Clinical evaluation of ZD6474, an orally active inhibitor of VEGF and EGF receptor signaling, in patients with solid, malignant tumors

Original article

Annals of Oncology 16: 1391– 1397, 2005 doi:10.1093/annonc/mdi247 Published online 19 May 2005

Clinical evaluation of ZD6474, an orally active inhibitor of VEGF and EGF receptor signaling, in patients with solid, malignant tumors S. N. Holden1, S. G. Eckhardt1, R. Basser2, R. de Boer2, D. Rischin2, M. Green2, M. A. Rosenthal2, C. Wheeler3, A. Barge4 & H. I. Hurwitz5* 1

University of Colorado Cancer Center, Aurora, CO, USA; 2Cancer Trials Australia, Melbourne, Australia; 3Astra Zeneca, Boston, MA, USA; 4Astra Zeneca, Alderley Park, UK; 5Duke University Medical Centre, Durham, NC, USA

Received 12 March 2005; accepted 15 March 2005

Introduction Recognition of the role of angiogenesis as a fundamental requirement for tumor growth has led to the identification and assessment of a number of agents with antiangiogenic activity [1]. These agents block tumor vascular development principally by either preventing the binding of angiogenic growth factors to their receptors, or directly acting on endothelial cells to inhibit activation, proliferation or migration [2–4]. Vascular endothelial growth factor (VEGF) is one of the most potent stimulators of angiogenesis, inducing endothelial cell proliferation, protease expression, endothelial cell migration, capillary tube formation, and endothelial cell survival signaling in newly formed blood vessels [2, 5–8]. VEGF also plays a key role in regulating vascular permeability, with over-

*Correspondence to: Dr H. I. Hurwitz, Duke University Medical Centre, Box 3052, Durham, NC 27710, USA. Tel: +1-919-681-5257; Fax: +1-919-684-9712; E-mail: [email protected] q 2005 European Society for Medical Oncology

expression resulting in the highly permeable vessels characteristic of pathological neovasculature [9 –12]. Inhibition of VEGF signaling in tumor vasculature therefore represents an exciting therapeutic strategy, with the potential to arrest the development of new blood vessels essential for tumor growth and metastasis. Indeed, the clinical value of VEGF inhibition has been demonstrated in studies of bevacizumab which, in combination with chemotherapy, provided the first demonstration of clinically meaningful and statistically significant improvements in survival [13]. This agent has therefore established VEGF inhibition as an approach with major therapeutic potential. VEGF signaling occurs through the endothelial cell-associated tyrosine kinase receptors VEGFR-1 (Flt-1) and VEGFR-2 (KDR). However, activation of VEGFR-2 alone appears to be sufficient to induce the angiogenic and vascular permeabilization activity of VEGF. ZD6474 is a novel, orally available inhibitor of VEGFR-2 and epidermal growth factor receptor (EGFR) tyrosine kinase activity [14, 15]. Inhibition of VEGF

Downloaded from http://annonc.oxfordjournals.org/ at University of Georgia on June 17, 2015

Background: ZD6474 selectively inhibits the tyrosine kinase activity of vascular endothelial growth factor receptor and epidermal growth factor receptor. The safety, tolerability and pharmacokinetics of ZD6474 were assessed in a phase I dose-escalation study of patients with advanced solid tumors. Patients and methods: Adult patients with tumors refractory to standard treatments received oncedaily oral ZD6474 (50– 600 mg) in 28-day cycles, until disease progression or unacceptable toxicity was observed. Results: Seventy-seven patients were treated at doses of 50 mg (n = 9), 100 mg (n = 19), 200 mg (n = 8), 300 mg (n = 25), 500 mg (n = 8), and 600 mg (n = 8). Adverse events were generally mild, and the most common dose-limiting toxicities (DLT) were diarrhea (n = 4), hypertension (n = 4), and rash (n = 3). The incidence of most adverse events appeared to be dose-dependant. In the 500 mg/day cohort, 3/8 patients experienced DLT and this dose was therefore considered to exceed the maximum tolerated dose. Pharmacokinetic analysis confirmed that ZD6474 was suitable for once-daily oral dosing. Conclusions: Once-daily oral dosing of ZD6474 at 300 mg/day is generally well tolerated in patients with advanced solid tumors, and this dose is being investigated in phase II trials. Key words: anti-angiogenesis, dose escalation, pharmacokinetics, tolerability, ZD6474

1392 Single dose

Once-daily oral doses

7-day observation period PD or DLT

Cycle 0

Cycle 1

Cycle 2

Subsequent

(7 days)

(28 days)

(28 days)

28-day cycles

Figure 1. Study design. PD, progressive disease; DLT, dose-limiting toxicity.

