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Annual Meeting Proceedings Part 1 - American Society of Clinical ...

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166s Developmental Therapeutics—<strong>Clinical</strong> Pharmacology and Immunotherapy<br />

2597 General Poster Session (Board #8F), Mon, 8:00 AM-12:00 PM<br />

<strong>Clinical</strong> pharmacologic considerations for the phase II/III dose/regimen <strong>of</strong><br />

the investigational Aurora A kinase (AAK) inhibitor MLN8237 (alisertib):<br />

Pharmacokinetics (PK), pharmacodynamics (PD), and exposure-safety<br />

relationships. Presenting Author: Karthik Venkatakrishnan, <strong>Clinical</strong> Pharmacology,<br />

Millennium Pharmaceuticals, Inc., Cambridge, MA<br />

Background: MLN8237, an oral selective AAK inhibitor, is primarily<br />

metabolized by multiple glucuronidation enzymes including the polymorphic<br />

UGT1A1. Phase 1 studies included comprehensive PK and PD<br />

sampling. We report integrated PK, PD, and PK-safety analyses in support<br />

<strong>of</strong> dose/regimen selection for phase 2/3 studies. Methods: Phase 1 studies<br />

in adults with advanced cancers evaluated dosing on d 1-7 in 21-d cycles or<br />

d 1-21 in 35-d cycles. Data from 294 patients in 4 phase 1 and 2 phase 2<br />

studies contributed to population PK modeling. PD endpoints included<br />

mitotic index (MI) in skin and chromosome alignment and spindle<br />

bipolarity (CA/SB) in mitotic tumor cells. Logistic regression analyses<br />

evaluated relationships between MLN8237 PK parameters and DLTs<br />

(N�86) or CNS adverse events (AEs; n�134) in 2 phase 1 studies. Results:<br />

MLN8237 displayed dose-linear PK (5-200 mg/d), described by a 2-compartment<br />

model with first order absorption. Covariate analyses did not<br />

reveal significant effects <strong>of</strong> age, body size, sex, UGT1A1 genotype, or<br />

creatinine clearance (�30 mL/min). Exposure-related increases in skin MI<br />

and decreases in CA/SB in tumor mitotic cells confirmed AAK inhibition by<br />

MLN8237. At the MTD <strong>of</strong> 50 mg BID (d 1-7 dosing) geometric mean<br />

steady-state exposures (48,200 nM.hr) were comparable to those associated<br />

with �50% CA/SB reductions in mitotic tumor cells (57,300 nM.hr).<br />

Exposures at the 21-d MTD (QD dosing) were lower, favoring 50 mg BID (d<br />

1-7 dosing) for further development. At 50 mg BID (d 1-7 dosing) logistic<br />

regression relating MLN8237 AUC to DLT rate estimated a DLT probability<br />

<strong>of</strong> 8% (95% CI 3-20%). Similar analyses identified Cmax rather than AUC as<br />

the predictor <strong>of</strong> CNS AEs, supporting BID dosing in adults to reduce peak<br />

concentrations while preserving total systemic exposure. Conclusions:<br />

MLN8237 exhibits dose-linear PK independent <strong>of</strong> age, body size, mild or<br />

moderate renal impairment, or UGT1A1*28 polymorphism. Exposures<br />

achieved at or near 50 mg BID are expected to result in tumor AAK<br />

inhibition, supporting a pharmacologically active dose range for future<br />

clinical development.<br />

2599 General Poster Session (Board #8H), Mon, 8:00 AM-12:00 PM<br />

Effects <strong>of</strong> metformin and sulfonylureas on overall and colorectal cancerspecific<br />

mortality. Presenting Author: Susan Spillane, Trinity College<br />

Dublin, Dublin, Ireland<br />

Background: Preclinical studies have suggested a role for metformin in the<br />

treatment <strong>of</strong> colorectal cancer (CRC). Associations between metformin<br />

versus sulfonylurea exposure and mortality (all-cause and colorectal cancer<br />

specific) are assessed in this population-based study <strong>of</strong> patients with a<br />

diagnosis <strong>of</strong> stage I-IV CRC. Methods: National Cancer Registry Ireland<br />

records were linked to prescription claims data and used to identify a cohort<br />

