medwireNews: Adding the PD-L1 inhibitor durvalumab to neoadjuvant chemotherapy may improve survival outcomes in people with triple-negative breast cancer, show GeparNUEVO data presented at the 2021 ASCO Annual Meeting.
Sibylle Loibl, from the German Breast Group in Neu-Isenberg, told delegates that, among 174 participants in the phase 2 trial, there were 12 invasive disease-free survival (DFS) events in the durvalumab arm and 22 in the placebo arm, after a median 43.7 months of follow-up. These were predominantly distant or invasive locoregional relapses in both cases, but there were three cases of secondary malignancies and one death among patients in the placebo group, while neither of these events occurred in the durvalumab group.
The randomly assigned treatment schedule involved an initial 2-week window phase in which individuals received intravenous durvalumab 0.75 mg (n=88) or placebo (n=86). After this, both groups received additional nab-paclitaxel 125 mg/m² weekly for 12 weeks then epirubicin 90 mg/m2 and cyclophosphamide 600 mg/m2 every 2 weeks for 4 cycles.
Loibl reported that 3-year invasive DFS was significantly higher with durvalumab than with placebo, at 85.6% versus 77.2%, corresponding to a significant 52% lower risk for invasive DFS events.
Individuals in the durvalumab group also had significantly lower 3-year distant DFS (91.7 vs 78.4%) and overall survival (95.2 vs 83.5%) rates compared with those in the placebo group, with significant risk reductions for each outcome of 69% and 76%, respectively.
Subgroup analyses suggested that PD-L1 positive patients may derive greater invasive DFS benefit from durvalumab than PD-L1 negative patients, and Loibl said that this finding “needs to be further explored.”
In addition, all three survival outcomes were significantly better in individuals who had a pathologic complete response (pCR) compared with those who did not, regardless of treatment arm. Specifically, people who had a pCR had significant 66%, 72%, and 73% lower risks for invasive relapse events, distant relapse events, and death, respectively, at 3 years.
Notably, there were no distant DFS events or deaths among the individuals who had a pCR and received durvalumab, and Loibl remarked that “patients achieving a pCR seemed to derive a larger benefit when durvalumab was added compared to the pCR placebo group.”
However, she also pointed out that the “pCR improvement with durvalumab was modest and requires further assessment of association of pCR and long-term outcomes with checkpoint inhibitor therapies.”
Indeed, the primary analysis of the study data revealed that the pCR rate at surgery was 53.4% with durvalumab and 44.2% with placebo, a nonsignificant difference.
Loible concluded: “Given these results, the value of adjuvant therapy with a checkpoint inhibitor after surgery needs to be further assessed.”
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