Patients with early triple-negative breast cancer receiving Imfinzi in addition to neoadjuvant chemotherapy saw increased survival rates and complete responses to treatment.
Patients with early triple-negative breast cancer (TNBC) could benefit from the addition of Imfinzi (durvalumab) to neoadjuvant (pre-treatment therapeutics) anthracycline and taxane–based chemotherapy, according to study results presented at the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting.
Results from the trial indicated that patients who received Imfinzi with neoadjuvant chemotherapy achieved a pathologic complete response (lack of signs of cancer in tissue samples removed during surgery or a biopsy after treatment) of 53.4% compared to 44.2% in the group that did not.
“(Patients who were) stage 2a and higher, and younger patients, had a larger benefit from adding (Imfinzi),” said lead study author Dr. Sibylle Loibl, chief executive officer and chair of the German Breast Group, during a presentation of the data.
The addition of PD-1 and PD-L1 inhibitors, such as Imfinzi, to single-agent chemotherapy has been shown to improve progression-free survival (or when cancer does not continue to spread) in patients with PD-L1–positive metastatic TNBC. Moreover, rates of pathologic complete response have been observed to improve with the addition of PD-1 and PD-L1 inhibitors to neoadjuvant chemotherapy.
The study authors enrolled 174 patients (median age, 49.5 years) with early TNBC onto the trial, during which they either received Imfinzi or placebo for two weeks. Every 28-day cycle, patients in the Imfinzi group were observed. If they achieved clinical response, then treatment followed with Ellence (epirubicin) and cyclophosphamide on day one of every 14-day cycle for eight weeks, plus Imfinzi followed by surgery.
Measuring pathologic complete response was the main goal of the study. Additional goals included assessing invasive disease-free survival (time without invasive cancer recurrence), distant disease-free survival (the amount of time after primary treatment that the patient survives without any signs or symptoms), and overall survival (length of time from either diagnosis or start of treatment that a patient is still alive).
After a median follow-up of 43.7 months, patients treated with Imfinzi had a three-year invasive disease-free survival rate of 85.6% versus 77.2% in the placebo group. Moreover, patients receiving Imfinzi achieved a three-year distant disease-free survival rate of 91.7%, while those in the placebo group saw 78.4%. Three-year overall survival rates of 95.2% and 83.5% were reported in the Imfinzi and placebo groups.
At the same follow-up, 34 patients achieved invasive disease-free survival, 12 of which received Imfinzi. Distant relapse occurred in six patients who received Imfinzi, versus 13 who did not. An additional four patients in the Imfinzi group experienced invasive locoregional relapse (or when a new tumor is developed), while five occurred in the placebo group.
During the trial, two patients receiving Imfinzi developed invasive contralateral breast cancer and three receiving placebo also developed a second cancer.
An invasive disease-free survival subgroup analysis was also included on the study.
When examining invasive disease-free survival by pathologic complete response, the authors reported that patients with a pathologic complete response who were treated with Imfinzi achieved a three-year invasive disease-free survival rate of 95.5%, while non-pathologic complete response patients who received the same treatment had a rate of 76.3%.
“In the subgroup analysis, the patients overexposed to (Imfinzi) alone seemed to derive a larger benefit in terms of an increased (pathologic complete response),” explained Loibl.
Additionally, patients in the Imfinzi group who experienced a pathologic complete response had a three-year distant disease-free survival of 100% versus 84.3% in non-pathologic complete response patients. Patients in the placebo group had a three-year distant disease-free survival rate of 86.1% and 71.9% in pathologic complete response and non-pathologic complete response patients, respectively. Lastly, patients who achieved a pathologic complete response in the Imfinzi group had a three-year overall survival rate of 100% versus 92% in non-pathologic complete response patients, while in the placebo group, patients had an overall survival rate of 88.9% and 78.8% in the pathologic complete response and non-pathologic complete response patients, respectively.
“Similar results were seen in the (invasive disease-free survival), (distant disease-free survival) and (overall survival) analysis,” Loibl explained. “There were absolutely no (distant disease-free survival events in the Imfinzi group, (as well as) no death.”
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