Study to Evaluate the Efficacy and Safety of Camidanlumab Tesirine (ADCT-301) in Patients With Relapsed or Refractory Hodgkin Lymphoma

Inclusion Criteria:

   1. Written informed consent must be obtained prior to any procedures.

   2. Male or female participant aged 18 years or older. (16 years or older at US based
   sites)

   3. Pathologic diagnosis of classical Hodgkin lymphoma (cHL).

   4. Patients with relapsed or refractory cHL, who have received at least 3 prior lines of
   systemic therapy (or at least 2 prior lines in HSCT ineligible patients) including
   brentuximab vedotin and a checkpoint inhibitor approved for cHL (e.g., nivolumab or
   pembrolizumab). Note 1: Receipt of HSCT to be included in the number of prior
   therapies needed to meet eligibility.

   5. Measurable disease as defined by the 2014 Lugano Classification.

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

   Note 1: Any biopsy since initial diagnosis is acceptable, but if several samples are
   available, the most recent sample is preferred.

   Note 2: If a sufficient amount of tissue is not available, a fresh biopsy may be
   taken, provided the procedure is not deemed high-risk and is clinically feasible, and
   provided it is approved locally.

   7. Eastern Cooperative Oncology Group (ECOG) performance status 0-2.

   8. Adequate organ function as defined by Screening laboratory values within the following
   parameters:

      1. Absolute neutrophil count (ANC) ≥ 1.0 × 103/μL (off growth factors at least 72
      h).

      2. Platelet count ≥ 75 × 103/μL without transfusion in the past 2 weeks.

      3. ALT, AST, or GGT ≤ 2.5 × the upper limit of normal (ULN) if there is no liver
      involvement; ALT or AST ≤ 5 × ULN if there is liver involvement.

      4. Total bilirubin ≤ 1.5 × ULN (participants with known Gilbert's syndrome may have
      a total bilirubin up to ≤ 3 × ULN with direct bilirubin ≤ 1.5 × ULN).

      5. Blood creatinine ≤ 3.0 × ULN or calculated creatinine clearance ≥ 30 mL/min by
      the Cockcroft-Gault equation.

   Note: A laboratory assessment may be repeated a maximum of two times during the
   Screening Period to confirm eligibility.

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

10. Women of childbearing potential (WOCBP) must agree to use a highly effective method of
   contraception from the time of giving informed consent until at least 9.5 months after
   the last dose of Camidanlumab Tesirine. Men with female partners who are of
   childbearing potential must agree to use a highly effective method of contraception
   from the time of giving informed consent until at least 6.5 months after the
   participants receives his last dose of Camidanlumab Tesirine.

Exclusion Criteria:

   1. Previous treatment with Camidanlumab Tesirine.

   2. Participation in another investigational interventional study. Being in follow-up of
   another investigational study is allowed.

   3. Known history of hypersensitivity to or positive serum human anti-drug antibody (ADA)
   to a CD25 antibody.

   4. Allogenic or autologous transplant within 60 days prior to start of study drug.

   5. Active graft-versus-host disease (GVHD), except for non-neurologic symptoms as a
   manifestation of mild (≤ Grade 1) chronic GVHD.

   6. Post-transplantation lymphoproliferative disorders.

   7. 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.

   8. History of symptomatic autoimmune disease (e.g., rheumatoid arthritis, systemic
   progressive sclerosis [scleroderma], systemic lupus erythematosus, Sjögren's syndrome,
   autoimmune vasculitis [e.g., Wegener's granulomatosis]) (subjects with vitiligo, type
   1 diabetes mellitus, residual hypothyroidism, hypophysitis due to autoimmune condition
   only requiring hormone replacement may be enrolled).

   9. History of neuropathy considered of autoimmune origin (e.g., polyradiculopathy
   including Guillain-Barré syndrome and myasthenia gravis) or other central nervous
   system autoimmune disease (e.g., poliomyelitis, multiple sclerosis).

10. History of recent infection (within 4 weeks of Cycle 1, Day 1 [C1D1]) considered to be
   caused by one of the following pathogens: HSV1, HSV2, VZV, EBV, CMV, measles,
   Influenza A, Zika virus, Chikungunya virus, mycoplasma pneumonia, Campylobacter
   jejuni, or enterovirus D68, or severe acute respiratory syndrome coronavirus 2
   (SARS-CoV-2).

   Note: An influenza test and a pathogendirected SARS CoV-2 test (such as polymerase
   chain reaction) are mandatory and must be negative before initiating study treatment
   (tests to be performed 3 days or less prior to dosing on C1D1; an additional 2 days
   are allowed in the event of logistical issues for receiving the results on time).

11. Participants known to be or having been infected with human immunodeficiency (HIV)
   virus, hepatitis B virus (HBV), or hepatitis C virus (HCV), and require anti-viral
   therapy or prophylaxis. Note: Serology testing is mandatory for patients with unknown
   status.

12. History of Stevens-Johnson syndrome or toxic epidermal necrolysis.

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

14. Hodgkin lymphoma (HL) with central nervous system involvement, including
   leptomeningeal disease.

15. 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).

16. Breastfeeding or pregnant.

17. Significant medical comorbidities, including uncontrolled hypertension (blood pressure
   [BP] ≥ 160/100 mmHg repeatedly), unstable angina, congestive heart failure (greater
   than New York Heart Association class II), electrocardiographic evidence of acute
   ischemia, coronary angioplasty or myocardial infarction within 3 months prior to
   screening, severe uncontrolled atrial or ventricular cardiac arrhythmia, poorly
   controlled diabetes, or severe chronic pulmonary disease.

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

19. Use of any other experimental medication within 30 days prior to start of study drug.

20. Any live vaccine within 4 weeks prior to start of study drug and planned live vaccine
   administration after starting study drug.

21. Congenital long QT (measure between Q wave and T wave in the electrocardiogram)
   syndrome, or a corrected QTc interval of ≥ 480 ms, at screening (unless secondary to
   pacemaker or bundle branch block).

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