A Real-World Retrospective Study of Sintilimab in Combination with Neoadjuvant Chemotherapy for Triple-Negative Breast Cancer

This retrospective study of 61 triple-negative breast cancer patients demonstrates that adding the PD-1 inhibitor sintilimab to neoadjuvant chemotherapy significantly improves pathological complete response and objective response rates while maintaining a manageable safety profile compared to chemotherapy alone.

The Gist

Imagine your body is a bustling city, and Triple-Negative Breast Cancer (TNBC) is a particularly stubborn, shape-shifting gang of criminals that has taken over a neighborhood. Because this gang lacks the usual "uniforms" (specific receptors) that other gangs wear, it's very hard for standard police tactics to catch them.

This study is like a report from a real-world police station (a hospital in Lanzhou, China) looking at two different strategies to clear out this criminal gang before they can build a permanent fortress.

The Two Strategies

The researchers looked at 61 patients (the "neighborhoods" being treated) and split them into two teams to see which strategy worked better:

1. The "Standard Patrol" (NAC Alone): This group received the usual heavy-duty chemotherapy. Think of this as sending in a massive SWAT team with big guns to blast the criminals. It's strong, but sometimes the criminals are too good at hiding or have already dug in deep.
2. The "Special Forces + Patrol" (NAC + Sintilimab): This group got the same heavy-duty guns, but they also added a special agent called Sintilimab.
   • The Analogy: Imagine the cancer cells are wearing "invisibility cloaks" that trick your body's own security guards (the immune system) into thinking they are harmless citizens. Sintilimab is like a high-tech scanner that strips away those cloaks. Once the cloaks are gone, your body's natural security guards can finally see the criminals, recognize them as enemies, and help the SWAT team take them down.

The Results: Who Won?

The study found that the team with the Special Forces (Sintilimab) did a much better job:

• Clearing the Streets (ORR): In the standard group, about 6 out of 10 neighborhoods were cleared of visible crime. In the Special Forces group, that number jumped to 8 out of 10.
• Total Elimination (pCR): This is the "gold standard"—did they wipe out every single trace of the gang, even the tiny, hidden ones?
  • Standard Patrol: Only about 1 in 3 neighborhoods were completely clean.
  • Special Forces: Nearly 2 in 3 neighborhoods were completely clean.
• The "Growth Meter" (Ki-67): They also checked a gauge that measures how fast the criminals were trying to multiply. The Special Forces group saw this number drop significantly, meaning the gang was much less active and less likely to grow back quickly.

Was It Dangerous?

Usually, when you add a powerful new weapon, you worry about friendly fire (side effects).

• The Verdict: The study found that adding the Special Forces didn't cause a massive increase in general chaos or injury to the city. The overall safety was very similar to the standard patrol.
• The One Caveat: The only thing that happened a bit more often with the Special Forces was a temporary dip in the city's "white blood cell" supply (leukopenia), which is like a short-term shortage of police officers. However, this was manageable and didn't stop the mission.

The Bottom Line

In simple terms, this study suggests that for this specific type of tough breast cancer, adding the "cloak-stripper" (Sintilimab) to the standard heavy guns (chemotherapy) makes the cleanup much more effective.

It's like upgrading from a standard flashlight to a night-vision camera: you can see the enemy better, catch more of them, and leave the neighborhood much safer, without causing too much extra damage to the city itself. This gives doctors and patients a very promising new tool to fight this disease before surgery.

