ROR1 and B-cell chronic lymphocytic leukemia: Interestingly, the anti-ROR1 antibody-drug conjugate zilovertamab vedotin (VLS-101) has shown a strong activity in xenograft models of CLL transformed into Richter syndrome (RS) (54), thus providing the basis for the currently ongoing phase 1 clinical trial investigating VLS-101 safety and efficacy in patients with hematologic malignancies, including CLL (NCT03833180).