Ann Cahill

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.

Cloretazine (VNP40101M), a Novel Sulfonylhydrazine Alkylating Agent, in Patients Age 60 Years or Older With Previously Untreated Acute Myeloid Leukemia

PURPOSE Cloretazine (VNP40101M) is a sulfonylhydrazine alkylating agent with significant antileukemia activity. A multicenter phase II study of cloretazine was conducted in patients 60 years of age or older with previously untreated acute myeloid leukemia (AML) or high-risk myelodysplastic syndrome (MDS). PATIENTS AND METHODS Cloretazine 600 mg/m2 was administered as a single intravenous infusion. Patients were stratified by age, performance score, cytogenetic risk category, type of AML, and comorbidity. RESULTS One hundred four patients, median age 72 years (range, 60 to 84 years), were treated on study. Performance status was 2 in 31 patients (30%) and no patient had a favorable karyotype. Forty-seven patients (45%) had cardiac disease, 25 patients (24%) had hepatic disease, and 19 patients (18%) had pulmonary disease, defined as per the Hematopoietic Cell Transplantation-Specific Comorbidity Index, at study entry. The overall response rate was 32%, with 29 patients (28%) achieving complete response (CR) and four patients (4%) achieving CR with incomplete platelet recovery. Response rates in 44 de novo AML patients, 45 secondary AML patients, and 15 high-risk MDS patients were 50%, 11%, and 40%, respectively. Response by cytogenetic risk category was 39% in 56 patients with intermediate cytogenetic risk and 24% in 46 patients with unfavorable cytogenetic risk. Nineteen (18%) patients died within 30 days of receiving cloretazine therapy. Median overall survival was 94 days, with a 1-year survival of 14%; the median duration of survival was 147 days, with a 1-year survival of 28% for those who achieved CR. CONCLUSION Cloretazine has significant activity and modest extramedullary toxicity in elderly patients with AML or high-risk MDS. Response rates remain consistent despite increasing age and comorbidity.

Phase I and pharmacodynamic study of Triapine®, a novel ribonucleotide reductase inhibitor, in patients with advanced leukemia

In a phase I study, 24 patients with refractory leukemia received Triapine, a novel ribonucleotide reductase (RR) inhibitor, as a continuous intravenous infusion over 96 h beginning on days 1 and 15 or days 1 and 8. On the days 1 and 15 regimen, the starting dose was 120 mg/m(2) per day, and the maximum tolerated dose (MTD) was 160 mg/m(2) per day. Three of eight patients receiving 160 mg/m(2) per day in the first course, and one patient escalated to this dose in a second course, developed hepatic dose-limiting toxicity (DLT). For the days 1 and 8 regimen, the first 96 h infusion was administered at a fixed dose of 140 mg/m(2) per day. The dose of the second infusion beginning on day 8 was escalated from 120 to 160 mg/m(2) per day without observing DLT. No objective responses occurred. Over 70% of patients had a >50% reduction in white blood cell counts. The steady-state levels of Triapine were between 0.6 and 1 microM. As expected from the in vitro studies, at these plasma concentrations there was a decline in dATP and dGTP pools and a decrease in DNA synthetic capacity of the circulating leukemia cells. Based on these clinical, pharmacokinetic, and pharmacodynamic data, Triapine warrants further study in patients with hematologic malignancies.

Single-Agent Laromustine, A Novel Alkylating Agent, Has Significant Activity in Older Patients With Previously Untreated Poor-Risk Acute Myeloid Leukemia

