Diffuse large B-cell lymphoma (DLBCL), the most common hematologic malignancy, is an aggressive form of non-Hodgkin lymphoma. Approximately 60% of DLBCL patients achieve long-term disease-free survival from frontline R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone), but patients with relapsed or refractory disease have poor prognosis. Doxorubicin (Dox) remains the most active anti-lymphoma agent, but its use is limited by well-characterized toxicities, including potentially irreversible cardiac damage. Targeted and specific delivery of Dox to tumors to overcome these limitations has been an area of active research. Targeted delivery of Dox via the transferrin receptor (TFR1) has preclinical efficacy in solid malignancies but has yet to be explored in lymphoma. We have uncovered for the first time a significant association between TFR1 expression and poor prognosis in DLBCL. Carbon-nitride dots (CNDs) are third-generation nanocarriers with inherent photoluminescence, which are easily conjugated with a wide variety of substrates. We conjugated Dox and transferrin (TF), the ligand for TFR1, to CNDs to develop CND-Dox-TF (CDT). CDT is uniquely designed to enhance Dox delivery to TFR1-expressing DLBCL tumors while limiting effects on nonmalignant tissues. BJAB and Farage cell lines treated with CDT for 24 hours underwent apoptosis at a significantly lower concentration when compared to Dox (50 nM vs. 1000 nM). Overall, CDT was 1-2 Log10 more potent than Dox against DLBCL cell lines. Co-incubation with 250 uM of antagonist holo-transferrin significantly decreased BJAB and Farage sensitivity to CDT, confirming activity through TFR1. Confocal microscopy of BJAB cells incubated up to 24 hours with 250 nM Dox and 30 nM CDT reveled enhanced nuclear colocalization of Dox at a significantly lower concentration. Prior dose-finding experiments in non-tumor bearing mice identified a CDT safe working dose of 33.0 mg/kg containing 16% moles of Dox in comparison to Dox maximum-tolerated dose (MTD) 3.3 mg/kg. We engrafted 2 groups of 10 NSG mice with a Dox-sensitive high-TFR1 expressing patient-derived xenograft (PDX) tumor. Mice were dosed with CDT and Dox on day 0, 14, and 24. CDT demonstrated similar anti-lymphoma efficacy with reduced toxicity: CDT-treated mice displayed no significant decline in body weight, which is characteristic and was observed following each single-agent Dox treatment. Histology analyses revealed little to no obvious damage to CDT-treated nonmalignant tissues, including myocardium. With a working dose of CDT identified, we now have under way clinically relevant R-CHOP vs. R-nanoCHOP (CDT substituted for Dox) assessments in our PDX mouse model. Capitalizing on the unique design, we expect to observe improved anti-lymphoma efficacy, with decreased toxicities and an improvement in overall survival. In sum, we provide mechanistic insight for novel DLBCL nano-chemotherapy and illustrate preclinical efficacy for a promising new therapeutic approach.
Citation Format: Artavazd Arumov, Piumi Y. Liyanage, Asaad Trabolsi, Evan R. Roberts, Braulio Ferreira, Daniel Bilbao, Roger M. LeBlanc, Jonathan H. Schatz. Cytotoxic mechanism of a novel transferrin receptor-targeting chemotherapeutic nanocarrier for use in diffuse large B-cell lymphoma [abstract]. In: Proceedings of the AACR Virtual Meeting: Advances in Malignant Lymphoma; 2020 Aug 17-19. Philadelphia (PA): AACR; Blood Cancer Discov 2020;1(3_Suppl):Abstract nr PO-48.