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. 2025 Oct 8;23:546. doi: 10.1186/s12916-025-04364-9

Table 4.

Responses according to RECIST v1.1 produced by bireociclib combination therapy (part 2) – intention-to-treat population

Cohort A*
(n = 35)
Cohort B*
(n = 28)
Cohort C*
(n = 67)
Best overall response, n (%)
CR 1 (2.9) 0 2 (3.0)
PR 19 (54.3) 16 (57.1) 29 (43.3)
SD 12 (34.3) 9 (32.1) 29 (43.3)
PD 0 3 (10.7) 7 (10.4)
Not evaluable 3 (8.6) 0 0
ORR (%, 95% CI) 57.1 (39.35–73.68) 57.1 (37.18–75.54) 46.3 (34.00–58.88)
DCR (%, 95% CI) 91.4 (76.94–98.20) 89.3 (71.77–97.73) 89.6 (79.65–95.70)
CBR (%, 95% CI) 71.4 (53.70–85.36) 78.6 (59.05–91.70) 71.6 (59.31–81.99)
Survival estimates
Median PFS (months, 95% CI) NR (20.83–NR) 26.3 (9.99–NR) 20.1 (8.90–27.14)
Median DoR (months, 95% CI) NR (NR–NR) 24.5 (9.26–NR) 21.8 (11.07–25.53)

*Cohort A: bireociclib plus letrozole/anastrozole group; Cohort B: bireociclib plus FULV first-line; Cohort C: bireociclib plus FULV second-line. Cohorts A and B included patients who had not received prior systemic treatment in the metastatic setting. Among these patients, de novo metastatic cases represented only a minority, as the majority had previously received adjuvant therapy. CBR clinical benefit rate; CI confidence interval; CR complete response; DCR disease control rate; DoR duration of response; FULV fulvestrant; NR not reached; ORR objective response rate; PD progressive disease; PFS progression-free survival; PR partial response; RECIST Response Evaluation Criteria in Solid Tumors; SD stable disease