China Greenlights Potent New Drug for Most Common Breast Cancer Subtype

CHENGDU, China – February 06, 2026 – China's National Medical Products Administration (NMPA) has approved a groundbreaking new therapy for the most prevalent form of breast cancer, offering a significant new option for patients with advanced disease. Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. announced it has received marketing authorization for sacituzumab tirumotecan (sac-TMT) for adult patients with unresectable or metastatic HR-positive, HER2-negative (HR+/HER2-) breast cancer. The approval specifically targets a heavily pre-treated population who have exhausted endocrine therapy and at least one line of chemotherapy, a group with historically poor prognoses.

Redefining Outcomes in Advanced Breast Cancer

The approval is a direct result of the compelling data from the Phase III OptiTROP-Breast02 study, which demonstrated that sac-TMT more than doubled the time patients lived without their cancer progressing compared to standard chemotherapy. Patients receiving the new antibody-drug conjugate (ADC) had a median progression-free survival (PFS) of 8.3 months, a stark contrast to the 4.1 months observed in the chemotherapy group. This represents a 65% reduction in the risk of disease progression or death.

The study, whose results were significant enough to be featured as a Late-Breaking Abstract at the 2025 European Society for Medical Oncology (ESMO) Congress, enrolled a patient population with very advanced and difficult-to-treat disease. Nearly all participants (95.7%) had visceral metastases—cancer that has spread to internal organs—and three-quarters (75.9%) had liver metastases, which are typically associated with a worse outlook. All patients had previously been treated with the current standard of care, including CDK4/6 inhibitors and taxane-based chemotherapy, with over half having undergone two or more prior chemotherapy regimens.

Beyond halting cancer progression, sac-TMT also proved more effective at shrinking tumors. The objective response rate (ORR) was 41.5% for patients on sac-TMT, compared to just 24.1% for those on chemotherapy. This benefit was consistent across all patient subgroups, including those with HER2-low and HER2-zero tumors, broadening the drug's applicability within the diverse HR+/HER2- population. For a patient group where conventional chemotherapy offers limited benefit—often providing a PFS of only four to five months—these results mark a pivotal advancement in the treatment landscape.

The Power of Precision: A Look at TROP2-Directed ADCs

Sacituzumab tirumotecan belongs to a revolutionary class of cancer treatments known as antibody-drug conjugates (ADCs). Often described as "biological missiles," ADCs are designed to deliver potent chemotherapy agents directly to cancer cells while largely sparing healthy tissue. They achieve this by linking a powerful cytotoxic payload to a monoclonal antibody that specifically seeks out a target protein, or antigen, that is overexpressed on the surface of tumor cells.

In the case of sac-TMT, the target is TROP2, a protein found in high levels on the surface of many solid tumors, including about 70% of all breast cancers. Kelun-Biotech's proprietary technology gives sac-TMT a unique design. It utilizes a novel, stable linker to attach a highly potent payload—a derivative of the topoisomerase I inhibitor belotecan—to the anti-TROP2 antibody.

This design allows for a high drug-to-antibody ratio (DAR) of 7.4, meaning each antibody carries a substantial amount of the cancer-killing drug. Once the ADC binds to TROP2 on a cancer cell, it is internalized, and the linker releases the payload inside the cell, causing DNA damage that leads to cell death. Furthermore, the payload is membrane-permeable, enabling a "bystander effect" where it can diffuse out of the targeted cell and kill neighboring cancer cells that may not even express TROP2, amplifying the drug's therapeutic impact within the tumor microenvironment.

This approval marks the fourth indication for sac-TMT in China and further establishes the clinical importance of targeting TROP2. The drug was notably the world's first TROP2 ADC approved for lung cancer, signaling the broad potential of this therapeutic strategy across different oncology settings.

A Chinese Innovator on the Global Stage

This latest regulatory milestone cements Kelun-Biotech's position as a formidable player in China's rapidly advancing biopharmaceutical sector and on the global stage. As a subsidiary of the established Kelun Pharmaceutical, the company has strategically focused on developing innovative drugs for major diseases, with a particularly strong emphasis on its proprietary ADC platform, OptiDC™. With two ADCs now approved for marketing and multiple others in its pipeline, the company is at the forefront of this cutting-edge technology.

The global potential of sac-TMT was validated in May 2022 when Kelun-Biotech entered into a landmark licensing agreement with global pharmaceutical giant MSD (the tradename of Merck & Co., Inc.). The deal, potentially worth up to $1.4 billion, granted MSD exclusive rights to develop and commercialize the drug (known as MK-2870 in its pipeline) in all territories outside of Greater China.

This partnership has since expanded, with MSD now evaluating MK-2870 in 16 ongoing global Phase III studies for various cancers, both as a monotherapy and in combination with its blockbuster immunotherapy, KEYTRUDA® (pembrolizumab). The immense confidence in the drug's future was further underscored when investment firm Blackstone Life Sciences committed $700 million to co-fund a portion of MSD's development costs. This collaboration not only provides significant financial backing but also accelerates the drug's path to patients worldwide, showcasing how Chinese innovation is increasingly shaping the future of global medicine.

From Approval to Access: The Path to Patients

Receiving regulatory approval is a critical step, but ensuring broad patient access is the ultimate goal. For sac-TMT, the path forward in China looks promising. The drug has already received six Breakthrough Therapy Designations from the NMPA across different cancer types, a status reserved for therapies that demonstrate substantial improvement over available treatments for serious conditions.

Crucially, two of the drug's previous approvals—for specific types of non-small cell lung cancer and triple-negative breast cancer—are already included in China's National Reimbursement Drug List (NRDL). Inclusion in the NRDL dramatically lowers the cost of innovative medicines for patients, making them widely accessible across the country. This precedent suggests a favorable outlook for the new HR+/HER2- breast cancer indication to eventually be added to the list, which would bring this vital new treatment within reach of a much larger patient population.

Meanwhile, the clinical development of sac-TMT continues to push forward. New Phase III studies have been initiated both globally and in China to evaluate the drug in chemotherapy-naïve HR+/HER2- breast cancer patients, exploring its potential as an even earlier treatment option. As researchers continue to unlock its full capabilities, sac-TMT stands poised to become a cornerstone of therapy for a growing number of cancer patients in China and around the world.