Sac-TMT Posts Phase 3 OS Win but Faces Steep Pricing and Rival Crowding

Kelun-Biotech's Sac-TMT Extends OS in EGFR-Mutated NSCLC

Kelun-Biotech's sac-TMT demonstrated a significant extension in median overall survival (OS) to 25.9 months, compared to 17.4 months with pemetrexed plus platinum chemotherapy, in patients with EGFR-mutated non-small cell lung cancer (NSCLC) during the Phase III OptiTROP-Lung04 trial. This positive outcome was observed after a median follow-up of 32.3 months, with MSD holding the rights to sac-TMT outside Greater China.

• The Phase III OptiTROP-Lung04 trial showed that sac-TMT extended median overall survival to 25.9 months, a substantial improvement over the 17.4 months achieved with the comparator arm. This data, presented after a median follow-up of 32.3 months, underscores the drug's potential in treating EGFR-mutated NSCLC.
• The trial evaluated sac-TMT against a standard treatment regimen of pemetrexed plus platinum chemotherapy. The study specifically focused on patients with EGFR-mutated non-small cell lung cancer, addressing a critical need within this defined patient subpopulation.
• While Kelun-Biotech developed sac-TMT, MSD holds the commercial rights to the drug outside of Greater China. The sustained survival gain observed in the OptiTROP-Lung04 trial places a strategic onus on MSD for the drug's broader global development and market access.

Sac-TMT's OS Advantage Over Standard Chemo in EGFR-mutated NSCLC

For patients with epidermal growth factor receptor-mutated locally advanced/metastatic non-small cell lung cancer whose disease has progressed on or after osimertinib and platinum-based chemotherapy, no uniformly accepted standard of care exists and the treatment landscape is fragmented. In a US retrospective analysis of patients who initiated a new line of therapy between November 13, 2015 and June 30, 2021 following prior osimertinib and platinum-based chemotherapy, multiple regimens were used and none was predominant. In the reference cohort (N = 273), median real-world progression-free survival and real-world overall survival were 3.3 and 8.6 months, respectively, and confirmed real-world objective response rate (response evaluable, n = 123) was 13.0%. In the matched subset (n = 126) resembling the HERTHENA-Lung01 (NCT04619004) population of patritumab deruxtecan (HER3‑DXd), after propensity score weighting, median real-world progression-free survival and real-world overall survival were 4.2 and 9.1 months, respectively, and confirmed real-world objective response rate (response evaluable, n = 57) was 14.1%.

Investigational dual-targeting and next-generation approaches have reported activity in molecularly defined subsets that exceeds this benchmark in published studies. JMT101 plus osimertinib 160 mg in EGFR exon 20 insertion-positive disease (121 patients enrolled, NCT04448379) reported confirmed objective response rate of 36.4%, median progression-free survival of 8.2 months, rash (76.9%) and diarrhea (63.6%), with responses in distinct 20ins variants and intracranial lesions, intracranial disease control rate of 87.5% and confirmed intracranial objective response rate of 25%; in platinum-refractory disease (n = 53), confirmed objective response rate was 34.0%, median progression-free survival was 9.2 months and median duration of response was 13.3 months. Aumolertinib plus anlotinib as first-line therapy in EGFR-mutant patients with brain metastases (87 patients enrolled, GASTO-1063, NCT04978753) reported median intracranial progression-free survival of 30.2 months, median overall progression-free survival of 22.5 months, median overall survival was not reached, and intracranial objective response rate and intracranial disease control rate were 71.3% and 93.1%. Avitinib 150-300 mg twice daily in T790M-positive disease (16 patients, NCT02330367) reported nine (60.0%) with partial response and five (33.3%) with stable disease, median progression-free survival and overall survival of 247 days (95% confidence interval (CI): 154.8-339.2) and 536 days (95%CI: 363.6-708.4), median intracranial progression-free survival of 142 days (95% CI 31.1-252.9) in seven brain metastases patients, and blood-brain barrier penetration rate of 0.046%-0.146%. A case report of brigatinib and cetuximab plus icotinib in advanced disease harboring EGFR L858R-T790M-cis-G796S and L718Q following progression with osimertinib reported more than 9 months of progression-free survival.

Standard first-line tyrosine kinase inhibitors and continuation strategies provide additional context for comparison. In Vietnam, 211 patients received Erlotinib (n = 74), Gefitinib (n = 85), Afatinib (n = 34) or Osimertinib (n = 18), with overall response rate of 76.7%, Osimertinib at 83.4%, Afatinib at 73.6%, Erlotinib at 77.1%, and Gefitinib at 76.5%; median progression-free survival in the Gefitinib group was 12.2 months (95% CI: 11.1-13.2), 13.4 months (95% CI: 10.6-16.2) in the Erlotinib group, 18.4 months (95% CI: 10.1-26.8) in the Afatinib group and 25.3 months in the Osimertinib group (p = 0.001). In the afatinib expanded access program (NCT01649284) in 322 patients receiving afatinib 40 mg once daily, 17.1% and 69.9% achieved objective response and disease control, with drug-related adverse events in 89.4% including 7.8% serious, diarrhea (77.0%) and rash (36.0%), dose reductions in 31.1%, and discontinuation due to diarrhea (1.6%) or rash/acne (0.3%). Osimertinib continuation beyond progression in 47 of 76 patients with progression was associated with median second progression-free survival of 12.6 months and longer overall survival compared with discontinuation (11.2 vs. 6.1 months, P = 0.02), while 21 patients receiving local consolidation radiation had median progression-free survival of 15.5 months; EGFR C797 and L792 (26%) mutations observed exclusively in T790M-preserved cases and MET amplification (14%) were common resistance alterations. Osimertinib 80 mg in T790M-positive advanced disease with brain evaluation (89 patients, ASTRIS Korean subset) reported intracranial objective response rate and disease control rate of 62.5% (95% confidence interval (CI), 38.3-82.6%) and 93.8% (95% CI, 74.3-99.3%) and median intracranial progression-free survival of 13.0 (95% CI, 7.21-18.8) months.

