Binary Targeting of siRNA to Hematologic Cancer Cells In Vivo using Layer-by-Layer Nanoparticles.

Using siRNA therapeutics to treat hematologic malignancies has been unsuccessful because blood cancer cells exhibit remarkable resistance to standard transfection methods. Herein we report the successful delivery of siRNA therapeutics with a dual-targeted, layer-by-layer nanoparticle (LbL-NP). The LbL-NP protects siRNA from nucleases in the bloodstream by embedding it within polyelectrolyte layers that coat a polymeric core. The outermost layer consists of hyaluronic acid (a CD44-ligand) covalently conjugated to CD20 antibodies. The CD20/CD44 dual-targeting outer layer provides precise binding to blood cancer cells, followed by receptor-mediated endocytosis of the LbL-NP. We use this siRNA delivery platform to silence B-cell lymphoma 2 (BCL-2), a pro-survival protein, in vitro and in vivo. The dual-targeting approach significantly enhanced internalization of BCL-2 siRNA in lymphoma and leukemia cells, which led to significant downregulation of BCL-2 expression. Systemic administration of the dual-targeted, siRNA-loaded nanoparticle induced apoptosis and hampered proliferation of blood cancer cells both in cell culture and in orthotopic non-Hodgkin's lymphoma animal models. These results provide the basis for approaches to targeting blood-borne cancers and other diseases, and suggest that LbL nanoassemblies are a promising approach for delivering therapeutic siRNA to hematopoetic cell types that are known to evade transfection by other means.

Case-control study of the association between select HLA genes and anti-erythropoietin antibody-positive pure red-cell aplasia.

AIMS: Antibody (Ab)-positive pure red-cell aplasia (PRCA) is a very rare but serious adverse event associated with recombinant human erythropoietin treatment (4.1 reports per 100,000 patient-years) in which patients produce antibodies to recombinant and endogenous erythropoietin, halting red blood cell production. In a previous case series, four Thai subjects with chronic kidney disease and Ab-positive PRCA were reported to have the HLA-DRB1*9 allele. To confirm a possible association of HLA-DRB1*9 and Ab-positive PRCA, we performed a pharmacogenomic analysis using subjects from an earlier case-control study of risk factors associated with Ab-positive PRCA, which had been performed using subjects from Europe or Canada. The primary goal of the analysis was to test the association between HLA-DRB1*9 and Ab-positive PRCA. A secondary goal was to perform an exploratory analysis in order to identify additional HLA alleles potentially associated with Ab-positive PRCA. PATIENTS & METHODS: Subjects were taken from a case-control study of Ab-positive PRCA in chronic kidney disease patients treated in Europe or Canada. Ab-positive PRCA cases (n=24) were matched to controls (n=81) by timing of treatment exposure and, when possible, by location. RESULTS: The allele frequency of HLA-DRB1*9 was 12.5% in cases vs 1.2% in controls (p=0.002). The frequency of the HLA-DRB1*9/other genotype was 25.0% in cases vs 2.5% in controls (p=0.004; OR: 10.8 [95% CI: 2.2-53.7]). Within the exploratory analysis, six additional HLA alleles (HLA-A*25, HLA-B*53, HLA-C*12, HLA-DQB1*3, HLA-DQB1*6 and HLA-DRB1*4) were also found to be associated with Ab-positive PRCA. CONCLUSION: This study confirmed that HLA-DRB1*9 occurs at a significantly higher frequency in Ab-positive PRCA cases than in controls; however, within this sample set, carrying the *9 allele was neither necessary nor sufficient to cause Ab-positive PRCA.

A phase II trial of R115777, an oral farnesyl transferase inhibitor, in patients with advanced urothelial tract transitional cell carcinoma.

BACKGROUND: R115777 is a potent farnesyl transferase inhibitor and has significant antitumor effects in vitro and in vivo. METHODS: The objective of the current study was to determine the objective response proportion in patients with metastatic transitional cell carcinoma (TCC) of the urothelial tract who received treatment with R115777 at a dose of 300 mg orally given twice daily for 21 days followed by 7 days of rest for every 4-week cycle. Thirty-four patients with TCC were enrolled in this Phase II study. Patients were allowed to have received a maximum of one prior systemic chemotherapy regimen, not including chemoradiation or neoadjuvant chemotherapy. All patients were required to have an Eastern Cooperative Oncology Group performance status of 0-2 and adequate bone marrow, hepatic, and kidney function. RESULTS: Twice daily administration of oral R115777 was tolerated well. R115777 was absorbed rapidly after oral administration. Grade 3-4 neutropenia (according to the National Cancer Institute Common Toxicity Criteria [version 2.0]) was observed in 5 patients (15%). Grade 3-4 nonhematologic toxicity was rare, consisting of rash and diarrhea in 1 patient each. Two patients (6%) without prior chemotherapy demonstrated partial responses. Thirteen patients (38%) achieved disease stabilization according to World Health Organization criteria that lasted a median of 4 months. No complete responses were observed. CONCLUSIONS: The objective response rate of R115777 was not sufficient to warrant future investigation in TCC as a single agent. Preliminary evidence of the activity of R115777 in 2 chemotherapy-naive patients may warrant further investigation in combination with first-line chemotherapy.

