BH3 profiling
BH3 profiling revealed that at baseline, patients with B-cell ALL had more diversity in BCL-2 and BCL-XL dependency than did patients with T-cell ALL or early T-cell precursor ALL. The fact that responses were observed in patients who were BCL-2 or BCL-XL dependent, Dr. Rubnitz said, supports the use of venetoclax plus navitoclax in these patients. Analysis of these results led to a recommended phase 2 dose for pediatric patients of 400 mg venetoclax with 25 mg navitoclax (for patients weighing <45 kg) or 50 mg navitoclax (for patients weighing 45 kg or more).
Dr. Rubnitz concluded: “Venetoclax plus navitoclax plus chemotherapy was well tolerated in pediatric patients with relapsed/refractory ALL or LL, with promising response rates observed in a heavily pretreated pediatric population.”
Asked whether the combination might be used also before the refractory setting, in a minimal residual disease (MRD) setting, Dr. Rubnitz replied: “We have a lot of safety data on venetoclax but very little on navitoclax. The next trial, being developed by Seth Karol, MD, will include relapsed patients. MRD-positive patients will also be eligible for enrollment.” To a further question as to whether guiding titration via BH3 profiling would lead to improved outcomes, Dr. Rubnitz said, “I think BH3 profiling can be used to identify which patients will respond to these drugs, but we are still a long way from using it for titrating the doses and dose ratios for the two drugs.”
Dr. Rubnitz disclosed research funding from AbbVie.
SOURCE: Rubnitz JE et al. ASH 2020, Abstract 466.