Tsivia Hochman

Essential role for eIF4GI overexpression in the pathogenesis of inflammatory breast cancer

Inflammatory breast cancer (IBC) is the most lethal form of primary breast cancer. IBC lethality derives from generation of tumour emboli, which are non-adherent cell clusters that rapidly spread by a form of continuous invasion known as passive metastasis. In most cancers, expression of E-cadherin, an epithelial marker, is indicative of low metastatic potential. In IBC, E-cadherin is overexpressed and supports formation of tumour emboli by promoting tumour cell interactions rather than adherence to stroma. E-cadherin, a surface component of adherens junctions, is anchored by interaction with p120 catenin (p120). We show that the unique pathogenic properties of IBC result in part from overexpression of the translation initiation factor eIF4GI in most IBCs. eIF4GI reprograms the protein synthetic machinery for increased translation of mRNAs with internal ribosome entry sites (IRESs) that promote IBC tumour cell survival and formation of tumour emboli. Overexpression of eIF4GI promotes formation of IBC tumour emboli by enhancing translation of IRES-containing p120 mRNAs. These findings provide a new understanding of translational control in the development of advanced breast cancer.

Topical TLR7 Agonist Imiquimod Can Induce Immune-Mediated Rejection of Skin Metastases in Patients with Breast Cancer

Purpose: Skin metastases of breast cancer remain a therapeutic challenge. Toll-like receptor 7 agonist imiquimod is an immune response modifier and can induce immune-mediated rejection of primary skin malignancies when topically applied. Here we tested the hypothesis that topical imiquimod stimulates local antitumor immunity and induces the regression of breast cancer skin metastases. Experimental Design: A prospective clinical trial was designed to evaluate the local tumor response rate of breast cancer skin metastases treated with topical imiquimod, applied 5 d/wk for 8 weeks. Safety and immunologic correlates were secondary objectives. Results: Ten patients were enrolled and completed the study. Imiquimod treatment was well tolerated, with only grade 1 to 2 transient local and systemic side effects consistent with imiquimods immunomodulatory effects. Two patients achieved a partial response [20%; 95% confidence interval (CI), 3%–56%]. Responders showed histologic tumor regression with evidence of an immune-mediated response, showed by changes in the tumor lymphocytic infiltrate and locally produced cytokines. Conclusion: Topical imiquimod is a beneficial treatment modality for breast cancer metastatic to skin/chest wall and is well tolerated. Importantly, imiquimod can promote a proimmunogenic tumor microenvironment in breast cancer. Preclinical data generated by our group suggest superior results with a combination of imiquimod and ionizing radiation and we are currently testing in patients whether the combination can further improve antitumor immune and clinical responses. Clin Cancer Res; 18(24); 6748–57. ©2012 AACR.

Phase II study of sorafenib in children with recurrent or progressive low-grade astrocytomas

BACKGROUND Activation of the RAS-RAF-MEK-ERK signaling pathway is thought to be the key driver of pediatric low-grade astrocytoma (PLGA) growth. Sorafenib is a multikinase inhibitor targeting BRAF, VEGFR, PDGFR, and c-kit. This multicenter phase II study was conducted to determine the response rate to sorafenib in patients with recurrent or progressive PLGA. METHODS Key eligibility criteria included age ≥ 2 years, progressive PLGA evaluable on MRI, and at least one prior chemotherapy treatment. Sorafenib was administered twice daily at 200 mg/m(2)/dose (maximum of 400 mg/dose) in continuous 28-day cycles. MRI, including 3-dimensional volumetric tumor analysis, was performed every 12 weeks. BRAF molecular testing was performed on tumor tissue when available. RESULTS Eleven patients, including 3 with neurofibromatosis type 1 (NF1), were evaluable for response; 5 tested positive for BRAF duplication. Nine patients (82%) came off trial due to radiological tumor progression after 2 or 3 cycles, including 3 patients with confirmed BRAF duplication. Median time to progression was 2.8 months (95% CI, 2.1-31.0 months). Enrollment was terminated early due to this rapid and unexpectedly high progression rate. Tumor tissue obtained from 4 patients after termination of the study showed viable pilocytic or pilomyxoid astrocytoma. CONCLUSIONS Sorafenib produced unexpected and unprecedented acceleration of tumor growth in children with PLGA, irrespective of NF1 or tumor BRAF status. In vitro studies with sorafenib indicate that this effect is likely related to paradoxical ERK activation. Close monitoring for early tumor progression should be included in trials of novel agents that modulate signal transduction.

