Study in Patients With SCLC of Veliparib in Combination With Topotecan

Inclusion Criteria:

* Subject must be ≥ 18 years of age
* Subject with progressive or recurrent ED-SCLC after first line platinum-based therapy, which is either histologically or cytologically confirmed
* Performance status (PS) 0-2 ECOG
* Adequate bone marrow reserve
* Total bilirubin \< 2 x upper limit of normal
* AST and ALT \< 2.5 x upper limit of normal, or \< 5 x upper limit of normal in case of liver metastases
* Serum creatinine \< 2 x upper limit of normal or creatinine clearance \> 50 ml/min

Exclusion Criteria:

* Other anti-cancer chemotherapy or radiotherapy
* Symptomatic motor or sensory neuro-toxicities CTCAE \> Grade 2 or any other unresolved toxicities from prior systemic anti-cancer therapy or radiotherapy CTCAE \> Grade 1
* Known hypersensitivity to topotecan or veliparib
* Brain or meningeal metastasis (unless they are asymptomatic and not requiring systemic corticosteroid therapy)
* Major surgery within 6 weeks prior to first treatment on study (subjects must have completely recovered from any previous surgery prior to first treatment on study).
* History of cardiac events within the past 3 months
* Uncontrolled severe hypertension
* Abdominal or tracheo-oesophageal fistula, gastrointestinal perforation, or intra-abdominal abscess
* Uncontrolled nausea / vomiting / diarrhea
* Previous malignancy (other than SCLC) in the last 3 years, except basal cell cancer of the skin, pre-invasive cancer of the cervix, T1a prostate carcinoma or superficial bladder tumor \[Ta, Tis and T1\] that was cured in the opinion of the investigator.
* History of organ allograft
* Active (acute or chronic) or uncontrolled infection of bacterial, mycotic or viral genesis