Patients and methods Patients Adult patients with malignant tumors refractory to standard treatments, or for whom no standard treatment exists, were recruited from six centers in the USA and Australia. Subjects were required to have a WHO performance status of 0, 1 or 2, and a life expectancy of more than 12 weeks. The main exclusion criteria were significant cardiac, hematopoietic, hepatic or renal dysfunction; any gastrointestinal pathology that would affect drug bioavailability; a history of coagulopathy, central nervous system (CNS) tumors or metastases; and other anticancer therapy within the previous 4 weeks. Concomitant use of amiodarone, chlorpromazine, ketoconazole, itraconazole, troleandomycin, erythromycin, diltiazem, verapamil, phenytoin, carbamazepine, barbiturates, rifampicin or warfarin was not permitted. Patients in the expanded cohort phase were required to have only one active tumor type, measurable using Response Evaluation Criteria in Solid Tumors (RECIST) [19], and to have tumors suitable for MRI (magnetic resonance imaging; tumors considered suitable were those affecting soft tissue, liver, fixed pelvic masses or bone). All patients provided written informed consent. The trial was conducted in accordance with the Declaration of Helsinki, and was approved by all institutional ethics committees.

Study design Patients received a single oral dose of ZD6474 (50, 100, 200, 300, 500 or 600 mg), followed by a 7-day observation period (cycle 0; Figure 1). At the end of this period, patients received once-daily treatment at the same dose level as in cycle 0 for a total of 28 days (cycle 1). Patients received further 28-day cycles of treatment until evidence of tumor progression or dose-limiting toxicity (DLT) was observed. No intrapatient dose escalation was performed. Scheduled assessments were daily during cycle 0 and on days 1–15 of cycle 1, weekly during the remainder of cycles 1 and 2, and every 2 weeks for subsequent cycles. Dose escalation was performed when a minimum of three patients per cohort had completed 28 days of continuous treatment without experiencing DLT. Toxicity was graded according to the National Cancer Institute Common Toxicity Criteria (NCI-CTC) version 2.0. DLT was defined as grade 2 diarrhea daily for >7 days or grade 3 diarrhea for >24 h, despite maximum antidiarrheal support; grade 2 skin toxicity for >7 days affecting the patient’s subjective well being and requiring cessation of treatment, _ grade 3 that was not despite maximum supportive care; and any toxicity > clearly related to disease progression. Initially, dose escalation proceeded by two dose levels until two or more patients experienced a grade 2 toxicity, or one or more patients experienced a grade 3 toxicity. Thereafter, dose escalation proceeded by single-dose levels.

Expanded cohorts After recruitment was complete, an interim analysis of patients who had completed cycles 0 and 1 identified 500–600 mg/day as exceeding the maximum tolerated dose (MTD; defined as the dose of drug at which there is a 33% probability of experiencing toxicity within a 28-day cycle, which cannot be controlled by maximum supportive care). Therefore, 8–10 patients were evaluated sequentially at 100 and 300 mg dose levels in order to further characterize the safety, tolerability, and biological activity of ZD6474. Cycle 0 was omitted from the expansion phase of the study, with patients entering cycle 1 directly.

Safety and tolerability The primary study objective was to assess the safety and tolerability of escalating oral doses of ZD6474. Following full physical examination at enrolment, adverse events (AEs; defined as the development of a new medical condition or the deterioration of a pre-existing medical condition) were recorded at each scheduled assessment. Unless additional electrocardiograms (ECGs) were clinically indicated, 12-lead ECGs were performed at the screening visit (within 7 days of day 1), pre-treatment (cycle 1), at

