Kelun’s Merck-Partnered ADC Delivers Phase III Win in First-Line PD-L1-Negative Lung Cancer

Sacituzumab tirumotecan plus Keytruda improves progression-free survival in advanced NSCLC, expanding potential role of ADC-immunotherapy combinations. Kelun-Biotech’s antibody-drug conjugate (ADC) sacituzumab tirumotecan (sac-TMT), in combination with Merck & Co.’s Keytruda (pembrolizumab), has achieved a late-stage clinical success in first-line non-small-cell lung cancer (NSCLC), strengthening the potential of ADC-immunotherapy combinations across a broader patient population.

The Phase III OptiTROP-Lung06 trial met its primary endpoint, demonstrating that sac-TMT plus Keytruda delivered a statistically significant and clinically meaningful improvement in progression-free survival (PFS) compared with Keytruda combined with standard chemotherapy in patients with locally advanced or metastatic NSCLC.

The positive results focus specifically on patients with PD-L1 tumour proportion scores below 1% — a population with limited response to existing immunotherapy approaches.

Expanding Treatment Options in PD-L1-Negative NSCLC

The OptiTROP-Lung06 study enrolled 432 patients with previously untreated locally advanced or metastatic NSCLC whose tumours had PD-L1 expression levels below 1%.

Patients were randomised to receive either:

• Sacituzumab tirumotecan plus Keytruda

• Keytruda plus pemetrexed and platinum-based chemotherapy
  

The study’s primary endpoint was progression-free survival assessed by blinded independent central review (BICR).

Top-line results showed the ADC combination achieved a significant improvement in PFS compared with the chemotherapy-based regimen.

The combination also demonstrated a positive trend in overall survival, although further follow-up will be required to determine the full impact.

Kelun reported that the safety profile remained consistent with previous studies, with no new safety concerns identified.

The company plans to discuss the results with Chinese regulatory authorities.

Merck’s Strategic Bet on Sac-TMT

The latest results reinforce Merck’s growing investment in sac-TMT, following its agreement with Kelun-Biotech in 2022 for exclusive rights outside China.

Under the partnership, Merck gained global development and commercialisation rights for the TROP2-targeting ADC, while Kelun continues to develop the asset in China.

Sac-TMT, marketed as Jia Tai Lai in China, has already received approval in four indications, including:

• Triple-negative breast cancer

• EGFR mutation-positive NSCLC

• HR-positive/HER2-negative breast cancer
  

The ADC is now being evaluated across multiple tumour types as Merck looks to expand its oncology pipeline ahead of future market challenges.

Building Momentum Across Lung Cancer Studies

The OptiTROP-Lung06 success follows another Phase III win for the combination in first-line NSCLC.

In the OptiTROP-Lung05 trial, sac-TMT plus Keytruda demonstrated improved PFS compared with Keytruda alone in treatment-naïve patients with PD-L1-positive NSCLC.

Additional data presented at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting showed the combination reduced the risk of disease progression or death by 65% compared with Keytruda monotherapy after a median follow-up of 10.5 months.

Together, the results suggest sac-TMT could have potential across a wide range of NSCLC patients, regardless of PD-L1 status.

Kelun CEO Michael GE said the combined findings from OptiTROP-Lung05 and OptiTROP-Lung06 highlight the “strong synergetic effect” of sac-TMT combined with Keytruda and support its potential to benefit the broader first-line NSCLC population.

The Growing Role of ADCs in Oncology

ADC technology has become one of the most competitive areas in oncology development, combining the targeting ability of antibodies with the cancer-killing effects of cytotoxic payloads.

By selectively delivering therapy to tumour cells, ADCs aim to improve efficacy while reducing systemic toxicity compared with traditional chemotherapy.

Sac-TMT is currently being investigated in 10 registrational lung cancer studies, including five trials in China and five global studies.

Beyond lung cancer, the ADC has also achieved a late-stage success in endometrial cancer and forms part of Merck’s wider TroFuse Phase III programme evaluating ADC-based combinations across multiple tumour types.

What This Means for the NSCLC Market

The latest Phase III success adds further momentum to the shift towards combination approaches in lung cancer treatment.

While PD-1 inhibitors such as Keytruda have transformed NSCLC care, many patients — particularly those with low or absent PD-L1 expression — continue to require more effective treatment options.

If future regulatory submissions are successful, sac-TMT plus Keytruda could strengthen Merck’s position in a highly competitive lung cancer market while demonstrating the expanding role of ADCs beyond traditional chemotherapy-based treatment pathways.

For pharmaceutical companies, the result also highlights the growing importance of strategic partnerships with biotech innovators as major players look to build next-generation oncology portfolios.

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