Study of ADCT-301 in Patients With Selected Advanced Solid Tumors

This is a Phase 1b, multi-center, open-label study with a dose-escalation part and a dose
expansion part.

The duration of the study participation for each patient is defined as the time from the date
of signed written informed consent to the completion of the follow-up period, withdrawal of
consent, loss to follow-up, or death, whichever occurs first.

The study will include a Screening Period (of up to 28 days), a Treatment Period (with cycles
of 3 weeks for a Q3W dosing regimen), and a Follow-up Period (approximately every 12 week
visits) for up to 1 year after treatment discontinuation

Inclusion Criteria:

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

2. Male or female patient aged 18 years or older.

3. Pathologic diagnosis of solid tumor malignancy that is locally advanced or metastatic
at time of Screening:

Part 1 (Dose-Escalation):

Advanced solid tumors with literature evidence of CD25(+) Treg content, i.e., head and
neck, non-small cell lung cancer, gastric and esophageal cancers, pancreas, bladder,
renal cell carcinoma, melanoma, triple negative breast cancer, and ovarian cancers.

Part 2 (Dose-Expansion):

Advanced solid tumors literature evidence of CD25(+) Treg content:

- Group 1: One of the indications identified in Part 1, for which at least 1
response (PR or CR) was seen.

- Group 2: Any indication allowed in Part 1, except for the one selected for Group
1.

4. Patients who are refractory to or intolerant of existing therapy(ies) known to provide
clinical benefit for their condition.

5. Patients with advanced/metastatic cancer, with measurable disease as determined by
RECIST v1.1 or irRC/irRECIST/iRECIST.

6. Patient must have a site of disease amenable to biopsy and be willing to undergo fresh
biopsy procedures (minimum 3 passes each) prior to first dose, according to the
treating institution's guidelines.

7. ECOG performance status 0-1.

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

1. Absolute neutrophil count (ANC) ≥ 1.5 × 10^3/μL (off growth factors at least 72
h).

2. Platelet count ≥100 × 10^3/μL without transfusion in the past 10 days.

3. Hemoglobin ≥9 g/dL (5.6 mmol/L) (prior transfusion allowed).

4. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), or gamma
glutamyl transferase (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.

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

6. Blood creatinine ≤1.5 × ULN or calculated creatinine clearance ≥60 mL/min by the
Cockcroft-Gault equation.

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 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 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 16 weeks after the patient
receives his last dose of camidanlumab tesirine

Exclusion Criteria:

1. Participation in another investigational interventional study.

2. Prior therapy with a CD25 (IL-2R) antibody within the last 4 months.

3. Known history of ≥Grade 3 hypersensitivity to a therapeutic antibody.

4. Patients with prior solid organ or allogeneic bone marrow transplant.

5. 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
I diabetes mellitus, residual hypothyroidism, hypophysitis due to autoimmune condition
only requiring hormone replacement may be enrolled).

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

7. History of recent infection (within 4 weeks of C1D1) considered to be caused by one of
the following pathogens: herpes simplex virus 1/2 (HSV1, HSV2), varicella zoster
(VZV), Epstein-Barr virus (EBV), cytomegalovirus (CMV), measles, Influenza A, Zika
virus, Chikungunya virus, mycoplasma pneumonia, Campylobacter jejuni, or enterovirus
D68.

8. Known seropositive and requiring anti-viral therapy for human immunodeficiency (HIV)
virus, hepatitis B virus (HBV), or hepatitis C virus (HCV). Note: Testing is not
mandatory to be eligible but should be considered in patients with high risk for these
infections.

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

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

11. Symptomatic CNS metastases or evidence of leptomeningeal disease (brain MRI or
previously documented cerebrospinal fluid (CSF) cytology). Previously treated
asymptomatic CNS metastases are permitted provided that the last treatment (systemic
anticancer therapy and/or local radiotherapy) was completed ≥8 weeks prior to Day 1
except usage of low dose of steroids on a taper (i.e., up to 10 mg prednisone or
equivalent on Day 1 and consecutive days is permissible if being tapered down).
Patients with discrete dural metastases are eligible.

12. 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).

13. Active diarrhea CTCAE Grade 2 or a medical condition associated with chronic diarrhea
(such as irritable bowel syndrome, inflammatory bowel disease).

14. Active infection requiring systemic antibiotic therapy.

15. Active bleeding diathesis or significant anticoagulation (international normalized
ratio [INR] ≥2.0).

16. Breastfeeding or pregnant.

17. Significant medical comorbidities, including uncontrolled hypertension (blood pressure
[BP] ≥160 mmHg systolic and/or ≥110 mmHg diastolic repeatedly with or without anti
hypertensive medication), unstable angina, congestive heart failure (greater than New
York Heart Association class II), electrocardiographic evidence of acute ischemia,
coronary angioplasty or myocardial infarction within 6 months prior to screening,
severe uncontrolled atrial or ventricular cardiac arrhythmia, poorly controlled
diabetes, active ulceration of the upper gastrointestinal (GI) tract or GI bleeding,
or severe chronic pulmonary disease.

18. 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.
For cytotoxic agents that have major delayed toxicity, e.g., mitomycin C and
nitrosoureas, 4 weeks is indicated as washout period. For patients receiving systemic
anticancer immunotherapies (as opposed to intralesional) that lead to activation of
Teffs and/or increase the Teff/Treg ratio, such as anti-PD-1 antibodies, 5 half-lives
are indicated as the washout period.

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

20. Patients requiring concomitant immunosuppressive agents or chronic treatment with
corticosteroids except:

- replacement dose steroids in the setting of adrenal insufficiency

- topical, inhaled, nasal, and ophthalmic steroids are allowed

21. Planned live vaccine administration after starting study drug (C1D1).

22. Congenital long QT syndrome, or a corrected QTcF interval of ≥ 480 ms, at screening
(unless secondary to pacemaker or bundle branch block).

23. 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.

24. 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