Hsp) 90 inhibitor, 17-allylaminogeldanamycin (17-AAG). Experimental Design: 17-AAG was administered as a 60-min infusion, on days 1, 4, 8, and 11 of a 21-day cycle at dose levels of 150, 200, 270, and 360 mg/m2/dose. Pharmacokinetic studies and evaluations for Hsp72 and Akt levels in peripheral blood mononuclear cells were done during the first course of therapy. Results: Seventeen patients (7 males), median 7 years of age (range, 1-19 years), were enrolled using a standard dose escalation scheme. No DLTs were observed. Although there were no objective responses, three patients remain on therapy at 6+, 7+, and 9+ months with stable disease. One patient with hepatoblastoma had a reduction in α-fetoprotein and stable disease over three cycles. At 270 mg/m2/dose, the Cmax and areas under the plasma concentration-time curves of 17-AAG were 5,303 ± 1,591 ng/mL and 13,656 ± 4,757 ng/mL h, respectively, similar to the exposure in adults. The mean terminal half-life for 17-AAG was 3.24 ± 0.80 h. Induction of Hsp72, a surrogate marker for inhibition of Hsp90, was detected at the 270 mg/m2 dose level. Conclusions: Drug exposures consistent with those required for anticancer activity in preclinical models were achieved without DLT. Evidence for drug-induced modulation of Hsp90 systemically was also detected. The recommended phase II dose of 17-AAG is 360 mg/m2/d. Non-DMSO–containing formulations may improve acceptance of this drug by children and their families.

Phase I trial of two schedules of vincristine, oral irinotecan, and temozolomide (VOIT) for children with relapsed or refractory solid tumors: a Children's Oncology Group phase I consortium study.

In preclinical models, temozolomide, and vincristine are additive or synergistic with irinotecan. We examined this three‐drug combination in children with relapsed solid tumors. Patients received orally administered irinotecan together with temozolomide and vincristine on two different schedules, using cefixime to reduce irinotecan‐associated diarrhea.

Evaluation of CYP2D6 and Efficacy of Tamoxifen and Raloxifene in Women Treated for Breast Cancer Chemoprevention: Results from the NSABP P1 and P2 Clinical Trials

Background: Controversy exists regarding the association between CYP2D6 enzyme activity and tamoxifen effectiveness in the adjuvant treatment of invasive breast cancer; however, this association in the primary prevention of breast cancer is unknown. Methods: We conducted a nested case–control study in the context of the NSABP P1 and P2 prevention trials to determine the impact of CYP2D6 genotype, CYP2D6 inhibitor use, and metabolizer status (CYP2D6 genotype combined with CYP2D6 inhibitor use), on breast cancer events. Women who developed breast cancer (both noninvasive and invasive) while on 5 years of selective estrogen receptor modulators therapy (cases) were matched to controls free of breast cancer. Comprehensive CYP2D6 genotyping was conducted for alleles associated with absent (*3, *4, *5, and *6), reduced (*10, *17, and *41), and increased (*1XN and *2XN) enzyme activity. Information regarding the use of CYP2D6 inhibitors was recorded. Results: A total of 591 cases were matched to 1,126 controls and DNA was genotyped in more than 97%. In patients treated with tamoxifen, there was no association of CYP2D6 genotype [OR (extensive/poor metabolizer): 0.90; 95% CI: 0.46–1.74, P = 0.74), use of a potent CYP2D6 inhibitor (OR 0.92; 95% CI: 0.575–1.486), or CYP2D6 metabolizer status (OR 1.03; 95% CI: 0.669–1.607) with breast cancer occurrence. Likewise, there was no association between any CYP2D6 metabolism parameter with breast cancer events in raloxifene-treated patients. Conclusion: In the NSABP P1 and P2 clinical trials, alterations in CYP2D6 metabolism are not associated with either tamoxifen or raloxifene efficacy. Clin Cancer Res; 17(21); 6944–51. ©2011 AACR.

SULT1A1, CYP2C19 and disease-free survival in early breast cancer patients receiving tamoxifen

AIM Tamoxifen biotransformation to endoxifen, a potent antiestrogen, is catalyzed by CYP2D6. In addition, CYP2C19 and SULT1A1 have also been implicated in the metabolism of tamoxifen. We sought to evaluate the importance of SULT1A1 copy number and CYP2C19*17 on disease-free survival (DFS) in postmenopausal women randomized to tamoxifen monotherapy in North Central Cancer Treatment Group 89-30-52 from January 1991 to April 1995. MATERIALS & METHODS We extracted DNA from paraffin-embedded tumors and determined tumor SULT1A1 copy number and CYP2C19*17 genotype. The association of genotype with DFS was determined using the log-rank test. Multivariate cox modeling was performed using traditional prognostic factors, as well as CYP2D6 genotype. SULT1A1 copy number and CYP2C19*17 genotype was determined in 190 out of 256 patients (95% Caucasian). RESULTS The median follow-up for living patients was 14 years. DFS did not differ according to SULT1A1 copy number (p = 0.482) or CYP2C19*17 genotype (p = 0.667). Neither SULT1A1 copy number or CYP2C19*17 genotype was associated with disease recurrence in this cohort. CONCLUSION Future studies are needed to identify whether other genetic and environmental factors which affect tamoxifen metabolism are associated with tamoxifen clinical outcomes.

Phase I and Pharmacologic Study of Infusional Topotecan and Carboplatin in Relapsed and Refractory Acute Leukemia

Purpose: To assess the maximum tolerated dose, toxicities, pharmacokinetics, and antileukemic activity of topotecan and carboplatin in adults with recurrent or refractory acute leukemias. Experimental Design: Patients received topotecan and carboplatin by 5-day continuous infusion at nine dose levels. Patients achieving a complete remission received up to two additional courses for consolidation. Plasma topotecan and ultrafilterable platinum were assayed on days 1 to 5. In addition, pretreatment levels of various polypeptides in leukemic cells were examined by immunoblotting to assess possible correlations with response. Results: Fifty-one patients received a total of 69 courses of therapy. Dose-limiting toxicity consisted of grade 4/5 typhlitis and grade 3/4 mucositis after one course of therapy or grade 4 neutropenia and thrombocytopenia lasting >50 days when a second course was administered on day 21. Among 45 evaluable patients, there were 7 complete remissions, 2 partial remissions, 1 incomplete complete remission, and 1 reversion to chronic-phase chronic myelogenous leukemia. Topotecan steady-state plasma concentrations increased with dose. No accumulation of topotecan or ultrafilterable platinum occurred between days 1 and 5 of therapy. Leukemic cell levels of topoisomerase I, checkpoint kinase 1, checkpoint kinase 2, and Mcl-1 correlated with proliferating cell nuclear antigen but not with response. In contrast, low Bcl-2 expression correlated with response (P = 0.014, Mann-Whitney U test). Conclusions: The maximum tolerated dose was 1.6 mg/m2/d topotecan plus 150 mg/m2/d carboplatin. The complete remission rate in a heavily pretreated population was 16% (33% at the highest three dose levels). Responses seem to correlate with low pretreatment blast cell Bcl-2 expression.