A phase II study of ixabepilone and trastuzumab for metastatic HER2-positive breast cancer.

BACKGROUND: A multicenter NCI-sponsored phase II study was conducted to analyze the safety and efficacy of the combination of ixabepilone with trastuzumab in patients with metastatic HER2-positive breast cancer. PATIENTS AND METHODS: Two cohorts were enrolled: cohort 1 had received no prior chemotherapy or trastuzumab for metastatic disease and cohort 2 had received 1-2 prior trastuzumab-containing regimens for metastatic disease. Patients in both cohorts received ixabepilone 40 mg/m(2) as a 3-h infusion and trastuzumab on day 1 of a 21-day cycle. Tumor biomarkers that may predict response to trastuzumab were explored. RESULTS: Thirty-nine women entered the study with 15 patients in cohort 1 and 24 patients in cohort 2. Across both cohorts, the overall RR was 44%, with a clinical benefit rate (CR + PR + SD for at least 24 weeks) of 56%. Treatment-related toxic effects included neuropathy (grade ≥2, 56%), leukopenia (grade ≥2, 26%), myalgias (grade ≥2, 21%), neutropenia (grade ≥2, 23%), and anemia (grade ≥2, 18%). CONCLUSIONS: This represents the first study of the combination of ixabepilone with trastuzumab for the treatment of metastatic HER2-positive breast cancer. These results suggest that the combination has encouraging activity as first and subsequent line therapy for metastatic breast cancer.

Identification of a subpopulation of metastatic breast cancer patients with very high HER2 expression levels and possible resistance to trastuzumab.

BACKGROUND: Patients with metastatic breast cancer (MBC) overexpressing HER2 (human epidermal growth factor receptor 2) are currently selected for treatment with trastuzumab, but not all patients respond. PATIENTS AND METHODS: Using a novel assay, HER2 protein expression (H2T) was measured in formalin-fixed, paraffin-embedded primary breast tumors from 98 women treated with trastuzumab-based therapy for MBC. Using subpopulation treatment effect pattern plots, the population was divided into H2T low (H2T < 13.8), H2T high (H2T ≥ 68.5), and H2T intermediate (13.8 ≤ H2T < 68.5) subgroups. Kaplan-Meier (KM) analyses were carried out comparing the groups for time to progression (TTP) and overall survival (OS). Cox multivariate analyses were carried out to identify correlates of clinical outcome. Bootstrapping analyses were carried out to test the robustness of the results. RESULTS: TTP improved with increasing H2T until, at the highest levels of H2T, an abrupt decrease in the TTP was observed. KM analyses demonstrated that patients with H2T low tumors [median TTP 4.2 months, hazard ratio (HR) = 3.7, P < 0.0001] or H2T high tumors (median TTP 4.6 months, HR = 2.7, P = 0.008) had significantly shorter TTP than patients whose tumors were H2T intermediate (median TTP 12 months). OS analyses yielded similar results. CONCLUSIONS: MBC patients with very high levels of H2T may represent a subgroup with de novo resistance to trastuzumab. These results are preliminary and require confirmation in larger controlled clinical cohorts.

Very high quantitative tumor HER2 content and outcome in early breast cancer.

BACKGROUND: It is unknown how a very high tumor total HER2 (human epidermal growth factor receptor-2) content (H2T) influences outcome in early breast cancer treated with adjuvant trastuzumab plus chemotherapy. PATIENTS AND METHODS: H2T was measured using a novel quantitative assay (HERmark(®)) from formalin-fixed tumor tissue of 899 women who participated in the FinHer trial (ISRCTN76560285). In a chromogenic in situ hybridization (CISH) test, 197 (21.9%) patients had HER2-positive cancer and were randomly assigned to receive trastuzumab or control. RESULTS: Cancer H2T levels varied 1808-fold. High H2T levels were correlated with a positive HER2 status by CISH (P < 0.0001). A nonlinear association was present between H2T and the hazard of distant recurrence in a subpopulation treatment effect pattern plot analysis in CISH-positive disease. Patients with very high H2T (defined by ≥22-fold the median of HER2-negative cancers; 13% of CISH-positive cancers) did not benefit from adjuvant trastuzumab [hazard ratio (HR) 1.23; 95% confidence interval (CI) 0.33-4.62; P = 0.75], whereas the rest of the patients with HER2-positive disease by CISH (87%) did benefit (HR 0.52; 95% CI 0.28-1.00; P = 0.050). CONCLUSION: Patients with HER2-positive breast cancer with very high tumor HER2 content may benefit less from adjuvant trastuzumab compared with those whose cancer has more moderate HER2 content.

Phage display selection of a peptide DNase II inhibitor that enhances gene delivery.

BACKGROUND: Nuclease activity is thought to be a significant barrier to effective gene delivery employing synthetic vectors. In particular, the lysosomal DNase, DNase II, has significant access to plasmid DNA, when the protective condensing agent has been shed. Here, we present the identification of a peptide DNase II inhibitor, enabling enhanced levels of gene delivery. METHODS: A DNase II inhibitor was identified by phage display from a cyclic, random 12-amino acid library. Activity was assayed by inhibition of DNase II degradation of DNA. Transfection enhancement levels were measured over a range of DNA doses with CV-1 and MDBK cell types using PEI and cationic lipoplexes as vectors. RESULTS: We postulated that a DNase II inhibitor would enhance transfection by enabling a larger fraction of plasmid DNA to traffic through the cell and enter the nucleus. Peptides based on the selected sequence (SLRLLQWFLWAC) [ID2] were shown to inhibit DNase II with an observed KI,app of 0.2-2 microM. Lipoplex-mediated transfection in vitro was found to be enhanced by ID2-3 across the entire range of plasmid DNA doses examined (0.10-3.0 microg/mL). Transfection with PEI/DNA complexes was found to be specifically enhanced in the presence of ID2 peptides, with a saturable DNA-dose curve as would be expected for a competitive inhibitor. Transfection enhancements as high as 270-fold were found in the presence of ID2-3. CONCLUSIONS: A novel peptide DNase II inhibitor has been used to increase transfection. The level of enhancement was found to be significant in multiple cell types with multiple synthetic vectors.

Tresyl-mediated synthesis: kinetics of competing coupling and hydrolysis reactions as a function of pH, temperature, and steric factors.

Kinetic parameters have been measured for coupled nucleophilic and solvolytic reactions of 2,2,2-trifluoroethanesulfonyl (tresyl)-modified poly(ethylene glycol) based on a system of coupled differential equations implied by recently proposed elementary reaction mechanisms. Fitted kinetic parameters were found to be strong functions of pH, temperature, and steric factors. To maximize the total yield of coupled amine as well as the fraction of secondary amine linkages, our model predicts that it is desirable to run tresyl coupling reactions at low temperatures at pH approximately 8.0, depending on the amine pKa for primary, unhindered amines. For branched primary amines, our data favor room temperature at a slightly higher pH.

Radiological physics characteristics of the extracted heavy ion beams of the bevatron.

Studies of the depth-ionization properties and the biological effects of heavy ion beams produced at the bevatron have extended work previously done with less energetic beams from other sources. Results indicate that heavy ion beams are suitable for tumor therapy, studies relating to space biology, and fundamental radiobiology.