Inclusion criteria for dose escalation: solid tumor patients (≥1 prior systemic therapy) or lymphoma patients (≥2 prior therapies per 2016 WHO criteria) with ≥1 evaluable lesion (RECIST v1.1/Lugano 2014). Dose expansion includes MCL, DLBCL (both post-≥2 therapies including BTK inhibitors), and TNBC (post-≥2 therapies), all requiring measurable lesions. Additional requirements: life expectancy >3 months, ECOG 0/1, adequate organ function, tumor tissue/blood sample provision, negative pregnancy test (females), and contraception use by all participants.

The study will determine the Maximum Tolerated Dose (MTD) of CS5001 during dose escalation (over ~6 months) based on dose-limiting toxicities (DLTs) observed in participants receiving triweekly injections. The Recommended Phase 2 Dose (RP2D) will be derived from MTD data or a lower tolerable dose, incorporating safety, pharmacokinetic, pharmacodynamic, and efficacy profiles. Adverse events will be monitored for severity and incidence until 90 days post-treatment or new anticancer therapy initiation.

Eligible participants (≥18 years) include: Part 1 - B-cell NHL patients (excluding specific subtypes) with optional CD19 confirmation; Part 2 - confirmed CD19+ B-cell NHL (DLBCL, FL, MCL, etc.) requiring biopsy for complete response verification. All patients must have relapsed/refractory disease (≥2 prior therapies), ECOG 0-1, life expectancy ≥10 weeks, and meet contraception requirements. Part 1 allows non-measurable disease with optional biopsy; Part 2 requires measurable disease (Lugano criteria) and mandatory biopsy.

Immunogenicity of IKS03 (Parts 1-2) will be evaluated through ADA measurements in serum (up to 42 months). Pharmacokinetic analysis will characterize IKS03 plasma concentrations throughout the study period. The recommended Phase 2 dose (RP2D) will be determined based on antitumor activity, tolerability, and target plasma concentration achievement (up to 42 months).