A Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Preliminary Efficacy of YK012

This early-phase study is testing a new drug called STX-123 (or similar) in patients with relapsed or refractory B-cell non-Hodgkin lymphoma (B-NHL) — a group of blood cancers — to evaluate safety, dosing, and early signs of effectiveness. **You may be eligible if...** - You are age 18–65 with a confirmed diagnosis of relapsed or refractory B-NHL (including follicular lymphoma, DLBCL, mantle cell lymphoma, MALT lymphoma, Burkitt lymphoma, or others) - You have received prior treatment including rituximab and at least one second-line therapy - You have at least one measurable tumor on imaging - You are in good general health (ECOG ≤1) and have adequate blood, liver, and kidney function **You may NOT be eligible if...** - You have active central nervous system lymphoma - You have had a prior stem cell transplant (allogeneic) or CAR-T cell therapy in certain timeframes - You are pregnant or breastfeeding - You have significant ongoing side effects from prior treatment - You have active, uncontrolled infection including HIV or hepatitis B/C Talk to your doctor to see if this trial is right for you.