Caroline Clairmont

Pilot trial of genetically modified, attenuated Salmonella expressing the E. coli cytosine deaminase gene in refractory cancer patients.

We performed a pilot trial in refractory cancer patients to investigate the feasibility of intratumoral injection of TAPET-CD, an attenuated Salmonella bacterium expressing the E. coli cytosine deaminase gene. A total of three patients received three dose levels of TAPET-CD (3 × 106–3 × 107 CFU/m2) via intratumoral injection once every 28 days as long as progression of disease or intolerable toxicity was not observed. From days 4 to 14 of each 28 day cycle, patients also received 5-fluorocytosine (5-FC) at a dose of 100 mg/kg/day p.o. divided three times daily. Six cycles of treatment were administered. No significant adverse events clearly attributable to TAPET-CD were demonstrated. Two patients had intratumor evidence of bacterial colonization with TAPET-CD, which persisted for at least 15 days after initial injection. Conversion of 5-FC to 5-fluorouracil (5-FU) as a result of cytosine deaminase expression was demonstrated in these two patients. The tumor to plasma ratio of 5-FU for these two colonized patients was 3.0, demonstrating significantly increased levels of 5-FU at the site of TAPET-CD colonization and insignificant systemic spread of the bacteria. In contrast, the tumor to plasma ratio of 5-FU of the patient who did not show colonization of TAPET-CD was less than 1.0. These results support the principle that a Salmonella bacterium can be utilized as a delivery vehicle of the cytosine deaminase gene to malignant tissue and that the delivered gene is functional (i.e. able to convert 5-FC to 5-FU) at doses at or below 3 × 107 CFU/m2.

Phase I and pharmacokinetic study of the ribonucleotide reductase inhibitor, 3-aminopyridine-2-carboxaldehyde thiosemicarbazone, administered by 96-hour intravenous continuous infusion.

PURPOSE 3-aminopyridine-2-carboxaldehyde thiosemicarbazone (3-AP; Triapine; Vion Pharmaceuticals Inc, New Haven, CT) is a potent inhibitor of ribonucleotide reductase, with activity in preclinical tumor model systems. A phase I trial was initiated to determine the dose-limiting toxicities, maximum-tolerated dose, and pharmacokinetics of a 96-hour intravenous (IV) continuous infusion in patients with advanced cancer. PATIENTS AND METHODS Initially, courses were administered every 3 weeks, using an accelerated titration design. Subsequently, courses were administered every 2 weeks, and the dose was escalated in cohorts of three to six patients. RESULTS Twenty-one patients were enrolled, seven on the every-3-week schedule and 14 on the every-other-week schedule. Three of six patients at 160 mg/m(2)/d developed dose-limiting toxicities including neutropenia, hyperbilirubinemia, and nausea or vomiting. Based on these initial results, the dose for 3-AP was re-escalated beginning at 80 mg/m(2)/d but administered every 2 weeks. At 120 mg/m(2)/d, three of seven patients had dose-limiting but reversible asthenia, hyperbilirubinemia, and azotemia or acidosis; however, in the case of renal and hepatic adverse events, the events were related to pre-existing borderline abnormal organ function. Therefore, the recommended phase II dose for 3-AP administered by 96-hour IV infusion is 120 mg/m(2)/d every 2 weeks. Detailed pharmacokinetic studies demonstrated linear kinetics up to 160 mg/m(2), with substantial inter-patient variability. There was no correlation between dose and clearance (R(2) = 0.0137). There were no objective responses, but there was prolonged stabilization of disease or decreases in serum tumor markers associated with stable disease in four patients. CONCLUSION The 96-hour infusion of 3-AP is safe and well tolerated at the recommended phase II doses. Phase II trials of Triapine are ongoing.

A Phase I and Pharmacokinetic Study of VNP40101M, a Novel Sulfonylhydrazine Alkylating Agent, in Patients with Refractory Leukemia

Purpose: VNP40101M is a novel sulfonylhydrazine alkylating agent with broad antitumor activity in animal models. As alkylating agents are important antileukemia drugs, a Phase I and pharmacokinetic study of VNP40101M was conducted in patients with refractory or relapsed leukemias or poor-risk myelodysplastic syndromes (MDS). Experimental Design: VNP40101M was given as a single i.v. infusion over 15–70 min on day 1. Courses were repeated every 4 weeks according to antileukemic activity. The starting dose of 220 mg/m2 was escalated by ∼33% in cohorts of 3–6 patients until a maximum-tolerated dose was established. One additional cohort was treated with the maximum-tolerated dose divided over days 1 and 8. Results: Thirty-eight patients, including 28 with acute myeloid leukemia and 5 with MDS, received 52 courses of treatment. Nondose-limiting, reversible infusion-related toxicities were the most frequent adverse event, occurring in 24 (63%) patients on the first course. Dose escalation was terminated at 708 mg/m2 for prolonged myelosuppression in 1 of 7 patients, and 600 mg/m2 was selected as the recommended Phase II dose, with no significant extramedullary toxicity at this dose level. Two patients, 1 with MDS treated with 300 mg/m2 and 1 with acute myeloid leukemia treated with 600 mg/m2, achieved complete remission. Conclusions: VNP40101M had significant antileukemic activity and minimal extramedullary toxicity in patients with relapsed or refractory disease.

