On May 23, 2025 Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. (6990.HK, the "Company") reported it will present results from six clinical studies, including data on its TROP2 ADC sac-TMT, anti-PD-L1 mAb tagitanlimab, and RET inhibitor KL590586 (A400/EP0031) at the 2025 American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Annual Meeting scheduled to take place in Chicago, Illinois, USA from May 30 to June 3 (Press release, Kelun, MAY 23, 2025, View Source [SID1234653371]).
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The study abstracts were published on the ASCO (Free ASCO Whitepaper) website on May 22, 2025 (CDT), with key highlights summarized below:
1. Sac-TMT in patients with previously treated advanced epidermal growth factor receptor (EGFR)-mutated non-small-cell lung cancer (NSCLC): Results from the randomized OptiTROP-Lung03 study
Oral Presentation: June 1, 10:12-10:24 CDT (Abstract #8507: Lung Cancer – Non-Small Cell Metastatic)
A total of 137 patients with advanced EGFR-mutant NSCLC who had progressed after EGFR-tyrosine kinase inhibitor (TKI) and platinum-based chemotherapy were randomized (2:1) to receive sac-TMT (5 mg/kg once every 2 weeks (Q2W)) or docetaxel (75 mg/m2 once every 3 weeks (Q3W)). The median follow-up of 12.2 months (data cutoff: December 31, 2024).
Sac-TMT achieved statistically significant and clinically meaningful outcomes compare d to docetaxel: confirmed objective response rate (ORR) (blinded independent review committee (BIRC): 45.1% vs 15.6%, one-sided p=0.0004), progression-free survival (PFS) (BIRC: median 6.9 vs 2.8 months, hazard ratio (HR)= 0.30, one-sided p<0.0001; investigator (INV): median 7.9 vs 2.8 months, HR=0.23). With 36.4% of patients in docetaxel group crossing over to receive sac-TMT, median overall survival (OS) was not reached (NR) for both groups (HR 0.49, one-sided p=0.007). The median OS analysed by pre-specified rank-preserving structural failure time (RPSFT) model adjusted for crossover was 9.3 months for docetaxel and NR for sac-TMT (HR=0.36).
Grade ≥ 3 treatment-related adverse events (TRAEs) occurred in 56.0% of patients in sac-TMT group vs 71.7% in docetaxel group. No cases of interstitial lung disease (ILD) were reported in sac-TMT group.
These results led to the approval of sac-TMT in EGFR mutation-positive locally advanced or metastatic non-squamous NSCLC following progression on EGFR-TKI therapy and platinum-based chemotherapy in China, which marks the first approval for a TROP2 ADC in lung cancer globally.
2. Sac-TMT as first-line treatment for unresectable locally advanced/metastatic triple-negative breast cancer (a/m TNBC): Initial results from the Phase 2 OptiTROP-Breast05 study
Rapid Oral Presentation: May 30, 15:45-15:51 CDT (Abstract #1019: Breast Cancer – Metastatic)
As of November 18, 2024, a total of 41 patients with a/m TNBC who had not received prior treatment for advanced disease (median age 55 years; 43.9% Eastern Cooperative Oncology Group (ECOG) Performance status (PS) 1; 78.0% PD-L1 combined positive score (CPS)<10) were enrolled to receive sac-TMT monotherapy at 5 mg/kg Q2W until disease progression or unacceptable toxicity. The median follow-up was 18.6 months.
The ORR was 70.7% and the disease control rate (DCR) was 92.7%. Median duration of response (DoR) was 12.2 months, while the median PFS was 13.4 months. Among the 32 patients with PD-L1 CPS <10, the ORR was 71.9% and the DCR was 93.8%. The median PFS in this subgroup was 13.1 months.
TRAEs of grade 3 or higher occurred in 63.4% of patients. No treatment-related deaths occurred, and there were no reports of neuropathy or ILD/pneumonitis.
3. Sac-TMT in combination with tagitanlimab (anti-PD-L1) in first-line (1L) advanced NSCLC: Non-squamous cohort from the Phase 2 OptiTROP-Lung01 study
Poster Presentation: May 31, 13:30-16:30 CDT (Abstract #8529: Lung Cancer – Non-Small Cell Metastatic)
Advanced NSCLC patients with no prior systemic therapy and no actionable genomic alterations were enrolled to receive sac-TMT (5 mg/kg Q3W or Q2W) plus tagitanlimab (1,200 mg Q3W or 900 mg Q2W) until disease progression or unacceptable toxicity. As of December 30, 2024, 81 patients with non-squamous histology were enrolled.
