Purpose: For patients with refractory/relapsed Hodgkin lymphoma (roughly 20% of total cases), few effective therapeutic options exist. Currently, brentuximab vedotin (BV), a drug-conjugated anti-CD30 antibody, is one of the most effective approved therapy agents for these patients. However, many patients do not achieve complete remission and ultimately develop BV-resistant disease, necessitating a more detailed understanding of the molecular circuitry that drives BV sensitivity and the mechanism of BV resistance.
Experimental design: Here, we established a ubiquitin regulator-focused CRISPR library screening platform in Hodgkin lymphoma and carried out a drug sensitization screen against BV to identify genes regulating BV treatment sensitivity.
Results: Our CRISPR library screens revealed the ubiquitin-editing enzymes A20 and RBX1 as key molecule effectors that regulate BV sensitivity in Hodgkin lymphoma line L428. A20 negatively regulates NF-κB activity which is required to prevent BV cytotoxicity. In line with these results, the RNA-seq analysis of the BV-resistant single-cell clones demonstrated a consistent upregulation of NF-κB signature genes, as well as the ABC transporter gene ABCB1. Mechanically, NF-κB regulates BV treatment sensitivity through mediating ABCB1 expression. Targeting NF-κB activity synergized well with BV in killing Hodgkin lymphoma cell lines, augmented BV sensitivity, and overcame BV resistance in vitro and in Hodgkin lymphoma xenograft mouse models.
Conclusions: Our identification of this previously unrecognized mechanism provides novel knowledge of possible BV responsiveness and resistance mechanisms in Hodgkin lymphoma, as well as leads to promising hypotheses for the development of therapeutic strategies to overcome BV resistance in this disease.
©2020 American Association for Cancer Research.