Unpacking the OptiTROP-Lung04 Phase III Trial Design

Key trials in EGFR-mutated NSCLC span first-line advanced, CNS-metastatic, and perioperative settings, evaluating third-generation TKIs as monotherapy and in combination. Designs range from single-arm phase 2 studies to open-label randomised phase 3 trials, with endpoints centered on progression-free survival, objective response rate, and survival.

Addressing Unmet Needs in EGFR-mutated NSCLC with Sac-TMT

Recent literature in EGFR-mutated non-small cell lung cancer (NSCLC) concentrates on populations with limited therapeutic alternatives and poor outcomes after standard EGFR tyrosine kinase inhibitors. Efforts over the past 3 years target uncommon genotypes, central nervous system disease, and progression after osimertinib.

• NSCLC with uncommon EGFR mutations: Patients harboring G719X, L861Q, S768I, single and compound mutations, excluding exon 20 insertions, are evaluated as a heterogeneous population with reduced responsiveness to EGFR tyrosine kinase inhibitors (TKIs) and limited therapeutic alternatives, including investigation of osimertinib 80 mg daily, lazertinib 240 mg daily, afatinib, and zipalertinib.

• EGFR exon 20-mutant NSCLC: Patients with exon 20 insertions, duplications, and deletions-insertions, historically marked by innate resistance to previously approved EGFR tyrosine kinase inhibitors and poor prognosis, are targeted with exon 20-targeting agents including amivantamab, mobocertinib, and zipalertinib, as well as combination strategies with platinum-based chemotherapy.

• CNS metastases including leptomeningeal disease: Patients with brain metastases and leptomeningeal metastases, including de novo brain metastases, asymptomatic or mildly symptomatic brain metastases after unsuccessful treatment with first-generation or second-generation EGFR TKIs, and Meckel's cave metastasis, are a focus for intracranial activity of lazertinib and osimertinib alone or with local ablative therapy.

• Progression on osimertinib with acquired resistance: Patients who progress on osimertinib with resistance mechanisms including MET amplification, EGFR C797X-acquired mutation, human epidermal growth factor 2 (HER2) amplification, and transformation to small cell and squamous cell lung cancer are targeted with dual EGFR-MET inhibition with crizotinib, capmatinib, savolitinib, or tepotinib plus osimertinib, and investigational antibody-drug conjugates which include targets to MET amplification, HER3, Trop2, and EGFR, while platinum-based chemotherapy is the current standard treatment option with dismal outcomes and access to subsequent treatments and CNS progression are confirmed unmet needs.

Sac-TMT's OS Breakthrough Reshapes EGFR-Mutated NSCLC Treatment

The recent Phase III OptiTROP-Lung04 trial results for sacituzumab tirumotecan (sac-TMT) mark a pivotal moment for patients with EGFR-mutated non-small cell lung cancer (NSCLC) who have progressed following EGFR tyrosine kinase inhibitor (TKI) therapy. This patient population faces a critical need for more effective subsequent treatment options, as disease progression is inevitable after initial targeted therapy. The trial's demonstration of a significant extension in median overall survival (OS) to 25.9 months with sac-TMT, compared to 17.4 months with standard pemetrexed plus platinum chemotherapy, is a substantial clinical achievement.

This outcome positions sac-TMT, a TROP2-directed antibody-drug conjugate (ADC), as a strong contender for a new second-line standard of care. The literature consistently highlights TROP2 as a promising therapeutic target in NSCLC, and sac-TMT has distinguished itself by showing improvements in both progression-free survival and overall survival over chemotherapy in this specific setting. This success not only validates the TROP2 ADC class but also underscores the potential for targeted cytotoxic delivery to improve patient outcomes significantly.

However, the path forward is not without considerations. Cost-effectiveness analyses suggest that sac-TMT, at its current pricing, may not be deemed cost-effective in certain healthcare systems, which could impede broad patient access without strategic pricing adjustments or inclusion in national reimbursement programs. Furthermore, while sac-TMT exhibits a manageable safety profile, ADCs are known to carry a risk of specific adverse events, including stomatitis, nausea, alopecia, and interstitial lung disease, necessitating vigilant monitoring and proactive management. The burgeoning landscape of TROP2 ADCs, with other agents like datopotamab deruxtecan also showing promise, indicates a future competitive environment where ongoing differentiation based on long-term efficacy, safety, and patient quality of life will be crucial for sustained market leadership.