Investigation of GSK2879552 in Subjects With Relapsed/Refractory Small Cell Lung Carcinoma

Inclusion Criteria:

* Provided signed written informed consent
* Males and females \>=18 years of age (at the time consent is obtained).
* Histologically or cytologically confirmed diagnosis of small cell lung carcinoma. Subjects must have measurable disease per RECIST 1.1 (for Part 2 only).
* Recurrent or refractory disease after receiving at least one prior standard/approved platinum-containing chemotherapy regimen, or where standard therapy is refused. Part 2 only: Subjects must have recurrent disease after receiving a maximum of two prior chemotherapy regimens including at least one platinum containing regimen.
* Eastern Cooperative Oncology Group (ECOG) performance status of \<= 1. (ECOG performance status of 0 or 1).
* Tumor tissue requirements: Availability of archival tissue, or willingness to undergo fresh biopsy at baseline; Enrollment in PK/PD cohort may be limited to subjects with disease amenable to pre- and post-dose biopsies, and willingness to undergo biopsy.
* All prior treatment-related toxicities must be National Cancer Institute- Common Toxicity Criteria for Adverse Events (NCI-CTCAE), version 4.0 \<=Grade 1 at the time of enrollment (except for alopecia)
* Adequate baseline organ function
* Women of childbearing potential must have a negative serum pregnancy test within 7 days of first dose of study treatment and agree to use effective contraception, as defined in protocol, during the study and for 7 days following the last dose of study treatment.
* Men with a female partner of childbearing potential must have either had a prior vasectomy or agree to use effective contraception as described in protocol from the administration of the first dose of study treatment until 3 months after the last dose of study treatment to allow for clearance of any altered sperm.
* Able to swallow and retain orally administered study treatment and does not have any clinically significant gastrointestinal (GI) abnormalities that may alter absorption such as malabsorption syndrome or major resection of the stomach and/or bowels.
* French subjects: In France, a subject will be eligible for inclusion in this study only if either affiliated to or a beneficiary of a social security category.

Exclusion Criteria:

* Concurrent malignancy other than SCLC. History of other malignancy is allowed as long as there is no evidence of active disease or need for treatment.
* Currently receiving anti-cancer therapy. Exceptions: Zoledronic acid and denosumab to treat bone metastasis are allowed.
* Prior treatment with temozolomide, dacarbazine or procarbazine.
* Prior treatment with poly ADP ribose polymerase (PARP) inhibitors (e.g., olaparib, ABT-888).
* Baseline Montreal Cognitive Assessment (MOCA) score of 22 or lower.
* Received major surgery, radiotherapy, or immunotherapy within 4 weeks of GSK2879552 administration. Chemotherapy regimens with delayed toxicity within the last four weeks (six weeks for prior nitrosourea or mitomycin C). Chemotherapy regimens given continuously or on a weekly basis with limited potential for delayed toxicity or palliative radiation to a limited area within the last two weeks.
* Administration of an investigational drug within 28 days or 5 half-lives, whichever is shorter preceding the first dose of study treatment(s) in this study.
* French subjects: The French subject has participated in any study using an investigational study treatment(s) during the previous 28 days.
* Subjects with current/a history of bleeding disorder or coagulopathy or who are at particularly high risk for bleeding complications.
* Requiring anticoagulants at therapeutic doses or platelet inhibitor.
* Current use of a prohibited medication or expected to require any of these medications during treatment with the investigational drug
* Evidence of severe or uncontrolled systemic diseases. Any serious and/or unstable pre-existing medical, psychiatric disorder, or other conditions that could interfere with subject's safety, obtaining informed consent or compliance to the study procedures, in the opinion of the investigator
* Known active Human Immunodeficiency Virus (HIV), Hepatitis B Virus (HBV) or Hepatitis C Virus (HCV) infections. Subjects with laboratory evidence of HBV clearance may be enrolled
* Leptomeningeal metastases or spinal cord compression due to disease.
* Subjects with previously untreated or uncontrolled brain metastases.
* Cardiac abnormalities
* Have a known immediate or delayed hypersensitivity reaction or idiosyncrasy to drugs chemically related to GSK2879552 or LSD1 inhibitors that contraindicates their participation.
* Lactating female
* Consumption of Seville oranges, grapefruit, grapefruit hybrids, grapefruit juice, pommelos, or exotic citrus fruits, from 1 day prior to the first dose of study treatment(s) until the last dose of study drug.