medwireNews: Etirinotecan pegol does not improve the overall survival (OS) of people with breast cancer and stable brain metastases relative to physicians’ choice of single-agent chemotherapy, show trial data.
“The phase 3 ATTAIN randomized clinical trial did not replicate the positive OS benefit of treatment with etirinotecan pegol compared with chemotherapy in patients with breast cancer and [brain metastases] that was observed in BEACON,” write Debu Tripathy (The University of Texas MD Anderson Cancer Center, Houston, USA) and co-investigators in JAMA Oncology.
Median OS was 7.8 months for the 92 patients with pretreated, nonprogressive brain metastases who were randomly assigned to receive etirinotecan pegol 145 mg/m2 every 21 days and a comparable 7.5 months for their 86 counterparts instead given physicians’ choice of single-agent eribulin, ixabepilone, vinorelbine, gemcitabine, paclitaxel, docetaxel, or nab-paclitaxel.
Progression-free survival was also similar for etirinotecan pegol and chemotherapy, at a median of 3.9 versus 3.3 months for central nervous system (CNS) metastases, and 2.8 versus 1.9 months for non-CNS metastases.
The researchers suggest that even though ATTAIN and BEACON had largely similar eligibility criteria, “the studies enrolled noncomparable populations,” which could explain the contradictory results.
“ATTAIN had more patients with triple-negative breast cancer (40%) than the BEACON [brain metastases] subgroup (27%), more patients had received prior eribulin-containing regimens (42%vs 24%), and fewer patients had prior [whole-brain radiotherapy] (49% vs 91%),” they write.
These findings emphasize “the need to closely mirror the original trial design in confirmatory studies,” conclude Tripathy and colleagues.
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