PURPOSE An international phase II study of laromustine (VNP40101M), a sulfonylhydrazine alkylating agent, was conducted in patients age 60 years or older with previously untreated poor-risk acute myeloid leukemia (AML). PATIENTS AND METHODS Laromustine 600 mg/m(2) was administered as a single 60-minute intravenous infusion. Patients were age 70 years or older or 60 years or older with at least one additional risk factor-unfavorable AML karyotype, Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 2, and/or cardiac, pulmonary, or hepatic comorbidities. Results Eighty-five patients (median age, 72 years; range, 60 to 87 years) were treated. Poor-risk features included age 70 years or older, 78%; adverse karyotype, 47%; PS of 2, 41%; pulmonary disease, 77%; cardiac disease, 73%; and hepatic disease, 3%. Ninety-six percent of patients had at least two risk factors, and 39% had at least four risk factors. The overall response rate (ORR) was 32%, with 20 patients (23%) achieving complete response (CR) and seven (8%) achieving CR with incomplete platelet recovery (CRp). ORR was 20% in patients with adverse cytogenetics; 32% in those age 70 years or older; 32% in those with PS of 2; 32% in patients with baseline pulmonary dysfunction; 34% in patients with baseline cardiac dysfunction; and 27% in 33 patients with at least four risk factors. Twelve (14%) patients died within 30 days of receiving laromustine therapy. Median overall survival was 3.2 months, with a 1-year survival of 21%; the median duration of survival for those who achieved CR/CRp was 12.4 months, with a 1-year survival of 52%. CONCLUSION Laromustine has significant single-agent activity in elderly patients with poor-risk AML. Adverse events are predominantly myelosuppressive or respiratory. Response rates are consistent across a spectrum of poor-risk features.

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.

Phase 3 randomized, placebo-controlled, double-blind study of high-dose continuous infusion cytarabine alone or with laromustine (VNP40101M) in patients with acute myeloid leukemia in first relapse

Laromustine is a sulfonylhdrazine alkylator with significant antileukemia activity. An international, randomized (2:1), double-blind, placebo-controlled study was conducted to compare complete remission (CR) rates and overall survival (OS) in patients with first relapse acute myeloid leukemia (AML) treated with laromustine and high-dose cytarabine (HDAC) versus HDAC/placebo. Patients received 1.5 g/m(2) per day cytarabine continuous infusion for 3 days and laromustine 600 mg/m(2) (n = 177) or placebo (n = 86) on day 2. Patients in CR received consolidation with laromustine/HDAC or HDAC/placebo as per initial randomization. After interim analysis at 50% enrollment, the Data Safety Monitoring Board (DSMB) expressed concern that any advantage in CR would be compromised by the observed on-study mortality, and enrollment was held. The CR rate was significantly higher for the laromustine/HDAC group (35% vs 19%, P = .005). However, the 30-day mortality rate and median progression-free survival were significantly worse in this group compared with HDAC/placebo (11% vs 2%; P = .016; 54 days vs 34; P = .002). OS and median response durations were similar in both groups. Laromustine/HDAC induced significantly more CR than HDAC/placebo, but OS was not improved due to mortality associated with myelosuppression and its sequelae. The DSMB subsequently approved a revised protocol with laromustine dose reduction and recombinant growth factor support. The study was registered as NCT00112554 at http://www.clinicaltrials.gov.

Phase I Study of Cloretazine (VNP40101M), a Novel Sulfonylhydrazine Alkylating Agent, Combined with Cytarabine in Patients with Refractory Leukemia

Purpose: Cloretazine (VNP40101M) is a novel sulfonylhydrazine alkylating agent with significant antileukemia activity. A phase I study of cloretazine combined with cytarabine (1-β-d-arabinofuranosylcytosine, ara-C) was conducted in patients with refractory disease. Design: Ara-C was given i.v. at a fixed dose of 1.5 gm/m2/d by continuous infusion for 4 days (patients ages <65 years at time of diagnosis) or 3 days (patients ages ≥65 years). Cloretazine was given i.v. over 15 to 60 minutes on day 2 at a starting dose of 200 mg/m2, with escalation in 100 mg/m2 increments in cohorts of three to six patients until a maximum tolerated dose was established. The DNA repair enzyme O6-alkylguanine DNA alkyltransferase (AGT) was measured at baseline. Results: Forty patients, including 32 with acute myeloid leukemia, received 47 courses of treatment. Complete responses were seen at cloretazine dose levels of ≥400 mg/m2 in 10 of 37 (27%) evaluable patients, and in this patient subset, AGT activity was significantly lower in patients that responded to treatment than in patients who did not (P ≤ 0.027). Dose-limiting toxicities (gastrointestinal and myelosuppression) were seen with 500 and 600 mg/m2 of cloretazine combined with the 4-day ara-C schedule but not seen with the 3-day schedule. Conclusion: The recommended cloretazine dose schedule for future studies is 600 mg/m2 combined with 1.5 gm/m2/d continuous infusion of ara-C for 3 days. The cloretazine and ara-C regimen has significant antileukemic activity. AGT activity may be a predictor of response to cloretazine.

