Joan M. O'Brien

Mutations in GNA11 in Uveal Melanoma

BACKGROUND Uveal melanoma is the most common intraocular cancer. There are no effective therapies for metastatic disease. Mutations in GNAQ, the gene encoding an alpha subunit of heterotrimeric G proteins, are found in 40% of uveal melanomas. METHODS We sequenced exon 5 of GNAQ and GNA11, a paralogue of GNAQ, in 713 melanocytic neoplasms of different types (186 uveal melanomas, 139 blue nevi, 106 other nevi, and 282 other melanomas). We sequenced exon 4 of GNAQ and GNA11 in 453 of these samples and in all coding exons of GNAQ and GNA11 in 97 uveal melanomas and 45 blue nevi. RESULTS We found somatic mutations in exon 5 (affecting Q209) and in exon 4 (affecting R183) in both GNA11 and GNAQ, in a mutually exclusive pattern. Mutations affecting Q209 in GNA11 were present in 7% of blue nevi, 32% of primary uveal melanomas, and 57% of uveal melanoma metastases. In contrast, we observed Q209 mutations in GNAQ in 55% of blue nevi, 45% of uveal melanomas, and 22% of uveal melanoma metastases. Mutations affecting R183 in either GNAQ or GNA11 were less prevalent (2% of blue nevi and 6% of uveal melanomas) than the Q209 mutations. Mutations in GNA11 induced spontaneously metastasizing tumors in a mouse model and activated the mitogen-activated protein kinase pathway. CONCLUSIONS Of the uveal melanomas we analyzed, 83% had somatic mutations in GNAQ or GNA11. Constitutive activation of the pathway involving these two genes appears to be a major contributor to the development of uveal melanoma. (Funded by the National Institutes of Health and others.).

Phase I Study of Intraventricular Administration of Rituximab in Patients With Recurrent CNS and Intraocular Lymphoma

PURPOSE We previously determined that intravenous administration of rituximab results in limited penetration of this agent into the leptomeningeal space. Systemic rituximab does not reduce the risk of CNS relapse or dissemination in patients with large cell lymphoma. We therefore conducted a phase I dose-escalation study of intrathecal rituximab monotherapy in patients with recurrent CNS non-Hodgkins lymphoma (NHL). PATIENTS AND METHODS The protocol planned nine injections of rituximab (10 mg, 25 mg, or 50 mg dose levels) through an Ommaya reservoir over 5 weeks. The safety profile of intraventricular rituximab was defined in 10 patients. RESULTS The maximum tolerated dose was determined to be 25 mg and rapid craniospinal axis distribution was demonstrated. Cytologic responses were detected in six patients; four patients exhibited complete response. Two patients experienced improvement in intraocular NHL and one exhibited resolution of parenchymal NHL. High RNA levels of Pim-2 and FoxP1 in meningeal lymphoma cells were associated with disease refractory to rituximab monotherapy. CONCLUSION These results suggest that intrathecal rituximab (10 to 25 mg) is feasible and effective in NHL involving the CNS.

Developmental rescue of an embryonic-lethal mutation in the retinoblastoma gene in chimeric mice.

The requirement for a functional retinoblastoma gene, Rb‐1, in murine development around days 12‐15 of gestation precludes monitoring the effect of loss of Rb‐1 function on later stages of development and on tumorigenesis in adult mice. Here we describe the developmental rescue of embryonic stem cells carrying two inactive Rb‐1 alleles in chimeric mice. Rb‐1‐ cells contributed substantially to most tissues in adult chimeras, including blood, liver and central nervous system, which were severely affected in pure Rb‐1‐ embryos. The adult chimeric erythroid compartment appeared completely normal, but an increased number of nucleated red cells was observed during fetal liver erythropoiesis in highly chimeric embryos. No ostensive abnormalities were seen in the developing and adult CNS. However, the developing retina of chimeric Rb‐1‐ embryos showed ectopic mitoses and substantial cell degeneration, while the contribution of Rb‐1‐ cells to the adult retina was much reduced. Moreover, the formation of lens fibre cells was severely disturbed. No retinoblastomas developed in any of these mice. Instead, nearly all animals died of pituitary gland tumours which were exclusively derived from Rb‐1‐ cells.

Retinoblastoma: One World, One Vision

Retinoblastoma is curable when diagnosed early and treated appropriately; however, the prognosis is dismal when the basic elements of diagnosis and treatment are lacking. In developing countries, poor education, lower socioeconomic conditions, and inefficient health care systems result in delayed diagnosis and suboptimal care. Furthermore, the complexity of multidisciplinary care required is seldom possible. Whereas ocular salvage is a priority in the Western world, death from retinoblastoma is still a major problem in developing countries. To bring the 2 ends of this spectrum together and provide a forum for discussion, the “One World, One Vision” symposium was organized, at which clinicians and researchers from various cultural, geographic, and socioeconomic backgrounds converged to discuss their experiences. Strategies for early diagnosis in developing countries were discussed. Elements of the development of retinoblastoma centers in developing countries were discussed, and examples of successful programs were highlighted. An important component in this process is twinning between centers in developing countries and mentor institutions in high-income countries. Global initiatives by nongovernmental organizations such as the International Network for Cancer Treatment and Research, Orbis International, and the International Agency for Prevention of Blindness were presented. Treatment of retinoblastoma in developing countries remains a challenge; however, it is possible to coordinate efforts at multiple levels, including public administrations and nonprofit organizations, to improve the diagnosis and treatment of retinoblastoma and to improve the outcome for these children.

