A phase I study of AT-101 with cisplatin and etoposide in patients with advanced solid tumors with an expanded cohort in extensive-stage small cell lung cancer.

BACKGROUND: A phase I, dose-escalation study of AT-101 with cisplatin and etoposide was conducted to determine the maximum tolerated dose (MTD)/recommended phase 2 dose (RP2D), safety and pharmacokinetics in patients with advanced solid tumors, with an expanded cohort in patients with extensive-stage small cell lung cancer (ES-SCLC) to assess preliminary activity. METHODS: In the dose escalation portion, increasing doses of AT-101 were administered orally BID on days 1-3 along with cisplatin on day 1 and etoposide on days 1-3 of a 21 day cycle. At the RP2D, an additional 7 patients with untreated ES-SCLC were enrolled. RESULTS: Twenty patients were enrolled in the dose-escalation cohort, and 7 patients with ES-SCLC were enrolled in the expanded cohort. The MTD/RP2D was established at AT-101 40 mg BID days 1-3 with cisplatin 60 mg/m2 and etoposide 120 mg/m2 on day 1 of a 21 day cycle with pegfilgrastim support. Two DLTs of neutropenic fever were seen at dose level 1. After the addition of pegfilgrastim, no additional DLTs were observed. Grade 3/4 treatment-related toxicities included: diarrhea, increased AST, neutropenia, hypophosphatemia, hyponatremia, myocardial infarction and pulmonary embolism. No apparent PK interactions were observed between the agents. Preliminary activity was observed with PRs in patients with ES-SCLC, high-grade neuroendocrine tumor, esophageal cancer and NSCLC. CONCLUSIONS: AT-101 with cisplatin and etoposide is well tolerated with growth factor support. Anti-tumor activity was observed in a variety of cancers including ES-SCLC, supporting further investigation with BH-3 mimetics in combination with standard chemotherapy for ES-SCLC.

A pilot phase II study of valproic acid for treatment of low-grade neuroendocrine carcinoma.

INTRODUCTION: Notch1 has been shown to be a tumor suppressor in neuroendocrine tumors (NETs). Previous in vitro studies in NET cell lines have also suggested that valproic acid (VPA), a histone deacetylase inhibitor, can induce Notch1 and that Notch1 activation correlates with a decrease in tumor markers for NETs. Thus, this study aimed to evaluate the role of VPA in treating NETs and to determine whether VPA induced the Notch signaling pathway signaling in vivo. PATIENTS AND METHODS: Eight patients with low-grade NETs (carcinoid and pancreatic) were treated with 500 mg of oral VPA twice a day with dosing adjusted to maintain a goal VPA level between 50 and 100 µg/mL. All patients were followed for 12 months or until disease progression. RESULTS: Notch1 signaling was absent in all tumors prior to treatment and was upregulated with VPA. One patient had an unconfirmed partial response and was noted to have a 40-fold increase in Notch1 mRNA levels. Four patients had stable disease as best response. Tumor markers improved in 5 out of 7 patients. Overall, treatment with VPA was well tolerated. CONCLUSION: . VPA activates Notch1 signaling in vivo and may have a role in treating low-grade NETs.

Abnormal fiber end migration in Royal College of Surgeons rats during posterior subcapsular cataract formation.

PURPOSE: Prior structural studies of posterior subcapsular cataract (PSC) development in Royal College of Surgeons (RCS) rats suggest that migration of basal fiber ends was disrupted, ultimately resulting in a PSC. Therefore the goal of this study was to assess the overall migration patterns as well as changes to the structure and cytoskeleton of basal fiber ends during PSC development. METHODS: Lenses from 48 RCS dystrophic rats (RCS/Lav) and 24 genetically matched control animals (RCS-rdy(+)/Lav) from 2 to 8 weeks old were examined. Equatorial diameters were measured and suture patterns were photographed immediately following enucleation/dissection. Right eye lenses were fixed and processed to visualize the actin cytoskeleton via laser scanning confocal microscopy (LSCM), left eye lenses were decapsulated, fixed and processed for scanning electron microscopy (SEM). Scaled 3D-computer assisted drawings (CADs) and animations were constructed from the data to depict the changes in suture patterns and fiber end architecture. RESULTS: At 2 weeks, dystrophic lenses displayed an inverted Y suture on the posterior, and by 3 weeks most lenses had at least one sub-branch. Additional sub-branches were observed with time, opacities being visible as early as 4 weeks and progressing into PSC plaques by 6 weeks. Control lenses displayed inverted Y sutures at all ages and were transparent. SEM of dystrophic lenses revealed fiber ends with normal size, shape, arrangement, and filopodia at 2 weeks; scattered areas of dome-shaped fiber ends and small filopodia were present at 3 weeks. At 4 weeks the irregularly arranged domed fiber ends had extremely long filopodia with 'boutons' at their tips. By 6 weeks all fiber ends within plaques displayed rounded or domed basal membranes and lacked filopodial extensions. Control lenses at all time points had comparable ultrastructure to the 2 week old dystrophic lenses. F-actin arrangement within the basal membrane complex (BMC) of control lenses showed the expected peripheral pattern of labeling at all ages. Dystrophic RCS lenses at 2 weeks were comparable to controls, however by 3-4 weeks they displayed scattered foci of F-actin within the BMC. At all time points thereafter, F-actin was rearranged into a 'rosette' pattern of prominent foci at cell vertices. CONCLUSIONS: The data are consistent with the hypothesis that migration of basal fiber ends is altered in a two stage process wherein initially, migration patterns undergo a rapid shift resulting in abnormal suture sub-branch formation. Subsequent cytological alterations are consistent with an eventual cessation of migration, precluding proper targeting of basal ends to their sutural destinations and leading to cataract plaque formation.

Distribution of basal membrane complex components in elongating lens fibers.

PURPOSE: To localize specific components of the Basal Membrane Complex (BMC) of elongating lens fibers at defined points in their migration to the posterior sutures. METHODS: Normal, juvenile (4-6 week old) Sprague-Dawley rat lenses (n=46) were utilized. Lenses were either decapsulated to obtain whole mounts of lens capsules or sectioned with a vibrating knife microtome. Sections (100 microm thick) were cut parallel to the equatorial plane, beginning at the posterior pole. On both sections and whole mounts, F-actin was localized using phalloidin-FITC while myosin, cadherins, and beta1 integrin were localized using immunofluorescent labeling. Specimens were visualized on a laser scanning confocal microscope. RESULTS: F-actin labeling in the equatorial and peri-sutural regions was predominately localized to the periphery of basal fiber ends (consistent with our prior results). At sutures, labeling for F-actin in the BMC was rearranged into numerous small profiles. Furthermore, labeling intensity for F-actin was increased at sutures. Myosin was present in the BMC in all locations examined as a diffuse plaque at fiber ends. Similarly, beta1 integrin was also distributed throughout the BMC within the actin-rich borders in all regions except adjacent to and at the suture branches. In that location immunofluorescence for beta1 integrin appeared to be reduced. In the equatorial, lateral-posterior, and peri-sutural regions, cadherin showed strong localization around the periphery of basal fiber ends. However, cadherin labeling was markedly reduced in the BMC as fibers detached from the capsule and abutted to form sutures (i.e. in the sutural region). Cadherin was concentrated along the short faces of elongating fiber mid-segments. CONCLUSIONS: It appears that F-actin, cadherin and beta1 integrin components of the BMC undergo controlled rearrangements in the final stages of migration and detachment from the capsule.