A Phase Ib Dose-Escalation Study of LCL161 Plus Oral Topotecan for Patients With Relapsed/Refractory Small Cell Lung Cancer and Select Gynecologic Malignancies.

BACKGROUND: This was an open-label, multicenter, single-arm phase Ib dose-escalation study of oral LCL161 administered in combination with oral topotecan in patients with relapsed/refractory small cell lung cancer (SCLC) and select gynecological cancers. METHODS: Cohorts of 3-6 patients initiated treatment with LCL161 and topotecan in escalating doses. LCL161 was administered orally on days 1, 8, and 15 of each 21-day cycle; topotecan was administered orally for the first 5 days of each 21-day cycle. RESULTS: A total of 35 patients were enrolled in 6 cohorts; 30 patients were female; 4 patients had SCLC and 19 patients had ovarian cancer. Median prior lines of therapy were 3 (1-10). Median duration of treatment was 7.1 weeks (0.1-174). The most frequent grade 3/4 treatment-related adverse events were thrombocytopenia (51.43%) and anemia (31.43%). ORR was 9.7%; 58% of patients had SD. The study was stopped early before the maximum tolerated dose (MTD) and recommended phase II dose (RP2D) were determined. CONCLUSION: The addition of LCL161 to oral topotecan caused more myelosuppression when dosed together than what was associated with either drug alone. Moreover, the drug combination did not improve outcomes. The study was terminated early (ClinicalTrials.gov Identifier: NCT02649673).

Clinical pharmacology of trastuzumab emtansine (T-DM1): an antibody-drug conjugate in development for the treatment of HER2-positive cancer.

PURPOSE: Trastuzumab emtansine (T-DM1) is an antibody-drug conjugate comprising trastuzumab and DM1, a microtubule polymerization inhibitor, covalently bound via a stable thioether linker. To characterize the pharmacokinetics (PK) of T-DM1 in patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer, data from four studies (TDM3569g, TDM4258g, TDM4374g, and TDM4688g) of single-agent T-DM1 administered at 3.6 mg/kg every 3 weeks (q3w) were assessed in aggregate. METHODS: Multiple analytes-T-DM1, total trastuzumab (TT), DM1, and key metabolites-were quantified using enzyme-linked immunosorbent assays or liquid chromatography tandem mass spectrometry. PK parameters of T-DM1, TT, and DM1 exposure were calculated using standard noncompartmental approaches and correlated to efficacy (objective response rate) and safety (platelet counts, hepatic transaminase concentrations). Immunogenicity was evaluated by measuring anti-therapeutic antibodies (ATA) to T-DM1 after repeated dosing using validated bridging antibody electrochemiluminescence or enzyme-linked immunosorbent assays. RESULTS: PK parameters for T-DM1, TT, and DM1 were consistent across studies at cycle 1 and steady state. T-DM1 PK was not affected by residual trastuzumab from prior therapy or circulating extracellular domain of HER2. No significant correlations were observed between T-DM1 exposure and efficacy, thrombocytopenia, or increased concentrations of transaminases. Across the studies, ATA formation was detected in 4.5% (13/286) of evaluable patients receiving T-DM1 q3w. CONCLUSIONS: The PK profile of single-agent T-DM1 (3.6 mg/kg q3w) is predictable, well characterized, and unaffected by circulating levels of HER2 extracellular domain or residual trastuzumab. T-DM1 exposure does not correlate with clinical responses or key adverse events.