An evaluation of the drug interaction potential of pazopanib, an oral vascular endothelial growth factor receptor tyrosine kinase inhibitor, using a modified Cooperstown 5+1 cocktail in patients with advanced solid tumors

Pazopanib, an oral inhibitor of vascular endothelial growth factor receptor, platelet-derived growth factor receptor, and c-kit kinases, inhibits multiple cytochrome P450 (CYP450) enzymes in vitro. This study in patients with advanced cancer evaluated the effect of pazopanib on CYP450 function by comparing the pharmacokinetics of CYP-specific probe drugs in the presence and absence of pazopanib. The probes used included midazolam (CYP3A specific), warfarin (CYP2C9 specific), omeprazole (CYP2C19 specific), caffeine (CYP1A2 specific), and dextromethorphan (CYP2D6 specific). The estimated ratios of the geometric means (90% confidence interval (CI)) for the area under the curve to the last measurable point (AUC(0-t)) for these probe drugs with/without pazopanib were as follows: midazolam, 1.35 (1.18-1.54); omeprazole, 0.81 (0.59-1.12); caffeine, 1.00 (0.77-1.30); and S-warfarin, 0.93 (0.84-1.03). The geometric least-squares (LS) mean ratio of urine dextromethorphan:dextrorphan ranged from 1.33 (0-4-h interval) to 1.64 (4-8-h interval). The data suggest that pazopanib is a weak inhibitor of CYP3A4 and CYP2D6 and has no effect on CYP1A2, CYP2C9, and CYP2C19 in patients with advanced cancer.

A phase I study of pazopanib in patients with advanced hepatocellular carcinoma

3561

Background: Patients (pts) with advanced hepatocellular carcinoma (HCC) have a poor prognosis. HCC is a highly vascular tumor with increased levels of angiogenic factors including VEGF and VEGFR. Pazopanib (GW786034) is an oral angiogenesis inhibitor targeting VEGFR, PDGFR, and c-Kit. A Phase I study was conducted to determine the maximum tolerated dose (MTD), safety, pharmacokinetics, pharmacodynamics and efficacy of pazopanib in patients with locally unresectable and/or advanced HCC. Methods: Eligibility criteria included unresectable and/or metastatic HCC with at least 1 target lesion, recovery from prior systemic regimens, ECOG PS 0 or 1, Child-Pugh A, and adequate organ function. Doses of pazopanib were escalated from 200 mg once daily (QD) to 800 mg QD in a 3 + 3 design. DCE- MRI was performed to assess changes in tumor permeability. Results: 27 Asian pts have been enrolled at QD doses of 200 (4 pts), 400 (10), 600 (8), 800 (5): median (range) age = 61 (38–76); M/F = 85%/15%; ECOG 0/1 = 59%/41%; 81% with metastatic disease; 67% with Stage IV; 22% with prior systemic therapy, 26% with prior TACE. Most common AEs were: diarrhea (59%; 4% Gr 3); hypertension (44%; 26% Gr 3), cough (19%); fatigue (19%; 4% Gr 3); and hair depigmentation (15%). Hepatobiliary lab abnormalities were: AST elevation (63%; 15% Gr 3), hyperbilirubinemia (63%; 4% Gr 3), ALT elevation (41%; 7% Gr 3), and Alk phos (37%; 4% Gr 3). DLTs were Gr 3 malaise (1 pt) and Gr 3 AST/ALT elevation (1 pt) at 800 mg. MTD was determined to be 600 mg QD. Median (range) days on study was 85 (4–663) overall; 106 days (4–274) at the MTD. Best response was PR in 2 pts (7%; 1 at 800mg, 1 at 600 mg) and SD > 4 mos in 11 pts (41%). Median TTP at the MTD was 137.5 days (4–280 days). Median % change in tumor permeability (Ktrans) following 3 weeks of pazopanib administration at the MTD (5 pts) was 45%. Predose and maximum plasma pazopanib concentrations at 800 mg QD were similar to values observed previously at the same dose. Conclusions: Pazopanib has a manageable safety profile in HCC at the MTD of 600mg QD. Preliminary evidence of antitumor activity was observed. Changes in tumor DCE-MRI parameters were seen following repeated dose pazopanib administration.

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Phase I study to determine tolerability and pharmacokinetics (PK) of SB-743921, a novel kinesin spindle protein (KSP) inhibitor