A phase I and pharmacokinetic study of VNP40101M, a new alkylating agent, in patients with advanced or metastatic cancer

SummaryPurpose: VNP40101M is a new alkylating agent that demonstrated broad anti-tumor activity in murine tumor models. A phase I trial was initiated to determine the toxicities, maximum tolerated dose, and pharmacokinetics of VNP40101M by short IV infusion. Study design: The starting dose was 3 mg/m2 every four weeks, and was escalated in successive cohorts as follows: 6, 12, 24, 40, 60, 80, and 100 mg/m2. Beyond 100 mg/m2, dose increments were 25%. Initially, 1–2 patients were assigned to a dose level. Intra-patient dose escalation was permitted. With the first instance of a drug-related ≥ grade 2 adverse event, all dose levels required assessment of 3–6 patients. Pharmacokinetic parameters were assessed in the first cycle and any cycle with a change in dose. Results: Twenty-six patients in 13 dose levels ranging from 3–305 mg/m2 were evaluated. Dose-related thrombocytopenia was the major toxicity, with the nadir occurring at a median of day 27. At 305 mg/m2, six of eight patients developed grade 3 thrombocytopenia, including one event that met the definition for DLT. Other dose-related toxicities included moderate granulocytopenia, anemia, and a mild infusion-related syndrome consisting of acute headache and facial flushing. The granulocyte nadir occurred at a median of day 34, and recovery of both thrombocytopenia and neutropenia to < grade 2 occurred at a median of day 43. VNP40101M peak plasma concentrations and AUC were linear with dose. The elimination half-life was short and estimated to be approximately 15 minutes. Conclusions: The MTD and recommended dose for phase II trials is 305 mg/m2 every six weeks. Phase II trials in less heavily pre-treated patient populations are warranted.

Comparative evaluation of the acute toxic effects in monkeys, pigs and mice of a genetically engineered Salmonella strain (VNP20009) being developed as an antitumor agent

The objective of these studies was to perform a comparative evaluation of the acute toxicity of VNP20009, a genetically engineered Salmonella strain, in monkeys, pigs, and mice. It is hypothesized that mice would be more susceptible than other animal species to the toxic effects of VNP20009, because mice are the most sensitive natural host for the parental wild-type Salmonella typhimurium strain. These studies also compared the virulence of VNP20009 and the parental Salmonella in mice. In Cynomolgus monkeys and Yorkshire pigs (n = 2/dose), various doses (expressed as colony forming units [cfu] per animal) of VNP20009, or vehicle, were administered as a single IV injection (∼ 1 ml/min). The body weight, body temperature, clinical signs, clinical pathology (serum chemistry and hematology), and ophthalmic examinations (only in monkeys) were evaluated at various times. Necropsy was performed on day 15 in the pigs, and necropsy and histopathology on days 8 or 15 in the monkeys. In C57BL/6 mice (n = 10/dose), various doses of VNP20009, or the parental Salmonella, were administered as a single IV bolus injection. The mice were observed daily over 3 weeks. The results from monkeys showed that VNP20009-related changes in clinical pathology were primarily confined to fiver enzymes and fiver function tests (i.e., cholesterol, triglyceride, alanine aminotransferase, and aspartate aminotransferase levels). Significant toxicological changes occurred only at the dose of 1 × 1010 cfu/monkey, but not at the doses of 1 × 108 or 3 × 109 cfu/monkey. Gross necropsy and histology findings were primarily confined to the spleen (enlargement, weight increase, and reticuloendothelial hyperplasia), thymus (size and weight reduction and lymphoid depletion), mesenteric lymph node (enlargement), and lung (weight increase). Most of these necropsy and microscopic findings, which occurred mostly in the high-dose group, may be related to the physiological responses to infection, rather than related to the intrinsic toxicity of VNP20009. The results from pigs showed that VNP20009 induced toxicological effects only at the dose of 3 × 109 cfu/pig, but not at the doses of 3 × 108 or 3 × 1010 cfu/pig. Both pigs treated with 3 × 1010 cfu/pig died within the first 2 days post-treatment. Necropsy showed the presence of abdominal transudate fluid, skin blotching, and pulmonary-and gall bladder-associated edema. Therefore, the pig mortality may have been related to the physical damage induced by the sudden systemic presence of large amounts of suspension. The results from mice showed that VNP20009, at doses as high as 1 × 106 cfu/mouse, did not induce any mortality. A 30% mortality rate was induced by 3 × 106 cfu/mouse, and 100% mortality by 1 × 107 cfu/mouse. The parental Salmonella, at a dose of 1 × 102 or 3 × 102 cfu/mouse, induced a 100% mortality. In conclusion, the doses of VNP20009 that induced acute toxicity are very high, suggesting that VNP20009 may be a safe agent. The virulence is 50,000 × less in VNP20009 than the parental Salmonella.