Summary

The purpose of this Phase 2 study is to evaluate the clinical efficacy and safety of
Loncastuximab Tesirine (ADCT-402) in patients with relapsed or refractory Diffuse Large
B-Cell Lymphoma.

Objectives

This is a Phase 2, multi-center, open-label, single-arm study of the efficacy and safety of
loncastuximab tesirine used as monotherapy in patients with relapsed or refractory DLBCL. The
study will enroll approximately 140 patients

Loncastuximab Tesirine is an antibody drug conjugate (ADC) composed of a humanized antibody
directed against human cluster of differentiation 19 (CD19), stochastically conjugated
through a cathepsin-cleavable linker to SG3199, a pyrrolobenzodiazepine (PBD) dimer
cytotoxin. Loncastuximab tesirine has been designed to target and kill CD19-expressing
malignant B-cells.

A 2-stage design will be used in this clinical study, with an interim analysis for futility
on the first 52 patients. If =10 patients respond (CR+PR), the study will proceed to complete
full enrollment. Enrollment will continue during the interim analysis; however, further
enrollment will be halted if futility is confirmed.

For each patient, the study will include a Screening Period (of up to 28 days), a Treatment
Period (cycles of 3 weeks), and a Follow-up Period (approximately every 12 week visits for up
to 3 years after treatment discontinuation).

Patients may continue treatment until disease progression, unacceptable toxicity, or other
discontinuation criteria, whichever occurs first.