TAHOE

Inclusion Criteria:

- Participant must have histologically or cytologically confirmed advanced or metastatic
Small Cell Lung Cancer (SCLC) with documented first disease progression during or
following front-line platinum-based systemic regimen

- Tumor must have high Delta-like protein 3 (DLL3) expression defined as having ≥ 75%
tumor cells staining positive according to the VENTANA DLL3 (SP347) IHC Assay.

- Participant must have measurable disease, as defined per Response Evaluation Criteria
in Solid Tumors (RECIST) version 1.1.

- Participant must have an Eastern Cooperative Oncology Group (ECOG) performance status
of 0 or 1.

- Participant must have recovery to Grade 0 or 1 of any clinically significant toxicity
(excluding alopecia) prior to initiation of study drug administration.

Exclusion Criteria:

- Participant has a documented history of a cerebral vascular event (stroke or transient
ischemic attack), unstable angina, myocardial infarction, or cardiac symptoms
consistent with New York Heart Association Class (NYHA) III - IV within 6 months prior
to their first dose of study drug.

- Participant has known leptomeningeal metastases.

- Participant has received more than one prior systemic therapy regimen for SCLC.

- Participant had a serious infection within 2 weeks prior to randomization, including
any Grade 3 or higher viral, bacterial, or fungal infection.

- Participant has a history of active malignancies other than SCLC within the past 2
years prior to study entry, with the exception of in situ cancer which was curatively
treated.

- Participant had prior exposure to topotecan, irinotecan or any other topoisomerase I
inhibitors.