Etoposide as a virocidal anticytomegalovirus therapy: intravitreal toxicology and pharmacology in rabbits

Preclinical Acute Ocular Safety Study of Combined Intravitreal Carboplatin and Etoposide Phosphate for Retinoblastoma

BACKGROUND AND OBJECTIVE

To describe the ocular toxicity of intravitreal carboplatin and etoposide phosphate (VP16P) in Dutch-Belted rabbits.

MATERIALS AND METHODS

Twenty-two adult male Dutch-Belted rabbits (Cohort 1) each received a single, bilateral intravitreal injection (0.05 mL). For Cohort 1, safety was assessed via electroretinograms (ERGs) and ocular examination. Of nine total groups in Cohort 1, the first five received the following single agents: Group 1: normal saline; Group 2: VP16P 75 µg; Group 3: VP16P 100 µg; Group 4: carboplatin 4 µg; and Group 5: carboplatin 8 µg. Groups 6 through 9 received the following combination of carboplatin/ VP16P, respectively: Group 6: 8 µg/75 µg, Group 7: 8 µg/50 µg, Group 8: 4 µg/50 µg, and Group 9: 2 µg/25 µg. Cohort 2 consisted of 15 Dutch-Belted rabbits in seven groups (Groups 10 through 16), each receiving a single, bilateral intravitreal injection. For Cohort 2, safety was assessed via histopathology.

RESULTS

Groups 2 through 8 demonstrated a statistically significant decrease (relative to Group 1) in at least one ERG waveform amplitude obtained 4 weeks postinjection (P < .05). Group 9 (carbo 2 µg/VP16P 25 µg) did not manifest ERG toxicity. Fundoscopic toxicity consisted of slight-to-moderate attenuation of vessels in rabbits receiving doses above carbo 4 µg/VP16P 50 µg. Histopathologic retinal toxicity (Cohort 2) was dose-dependent, ranging from full-thickness atrophy in rabbits receiving the highest dose to normal in rabbits receiving carbo 2 µg/VP16P 25 µg.

CONCLUSIONS

Combined carboplatin and VP16P may be compatible for intravitreal injection therapy, and a single dose of 2 µg/25 µg appears to be safe in a rabbit model. These agents may be a safer alternative to intravitreal melphalan (Alkeran; GlaxoSmithKline, Brentford, United Kingdom) for the treatment of vitreous seeds in retinoblastoma. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:151-159.].

Replication-Competent Influenza Virus and Respiratory Syncytial Virus Luciferase Reporter Strains Engineered for Co-Infections Identify Antiviral Compounds in Combination Screens

Myxoviruses such as influenza A virus (IAV) and respiratory syncytial virus (RSV) are major human pathogens, mandating the development of novel therapeutics. To establish a high-throughput screening protocol for the simultaneous identification of pathogen- and host-targeted hit candidates against either pathogen or both, we have attempted co-infection of cells with IAV and RSV. However, viral replication kinetics were incompatible, RSV signal window was low, and an IAV-driven minireplicon reporter assay used in initial screens narrowed the host cell range and restricted the assay to single-cycle infections. To overcome these limitations, we developed an RSV strain carrying firefly luciferase fused to an innovative universal small-molecule assisted shut-off domain, which boosted assay signal window, and a hyperactive fusion protein that synchronized IAV and RSV reporter expression kinetics and suppressed the identification of RSV entry inhibitors sensitive to a recently reported RSV pan-resistance mechanism. Combined with a replication-competent recombinant IAV strain harboring nanoluciferase, the assay performed well on a human respiratory cell line and supports multicycle infections. Miniaturized to 384-well format, the protocol was validated through screening of a set of the National Institutes of Health Clinical Collection (NCC) in quadruplicate. These test screens demonstrated favorable assay parameters and reproducibility. Application to a LOPAC library of bioactive compounds in a proof-of-concept campaign detected licensed antimyxovirus therapeutics, ribavirin and the neuraminidase inhibitor zanamivir, and identified two unexpected RSV-specific hit candidates, Fenretinide and the opioid receptor antagonist BNTX-7. Hits were evaluated in direct and orthogonal dose-response counterscreens using a standard recRSV reporter strain expressing Renilla luciferase.

Proliferation of lens epithelial cells on the Acrysof intraocular lens: clinical and histological features of a case

Postoperative deposits on the surface of intraocular lenses (IOLs) have been demonstrated in vivo for many IOL material types. The Acrysof acrylic lens develops a granular material extending from the capsulorhexis margin onto the IOL's anterior surface during the first 4 weeks after surgery in a significant proportion of cases. Complete resolution of this membrane occurs by 3 months in almost all cases. The case is presented of an 81-year-old woman who had a persisting membrane coverng the IOL surface at 6 months. This membrane was removed surgically and pathology showed the constituent cells to be of lens epithelial cell origin.