MacroGenics Releases New Phase 2 TAMARACK Study Data on Vobra Duo for mCRPC at ESMO 2024

MacroGenics, Inc., a biopharmaceutical firm headquartered in Rockville, Maryland, has unveiled updated efficacy and safety data from the Phase 2 TAMARACK study of vobramitamab duocarmazine (commonly referred to as vobra duo). This antibody-drug conjugate (ADC) targets B7-H3 and is being tested for its effectiveness in patients with metastatic castration-resistant prostate cancer (mCRPC). The findings were presented in a poster session at the European Society for Medical Oncology (ESMO) Congress held in Barcelona, Spain, from September 13-17, 2024.

The TAMARACK study was designed to explore whether reducing the starting dose of vobra duo from 3.0 mg/kg to either 2.0 or 2.7 mg/kg and extending the dosing interval from three weeks to four weeks could improve safety, tolerability, and treatment duration. Dr. Scott Koenig, President and CEO of MacroGenics, emphasized that the goal was to achieve better radiographic progression-free survival (rPFS) compared to results from the Phase 1 study. Dr. Koenig noted that the recent findings further support the potential of vobra duo in treating prostate cancer. Future development decisions will depend on comprehensive safety and efficacy data expected by early 2025, alongside considerations of the competitive treatment landscape and resource allocation.

The TAMARACK trial enrolled 181 participants, with 176 receiving at least one dose of vobra duo at either 2.0 mg/kg or 2.7 mg/kg every four weeks. As of the latest data cut-off on July 9, 2024, 23 participants in the 2.0 mg/kg cohort and 16 in the 2.7 mg/kg cohort remained on treatment. While new doses are no longer being administered, participants are still being monitored for adverse events, disease progression, and survival outcomes.

The study's baseline characteristics were detailed, and efficacy results up to the July cut-off date indicate that vobra duo shows antitumor activity in mCRPC. This conclusion is supported by the primary endpoint of 6-month rPFS rate and other tumor response measures.

Safety data up to July 9, 2024, were also summarized, highlighting the incidence of adverse events and overall tolerability.

The poster titled "TAMARACK: Randomized Phase 2 trial of the B7-H3 targeting antibody drug conjugate (ADC) vobramitamab duocarmazine (vobra duo) in metastatic castration-resistant prostate cancer (mCRPC)" was presented by Dr. Johann de Bono of the Royal Marsden Hospital Institute of Cancer Research. The presentation took place on September 15, 2024, from 9:00 a.m. to 5:00 p.m. CEST.

Vobra duo is an ADC targeting B7-H3, an antigen widely expressed in multiple solid tumors and part of the B7 family involved in immune regulation. The TAMARACK study specifically involved mCRPC patients who had received one prior androgen receptor axis-targeted therapy (ARAT) and potentially one taxane-containing regimen, but no other chemotherapy agents. It evaluates vobra duo at doses of 2.0 mg/kg and 2.7 mg/kg administered every four weeks.

MacroGenics is a biopharmaceutical enterprise dedicated to the discovery, development, manufacturing, and commercialization of innovative antibody-based therapeutics for cancer treatment. The company leverages its proprietary next-generation antibody technology platforms to create a robust pipeline of product candidates. MacroGenics’ expertise in protein engineering has enabled it to enter several strategic collaborations with global pharmaceutical and biotech companies.