Phase I study of RO4929097, a gamma secretase inhibitor of Notch signaling, in patients with refractory metastatic or locally advanced solid tumors.

PURPOSE: To determine the maximum-tolerated dose (MTD) and assess safety, pharmacokinetics, pharmacodynamics, and evidence of antitumor activity of RO4929097, a gamma secretase inhibitor of Notch signaling in patients with advanced solid malignancies. PATIENTS AND METHODS: Patients received escalating doses of RO4929097 orally on two schedules: (A) 3 consecutive days per week for 2 weeks every 3 weeks; (B) 7 consecutive days every 3 weeks. To assess reversible CYP3A4 autoinduction, the expanded part of the study tested three dosing schedules: (B) as above; modified A, 3 consecutive d/wk for 3 weeks; and (C) continuous daily dosing. Positron emission tomography scans with [(18)F]fluorodeoxyglucose (FDG-PET) were used to assess tumor metabolic effects. RESULTS: Patients on schedule A (n = 58), B (n = 47), and C (n = 5; expanded cohort) received 302 cycles of RO4929097. Common grade 1 to 2 toxicities were fatigue, thrombocytopenia, fever, rash, chills, and anorexia. Transient grade 3 hypophosphatemia (dose-limiting toxicity, one patient) and grade 3 pruritus (two patients) were observed at 27 mg and 60 mg, respectively; transient grade 3 asthenia was observed on schedule A at 80 mg (one patient). Tumor responses included one partial response in a patient with colorectal adenocarcinoma with neuroendocrine features, one mixed response (stable disease) in a patient with sarcoma, and one nearly complete FDG-PET response in a patient with melanoma. Effect on CYP3A4 induction was observed. CONCLUSION: RO4929097 was well tolerated at 270 mg on schedule A and at 135 mg on schedule B; the safety of schedule C has not been fully evaluated. Further studies are warranted on the basis of a favorable safety profile and preliminary evidence of clinical antitumor activity.

Effect of ONCONASE +/- tamoxifen on ASPC-1 human pancreatic tumors in nude mice.

To evaluate changes in tumor physiological parameters after treatment with ONCONASE (ONC), we used laser Doppler flowmetery for tumor blood flow (TBF) in legs of nude mice bearing AsPC-1 human pancreatic carcinoma. Tumor interstitial fluid pressure (TIFP) was measured using the wick-in-needle technique, while intratumoral pO2 utilized O2 sensitive needle electrodes. TBF was significantly increased by an i.p. injection of ONC, then returned to the untreated levels at 150 min post-treatment. Single and multiple intraperitoneal injections of ONC significantly reduced TIFP (post-treatment at 1-7 days). ONC significantly improved tumor oxygenation evidenced by an increase in median pO2 from 4.2 mm Hg to 8.2 mm Hg. Since ONC had a synergistic interaction with tamoxifen (TAMX) on the cytotoxic clonogenicity of AsPC-1 tumor cells in vitro, we evaluated the antitumoral effects in vivo by ONC +/- TAMX, using nude mice bearing AsPC-1 pancreatic tumor cells of ascite (intraperitoneally implanted) or solid (subcutaneously implanted to legs) tumors. ONC alone effectively retarded the tumor growth, but TAMX alone did not. ONC + TAMX was synergistically effective in inhibiting tumor growth.

Entry into cells and selective degradation of tRNAs by a cytotoxic member of the RNase A family.

Onconase (P-30 protein), an enzyme in the ribonuclease A superfamily, exerts cytostatic, cytotoxic, and antiviral activity when added to the medium of growing mammalian cells. We find that onconase enters living mammalian cells and selectively cleaves tRNA with no detectable degradation of rRNA. The RNA specificity of onconase in vitro using reticulocyte lysate and purified RNA substrates indicates that proteins associated with rRNA protect the rRNA from the onconase ribonucleolytic action contributing to the cellular tRNA selectivity of onconase. The onconase-mediated tRNA degradation in cells appears to be accompanied by increased levels of tRNA turnover and induction of tRNA synthesis perhaps in response to the selective toxin-induced loss of tRNA. Degradation products of tRNA(3)(Lys), which acts as a primer for HIV-1 replication, were clearly detected in cells infected with HIV-1 and treated with sublethal concentrations of onconase. However, a new synthesis of tRNA(3)(Lys) also seemed to occur in these cells resulting in plateauing of the steady-state levels of this tRNA. We conclude that the degradation of tRNAs may be a primary factor in the cytotoxic activity of onconase.

Phase II trial of a single weekly intravenous dose of ranpirnase in patients with unresectable malignant mesothelioma.

PURPOSE: A multicenter phase II trial of ranpirnase (Onconase; Alfacell Corp, Bloomfield, NJ) as a single agent was conducted to further assess the safety and clinical efficacy of this novel antitumor ribonuclease. Patients with unresectable and histologically confirmed malignant mesothelioma (MM) were eligible. PATIENTS AND METHODS: One hundred five patients with Eastern Cooperative Oncology Group performance status 0 to 2 were enrolled onto the study. Thirty-seven percent of patients had not responded to prior chemotherapy. The primary end point of the study was survival. Tumor responses and time to progression were also assessed. The Cancer and Leukemia Group B (CALGB) prognostic group criteria were used to define a treatment target group (TTG). Both the intent-to-treat (ITT) and the TTG populations were analyzed for survival. RESULTS: Median survival times of 6 months for the ITT and 8.3 months for the TTG populations were observed. The 1- and 2-year survival rates were 34.3% and 21.6% for ITT, respectively, and 42% and 26.8% for TTG, respectively. Among the 81 patients assessable for tumor response, four had partial responses, two had minor regressions, and thirty-five experienced stabilization of previously progressive disease. Patients with responses and stable disease demonstrated markedly prolonged survival. Ranpirnase was well tolerated in the majority of patients, and there were no drug-related deaths. CONCLUSION: Ranpirnase demonstrated activity and a tolerable toxicity profile in patients with unresectable MM. The prognostic value of the CALGB groups was confirmed.