Efficacy of antibody-drug conjugates in breast cancer: A systematic review and meta-analysis of randomized clinical trials.

Abstract

e13113 Background: Breast cancer (BC) is the 2nd most common cause of cancer related deaths in women. Antibody-drug conjugates are monoclonal antibodies conjugated to the cytotoxic payload and are directed towards cell surface proteins specific to tumor cells. This systematic review and meta-analysis aims to assess the efficacy of ADCs in breast cancer and comparison of different ADCs. Methods: A literature search was performed on PubMed, Embase, WOS, and clinicaltrials.gov with key words “breast neoplasms,” and “immunoconjugates” from the inception of data till 6/6/2022. Cochrane and PRISMA guidelines were followed to establish guidelines registered on Prospero (CRD42022329529). Out of 4,570 articles, seven randomized clinical trials (RCTs, N=5,302) were included. R programming language software with “meta” package was used for this meta-analysis. Results: In 7 RCTs (N=5,302), 4,834 patients had HER-2 positive disease while 468 patients were triple negative BC (TNBC). 1,486 patients had residual invasive disease while 3,816 patients had metastatic breast cancer (mBC). 3,389 patients were treated with ADC (235 with sacituzumab govitecan (saci-gov), 2,339 with trastuzumab emtansine (T-DM1) and 261 trastuzumab deruxtecan (T-der)), 2,105 patients were treated with chemotherapy regimens. In 4 RCTs on HER-2 patients (N=2,825), pooled HR of PFS and OS were 0.72 (95% CI=0.61-0.84, I2=71%) and 0.73 (95% CI=0.64-0.84, I2=20%), respectively, in favor of ADC. Risk of ORR was 1.48 (95% CI=0.84-2.60, I2=91%) in favor of ADC. In RCT on TNBC (N=468), HR of PFS and OS were 0.55 (95% CI=0.51-0.61) and 0.59 (95% CI=0.54-0.66), respectively, in favor of saci-gov (ADC). In RCT on HER-2 positive residual invasive breast cancer, HR of recurrence/death was 0.61 (95% CI=0.54-0.69) in favor of T-DM1. In an RCT by Cortes et al. (N=524) comparing two ADCs in HER-2 mBC, the HR of PFS and OS were 0.28 (95% CI= 0.22-0.37) and 0.55 (95% CI=0.36-0.86), respectively, in favor of T-der as compared to T-DM1. The RR of ORR and CR were 2.33 and 1.28, respectively, in favor of T-der. Conclusions: ADCs are significantly more effective than chemotherapy in patients with HER-2 positive mBC, HER-2 positive residually invasive BC, and metastatic TNBC in terms of improving survival and response rates. Among ADCs, T-der was significantly more effective than T-DM1 in patients with HER-2 positive mBC. More double blinded multicenter RCTs are needed to confirm these results.