WTF: The Runup on Elan Continues
Presumably powered on expectations about bapineuzumab and its phase 3 results—which are expected to be released later this year (possibly at the AAIC in mid-July). But see Adam Fuerstein’s article of March 19th for an appropriate, cautionary reminder.
Bapineuzumab, an anti-amyloid MAb, has been codeveloped by Pfizer and JNJ (or really, Janssen), along with original co-owner Elan,* and the drug performed marginally (if at all) in earlier phase 2 studies of patients with AD. The bottom line: the MAb targets amyloid and removes it (or targets it for immune-mediated removal), but this mechanism doesn’t appear to be associated with clinical improvement. Specifically enrollees who were APOE ε4 carriers (meaning those enrollees at greater risk of AD and who probably have a greater amyloid burden) didn’t benefit as much (if at all) as APOE ε4 non-carriers—a finding that patently contradicts the rationale for targeting amyloid in the first place.
Last bapineuzumab has been associated with brain edema in about 17% of patients (a phenomenon that has been dubbed ARIA-E), and this edema was more likely in APOE ε4 carriers (again, those patients who probably have a greater amyloid burden) and when using the highest bapineuzumab dosage (which was discontinued for phase 3). The mechanism by which bapineuzumab—and other anti-amyloid compounds, for that matter—cause edema is unclear; however, one compelling explanation is through the removal of vascular amyloid, which results in leaky vessels.
And yet the seemingly mindless runup on Elan stock continues, just like it did (albeit less robustly) in 2008 before the disappointing phase 2 results were presented. The share price is now, in fact, at a 3-year high.
* The original co-developers of bapineuzumab were Elan and Wyeth, which were respectively bought up by Janssen and Pfizer. Janssen and Pfizer then formed the Alzheimer’s Immunotherapy Program (AIP), the putative darling of which is bapineuzumab.
AAIC = Alzheimer’s Association International Conference; AD = Alzheimer’s disease; APOE = gene encoding apolipoprotein E; MAb = monoclonal antibody.