2004 NOV 22 - (NewsRx.com & NewsRx.net) -- Miravant Medical Technologies (OTCBB:MRVT) announced additional results from analyses of the Photrex (rostaporfin, SnET2) phase III clinical trials, presented at the American Academy of Ophthalmology (AAO) meeting.
Photrex is a proprietary PhotoPoint photodynamic therapy (PDT) drug in development for the treatment of wet age-related macular degeneration (AMD), a leading cause of blindness in older adults. Based on data from two randomized, placebo controlled 2-year trials, clinical investigators reported on:
- Significant visual acuity benefits in Photrex-treated(0.5mg/kg) patients with occult choroidal neovascularization(CNV) lesions;
- Angiographic evidence that Photrex treatments slowed the progression of both classic and occult CNV leakage and fluid accumulation;
- Treatment benefit in Photrex patients regardless of visual acuities (VA) at commencement of treatment, with a greater benefit noted with higher baseline VA;
- Photrex clinical retreatment guidelines based on vessel leakage.
Edgar L. Thomas, MD, Retina-Vitreous Associates, Los Angeles, presented favorable visual acuity (VA) results based on subgroup analyses of lesions with predominantly (greater than or equal to 50%) occult CNV, including pure occult lesions. Statistically significant vision benefits were observed in occult CNV lesions treated per protocol in both the primary and secondary efficacy endpoints. Currently there are no U.S. Food and Drug Administration (FDA)-approved therapies for occult CNV lesions.
The occult VA outcomes were supported by secondary angiographic assessments reported by Ronald P. Danis, MD, University of Wisconsin Fundus Photograph Reading Center, Madison. Photrex-treated lesions (both classic and occult CNV) had statistically significant reductions in vessel leakage and fluid accumulation, factors that are considered to be indicative of AMD disease activity.
Baruch Kuppermann, MD, PhD, University of California, Irvine, presented data on the effect of baseline visual acuity on efficacy at the study endpoint. Analysis of results showed a statistically significant treatment benefit for all baseline VA strata. The greatest relative gain over placebo was noted in patients at highest risk of vision loss, i.e., those with higher VA at the commencement of treatment. Irrespective of baseline VA, patients receiving placebo were approximately 2 times more likely to lose 3 or more lines of vision than treated patients.
Carl Regillo, MD, Wills Eye Hospital, Philadelphia, provided data suggesting Photrex retreatment guidance. During the trials, patients were eligible for retreatment at 3-month intervals. Primary efficacy was assessed in patients who received retreatment when there was evidence of ongoing or increased vessel leakage and compared to patients who did not receive retreatment under those conditions.
At 2 years, patients treated according to the leakage criteria had a statistically significant primary VA benefit. Supporting this finding, angiographic outcomes were statistically significant for these patients at all analysis timepoints over 2 years.
The phase III clinical trials of patients with CNV associated with wet AMD were conducted at 60 U.S. ophthalmology centers. The primary efficacy endpoint for the 2-year studies was the proportion of patients losing less than 15 letters (3 lines) of vision on a standard eye chart.
The secondary efficacy endpoints were mean change in letters loss and patients losing greater than or equal to 30 letters (severe vision loss). Secondary endpoints assessed by fluorescein angiography were areas of overall lesion, choroidal neovascularization, fluorescein leakage and subretinal fluid accumulation.
Wet AMD is a vision-threatening disorder characterized by the growth of abnormal blood vessels (subfoveal choroidal neovascularization, or CNV) at the back of the eye. CNV lesions leak fluid and blood that can lead to severe loss of central vision. Photrex-PDT uses a light-activated drug designed to selectively destroy the abnormal blood vessels and stabilize vision loss. It is estimated that over the next 5 years, 1.35 million people within the U.S. will develop wet AMD, with similar numbers outside the US.
Miravant Medical Technologies (OTCBB:MRVT) is a pharmaceutical development company specializing in PhotoPoint photodynamic therapy.
This article was prepared by Health & Medicine Week editors from staff and other reports. Copyright 2004, Health & Medicine Week via NewsRx.com & NewsRx.net.