A phase I study of panobinostat (LBH589) in patients with primary myelofibrosis (PMF) and post‐polycythaemia vera/essential thrombocythaemia myelofibrosis (post‐PV/ET MF)

Panobinostat (LBH589), a novel histone deacetylase inhibitor (HDACi), was evaluated in a phase I study of patients with primary myelofibrosis (PMF) and post‐essential thrombocythaemia/polycythaemia vera‐related myelofibrosis (Post‐ET/PV MF). Eighteen patients (PMF 56%; Post‐PV MF 28%; Post‐ET MF 17%) were treated in three cohorts at oral doses of (i) 20, (ii) 30, and (iii) 25 mg three times weekly consecutively. Reversible thrombocytopenia was the dose‐limiting toxicity. Five patients (two in Dose Cohort 1, one in Dose Cohort 2 and two in Dose Cohort 3) received six or more cycles and were evaluable for response assessment. After the sixth cycle, three of these five patients achieved clinical improvement (CI) with 100% reduction in palpable splenomegaly from baseline, and two patients experienced stable disease. Panobinostat therapy was also associated with improvement in the degree of anaemia in two of the five patients. Of the three patients who achieved CI after six cycles, one patient achieved a near complete remission after 15 cycles of treatment and another patient had resolution of marrow fibrosis after 16 cycles. We conclude that panobinostat is a well‐tolerated, clinically active treatment for MF patients, regardless of JAK2 V617F status, and most effective when given at low doses over long periods of time.

High levels of Hsp90 cochaperone p23 promote tumor progression and poor prognosis in breast cancer by increasing lymph node metastases and drug resistance.

p23 is a heat shock protein 90 (Hsp90) cochaperone located in both the cytoplasm and nucleus that stabilizes unliganded steroid receptors, controls the catalytic activity of certain kinases, regulates protein-DNA dynamics, and is upregulated in several cancers. We had previously shown that p23-overexpressing MCF-7 cells (MCF-7+p23) exhibit increased invasion without affecting the estrogen-dependent proliferative response, which suggests that p23 differentially regulates genes controlling processes linked to breast tumor metastasis. To gain a comprehensive view of the effects of p23 on estrogen receptor (ER)-dependent and -independent gene expression, we profiled mRNA expression from control versus MCF-7+p23 cells in the absence and presence of estrogen. A number of p23-sensitive target genes involved in metastasis and drug resistance were identified. Most striking is that many of these genes are also misregulated in invasive breast cancers, including PMP22, ABCC3, AGR2, Sox3, TM4SF1, and p8 (NUPR1). Upregulation of the ATP-dependent transporter ABCC3 by p23 conferred resistance to the chemotherapeutic agents etoposide and doxorubicin in MCF-7+p23 cells. MCF-7+p23 cells also displayed higher levels of activated Akt and an expanded phosphoproteome relative to control cells, suggesting that elevated p23 also enhances cytoplasmic signaling pathways. For breast cancer patients, tumor stage together with high cytoplasmic p23 expression more accurately predicted disease recurrence and mortality than did stage alone. High nuclear p23 was found to be associated with high cytoplasmic p23, therefore both may promote tumor progression and poor prognosis by increasing metastatic potential and drug resistance in breast cancer patients.

