An Open-Label Extension of XPro1595 in Patients With Alzheimer's Disease

The goal of this Phase 2 Open Label study is to evaluate long-term safety, tolerability, and efficacy of XPro1595 on measures of cognition, function and brain quality in individuals with Alzheimer's Disease.

This study is designed as a Phase 2, open label study investigating the safety, tolerability, and efficacy of XPro1595 in patients with Alzheimer's Disease (AD). The planned dose is 1.0 mg/kg of XPro1595 for all subjects that completed a previous Phase 1 or Phase 2 study with XPro1595.

Each enrolled patient will be treated with 1.0 mg/kg of XPro1595 as a subcutaneous injection once a week for 55 or 74 weeks, for a total exposure to XPro1595 of up to 78 weeks (18 months), depending on their previous study. Blood sampling for clinical lab analyses, physical exam findings, ECG and C-SSRS will be collected throughout the study to assess the safety and tolerability of XPro1595. Imaging endpoints (MRI), blood sampling for neuroinflammatory and neurodegenerative biomarkers, clinical ratings (CDR-SB, ADCS-MCI ADL, NPI-12) and cognitive performance assessed via the EMACC will be collected at screening and at Weeks 12, 24, 36, and 48. Depending on the parent study, some or all of these assessments may also be made at Weeks 55, 60 or 74.

All patients that completed 4 weeks of dosing and the week 5 PK draw in the Phase 1 PK Lead-In or completed the treatment period and End of Study (EOS) assessments in a Phase 2 study are eligible to enroll into the OLE study. All patients enrolled, including those treated with placebo in the parent study, will receive 1.0 mg/kg XPro1595. Randomized treatment will remain blinded until the parent study database is locked, the study is unblinded and results for their prior study are released.

Eligibility Criteria:
Inclusion Criteria:

Patients are eligible to be included in the study only if all the following criteria apply:

1. Participated and completed the full duration of the study intervention and all procedures at the End of Study (EOS) visit in a previous XPro1595 study.
2. Concomitant medications for the management of MCI/AD and/or behavior symptoms which were ongoing during the double-blind study should remain at a constant dose throughout this study.
3. Patient must be willing and able to provide informed consent prior to any study procedures being performed. If the patient is not competent, a LAR (Legally Authorized Representative) must provide informed consent on their behalf, and the patient must provide assent.
4. Has a study partner willing to participate for the duration of the trial who either lives in the same household or interacts with the patient at least 4 hours per day and on at least 4 days per week, who is knowledgeable about the patient's daytime and night-time behaviors and who can be available to attend all clinic visits in person at which informant assessments are performed. This study partner should agree to monitor and report on concomitant medications, understand the study requirements, and assist the participant in meeting study requirements. Patients with study partners that do not meet this criterion but are determined by the investigator as able to provide an adequate assessment of the patient may also participate with prior approval from the sponsor (However, this is not a requirement for patients coming from the AD-02 PK Lead-In Study).
5. All male subjects who are sexually active with a female of childbearing potential (FCBP) must agree to use a highly effective method of contraception during the treatment period and until 90 days after the last dose of treatment.
6. All females of childbearing potential (FCBP) must have a negative urine pregnancy test and agree to use a highly effective method of contraception during the treatment period and 30 days after the last dose of treatment.

Exclusion Criteria:

1. Any clinically significant abnormalities that in the opinion of the Investigator require further investigation or treatment or may interfere with study procedures and assessments or affect patient safety. These include but are not limited to, laboratory tests, electrocardiogram (ECG), physical examination, or vital signs at Screening or other medical conditions (e.g., cardiac, respiratory, gastrointestinal, psychiatric, renal disease) which are not adequately and stably controlled.
2. Unable to comply with the study procedures and assessments.