Technical Summary

Technical Summary: A Real-World Retrospective Study of Sintilimab in Combination with Neoadjuvant Chemotherapy for Triple-Negative Breast Cancer

1. Problem Statement

Triple-Negative Breast Cancer (TNBC) is an aggressive subtype characterized by the lack of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) expression. Due to the absence of these targets, TNBC patients have limited treatment options and a higher risk of recurrence compared to other breast cancer subtypes. Neoadjuvant chemotherapy (NAC) is the standard of care for locally advanced TNBC, aiming to downstage tumors and assess pathological response. However, response rates to NAC alone vary, and there is a critical need to identify strategies that improve pathological complete response (pCR) rates and long-term outcomes. The integration of immune checkpoint inhibitors, specifically Programmed Death Protein 1 (PD-1) inhibitors, has emerged as a promising avenue, yet real-world evidence regarding the efficacy and safety of Sintilimab (a PD-1 inhibitor) combined with NAC in TNBC remains limited compared to randomized controlled trials.

2. Methodology

This study employed a retrospective cohort design to evaluate real-world clinical outcomes.

• Data Source & Period: Clinical data were collected from The First Hospital of Lanzhou University covering the period from July 2024 to July 2025.
• Study Population: The cohort consisted of 61 patients diagnosed with TNBC who underwent neoadjuvant therapy.
• Grouping: Patients were stratified into two groups based on their treatment regimen:
  • Combination Group (n=27): Received NAC plus Sintilimab.
  • Control Group (n=34): Received NAC alone.
• Endpoints:
  • Primary Endpoint: Pathological Complete Response (pCR) rate.
  • Secondary Endpoints: Objective Response Rate (ORR), safety profile (incidence and severity of adverse events), and changes in tumor proliferation markers (specifically Ki-67).
• Statistical Analysis: Comparative analyses were conducted to determine statistical significance (P-values) between the two groups regarding efficacy and safety metrics.

3. Key Contributions

• Real-World Evidence (RWE): This study provides crucial real-world data validating the efficacy of Sintilimab in a Chinese clinical setting, complementing existing data from controlled clinical trials.
• Specific Drug Evaluation: It focuses specifically on Sintilimab, a domestically developed PD-1 inhibitor in China, assessing its performance when integrated into standard NAC regimens for TNBC.
• Biomarker Correlation: The study links clinical outcomes (pCR/ORR) with biological markers, specifically the reduction in Ki-67 levels, offering insight into the mechanism of tumor proliferation suppression.
• Safety Profiling: It offers a detailed safety comparison, highlighting that while specific hematological toxicities (leukopenia) may increase, the overall safety burden remains manageable.

4. Key Results

The study demonstrated statistically significant improvements in efficacy for the Sintilimab combination group:

• Efficacy:
  • Objective Response Rate (ORR): The combination group achieved an ORR of 85.2%, significantly higher than the 58.8% observed in the NAC-alone group (P < 0.05).
  • Pathological Complete Response (pCR): The pCR rate was 59.3% in the Sintilimab group compared to 32.4% in the control group (P < 0.05).
  • Tumor Proliferation: Post-treatment Ki-67 levels were significantly lower in the combination group (P < 0.05), indicating a substantial reduction in tumor cell proliferation.
• Safety:
  • Overall Adverse Events (AEs): The total incidence of adverse events was comparable between the two groups (P > 0.05), suggesting no significant increase in overall toxicity burden.
  • Specific Toxicity: Leukopenia was observed more frequently in the Sintilimab group (P < 0.05), though this was noted as a manageable side effect within the study context.

5. Significance

This study concludes that adding Sintilimab to neoadjuvant chemotherapy significantly enhances therapeutic outcomes for TNBC patients without compromising overall safety.

• Clinical Impact: The substantial increase in pCR rates (nearly doubling from ~32% to ~59%) suggests that this combination could lead to improved event-free survival and potentially overall survival, addressing a major unmet need in TNBC management.
• Therapeutic Strategy: The findings support the adoption of PD-1 inhibitor-based combination regimens as a viable and effective strategy in the neoadjuvant setting, particularly in regions where Sintilimab is accessible.
• Future Directions: While the results are positive, the retrospective nature and the specific timeframe (2024–2025) suggest a need for larger, prospective, multi-center randomized controlled trials to confirm long-term survival benefits and refine the management of specific adverse events like leukopenia.