After median follow-up of 17.1 months, confirmed ORR was 59.3%; Median DoR was 16.5 months; Median PFS was 15.0 months. Among patients with PD-L1 tumor proportion score (TPS)≥50%, the confirmed ORR was 77.8%; median PFS was 17.8 months; while for patients with PD-L1 TPS≥1%, the confirmed ORR was 68.1%; median PFS was 17.8 months. Among patients with PD-L1 TPS< 1%, confirmed ORR was 47.1%; median PFS was 12.4 months. Most common Grade≥3 TRAEs were neutrophil count decreased (45.7%), anemia (16.0%), white blood cell count decreased (14.8%) and stomatitis (11.1%). No TRAE led to treatment discontinuation or death.
4. Sac-TMT in patients with previously treated locally advanced or metastatic (LA/M) NSCLC harboring uncommon EGFR mutations: Preliminary results from a Phase 2 Study
Poster Presentation: May 31, 13:30-16:30 CDT (Abstract #8615: Lung Cancer – Non-Small Cell Metastatic)
As of December 1, 2024, 42 advanced NSCLC patients who had progressed on or after systemic therapy were enrolled, including 23 patients with EGFR G719X in exon 18, S768I in exon 20, or L861Q in exon 21 and 19 patients with EGFR ex20ins. Patients received sac-TMT 5 mg/kg Q2W until disease progression or unacceptable toxicity.
After a median follow-up of 9.2 months, the ORR was 35.7% and the DCR was 85.7%. Responses were durable with the median DoR not yet reached. The median PFS was 9.5 months. In the subset of patients with uncommon non-ex20ins, the ORR was 34.8%; the median PFS was 10.9 months. In the subset of patients with ex20ins, the ORR was 36.8% and the median PFS was 9.0 months.
Grade ≥3 TRAEs occurred in 52.4% of patients. No TRAEs led to treatment discontinuation or death. No cases of ILD/pneumonitis were reported.
5. Tagitanlimab versus placebo in combination with gemcitabine and cisplatin (GP) as first-line treatment for recurrent or metastatic nasopharyngeal carcinoma (R/M NPC): Results from a randomized, double-blind, phase Phase 3 study
Oral Presentation: May 31, 14:27-14:39 CDT (Abstract #6004: Head and Neck Cancer).
Eligible R/M NPC patients who have not previously received systemic therapy were in 2:1 ratio randomly assigned to receive tagitanlimab or placebo (1200 mg, D1) in combination with cisplatin (80 mg/m2, D1) and gemcitabine (1000 mg/m2, D1 and D8) Q3W for up to 6 cycles followed by tagitanlimab or placebo monotherapy Q3W until disease progression, unacceptable toxicity, or withdrawal of consent. The median follow-up time was 11.7 months.
The PFS per blinded independent central review (BICR) was met with a 53% reduction in risk of progression or death (HR=0.47, one-sided P <0.0001). The median PFS was not reached in tagitanlimab plus GP arm and 7.9 months in placebo plus GP arm. The ORR per BICR was 81.7% in tagitanlimab plus GP arm and 74.5% in placebo plus GP arm, with a median DoR of 11.7 months and 5.8 months (HR=0.48), respectively. The OS benefit was observed in tagitanlimab plus GP arm vs placebo plus GP arm (median OS not reached for either arm; HR=0.62). Tagitanlimab also showed a manageable safety profile.
6. Results from a Phase 1 study of KL590586 in patients with advanced RET-mutant medullary thyroid cancer (MTC)
Poster Presentation: June 2, 9:00-12:00 CDT (Abstract #6098: Head and Neck Cancer)
As of September 20, 2024, 27 advanced RET-mutant MTC patients without prior selective RET inhibitors were enrolled and treated in the phase 1 part across 4 dose levels (20 to 90 mg once a day (QD)). The median follow-up was 19.0 months.
