There are approximately
9200 PALS in Japan at any given time. The healthcare system in Japan differs
greatly from that in other countries, however, the reality of ALS remains the
same – no effective treatment, no cure. Recently, a phase 2/3 clinical trial of
mecobalamin (aka E0302) was completed in Japan in people diagnosed with ALS. The clinical trials were sponsored by Eisai
Pharmaceuticals, a Japanese based biopharmaceutical research and manufacturing
company. The clinical
study was done in Japan only, with 370 PALS enrolled across
more than 40 different enrollment centers across the island nation. The results
of the study were recently
presented at the American Academy of
Neurology meeting in Philadelphia.
The were no significant
differences between groups in the primary endpoints of survival and ALS
Functional Rating Scale-Revised (ALSFRS-R) scores. However, post hoc
analysis revealed that ultra-high dose injections of mecobalamin may have
demonstrated efficacy in patients who enrolled in the trial shortly after
diagnosis
Based on its analysis
of the clinical trial data, Eisia announced it had filed a New Drug Application
before the Japanese Pharmaceuticals and Medical Devices Agency at the end of
May 2015. If approved, mecobalamin could then be recognized as a treatment for ALS
in Japan.
What
is mecobalamin and why test it in PALS?
Mecobalamin
is approved and marketed in Japan as Methycobal® for the treatment of
peripheral neuropathies and megaloblastic anemia cause by vitamin B12
deficiency. In general, vitamin B12 has been
shown to display some neuroprotective properties. In this clinical study, an injectible version of the B12 compound was used.
According to Eisai, the exact mechanism of action by which mecobalamin may
apply to ALS is not known. However, the company believes that the compound may
have efficacy through its neuroprotective effects and the role it may play in
the regeneration of nerve axons. The doses of mecobalamin used in the ALS
clinical trials were 50X and 100X greater than the currently approved dose of
mecobalamin, which is why they are referred to as “ultra-high" doses in the
clinical studies.
Who
enrolled?
The
clinical trial began enrolling Japanese PALS in 2007 and completed in 2014.
According to published information, 373 people diagnosed with definite or
probable ALS were screened by Eisai investigators, 370 were enrolled in the
trial. Overall, the enrollment criteria for the trial were standard,
meaning PALS with onset more than 3 years ago, or those having a tracheotomy or
using NIPPV device were excluded from enrollment screening. In total, 123 PALS
were placed in a high-dose cohort (50mg twice a week), 124 in a low-dose cohort
(25mg twice a week), and the remaining 123 in the trial’s placebo treatment
arm. Each treatment was delivered at a trial clinic via intramuscular
injections. All those enrolled in the program were asked to continue on the
treatment for 3.5 years (a total of 182 weeks and 365 potential treatments per
PALS), therefore, the willingness and ability to travel to one of the 43
treatment sites twice a week in Japan was a requirement for enrollment.
What
were the results of this study?
The
study set out with clear primary endpoints in mind, namely to confirm the
safety of mecobalamin and to investigate potential efficacy in people diagnosed
with ALS. The study met its safety endpoints without issue, reporting no
significant adverse events. Regarding efficacy, the study’s results were less
straight-forward. While there was no efficacy endpoint reached overall for
either dose, when the investigator’s conducted a post hoc analysis of cohorts
based on months from onset, they discovered a positive signal in PALS who
started in the high-dose cohort within 12 months of their first symptoms.
According to the study’s post hoc analysis, patients who were diagnosed with
ALS within 12 months of symptom onset in the 25mg cohort experienced the
greatest potential benefit. The Lead Investigator of the study has suggested
that while this outcome is encouraging, making an ALS diagnosis within the
first 12 months of symptom onset can be a challenge.
Bottom
line
This
clinical trial was well organized and executed. Its results are clear;
ultra-high doses of a formulation of B12, called mecobalamin, were found to be
safe and well tolerated in PALS for a very long period of exposure (3.5 years). While the study did not
reach its overall efficacy endpoints, a post hoc analysis suggested that a
specific cohort of PALS – those enrolled closet to their original onset of symptoms and put on the 25mg dose of mecobalamin experienced
a potential effect on disease progression and/or survival. Based on this data,
Eisai filed a New Drug
Application at the end of May 2015 for the use of mecobalamin for the
treatment of ALS in Japan. It is not known whether or not Eisai will
conduct clinical research or pursue filings in other countries at this time.
The
ALS Therapy Development Institute will continue to monitor this work closely,
including whether or not the Japanese Drug Regulatory Agency approves Eisai’s
application to register mecobalamin as a treatment for ALS in that country. In
is important to acknowledge that this version of B12 is not the same as what is
found on the shelves at your local pharmacy. However, several compounding
pharmacies and others in the United States do regularly make this version of
the vitamin available with a prescription from an attending physician or other
qualified medical professional.
Resources:
Poster
Presentation at AAN
Press Release from Eisai