Krzysztof Appelt

Broad antitumor and antiangiogenic activities of AG3340, a potent and selective MMP inhibitor undergoing advanced oncology clinical trials.

ABSTRACT: We studied AG3340, a potent metalloproteinase (MMP) inhibitor with pM affinities for inhibiting gelatinases (MMP‐2 and ‐9), MT‐MMP‐1 (MMP‐14), and collagenase‐3 (MMP‐13) in many tumor models. AG3340 produced dose‐dependent pharmacokinetics and was well tolerated after intraperitoneal (i.p.) and oral dosing in mice. Across human tumor models, AG3340 produced profound tumor growth delays when dosing began early or late after tumor implantation, although all established tumor types did not respond to AG3340. A dose‐response relationship was explored in three models: COLO‐320DM colon, MV522 lung, and MDA‐MB‐435 breast. Dose‐dependent inhibitions of tumor growth (over 12.5‐200 mg/kg given twice daily, b.i.d.) were observed in the colon and lung models; and in a third (breast), maximal inhibitions were produced by the lowest dose of AG3340 (50 mg/kg, b.i.d.) that was tested. In another model, AG3340 (100 mg/kg, once daily, i.p.) markedly inhibited U87 glioma growth and increased animal survival. AG3340 also inhibited tumor growth and increased the survival of nude mice bearing androgen‐independent PC‐3 prostatic tumors. In a sixth model, KKLS gastric, AG3340 did not inhibit tumor growth but potentiated the efficacy of Taxol. Importantly, AG3340 markedly decreased tumor angiogenesis (as assessed by CD‐31 staining) and cell proliferation (as assessed by bromodeoxyuridine incorporation), and increased tumor necrosis and apoptosis (as assessed by hematoxylin and eosin and TUNEL staining). These effects were model dependent, but angiogenesis was commonly inhibited. AG3340 had a superior therapeutic index to the cytotoxic agents, carboplatin and Taxol, in the MV522 lung cancer model. In combination, AG3340 enhanced the efficacy of these cytotoxic agents without altering drug tolerance. Additionally, AG3340 decreased the number of murine melanoma (B16‐F10) lesions arising in the lung in an intravenous metastasis model when given in combination with carboplatin or Taxol. These studies directly support the use of AG3340 in front‐line combination chemotherapy in ongoing clinical trials in patients with advanced malignancies of the lung and prostate.

Rodent pharmacokinetic and anti-tumor efficacy studies with a series of synthetic inhibitors of matrix metalloproteinases

Matrix metalloproteinases are a family of zinc-containing proteases that degrade extracellular matrix and basement membranes. These enzymes are thought to play a role in processes essential for tumor growth, invasion, and metastasis. Here we report pharmacokinetic and anti-tumor efficacy studies with a series of structurally related inhibitors of these enzymes that were synthesized at Agouron Pharmaceuticals using protein structure based drug design. The compounds studied were AG3287, AG3293, AG3294, AG3296, AG3319, and AG3340. Rat oral bioavailability ranged from 15 to 68%. Despite similar profiles of enzyme inhibition across the family of enzymes, and similar pharmacokinetics following i.p. administration to mice, efficacy against the Lewis lung carcinoma murine model varied from tumor growth enhancement, to significant reductions in the size of primary tumors and the number of lung metastases. AG3340 was the most efficacious compound against the Lewis lung carcinoma model, resulting in the complete cessation of primary tumor growth throughout the experiment in 4/6 mice treated with daily i.p. injections at a dose of 50 mg/kg. This treatment inhibited the formation of lung metastases greater than 5 mm in diameter by 90%.

