Can Dendritic Cells Improve ERBB2 Breast Cancer Outcomes?

TOPLINE:

For patients with early-stage ERBB2 (formerly HER2)–positive breast cancer, injections of increasing doses of autologous conventional type 1 dendritic cells (cDC1) combined with ERBB2-targeted antibodies demonstrate safety and effectiveness in enhancing immune response. The higher dose (100 million cells) shows enhanced immune effector recruitment and significant tumor regression before chemotherapy initiation.

METHODOLOGY:

• ERBB2-positive breast cancer survival has improved with anti-ERBB2 antibodies trastuzumab and pertuzumab, but for a pathologic complete response, chemotherapy remains necessary, which comes with significant toxic effects.
• A phase 1 nonrandomized clinical trial enrolled 12 patients with early-stage ERBB2-positive breast cancer at Moffitt Cancer Center in Tampa, Florida, from October 2021 to October 2022.
• Participants received intratumoral (IT) cDC1 injections weekly for 6 weeks at two dose levels (50 million cells for dose level 1 and 100 million cells for dose level 2), with six patients in each group.
• Starting from day 1 of the cDC1 injections, treatment included trastuzumab (8 mg/kg loading dose, then 6 mg/kg) and pertuzumab (840 mg loading dose, then 420 mg) administered intravenously every 3 weeks for six cycles, followed by paclitaxel (80 mg/m²) weekly for 12 weeks and surgery with lumpectomy or mastectomy.
• Primary outcomes measured safety and immune response of increasing doses of cDC1 combined with anti-ERBB2 antibodies before neoadjuvant chemotherapy; secondary outcomes assessed antitumor efficacy through breast MRI and residual cancer burden at surgery.

TAKEAWAY:

• IT delivery of ERBB2 cDC1 was safe and not associated with any dose-limiting toxic effects. The most frequent adverse events attributed to cDC1 were grade 1 to 2 chills (50%), fatigue (41.7%), headache (33%), and injection site reactions (33%).
• Dose level 2 showed enhanced recruitment of adaptive CD3, CD4, and CD8 T cells and B cells within the tumor microenvironment (TME), along with increased innate gamma delta T cells and natural killer T cells.
• Breast MRI revealed nine objective responses, including six partial responses and three complete responses, with three cases of stable disease.
• Following surgery, 7 of 12 patients (58%) achieved a pathologic complete response, including all three hormone receptor–negative patients and four of the nine hormone receptor–positive patients.

IN PRACTICE:

“Overall, the clinical data shown here demonstrate the effects of combining ERBB2 antibodies with IT [intratumoral] delivery of targeted cDC1 to enhance immune cell infiltration within the TME [tumor microenvironment] and subsequently induce tumor regression before chemotherapy,” wrote the authors, who noted they will be testing the higher dose for an ongoing phase 2 trial with an additional 41 patients.

SOURCE:

The study was led by Hyo S. Han, MD, of H. Lee Moffitt Cancer Center and Research Institute in Tampa, Florida. It was published online on December 5, 2024, in JAMA Oncology.

LIMITATIONS:

Because only two dose levels of cDC1 were tested, it remains unclear whether higher doses or different administration schedules could further enhance immune response. Additionally, the nonrandomized design prevents definitive conclusions about whether the clinical benefits were solely from the anti-ERBB2 antibodies. The small sample size also makes it difficult to determine if the pathologic complete responses were primarily due to the 12 weeks of trastuzumab/pertuzumab/paclitaxel treatment.

DISCLOSURES:

This study was funded by the Moffitt Breast Cancer Research Fund, Shula Fund, and Pennies in Action. Several authors reported research support and personal and consulting fees from US funding agencies and multiple pharmaceutical companies outside of the submitted work, as well as related intellectual property and patents.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.