Isoflavones impair anti-PD1 efficacy in breast cancer, regardless of dietary fiber or fecal short-chain fatty acid levels - Report - MDSpire

Isoflavones impair anti-PD1 efficacy in breast cancer, regardless of dietary fiber or fecal short-chain fatty acid levels

  • By

  • Fabia de Oliveira Andrade

  • Kerrie B. Bouker

  • Melike Ozgul-Onal

  • Lu Jin

  • Idalia Cruz

  • William Helferich

  • Audrey Gao

  • Karla Andrade de Oliveira

  • Vivek Verma

  • Christopher Staley

  • Patricia L. Foley

  • Leena Hilakivi-Clarke

  • July 6, 2026

  • 0 min

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Isoflavones reduce the effectiveness of anti-PD1 treatment in breast cancer

Overview

This study investigates the impact of dietary isoflavones on the efficacy of anti-PD1 therapy in breast cancer models. Findings indicate that isoflavones may influence the effectiveness of anti-PD1 treatment, regardless of dietary fiber or fecal short-chain fatty acid levels.

Background

The role of diet in cancer immunotherapy response is an emerging area of research, particularly in breast cancer. Isoflavones, which are present in certain dietary fibers, may influence immune responses and treatment outcomes, although further investigation is needed.

Data Highlights

Diet TypeEffect on Anti-PD1
High-MACEffective
Low-MACEffective
High-MACi (with isoflavones)Not effective
Low-MAC + GenisteinNot effective

Key Findings

  • High-MAC diets increased fecal microbial diversity and SCFA levels.
  • Anti-PD1 therapy was effective in TNBC models with high-MAC or low-MAC diets.
  • The inclusion of isoflavones eliminated the responsiveness to anti-PD1 therapy.
  • Blocking ERα with tamoxifen enhanced sensitivity to anti-PD1 in both TNBC and ERα+ models.
  • High fecal SCFA levels alone did not predict responsiveness to anti-PD1 therapy.

Clinical Implications

Clinicians should consider the potential impact of dietary components on treatment outcomes in patients with hormone-sensitive breast cancer.

Conclusion

Further investigation into dietary influences on cancer treatment outcomes is warranted.

Related Resources & Content

  1. Isoflavones impair response to anti-PD1 therapy in murine breast cancer models, irrespective of dietary fiber and fecal short chain fatty acid levels - PMC, 2023
  2. Journal of Gastroenterology — Microbial Indicators for Enhancing Immune Checkpoint Inhibition in Cancer Treatment
  3. the asco post — Impact of Empirical Dietary Inflammatory Pattern on Survival Outcomes in Patients With Stage III Colon Cancer
  4. Archives of Toxicology (Springer) — In vitro evidence for estrogen receptor activity of selected phase II isoflavone metabolites
  5. Archives of Toxicology — Impact of Isoflavones on Human Breast Tissue and Thyroid Hormone Regulation: An In-Depth Safety Assessment
  6. The gut microbiome as a target in cancer immunotherapy: opportunities and challenges for drug development | Nature Reviews Drug Discovery
  7. Isoflavones impair response to anti-PD1 therapy in murine breast cancer models, irrespective of dietary fiber and fecal short chain fatty acid levels - PMC

Original Source(s)

Isoflavones impair anti-PD1 efficacy in breast cancer, regardless of dietary fiber or fecal short-chain fatty acid levels

  • by Fabia de Oliveira Andrade, Kerrie B. Bouker, Melike Ozgul-Onal, Lu Jin, Idalia Cruz, William Helferich, Audrey Gao, Karla Andrade de Oliveira, Vivek Verma, Christopher Staley, Patricia L. Foley, Leena Hilakivi-Clarke

  • July 6, 2026

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