Clofarabine plus cytarabine compared with cytarabine alone in older patients with relapsed or refractory acute myelogenous leukemia: results from the CLASSIC I Trial.

PURPOSE: To compare the receipt of clofarabine plus cytarabine (Clo+Ara-C arm) with cytarabine (Ara-C arm) in patients ≥ 55 years old with refractory or relapsed acute myelogenous leukemia (AML). PATIENTS AND METHODS: Patients were randomly assigned to receive either clofarabine (Clo) 40 mg/m(2) or a placebo followed by Ara-C 1 g/m(2) for five consecutive days. The primary end point was overall survival (OS). Secondary end points included event-free survival (EFS), 4-month EFS, overall remission rate (ORR; complete remission [CR] plus CR with incomplete peripheral blood count recovery), disease-free survival (DFS), duration of remission (DOR), and safety. RESULTS: Among 320 patients with confirmed AML (median age, 67 years), the median OS was 6.6 months in the Clo+Ara-C arm and 6.3 months in the Ara-C arm (hazard ratio [HR], 1.00; 95% CI, 0.78 to 1.28; P = 1.00). The ORR was 46.9% in the Clo+Ara-C arm (35.2% CR) versus 22.9% in the Ara-C arm (17.8% CR; P < .01). EFS (HR: 0.63; 95% CI, 0.49 to 0.80; P < .01) and 4-month EFS (37.7% v 16.6%; P < .01) favored the Clo+Ara-C arm compared with Ara-C arm, respectively. DFS and DOR were similar in both arms. Overall 30-day mortality was 16% and 5% for CLO+Ara-C and Ara-C arms, respectively. In the Clo+Ara-C and Ara-C arms, the most common grade 3 to 4 toxicities were febrile neutropenia (47% v 35%, respectively), hypokalemia (18% v 11%, respectively), thrombocytopenia (16% v 17%, respectively), pneumonia (14% v 10%, respectively), anemia (13% v 0%, respectively), neutropenia (11% v 9%, respectively), increased AST (11% v 2%, respectively), and increased ALT (10% v 3%, respectively). CONCLUSION: Although the primary end point of OS did not differ between arms, Clo+Ara-C significantly improved response rates and EFS. Study follow-up continues, and the role of clofarabine in the treatment of adult patients with AML continues to be investigated.

The chemosensitizing activity of inhibitors of glucosylceramide synthase is mediated primarily through modulation of P-gp function.

Glucosylceramide synthase (GCS) is a key enzyme engaged in the biosynthesis of glycosphingolipids and in regulating ceramide metabolism. Studies exploring alterations in GCS activity suggest that the glycolase may have a role in chemosensitizing tumor cells to various cancer drugs. The chemosensitizing effect of inhibitors of GCS (e.g. PDMP and selected analogues) has been observed with a variety of tumor cells leading to the proposal that the sensitizing activity of GCS inhibitors is primarily through increases in intracellular ceramide leading to induction of apoptosis. The current study examined the chemosensitizing activity of the novel GCS inhibitor, Genz-123346 in cell culture. Exposure of cells to Genz-123346 and to other GCS inhibitors at non-toxic concentrations can enhance the killing of tumor cells by cytotoxic anti-cancer agents. This activity was unrelated to lowering intracellular glycosphingolipid levels. Genz-123346 and a few other GCS inhibitors are substrates for multi-drug resistance efflux pumps such as P-gp (ABCB1, gP-170). In cell lines selected to over-express P-gp or which endogenously express P-gp, chemosensitization by Genz-123346 was primarily due to the effects on P-gp function. RNA interference studies using siRNA or shRNA confirmed that lowering GCS expression in tumor cells did not affect their responsiveness to commonly used cytotoxic drugs.

Phase I/II study of vaccination with electrofused allogeneic dendritic cells/autologous tumor-derived cells in patients with stage IV renal cell carcinoma.

