Immunotherapy

This short podcast series is directly focused on cancer immunotherapy. Episodes cover where immunotherapies came from, different types of immunotherapies, patient experience, and the future of immunotherapy research. It is a strong overview resource for visitors who want the topic explained in audio form.

Dr. Diane Reidy-Lagunes speaks with medical oncologist and scientist Jedd Wolchok and cancer survivor Grace Dunn about the role of immunotherapy in cancer care. The episode is evidence-based, patient-oriented, and useful as a high-level introduction to immunology as a cancer treatment approach.

The Immunobuddies is a dedicated immunotherapy podcast hosted by oncology clinicians. It covers practical questions about immunotherapy, immune-related adverse events, acute presentations, patient experience, and evolving treatment practice.

This CancerCast episode explains immunotherapy as a cancer treatment that helps the immune system fight cancer. Dr. Jedd Wolchok discusses different types of immunotherapy and how they may be used in multiple cancer settings.

The Immuno-Oncology Clinical Network highlights Immunobuddies patient-facing episodes, including an episode on fundamentals of immunotherapy. The patient miniseries covers questions such as what immunotherapy is, common side effects, adjuvant treatment, diet, and exercise.

i-MPACT focuses on improving care for patients treated with immunotherapy and understanding immune-related adverse events. It is more clinician-facing than a basic patient overview, but it is highly relevant to immunotherapy monitoring and toxicity management.

This Cancer Advances episode discusses the Cleveland Clinic Cellular and Immunotherapy Service and the growing use of immune effector cell therapies such as CAR-T therapy and bispecific antibodies. It is especially useful for understanding how hospitals organize care around complex immunotherapy treatments and side effects.

Overview

This episode of The Breastcancer.org Podcast delves into pioneering research on cancer vaccines for breast cancer, spotlighting a remarkable 20-year follow-up of a clinical trial involving seven patients with metastatic HER2-positive breast cancer. Dr. Zachary Hartman, associate professor at Duke University School of Medicine, shares detailed insights into the original vaccine trial, the discovery of persistent immune memory cells marked by CD27, and ongoing efforts to enhance vaccine efficacy and extend their application to other breast cancer subtypes.

The Original HER2 Vaccine Trial and Immune Memory Discovery

Dr. Hartman describes the initial clinical trial conducted around 2000-2001, which targeted the HER2 protein—a protein amplified in approximately 15-20% of breast cancers. The vaccine strategy involved collecting patients' immune cells through apheresis, educating these cells to recognize HER2 peptides and proteins using adjuvants, and reinfusing them to stimulate an immune response against the cancer.

Despite the small number of participants, the trial was safe and showed promising immune responses. Follow-up studies in 2006 found that all patients were doing well and retained HER2-specific immune responses. In the recent follow-up starting in 2018, five of the original patients provided blood samples, revealing that over 20 years later, these individuals still exhibited robust HER2-specific immune responses.

A key finding was that these immune responses were characterized by CD4 T cells expressing the CD27 marker, which is associated with immune memory. CD27-positive cells represent a population of memory T cells that can persist long-term and rapidly respond upon re-exposure to the antigen. This suggests a durable immune memory that may contribute to long-term cancer control in these patients.

Mechanistic Insights and Preclinical Enhancements Using CD27 Agonists

Building on the discovery of CD27-positive immune memory cells, Dr. Hartman’s team explored the use of a CD27 agonist compound to stimulate these cells further. In preclinical mouse studies, combining the vaccine with a CD27 agonist significantly enhanced immune responses, with memory responses lasting the equivalent of over 30 human years. This approach aims to "supercharge" the immune system’s ability to recognize and control cancer long-term.

The research highlights the importance of memory T cells in sustaining anti-tumor immunity and suggests that activating CD27 pathways could be a critical strategy to improve vaccine effectiveness.

Combining Vaccines with Other Immunotherapies and Standard Treatments

The podcast discusses how cancer vaccines might be combined with other immunotherapies, such as checkpoint inhibitors and antibody-drug conjugates, to further boost immune responses. Dr. Hartman notes that while vaccines alone have not yet become standard cancer treatments, their strong safety profile makes them attractive candidates to complement existing therapies.

For HER2-positive breast cancer, standard treatments include antibodies like trastuzumab (Herceptin) and pertuzumab (Perjeta), often combined with chemotherapy. The vaccine trials have generally been conducted in patients with advanced metastatic disease, where treatment options are limited. Dr. Hartman emphasizes the potential to move vaccines earlier in the treatment timeline to improve outcomes, leveraging their favorable safety compared to chemotherapy and some immunotherapies that can cause significant side effects.

