PRISM: Efficacy and Safety of Cobomarsen (MRG-106) in Subjects With Mycosis Fungoides Who Have Completed the SOLAR Study

Progression-free survival

Time from date of first dose of cobomarsen until the date of earliest documented progression or death from any cause.

Time frame: Up to approximately 36 months (estimated study duration)

Pruritis Numerical Rating Scale

Measures the patient's degree of itch related to mycosis fungoides based on an 11-point scale (from 0-10), with 0 being no itch and 10 being worst imaginable itch.

Time frame: Daily for up to 6 months, then weekly up to approximately 36 months (estimated study duration)

Skindex-29 Dermatological Survey

Measures the effects of skin disease on quality of life based on a 30-item questionnaire. The patient's responses are transformed to a linear scale from 0 to 100 and averaged to determine a subscore in three domains (Symptoms, Emotions and Functioning), as well as a total score. Lower scores indicate a lesser degree of skin disease interference with quality of life.

Time frame: Monthly, up to approximately 36 months (estimated study duration)

Pain Numerical Rating Scale

Measures the patient's intensity of pain related to mycosis fungoides based on an 11-point scale (from 0-10), with 0 being no pain and 10 being worst imaginable pain.

Time frame: Daily, for up to 6 months, then weekly up to approximately 36 months (estimated study duration)

Difference in drug tolerability by Patient Impression of Treatment Side Effects

Time frame: Weekly, up to approximately 36 months (estimated study duration)

Duration of composite global response for responding subjects

Time frame: Up to approximately 36 months (estimated study duration)

Complete response rate

Based on composite global response criteria including radiological imaging, flow cytometry, and mSWAT.

Time frame: Up to approximately 36 months (estimated study duration)

Skin disease severity based on modified Severity-weighted Assessment Tool (mSWAT)

Measures skin disease severity based on the percentage of skin within each body region with patches, plaques, or tumors. Total scores are calculated by adding the total percent for each category of lesion (patch, plaque, or tumor) and multiplying by a weighting factor. Weighted subtotals are added together to obtain the total score. Lower scores indicate a lower degree of skin disease severity.

Time frame: Monthly, up to approximately 36 months (estimated study duration)

Time to progression

Time from date of first dose of cobomarsen until the earliest date of confirmed progression.

Time frame: Up to approximately 36 months (estimated study duration)

Overall survival

Time from date of first dose of cobomarsen until the date of death from any cause.

Time frame: Up to approximately 36 months (estimated study duration)

Number of participants with treatment-related adverse events as assessed by CTCAE v5.0

Time frame: Up to approximately 36 months (estimated study duration)

Plasma concentration of cobomarsen

Sparse pharmacokinetic samples will be collected to monitor for accumulation of cobomarsen.

Time frame: Day 1, Day 29 and monthly or every other month thereafter until End of Treatment visit, up to approximately 36 months (estimated study duration)