Despite the proven benefit of adding an immune checkpoint inhibitor (ICI) to preoperative chemotherapy for patients with triple-negative breast cancer (TNBC), the NeoTRIP Michelangelo trial stumbled at the finish line, showing that adding atezolizumab (Tecentriq) to nab-paclitaxel and carboplatin followed by surgery and adjuvant anthracycline-based chemotherapy did not improve 5-year event-free survival (EFS), compared with the same regimen without atezolizumab.
chair of the international breast cancer research committee at Fondazione Michelangelo in Milan.
“I strongly believe that the results of NeoTRIP, rather than being viewed as negative, should bring forth the search for dependable and widely applicable predictors of ICIs’ benefit in women with operable triple negative breast cancer,” he said in an oral abstract session at the annual meeting of the European Society for Medical Oncology.
Other neoadjuvant trials with different agents have shown benefit from the addition of an ICI to chemotherapy for patients with TNBC, Dr. Gianni noted, with pembrolizumab (Keytruda) in Keynote-522, durvalumab (Imfinzi) in GeparNuevo, and with atezolizumab in IMpassion031.
NeoTRIP results
Dr. Gianni and colleagues had previously reported that adding atezolizumab to neoadjuvant carboplatin/nab-paclitaxel did not significantly improve pathologic complete response rates (pCR) in the randomized trial, although other trials of neoadjuvant ICIs in this population had shown a pCR benefit.
“Our analysis of NeoTRIP supports that pCR may not be an appropriate surrogate endpoint for the role of ICIs in early TNBC,” they wrote in that analysis.
At ESMO 2023, the investigators presented 5-year event-free survival rates, the primary study endpoint, and results of an exploratory analysis of predictive biomarkers.
In the phase 3 trial, patients with HER2-negative, estrogen receptor–negative, and progesterone receptor–negative early high-risk or locally advanced unilateral breast cancer were randomly assigned to receive eight cycles of carboplatin plus nab-paclitaxel with or without atezolizumab, followed by surgery and four cycles of an anthracycline-based chemotherapy regimen of the investigators choice.
A total of 280 patients were included in the intention-to-treat (ITT) population, including 138 assigned to receive atezolizumab and 142 who received chemotherapy alone.
Of these groups. 119 and 120, respectively, went on to surgery and were eligible for adjuvant chemotherapy. In all, 79 patients (66%) in the atezolizumab arm and 90 (75%) in the no-atezolizumab arm completed the four planned cycles of postoperative chemotherapy.
At a median follow-up of 54 months, the EFS rate with atezolizumab was 70.6%, compared with 74.9% without atezolizumab, translating into a nonsignificant hazard ratio of 1.076 for disease progression while on primary therapy or disease recurrence after surgery, or death from any cause, including unknown causes.
Pathologic complete responses key
In multivariate analysis, significant predictors for better EFS included achievement of a pCR; disease stage (early high risk vs. locally advanced); programmed death ligand-1 (PD-L1) levels above 1% as assessed by the SP142 assay; and higher levels of stromal tumor-infiltrating lymphocytes, but these factors were not predictive of atezolizumab benefit, Dr. Gianni said.