Ultrasound biomicroscopy: role in diagnosis and management in 130 consecutive patients evaluated for anterior segment tumours

Background/aim: Ultrasound biomicroscopy (UBM) is an important tool for assessing anterior segment pathology. This study sought to evaluate UBM in the management of anterior segment tumours. Methods: Retrospective analysis of medical records of consecutive patients referred to the ocular oncology unit, University of California San Francisco (UCSF), for suspected anterior segment tumours from 1999 to 2004. Results: 132 eyes from 130 patients were evaluated, including 55 uveal melanomas (UM), 21 iris naevi, 30 iris cysts, and 26 remaining lesions. Of the melanomas, 45 were also evaluated with conventional A/B-scan. There was 29% correspondence between the anatomical structures invaded by melanoma as identified by B-scan v disease extent defined by UBM. Ciliary body and peripheral iris involvement by melanomas was significantly more frequently observed by UBM than B-scan. Seven of 30 benign cysts were diagnosed as cystic before UBM evaluation. In three cases, neuroepithelial cysts were associated with intercurrent pathology including iris naevus (n = 2) and ciliary body melanoma (n = 1). Two ciliary body melanomas showed cavitation, including one patient with a pseudocyst. Histopathological correlation was possible in six cases. Conclusion: UBM is an indispensable tool for the management of anterior segment tumours. This study demonstrates the superiority of UBM v conventional B-scan for the precise localisation of uveal melanoma, especially involving the ciliary body and peripheral iris.

Immunochemotherapy with Intensive Consolidation for Primary CNS Lymphoma: A Pilot Study and Prognostic Assessment by Diffusion-Weighted MRI

Purpose: We evaluated a novel therapy for primary central nervous system lymphoma (PCNSL) with induction immunochemotherapy with high-dose methotrexate, temozolomide, and rituximab (MT-R) followed by intensive consolidation with infusional etoposide and high-dose cytarabine (EA). In addition, we evaluated the prognostic value of the minimum apparent diffusion coefficient (ADCmin) derived from diffusion-weighted MRI (DW-MRI) in patients treated with this regimen. Experimental Design: Thirty-one patients (median age, 61 years; median Karnofsky performance score, 60) received induction with methotrexate every 14 days for 8 planned cycles. Rituximab was administered the first 6 cycles and temozolomide administered on odd-numbered cycles. Patients with responsive or stable central nervous system (CNS) disease received EA consolidation. Pretreatment DW-MRI was used to calculate the ADCmin of contrast-enhancing lesions. Results: The complete response rate for MT-R induction was 52%. At a median follow-up of 79 months, the 2-year progression-free and overall survival were 45% and 58%, respectively. For patients receiving EA consolidation, the 2-year progression-free and overall survival were 78% and 93%, respectively. EA consolidation was also effective in an additional 3 patients who presented with synchronous CNS and systemic lymphoma. Tumor ADCmin less than 384 × 10–6 mm2/s was significantly associated with shorter progression-free and overall survival. Conclusions: MT-R induction was effective and well tolerated. MT-R followed by EA consolidation yielded progression-free and overall survival outcomes comparable to regimens with chemotherapy followed by whole-brain radiotherapy consolidation but without evidence of neurotoxicity. Tumor ADCmin derived from DW-MRI provided better prognostic information for PCNSL patients treated with the MTR-EA regimen than established clinical risk scores. Clin Cancer Res; 18(4); 1146–55. ©2012 AACR.

Subconjunctival Topotecan in Fibrin Sealant in the Treatment of Transgenic Murine Retinoblastoma