<strong>of</strong> patients with incident TNM stage I-IV CRC diagnosed 2001-2006. From<br />

this cohort, 2 patient groups were identified and compared for outcomes -<br />

those who received a prescription for metformin �/- a sulfonylurea (MET) or<br />

a prescription for sulfonylurea alone (SUL) in the 90 days pre CRC<br />

diagnosis. Adjusted hazard ratios (HR) with 95% confidence intervals (CI)<br />

were estimated using Cox proportional hazards models adjusted for age,<br />

sex, stage, grade, site, comorbidities, year <strong>of</strong> diagnosis, and insulin, aspirin<br />

or statin exposure. Analyses were repeated stratifying by stage and site.<br />

Results: 5,617 patients with stage I-IV CRC were identified, <strong>of</strong> whom 369<br />

received a prescription for metformin or a sulfonylurea in the 90 days pre<br />

diagnosis (median follow-up 1.6 years; MET: n�257; SUL: n�112). In<br />

adjusted analyses metformin exposure was associated with a 28% lower<br />

risk <strong>of</strong> all-cause mortality relative to sulfonylurea exposure (HR 0.72, 95%<br />

CI 0.53-0.98) and a non-significant 24% reduction in CRC-specific<br />

mortality (HR 0.76, 95% CI 0.52-1.13). In analyses stratified by site, in<br />

colon cancer, metformin exposure was associated with a significant<br />

one-third reduction in all-cause mortality (HR 0.66, 95% CI 0.46-0.95)<br />

and a non-significant reduction in site-specific mortality (HR 0.64, 95% CI<br />

0.40-1.02). No mortality benefit was observed for rectal cancer. The<br />

association between metformin exposure and reduced mortality was strongest<br />

for stage I/II disease (all-cause mortality: HR 0.56, 95% CI 0.32-<br />

0.98; CRC-specific mortality: HR 0.48, 95% CI 0.21-1.11). Conclusions:<br />

Pre-diagnosis metformin exposure in CRC patients was associated with a<br />

significant reduction in mortality relative to sulfonylurea exposure. This<br />

benefit was greatest in patients with colon cancer and early stage disease.<br />

2598 General Poster Session (Board #8G), Mon, 8:00 AM-12:00 PM<br />

Docetaxel pharmacogenetics: The influence <strong>of</strong> RXR� and HNF4� genetic<br />

variations on docetaxel disposition in Asian nasopharyngeal carcinoma<br />

patients. Presenting Author: Sin Chi Chew, Division <strong>of</strong> Medical Sciences,<br />

National Cancer Centre, Singapore<br />

Background: The transactivations <strong>of</strong> the metabolism enzymes (CYP3A4/5)<br />

and efflux transporters (ABCB1/ABCC2) involved in docetaxel disposition<br />

are regulated by the orphan nuclear receptors such as PXR, CAR, RXR� and<br />

HNF4�. This study aimed to explore the associations between the genetic<br />

variations present in the genes encoding the orphan nuclear receptors,<br />

RXR� and HNF4�, on docetaxel disposition. Methods: The DNAs from<br />

healthy Chinese, Malay and Indian subjects (n�56 each) were screened for<br />

RXR� and HNF4� SNPs in exons and intronic/exonic boundaries by direct<br />

sequencing. The high frequency SNPs (�1%) were pr<strong>of</strong>iled in a cohort <strong>of</strong><br />

local nasopharyngeal cancer patients (n�54). Genotypic-phenotypic correlations<br />

were conducted using Mann-Whitney U-test and Kruskal-Wallis<br />

test. Results: Eighty-eight and sixty-nine SNPs were identified from the<br />

healthy screening <strong>of</strong> RXR� and HNF4�, respectively, across 3 populations.<br />

A total <strong>of</strong> 30 and 35 high frequency SNPs in RXR� and HNF4�,<br />

respectively, were pr<strong>of</strong>iled in the patients. Six RXR� SNPs [IVS2�33G�A<br />