Phase I and pharmacokinetic study of the farnesyltransferase inhibitor R115777 in combination with irinotecan in patients with advanced cancer.

PURPOSE: R115777 is a selective, nonpeptidomimetic inhibitor of farnesyltransferase (FTase), an enzyme responsible for the post-translational modification of several proteins, including Ras. Given the high frequency of K-Ras mutations in malignancies commonly treated with irinotecan, the broad preclinical antiproliferative activity of R115777 and its largely non-overlapping toxicity profile with irinotecan, this phase I study of the combination of R115777 and irinotecan in patients with advanced cancer was undertaken. PATIENTS AND METHODS: Enrolled onto the study were 14 patients (eight male, six female; median age 63 years, range 48-72 years). Five patients had an ECOG performance status (PS) of 0, eight patients PS 1, and one patient PS 2. The patients were treated with R115777 orally twice daily for 28 days and irinotecan 100 mg/m(2) as an intravenous infusion on days 1, 8, 15, and 22 of each 42-day cycle. Seven patients received R115777 100 mg twice daily and seven received R115777 200 mg twice daily. RESULTS: Dose-limiting toxicity (DLT) was experienced by one of seven patients treated with R115777 100 mg (grade 3 fatigue), and two of seven patients treated with R115777 200 mg (grade 3 diarrhea, grade 4 neutropenia lasting >5 days). The maximum tolerated dose (MTD) was R115777 100 mg twice daily and irinotecan 100 mg/m(2) weekly. Non-DLTs were primarily rash, fatigue, diarrhea, and neutropenia. R115777 demonstrated linear pharmacokinetics without interaction with irinotecan and achieved serum levels required for antitumor activity in vitro. CONCLUSIONS: Serum levels of R115777 exceeded those necessary for FTase inhibition in vitro without evidence of interaction with irinotecan. However, the MTD of R115777 in this study was lower than that obtained with an alternate schedule. Thus, further development of this schedule is not recommended.

A Phase I trial of the farnesyl protein transferase inhibitor R115777 in combination with gemcitabine and cisplatin in patients with advanced cancer.

PURPOSE: This Phase I study was undertaken to define the toxicity, pharmacodynamics, and maximum tolerated dose of the combination of R115777, a farnesyl transferase inhibitor, with gemcitabine and cisplatin in patients with advanced solid tumors. PATIENTS AND METHODS: Thirty patients with solid tumors received a median of 2.5 cycles (range 1-30+) through five dose levels. R115777 was administered p.o. twice daily for 14 days. Gemcitabine was infused 15 min after the ingestion of R115777 on days 1 and 8. Cisplatin was administered starting 30 min after completion of the gemcitabine infusion on day 1. Cycles were repeated every 21 days. Toxicities were graded by the National Cancer Institute Common Toxicity Criteria and recorded as maximum grade per patient for each treatment cycle. At the maximum tolerated dose, accumulation of prelamin A in buccal mucosa cells of patients was evaluated as a marker of farnesyl transferase inhibition by R115777. RESULTS: Neutropenia and thrombocytopenia were the most common toxicities. Dose-limiting toxicity in cycle 1 was myelosuppression with thrombocytopenia alone (4 patients), neutropenia alone (1 patient), or a combination of both (3 patients). Common nonhematologic toxicities were anorexia, rash, nausea, vomiting, and fatigue, none of which was dose limiting in the first cycle. At the maximum tolerated dose, defined as R115777 300 mg twice daily p.o., 1000 mg/m(2) gemcitabine, and 75 mg/m(2) cisplatin, inhibition of prelamin A farnesylation in buccal mucosa cells of patients was demonstrated, confirming that R115777 inhibits protein farnesylation in vivo. Nine objective responses (one complete response and eight partial responses) were documented in 27 evaluable patients. CONCLUSION: The combination of R115777 with gemcitabine and cisplatin was well tolerated and showed evidence of antitumor activity. The maximum tolerated dose of R115777 successfully inhibits farnesyltransferase in patients in vivo. This combination warrants further evaluation in a number of tumor types.