Duration of Hematologic Improvement (HI)

Arm A (Platelets > 50,000 k/uL) LEN Initiation

Patients with baseline platelet counts \>50,000 k/uL received lenalidomide (LEN) PO daily or QOD on days 1-21. If platelet counts fell below 50,000 k/uL during treatment, patients discontinued LEN and received eltrombopag olamine (ELT) PO daily or QOD until platelet counts \> 50,000 k/uL were achieved, and then maintained for 2 weeks thereafter. If a platelet count \>50,000 k/uL was maintained, patients discontinued ELT and resumed only LEN as a single agent (PO daily or QOD). If platelets fell below 50,000 k/uL a second time, LEN was stopped and ELT was re-initiated at the dose last given to the patient. Once platelet counts were \>50,000 k/uL and maintained for 2 weeks, patients resumed LEN concurrently with ELT for all subsequent courses. Treatment repeated every 28 days for 4 courses in the absence of disease progression or unacceptable toxicity. Eltrombopag Olamine: Given PO Laboratory Biomarker Analysis: Correlative studies Lenalidomide: Given PO

Arm B (Platelets < 50,000 k/uL) ELT Initiation With Potential LEN Combination

Patients with baseline platelet counts \<50,000 k/uL received eltrombopag olamine (ELT) PO daily or QOD on days 1-28 until a platelet count \>50,000 k/uL was achieved. Once a platelet count\>50,000 k/uL was achieved the ELT dose was maintained for two weeks. After two weeks ELT was discontinued and LEN was started as in Arm A (i.e., eltrombopag olamine discontinued and lenalidomide started). Patients in Arm B were permitted to stay on ELT alone if a hematologic response on ELT was achieved as defined by the 2006 International Working Group (IWG) consensus criteria, or if baseline hemoglobin was \>10.0 g/dL and didn't decrease while on study drug. Treatment repeated every 28 days for 4 courses in the absence of disease progression or unacceptable toxicity. Eltrombopag Olamine: Given PO Laboratory Biomarker Analysis: Correlative studies Lenalidomide: Given PO

Arm C (Platelets < 50,000 k/uL) ELT Monotherapy

Patients in Arm B were permitted to stay on ELT alone if a hematologic response on ELT was achieved as defined by the 2006 International Working Group (IWG) consensus criteria, or if baseline hemoglobin was \>10.0 g/dL and didn't decrease while on study drug. Treatment repeated every 28 days for 4 courses in the absence of disease progression or unacceptable toxicity. Eltrombopag Olamine: Given PO Laboratory Biomarker Analysis: Correlative studies

Analysis denominator · Participants