LB-100, Carboplatin, Etoposide, and Atezolizumab for the Treatment of Untreated Extensive-Stage Small Cell Lung Cancer

This phase Ib trial studies the side effects and best dose of LB-100 when given together with carboplatin, etoposide, and atezolizumab for the treatment of untreated extensive-stage small cell lung cancer. Drugs such as carboplatin and etoposide work in different ways to stop the growth of tumor cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Immunotherapy with monoclonal antibodies, such as atezolizumab, may help the body's immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. LB-100 has been shown to make anticancer drugs (chemotherapy) work better at killing cancer. LB-100 blocks a protein on the surface of cells called PP2A. Blocking this protein makes the tumor cells that express PP2A divide. This allows standard chemotherapy drugs such as carboplatin, etoposide, and atezolizumab work better at killing the tumor cells since these drugs work best at destroying cells that are dividing. Giving LB-100 in combination with standard chemotherapy drugs may work better to treat extensive-stage small cell lung cancer compared to standard chemotherapy drugs alone.

PRIMARY OBJECTIVE: I. To determine the recommended phase II dose (RP2D) of protein phosphatase 2A inhibitor LB-100 (LB-100) when given in combination with standard carboplatin/etoposide/atezolizumab in treatment naive patients with extensive-stage small cell lung cancer (ED-SCLC). SECONDARY OBJECTIVES: I. To assess objective response rate (ORR). II. To assess progression-free survival (PFS). III. To assess overall survival (OS). IV. To assess duration of overall response (DOR). V. To assess safety and adverse events (AEs). EXPLORATORY OBJECTIVES: I. The pharmacokinetics (PK) of LB-100 and etoposide. II. The biomarkers relevant to LB-100 and the disease state as well as their correlation to clinical outcomes. OUTLINE: This is a dose-escalation study of LB-100. INDUCTION: Patients receive LB-100 intravenously (IV) over 15 minutes on days 1 and 3, atezolizumab IV over 30-60 minutes on day 1, carboplatin IV over 30-60 minutes on day 1, and etoposide IV over 60 minutes on days 1-3. Treatment repeats every 21 days for 4 cycles in the absence of disease progression or unacceptable toxicity. MAINTENANCE: After completion of induction therapy, patients receive LB-100 IV over 15 minutes on days 1 and 3 and atezolizumab IV over 30 minutes on day 1. Cycles repeat every 21 days in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed for up to 30 days, and patients who discontinue study treatment without disease progression are followed every 6-8 weeks thereafter.