Downloaded from http://annonc.oxfordjournals.org/ at University of Georgia on June 17, 2015

signaling responses by ZD6474 has been demonstrated in preclinical studies in vivo, including reversal of VEGFinduced hypertension [16]. Chronic once-daily administration of ZD6474 has been shown to result in significant tumor growth inhibition in a range of histologically diverse human xenograft models and to induce regression of established PC-3 prostate tumors [16]. Because ZD6474 inhibits the growth of gefitinib-resistant tumors in human xenografts, it may be a useful treatment in tumors that do not respond to EGF inhibitors [17]. An antimetastatic effect has also been demonstrated in a human pancreatic tumor model, showing a marked reduction in lymph node and liver metastases compared with control or gemcitabine-treated animals [18]. The primary objective of this phase I clinical study was to assess the safety and tolerability of oral ZD6474 in patients with advanced solid tumors. Secondary objectives included assessment of single- and multiple-dose pharmacokinetics and evaluation of the antitumor activity of ZD6474.

1393 the end of each 28-day cycle, and at the end of the study. QTc values were obtained using Bazett’s method of correction [20]. ZD6474 was _ 490 ms or QTc withheld if the following criteria were met: QTc > > _ 460 ms, with an increase from baseline of > _ 60 ms. Upon resolution of QTc prolongation, ZD6474 could be restarted at 50% of the initial dose. During cycle 0, vital signs were measured before dosing and 2, 4, 6, 8 and 10 h after dosing on day 1, and then every 24 h until day 3. During cycle 1, vital signs were measured before dosing and then daily for 14 days, after which measurements were taken weekly until the end of cycle 2. Following cycle 2, vital signs were measured once every 2 weeks. A chest X-ray was performed within 14 days of day 1 and as clinically indicated.

Pharmacokinetic assessment

of cycles 2 and 3 were used to assess the escalation to steady state for the daily dosing scheme. Population pharmacokinetic [21] and pharmacokinetic–pharmacodynamic [22] modeling was conducted using the population pharmacokinetic software NONMEM.

Tumor response Tumor response to ZD6474 therapy was evaluated according to RECIST _ 4 weeks [19]. Baseline radiological tumor assessments were performed < before the start of treatment. Clinical assessment was performed after every treatment cycle, and radiological assessment after every evennumbered cycle.

Biomarkers

Plasma concentrations of ZD6474 were determined using high performance liquid chromatography with tandem mass spectrometric detection. These data were used to calculate ZD6474 maximum concentration (Cmax), time to maximum concentration (tmax), terminal half-life (t12), area under the curve to infinity (AUC), and area under the curve to 24 h (AUC0 – 24) following the first dose in cycle 0, and Cmax, tmax, AUC0 – 24 and minimum concentration at steady state (Cmin) following multiple dosing in cycle 1. The plasma concentration data from the pre-dose samples collected on days 1 –14, 22, 28 and 29 of cycle 1 and on days 15 and 29

At one of the study sites, wound angiogenesis was evaluated in 10 patients using a previously reported model [23]. The wound angiogenesis results will be reported separately. Significant intra- and interpatient variability in image acquisition was seen in dynamic contrast-enhanced MRI within this study, precluding image analysis.

Statistical analyses No formal statistical analysis was performed on the safety, biological or pharmacokinetic data from this trial, as patients were enrolled sequentially rather than randomized to a particular dosage regimen. Sample size was based on practical considerations regarding the nature of the inclusion criteria. Safety data from both phases (dose escalation and cohort expansion) and from all cycles were combined. AEs were presented by starting dose, according to both the Medical Dictionary for Regulatory Activities (MedDRA) coding system and the CTC (version 2.0) grading system.

Table 1. Patient characteristics ZD6474 dosea (mg)

Total (n = 77)

50 (n = 9)

100 (n = 19)

200 (n = 8)

300 (n = 25)

500 (n = 8)

600 (n = 8)

Male

5

12

4

15

5

3

44

Female

4

7

4

10

3

5

33

Mean

61.8

56.6

45.6

57.7

51.6

50.6

55.3

Range

(48–78)

(28–75)

(31– 61)

(37–82)

(35–68)

(40–66)

(28–82)

