A phase Ib/II study of HER3-targeting lumretuzumab in combination with carboplatin and paclitaxel as first-line treatment in patients with advanced or metastatic squamous non-small cell lung cancer

Purpose

This study investigated the safety and clinical activity of lumretuzumab, a humanised antihuman epidermal growth factor receptor 3 (HER3) monoclonal antibody, in combination with carboplatin and paclitaxel in first-line treatment of patients with squamous non-small cell lung cancer (sqNSCLC). HER3 ligand heregulin and HER3 protein expression were evaluated as potential biomarkers of clinical activity.

Patients and methods

This open-label, phase Ib/II study enrolled patients receiving lumretuzumab at 800 mg (flat) in combination with carboplatin (area under the curve (AUC) 6 mg/mL×min) and paclitaxel (200 mg/m²) administered intravenously on a every 3-week schedule. Adverse event (AE) rates and tumour responses were determined. Heregulin messenger RNA (mRNA) and HER3 protein expression were investigated in archival tumour biopsies.

Results

Altogether, 12 patients received lumretuzumab in combination with carboplatin and paclitaxel. The most frequent AEs were gastrointestinal, haematological and nervous system toxicities, which were generally mild and manageable. Partial responses were observed in 3 of 12 patients lasting 81, 177 and 207 days. All responses were achieved in tumours expressing higher heregulin mRNA levels.

Conclusion

Lumretuzumab in combination with carboplatin and paclitaxel was well tolerated. Objective responses were enriched in tumours expressing higher heregulin mRNA levels.

First-in-Human Phase I Study of Lumretuzumab, a Glycoengineered Humanized Anti-HER3 Monoclonal Antibody, in Patients with Metastatic or Advanced HER3-Positive Solid Tumors

PURPOSE

A first-in-human phase I study was conducted to characterize safety, efficacy, and pharmacokinetic (PK) and pharmacodynamic (PD) properties of lumretuzumab, a humanized and glycoengineered anti-HER3 monoclonal antibody, in patients with advanced cancer.

EXPERIMENTAL DESIGN

Twenty-five patients with histologically confirmed HER3-expressing tumors received lumretuzumab (100, 200, 400, 800, 1,600, and 2,000 mg) every two weeks (q2w) in 3+3 dose-escalation phase. In addition, 22 patients were enrolled into an extension cohort at 2,000 mg q2w.

RESULTS

There were no dose-limiting toxicities. Common adverse events (any grade) included diarrhea (22 patients, 46.8%), fatigue (21 patients, 44.7%), decreased appetite (15 patients, 31.9%), infusion-related reactions (13 patients, 27.7%), and constipation (10 patients, 21.3%). The peak concentration (Cmax) and area under the concentration-time curve up to the last measurable concentration (AUClast) of lumretuzumab increased more than dose proportionally from 100 mg up to 400 mg. Linear PK was observed with doses ≥ 400 mg q2w indicating target-mediated drug disposition saturation. Downregulation of HER3 membranous protein was observed in on-treatment tumor biopsies from 200 mg, and was maximal at and above 400 mg. An ex vivo assay demonstrated increased activation potential of peripheral NK lymphocytes with lumretuzumab compared with a non-glycoengineered anti-HER3 antibody. Ten patients (21.3%) had stable disease and remained on study at a median of 111 days (range, 80-225 days).

CONCLUSIONS

Lumretuzumab was well tolerated and showed evidence of clinical activity. Linear serum PK properties and plateauing of PD effects in serial tumor biopsies indicate optimal biologically active doses of lumretuzumab from 400 mg onwards.