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. Author manuscript; available in PMC: 2022 Jun 15.
Published in final edited form as: Nature. 2021 Dec 15;600(7890):727–730. doi: 10.1038/s41586-021-04161-3

Extended Data Table 2.

Disposition of study treatment

Efficacy population Intention-to-treat population
Variable — no. (%) Pembrolizumab group (N=133) Placebo group (N=131) Pembrolizumab group (N=217) Placebo group (N=217)

Started 133 130 217 216
Discontinued all study treatment 79 (59.4) 93 (71.5) 90 (41.5) 112 (51.9)
 Adverse event 7 (5.3) 10(7.7) 10(4.6) 14(6.5)
 Clinical progression 4 (3.0) 9 (6.9) 6 (2.8) 12 (5.6)
 Non-study anticancer therapy 2(1.5) 3 (2.3) 2 (0.9) 3(1.4)
 Physician decision 1 (0.8) 2(1.5) 1 (0.5) 2 (0.9)
 Radiographic progression 59 (44.4) 64 (49.2) 65 (30.0) 76 (35.2)
 Withdrawal by participant 6 (4.5) 5 (3.8) 6 (2.8) 5 (2.3)
Continuing any study treatment 54 (40.6) 37 (28.5) 127 (58.5) 104 (48.1)

All percentages are calculated out of the number of participants who started study treatment. The treatment regimen included trastuzumab and chemotherapy in both groups.