(rs2234753), IVS7�70A�G (rs1536475),*846G�A (rs4240711),<br />

*�4458G�A (rs3132291), *�4768C�A (rs4842196) and *�4988A�G<br />

(rs4842198)] and 6 HNF4� SNPs [-728A�C (rs1800963), IVS2-<br />

278A�G (rs55934816), IVS6�141A�G (rs6103731), IVS7-88T�C<br />

(rs2273618), IVS9–145T�C (rs3746574) and IVS9-67C�G<br />

(rs3746575)] were significantly associated with higher clearance and<br />

lower AUC0-� and/or Cmax <strong>of</strong> docetaxel (P�0.05). Conversely, HNF4� SNP<br />

[IVS9�354G�T (rs3818247)] was associated with lower clearance and<br />

higher AUC0-� and Cmax <strong>of</strong> docetaxel (p�0.05). A high linkage pattern was<br />

observed among the abovementioned RXR� SNPs except for IVS2�33G�A<br />

(rs2234753) (D’�0.74). Similarly, HNF4� SNPs were found to be highly<br />

linked, except for -728A�C (rs1800963) (D’�0.62). Conclusions: The<br />

results highlight the contributions <strong>of</strong> RXR� and HNF4� pharmacogenetics<br />

in influencing the inter-individual variability in docetaxel disposition in<br />

Asian nasopharyngeal patients.<br />

2600 General Poster Session (Board #9A), Mon, 8:00 AM-12:00 PM<br />

Antibody-dependent cell-mediated cytotoxicity (ADCC) evolution under<br />

treatment by cetuximab and links with treatment outcome in colorectal<br />

cancer (CRC) patients. Presenting Author: Marco Carlo Merlano, St. Croce<br />

General Hospital, Cuneo, Italy<br />

Background: ADCC plays a role in antitumor activity <strong>of</strong> IgG1 mAb by<br />

inducing immune cell-mediated lysis <strong>of</strong> tumor cells. We evaluated ADCC<br />

ability before and under cetuximab-based treatment and examined its<br />

impact on treatment outcome. Methods: 29 patients (17 men, 12 women,<br />

median age 72, range 51-84) with metastatic wild-type KRAS CRC treated<br />

with chemotherapy (irinotecan or Folfiri) plus cetuximab were prospectively<br />

enrolled. ADCC ex-vivo was measured before starting treatment and every 2<br />

months during treatment (1 to 7 measurements/patient, 12 patients with<br />

�2 measurements). 400 000 purified Natural Killer cells (CD3- CD56�)<br />

from patients were incubated with 10 000 target cells (CAL166 cancer cell<br />

line expressing EGFR) and 10 �g/ml cetuximab (triplicates). Cytotoxicity<br />

was measured by the LDH-release assay. ADCC was expressed as the % <strong>of</strong><br />

lyzed target cells. Gene polymorphisms <strong>of</strong> Fc� receptors FCGR2a<br />

(131Arg�His) and FCGR3a (158Phe�Val) were analyzed (Allelic Discrimination<br />

assay). Results: The feasibility rate <strong>of</strong> ADCC measurement was 88%.<br />

ADCC basal values ranged between 30% and 100% (mean 62%, median<br />

66%). Basal ADCC was not influenced by patient gender. A tendency for an<br />

increased ADCC basal value was observed in younger patients: median was<br />

76% in the 6 patients � 60 vs 56% in the 23 patients over 60 years-old (p<br />

� 0.031). FCGR2A and FCGR3A gene polymorphisms were not linked to<br />

basal ADCC. The evolution <strong>of</strong> individual ADCC ability before treatment and<br />

2 months later revealed a significant drop in ADCC following treatment<br />

initiation (intra-patient comparison, n�18, p�0.006), with an absolute<br />

median drop <strong>of</strong> 19%. This decrease was not sustained over time and<br />

intra-patient comparison between basal value and 4-month measurement<br />

was not significant. 25 patients were assessable for survival (11 deaths).<br />

Basal ADCC values were not related to survival. Conclusions: A new<br />

generation <strong>of</strong> mAb is currently being developed with the aim to amplify<br />

ADCC. Present data illustrate the feasibility <strong>of</strong> ADCC measurement in<br />

mAb-treated patients and reveal an initial drop in ADCC under treatment<br />

that may reflect the variable chemotherapy-induced impact on host<br />

immunity.<br />

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