Background. In this phase II clinical trial, we evaluated the efficacy of the non-anthracycline combination of carboplatin and nab-paclitaxel in early stage triple negative breast cancer (TNBC). Patients and Methods. Patients with newly diagnosed stage II-III TNBC (N=69) were treated with neoadjuvant carboplatin (AUC 6) every 28 days x 4 plus nab-paclitaxel (100 mg/m 2) weekly for 16 weeks. Pathological complete response (pCR) and residual cancer burden (RCB) were analyzed with germline mutation status, tumor infiltrating lymphocytes (TILs), TNBC molecular subtype, and GeparSixto immune signature (GSIS). Results. Sixty-seven patients were evaluable for safety and response. Fifty-three (79%) patients experienced grade 3/4 adverse events (AEs), including Grade 3 anemia (43%), neutropenia (39%), leukopenia (15%), thrombocytopenia (12%), fatigue (7%), peripheral neuropathy (7%), neutropenia (16%), and leukopenia (1%). Twenty-four patients (35%) had at least one dose delay and 50 patients (72%) required dose reduction. Sixty-three (94%) patients completed scheduled treatment. The responses were 32/67 (48%) pCR (RCB 0), 10/67 (15%) RCB I, 19/67 (28%) RCB II, 5/67 (7%) RCB III, and 1/67 (2%) progressed and had no surgery. Univariate analysis showed GSIS "immune-hot" and DNA repair defect (DRD) were associated with higher pCR with odds ratio of 4.62 (P=0.005) and 4.76 (P=0.03) respectively, and with RCB 0/I vs. RCB II/III with odds ratio 4.80 (P=0.01). "Immune-hot" GSIS was highly correlated with DRD status (P=0.03), TILs level (P<0.001), and TNBC molecular subtype (P<0.001). After adjusting for age, race, stage, and grade, GSIS remained associated with higher pCR and RCB class 0/I vs. II/III with odds ratio 7.19 (95% CI 2.01-25.68, P=0.002) and 8.95 (95%. CI 2.09-38.23, P=0.003), respectively. Conclusions. The combination of carboplatin and nabpaclitaxel for early stage high risk TNBC showed manageable toxicity and encouraging anti-tumor activity. GSIS "immune-hot" signature is associated with higher pCR rate and RCB class 0/1. This study provides additional rationale for using non-anthracycline platinum-based therapy for future neoadjuvant trials in early stage TNBCs. The Oncologist 2020;9999:• • Implications for Practice: Platinum is an important neoadjuvant chemotherapy agent for treatment of early stage triple negative breast cancer (TNBC). In this study, carboplatin and nab-paclitaxel were well tolerated and highly effective in TNBC, resulting in pathological complete response of 48%. In univariate and multivariate analyses adjusting for age, race, tumor stage and grade, "immune-hot" GeparSixto Immune Signature (GSIS) and DNA repair defect were associated with higher pCR and residual cancer burden class 0/1. The association of GSIS "immune-hot" signature with higher pCR holds promise for "de-escalating" neoadjuvant chemotherapy for patients with early stage TNBC. Although GSIS is not routinely used in clinic, further development of this immune signature into a clinically applicable assay is indicated.

Immunohistochemically ER-positive HER2-negative (ER+HER2−) breast cancers are classified clinically as Luminal-type. We showed previously that molecular subtyping using the 80-gene signature (80-GS) reclassified a subset of ER+HER2− tumors to molecular Basal-type. We report here that molecular reclassification is associated with expression of dominant-negative ER variants and evaluate response to neoadjuvant therapy and outcome in the prospective neoadjuvant NBRST study (NCT01479101). The 80-GS reclassified 91 of 694 (13.1%) immunohistochemically Luminal-type tumors to molecular Basal-type. Importantly, all 91 discordant tumors were classified as high-risk, whereas only 66.9% of ER+/Luminal-type tumors were classified at high-risk for disease recurrence (i.e., Luminal B) ( P < 0.001). ER variant mRNA (ER∆3, ER∆7, and ERα-36) analysis performed on 84 ER+/Basal tumors and 48 ER+/Luminal B control tumors revealed that total ER mRNA was significantly lower in ER+/Basal tumors. The relative expression of ER∆7/total ER was significantly higher in ER+/Basal tumors compared to ER+/Luminal B tumors ( P < 0.001). ER+/Basal patients had similar pathological complete response (pCR) rates following neoadjuvant chemotherapy as ER−/Basal patients (34.3 vs. 37.6%), and much higher than ER+/Luminal A or B patients (2.3 and 5.8%, respectively). Furthermore, 3-year distant metastasis-free interval (DMFI) for ER+/Basal patients was 65.8%, significantly lower than 96.3 and 88.9% for ER+/Luminal A and B patients, respectively, (log-rank P < 0.001). Significantly lower total ER mRNA and increased relative ER∆7 dominant-negative variant expression provides a rationale why ER+/Basal breast cancers are molecularly ER-negative. Identification of this substantial subset of patients is clinically relevant because of the higher pCR rate to neoadjuvant chemotherapy and correlation with clinical outcome.

