China SBP Group (HKEX: 01177) has announced that its subsidiary, Chia Tai Tianqing Pharmaceutical Group Co., Ltd., presented new Phase II clinical data for its self-developed Class 1 innovative drug, TQB3616 (marketed as Cytochaser®), at the 2026 American Society of Clinical Oncology (ASCO) annual meeting.

The data focused on patients with hormone receptor (HR)-positive, HER2-negative advanced breast cancer who had previously progressed after treatment with a CDK4/6 inhibitor combined with endocrine therapy.

The study, named TQB3616-II-04 (NCT06702618), was a prospective, multi-center, single-arm trial evaluating the efficacy and safety of TQB3616 combined with fulvestrant in this patient population.

The primary endpoint was the confirmed objective response rate (ORR) as assessed by an independent review committee or investigators.

Secondary endpoints included progression-free survival (PFS), clinical benefit rate (CBR), disease control rate (DCR), and safety.

As of April 15, 2026, 35 patients were enrolled with a median follow-up of 10.8 months.

The patient population was highly representative of real-world post-resistance cases, with a median age of 56 years and 71.4% having visceral metastases, including liver, lung, and brain metastases.

All patients had prior CDK4/6 inhibitor plus endocrine therapy, and 37.1% had received prior chemotherapy.

In the 34 efficacy-evaluable patients, the TQB3616 combination regimen demonstrated potent anti-tumor activity.

The confirmed ORR was 32.4%, meeting the primary study endpoint.

The DCR was 88.2% and the CBR was 82.4%.

The median time to response was 3.7 months.

Notably, the median PFS and median duration of response had not yet been reached, with a 10-month PFS rate of 61.8%, indicating promising potential for sustained disease control.

This efficacy outcome holds significant clinical importance for patients who have failed prior CDK4/6 inhibitor therapy and have a high incidence of visceral metastases.

The study suggests TQB3616 not only has clear anti-tumor activity but can also maintain a durable therapeutic benefit in a resistant setting.

Regarding safety, the overall profile was consistent with previous studies, with no new safety signals identified.

The incidence of Grade 3 or higher treatment-related adverse events was 40.0%.

There were no permanent treatment discontinuations due to TRAEs and no treatment-related deaths.

The incidence of Grade 3 or higher neutropenia, a key concern with traditional CDK4/6 inhibitors, was only 5.7%, aligning with the drug's lower CDK6 inhibitory activity.

Overall, the TQB3616 combination regimen demonstrated a manageable and favorable safety profile.