MacroGenics Provides Phase 2 TAMARACK Study Early Interim Safety Data and Plans for Future Disclosures - Seite 2

Methods
TAMARACK is an ongoing randomized, open-label, Phase 2 dose selection study assessing the efficacy, safety, and tolerability of two dose levels of vobra duo (2.0 mg/kg and 2.7 mg/kg IV Q4W). The study enrolled patients (pts) with mCRPC previously treated with abiraterone, enzalutamide, or apalutamide; prior docetaxel was allowed. The primary endpoint is investigator-assessed PFS at 6 months.

Results
At data cutoff (Jan 4, 2024), 182 pts with mCRPC enrolled on TAMARACK, of which 177 received vobra duo. Enrolled pts were 46 to 89 years of age (median 70.5) with ECOG performance status ≤ 2. Thirty (16.5%) had visceral disease at baseline, 109 (59.9%) had RECIST-evaluable disease, and 98 (53.8%) received prior docetaxel. At this early data cut, pts have received a median of 3 (range 1 to 7) cycles of vobra duo; treatment is ongoing in 156 (85.7%). A summary of treatment-emergent adverse events (TEAEs) is presented below.

	Vobra duo 2.0 mg/kg (n=91)	Vobra duo 2.7 mg/kg (n=86)
Any TEAE	85 (93.4%)	82 (95.3%)
TEAE Grade ≥ 3	23 (25.3%)	27 (31.4%)
Serious AE	11 (12.1%)	17 (19.8%)
Drug Interruption due to AE	10 (11.0%)	16 (18.6%)
Drug Discontinuation due to AE	4 (4.4%)	2 (2.3%)
Fatal AE	0	0

The most common (≥10%) TEAEs regardless of dose were asthenia (40.7%), nausea (27.7%), fatigue (20.3%), decreased appetite (19.2%), anemia (17.5%), constipation (16.4%), diarrhea (14.7%), headache (13.0%), neutropenia (12.4%), and peripheral edema (10.7%). In the subset (n = 95) of TAMARACK pts on treatment for ≥ 12 weeks or who discontinued study treatment within 12 weeks, TEAEs led to drug interruption in 12 (12.6%) and discontinuation in 5 (5.3%) pts. This compares favorably to the rate of drug interruption (58.5%) and discontinuation (14.6%) observed at 12 weeks in pts with mCRPC who received vobra duo at 3.0 mg/kg Q3W on the Phase 1 study. Following the pre-specified interim analysis for futility on both arms, the IDMC recommended continuing the study as planned without modification.