PURPOSE:Arg-D-Trp-NmePhe-D-Trp-Leu-Met-NH(2) (Antagonist G), a substance P (SP 6-11) analogue, inhibits mitogenesis stimulated by a broad spectrum of neuropeptides and has demonstrated antitumor activity in vitro and in vivo with IC(50) concentrations of 10-20 microM in small cell lung cancer and other cell lines. Because neuropeptides are part of complex neurohumoral pathways, we have sought to develop novel pharmacodynamic approaches as part of the early clinical development of this potential anticancer drug.EXPERIMENTAL DESIGN:A Phase I trial was performed in two stages. In stage 1, Antagonist G was administered at 3- week intervals using an accelerated dose-escalation strategy until the target maximum plasma concentration (C(max)) of 10 microM was achieved. In stage 2, dose intensity was increased to weekly, and the inhibitory effect of i.v. Antagonist G was assessed by forearm blood flow (FBF) using SP as a vasodilator, as measured by venous plethysmography.RESULTS:In stage 1, dose was escalated from 2 to 300 mg/m(2) in 12 dose levels using only 15 patients. In stage 2, nine patients were entered at three dose levels (300, 350, and 400 mg/m(2)) and a C(max) of 45 microM was achieved. Facial flushing was the only consistent toxicity but was not dose limiting. FBF studies demonstrated that Antagonist G consistently inhibited the vasodilatory effects of SP (mean, 62 +/- 2% inhibition).CONCLUSIONS:Antagonist G can be safely administered up to 400 mg/m(2), achieving C(max)s >20 microM by weekly 6-h i.v. infusion. FBF studies in patients demonstrated that Antagonist G inhibits SP vasodilatory effects in vivo at these doses in the absence of dose-limiting toxicity.

2-Amino-3,4-dihydro-6-methyl-4-oxo-5-(4-pyridylthio)-quinazoline dihydrochloride (nolatrexed dihydrochloride, Thymitaq, AG337), a specific inhibitor of thymidylate synthase, was developed using protein structure-based drug design. Intravenously administered nolatrexed is active clinically. As oral bioavailability is high (70–100%), nolatrexed was administered orally, 6 hourly for 10 days, at 3-week intervals, and dose escalated from 80 to 572 mg m–2day–1in 23 patients. Common toxicity criteria (CTC) grade 3 toxicities included nausea, vomiting, stomatitis and liver function test (LFT) abnormalities. Thrombocytopenia (grade 1 or 2) occurred at doses ≥ 318 mg m–2day–1and neutropenia (grade 2) at 429 and 572 mg m–2day–1. An erythematous maculopapular rash occurred at dosages ≥ 318 mg m–2day–1(7 out of 19 patients). LFT abnormalities occurred in two out of six patients (grade 3 or 4 bilirubin and grade 3 alanine transaminase) at 572 mg m–2day–1. Nolatrexed plasma concentrations 1 h after dosing were 6–16 μg ml–1, and trough 3–8 μg ml–1, at 572 mg m–2day–1. Inhibition of thymidylate synthase was demonstrated by elevation of plasma deoxyuridine. Six-hourly oral nolatrexed for 10 days was associated with antiproliferative effects, but nausea and vomiting was dose limiting at 572 mg m–2day–1. Nine patients were treated at 429 mg m–2day–1; three out of nine experienced grade 3 nausea, but 17 out of 22 treatment courses were completed (with the co-administration of prophylactic antiemetics) and this dose level could be considered for phase II testing.

The anthracenedione analogue, BBR 2778 is an active antitumour agent preclinically and has reduced potential for cardiotoxicity compared with other similar drugs in preclinical models. BBR 2778 was administered 3 weekly by a 1 h intravenous (i.v.) infusion to 24 patients and the dose escalated rapidly from 20 to 240 mg/m2. The dose-limiting toxicity (DLT) was neutropenia, common toxicity criteria (CTC) grade 4 in 3/5 patients at 240 mg/m2. Other toxicities ⩾CTC grade 3 were: vomiting, lymphopenia, thrombocytopenia and lethargy. Blue discoloration of veins and urine was also noted. In 1 patient (120 mg/m2, four cycles) left ventricular ejection reaction (LVEF) fell (CTC grade 2) but with no clinical sequelae. BBR 2778 plasma pharmacokinetics were biphasic (mean t1/2β at 180 mg/m2=14.1 h) and the urinary elimination of the unchanged drug was <10%. In a patient with previously treated small cell lung carcinoma (SCLC), a 49% reduction in measurable disease was noted with resolution of pericardial and pleural effusions (120 mg/m2×eight cycles). From the results of this phase I study a dose of 180 mg/m2 as a 1 h infusion every 3 weeks would be recommended for phase II trials.