As of September 20, 2024, the confirmed ORR was 63.0% and the DCR was 100% for overall population. The confirmed ORR was 56.3% (9/16) and 62.5% (5/8) in patients with prior multikinase inhibitor (MKI) or treatment naïve, respectively. Median DoR was not reached, with the longest duration still ongoing at 25.8 months. Similarly, median PFS was not reached, with the 24-month PFS rate of 77.8%.
All patients experienced TRAEs, with grade ≥3 TRAEs occurred in 22.2% of patients. No TRAEs led to treatment discontinuation or death.
About sac-TMT
Sac-TMT, a core product of the Company, is a novel human TROP2 ADC in which the Company has proprietary intellectual property rights, targeting advanced solid tumors such as NSCLC, breast cancer (BC), gastric cancer (GC), gynecological tumors, among others. Sac-TMT is developed with a novel linker to conjugate the payload, a belotecan-derivative topoisomerase I inhibitor with a drug-to-antibody-ratio (DAR) of 7.4. Sac-TMT specifically recognizes TROP2 on the surface of tumor cells by recombinant anti-TROP2 humanized monoclonal antibodies, which is then endocytosed by tumor cells and releases KL610023 intracellularly. KL610023, as a topoisomerase I inhibitor, induces DNA damage to tumor cells, which in turn leads to cell-cycle arrest and apoptosis. In addition, it also releases KL610023 in the tumor microenvironment. Given that KL610023 is membrane permeable, it can enable a bystander effect, or in other words kill adjacent tumor cells.
In May 2022, the Company licensed the exclusive rights to MSD (the tradename of Merck & Co., Inc, Rahway, NJ, USA) to develop, use, manufacture and commercialize sac-TMT in all territories outside of Greater China (which includes Mainland China, Hong Kong, Macao and Taiwan).
To date, two indications for sac-TMT have been approved and marketed in China for the treatment of adult patients with unresectable locally advanced or metastatic TNBC who have received at least two prior systemic therapies (at least one of them for advanced or metastatic setting) and EGFR mutation-positive locally advanced or metastatic non-squamous NSCLC following progression on EGFR-TKI therapy and platinum-based chemotherapy. Sac-TMT became the first domestically developed and fully approved for marketing ADC in China with global intellectual property rights. It is also the world’s first TROP2 ADC to be approved for marketing in a lung cancer indication. In addition, two new indication applications for sac-TMT for the treatment of adult patients with EGFR-mutant locally advanced or metastatic NSCLC who progressed after treatment with EGFR-TKI therapy and with unresectable locally advanced, metastatic hormone receptor-positive (HR+) and human epidermal growth factor receptor 2-negative (HER2-) BC who have received prior endocrine therapy and other systemic treatments in the advanced or metastatic setting were accepted by the National Medical Products Administration (NMPA), and were (to be) reviewed via the priority review and approval process. As of today, the Company has initiated 8 registrational clinical studies in China. MSD has initiated 14 ongoing Phase 3 global clinical studies of sac-TMT as a monotherapy or with pembrolizumab[1] or other agents for several types of cancer. These studies are sponsored and led by MSD.
About Tagitanlimab
Tagitanlimab is the first PD-L1 mAb to receive authorization for the first-line treatment of NPC. Previously, the NMPA has approved the marketing in China of tagitanlimab used in combination with cisplatin and gemcitabine for the first-line treatment of patients with R/M NPC and monotherapy for the treatment of patients with recurrent or metastatic NPC who have failed after prior 2L+ chemotherapy, respectively.
About KL590586 (A400/EP0031)
KL590586(A400/EP0031) is a novel next-generation selective RET inhibitor for NSCLC, MTC and other solid tumors with a high prevalence of RET alterations. The Company are currently conducting pivotal clinical studies for both 1L and 2L+ advanced RET+ NSCLC as well as a phase 1b/2 clinical study for RET+ MTC and solid tumor in China.
In March 2021, The Company granted Ellipses Pharma Limited, a U.K.-based international oncology drug development company, an exclusive license to develop, manufacture and commercialize this agent outside Greater China and certain Asian countries under the code EP0031.
In March 2024, it was announced that EP0031/A400 was granted Fast Track designation by the Food and Drug Administration (FDA) for the treatment of RET-fusion positive NSCLC. In April 2024, EP0031/A400 was cleared by the FDA to progress into Phase 2 clinical development and is now open in the US, UK, EU and UAE.