6

4

8

2

0

23

Sex, n

Age, years

Primary tumor diagnosis, n Colorectal

3

Renal

0

2

1

0

0

0

3

Prostate

0

1

0

1

0

1

3

Melanoma

1

1

0

1

0

0

3

Liver

1

0

0

2

0

0

3

Head and neck

0

1

0

0

0

1

2

Mesothelioma

0

0

0

0

1

1

2

Otherb

4

8

3

13

5

5

38

c

Duration of ZD6474 treatment , days

a

Mean

55

119

81

76

88

24

80

Range

29–168

21–421

16–254

3–339

12– 186

9–40

3–421

Starting dose. Various other tumor types. c Number of days on dose. b

Downloaded from http://annonc.oxfordjournals.org/ at University of Georgia on June 17, 2015

During cycle 0, blood samples were collected before dosing and at 1, 2, 4, 6, 8 and 10 h after dosing on day 1, and then every 24 h until day 7. During cycle 1, blood samples were collected before dosing on days 1–14 and day 22, and before dosing and 2, 4, 6, 8, 10 and 24 h after dosing on day 28. Samples were also collected before dosing on days 15 and 29 of any subsequent cycles. Additional pre-dose samples were collected at each ECG assessment.

1394 Table 2. Number of patients who had an adverse event in any category ZD6474 dosea (mg)

Total (n = 77)

50 (n = 9)

100 (n = 19)

200 (n = 8)

300 (n = 25)

500 (n = 8)

600 (n = 8)

Any AE

9

18

8

25

8

8

76

CTC grade 3 or 4 AE

3

8

2

12

5

4

34

Drug-related CTC grade 3 or 4 AE

0

3

1

6

4

3

17

Withdrawals due to an AE

0

0

0

2

2

1

5

Death caused by any AE

0

0

0

1

0

0

1

a

Starting dose. AE, adverse event; CTC, Common Toxicity Criteria.

Patient characteristics Patient demographics and baseline characteristics were similar among dosage groups (Table 1). Of the 77 patients enrolled in the study, all were evaluated for safety and 67 were considered evaluable for efficacy. Ten patients were not eligible for evaluation by RECIST because they had no measurable lesions at baseline. The number of patients who had received previous chemotherapy or radiotherapy was 61 and 19, respectively. All but two patients withdrew from the study

Safety and tolerability Seventy-six patients had at least one AE, most occurring for the first time during the initial 28-day treatment period. The incidence of AEs in all categories is summarized in Table 2. The most common drug-related AEs were diarrhea (n = 29), rash (n = 26), nausea (n = 15), hypertension (n = 14), fatigue (n = 14), anorexia (n = 10), acneiform rash (n = 9),

Table 3. Drug-related adverse events classified as CTC grade 3 or 4 Adverse eventa

CTC gradeb ZD6474 dosec (mg)

Totald (n = 77)

100 (n = 19) 200 (n = 8) 300 (n = 25) 500 (n = 8) 600 (n = 8) Diarrhea (nos)

3

0

0

1

1

2

4

Hypertension (nos)

3

2

0

1

0

1

4

Rash (nos)

3

1

0

1

1

0

3

ALT increased

3

0

0

0

1

0

1

Colitis (nos)

3

0

0

0

0

1

1

Congestive cardiac failure

4

0

0

1

0

0

1

Deep vein thrombosis

3

0

0

1

0

0

1

Fatigue

3

0

0

0

0

1

1

Folliculitis

3

0

0

0

1

0

1

Hypophosphatemia

3

0

1

0

0

0

1

Intestinal ischemia

4

0

0

0

0

1

1

Intestinal obstruction (nos) 4

0

0

0

0

1

1

Pulmonary embolism

0

0

1

0

0

1

3

Photosensitive rash

3

0

0

1

0

0

1

Thrombocytopenia

3

0

0

0

0

1

1

a

Medical dictionary for regulatory activities (MedDRA) preferred term. Maximum CTC grade reported in any patient experiencing the adverse event specified. c Starting dose. d Total includes patients receiving 50 mg (n = 9), who did not experience any drug-related CTC grade 3 or 4 adverse events. ALT, alanine aminotransferase; CTC, Common Toxicity Criteria; nos, not otherwise specified. b

Downloaded from http://annonc.oxfordjournals.org/ at University of Georgia on June 17, 2015

by data cut-off, the main reasons for withdrawal being disease progression (n = 61), AE (n = 5) and withdrawal of informed consent (n = 3).