HPV Vaccine Acceptability by Latino Parents: A Comparison of U.S. and Salvadoran Populations

STUDY OBJECTIVE To characterize and compare acceptability of human papillomavirus (HPV) vaccination by Latino parents at an urban medical center in the United States and a community hospital in El Salvador. DESIGN After reading an information sheet on HPV, 148 subjects at Bellevue Hospital in New York City and 160 subjects at Hospital Nacional de Santa Gertrudis in San Vicente, El Salvador, completed a survey. Results were analyzed using chi-square, Fishers exact test, and Students t-tests. RESULTS AND CONCLUSIONS Parental acceptance of HPV vaccination was higher in a sample of Salvadoran subjects than in a sample of U.S. Latinas (P<0.001 for daughters and sons). Reasons for objecting to HPV vaccination differ in the two locations. There are important differences between Salvadoran and U.S. subjects. Salvadorans are more accepting of HPV vaccination, and parental acceptance is unlikely to be a barrier to widespread vaccination in El Salvador. Targeted educational materials are needed in both locations.

Lipocalin produced by myelofibrosis cells affects the fate of both hematopoietic and marrow microenvironmental cells

Myelofibrosis (MF) is characterized by cytopenias, constitutional symptoms, splenomegaly, and marrow histopathological abnormalities (fibrosis, increased microvessel density, and osteosclerosis). The microenvironmental abnormalities are likely a consequence of the elaboration of a variety of inflammatory cytokines generated by malignant megakaryocytes and monocytes. We observed that levels of a specific inflammatory cytokine, lipocalin-2 (LCN2), were elevated in the plasmas of patients with myeloproliferative neoplasms (MF > polycythemia vera or essential thrombocythemia) and that LCN2 was elaborated by MF myeloid cells. LCN2 generates increased reactive oxygen species, leading to increased DNA strand breaks and apoptosis of normal, but not MF, CD34(+) cells. Furthermore, incubation of marrow adherent cells or mesenchymal stem cells with LCN2 increased the generation of osteoblasts and fibroblasts, but not adipocytes. LCN2 priming of mesenchymal stem cells resulted in the upregulation of RUNX2 gene as well as other genes that are capable of further affecting osteoblastogenesis, angiogenesis, and the deposition of matrix proteins. These data indicate that LCN2 is an additional MF inflammatory cytokine that likely contributes to the creation of a cascade of events that results in not only a predominance of the MF clone but also a dysfunctional microenvironment.

PP6C Hotspot Mutations in Melanoma Display Sensitivity to Aurora Kinase Inhibition

Recent whole genome melanoma sequencing studies have identified recurrent mutations in the gene encoding the catalytic subunit of serine/threonine phosphatase 6 (PPP6C/PP6C). However, the biochemical, functional, and clinical ramifications of these mutations are unknown. Sequencing PP6C from patients with melanoma (233 primary and 77 metastatic specimens) with extended prospective clinical outcome revealed a large number of hotspot mutations in patients with both primary and metastatic melanoma. Despite minimal association between stage and presence of PP6C mutations in patients with primary melanoma, a subpopulation of cells within each tumor did contain PP6C mutations, suggesting PP6C mutation is an early, but non–tumor-initiating event in melanoma. Among patients with primary melanoma with PP6C mutations, patients with stop mutations had significantly shorter recurrence-free survival compared with patients without stop mutations. In addition, PP6C mutations were independent of commonly observed BRAF and NRAS mutations. Biochemically, PP6C mutations could be classified as those that interact with PP6C regulatory subunits and those that do not. Mutations that did not bind to PP6C regulatory subunits were associated with increased phosphorylation of Aurora kinase, a PP6C substrate, and mitotic defects. However, both classes of PP6C mutations led to increased sensitivity to Aurora kinase inhibition. Together, these data support for the first time that PP6C mutations are molecularly, biochemically, and clinically heterogeneous. Implications: PP6C mutations have distinct functional and clinical consequences in melanoma, and confer sensitivity to Aurora A kinase inhibitors. Mol Cancer Res; 12(3); 433–9. ©2013 AACR.

