Envafolimab (KN035), a novel PD-L1 antibody, demonstrated robust anti-tumour activity and was safe in patients with diverse advanced microsatellite instability-high/mismatch repair-deficient (MSI-H/dMMR) tumours, according to findings presented at the ESMO Asia Virtual Congress 2020, held 20 to 22 November 2020.
Jian Li of the Oncology, Peking University Cancer Hospital and Institute, China explained that envafolimab is a novel anti-PD-L1 single domain antibody formulated for subcutaneous (s.c.) injection. Professor Li and a research team evaluated the efficacy and safety of envafolimab in patients with advanced tumours in this single arm phase II study (NCT03667170).
The study enrolled 103 adults patients with previously treated MSI-H/dMMR advanced cancer in China, including 65 patients with colorectal cancer (CRC),18 with gastric cancer, and 20 patients with other tumour types. Eligible patients had failed ≥1 line of systemic treatment; specifically 41/65 patients with CRC who failed ≥ 2 lines of prior therapies including a fluoropyrimidine, oxaliplatin, or irinotecan, and 24 had failed one line of prior therapy with 2/3 of the same agents.
All patients were treated with envafolimab at 150 mg administered s.c. weekly until progression, unacceptable toxicity, or withdrawal.
The primary endpoint was the objective response rate (ORR) per RECIST v1.1 by blinded independent radiology review (BIRC).
Regarding the primary endpoint, with median follow-up of 11.5 months, patients in the overall population demonstrated a confirmed ORR per BIRC of 42.7% (95% confidence interval [CI] 33.0%-52.8%).
Per cancer type, the ORR was 43.1% (95% CI 30.8%-56.0%) in CRC; among the patients with CRC, the 24 patients failing one prior line of treatment showed a 62.5% ORR (95%CI 40.6%-81.2%) and the 41 patients who failed ≥2 prior lines demonstrated an ORR of 31.7% (95%CI 18.1%-48.1%). The 18 patients with gastric cancer showed an ORR of 44.4% (95%CI 21.5%-69.2%) and the ORR was 40.0% (95%CI19.1%-63.9%) in patients with other tumours.
The median progression-free survival per BIRC was 11.1 months in the overall population, 7.2 months in the CRC population, and not reached for patients in the gastric cancer or other tumours population.
Median overall survival (OS) and the median duration of response were not reached in any population. The 12-month OS rate was 74.6% in the overall population and the CRC, gastric cancer, and other tumours cohorts demonstrated 12-month OS of 72.9%, 83.3%, and 75.0%, respectively.
Similar results were found according to investigator assessment: the overall population had an ORR of 41.7%. Among patients with CRC, those failing 1 prior treatment had ORR 58.3% and those failing ≥2 prior lines had an ORR of 29.3%. Patients with gastric cncer demonstrated a 50% ORR and those with other tumours had a 40.0% ORR.
All grade treatment-related adverse events (TRAEs) occurred in 84.5% of the overall population and 15.5% of patients had grade 3-4 TRAEs. No grade 5 TRAE occurred.
The most common immune related AEs were hypothyroidism (15.5%) and hyperthyroidism (11.7%). No pneumonitis or colitis were reported. Local injection-site reactions grades 1-2 occurred in 8.7% of patients.
Based on presented findings, the investigators concluded that envafolimab demonstrated robust anti-tumour activity with a manageable safety profile in heavily pretreated patients with dMMR/MSI-H advanced cancers.
70MO – Shen L, Li J, Deng Y, et al. Efficacy and safety of envafolimab (KN035) in advanced tumors with mismatch-repair deficiency. ESMO Asia Virtual Congress 2020 (20-22 November 2020).