Background: MammaPrint (MP) is used to identify breast cancer (BC) patients who can safely forego adjuvant chemotherapy. MP combined with the BluePrint (BP) molecular subtyping signature identifies BC subtypes with distinct therapeutic response rates and survival outcomes. In the Neoadjuvant Breast Symphony Trial (NBRST), MP and BP (MP/BP) predicted rates of pathologic complete response to neoadjuvant chemotherapy (NCT) and partial response to neoadjuvant endocrine therapy (NET). Here, we report 5-year overall survival (OS) and distant metastasis-free survival (DMFS) in patients from the NBRST registry according to MP/BP molecular classification. Methods: The NBRST trial (NCT01479101) prospectively enrolled 1072 patients from 2011 to 2014, who received MP and BP testing. Patients were assigned to receive NCT or NET according to NCCN guidelines and consented to 5 years post-surgery follow-up (FU). Clinical outcomes were available for 913 patients from 67 US institutions. Median FU for OS and DMFS was 5 and 4.6 years, respectively. Tumors classified by MP as High Risk (HR) or Low Risk (LR) were further stratified into four molecular subtypes by BP: Luminal A, Luminal B, HER2, and Basal. Differences in OS and DMFS at 3 and 5 years were assessed by Kaplan Meier analysis and log-rank test. Results: MP results from neoadjuvant patients (N=913) classified 16% of tumors as MP LR and 84% as MP HR. MP and BP classified 15.7% (143/913) of tumors as Luminal A, 32.5% (297/913) as Luminal B, 17.1% (156/913) as HER2, and 34.7% (317/913) as Basal. The 5-year OS and DMFS probabilities were significantly lower in HR compared to LR patients (p &lt; 0.001 for OS and DMFS), and lowest in Basal and Luminal B compared to Luminal A and HER2 subtypes (p &lt; 0.001 for OS and DMFS). Most DMFS events in BP Basal tumors occurred within the first 3 years. Of 841 patients that received NCT with or without HER2-targeted therapy, 12.2% (103/841) were LR and 87.8% (738/841) were HR. MP and BP classified 11.9% (100/841) of these patients as Luminal A, 32.6% (274/841) as Luminal B, 8.3% (154/841) as HER2 subtype, and 37.2% (313/841) as Basal. The 5-year OS and DMFS probabilities were lowest in HR, Basal or Luminal B patients (p &lt; 0.001). In 59 patients who received NET alone, 5-year OS and DMFS were significantly worse in HR patients that had Luminal B or HER2 tumors compared to LR Luminal A patients. In the 39 patients with Luminal A tumors, response to NET at the time of surgery was: 46.2% partial response, 41.0% stable disease, 5.1% progressive disease, 2.6% not reported. Five year DMFS in patients with Luminal A tumors treated with NCT or NET was not significantly different (p=0.67).Conclusions: MammaPrint remained prognostic in BC patients undergoing neoadjuvant therapy. Long -term prognosis was excellent in LR groups who received NCT or NET alone. MP and BP can accurately classify patients into specific subtypes with distinct OS and DMFS outcomes at five years, with BP Basals having the worst outcomes, followed by Luminal B, HER2, and Luminal A subtypes. BP Basal patients had the highest frequency of events within the first 3 years post-surgery, suggesting a genomic risk timeline distinct from other BP subtypes and a potential benefit from a secondary therapeutic immediately post-surgery. Additionally, Luminal A patients had a very low risk of progressive disease while on NET alone prior to surgery, with similar DMFS outcomes to Luminal A-types who received NCT. Number of patientsObserved events% at 5 year (95% CI)p-valueAll patients - MammaPrint Risk GroupOS913134p&lt;0.001Low Risk146794.7 (88.4-97.6)High Risk76712781.1 (77.7-84.0)DMFS913182p&lt;0.001Low Risk1461191.2 (84.2-95.2)High Risk76717175.5 (71.9-78.7)All patients - MammaPrint + BluePrint SubtypeOS913134p&lt;0.001Luminal A143794.6 (88.3-97.6)Luminal B2974484.5 (80.0-88.7)Basal3177472.2 (66.2-77.3)HER2156993.4 (87.1-96.7)DMFS913182p&lt;0.001Luminal A1431191.1 (82.1-94.3)Luminal B2976975.2 (68.0-80.4)Basal3178570.4 (64.6-75.5)HER21561787.2 (79.7-92.0)NCT patients - MammaPrint Risk GroupOS841121p&lt;0.001Low Risk103397.4 (90.1-99.4)High Risk73811881.7 (78.3-84.7)DMFS841167p&lt;0.001Low Risk103792.6 (84.1-96.6)High Risk73816076.2 (72.5-79.4)NCT patients - MammaPrint + BluePrint SubtypeOS841121p&lt;0.001Luminal A100395.5 (86.2-98.6)Luminal B2743978.9 (71.7-84.5)Basal3137168.7 (57.9-77.2)HER2154892.8 (85.9-96.4)DMFS841167p&lt;0.001Luminal A100792.4 (83.8-96.5)Luminal B2746375.7 (65.6-76.5)Basal3138171.4 (65.6-76.5)HER21541687.7 (80.2-92.5)NET alone patients - MammaPrintOS597p=0.01Low Risk39293.0 (74.6-98.2)High Risk20580.0 (55.1-92.0)DMFS598p=0.003Low Risk39293.0 (74.6-98.2)High Risk20674.7 (49.4-88.6)NET alone patients - MammaPrint +BluePrint SubtypeOS597p=0.008Luminal A39293.0 (74.6-98.2)Luminal B18483.3 (56.8-94.3)Basal00N/AHER221N/ADMFS598p=0.005Luminal A39293.0 (74.6-98.2)Luminal B18577.4 (50.3-90.9)Basal00N/AHER221N/A Citation Format: Pat Whitworth, James V Pellicane, Jr., Paul Baron, Peter Beitsch, Laura Lee, Michael Rotkis, Angela Mislowsky, Carrie Dul, Charles Nash, Bichlien Nguyen, Mary Murray, Paul Richards, Mark Gittleman, Stephanie Akbari, Shiyu Wang, Erin B Yoder, Andrea Menicucci, Lisa Blumencranz, William Audeh, NBRST Investigators Group. 5-year outcomes in the NBRST trial: Preoperative MammaPrint and BluePrint breast cancer subtype is associated with neoadjuvant treatment response and survival [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PD9-01.

This substudy showed that NAT significantly altered the genomic signature of the patient's breast cancer compared with the patient's pretreatment genomic profile. These alterations occurred in a subtype-dependent manner, suggesting that NAT may have either eliminated the most susceptible tumor subclone, leaving the treatment resistant clone with a different genetic signature, or altered molecular characteristics of the original cancer.

PURPOSE The 80-gene molecular subtyping signature (80-GS) reclassifies a proportion of immunohistochemistry (IHC)-defined luminal breast cancers (estrogen receptor–positive [ER+], human epidermal growth factor receptor 2–negative [HER2–]) as Basal-Type. We report the association of 80-GS reclassification with neoadjuvant treatment response and 5-year outcome in patients with breast cancer. METHODS Neoadjuvant Breast Registry Symphony Trial (NBRST; NCT01479101 ) is an observational, prospective study that included 1,069 patients with early-stage breast cancer age 18-90 years who received neoadjuvant therapy. Pathologic complete response (pCR) and 5-year distant metastasis-free survival (DMFS) and overall survival (OS) were assessed in 477 patients with IHC-defined ER+, HER2– tumors and in a reference group of 229 patients with IHC-defined triple-negative breast cancer (TNBC). RESULTS 80-GS reclassified 15% of ER+, HER2– tumors (n = 73) as Basal-Type (ER+/Basal), which had similar pCR compared with TNBC/Basal tumors (34% v 38%; P = .52), and significantly higher pCR than ER+/Luminal A (2%; P < .001) and ER+/Luminal B (6%; P < .001) tumors. The 5-year DMFS (%, [95% CI]) was significantly lower for patients with ER+/Basal tumors (66% [52.6 to 77.3]), compared with those with ER+/Luminal A tumors (92.3% [85.2 to 96.1]) and ER+/Luminal B tumors (73.5% [44.5 to 79.3]). Importantly, patients with ER+/Basal or TNBC/Basal tumors that had a pCR exhibited significantly improved DMFS and OS compared with those with residual disease. By contrast, patients with ER+/Luminal B tumors had comparable 5-year DMFS and OS whether or not they achieved pCR. CONCLUSION Significant differences in chemosensitivity and 5-year outcome suggest patients with ER+/Basal molecular subtype may benefit from neoadjuvant regimens optimized for patients with TNBC/Basal tumors compared with patients with ER+/Luminal subtype. These data highlight the importance of identifying this subset of patients to improve treatment planning and long-term survival.