2000

Background: SB-743921, a potent and selective inhibitor of KSP (Ki =100 pM; >40,000-fold selectivity vs other kinesins), causes mitotic arrest, potent inhibition of tumor cell proliferation, and demonstrates activity in a broad range of human tumor xenografts. Methods: A phase I study was conducted to determine the maximum tolerated dose (MTD) and PK profile of SB-743921 when administered IV over 60 minutes every 21 (Q 21) days (d). Results: 44 patients (pts) (M/F 19/25), median age 61.5 yrs (range 32–80, with solid tumors were treated at doses of 2 (n=2), 4 (n=27), 5 (n=6), 6 (n=3), and 8 (n=6) mg/m2 (median cycles 2, range 1–10, total cycles 101). Frequent tumor types included colorectal (n=11), ovarian (n=5), NSCLC (n=5), esophageal (n=4), and pancreatic (n=4). Dose-limiting toxicities (DLTs) at 8 mg/m2 consisted of (max CTC grade/pt) prolonged grade (gr) 4 neutropenia (n=2), gr 3 elevated ALT/AST (n=1), and gr 3 elevated bilirubin (n=1). DLTs at 6 mg/m2 were gr 3 hyponatremia (n=1) and prolonged gr 4 neutropenia (n=1). DLTs at 5 mg/m2 were limited to febrile neutropenia (n=2). The 4 mg/m2 dose level was determined as the phase II dose. Toxicities at 4 mg/m2 included gr 1 fatigue (n=8) and neutropenia [gr 1 (n=4), gr 2 (n=7), gr 3 (n=3), gr 4 (n=2)]. Neutropenia nadir was day 6–8 with recovery to gr ≤2 by day 15. Gr 3 non-hematologic toxicities at 4 mg/m2 included gr 3 ALT (n=1), gr 3 AST (n=2), gr 3 hyperbilirubinemia (n=1), gr 3 hypophosphatemia (n=1), and gr 3 alkaline phosphatase elevation (n=1). Median PK values in cycle 1 at 4 mg/m2 were: Cmax 473 ng/ml, AUC0-∞ 5207 ng.hr/ml, and t½ 36 hr. AUC0-∞ and Cmax were proportional to dose. No consistent correlation was observed between DLTs and PK parameters. Stable disease for ≥ 4 cycles (range 4–11) was observed in 6 pts (4 pts at 4 mg/m2; 1 pt at 6 mg/m2; 1 pt at 8 mg/m2). A pt with cholangiocarcinoma had evidence of radiographic tumor regression (post cycle 10) and a >50% decrease in her CA 19–9. Conclusions: The recommended phase II dose of SB-743921 on the Q 21 day schedule is 4 mg/m2. The observed toxicities at the recommended phase II dose are manageable and reversible. The onset and duration of neutropenia is predictable.

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Phase II trial of iboctadekin (rhIL-18) on a daily X 5 schedule in metastatic melanoma (MM)

10043

Background: Interleukin-18 (IL-18) is an immunostimulatory cytokine with potent antitumor activity in preclinical models. Two phase I studies of recombinant human (rh) IL-18 explored a wide dose range (0.03–1.0 mg/kg) without reaching a maximum tolerated dose (MTD) on the daily × 5 schedule. Pharmacodynamic data including inflammatory cytokine production and activation of lymphocyte subsets revealed optimal biologic activity at the lower end of the dose range (0.01–0.2 mg/kg) as did 2 unconfirmed partial responses (PRs) in a MM and a renal cancer patient (pt) at 0.1 mg/kg. Methods: An open-label, randomized, phase II trial in 60 adult pts with previously untreated MM was conducted to evaluate the efficacy and safety of rhIL-18 administered as a 2-hour IV infusion daily × 5 every 28 days for 6 cycles. Pts with PS ≤ 1, without known CNS involvement, and with adequate end organ function were randomized in stage 1 to 3 dose levels of IL-18 stratified according to AJCC M stage 1a/b vs. 1c. Two confirmed responses for a given dose level in Stage 1 were required to enroll 20 additional pts/level in Stage 2. The 1° objective was determination of overall response rate (ORR) for each dose level. Progression-free survival (PFS), tolerability, and immunogenicity were 2° endpoints. Results: 64 pts were treated at 3 dose levels. Nine pts remain on study. One pt experienced a confirmed PR. Based on preliminary data, the difference in PFS 6 months (mos) was significant (p=0.03) for 0.01 vs 0.1 mg/kg. Most common toxicities were mild to moderate fever, rigors, chills, n/v, and headache. Anti-IL18 antibody (Ab) development correlated with dose level. No clinically significant adverse events were associated with Ab development. Conclusion: Iboctadekin has an acceptable tolerability profile and has activity in MM but insufficient confirmed responses have been observed at this time to initiate Stage 2. Preliminary PFS 6 months indicates an advantage for pts treated at the lowest dose.

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Phase I study of ispinesib in combination with carboplatin in patients with advanced solid tumors

