Li, Zhuo

Abstract Background Metaplastic breast cancer (MBC) is a rare and aggressive subtype of breast cancer (BC) defined by presence of both epithelial and mesenchymal components. Most are triple negative but are often chemo-refractory and associated with poor survival outcomes compared to non-metaplastic triple negative BC. Advances in therapy have led to improvements in survival outcomes of patients (pts) with BC over the last decade. Our multicenter retrospective study aims to assess (1) progression free survival (PFS) and overall survival (OS) (2) factors predictive of survival outcomes in MBC pts Methods We performed a retrospective analysis of pts diagnosed with MBC from 1997-2021 at Mayo Clinic (Florida, Arizona and Rochester) under IRB approval. Kaplan-Meier method was used to estimate OS and PFS at 1, 3 and 5 years. Cox regression models were used to examine the association between risk factors and survival outcomes. All tests were two-sided with p value < 0.05 considered statistically significant Results We evaluated 158 pts with MBC. Median age and tumor size was 61 (range: 20-91) years and 2.8 (range: 0.5-21) cm, respectively, with 80% of pts being postmenopausal. At diagnosis, 14.6% of pts had clinical T3/T4 disease, 16.4% were clinically node-positive, and 6.3% (10 pts) had distant metastases (DM). Spindle cell histology was seen in 36 pts. Most MBC pts were triple-negative (68.3%), high grade (77.2%) and high Ki-67 (36/47; 76.5%). Of the 61 pts tested for germline mutation, 8 (13.1%) were positive, with BRCA1/2, PTEN, NBN, CHEK2, and BARD1 mutations. Most pts had lumpectomy (53.8%), followed by simple mastectomy (38.5), and modified radical mastectomy (7.7%). Majority of pts had sentinel lymph node biopsy (71.8%). Adjuvant radiation therapy was performed in 65.6% of pts. Pathologic complete response (pCR) was noted in 4/38 (10.5%) evaluable pts who received neoadjuvant chemotherapy (NACT). Residual cancer burden (RCB) scores of 2 and 3 were seen in 76.2% of evaluable pts. Median follow-up time was 2.2 years (range: 6 days-24.6 years). Overall, 1-, 3-, and 5-year OS was 93.3%, 81.7%, and 76.0%, while PFS was 80.8%, 67.9%, and 60.9%, respectively. The presence of DM at diagnosis [HR 38.55 (11.18, 132.93), p < 0.001] and spindle cell histology (SC) [HR 2.57 (1.19, 5.53), p = 0.02] predicted worse OS in multivariable analysis. Inferior PFS was predicted by DM [HR 18.84 (6.53, 54.35), p < 0.001], SC [HR 2.46 (1.25, 4.86), p = 0.009], and node-positivity at diagnosis [HR 3.65 (1.5, 8.89), p = 0.004]. The 5-year OS and PFS were 22.2% and 0% for DM pts versus 80.0% and 65.6% for non-DM pts. The 5-year OS and PFS were 71.5% and 54.7% for SC pts versus 81% and 66.6% for non-SC pts. 5-year OS and PFS for NACT pts was 67.3% and 52.6% for NACT pts versus 78.2% and 62.8% for non-NACT pts. Age at diagnosis, menopausal status, family history of BC, grade, stage, tumor size, hormone-receptor and HER2 status, and use of NACT were not found to be significantly associated with OS or PFS in multivariate analysis. Conclusion This study is one of the largest and most recent review of institutional experiences with MBC. Overall, OS at 5 years was improved compared to prior older studies of MBC but still remains very low for those with DM, representing an area of unmet clinical need. SC and DM correlated with worse outcomes for both PFS and OS. Additionally, node positivity at diagnosis was a predictor of worse PFS. In contrast, no association was seen between survival and tumor size, stage, hormone receptor-positivity, HER2 receptor-positivity. The low pCR rates following NACT in our study are consistent with reported literature. Further, use of NACT does not impact survival, suggesting pts with resectable disease should proceed with surgery first. Citation Format: Siven Chinniah, Raza Zarrar, Zhuo Li, Kostandinos Sideras, Alvaro Moreno-Aspitia, Saranya Chumsri, Rohit Rao, Sarah McLaughlin, James Jakub, Emmanuel Gabriel, Sanjay Bagaria, Laura Vallow, Santo Maimone, Pooja Advani. Clinical Factors associated with Survival Outcomes in Patients with Metaplastic Breast Cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P3-05-25.

