A PHASE III, RANDOMIZED, OPEN-LABEL, MULTICENTER STUDY OF LURBINECTEDIN IN COMBINATION WITH ATEZOLIZUMAB COMPARED WITH ATEZOLIZUMAB AS MAINTENANCE THERAPY IN PARTICIPANTS WITH EXTENSIVE-STAGE SMALL-CELL LUNG CANCER (ES-SCLC) FOLLOWING FIRST-LINE INDUCTION THERAPY WITH CARBOPLATIN, ETOPOSIDE AND ATEZOLIZUMAB

Study GO43104 is a Phase III, randomized, open-label, multicenter study of lurbinectedin in
combination with atezolizumab compared with atezolizumab alone administered as maintenance
therapy in participants with extensive-stage small-cell lung cancer (ES-SCLC) after
first-line induction therapy with carboplatin, etoposide, and atezolizumab. The study
consists of 2 phases: an induction phase and a maintenance phase. Participants need to have
an ongoing response or stable disease per the Response Evaluation Criteria in Solid Tumor
(RECIST) v1.1 criteria after completion of 4 cycles of carboplatin, etoposide, and
atezolizumab induction treatment in order to be considered for eligibility screening for the
maintenance phase. Eligible participants will be randomized in a 1:1 ratio to receive either
lurbinectedin plus atezolizumab or atezolizumab in the maintenance phase.

Inclusion Criteria for the Induction Phase:

- ECOG PS of 0 or 1

- No prior systemic therapy for ES-SCLC

- Treatment-free for at least 6 months since last chemo/radiotherapy, among those
treated (with curative intent) with prior chemo/radiotherapy for limited-stage SCLC

- Histologically or cytologically confirmed ES-SCLC

- Adequate hematologic and end-organ function to receive 4 cycles of induction treatment
with carboplatin, etoposide and atezolizumab

- Measurable disease, as defined by RECIST v1.1

- Negative HIV test and no evidence of active Hepatitis B or Hepatitis C at screening

Exclusion Criteria for the Induction Phase:

- Presence or history of CNS metastases

- Active or history of autoimmune disease or deficiency

- History of malignancies other than SCLC within 5 years prior to enrollment

- Prior treatment with CD137 agonists or immune checkpoint blockade therapies, including
anti-CTLA-4, anti-PD-1, and anti-PD-L1 therapeutic antibodies, or lurbinectedin or
trabectedin

- History of idiopathic pulmonary fibrosis, organizing pneumonia, drug induced
pneumonitis, or idiopathic pneumonitis, or evidence of active pneumonitis on screening
chest computed tomography (CT) scan

- Treatment with investigational therapy within 28 days prior to enrollment

Inclusion Criteria for the Maintenance Phase:

- ECOG PS of 0 or 1

- Ongoing response or stable disease per RECIST 1.1 after 4 cycles of induction therapy

- Toxicities attributed to prior induction anti-cancer therapy or PCI resolved to Grade
<=1

- Adequate hematologic and end-organ function

Exclusion Criteria for the Maintenance Phase:

- Presence or history of CNS metastases

- Receiving consolidative chest radiation

- Severe infection within 2 weeks prior to randomization into the maintenance

- Treatment with therapeutic oral or IV antibiotics at the time of randomization