A phase 1 study evaluating safety and pharmacokinetics of losatuxizumab vedotin (ABBV-221), an anti-EGFR antibody-drug conjugate carrying monomethyl auristatin E, in patients with solid tumors likely to overexpress EGFR.

Losatuxizumab vedotin (formerly ABBV-221) is a second-generation antibody-drug conjugate targeting epidermal growth factor receptor (EGFR). In this multicenter phase 1 study, eligible patients with EGFR-dependent solid tumors received losatuxizumab vedotin (3 + 3 design) intravenously at starting dose of 0.3 mg/kg over 3 h per 21-day cycle, with alternate dosing schedules utilized (2 weeks on/1 week off or weekly) to mitigate infusion reactions. Forty-five patients received ≥1 doses of losatuxizumab vedotin (13 colon, 6 non-small cell lung cancer, 5 head and neck [HNC], 5 glioblastoma multiforme, 2 breast, 14 other). Tumor samples were evaluated for EGFR protein expression by immunohistochemistry, EGFR and EGFR ligand mRNA expression by RNAseq, and results compared with outcome. Most common adverse events were infusion-related reaction (22/45; 49%) and fatigue (20/45; 44%). While most infusion reactions were grade ≤ 2, four patients experienced grade ≥3 infusion reactions. Several infusion reaction mitigation strategies were explored. Because of the high incidence of infusion reactions, the trial was stopped and the maximum tolerated dose was not reached. The last cleared dose: 6 mg/kg/cycle. Nineteen patients (42%) had stable disease; 4 remained on study >6 months. One HNC patient with increased levels of EGFR and EGFR ligands (amphiregulin, epiregulin) achieved a confirmed partial response. Pharmacokinetic analysis of losatuxizumab vedotin showed exposures appeared to be approximately dose-proportional. The high frequency of infusion reactions necessitated early closure of this trial. The detailed mitigation strategies used in this protocol for infusion-related reactions may provide beneficial information for trial design of agents with high infusion reaction rates.

Safety, efficacy, and pharmacokinetics of navitoclax (ABT-263) in combination with irinotecan: results of an open-label, phase 1 study.

PURPOSE: The oral Bcl-2 inhibitor navitoclax demonstrated activity in solid and hematologic malignancies as monotherapy and in combination with other cytotoxic agents in preclinical and early clinical studies. We evaluated the safety, pharmacokinetics (PK), and antitumor activity of navitoclax plus irinotecan. METHODS: In this multicenter, open-label, phase 1 dose escalation study, adults with advanced solid tumors received navitoclax (starting dose 150 mg/day) in combination with 1 of 2 irinotecan schedules during a 21-day cycle: a once-every-3-week regimen (Q3W 180, 250, or 350 mg/m(2)) or a once-weekly regimen (QW 75 or 100 mg/m(2)). Enrollment occurred until a maximum tolerated dose (MTD) and/or recommended phase 2 dose (RPTD) was reached. RESULTS: All patients (Q3W, n = 14; QW, n = 17) were evaluable for safety, PK, and efficacy. The most common adverse event in both groups was diarrhea (Q3W 92.9 %; QW 76.5 %), which was the most frequent grade 3/grade 4 adverse event (Q3W 42.9 %; QW 29.4 %). The study was amended to exclude 4 UGT1A1*28 7/7 homozygous patients due to frequent irinotecan-related grade 3/grade 4 diarrhea and/or febrile neutropenia. No apparent PK interactions between navitoclax and irinotecan were observed. The MTD of the combination was exceeded in the Q3W group at the lowest dose administered. In the QW group, the MTD and RPTD for navitoclax were 150 mg when combined with irinotecan 75 mg/m(2). One patient in each group achieved a partial response. CONCLUSION: The RPTD of navitoclax in combination with irinotecan 75 mg/m(2) QW during a 21-day cycle was 150 mg in these heavily pretreated patients.

Safety, efficacy, and pharmacokinetics of navitoclax (ABT-263) in combination with erlotinib in patients with advanced solid tumors.

PURPOSE: Navitoclax (ABT-263), a novel, oral Bcl-2 inhibitor, enhances the antitumor effects of chemotherapy in vitro by lowering the apoptotic threshold. This phase I study (NCT01009073) evaluated the safety, pharmacokinetics, and preliminary antitumor activity of navitoclax combined with erlotinib in patients with advanced solid tumors. PATIENTS AND METHODS: An open-label dose escalation study included an arm evaluating navitoclax combined with erlotinib, which included a dose escalation cohort and a planned safety expansion cohort. Patients with documented cancers for whom erlotinib therapy was appropriate received erlotinib 150 mg orally once daily plus navitoclax 150 mg orally once daily, with navitoclax dose escalation via a continuous reassessment method model. RESULTS: Eleven patients were enrolled, including six patients with nonsmall cell lung cancer. Dose-limiting toxicities, most commonly diarrhea, were observed in 4 patients. Navitoclax dosing remained at 150 mg/day because the maximum tolerated dose was exceeded at this starting dose. The planned dose escalation did not occur; no recommended phase II dose (RPTD) was identified, and there was no safety expansion cohort. The most common treatment-related adverse events were diarrhea, nausea, vomiting, and decreased appetite. Pharmacokinetic analysis showed no apparent interactions between co-administered navitoclax and erlotinib. No objective responses were observed; the disease control rate was 27 % (95 % CI, 6-61 %). CONCLUSION: At the erlotinib and navitoclax doses administered, RPTD was not reached, but the safety profile of the combination was consistent with data from monotherapy studies. There were no apparent pharmacokinetic interactions between erlotinib and navitoclax. Three patients had stable disease.