Abstract Background: We previously demonstrated that intrinsic subtypes were associated with prognosis for early recurrence risk in patients (pts) with early-stage HER2-positive (HER2+) BC treated with trastuzumab (H) in the N9831 trial. Here, we evaluated the prognostic value of Intrinsic subtypes and 21-gene assay and the risk of early and late recurrence in the N9831 trial. Methods: NanoString custom code set, which included PAM50 and housekeeping genes, was used to quantify mRNA and generated intrinsic subtypes and risk of recurrence (ROR) score from the N9831 trial in Arms A and C: Arm A chemotherapy alone and arm C concurrent H. Quantitative RT-PCR of 21 genes, calculation of the axis, including estrogen axis (ER, PGR, BCL2, SCUBE2), HER2 axis (GRB7, HER2), proliferation axis (Ki67, STK15, Survivin, CCNB1, MYBL2), invasion axis (MMP11, CTSL2), and recurrence score (RS) risk group assignment (RS group 1 and 2: RS < 31 and RS group 3: RS ≥ 31) were performed using Oncotype DX assay. Cox regression models for RFS were used for analysis. Early recurrence was defined as a recurrence that occurred at ≤ 5 years, and late recurrence was defined as recurrence at > 5 years. Results: A total of 783 patients (Arm A 409 and Arm C 374) were included in this analysis. Using multivariate Cox regression analysis to evaluate the risk of early recurrence in patients who received chemotherapy alone in arm A, both invasion genes (MMP11 HR 1.23, 95%CI 1.05-1.44, p 0.01 and CTSL2 HR 1.36, 95%CI 1.1-1.69, p 0.005) and invasion axis (HR 1.64, 95%CI 1.26-2.13, p < 0.001) were associated with a higher rate of early recurrence. CD68 was associated with improved outcomes (HR 0.56, 95%CI 0.38-0.83, p 0.004). For the risk of early recurrence in patients treated with trastuzumab in arm C, ER (HR 0.85, 95%CI 0.74-0.97, p 0.02), PR (HR 0.78, 95%CI 0.64-0.94, p 0.008), and estrogen axis (HR 0.7, 95%CI 0.57-0.87, p 0.001) were associated with improved outcomes. Invasion axis (HR 1.61, 95%CI 1.08-2.41, p 0.02), Oncotype Dx risk group (3 vs. 1 and 2, HR 8.89, 95%CI 1.27-1124, p 0.02), and basal subtype (HR 2.77, 95%CI 1.1-5.95, p 0.03) were also significantly associated with worse outcomes. For risk of late recurrence, in arm A, ER (HR 1.22, 95%CI 1.04-1.44, p 0.02), PR (1.26, 95%CI 1.05-1.5, p 0.01), and estrogen axis (1.39, 95%CI 1.09-1.77, p 0.008) were associated with worse outcomes. Oncotype Dx risk group (3 vs. 1 and 2, HR 0.4, 95%CI 0.16-0.98, p 0.05) was associated with improved outcomes. However, neither individual gene, axis, nor intrinsic subtypes were associated with the risk of late recurrence in patients treated with trastuzumab. Conclusions: For risks of early recurrence, the invasion genes/axis were associated with increased risks of recurrence in patients with early-stage HER2+ BC regardless of trastuzumab treatment. Among patients treated with trastuzumab, ER genes/axis, Oncotype Dx risk group, and intrinsic subtype were prognostic for risks of recurrence in the first five years. For risks of late recurrence, ER genes/axis and Oncotype Dx risk group were prognostic but only in patients treated with chemotherapy alone. The ER genes/axis were associated with less recurrence in the first five years but worse after five years, reflecting a higher risk of late recurrence in ER/PR+ HER2+ BC patients treated with chemotherapy alone. However, none of the individual gene, axis, or intrinsic subtypes were associated with the risk of late recurrence in patients treated with trastuzumab. Therefore, future studies are needed to identify biomarkers for the risk of late recurrence in HER2+ BC patients treated with adjuvant trastuzumab. Support: BCRF-19-161; U10CA180821, U10CA180882, Genentech. https://acknowledgments.alliancefound.org; Clinicaltrials.gov Identifier: NCT00005970 Citation Format: Saranya Chumsri, Zhuo Li, Nadine Norton, Alvaro Moreno-Aspitia, Gerardo Colon-Otero, Keith L. Knutson, Antonio C. Wolff, Edith A. Perez, E. A. Thompson. Effects of Intrinsic Subtypes and 21-gene Assay on the Early and Late Recurrence Risks in Patients with Early Stage HER2+ Breast Cancer: An Analysis of the North Central Cancer Treatment Group (NCCTG) N9831 (Alliance) Trial [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-11-05.