PURPOSE To test the effects of subconjunctival topotecan (TPT) in fibrin sealant (FS) in transgenic murine retinoblastoma (RB). METHODS Growth inhibitory, apoptotic, and cell cycle effects of TPT were assayed in human RB cell lines. In a dose-escalation study, eight groups of three 10- to 14-week-old wild-type mice were treated bilaterally with a single 30-microL injection of subconjunctival TPT in FS (0.025, 0.05, 0.1, 0.2, 0.4, 0.8, 1.6, or 3.2 mg/mL). Two groups of twenty 10-week-old LHbeta-Tag transgenic mice were then treated in the right eye only with TPT in FS (3.2 mg/mL in 30 microL; 0.1-mg total dose) or with FS only. The contralateral eye in each group was left untreated to serve as an internal control. After 3 weeks, ocular tumor burden was determined by histologic examination. RESULTS At 48 hours, IC(50) values of TPT in Y79 and Weri-Rb1 RB cell lines were 35 nM and 50 nM, respectively. Growth inhibitory effects were correlated with increased apoptosis and accumulation of cells in G2. Cytotoxicity of TPT was comparable in aqueous media and in FS. In the dose-escalation study, no histopathologic evidence of ocular toxicity was observed at any dose. Clinical toxicities (mild enophthalmos and eyelid alopecia) were observed only at the highest dose tested (3.2 mg/mL). In the treatment study, both eyes of TPT-treated mice demonstrated significant reduction in tumor burden compared with both eyes of mice treated with FS only (59% reduction; P = 0.04). In mice treated with TPT, tumor burden in TPT-treated eyes and in untreated contralateral eyes did not differ significantly. CONCLUSIONS Subconjunctival administration of TPT in FS to one eye allows the formation of a TPT depot sufficient for an effect to occur 3 weeks after treatment. This effect -- bilateral reduction in tumor burden without a significant difference in treated versus untreated eyes -- suggests that the major route of drug delivery in this system is hematogenous rather than transscleral.

Evaluation of the In vitro and In vivo Antitumor Activity of Histone Deacetylase Inhibitors for the Therapy of Retinoblastoma

Purpose: To evaluate the potential utility of histone deacetylase inhibitors (HDACi) for treatment of retinoblastoma (RB). Experimental Design: Growth-inhibitory effects of HDACi [trichostatin A (TSA), suberoylanilide hydroxamic acid (SAHA), or MS-275] were assessed in human and transgenic murine RB cells. Effects of TSA and MS-275 were also assessed in combination with standard therapeutic agents for RB. Proapoptotic effects of MS-275 and TSA were evaluated by caspase-3/7 activity, Annexin V translocation, and/or Bim expression analyses. Effects of MS-275 on cell cycle distribution and reactive oxygen species levels were determined by flow cytometry. Retinal tissue morphology was evaluated in mice after local administration of MS-275. Analysis of retinal acetyl-histone levels was used to assess MS-275 delivery after systemic administration. Therapeutic effects of MS-275 were determined in transgenic mouse and rat ocular xenograft models of RB after i.p. injection of 20 mg/kg every other day for 21 or 13 days, respectively. Results: TSA, SAHA, and MS-275 dose dependently reduced RB cell survival. TSA and MS-275 showed additive growth-inhibitory effects in combination with carboplatin, etoposide, or vincristine. TSA and MS-275 increased caspase-3/7 activity. MS-275 increased Annexin V membrane translocation and induced G1 arrest. Cytotoxicity of MS-275 was dependent on increased reactive oxygen species levels and was reversed by antioxidant pretreatment. Intraocular administration of 1 μL of 10 μmol/L MS-275 did not alter ocular tissue morphology. Increased acetyl-histone levels confirmed MS-275 delivery to retinal tissue after systemic administration. MS-275 significantly reduced tumor burden in both mouse and rat models of RB. Conclusions: HDACi should be considered for clinical trials in children with RB.

Differential microRNA-34a expression and tumor suppressor function in retinoblastoma cells.

PURPOSE The role of miR-34a, a p53-regulated microRNA, in retinoblastoma (RB) was investigated. METHODS The expression of miR-34 family members in RB cells was determined by semiquantitative RT-PCR and real-time qPCR. Regulation of miR-34a expression by p53-activating compounds was determined by qPCR analysis. The tumor suppressor functions of miR-34a in RB cell lines were determined by tetrazolium-based cell growth assay and by caspase-3/7 and activated caspase-3 apoptotic activity assays. Additive growth inhibitory properties of miR-34a in combination with topotecan were determined by cell growth assay. miR-34a targets in RB cells were identified by real-time qPCR expression analysis of previously reported and GenMiR++-predicted mRNAs. RESULTS Differential miR-34a and miR-34b expression was observed in RB cell lines and tumor samples. miR-34a expression could be increased in Y79 cells, but not Weri-Rb1 cells, after p53 activation. This differential regulation was not caused by genomic alterations at the miR-34a p53 binding site or mature gene. Exogenous miR-34a inhibited Y79 and Weri-Rb1 cell growth and increased apoptotic activity in Y79 cells. Increased inhibition of Y79 and Weri-Rb1 cell growth was observed with combination miR-34a and topotecan treatment. mRNA expression changes were observed in 7 of 7 previously reported and 13 of 18 GenMiR++-predicted miR-34a targets after transfection of Y79 cells with miR-34a compared with negative control microRNA. CONCLUSIONS miR-34a functions as a tumor suppressor in RB cells and is a potential therapeutic target. Differential expression, regulation, and activity of miR-34a in RB cells may suggest further p53 pathway inactivation in RB.

Trilateral retinoblastoma: potentially curable with intensive chemotherapy.

Trilateral retinoblastoma has been lethal in virtually all cases previously reported. We describe a series of 13 patients treated with intensive chemotherapy, defined as the intention to include high‐dose chemotherapy with autologous hematopoietic stem cell rescue.