ASCO 2026 TNBC Deep Dive: Breast Cancer Experts Preview Practice-Informing Studies

As conversations continue around the 2026 ASCO Annual Meeting, several triple-negative breast cancer (TNBC) presentations are among the most anticipated datasets. Read on for exclusive insights from the following breast cancer experts:

• VK Gadi, MD, PhD, deputy director of the University of Illinois (UI) Cancer Center and a medical oncologist at UI Health, as well as an assistant professor of clinical medicine and director of Medical Oncology in the Division of Hematology and Oncology at the UI College of Medicine in Chicago
• Erika Hamilton, MD, FASCO, the Late Phase chief development officer and director of Breast Cancer Research at Sarah Cannon Research Institute in Nashville, Tennessee
• Kevin Kalinsky, MD, MS, FASCO, professor and director of the Division of Medical Oncology in the Department of Hematology and Medical Oncology at the Emory University School of Medicine, as well as the Louisa and Rand Glenn Family Chair in Breast Cancer Research and the director of the Glenn Family Breast Center at the Winship Cancer Institute of Emory University in Atlanta, Georgia
• Alexis LeVee, MD, a breast medical oncologist at UCLA Health in Santa Monica, California
• Jane L. Meisel, MD, FASCO, a professor and co-director of Breast Medical Oncology in the Department of Hematology and Medical Oncology, as well as a professor in the Department of Gynecology & Obstetrics at the Emory University School of Medicine

Looking for key abstracts to watch in hormone receptor–positive or HER2-positive breast cancer? Check our additional ASCO 2026 breast cancer preview here.

Neoadjuvant pembrolizumab or placebo plus chemotherapy followed by adjuvant pembrolizumab or placebo for high-risk early-stage TNBC: Final analysis results from the phase 3 KEYNOTE-522 study

Presentation time: May 30, 2026, 3:27 pm CT

Hamilton: The phase 3 KEYNOTE-522 trial [NCT03036488] regimen has emerged as our standard treatment for higher-risk TNBC. The 5-year overall survival [OS] rate was improved by 4.9%, and there was a 9% improvement in disease-free survival [in the pembrolizumab (Keytruda) arm vs the placebo arm].¹ This last disclosure will tell us how much benefit patients derive from the addition of pembrolizumab to chemotherapy and give us a new current benchmark for cure rates with modern chemoimmunotherapy in advanced triple-negative disease.

Kalinksy: KEYNOTE-522 was the neoadjuvant adjuvant study that investigated and led to [the FDA approval of] 1 year of pembrolizumab for patients with early stage II to III disease starting in the neoadjuvant setting along with chemotherapy, followed by surgery and continuation of pembrolizumab [as adjuvant therapy]. We already know there’s an improvement in survival, and we’ll see with additional follow-up what that looks like.

ASCENT-04: Analysis of efficacy by biomarker subgroups with sacituzumab govitecan (SG) + pembrolizumab (pembro) vs chemotherapy (chemo) + pembro in participants (pts) with previously untreated PD-L1+ metastatic triple-negative breast cancer (mTNBC).

Presentation time: May 31, 2026, 11:30 am CT

ASCENT-03: Efficacy by biomarker subgroup with sacituzumab govitecan (SG) vs chemotherapy (chemo) in participants (pts) with previously untreated advanced triple-negative breast cancer (TNBC) who are not candidates for PD-(L)1 inhibitors (PD-[L]1i).

Presentation time: May 31, 2026, 11:36 am CT

LeVee: There are analyses of the ASCENT trials and how biomarkers could predict response with sacituzumab govitecan-hziy [Trodelvy] with or without pembrolizumab. I am looking to see whether we could use biomarkers to predict which patients would benefit from those therapies.

