This study is exploring a new treatment called OBI-3424 for patients with two types of blood cancer: T-cell acute lymphoblastic leukemia (T-ALL) and T-cell lymphoblastic lymphoma (T-LBL). These conditions occur when certain white blood cells grow uncontrollably. The study is in two phases to find the safest dose and see how well it works.

Patients will receive OBI-3424 through an IV (a needle in the vein) over 30 minutes on days 1 and 8 of a cycle. Each cycle lasts 21 days, and the treatment can go up to 17 cycles, unless the cancer worsens or side effects become too severe. The study also involves collecting blood and cerebrospinal fluid (CSF) samples and possibly taking a CT scan.

• The study may last up to 5 years with initial monthly checkups, gradually changing to every 6 months.
• No chemotherapy or new treatments 14 days before joining the study, and some medications need to be stopped temporarily.
• Patients must be at least 12 years old and meet medical criteria to participate.