Distinct uptake and elimination profiles for trastuzumab, human IgG and biocytin-TMR in experimental HER2+ brain metastases of breast cancer.

BACKGROUND: The aim of this study is an improved understanding of drug distribution in brain metastases. Rather than single point snapshots, we analyzed the time course and route of drug/probe elimination (clearance), focusing on the Intramural Periarterial Drainage (IPAD) pathway. METHODS: Mice with JIMT1-BR HER2+ experimental brain metastases were injected with biocytin-TMR and either trastuzumab or human IgG. Drugs/probes circulated for 5 min-48h, followed by perfusion. Brain sections were stained for human IgG, vascular basement membrane proteins laminin or collagen IV, and periarterial α-SMA. A machine learning algorithm was developed to identify metastases, metastatic microenvironment, and uninvolved brain in confocally scanned brain sections. Drug/probe intensity over time and total imaged drug exposure (iAUC) were calculated for 27,249 lesions and co-immunofluorescence with IPAD- vascular matrix analyzed in 11,668 metastases. RESULTS: In metastases, peak trastuzumab levels were 5-fold higher than human IgG but 4-fold less than biocytin-TMR. The elimination phase constituted 85-93% of total iAUC for all drugs/probes tested. For trastuzumab, total iAUC during uptake was similar to the small molecule drug probe biocytin-TMR, but slower trastuzumab elimination resulted in a 1.7-fold higher total iAUC. During elimination trastuzumab and IgG were preferentially enriched in the α-SMA+ periarterial vascular matrix, consistent with the IPAD clearance route; biocytin-TMR showed heterogeneous elimination pathways. CONCLUSIONS: Drug/probe elimination is an important component of drug development for brain metastases. We identified a prolonged elimination pathway for systemically administered antibodies through the periarterial vascular matrix that may contribute to the sustained presence and efficacy of large antibody therapeutics.

The Combination of Trametinib and Ganitumab is Effective in RAS-Mutated PAX-Fusion Negative Rhabdomyosarcoma Models.

PURPOSE: PAX-fusion negative rhabdomyosarcoma (FN RMS) is driven by alterations in the RAS/MAP kinase pathway and is partially responsive to MEK inhibition. Overexpression of IGF1R and its ligands is also observed in FN RMS. Preclinical and clinical studies have suggested that IGF1R is itself an important target in FN RMS. Our previous studies revealed preclinical efficacy of the MEK1/2 inhibitor, trametinib, and an IGF1R inhibitor, BMS-754807, but this combination was not pursued clinically due to intolerability in preclinical murine models. Here, we sought to identify a combination of an MEK1/2 inhibitor and IGF1R inhibitor, which would be tolerated in murine models and effective in both cell line and patient-derived xenograft models of RAS-mutant FN RMS. EXPERIMENTAL DESIGN: Using proliferation and apoptosis assays, we studied the factorial effects of trametinib and ganitumab (AMG 479), a mAb with specificity for human and murine IGF1R, in a panel of RAS-mutant FN RMS cell lines. The molecular mechanism of the observed synergy was determined using conventional and capillary immunoassays. The efficacy and tolerability of trametinib/ganitumab was assessed using a panel of RAS-mutated cell-line and patient-derived RMS xenograft models. RESULTS: Treatment with trametinib and ganitumab resulted in synergistic cellular growth inhibition in all cell lines tested and inhibition of tumor growth in four of six models of RAS-mutant RMS. The combination had little effect on body weight and did not produce thrombocytopenia, neutropenia, or hyperinsulinemia in tumor-bearing SCID beige mice. Mechanistically, ganitumab treatment prevented the phosphorylation of AKT induced by MEK inhibition alone. Therapeutic response to the combination was observed in models without a mutation in the PI3K/PTEN axis. CONCLUSIONS: We demonstrate that combined trametinib and ganitumab is effective in a genomically diverse panel of RAS-mutated FN RMS preclinical models. Our data also show that the trametinib/ganitumab combination likely has a favorable tolerability profile. These data support testing this combination in a phase I/II clinical trial for pediatric patients with relapsed or refractory RAS-mutated FN RMS.

Biological Effects of Modifications of the Englerin A Glycolate.

Modifications at the glycolate moiety of englerin A were made to explore variations at the most sensitive site on the molecule for activity in the NCI 60 screen, wherein englerin A is highly potent and selective for renal cancer cells. Replacement of the glycolate by other functionalities as well as esterification of the glycolate hydroxyl yielded compounds which displayed excellent selectivity and potency compared with the natural product. TRPC4/5 ion channel experiments with five compounds showed delayed or reduced agonism with TRPC5, at much higher concentrations than englerin A. With TRPC4, these compounds all had no effect at 10 µM. The same compounds were not detectable in mouse serum after a single oral dose of 12.5 mg/kg. At 100 mg/kg p.o., no toxicity was observed, and blood levels were barely detectable. Intravenous administration led to toxicity but at substantially lower doses than for englerin A.

