A Biomarker Study to Evaluate MN-166 (Ibudilast) in Subjects With Amyotrophic Literal Sclerosis (ALS)

This is a multi-center, open-label study of MN-166 (ibudilast) in subjects with ALS. To be
eligible subjects must meet the El Escorial criteria of possible, laboratory-supported
probable, probable, or definite criteria for a diagnosis of ALS. Safety, tolerability, blood,
neuro-imaging biomarkers, and clinical outcomes will be collected on all subjects. Subjects
will receive study drug for 36 weeks.

The study will consist of a Screening Phase (up to 6 weeks), an Open-Label Treatment Phase
(36 weeks) and a Off-Treatment Follow-up Phase (4 Weeks).

During the Screening Phase, eligible ALS subjects will sign an informed consent form and the
following screening assessments will be performed: review of inclusion/exclusion criteria: El
Escorial ALS Diagnostic criteria, medical history and demographics, ALS diagnosis history,
physical and neurological examination, U. Penn upper motor Neuron Burden (UMNB), pulmonary
function tests, vital signs including height and weight, blood for safety labs including TSPO
affinity test, ECG and review and documentation of concomitant medications and therapies.

Screening Phase (up to 6 weeks) The Treatment Phase will consist of a Baseline visit and 3
subsequent clinic visits at Weeks 4, 12, 24, and 36. Telephone follow-ups will occur at Weeks
1, 2, 8, 16, 20, 28, and 32.

Open-Label Treatment Phase (36 weeks) At the Baseline visit, subjects will return to the
clinic and the following assessments will be performed/administered: review of inclusion and
exclusion criteria for continued eligibility, vital signs, blood for safety labs and
biomarkers, ECG, ALSFRS-R questionnaire, slow vital capacity (SVC), baseline strength as
measured by hand held dynamometry (HHD), and Columbia Suicide Severity Rating Scale (C-SSRS).
At this visit, study drug will be dispensed, and adverse events, concomitant medications and
therapies will be assessed and documented. At subsequent visits during the Treatment Phase,
similar assessments will be performed.

In addition, a [11C]PBR28-PET scan will be performed once between the Screening and Baseline
visit, and once between the Week 20 and Week 28 phone calls. The ALSFRS-R, SVC and U Penn
Upper Motor Neuron Burden will be repeated on the same day as the PET scans.

The follow-up visit will consist of a telephone call to document adverse events and
concomitant therapies

Inclusion Criteria:

1. Subjects must be diagnosed as having possible, probable, probable-laboratory
supported, or definite ALS, either sporadic or familial according to modified El
Escorial criteria.

2. Age 18 or above, able to provide informed consent, and safely comply with study
procedures.

3. Vital capacity (VC) of at least 50% predicted value for gender, height and age at
screening visit, or in the opinion of the study physician, able to safely tolerate
study procedures. (Not applicable to flexible arm)

4. Subject must be able to swallow oral medication at the Baseline Visit and expected to
be able to swallow the capsules throughout the course of the study.

5. Subject must not have taken riluzole for at least 30 days, or be on a stable dose of
riluzole for at least 30 days, prior to screening (riluzole-naïve participants are
permitted in the study). (Not applicable to flexible arm)

6. Women must not be able to become pregnant (e.g. post menopausal, surgically sterile,
or using adequate birth control) for the duration of the study and 3 months after
study completion.

7. Males should practice contraception for the duration of the study and 3 months after
completion.

8. Ability to safely lie flat for 90 min for PET procedures in the opinion of the study
physician. (Not applicable to flexible arm)

9. High or mixed affinity to bind TSPO protein (Ala/Ala or Ala/Thr) (see section 7.2.1).
(Not applicable to flexible arm)

10. Upper motor Neuron Burden (UMNB) Score ≥25 (out of 45) at screening visit. (Not
applicable to flexible arm)

Exclusion Criteria:

1. Abnormal liver function defined as AST and/or ALT > 3 times the upper limit of the
normal.

2. Renal insufficiency as defined by a serum creatinine > 1.5 times the upper limit of
normal.

3. The presence of unstable psychiatric disease, cognitive impairment, or dementia that
would impair ability of the participant to provide informed consent, according to PI
judgment.

4. Clinically significant unstable medical condition (other than ALS) that would pose a
risk to the participant if they were to participate in the study.

5. History of HIV, clinically significant chronic hepatitis, or other active infection.

6. Active inflammatory condition of autoimmune disorder (Not applicable to flexible arm)

7. Females must not be lactating or pregnant.

8. Active participation in another ALS clinical trial or exposure to an off label ALS
experimental treatment within 30 days of the Baseline Visit (Not applicable to
flexible arm)

9. Exposure to immunomodulatory medications within 30 days of the Baseline Visit. (Not
applicable to flexible arm)

10. Any contraindication to undergo MRI studies such as

- History of a cardiac pacemaker or pacemaker wires

- Metallic particles in the body

- Vascular clips in the head

- Prosthetic heart valves

- Claustrophobia (Not applicable to flexible arm)

11. Radiation exposure that exceeds the site's current guidelines (Not applicable to
flexible arm)

12. EKG finding of QTc prolongation > 450 ms for males and > 470 ms for females at
screening or baseline.

13. Not on any prohibitive medication or known QT prolonging medication: