Less than three weeks after kicking off a Phase III program for VEGF Trap-Eye in wet age-related macular degeneration, Regeneron Pharmaceuticals Inc. is at it again.

Tarrytown, N.Y.-based Regeneron and partner Sanofi-Aventis Group, of Paris, initiated two Phase III trials with aflibercept - a.k.a. VEGF Trap - in prostate cancer and non-small cell lung cancer (NSCLC). And Regeneron's Chief Scientific Officer George Yancopoulos said that just as VEGF Trap-Eye will compete with Genentech's Lucentis (ranibizumab), the "major competitor" to aflibercept is none other than Lucentis's cousin, Avastin (bevacizumab).

All four drugs inhibit angiogenesis by targeting vascular endothelial growth factor (VEGF), but while Lucentis and Avastin are monoclonal antibodies, VEGF Trap-Eye and aflibercept are VEGF receptor fusion proteins. Regeneron says its drugs allow more potent binding and better VEGF blockade, the clinical significance of which will be tested in the recently initiated Phase III trials.

The Phase III trial of VEGF Trap-Eye, begun earlier this month, will compare various dosing regimens of the drug to Lucentis. Regeneron's goal is to establish noninferiority based on the proportion of wet AMD patients who maintain or improve their vision at the end of one year. The trial is being conducted with partner Bayer HealthCare AG, and its initiation triggered a $20 million milestone payment to Regeneron. (See BioWorld Today, Aug. 6, 2007.)

The Phase III trial of aflibercept in prostate cancer is a double-blind, placebo-controlled study in which 1,200 metastatic, androgen-independent prostate cancer patients will be randomized to receive aflibercept or placebo administered every three weeks in combination with prednisone and Sanofi's Taxotere (docetaxel). The primary endpoint is overall survival, while secondary endpoints include progression free survival, prostate-specific antigen response, pain response, time to occurrence of skeletal related events, safety, pharmacokinetics and immunogenicity.

Yancopoulos said although aflibercept hasn't been tested in a Phase II trial specifically focused on prostate cancer, the "history of anti-VEGF drugs" provides evidence of broad applicability. He also noted that prostate cancer "has not been adequately addressed with anti-VEGF therapy," providing an untapped market opportunity.

Sanofi is keeping mum regarding the details of the NSCLC trial until its Sept. 17 R&D day, and information was not yet posted on ClinicalTrials.gov. According to Regeneron and Sanfi's 2003 partnership, the two companies share worldwide development and commercialization responsibility for the drug, but Sanofi is fronting the costs for the time being. (See BioWorld Today, Sep. 9, 2003 and Dec. 23, 2005.)

Analyst Jim Birchenough of Lehman Brothers Inc. predicted the NSCLC trial will also evaluate aflibercept in combination with Taxotere. The combination will provide differentiation from Avastin, which is approved in combination with carboplatin and Taxol (paclitaxel, Bristol-Myers Squibb Co.) in NSCLC and in combination with intravenous 5-fluorouracil-based chemotherapy in metastatic colorectal cancer.

Colorectal cancer is also on the roster for future aflibercept Phase III trials, as are pancreatic and gastric cancers. The drug is being evaluated in 13 planned or ongoing Phase I and Phase II trials in myelodysplastic syndromes, breast cancer, melanoma and several other types of tumors.

Thus far, the most extensive Phase II aflibercept data presented were in heavily pretreated ovarian cancer patients. The preliminary data showed an 8 percent partial response rate and 77 percent achievement of stable disease. Birchenough said this compares favorably to response rates of 3 to 8 percent with Avastin in a similar patient population, and he argued that a small study showing Avastin to have a 16 percent response rate in ovarian cancer was not an "apples to apples" comparison.

Beyond aflibercept and VEGF Trap-Eye, Regeneron is developing the anti-inflammatory IL-1 Trap drug rilonacept, which is under FDA review for cryopyrin-associated periodic syndrome with a decision expected in November. Regeneron expects to begin a safety and efficacy trial in gout and an exploratory trial in another indication by the end of the year. (See BioWorld Today, June 11, 2007.)

Regeneron also plans to advance the first fully human monoclonal antibody derived from its VelocImmune technology into the clinic in the fourth quarter, with subsequent antibodies to follow at a rate of two per year beginning next year.

Shares of Regeneron (NASDAQ:REGN) fell 23 cents to close at $18.22 on Thursday. That's an improvement over the 52-week low of $13.55 hit earlier this month, but still a ways off the May 52-week high of $28.74.