The board of directors of Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. announced that at the American Association for Cancer Research (AACR) Annual Meeting 2024 to be held in San Diego, California, the United States of America from April 5 to 10, 2024, the Company will present updated efficacy and safety results for its anti-TROP2 ADC sacituzumab tirumotecan (sac-TMT) (formerly SKB264/MK-2870) in patients with previously treated advanced non-small cell lung cancer (NSCLC) from a phase 2 study in a poster session scheduled on April 9 2024, 1:30 PM - 5:00 PM local time (Abstract Presentation Number: CT247), and present preliminary efficacy and safety results for its anti-TROP2 ADC sac-TMT in patients with previously treated advanced gastric or gastroesophageal junction (GEJ) cancer from a phase 2 study in an oral presentation, which is scheduled in a session on April 9 2024, 2:30 PM - 4:30 PM local time (Abstract Presentation Number: CT038). The abstracts for the above studies were published on AACR's official website on April 5, 2024, local time. The study results are summarized as follows: Patients with previously treated advanced NSCLC were enrolled to receive sac-TMT at 5 mg/kg SECOND QUARTER OF W until disease progression or unacceptable toxicity (KL264-01, NCT04152499).

The data cut-off date was November 22, 2023. As of the Data Cut-off Date, 43 NSCLC patients had been enrolled and the median follow-up was 17.2 months. 21 patients with EGFR wild type had received a median of 3 prior regimens of therapy including anti-PD-1/L1 inhibitors.

22 patients with EGFR mutant had progressed on or after TKI therapy, 50% of whom also failed at least one line of chemotherapy. The most common Grade 3 treatment-related adverse events (TRAEs) were neutrophil count decreased (34.9%), anemia (30.2%), white blood cell (WBC) count decreased (25.6%), stomatitis (9.3%), and rash (7.0%). No TRAEs leading to treatment discontinuation or deaths occurred.

No drug-related interstitial lung disease (ILD)/pneumonitis was reported. Two Phase 3 global studies of sac-TMT in patients with 3L+ EGFR mutant NSCLC (NCT06074588), and 2L EGFR mutant NSCLC (NCT06305754) and a Phase 3 study of sac-TMT in China in patients with 2L EGFR mutant NSCLC (NCT05870319) are ongoing. Additionally two Phase 3 global studies of sac-TMT plus pembrolizumab in patients with metastatic NSCLC expressing programmed death ligand 1 (PD-L1) 50% (NCT06170788) and resectable NSCLC not achieving pathological complete response (NCT06312137) are ongoing.

Patients with previously treated inoperable advanced gastric/GEJ adenocarcinoma were enrolled to receive sac-TMT monotherapy at 5 mg/kg SECOND QUARTER OF W until disease progression or unacceptable toxicity in Phase 2 expansion cohort of KL264-01 study (NCT04152499). Patients with heavily pre-treated gastric/GEJ cancer were enrolled first, and then the cohort was amended to enroll patients with only one prior therapy of chemotherapy and anti-PD-1/L1 therapy. The data cut-off date was November 22, 2023.

As of the Data Cut-off Date, a total of 48 patients were enrolled and followed up for at least 9 weeks. 24 patients (50.0%) had received one prior line of therapy (2L), while 24 patients (50.0%) had received 2 prior lines of therapy (3L+). 40 patients (83.3%) had received prior anti-PD-1/L1 inhibitors.

Of 41 response-evaluable patients (defined as 1 on-study scans), the objective response rate (ORR) was 22.0% (9 partial responses, 2 pending confirmation) and disease control rate (DCR) was 80.5%. The ORRs in the 2L and 3L+ setting were 27.3% (including 2 pending confirmation) and 15.8%, respectively. Median duration of response (DoR) was 7.5 months.

In the subset of 3L+ patients (n=24 including 54.2% of patients with 4 prior lines of therapy) with more mature follow-up (median follow up of 14.6 months), the median progression free survival (mPFS) was 3.7 months (95% CI: 2.6, 5.4) and median overall survival (mOS) was 7.6 months (95% CI: 5.3, 15.5). The most common Grade 3 TRAEs were anemia (20.8%), neutrophil count decreased (18.8%), WBC decreased (12.5%) and neutropenia (6.3%). No TRAEs leading to treatment discontinuation or deaths occurred.

No neuropathy or drug-related ILD/pneumonitis was reported. A Phase 3 global study of sac-TMT monotherapy versus standard of care (SOC) chemotherapy in 3L+ gastric/GEJ adenocarcinoma is being planned.