Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of IONIS-MAPTRx in Patients With Mild Alzheimer's Disease

Inclusion Criteria for Part 1: * Males or females aged 50-74 years, inclusive, at the time of informed consent * Diagnosed with mild Alzheimers disease, including CSF biomarkers consistent with this diagnosis * Body Mass Index BMI ≥ 18 and ≤ 35 kg/m2 and total body weight \> 50 kg (110 lbs) * Able and willing to meet all study requirements, including toleration for MRI scans, blood draws and lumbar punctures, travel to Study Center and participation in all procedures and measurements at study visits * Have a trial partner who is reliable, competent and at least 18 years of age, is willing to accompany the patient to select trial visits and to be available to the Study Center by phone if needed * Reside within 4 hours travel of the Study Center Exclusion Criteria for Part 1: * Treatment with another Study Drug, biological agent, or device within one-month of Screening or 5 half-lives of investigational agent, whichever is longer * Clinically significant medical condition which would make the patient unsuitable for inclusion or could interfere with the patient participating in or completing the study * Use of a disallowed CNS-active or antipsychotic medication within 4 weeks prior to Screening punctures Inclusion Criteria for Part 2: * Must have completed the Treatment Evaluation and Post-Treatment Periods in Part 1 Exclusion Criteria for Part 2 (only applicable to participants in Cohorts A and B, as participants from Cohorts C and D will seamlessly transition to Part 2): * Treatment with another Study Drug, biological agent, or device within one-month of Screening or 5 half-lives of investigational agent, whichever is longer * Clinically significant medical condition which would make the patient unsuitable for inclusion or could interfere with the patient participating in or completing the study * Use of a disallowed CNS-active or antipsychotic medication within 4 weeks prior to Screening punctures