Progression-free survival after next line of treatment (PFS2) and subsequent therapies (subs tx) in the ASCENT-04 study of participants (pts) with previously untreated PD-L1+ metastatic triple-negative breast cancer (mTNBC) treated with sacituzumab govitecan (SG) plus pembrolizumab (pembro) vs chemotherapy (chemo) plus pembro

Presentation time: June 2, 2026, 9:45 am CT

Progression-free survival after next line of treatment (PFS2) and subsequent therapies (subs tx) in the ASCENT-03 study of participants (pts) with previously untreated metastatic triple-negative breast cancer (mTNBC) treated with sacituzumab govitecan (SG) vs chemotherapy (chemo).

Presentation time: June 2, 2026, 9:57 am CT

Meisel: We know from both studies that using sacituzumab govitecan instead of chemotherapy showed benefit in these populations in terms of progression-free survival [PFS]. But if you look at what [therapies these patients] start next, and how long they [respond] in that aggregate time point from starting sacituzumab govitecan to progression on the second subsequent line, do they do better if they start with sacituzumab govitecan, or is it okay to get the sacituzumab govitecan later? Those data will help us from a real-world standpoint because that drug is wonderful for many patients, but it is associated with certain adverse effects that, especially for patients with newly diagnosed TNBC, can be challenging. It would be good to know: Do we really need to start all patients on that drug, or could we have the choice to use it in the second-line setting?

Izalontamab brengitecan (iza-bren) versus physician’s choice of chemotherapy in patients with unresectable locally advanced or metastatic triple-negative breast cancer (TNBC): A randomized phase III study

Presentation time: June 2, 2026, 10:45 am CT

Meisel: Izalontamab brengitecan [iza-bren; BL-B01D1] is a first-in-class bispecific antibody-drug conjugate [ADC] that’s being studied in first-line metastatic TNBC. We’ll see some of the first results from this trial, so I’m looking forward to seeing what that shows and whether that drug is as effective as it potentially could be.

Gadi: Bispecific means the drug targets 2 proteins at the same time on the cell surface. In this case, this molecule targets EGFR and HER3, 2 EGFR family members that are often present on lots of cancer cells, including TNBC cells. In addition, [iza-bren] has a topoisomerase-1 [inhibitor] payload. Because of its bispecific nature, you can think of it as almost like a logic gate. When 1 target is present, the molecule may be reasonably effective at finding the target. When the other target is present, [iza-bren] may be reasonably effective. The presence of both targets ensures good binding to that cancer cell. You can get maximal effect to target cells, potentially with minimal off-target toxicity. We’ll see in the data whether that was borne out. [A news release reported that this trial has positive PFS and OS findings] for patients with TNBC in this randomized phase 3 study against physician’s choice of therapy on the other arm.² This is a purely Chinese study. [Iza-bren is being developed by] a Chinese company with a United States presence, SystImmune, and will be their first molecule potentially being filed in the market. I’m not sure what the data will look like, but it’s nice to see a bispecific ADC moving towards translation and potentially commercialization.

References

1. Schmid P, Cortes J, Dent R, et al. Neoadjuvant pembrolizumab or placebo plus chemotherapy followed by adjuvant pembrolizumab or placebo for high-risk early-stage TNBC: overall survival results from the phase III KEYNOTE-522 study. Ann Oncol. 2024;35(suppl 2):S1204-S1205. doi:10.1016/j.annonc.2024.08.2247
2. SystImmune and Bristol Myers Squibb highlight positive phase III interim topline results for izalontamab brengitecan (Iza-bren) in previously treated unresectable locally advanced or metastatic triple-negative breast cancer. News release. February 26, 2026. Accessed May 7, 2026. https://news.bms.com/news/corporate-financial/2026/SystImmune-and-Bristol-Myers-Squibb-Highlight-Positive-Phase-III-Interim-Topline-Results-for-izalontamab-brengitecan-Iza-bren-in-Previously-Treated-Unresectable-Locally-Advanced-or-Metastatic-Triple-Negative-Breast-Cancer/default.aspx