A phase I trial of lenalidomide and radiotherapy in children with diffuse intrinsic pontine gliomas or high-grade gliomas.

PURPOSE: This study was performed to determine the maximum tolerated dose (MTD) or recommended phase 2 dose (RP2D) of the immunomodulatory agent, lenalidomide, when administered daily during 6 weeks of radiation therapy to children with newly diagnosed diffuse intrinsic pontine glioma (DIPG) or high-grade glioma (HGG) PATIENTS & METHODS: Children and young adults < 22 years of age with newly diagnosed disease and no prior chemotherapy or radiation therapy were eligible. Children with HGG were required to have an inoperable or incompletely resected tumor. Eligible patients received standard radiation therapy to a prescription dose of 54-59.4 Gy, with concurrent administration of lenalidomide daily during radiation therapy in a standard 3 + 3 Phase I dose escalation design. Following completion of radiation therapy, patients had a 2-week break followed by maintenance lenalidomide at 116 mg/m2/day × 21 days of a 28-day cycle. RESULTS: Twenty-nine patients (age range 4-19 years) were enrolled; 24 were evaluable for dose finding (DIPG, n = 13; HGG, n = 11). The MTD was not reached at doses of lenalidomide up to 116 mg/m2/day. Exceptional responses were noted in DIPG and malignant glioma (gliomatosis cerebri) notably at higher dose levels and at higher steady state plasma concentrations. The primary toxicity was myelosuppression. CONCLUSION: The RP2D of lenalidomide administered daily during radiation therapy is 116 mg/m2/day. Children with malignant gliomas tolerate much higher doses of lenalidomide during radiation therapy compared to adults. This finding is critical as activity was observed primarily at higher dose levels suggesting a dose response.

Synthesis of a stable and orally bioavailable englerin analogue.

Synthesis of analogues of englerin A with a reduced propensity for hydrolysis of the glycolate moiety led to a compound which possessed the renal cancer cell selectivity of the parent and was orally bioavailable in mice.

Pharmacodynamic markers and clinical results from the phase 2 study of the SMAC mimetic birinapant in women with relapsed platinum-resistant or -refractory epithelial ovarian cancer.

BACKGROUND: Inhibitors of apoptosis proteins (IAPs) are key regulators of apoptosis and are frequently dysregulated in ovarian cancer. It was hypothesized that blocking IAPs with birinapant would increase tumor cell death and result in objective responses for women with platinum-refractory and -resistant ovarian cancer. METHODS: In this phase 2, Cancer Therapy Evaluation Program-sponsored study, patients received birinapant at 47 mg/m(2) on days 1, 8, and 15 of 28-day cycles. Pharmacokinetics were obtained during cycle 1. Plasma, peripheral blood mononuclear cells (PBMCs), and percutaneous tumor biopsy samples were collected before cycle 1 and after 6 weeks. The primary endpoint was an objective response or progression-free survival lasting greater than 6 months in a mini-max design. RESULTS: Eleven patients received birinapant; after this, accrual was terminated for lack of a clinical benefit. Birinapant was well tolerated, with predominantly grade 2 adverse events and 1 case of grade 3 lymphopenia. Pretreatment biopsy samples and PBMCs were collected; paired posttreatment biopsy samples and PBMCs were collected from 7 and 10 patients, respectively. There was consistent downregulation of cellular inhibitor of apoptosis protein 1 in tumors (P = .016) and PBMCs (P < .01). Procaspase 3 also decreased in tumors (P = .031) and PBMCs (P < .01); cleaved caspase 3 colocalized with H2A histone family member X (γ-H2AX) in tumors after birinapant exposure. Peripheral T and B cells decreased significantly after treatment, but natural killer cells did not (P = .04, P = .05, and P = .43, respectively). CONCLUSIONS: Birinapant shows consistent target suppression in vivo without single-agent antitumor activity in this small population. Single-agent pharmacodynamics are necessary to understand the drug's mechanism of action and set the stage for rational combination therapy. Preclinical studies are ongoing to identify optimal synergistic combinations for future clinical trials.

Finasteride metabolism and pharmacogenetics: new approaches to personalized prevention of prostate cancer.

Incidences of prostate cancer in most countries are increasing owing to better detection methods; however, prevention with the use of finasteride, a very effective steroid 5α-reductase type II inhibitor, has been met with mixed success. A wide interindividual variation in response exists and is thought to be due to heritable factors. This article summarizes the literature that attempts to elucidate the molecular mechanisms of finasteride in terms of its metabolism, excretion and interaction with endogenous steroid molecules. We describe previously reported genetic variations of steroid-metabolizing genes and their potential association with finasteride efficacy. Based on the literature, we outline directions of research that may contribute to understanding the interindividual variation in finasteride prevention and to the future development of personalized medicine.

A Polymorphic Variant of AFAP-110 Enhances cSrc Activity.