Results

1395 Table 4. Dose-limiting toxicities occurring during the first 35 days of treatment (cycles 0 and 1) ZD6474 dose

Center/Patient

Adverse eventa

CTC grade

200 mg

0002/0020

Hypophosphatemia

3

0003/0026

Diarrhea (nos)

2

300 mg

0001/0032

Rash (nos)

2

500 mg

0001/0039

Diarrhea (nos)

2

Folliculitis

2

0003/0036

ALT increased

3

0006/0041

Rash (nos)

3

0002/0045

Intestinal obstruction (nos)

3

Diarrhea (nos)

3

600 mg

3

Hypertension (nos)

3

0002/0046

Diarrhea (nos)

3

0003/0044

Fatigue

3

Thrombocytopenia

3

a

Medical dictionary for regulatory activities (MedDRA) preferred term. CTC, common toxicity criteria; ALT, alanine aminotransferase; nos, not otherwise specified.

Pharmacokinetic evaluation Plasma pharmacokinetic parameters revealed that absorption and elimination of ZD6474 after a single oral dose was slow, with median tmax ranging from 4.0 to 7.5 h and a t12 of  120 h (Table 5). Plasma concentration –time profiles following continuous oral dosing with 300 mg are shown in Figure 2. Trough levels indicated that a minimum of 28 days dosing is necessary to achieve steady-state plasma concentrations of ZD6474. Population pharmacokinetic analysis showed that the data was adequately described by a two-compartment model with

and maculopapular rash (n = 8). Drug-related AEs that led to treatment discontinuation were congestive cardiac failure, follicular rash, folliculitis and prolonged QT interval (all n = 1). Table 3 shows the most common drug-related AEs with CTC grade 3 or 4. There were 43 DLTs reported, 27 of which occurred during the dose-escalation phase and 16 during the cohort expansion phase. Most of the 14 DLTs reported within the first 35 days of the study (cycles 0 and 1) were at the 500

Table 5. Pharmacokinetic parameters of ZD6474 after a single dose (cycle 0) ZD6474 dosea (mg)

Parameter

50 (n = 8–10)

100 (n = 7–8)

200 (n = 6– 7)

300 (n = 6 –8)

500 (n = 6–7)

600 (n = 5–8)

Cmax (ng/ml), mean

19.7

58.1

102.9

213.3

346.6

635.8

CV (%)

54.3

73.0

71.8

40.4

70.1

76.8

tmax (h), median

5.5

6.5

7.0

7.5

6.0

4.0

Range

1–24

4– 24

1 –10

4–24

4–24

1–8

AUC0 – 24 (ng·h/ml), meanb

335

1056

1559

3019

5361

9587

CV (%)

43.4

58.0

47.4

43.6

67.4

63.9

AUC (ng·h/ml), meanb

1782

6067

9388

13 929

25 249

30 440

b

CV (%)

175.9

125.7

109.6

98.8

57.4

166.6

t12 (h), mean

133.8

104.7

124.4

109.2

96.2

89.8

SD

51.0

22.1

26.3

29.8

29.9

13.8

a

Starting dose. Geometric mean. AUC, area under the curve to infinity; AUC0 – 24, area under the curve to 24 h; Cmax, maximum concentration; CV, co-efficient of variation; tmax, time to maximum concentration; t12, terminal half-life. b

Downloaded from http://annonc.oxfordjournals.org/ at University of Georgia on June 17, 2015

Colitis (nos)

and 600 mg doses: three out of eight patients at each dose experienced four and seven DLTs, respectively (Table 4). Interim analysis of the dose-escalation phase determined the MTD of ZD6474 to be 500–600 mg; dose escalation had proceeded from 500 to 600 mg before a review of ECG data episodes showed asymptomatic QTc prolongation in the 500 mg (n = 2) and 600 mg (n = 1) cohorts, resulting in no further accrual at these doses per protocol. Consequently, 300 mg was the highest dose used during the cohort expansion phase of the study. Seven patients experienced QTc prolongation, although all occurrences were asymptomatic (n = 1 in the 100, 300 and 600 mg groups, and n = 2 in the 200 and 500 mg _ 300 mg, only two of these cases met groups). At doses < the predefined criteria for dose reduction, with both patients able to continue treatment at a lower dose of ZD6474 until withdrawal due to disease progression. Seven patients died while participating in this study and six of these deaths were considered to be disease-related. The remaining death was due to sepsis (subsequent to CTC grade 4 respiratory failure), with neither event considered by the investigator to be related to ZD6474 treatment.