Efficacy of Prinomastat® (AG3340), a matrix metalloprotease inhibitor, in treatment of retinal neovascularization

Purpose. To study the activity of the novel anti-angiogenic compound AG3340 (Prinomastat ®) , a selective inhibitor of matrix metalloproteases, in an animal model of retinal neovascularization. Methods. C57BL/6J mice were used to produce oxygen-induced retinal neovascularization. Mice were exposed to room air from birth (P0) to postnatal 7 days (P7) and to hyperoxia (75% oxygen) for the next 5 days. On postnatal day 12 (P12) the animals were returned to the room air and were treated until postnatal day 16 (P16) with intraperitoneal injections of AG 3340. Four groups were assigned: no drug, 1.6 mg/kg/day, 16 mg/kg/day and 48 mg/kg/day. On day 17 (P17) the animals were sacrificed and the eyes prepared for histological sectioning. Preretinal neovascularization was assessed by counting neovascular nuclei of endothelial cells in the preretinal side of the internal limiting membrane (ILM). The use of animals for this study complies with the ARVO guidelines for animal research. Results. AG3340 administered systemically by intraperitoneal injections inhibited hypoxia-induced retinal neovascularization. The inhibition was dose dependent with highly significant decrease of neovascular nuclei counts among eyes treated with 0, 1.6 mg/kg, 16 mg/kg and 48 mg/kg doses. There appears to be a saturation effect of inhibition at the level of 70% at the two highest doses of 16 mg/kg and 48 mg/kg. Conclusions. AG3340 administered systemically significantly inhibits oxygen-induced retinal neovascularization in an animal model and appears to be a promising candidate for the treatment of neovascular retinal diseases.

The Effect of Prinomastat (AG3340), a Synthetic Inhibitor of Matrix Metalloproteinases, on Posttraumatic Proliferative Vitreoretinopathy

In a search for a pharmacologic adjuvant in the management of posttraumatic proliferative vitreoretinopathy (PVR), we investigated the effect of intravitreal injection of prinomastat (AG3340) on an experimental model. Posterior penetrating eye trauma was created in one eye each of 24 New Zealand white rabbits. One week after the surgery, all rabbits were randomized (1:1) to receive 0.5 mg prinomastat or the vehicle of the drug intravitreally every week for 6 weeks. The degree of PVR for each hemiretina was scored, and the two scores were summed to obtain a total eye score. The mean total eye score was 3.58 in the treatment group and 5.75 in the control group (p = 0.0307). The numbers of eyes with tractional retinal detachment in the prinomastat-treated (n = 12) and control (n = 12) groups were 3 and 9, respectively (p = 0.0391). These results suggest that intravitreally administered prinomastat has an inhibitory effect on posttraumatic PVR.

Antitumor efficacy of AG3340 associated with maintenance of minimum effective plasma concentrations and not total daily dose, exposure or peak plasma concentrations

Oral administration of AG3340, a novel metalloprotease (MMP) inhibitor, suppresses the growth of human colon adenocarcinoma (COLO-320DM) tumors in vivo (Proc Am Assoc Cancer Res 39: 2059, 1998). In this report, we tested the hypothesis that the growth inhibition of these tumors is associated with maintaining minimum effective plasma concentrations of AG3340. Nude mice were given a total oral daily dose of 25 or 200 mg/kg; 6.25 mg/kg was given four times per day (QID) (25 mg/kg/day), and 100 mg/kg was given in two daily doses (BID) (200 mg/kg/day). Peak plasma concentrations (Cmax) of 83 ± 43 (mean ± SD) and 1998 ± 642 ng/ml were detected 30 min after a single dose with 6.25 mg/kg and 100 mg/kg AG3340, respectively. AUC(0-24 h) values estimated from dosing with 25 and 200 mg/kg/day AG3340 were 672 and 10882 ng*h/ml, respectively. Importantly, both regimen inhibited tumor growth equivalently (74 to 82%). Efficacy was also compared at a total daily dose of 25 mg/kg by giving AG3340: QID (6.25 mg/kg per dose), BID (12.5 mg/kg per dose), and once daily (25 mg/kg per dose). The Cmax of these regimens was 83 ± 43, 287 ± 175 and 462 ± 495 ng/ml, respectively. AG3340 did not inhibit tumor growth with the latter two regimens. The efficacy of 6.25 mg/kg QID (25 mg/kg/day) was superior to the efficacy of 25 mg/kg BID (50 mg/kg/day), substantiating the independence of efficacy from the total daily dose and Cmax. Expectedly, peak to trough fluctuations were significantly smaller with the QID regimen than with BID and QD dosing. After 24 h, the trough was greater than 1 ng/ml with QID dosing but was less than 1 ng/ml after QD and BID dosing. These results suggest that the antitumor efficacy of AG3340 was associated with maintaining minimum effective plasma concentrations of AG3340 and demonstrate that the antitumor efficacy of AG3340 was independent of the total daily dose, peak plasma concentration, and drug exposure in this tumor model.