Enhanced expression and activity of cSrc are associated with ovarian cancer progression. Generally, cSrc does not contain activating mutations; rather, its activity is increased in response to signals that affect a conformational change that releases its autoinhibition. In this report, we analyzed ovarian cancer tissues for the expression of a cSrc-activating protein, AFAP-110. AFAP-110 activates cSrc through a direct interaction that releases it from its autoinhibited conformation. Immunohistochemical analysis revealed a concomitant increase of AFAP-110 and cSrc in ovarian cancer tissues. An analysis of the AFAP-110 coding sequence revealed the presence of a nonsynonymous, single-nucleotide polymorphism that resulted in a change of Ser403 to Cys403. In cells that express enhanced levels of cSrc, AFAP-110(403C) directed the activation of cSrc and the formation of podosomes independently of input signals, in contrast to wild-type AFAP-110. We therefore propose that, under conditions of cSrc overexpression, the polymorphic variant of AFAP-110 promotes cSrc activation. Further, these data indicate amechanismby which an inherited genetic variation could influence ovarian cancer progression and could be used to predict the response to targeted therapy.

Medroxyprogesterone acetate elevation of Nm23-H1 metastasis suppressor expression in hormone receptor-negative breast cancer.

BACKGROUND: Reestablishment of metastasis suppressor gene expression may constitute a therapeutic strategy for high-risk breast cancer patients. We previously showed that medroxyprogesterone acetate (MPA), a progestin that has been tested as treatment for advanced breast cancer, elevates expression of the Nm23-H1 metastasis suppressor gene in hormone receptor-negative metastatic human breast carcinoma cell lines in vitro via a glucocorticoid receptor-based mechanism. Here, we tested whether MPA treatment inhibits metastatic colonization of a hormone receptor-negative breast cancer cell line in vivo. METHODS: We tested the soft-agar colony-forming efficiency of untransfected MDA-MB-231T human breast carcinoma cells and MDA-MB-231T cells transfected with antisense Nm23-H1 in the presence and absence of MPA. Pharmacokinetic studies were used to establish dose and injection schedules that led to MPA serum levels in mice similar to those achievable in humans. For in vivo studies, nude mice were injected intravenously with MDA-MB-231T cells. After 4 weeks, mice were randomized to control or MPA arms. Endpoints included incidence, number, and size of gross pulmonary metastases; Nm23-H1 protein expression in gross metastases; and side effects. All statistical tests were two-sided. RESULTS: MPA reduced colony formation of MDA-MB-231T cells by 40%-50% but had no effect on colony formation of Nm23-H1 antisense transfectants. Metastases developed in 100% (95% confidence interval [CI] = 78% to 100% and 77% to 100%, respectively) of control mice injected with MDA-MB-231T cells. In two independent experiments, only 73% (95% CI = 45% to 92%) and 64% (95% CI = 35% to 87%) of mice injected with 2 mg of MPA developed metastases. Mice injected with 2 mg of MPA showed reductions in the mean numbers, per mouse, of all metastases and of large (>3 mm) metastases (P = .04 and .013, respectively). Nm23-H1 was expressed at high levels in 43% of pulmonary metastases in MPA-treated mice but only 13% of metastases in untreated mice. Mice receiving at least 1-mg doses of MPA gained more weight than control-treated mice but exhibited no bone density alterations or abnormal mammary fat pad histology. CONCLUSION: Our preclinical results show that MPA appears to elevate Nm23-H1 metastasis suppressor gene expression, thereby reducing metastatic colonization. The data suggest a new use for an old agent in a molecularly defined subset of breast cancer patients.

Micellar paclitaxel improves severe psoriasis in a prospective phase II pilot study.

BACKGROUND: Taxanes (eg, paclitaxel) are chemotherapeutic agents that have antiproliferative, antiangiogenic, and antiinflammatory properties. OBJECTIVE: We sought to explore the safety and efficacy of paclitaxel in individuals with severe psoriasis. METHODS: An open-label, prospective, phase II pilot study was conducted at the National Institutes of Health Clinical Center, a federal government medical research facility, in Bethesda, Maryland. Twelve patients with severe psoriasis, as defined by a baseline Psoriasis Area and Severity Index (PASI) score of >or= 20), were studied. Initially, patients received 6 intravenous infusions of micellar paclitaxel, 75 mg/m(2), at 4-week intervals (stage I). Later patients received 9 intravenous infusions of micellar paclitaxel at 2-week intervals (37.5 mg/m(2) for 3 doses followed by 50 mg/m(2) for six additional doses) (stage II). The primary end point was the percent change in the PASI from week 0 to week 24 in stage I and from week 0 to week 20 in stage II. RESULTS: In stage I, all 5 patients improved (mean = 59.7% decrease in PASI, median = 59.6%, range: 40.3%-79.2%). Four of the 7 patients completed stage II and all of these patients improved (mean = 45.9% decrease in PASI, median = 45.0%, range: 14.6%-79.1%). Micellar paclitaxel was well tolerated by most patients. CONCLUSIONS: Micellar paclitaxel demonstrates therapeutic activity in patients with severe psoriasis.