A Multicenter Phase II Trial of Ipilimumab and Nivolumab in Unresectable or Metastatic Metaplastic Breast Cancer: Cohort 36 of Dual Anti–CTLA-4 and Anti–PD-1 Blockade in Rare Tumors (DART, SWOG S1609)

Sylvia Adams, Megan Othus, Sandip Pravin Patel, Kathy D. Miller, Rashmi Chugh, Scott M. Schuetze, Mary D. Chamberlin, Barbara J. Haley, Anna Maria V. Storniolo, Mridula P. Reddy, Scott A. Anderson, Collin T. Zimmerman, Anne P. O’Dea, Hamid R. Mirshahidi, Jordi Rodon Ahnert, Frank J. Brescia, Olwen Hahn, Jane M. Raymond, David D. Biggs, Roisin M. ConnollyElad Sharon, Larissa A. Korde, Robert J. Gray, Edward Mayerson, Melissa Plets, Charles D. Blanke, Young Kwang Chae, Razelle Kurzrock

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Purpose: Metaplastic breast cancer (MpBC) is a rare aggressive subtype that responds poorly to cytotoxics. Median survival is approximately 8 months for metastatic disease. We report results for advanced MpBC treated with ipilimumab + nivolumab, a cohort of S1609 for rare cancers (DART: NCT02834013). Patients and Methods: Prospective, open-label, multicenter phase II (two-stage) trial of ipilimumab (1 mg/kg i.v. every 6 weeks) plus nivolumab (240 mg i.v. every 2 weeks) for advanced MpBC. Primary endpoint was objective response rate (ORR). Secondary endpoints included progression-free survival (PFS), overall survival (OS), and toxicity. Results: Overall, 17 evaluable patients enrolled. Median age was 60 years (26–85); median number of prior therapy lines was 2 (0–5). ORR was 18%; 3 of 17 patients achieved objective responses (1 complete, 2 partial responses; 2 spindle cell, 1 chondromyxoid histology), which are ongoing at 28+, 33+, and 34+ months, respectively. Median PFS and OS were 2 and 12 months, respectively. Altogether, 11 patients (65%) experienced adverse events (AE), including one grade 5 AE. Eight patients (47%) developed an immune-related AE (irAE), with adrenal insufficiency observed in all 3 responders. Responses occurred in tumors with low tumor mutational burden, low PD-L1, and absent tumor-infiltrating lymphocytes. Conclusions: The ipilimumab and nivolumab combination showed no new safety signals and met its primary endpoint with 18% ORR in advanced, chemotherapy-refractory MpBC. All responses are ongoing at >2 to almost 3 years later. The effect of ipilimumab and nivolumab was associated with exceptional responses in a subset of patients versus no activity. This combination warrants further investigation in MpBC, with special attention to understanding mechanism of action, and carefully designed to weigh against the significant risks of irAEs.

Original languageEnglish (US)
Pages (from-to)271-278
Number of pages8
JournalClinical Cancer Research
Volume28
Issue number2
DOIs
StatePublished - Jan 15 2022
Externally publishedYes

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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