iSONEP Targets SIP in AMD
CLINICAL TRIAL SPOTLIGHT
iSONEP Targets SIP in AMD
Will another cancer drug prove to be effective in treating AMD?
ANDREW E. MATHIS, PhD, MEDICAL EDITOR
Since Philip J. Rosenfeld, MD, PhD, of Bascom Palmer Eye Center in Miami, began using bevacizumab in patients with AMD - if not before then - the treatment of neovascular AMD and resolution of choroidal neovascularization has been linked to the development of treatments designed to prevent metastasis of cancer. Lpath, Inc. of San Diego has contributed sonepcizumab (also known as LT1009 or iSONEP in its ocular formulation) to the growing number of treatments for wet AMD, this one with an eye on S1P, a bioactive lipid that plays a role in several pathologies. Lpath has just finished enrollment of a single-dose phase 1 safety trial that may provide clues as to its efficacy.
Scott R. Pancoast, president and CEO of Lpath, told Retinal Physician, "Growing evidence suggests that the bioactive lipid S1P could contribute to both the early and late stages of maladaptive retinal remodeling associated with wet AMD. Thus, inhibiting the action of S1P could be a novel and effective therapeutic treatment for wet AMD that may offer significant advantages over exclusively anti-VEGF approaches (or act synergistically with them) to address the complex processes and multiple steps that ultimately lead to visual loss."
S1P vs VEGF
As so many treatments for AMD have thus far focused on the role of VEGF, iSONEP is novel in that it has another target. "VEGF inhibitors are an effective means of treating wet AMD, but there is still a major unmet need," Mr. Pancoast explained. 'Lucentis' clinical-trial data show that the average patient who had a successful response to treatment did not regain driving vision or the ability to read without low-vision aids and that 30% of patients actually lost vision. Furthermore, many of these patients were at very early stages of the degenerative process, when visual-acuity improvement potential is greatest, unlike many of the patients who are treated under 'real-world' circumstances outside the clinical-trial environment."
Mr. Pancoast further explained that, while VEGF is an important mediator in the pathogenesis of neovascularization, VEGF is not alone in the process. Vision loss due to wet AMD is not simply the result of subretinal fluid, but also fibrosis, inflammation and wound healing. He stated, "iSONEP exerts multiple mechanisms of action - including profound anti-inflammatory effects, as well as anti-angiogenic, anti-leakage, and anti-fibrotic properties - and thereby holds promise of providing additive therapeutic effects to Lucentis."
THE CANCER CONNECTION
Mr. Pancoast was careful to underscore that the version of sonepcizumab being tested for AMD (ie, iSONEP) is fundamentally different from the version under investigation for advanced solid tumors. The latter version has been dubbed ASONEP, and Mr. Pancoast explained, "While the ASONEP and iSONEP product candidates use the same monoclonal antibody that targets S1P, the product candidates use different formulations and because of this, ASONEP is not appropriate for dosing into the eye and would almost certainly carry a restriction on its label warning of the dangers of such intravitreal administration."
Nevertheless, the oncology trial can provide important information about sonepcizumab. For one thing, ASONEP has been well tolerated in a phase 1 trial at doses as high as 24 mg/kg. As patients with AMD would be receiving one-thousandth of the oncology dose, the safety findings from the oncology trial indicate a very safe profile for ocular use. This is particularly important given the consistent concerns of systemic side effects with the use of bevacizumab and the strong emphasis on detecting any such side effects from ranibizumab as early as possible.
As for results, these will be some time in coming. Since the trial only finished enrolling in the summer, one-year interim safety data will probably not appear until the fall of 2010. Efficacy data will be available fairly soon, however. RP