1396

Mean ZD6474 plasma concentration (ng/ml)

10000

doses; the best overall response to treatment is summarized in Table 7. Median time to disease progression ranged from 56 to 218 days, with no apparent trend across doses.

Day 29

Day 1

1000 100

Discussion

10 1 0 1 2

4

8

24

10 Nominal time (hours)

Figure 2. Mean (±standard deviation) plasma concentrations of ZD6474 (ng/ml) in the 300 mg expanded cohort after a single dose (day 1) and multiple dosing for 28 days (day 29).

Tumor response No patients achieved an objective complete or partial response according to RECIST criteria. The percentage of patients with stable disease ranged from 12.5% to 50.0% across all ZD6474 Table 6. Population pharmacokinetic parameters from base model Parameter

Mean (% RSE)

95% CI

Inter-individual variability (%)

CL/F

8.47 l/h (11.9)

6.5– 10.4

49.8

Vc/F

1620 l (10.2)

1300– 1940

51.9

Vt/F Ka

1060 l (29.4)

448– 1670

80.9

0.476 h – 1 (29.3)

0.207– 0.745

109

Q/F

18.2 l/h (17.7)

11.9– 24.5

–

Lag time

0.801 h (11.0)

0.629– 0.973

–

CI, confidence interval; CL/F, oral clearance; Ka, absorption rate constant; Q/F, intercompartmental distribution rate; RSE, relative standard error; V/F, volume of distribution (Vc and Vt are the apparent volumes of the central and peripheral compartments, respectively).

Table 7. Best overall response to treatment with ZD6474 Best overall responsea

ZD6474 doseb (mg) 50

100

200

Total 300

500

600

(n = 77)

(n = 9) (n = 19) (n = 8) (n = 25) (n = 8) (n = 8) Partial or complete response

0

0

0

0

0

0

0

Stable disease

4

8

3

11

4

1

31

Disease progression

4

7

2

7

2

3

25

Not evaluable 1

4

3

7

2

4

21

a

Evaluated using RECIST. Starting dose.

b

Downloaded from http://annonc.oxfordjournals.org/ at University of Georgia on June 17, 2015

first-order absorption and a lag time. ZD6474 has a large volume of distribution (2680 l), low clearance (8.47 l/h) and slow absorption (Ka = 0.476 h 1), with a lag time of 0.801 h before the drug is detectable in plasma after oral administration (Table 6).

In this phase I study of patients with advanced solid tumors, daily oral ZD6474 was generally well tolerated at doses < _ 300 mg/day. Over an average of 11 weeks’ treatment (maximum 60 weeks), AEs were mostly mild and readily managed with supportive care/symptomatic treatment. The most common treatment-related AEs were diarrhea and rash, which appeared to be dose-related. Hypertension was also noted, although this did not appear to be related to dose or other pharmacokinetic parameters. Hypertension is likely to be a class effect for inhibitors of VEGF, having been observed in studies of bevacizumab, alone [24] and in combination with chemotherapy [13], as well as with several other VEGF inhibitors [25–27]. Any grade of drug-related hypertension was noted in 14 patients (18%); grade 3 hypertension (requiring the addition or modification of an oral anti-hypertensive regimen) was seen in four patients (5%) across all doses. There were no grade 4 hypertensive events or hypertensive crises. _ 500 mg were associated with an unacceptDoses of ZD6474 > able rate of DLTs, primarily diarrhea and rash, although these were readily manageable by dose interruption and reduction. These toxicities are likely related to the EGFR inhibitory effects of ZD6474. QTc prolongation was also noted in this study, but was not associated with any clinical sequelae, aside from prophylactic interruption or reduction of treatment doses per protocol. Potassium and magnesium depletion, which sometimes occur in the setting of treatment-related diarrhea, are known risk factors for QTc prolongation. For these reasons, close monitoring and repletion of electrolytes is advisable during ZD6474 treatment until further data are available. Future clinical studies are planned to better define the frequency of QTc prolongation and any associated risk factors. Pharmacokinetic assessment in this study has confirmed that ZD6474 is suitable for once-daily oral dosing. A minimum of 28 days continuous oral dosing with ZD6474 was required to achieve steady-state plasma concentrations, which is consistent with the long terminal half-life of  5 days. It is noteworthy that continuous once-daily dosing with 300 mg ZD6474 was sufficient to achieve concentrations greater than the IC50 for in vitro inhibition of VEGFR-2 tyrosine kinase activity (calculated using an in vitro IC50 = 19 ng/ml or 40 nM [16], and assuming  10% free drug in human plasma). Although several patients had stable disease, no objective partial or complete tumor responses were observed in this typically refractory phase I population. A number of angiogenesis inhibitors are currently in clinical development, including single- and multiple-targeted agents [1]. Although the therapeutic efficacy of targeting VEGF alone has been demonstrated with bevacizumab, targeting other processes essential for tumor growth and development has the potential for increasing antitumor activity with

