Study to Evaluate the Efficacy and Safety of Loncastuximab Tesirine in Patients With Relapsed or Refractory Diffuse Large B-Cell Lymphoma

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 via a
valine-alanine cleavable, maleimide linker to 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.

Inclusion Criteria:

- Male or female patient aged 18 years or older.

- Pathologic diagnosis of DLBCL, as defined by the 2016 WHO classification, to include:
DLBCL not otherwise specified; primary mediastinal large B-cell lymphoma; and
high-grade B-cell lymphoma, with MYC and BCL2 and/or BCL6 rearrangements

- Relapsed or refractory disease following two or more multi-agent systemic treatment
regimens

- Patients who have received previous CD19-directed therapy must have a biopsy that
shows CD19 protein expression after completion of the CD19-directed therapy.

- Measurable disease as defined by the 2014 Lugano Classification

- Availability of formalin-fixed paraffin-embedded (FFPE) tumor tissue block or minimum
10 freshly cut unstained slides if block is not available

- ECOG performance status 0-2

- Adequate organ function

- Negative beta-human chorionic gonadotropin (β-HCG) pregnancy test within 7 days prior
to start of study drug (C1D1) for women of childbearing potential

- Women of childbearing potential must agree to use a highly effective method of
contraception from the time of giving informed consent until at least 16 weeks after
the last dose of loncastuximab tesirine. Men with female partners who are of
childbearing potential must agree that they will use a highly effective method of
contraception from the time of giving informed consent until at least 16 weeks after
the patient receives his last dose of loncastuximab tesirine.

Exclusion Criteria:

- Previous treatment with loncastuximab tesirine

- Known history of hypersensitivity to or positive serum human ADA to a CD19 antibody

- Pathologic diagnosis of Burkitt lymphoma

- Active second primary malignancy other than non-melanoma skin cancers, non-metastatic
prostate cancer, in situ cervical cancer, ductal or lobular carcinoma in situ of the
breast, or other malignancy that the Sponsor's medical monitor and Investigator agree
and document should not be exclusionary

- Autologous stem cell transplant (ASCT) within 30 days prior to start of study drug
(C1D1)

- Allogeneic stem cell transplant (AlloSCT) within 60 days prior to start of study drug
(C1D1)

- Active graft-versus-host disease

- Post-transplant lymphoproliferative disorders

- Active autoimmune disease, including motor neuropathy considered of autoimmune origin
and other central nervous system (CNS) autoimmune disease

- Known seropositive and requiring anti-viral therapy for human immunodeficiency (HIV)
virus, hepatitis B virus (HBV), or hepatitis C virus (HCV).

- History of Stevens-Johnson syndrome or toxic epidermal necrolysis

- Lymphoma with active CNS involvement at the time of screening, including
leptomeningeal disease

- Clinically significant third space fluid accumulation (i.e., ascites requiring
drainage or pleural effusion that is either requiring drainage or associated with
shortness of breath)

- Breastfeeding or pregnant

- Significant medical comorbidities

- Major surgery, radiotherapy, chemotherapy or other anti-neoplastic therapy within 14
days prior to start of study drug (C1D1), except shorter if approved by the Sponsor

- Use of any other experimental medication within 14 days prior to start of study drug
(C1D1)

- Planned live vaccine administration after starting study drug (C1D1)

- Failure to recover to Grade ≤1 (Common Terminology Criteria for Adverse Events version
4.0 [CTCAE v4.0]) from acute non-hematologic toxicity (Grade ≤2 neuropathy or
alopecia) due to previous therapy prior to screening

- Congenital long QT syndrome or a corrected QTcF interval of >480 ms at screening
(unless secondary to pacemaker or bundle branch block)

- Any other significant medical illness, abnormality, or condition that would, in the
Investigator's judgment, make the patient inappropriate for study participation or put
the patient at risk