Evaluation of intraocular pharmacokinetics and toxicity of prinomastat (AG3340) in the rabbit.

To determine the ocular pharmacokinetics, physiological and histological effects of prinomastat (a matrix metalloprotease inhibitor), a total of seventy-seven eyes of New Zealand White rabbits received intravitreous and subtenon injections of prinomastat or of acidified water vehicle as control, Doses of 0.5 mg in 0.05 mL of prinomastat or acidified water were used for intravitreal injection. For the subtenon injections, doses of 5 mg prinomastat in 0.5 mL of acidified water were administered in the superotemporal quadrant. Intraocular pharmacokinetics were determined by analyzing vitreous samples at different postinjection time points using Liquid Chromatography-Mass Spectroscopy/Mass Spectroscopy (LC-MS/MS). The toxicity was evaluated by biomicroscopy, electroretinography (ERG), pneumatonometry, and histology. No toxicity was found with either administration method. At day 14 after intravitreal injection, levels of prinomastat in the vitreous and choroid were 1.4 ng/mg and 7.8 ng/mg, respectively. The retinal levels of prinomastat were 22 ng/mg at 24 hr and dropped below 1 ng/mg at 48 hr. Prinomastat remained well above minimum effective concentration in the choroid for at least four weeks after a single intravitreal injection, suggesting that local intravitreal injection may have potential in treating choroidal neovascularization.

The effect of prinomastat (AG3340), a synthetic inhibitor of matrix metalloproteinases, on uveal melanoma rabbit model

Purpose. We studied the effects of intravitreally administered prinomastat on the take rate and growth of uveal melanoma after xenograft implantation in rabbit uveal melanoma model. Methods. Uveal melanoma xenograft was implanted to suprachoroidal space in each eye of 24 pigmented rabbits which were immunosuppressed with cyclosporine. One week after surgery, the eyes were randomized to receive prinomastat or the vehicle of the prinomastat intravitreally every week for 4 weeks. The take rate of the xenograft, tumor height, apoptosis, and necrosis in the eyes which developed tumors from the treatment and control groups were compared. Results. A tumor mass was identified in 8 of 24 (33%) prinomastat-treated eyes and 20 of 24 (83%) of the vehicle-treated eyes. Echographic mesurements revealed a mean tumor height of 2.2 mm in the prinomastat-treated group and 3.8 mm in the control group in those eyes with take of tumor (p < 0.001). Stereomicroscopic measurements showed a mean tumor height of 1.9 mm in the treatment group and 3.9 mm in the control group (p < 0.001). The mean number of apoptotic nuclei detected per mm 2 of the histologic section in the non-necrotic tumor was 8.12 in the prinomastat-treated group and 0.57 in the control group (p < 0.001). Evaluation of the digital images in microscopic sections of the tumors on histologic slides revealed 29.6% necrosis in prinomastat-treated eyes as compared to 10.9% in vehicle-treated eyes (p =0.003). Conclusions. These results suggest that prinomastat treatment significantly reduces the take rate and the growth rate of xenograft in uveal melanoma rabbit model.