MGC018 in Patients With Relapsed or Refractory Extensive-Stage Small-Cell Lung Cancer

Inclusion Criteria:

1. Age greater than or equal to 18 years at time of signing Informed consent form (ICF)

2. Ability to comply with the study protocol, in the investigator's judgment.

3. Histologically or cytologically confirmed advanced small cell lung cancer that isnot amenable to definitive therapy. Patients with epidermal growth factor receptor (EGFR)-mutant Non Small Cell Lung Cancer (NSCLC) that has transformed to Small CellLung Cancer (SCLC) will be allowed if their SCLC has progressed following treatmentwith platinum-based chemotherapy.

4. Disease progression during or following treatment with platinum-based chemotherapy. a) Patients could have received any number of therapies for relapsed or progressivedisease.

5. Measurable disease per RECIST v1.1

6. Eastern Cooperative Oncology Group (ECOG) Performance Status of 0-2

7. Adequate hematologic and end-organ function, defined by the following laboratorytest results, obtained within 14 days prior to initiation of study treatment:

8. Absolute Neutrophil Count (ANC) greater than or equal to (>/=) 1.0 x 10^9/L (1000/uL) without granulocyte colony-stimulating factor support

9. Platelet count >/=100 x 10^9/L (100,000/uL) without transfusion

10. Hemoglobin >/= 80 g/L (8 g/dL) (1) Patients may be transfused to meet thiscriterion.

11. Aspartate Aminotransferase (AST), Alanine Transaminase (ALT), and alkalinephosphatase (ALP) less than or equal to (</=) 2.5 x upper limit of normal (ULN), with the following exceptions:

12. Patients with documented liver metastases: AST and ALT </= 5 x ULN

13. Patients with documented liver or bone metastases: ALP </= 5 x ULN

14. Serum bilirubin </= 1.5 x ULN with the following exception: (1) Patients with known Gilbert disease: serum bilirubin </= 3 x ULN

15. Creatinine clearance >/= 30 mL/min (calculated using the Cockcroft-Gaultformula)

16. For patients not receiving therapeutic anticoagulation: internationalnormalized ratio (INR) and Partial Thromboplastin Time, Activated (aPTT) </= 1.5 x ULN

17. Ability to understand and the willingness to sign a written informed consentdocument.

18. Availability of pre-treatment tumor tissue via a fresh biopsy. If biopsy is notconsidered safe and medically feasible by the Investigator, the patient may beapproved for enrollment after consultation with the Principal Investigator.

19. For women of childbearing potential: agreement to remain abstinent (refrain fromheterosexual intercourse) or use contraceptive methods, and agreement to refrainfrom donating eggs, as defined below:

20. Women must remain abstinent or use contraceptive methods with a failure rate ofless than (<) 1% per year during the treatment period and for 6 months afterthe final dose of study treatment. Women must refrain from donating eggs duringthis same period.

21. A woman is considered to be of childbearing potential if she is postmenarchal,has not reached a postmenopausal state ( >/= 12 continuous months of amenorrheawith no identified cause other than menopause), and has not undergone surgicalsterilization (removal of ovaries and/or uterus). The definition ofchildbearing potential may be adapted for alignment with local guidelines orrequirements.

22. Examples of contraceptive methods with a failure rate of < 1% per year includebilateral tubal ligation, male sterilization, hormonal contraceptives thatinhibit ovulation, hormone-releasing intrauterine devices, and copperintrauterine devices.

23. The reliability of sexual abstinence should be evaluated in relation to theduration of the clinical trial and the preferred and usual lifestyle of thepatient. Periodic abstinence (e.g., calendar, ovulation, symptothermal, orpostovulation methods) and withdrawal are not adequate methods ofcontraception.

24. For men: agreement to remain abstinent (refrain from heterosexual intercourse) oruse contraceptive measures, and agreement to refrain from donating sperm, as definedbelow:

25. With a female partner of childbearing potential who is not pregnant, men whoare not surgically sterile must remain abstinent or use a condom plus anadditional contraceptive method that together result in a failure rate of < 1%per year during the treatment period and for 90 days after the final dose ofMGC018. Men must refrain from donating sperm during this this same period.

26. With a pregnant female partner, men must remain abstinent or use a condomduring the treatment period and 90 days after the final dose of MGC018 to avoidpotential exposure to the embryo.

27. The reliability of sexual abstinence should be evaluated in relation to theduration of the clinical trial and the preferred and usual lifestyle of thepatient. Periodic abstinence (e.g., calendar, ovulation, symptothermal, orpostovulation methods) and withdrawal are not adequate methods ofcontraception.

Exclusion Criteria:

1. Patients with treated brain metastases are eligible if they are symptomaticallystable while off steroid therapy for a minimum of 7 days

2. History of leptomeningeal disease

3. Patient who are receiving any other investigational agents

4. Major surgical procedure, other than for diagnosis, within 4 weeks prior toinitiation of study treatment, or anticipation of need for a major surgicalprocedure during the study

5. Diagnosis of another malignancy. However, patients with prior or concurrentmalignancy whose natural history or treatment does not have the potential tointerfere with the safety or efficacy assessment of the investigational regimen areeligible for this trial.

6. Evidence of pleural and/or pericardial effusion. A small and/or asymptomaticeffusion is not exclusionary.

7. Any other disease, metabolic dysfunction, physical examination finding, or clinicallaboratory finding that, in the view of the investigator, contraindicates the use ofan investigational drug, may affect the interpretation of the results, or may renderthe patient at high risk from treatment complications.

8. Pregnancy or breastfeeding, or intention of becoming pregnant during study treatmentor within 6 months after the final dose of study treatment.