1397

Acknowledgements Financial support was provided by AstraZeneca. The authors acknowledge editorial support from John Matthew, PhD.

References 1. Carmeliet P, Jain RK. Angiogenesis in cancer and other diseases. Nature 2000; 407: 249–257. 2. Ellis LM, Liu W, Fan F et al. Role of angiogenesis inhibitors in cancer treatment. Oncology 2001; 15: 39 –46. 3. Madhusudan S, Harris AL. Drug inhibition of angiogenesis. Curr Opin Pharmacol 2002; 2: 403 –414. 4. Scappaticci FA. Mechanisms and future directions for angiogenesisbased cancer therapies. J Clin Oncol 2002; 20: 3906–3927. 5. Risau W. Mechanisms of angiogenesis. Nature 1997; 386: 671–674. 6. Keck PJ, Hauser SD, Krivi G et al. Vascular permeability factor, an endothelial cell mitogen related to PDGF. Science 1989; 246: 1309–1312. 7. Lamoreaux WJ, Fitzgerald ME, Reiner A et al. Vascular endothelial growth factor increases release of gelatinase A and decreases release of tissue inhibitor of metalloproteinases by microvascular endothelial cells in vitro. Microvasc Res 1998; 55: 29–42. 8. Pepper MS, Montesano R, Mandriota SJ et al. Angiogenesis: a paradigm for balanced extracellular proteolysis during cell migration and morphogenesis. Enzyme Protein 1996; 49: 138–162. 9. Benjamin LE, Golijanin D, Itin A et al. Selective ablation of immature blood vessels in established human tumors follows vascular endothelial growth factor withdrawal. J Clin Invest 1999; 103: 159 –165. 10. Carmeliet P, Lampugnani MG, Moons L et al. Targeted deficiency or cytosolic truncation of the VE-cadherin gene in mice impairs VEGFmediated endothelial survival and angiogenesis. Cell 1999; 98: 147 –157. 11. Bates DO, Heald RI, Curry FE, Williams B. Vascular endothelial growth factor increases Rana vascular permeability and compliance by different signalling pathways. J Physiol 2001; 533: 263–272. 12. Dvorak HF, Detmar M, Claffey KP et al. Vascular permeability factor/vascular endothelial growth factor: an important mediator of angiogenesis in malignancy and inflammation. Int Arch Allergy Immunol 1995; 107: 233–235.