In the present study, we assessed the feasibility, toxicity, immunologic response, and clinical efficacy of vaccination with allogeneic dendritic cell (DC)/tumor fusions in patients with metastatic renal cell carcinoma (RCC). Patients with stage IV RCC with accessible tumor lesions or independent therapeutic indications for nephrectomy were eligible for enrollment. Tumors were processed into single cell suspensions and cryopreserved. DCs were generated from adherent peripheral blood mononuclear cells isolated from normal volunteers and cultured with granulocyte macrophage colony-stimulating factor, interleukin-4, and tumor necrosis factor-alpha. DCs were fused to patient derived RCC with serial electrical pulses. Patients received up to 3 vaccinations at a fixed dose of 4x10(7) to 1x10(8) cells administered at 6-week intervals. Twenty-four patients underwent vaccination. Twenty-one and 20 patients were evaluable for immunologic and clinical response, respectively. DCs demonstrated a characteristic phenotype with prominent expression of HLA class II and costimulatory molecules. A mean fusion efficiency of 20% was observed, determined by the percent of cells coexpressing DC and tumor antigens. No evidence of significant treatment related toxicity or auto-immunity was observed. Vaccination resulted in antitumor immune responses in 10/21 evaluable patients as manifested by an increase in CD4 and/or CD8 T-cell expression of interferon-gamma after ex vivo exposure to tumor lysate. Two patients demonstrated a partial clinical response by Response Evaluation Criteria in Solid Tumors criteria and 8 patients had stabilization of their disease. Vaccination of patients with RCC with allogeneic DC/tumor fusions was feasible, well tolerated, and resulted in immunologic and clinical responses in a subset of patients.

Phase II study of pemetrexed with and without folic acid and vitamin B12 as front-line therapy in malignant pleural mesothelioma.

PURPOSE: This phase II clinical study evaluated the efficacy of pemetrexed for the treatment of malignant pleural mesothelioma (MPM). PATIENTS AND METHODS: Patients with a histologically proven diagnosis of MPM, chemotherapy-naive measurable lesions, and adequate organ function received pemetrexed (500 mg/m2) intravenously over 10 minutes every 3 weeks. After a protocol change, most patients also received folic acid and vitamin B12 supplementation to improve safety. RESULTS: A total of 64 patients were enrolled. Nine (14.1%) of the 64 patients had a partial response. The Kaplan-Meier estimate for median overall survival was 10.7 months. Forty-three patients received vitamin supplementation for all courses of therapy, and 21 patients did not. Seven of the nine responders were vitamin supplemented. The median overall survival was 13.0 months for supplemented patients and 8.0 months for nonsupplemented patients. Vitamin-supplemented patients completed more cycles of therapy than nonsupplemented patients (median, six v two cycles, respectively). Grade 3/4 neutropenia (23.4%) and grade 3/4 leukopenia (18.8%) were the most common laboratory toxicities. Fatigue and febrile neutropenia were the most commonly reported nonlaboratory events (grade 3, 6.3%; grade 4, 0.0% each). The incidence of these toxicities was generally lower in the supplemented patients. CONCLUSION: Single-agent pemetrexed for MPM resulted in a moderate response rate (14.1%) and median overall survival of 10.7 months. Patients supplemented with folic acid and vitamin B12 tolerated treatment better (less toxicity and more cycles of treatment) and had a 5-month greater median overall survival than nonsupplemented patients. These results indicate that patients with MPM could benefit from single-agent pemetrexed treatment combined with vitamin supplementation.

Mga2p processing by hypoxia and unsaturated fatty acids in Saccharomyces cerevisiae: impact on LORE-dependent gene expression.

In Saccharomyces cerevisiae, OLE1 encodes a delta9 fatty acid desaturase, an enzyme that plays a critical role in maintaining the correct ratio of saturated to monounsaturated fatty acids in the cell membrane. Previous studies have demonstrated that (i) OLE1 expression is repressed by unsaturated fatty acids (UFAs) and induced by low oxygen tension, (ii) a component of this regulation is mediated through the same low oxygen response element (LORE) in the OLE1 promoter, and (iii) Mga2p is involved in LORE-dependent hypoxic induction of OLE1. We now report that LORE-CYC1 basal promoter-lacZ fusion reporter assays demonstrate that UFAs repress the reporter expression under hypoxic conditions in a dose-dependent manner via LORE. Electrophoretic mobility shift assays show that UFAs repress the hypoxia-induced complex formation with LORE. Studies with a construct encoding a truncated form of Mga2p support the hypothesis that both hypoxia and UFA signals affect the processing of Mga2p and the UFA repression of OLE1 hypoxic induction is mediated through Mga2p. Data from Western blot assays provide evidence that under normoxic conditions, Mga2p processing produces approximately equimolar levels of the membrane-bound and processed forms and is unaffected by UFAs. Hypoxic induction of OLE1, however, is associated with increased processing of the protein, resulting in an approximately fivefold increase in the soluble active form that is counteracted by exposure of the cells to unsaturated fatty acids. Data from this study suggest that the Mga2p-LORE interaction plays an important role in OLE1 expression under both normoxic and hypoxic conditions.