Phase II study of Cloretazine for the treatment of adults with recurrent glioblastoma multiforme

Cloretazine (VNP40101M) is a newly synthesized alkylating agent belonging to a novel class of alkylating agents called 1,2-bis(sulfonyl)hydrazines. Agents that belong to this class do not produce vinylating and chloroethylating species, and hence this class of alkylating agents is thought to have minimal systemic toxicity. Cloretazine produces two short-lived active species: 1,2-bis(methylsulfonyl)-1-(2-chloroethyl) hydrazine (a chloroethylating species) and a thiophilic carbamoylating methylisocyanate species. The chloroethylating species preferentially produces lesions at the O(6) position of guanine. The methylisocyanate species may inhibit O(6)-alkylguanine-DNA alkyltransferase, an important mechanism of resistance against alkylating agents. The purpose of this study was to determine the efficacy and tolerability of Cloretazine in patients with recurrent glioblastoma multiforme. The basis for the determination of efficacy was the proportion of patients alive without evidence of disease progression six months after initiation of treatment. Patients with recurrent glioblastoma multiforme received Cloretazine (300 mg/m(2)) intravenously every six weeks. Radiographic response, survival data, and toxicity were assessed. Thirty-two patients were enrolled. Median age was 56 years; 24 patients (75%) were men. At six months, two patients were alive and progression free, so the six-month progression-free survival (PFS) was 6%. The median PFS was 6.3 weeks. There were no objective radiographic responses. Twelve patients had stable disease for at least one cycle, but only two patients received more than three cycles. Nine patients experienced grade 4 thrombocytopenia and three patients experienced grade 4 neutropenia. Cloretazine administered every six weeks was relatively well tolerated, although this schedule has insignificant activity for patients with recurrent glioblastoma multiforme.

Phase I Study of Temozolomide and Laromustine (VNP40101M) in Patients With Relapsed or Refractory Leukemia

PURPOSE Although alkylators are known to be effective against some myeloid leukemias, resistance is often mediated via O6-alkylguanine-DNA alkyltransferase (AGT). Temozolomides inhibition of AGT may sensitize leukemia cells to the novel alkylator laromustine. We conducted a phase I translational study to evaluate the toxicities and estimate the maximum tolerated dose (MTD) of laromustine when administered with temozolomide (TMZ) in patients with hematologic malignancies. PATIENTS AND METHODS TMZ was delivered twice daily for 5 doses followed by a single infusion of laromustine. The target TMZ dose was the dose that would reliably result in > 90% AGT depletion. Once the target TMZ dose was identified, the laromustine dose was escalated. A total of 35 patients with relapsed/refractory leukemia were treated. RESULTS Treatment with TMZ 300 mg for 5 doses resulted in > 90% depletion of AGT levels in 5 of 6 patients. The MTD of the combination was established at TMZ 1500 mg and laromustine 300 mg/m2. Three of the 7 patients assayed from cohort 1 achieved > 90% depletion of AGT activity (range, 77%-100% depletion; median, 88%). Five of 6 patients enrolled in cohort 2 achieved > 90% depletion of AGT activity (range, 92%-100% depletion; median, 93.5%). This established that the 300-mg dose of TMZ (1500 mg total) would be maintained in subsequent cohorts. The majority of adverse events were primarily hematologic, with infectious and pulmonary complications also noted. Three (9%) of the patients with previous refractory disease achieved a complete remission, and 5 (14%) of the patients achieved a morphologic, leukemia-free, but persistent hypocellular bone marrow status. CONCLUSION Laromustine in combination with TMZ is tolerable and manageable at doses that predictably suppress AGT. Reliable TMZ-induced inhibition of AGT was observed in doses that are clinically tolerable. Evidence of antitumor effect was observed with this combination, suggesting that further efficacy studies should be performed.