13. Hurwitz H, Fehrenbacher L, Novotny W et al. Bevacizumab plus irinotecan, fluorouracil, and leucovorin for metastatic colorectal cancer. N Engl J Med 2004; 350: 2335–2342. 14. Hennequin LF, Stokes ES, Thomas AP et al. Novel 4-anilinoquinazolines with C-7 basic side chains: design and structure activity relationship of a series of potent, orally active, VEGF receptor tyrosine kinase inhibitors. J Med Chem 2002; 45: 1300–1312. 15. Ciardiello F, Caputo R, Damiano V et al. Antitumor effects of ZD6474, a small molecule vascular endothelial growth factor receptor tyrosine kinase inhibitor, with additional activity against epidermal growth factor receptor tyrosine kinase. Clin Cancer Res 2003; 9: 1546–1556. 16. Wedge SR, Ogilvie DJ, Dukes M et al. ZD6474 inhibits vascular endothelial growth factor signaling, angiogenesis, and tumor growth following oral administration. Cancer Res 2002; 62: 4645–4655. 17. Ciardiello F, Bianco R, Caputo R et al. Antitumor activity of ZD6474, a vascular endothelial growth factor receptor tyrosine kinase inhibitor, in human cancer cells with acquired resistance to antiepidermal growth factor receptor therapy. Clin Cancer Res 2004; 10: 784–793. 18. Bruns CJ, Kohl G, Guba M et al. Anti-angiogenic and anti-tumor activity of a novel VEGFR-2 tyrosine kinase inhibitor ZD6474 in a metastatic human pancreatic tumor model. Proc Am Assoc Cancer Res 2003; 44: 604. 19. Therasse P. Response Evaluation Criteria in Solid Tumours. Eur J Cancer 2002; 38: 1817–1823. 20. Bazett HC. An analysis of the time-relations of electrocardiograms. Heart 1920; 7: 353 –370. 21. Beal SL, Sheiner LB. Estimating population kinetics. Crit Rev Biomed Eng 1982; 8: 195–222. 22. Mandema JW, Verotta D, Sheiner LB. Building population pharmacokinetic-pharmacodynamic models. I. Models for covariate effects. J Pharmacokinet Biopharm 1992; 20: 511 –528. 23. Lockhart AC, Braun RD, Yu D et al. Reduction of wound angiogenesis in patients treated with BMS-275291, a broad spectrum matrix metalloproteinase inhibitor. Clin Cancer Res 2003; 9: 586 –593. 24. Yang JC, Haworth L, Sherry RM et al. A randomized trial of bevacizumab, an anti-vascular endothelial growth factor antibody, for metastatic renal cancer. N Engl J Med 2003; 349: 427 –434. 25. Drevs J, Mross K, Medinger M et al. Phase I dose-escalation and pharmacokinetic (PK) study of the VEGF inhibitor PTK787/ZK222584 (PTK/ZK) in patients with liver metastases. Proc Am Soc Clin Oncol 2003; Abst 1142. 26. Raymond E, Faivre S, Vera K et al. Final results of a phase I and pharmacokinetic study of SU11248, a novel multi-target tyrosine kinase inhibitor, in patients with advanced cancers. Proc Am Soc Clin Oncol 2003; Abst 769. 27. Veronese ML, Flaherty KT, Townsend R et al. Pharmacodynamic study of the raf kinase inhibitor BAY 43-9006: Mechanisms of hypertension. Proc Am Soc Clin Oncol 2004; Abstr 2035. 28. Bruns CJ, Solorzano CC, Harbison MT et al. Blockade of the epidermal growth factor receptor signaling by a novel tyrosine kinase inhibitor leads to apoptosis of endothelial cells and therapy of human pancreatic carcinoma. Cancer Res 2000; 60: 2926– 2935. 29. Solorzano CC, Baker CH, Tsan R et al. Optimization for the blockade of epidermal growth factor receptor signaling for therapy of human pancreatic carcinoma. Clin Cancer Res 2001; 7: 2563–2572. 30. Kris MG, Natale RB, Herbst RS et al. Efficacy of gefitinib, an inhibitor of the epidermal growth factor receptor tyrosine kinase, in symptomatic patients with non-small cell lung cancer: a randomized trial. J Am Med Assoc 2003; 290: 2149–2158.

Downloaded from http://annonc.oxfordjournals.org/ at University of Georgia on June 17, 2015

minimal overlapping toxicities. In addition to being a potent inhibitor of VEGFR signaling, ZD6474 is also a submicromolar inhibitor of EGFR tyrosine kinase activity. ZD6474 may therefore provide added therapeutic benefit in tumors with EGFR-dependent proliferation or survival: EGFR inhibition has been shown to downregulate VEGF expression and tumor-related angiogenesis in preclinical models [28, 29], and selective inhibition of EGFR signaling has shown clinical benefit in advanced cancer patients [30]. Further evaluation of this activity is required, however, in order to better understand any potential benefits. In conclusion, once-daily oral administration of ZD6474 at _ 300 mg is well tolerated in patients with advanced doses < solid tumors. Phase II evaluation of ZD6474 in this dose range is ongoing in patients with a range of tumor types, both as monotherapy and in combination with certain other anticancer agents.