Abstract PS05-07: Early prediction of response to Neoadjuvant Immunotherapy in Triple Negative Breast Cancer (TNBC) with DCE-MRI

Abstract Purpose: Neoadjuvant immunotherapy (NIT) in combination with neoadjuvant chemotherapy (NCT) was recently approved for treatment of TNBC patients with increased rates of pathologic complete response (pCR) compared to NCT alone. The aim of this study was to evaluate if dynamic contrast-enhanced (DCE)-MRI performed after 2 and/or 4 cycles of NIT + NCT, can predict which patients will achieve pCR, potentially triaging them to continuation of NIT+NCT or, when appropriate, to de-escalation trials. Alternatively, identified chemoresistant tumors who are unlikely to achieve pCR may be directed to other treatment strategies, including novel targeted trials, and avoid the unnecessary toxicity of NIT. Methods and Materials: Preliminary analysis included 64 patients from prospective IRB-approved study (NCT02276443) with stage I-III TNBC who underwent DCE-MRI at baseline (BL), after 2 cycles (C2), and 4 cycles (C4) of NIT combined with standard of care NCT (Paclitaxel +/- carboplatin). Tumor volumes were calculated using 3 axis measurements of the index lesion at the DCE MRI and percent tumor volume reduction (TVR) between BL, C2, and C4 was calculated. pCR was assessed at surgery after completion of neoadjuvant treatment. Correlation between pCR and TVR was evaluated using ROC analysis. Results: 59% (38/64) of TNBC patients achieved pCR after NIT+NCT. DCE-MRI after 2 cycles of NIT+NCT was able to predict pCR with an AUC of 0.71 (95% CI: 0.57-0.84). TVR 90% at C2 predicted pCR with PPV 86%, and TVR 35% predicted chemoresistance with NPV 100%. Following 4 cycles of treatment DCE-MRI was able to predict pCR with an AUC of 0.81 (95% CI: 0.69-0.92). TVR 95% at C4 was predictive of chemosensitivity with PPV 82%, while TVR 75% was predictive of chemoresistance with NPV 100%. Conclusions: DCE-MRI volumetric changes early during NIT + NCT were able to predict pCR status of TNBC patients as either excellent responders or nonresponders, triaging them to SOC neoadjuvant therapy with option for de-escalation trials, or targeted therapies, respectively. These preliminary results will be validated in the larger cohort after completion of the ongoing prospective clinical trial. Citation Format: Gaiane Rauch, Mary Guirguis, Miral Patel, Rosalind Candelaria, Rania Mohamed, Tanya Moseley, H. T. Carisa Le-Petross, Jessica Leung, Gary Whitman, Deanna Lane, Marion Scoggins, Frances Perez, Jia Sun, Sanaz Pashapoor, Zhan Xu, Jason White, Peng Wei, Brandy Reed, Jong Bum Son, Ken-Pin Hwang, Bikash Panthi, Anil Korkut, Lei Huo, Kelly Hunt, Alyson Clayborn, Jennifer Litton, Vicente Valero, Debu Tripathy, Clinton Yam, Wei Yang, Jingfei Ma, Beatriz Adrada. Early prediction of response to Neoadjuvant Immunotherapy in Triple Negative Breast Cancer (TNBC) with DCE-MRI abstract. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PS05-07.