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Atezolizumab Stumbles in Triple Negative Breast Cancer Study: SABCS 2024 Results with Charles Geyer

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Presented by Dr. Charles Geyer at SABCS 2024

Introduction

Triple-negative breast cancer (TNBC) remains one of the most challenging subtypes of breast cancer to treat, primarily due to its aggressive nature, high genomic instability, and limited targeted therapies. In the GeparDouze (NSABP B59) Phase III clinical trial, researchers evaluated the role of atezolizumab, an anti-PD-L1 immune checkpoint inhibitor, combined with chemotherapy for patients with Stage II and III TNBC.

Dr. Charles Geyer presented the trial’s findings at SABCS 2024, discussing the rationale, outcomes, challenges, and future implications for immunotherapy in breast cancer treatment.

“We recognize that That combination also made them immunogenic. And so there was always recognition. Over time we came to appreciate that when you see the immune system in there where there’s immune lymphocytes in the tumor, those tumors, those patients seem to do better even in the absence of drug therapy and with drug therapy they do better still.” said Dr. Geyer

Key Background: Immunogenic Potential of TNBC

TNBC is characterized by:

  • High Tumor Mutation Burden: Makes it more sensitive to chemotherapy.
  • Immunogenic Tumors: TNBC often triggers an immune response, visible as tumor-infiltrating lymphocytes (TILs).
  • Checkpoint Inhibition: Cancer cells exploit immune checkpoints like PD-L1 to suppress T-cell activity.

The rationale for combining immune checkpoint inhibitors like atezolizumab with chemotherapy is to enhance the body’s immune response to cancer while reducing tumor burden.

Study Design: GeparDouze (NSABP B59)

The trial focused on patients with Stage II and III TNBC undergoing neoadjuvant chemotherapy, followed by atezolizumab or placebo as adjuvant therapy. Key features included:

  • PD-L1 Status: Initially not a requirement but later incorporated as a key biomarker for analysis.
  • Patient Enrollment: Conducted across Germany, the U.S., Canada, and Spain over 41 months.
  • Standard of Care Changes: Mid-trial protocol amendments allowed therapies like capecitabine for non-pathologic complete responders (non-PCR).

Findings and Key Results

  1. PD-L1 Status
    Unlike in metastatic TNBC, PD-L1 status did not differentiate outcomes in this neoadjuvant setting. Researchers speculate this may be due to changes in tumor dynamics caused by chemotherapy.
  2. Toxicities and Safety
    • Common immune-related toxicities: Thyroid dysfunction (hyperthyroidism/hypothyroidism).
    • Rare but serious events: Adrenal insufficiency, colitis, and other immune-related adverse events.
    • Placebo Comparison: Blinded evaluation revealed incremental toxicities related to atezolizumab.
  3. Survival Rates
    • Both arms of the trial demonstrated remarkable 4-year overall survival of 90%.
    • Minimal difference between treatment and placebo groups.
  4. Study Challenges
    • Longer trial duration (41 months) compared to Keynote-522 (19 months).
    • Introduction of therapies like capecitabine and olaparib mid-trial influenced outcomes.
  5. Heterogeneity in Patient Response
    Subgroup analysis revealed certain patients, such as those with:
    • Node-positive disease.Larger tumors.High levels of tumor-infiltrating lymphocytes (TILs).
    These groups showed potential signs of benefit from atezolizumab, suggesting opportunities for biomarker-driven treatment approaches.
  • 📚 Chapters 0:00 Introduction
  • 0:15 Standard of Care in Triple-Negative Breast Cancer
  • 0:45 Immunogenicity and the Role of the Immune System
  • 1:28 Rationale for Checkpoint Inhibitors
  • 2:45 Overview of the GeparDouze Trial Design
  • 3:30 PD-L1 Status and Its Impact on Results
  • 4:15 Immune-Related Toxicities and Safety Findings
  • 6:10 Differences Between GeparDouze and Keynote 522
  • 7:00 Impact of Changing Standard of Care During the Study
  • 8:15 Study Accrual and Challenges
  • 9:30 Survival Rates and Long-Term Outcomes
  • 11:00 Heterogeneity in Patient Outcomes and Subgroups
  • 12:15 Future Directions: Biomarker Identification and Translational Research

Conclusion

While the GeparDouze trial did not demonstrate significant survival benefits or alter the standard of care for TNBC, it underscores key learnings:

  • Immune checkpoint inhibitors hold promise for high-risk TNBC subgroups.
  • Identifying reliable biomarkers will be essential for patient selection.
  • Translational research is critical to unlocking the full potential of immunotherapy.

As Dr. Geyer concluded, the study highlights the complexity of TNBC and the need for precision medicine approaches to optimize treatment outcomes.

“The addition of atezolizumab to neoadjuvant chemotherapy did not improve pathologic complete response rates in early, high-risk triple-negative breast cancer” stated Geyer.

Key Takeaways

  • The role of atezolizumab in TNBC remains an active area of research.
  • Future trials must prioritize biomarker discovery to identify patients most likely to benefit.
  • TNBC treatment continues to evolve, and integrating immunotherapy earlier in the treatment sequence may improve outcomes for high-risk populations.
IFN-alpha and plasmacytoid dendritic cells in TNBC FinXX Trial
VIDEO: FDA Approves Atezolizumab / Tecentriq Hybreza For Subcutaneous PD-(L)1 Cancer Immunotherapy in NSCLC

Join the Conversation

What are your thoughts on immunotherapy for triple-negative breast cancer? Do you believe biomarkers will guide future treatment strategies? Share your insights in the comments below.

Tags and Hashtags

#TripleNegativeBreastCancer #TNBC #BreastCancerResearch #GeparDouze #Atezolizumab #CheckpointInhibitors #PDL1 #BreastCancerAwareness #SABCS2024 #PrecisionMedicine #NSABPB59 #Immunotherapy #CancerClinicalTrials #OncologyResearch

https://www.esmoopen.com/article/S2059-7029(24)01483-2/fulltext

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