2027

Background: Kinesin spindle protein (KSP) is required for establishment of mitotic spindle bipolarity and cell cycle progression. Ispinesib (SB-715992), a KSP inhibitor, blocks assembly of a functional mitotic spindle leading to G2/M arrest. Carboplatin is a platinum compound that produces predominantly interstrand DNA cross-links. In vivo combination of a platinum-containing agent (cisplatin) and ispinesib resulted in synergistic activity and an increase in maximum tolerated dose (MTD) of ispinesib. In a phase I study of single agent ispinesib on a once every 21-day schedule, the MTD was 18 mg/m2 with prolonged gr 4 neutropenia and febrile neutropenia as DLTs. Methods: Patients (pts) with advanced solid tumors, PS ≤ 1, and ≤ 3 prior chemotherapy regimens were eligible for this study. Escalating doses of carboplatin (AUC 4-6) were administered over 30 minutes followed by a 1-hour infusion of escalating doses of ispinesib (9– 21 mg/m2) on a 21-day schedule. At least 3 pts were treated at each dose level. The primary objectives of this study included characterizing safety and tolerability and defining the optimally tolerated regimen (OTR). Limited pharmacokinetic (PK) samples were obtained. Clinical response assessments per RECIST criteria were performed every 2 cycles. Results: 24 pts [15 M/9 F; median age 63yrs, ECOG PS 1], were treated at 6 dose levels. The most common tumor types were prostate (7) and breast (4). A median of 3 cycles were administered (range 1–7; total 75 cycles). In 17 pts, the most common toxicities were (# pts, [grade]): nausea (10, Gr 1–2), vomiting (8, Gr 1–3), fatigue (8, Gr 1–2), neutropenia (8, Gr 2–4), anemia (7, Gr 1–3), and thrombocytopenia (7, Gr 1–4). Gr 4 thrombocytopenia was the observed DLT in 2 pts [ispinesib (mg/m2)/carboplatin (mg/ml·min) (# pts): 15/6 (1); 18/6 (1). PK assessment of ispinesib and carboplatin will be completed when the OTR has been defined. Unconfirmed minor responses have been observed in 3 pts (breast, prostate, NSCLC) starting at doses of 18/6. Conclusions: Determination of an OTR is ongoing. Ispinesib doses ≥ single agent MTD when combined with carboplatin AUC 6 have an acceptable tolerability profile and demonstrate preliminary evidence of anti-tumor activity.

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Effect of irradiation on cytokine production, MHC antigen expression, and vaccine potential of interleukin-2 and interferon-gamma gene-modified melanoma cells

Recent studies have shown that tumor cells transduced with interleukin-2 (IL-2) or interferon-gamma (IFN-gamma) genes stimulated a potent and specific antitumor immunity in experimental animals. For use as a human vaccine, tumor cells must be inactivated by irradiation to ensure the arrest of their growth. This study was undertaken to examine the effects of irradiation (10,000 rad) on the growth characteristics and vaccine potential of IL-2 and IFN-gamma-modified human melanomas and B16 murine melanoma. Irradiation caused cessation of cell growth and gradual reduction of cell number. Irradiated melanoma cells displayed 1.5 to 10-fold increases in the surface expression of MHC class I and/or class II antigens. The increases in MHC antigens persisted for 7-14 days postirradiation and then declined thereafter. Furthermore, IL-2- and IFN-gamma-transduced melanoma cells showed enhanced expression of the cytokine mRNA and increased cytokine secretion after irradiation. The effect of irradiation on the vaccine potential of the transduced cells was examined in C57BL/ 6 mice by prophylactic immunization and immunotherapy, and in nude mice by mixed transplantation assays. The irradiated, cytokine-transduced B16 cell vaccine was as or more effective than the unirradiated vaccine. These irradiated vaccines protected the animals against a challenging tumorigenic dose of B16 parental cells and suppressed the growth of 4-day-established B16 lung metastases. The ability of the irradiated IL-2-transduced human melanomas to inhibit the growth of admixed parental melanoma cells was retained but was less efficacious than unirradiated cells. The results suggest that irradiation does not abrogate the vaccine potential of IL-2- and IFN-gamma-transduced melanomas. These findings have implications for designing specific active immunotherapy protocols utilizing cytokine gene-modified tumor cells.

Immunological memory induced by genetically transduced tumor cells

BACKGROUND

Recent studies have demonstrated the usefulness of gene-modified tumor cells for immunotherapy. Using the tumorigenic murine fibrosarcoma, MCA 106, we investigated the effects of localized interferon-gamma (IFNg) secretion on tumorigenicity and on long-term memory.

METHODS

The murine IFNg (MuIFNg) gene was introduced into tumor cells. High and low IFNg-secreting clones were isolated. C57BL/6 mice were injected subcutaneously (s.c.) with either parental (P), high or low IFNg-secreting (H- or L-IFNg) cells, and tumor growth was assessed weekly. Spleens were harvested on different days postinjection (p.i.) to assess in vitro cytolytic activity. In parallel, tissues from injection sites were stained with macrophage-, CD4-, and CD8-detecting antibodies. Mice were injected s.c. with H-IFNg MCA106 tumor. After 150 days the animals were rechallenged s.c. with MCA106P in one leg and with irrelevant syngeneic tumor in the other.

RESULTS

Both P- and L-IFNg cells had similar growth, whereas the H-IFNg cells never grew. Only splenocytes from the H-IFNg animals showed in vitro CTL activity persisting until day 30 p.i. Histological data revealed a macrophage and CD4+ infiltrate much earlier in the H-IFNg group compared with the P group. Only the irrelevant, syngeneic tumor grew in animals previously injected with H-IFNg cells, whereas both P and irrelevant syngeneic tumors grew in controls.

CONCLUSIONS

Transduction of MCA106 cells with the MuIFNg gene diminished in vivo tumorigenicity in proportion to the amount of IFNg secreted. Immunization with H-IFNg cells elicited a host response characterized by macrophages and CD4+ cells. Long-term tumor-specific memory was seen after immunization with H-IFNg cells.