Dana-Farber researchers to present findings at San Antonio Breast Cancer Symposium 3 December

Researchers from Dana-Farber Cancer Institute will present more than 30 research studies at the 45th annual San Antonio Breast Cancer Symposium, December 6 -10, 2022. The San Antonio Breast Cancer Symposium is the world’s most comprehensive academic breast cancer meeting, attracting thousands of breast cancer professionals from around the world.

Dana-Farber faculty will be leading and participating in spotlight sessions, debates, posters, lectures, and educational sessions covering clinical, translational and basic research at this year’s conference.

Select presentations by Dana-Farber researchers include:

Pregnancy Outcome and Safety of Interrupting Therapy for women with endocrine responsIVE breast cancer: Primary Results from the POSITIVE Trial (GS4-09)

Presenter: Ann Partridge, MD, MPH

Date & Time: ***Results to be presented at Thursday, December 8 SABCS press conference @ 7:30AM CT

Ann Partridge, MD will present results from the POSITIVE trial, a prospective study which investigates if temporary interruption of endocrine therapy with the goal to permit pregnancy, is associated with a higher risk of breast cancer recurrence in young women with hormone receptor-positive early breast cancer.

Palbociclib After CDK4/6i and Endocrine Therapy (PACE): A Randomized Phase II Study of Fulvestrant, Palbociclib, and Avelumab for Endocrine Pre-treated ER+/HER2- Metastatic Breast Cancer (GS3-06)

Presenter: Erica Mayer, MD, MPH

Date & Time: Thursday, December 8, 9:45 am

Erica Mayer, MD will present findings from the Palbociclib After CDK4/6i and Endocrine Therapy (PACE) phase 2 clinical trial. In patients with metastatic estrogen receptor-positive, HER2-negative breast cancer that continued to progress after treatment with a CDK4/6 inhibitor and aromatase inhibitor, treatment with palbociclib (a CDK4/6 inhibitor) and the drug fulvestrant did not lengthen progression-free survival – the period in which patients are alive without a worsening of their cancer – compared to fulvestrant alone, results from the phase II PACE trial show. However, patients who received the immunotherapy drug avelumab in addition to palbociclib and fulvestrant did have an improved progression-free survival. In the trial, which included 220 patients, the median progression-free survival for those treated with fulvestrant alone was 4.8 months, while it was 4.6 months for those treated with fulvestrant and palbociclib, and 8.1 months for those treated with the three-drug regimen – an encouraging sign for this population of patients, investigators say.

Clonal evolution and mechanisms of acquired resistance to CDK4/6 inhibitors in ER-wild type and ER-mutant breast cancer (GS3-07)

Presenter: Cristina Guarducci, PhD Senior author: Rinath Jeselshon, MD

Date & Time: Thursday, December 8, 10:00 am

For patients with metastatic estrogen receptor-positive breast cancer, adding a third drug to the standard combination of a CDK4/6 inhibitor and hormone therapy early during treatment can potentially slow the development of drug resistance and prolong the benefits of the treatment, a new study shows. The results were obtained by tracking clonal evolution in lab-grown breast cancer cells – some with normal estrogen receptors, some with receptors carrying a Y537S mutation – during treatment with palbociclib or abemaciclib, both CDK4/6 inhibitors. The cells were treated with increasing doses of these drugs until they became drug-resistant. Researchers also compared the clonal evolution of the estrogen receptor-mutated, CDK4/6 inhibitor-resistant cells to the evolution of metastatic estrogen receptor-mutated cells in animal models. They found that development of resistance to CDK4/6 inhibitors stemmed from a surge in a subset of tumor cells that existed prior to treatment and that the Y537S mutation affects the development of resistance to palbociclib but less so to abemaciclib. They also show that the clonal selection and evolution is different with palbociclib versus abemaciclib, highlighting the differences between these two drugs. These findings suggest that supplementing a CDK4/6 inhibitor and hormonal therapy with a third drug early in treatment can delay the process by which cells resistant to CDK4/6 inhibitors become dominant and can extend the response to treatment.

Adjuvant Trastuzumab Emtansine Versus Paclitaxel plus Trastuzumab for Stage I HER2+ Breast Cancer: 5-year results and correlative analyses from ATEMPT

Presenter: Paolo Tarantino, MD

Date & Time: Friday, December 9th

Results of a follow-up study support earlier findings about the effectiveness of the drug trastuzumab emtansine (T-DM1) as adjuvant therapy for patients with stage I HER2-positive breast cancer. The primary findings of the ATEMPT trial found that 97.8% of patients treated with T-DM1 – an antibody drug conjugate – were alive and free of invasive breast cancer three years after treatment. The new results show that five years after treatment, 97% were alive and free from invasive disease, and 98.3% had no recurrence of their cancer. Researchers also analyzed tumor tissue from 187 trial participants with the novel HER2DX genomic tool, which identified a subset of tumors with significantly higher risk of recurrence, paving the way for an increase in the precision of adjuvant treatments for patients with small HER-positive breast cancer.

Adjuvant Paclitaxel and Trastuzumab Trial (APT) for Node-Negative, Human Epidermal Growth Factor Receptor 2-Positive (HER2+) Breast Cancer: final 10-year results and correlative analyses

Presenter: Sara Tolaney, MD, MPH

Date & Time: Friday, December 9th 7AM

The Adjuvant Paclitaxel and Trastuzumab (APT) trial evaluated the activity of adjuvant paclitaxel and trastuzumab among patients with small, node negative HER2-positive breast cancer. Earlier findings from the study have reshaped clinical practice, with the APT regimen currently considered a treatment standard worldwide. In this end-of-study analysis being presented at the San Antonio Breast Cancer Symposium, researchers report that after 10 years of follow-up, adjuvant paclitaxel and trastuzumab confirmed excellent long-term outcomes for small, node-negative HER2-positive breast cancer, with 96.3% of the patients being free from tumor recurrence at 10 years. Additionally, the novel HER2DX genomic tool was applied in tumors from 284 trial participants and was found to be significantly associated with the risk of recurrence.

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