SNB-101 for Treatment of Extensive Stage Small Cell Lung Cancer

The purpose of the Phase 1 research is to test the safety, tolerability, maximum tolerated dose, and pharmacokinetics (PK- the study of how a medicine moves through subject body. It looks at how the drug is absorbed, travels in your blood, reaches different parts of subject body, and is eventually broken down and removed) of the SNB-101.The Phase 2 is to determine the optimal dose (amount of medicine that works best to treat a condition while causing the fewest side effects) of SNB-101 for further research and to collect a further information on PK, safety and tolerability. Once subject has completed assessments during screening and if subject is found eligible to participate in the study, study drug will be given by intravenous infusion on day 1 and day 15 of each cycle treatment. Throughout the treatment period, the study doctor will monitor subject for any changes to subject health. While subject is taking the study drug, we will ask subject the following: * How subject are feeling. * If subject has experienced any side effects. * If subject is taking other medications or if there are changes to the medications subject was taking before. The study drug will be taken over multiple cycles. A cycle is the time between the start of 1 round of treatment until the start of the next round. In this study, each treatment cycle is of 28 days.