Three-Year Postoperative Ultrasensitive Prostate-Specific Antigen Following Open Radical Retropubic Prostatectomy Is a Predictor for Delayed Biochemical Recurrence

BACKGROUND Prostate-specific antigen (PSA) is the only independent predictor of biochemical recurrence (BCR) following radical prostatectomy (RP) subject to change over time. OBJECTIVE To determine whether an ultrasensitive PSA measured at 3 yr following RP is a predictor of subsequent BCR. DESIGN, SETTING, AND PARTICIPANTS There were 1197 consecutive men with clinically localized prostate cancer who underwent an open radical retropubic prostatectomy (ORRP) at a tertiary referral academic medical center. Exclusions included 107 men (8.9%) who developed a PSA level ≥ 0.2 ng/ml or underwent hormone therapy or radiation therapy (RT) within the first 3 r after surgery, 191 men (16%) who did not undergo a 3-yr ultrasensitive PSA assay, and 98 men (8.2%) who had PSA levels ≥ 0.1 and <0.2 at 3 yr. The remaining 801 men were stratified into two groups based on their ultrasensitive PSA level at 3 yr postoperatively: group 1, which consisted of patients whose PSA was ≤ 0.04 (n = 765), and group 2, which consisted of patients whose PSA was >0.04 and <0.10 (n = 36). MEASUREMENTS Delayed BCR was the primary end point and represented those men in this cohort who developed a PSA level ≥ 0.2 or underwent salvage RT for a persistently rising PSA level after 3 yr of follow-up. RESULTS AND LIMITATIONS The 7-yr cumulative BCR-free survival rate for groups 1 and 2 was 0.957 (95% confidence interval [CI], 0.920-0.978) and 0.654 (95% CI, 0.318-0.855), respectively. In multivariable Cox proportional hazards models, ultrasensitive PSA level at 3 yr remained the only significant predictor of delayed BCR (likelihood ratio χ(2) for full model: 27.03; df = 1; p < 0.001). A limitation of the study is that no uniform PSA assay was obtained. CONCLUSIONS Our findings provide compelling evidence that an ultrasensitive PSA at 3 yr following RP provides useful insights into delayed BCR and is a source of reassurance for the overwhelming majority of men being followed for delayed recurrences.

A phase II study of panobinostat in patients with primary myelofibrosis (PMF) and post-polycythemia vera/essential thrombocythemia myelofibrosis (post-PV/ET MF).

Myelofibrosis is a chronic and progressive myeloproliferative neoplasm characterized by anemia, splenomegaly, debilitating symptoms and leukemic transformation. Ruxolitinib, an oral JAK1/2 inhibitor, is highly effective in ameliorating systemic symptoms and reducing splenomegaly. Current clinical research is focused on the evaluation of agents based on pre-clinical rationale that can result in disease course modification. Panobinostat is a pan-histone deacetylase inhibitor that has demonstrated clinical activity as a single agent in early phase trials of myelofibrosis. We previously conducted a phase I trial of panobinostat monotherapy in patients with myelofibrosis and determined 25mg thrice weekly as the recommended phase II dose. We then completed an investigator initiated, Simon 2-stage, phase II trial of 22 myelofibrosis patients at our single institution. After 6 cycles of therapy, the overall response rate by IWG-MRT criteria was 36% (8/22; 95% CI: 16-56%). The median percent reduction in spleen volume was 34% (range, 1.6%-73%) in eight evaluable patients. The average reduction in JAK2V617F allele burden was 6.8% (Range; -4.0% to 20.2%) and one patient obtained a complete molecular response. Six patients remained on therapy in the extension phase for a median of 18 months (range, 7-44). Treatment discontinuation was frequent due to patient/physician perception of therapy ineffectiveness. The optimal dosing of panobinostat for the treatment of MF remains somewhat ill-defined but appears to be most effective and better tolerated when administered at lower doses over a prolonged duration of therapy.