ENDOMETRIAL CANCER: Data from SGO 2020 indicate survival benefit for the addition of trastuzumab to standard chemo for those with advanced ERBB2-expressing (HER2+) disease (OS 24.4 versus 29.6 months)

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April 27, 2020

SCIENTIFIC

Randomized phase II trial of carboplatin-paclitaxel compared to carboplatin-paclitaxel-trastuzumab in advanced or recurrent uterine serous carcinomas that overexpress Her2/neu (NCT01367002): Updated survival analysis

SGO, 28 March 2020

Objective: HER2/Neu is a growth-factor receptor expressed in 30% of uterine serous carcinomas (USC). Based on the preliminary results of a multicenter, randomized phase II trial, trastuzumab (a humanized monoclonal antibody targeting Her2/Neu) in combination with carboplatin/paclitaxel is now recognized as an alternative standard in treating advanced or recurrent HER2/Neu+ USC. Herein, we report updated survival data.

 

Method: Eligible patients had primary stage III–IV or recurrent, HER2/neu+ disease. Patients were randomized to receive carboplatin/paclitaxel (control) for 6 cycles ± intravenous trastuzumab (experimental) until progression or toxicity. The primary endpoint was progression-free survival (PFS), and secondary endpoints were toxicity and overall survival (OS). Survival differences between treatment arms were assessed for significance via 1-sided log-rank tests.

Results: Forty-three progressions and 38 deaths (44 PFS events) occurred among 58 evaluable patients; median follow-up was 25.9 months (range 0.33–91 months). Among all patients, updated PFS continued to favor the trastuzumab arm, with medians of 8.0 (control) versus 12.9 (experimental) months (P = 0.005, HR = 0.46, 90% CI 0.28–0.76). Similarly, updated median PFS was 9.3 (control) versus 17.7 (experimental) months among 41 stage III–IV patients undergoing primary treatment (P = 0.015, HR = 0.44, 90% CI 0.23–0.83), and was 7.0 (control) versus 9.2 (experimental) months among 17 patients with recurrent disease (P = 0.004, HR = 0.12, 90% CI 0.03–0.48). Among all patients, OS was significantly higher in the trastuzumab arm than in the control arm, with medians of 24.4 (control) versus 29.6 (experimental) months, respectively (P = 0.046, HR = 0.58, 90% CI 0.34—0.99; Fig. 1). This benefit was particularly striking in stage III–IV patients, who had OS medians of 25.4 months (control) versus not reached (experimental, P = 0.041, HR = 0.49, 90% CI 0.25–0.97). In a subgroup analysis, no significant OS benefit from trastuzumab was observed in patients with recurrent disease. Finally, long-term toxicity was not different between treatment arms.

Conclusion: In this updated survival analysis of a randomized phase II trial, the addition of trastuzumab to carboplatin/paclitaxel increased PFS and OS in women with advanced/recurrent, HER2/Neu+ uterine serous carcinoma. The greatest benefit was observed in women with stage III–IV disease who were treated upfront.