Expanding Vaccine Targets Beyond HER2-Positive Breast Cancer

Recognizing that HER2-positive breast cancer represents a minority of cases, Dr. Hartman and colleagues are developing vaccines targeting other breast cancer subtypes:

• Hormone Receptor-Positive Breast Cancer: This subtype, driven by estrogen receptor (ER) signaling, is the most common form of breast cancer. Current treatments involve endocrine therapies that block estrogen signaling, but resistance often develops through mutations in the estrogen receptor. Dr. Hartman’s team is exploring vaccines targeting estrogen receptor peptides and specific mutations that drive resistance, aiming to train the immune system to recognize and eliminate mutated receptors before clinical resistance emerges.
• Triple-Negative Breast Cancer (TNBC): TNBC lacks HER2 and hormone receptors, making it challenging to target. The research is investigating proteins such as TROP2, which is highly expressed in TNBC and is the target of antibody-drug conjugates currently used in clinical practice. Additionally, mutational patterns like p53 and BRCA mutations are being studied as potential vaccine targets to prevent cancer development or improve treatment responses.
• Genetically Inherited Cancers: For patients with inherited mutations such as BRCA1 and BRCA2, which predispose to breast and ovarian cancers, vaccines targeting multiple proteins and mutated antigens are under investigation. These vaccines aim to prevent cancer onset in high-risk individuals, offering a potential alternative to preventive surgeries.

Challenges in Cancer Vaccine Development

The podcast addresses several challenges faced in cancer vaccine research:

• Small Trial Sizes and Recruitment Difficulties: Many vaccine trials involve small patient numbers, making it difficult to generalize results. Recruitment can be challenging due to the availability of multiple treatment options.
• Complexity of Personalized Vaccines: Early vaccine approaches involved harvesting and culturing patients’ own immune cells, which is complex and limits scalability and accessibility, especially in smaller or rural clinics.
• Funding Constraints: Clinical trials are expensive, and recent reductions in funding have slowed progress in advancing vaccine research.

Dr. Hartman advocates for developing simpler, broadly applicable vaccines that can be administered easily in routine clinical settings, potentially improving accessibility and impact.

Safety Profile and Side Effects

The episode highlights the favorable safety profile of cancer vaccines, especially compared to chemotherapy and immune checkpoint inhibitors, which can cause significant autoimmune side effects. Since vaccines target self-proteins like HER2, there is a theoretical risk of autoimmunity, but long-term follow-up of the original trial participants has not revealed major adverse effects.

Dr. Hartman notes that combining vaccines with other immune-activating therapies will require careful monitoring in clinical trials to manage potential side effects. However, vaccine administration is typically limited to a short series of injections, contrasting with prolonged treatments like chemotherapy or checkpoint inhibitors, which may reduce cumulative toxicity.

Future Directions and Clinical Translation

Looking ahead, Dr. Hartman and his team plan to initiate new clinical trials incorporating CD27 agonists and other immune stimulants to enhance vaccine efficacy. They are also exploring how vaccines might synergize with approved antibody-drug conjugates and checkpoint inhibitors to improve outcomes.

The goal is to develop safe, effective vaccines that provide long-term tumor control and can be adapted to various breast cancer subtypes and potentially other cancers. Dr. Hartman expresses hope that within the next decade, progress in breast cancer vaccine research will expand and inform treatments for other cancer types.

Summary of Key Points

• The original HER2 vaccine trial showed long-lasting immune memory in metastatic breast cancer patients, with CD27-positive CD4 T cells playing a central role.
• Preclinical studies demonstrate that CD27 agonists can enhance vaccine-induced immune responses, potentially improving long-term tumor control.
• Combining vaccines with other immunotherapies and standard treatments may increase effectiveness, especially if vaccines are moved earlier in the treatment course.
• Research is expanding to develop vaccines targeting hormone receptor-positive and triple-negative breast cancers, as well as genetically inherited cancer risks.
• Challenges include small trial sizes, recruitment, manufacturing complexity, and funding limitations.
• Cancer vaccines have a favorable safety profile compared to many current therapies, but combination approaches require careful evaluation.
• Future clinical trials aim to translate these findings into broadly applicable, effective cancer vaccines.

Source Information

This content is based on a 30-minute podcast episode from The Breastcancer.org Podcast, featuring an interview with Dr. Zachary Hartman, associate professor of surgery, integrative immunology, and pathology at Duke University School of Medicine. The episode was released in 2024 and discusses both historical and current research on cancer vaccines in breast cancer, with a focus on immunological mechanisms and translational research efforts. The transcript provided forms the basis of this detailed description, reflecting the specific claims, research context, and expert perspectives shared during the interview.

This episode discusses neoantigens, which are tumor-specific markers that may be targeted by personalized immunotherapies. It is a general-interest science episode that helps explain one direction of modern cancer immunotherapy research.

This episode discusses research into why cancer immunotherapy can fail, including T-cell exhaustion and possible paths toward improving treatment response. It is a deeper science-facing episode suited to visitors who want to understand limitations and future directions.

Immunotherapy Talks with ACIR is a research-facing podcast from Accelerating Cancer Immunotherapy Research. It is useful for professional or technically curious listeners who want discussion of immunotherapy studies and mechanisms rather than basic patient education.