Extended Data Table 1.

Full list of adverse events

This table sums all treatment-related adverse events for all patients receiving at least 1 dose of ICI. Percentages for all grade adverse events total more than 100% due to more AEs per patient. Some AEs may be related to one another and were reported as one entity, always reporting the highest grade; for example, thyroid dysfunction includes hyperthyroidism and hypothyroidism, adrenal insufficiency with hypophysitis were graded as adrenal insufficiency. Elevated liver function tests were defined as an increased ALAT, ASAT, GGT, alkaline phosphatase, bilirubin, aPPT and/or INR. If elevated liver function tests were occurring simultaneously, only one AE reporting the highest grade was reported. IR hepatitis was based on an increase in liver function tests requiring treatment with immunosuppressive medication.

* All patients were classified as having secondary adrenal insufficiencies and all patients are still dependent on corticosteroid replacement.

# Ejection fraction decreased during ddAC treatment, however IR-myocarditis could not be ruled out. A total of 8 patients from cohorts A, B and C developed grade 3/4 treatment-related adverse events.

a) ID 14 (Cohort A) - Hyperthyroidism (grade 3) and chest pain (grade 3). Patient was diagnosed with hyperthyroidism leading to an orthostatic tremor requiring hospitalization of the patient. Symptoms were treated with beta-blockers.

b) ID 36 (Cohort B) - Hyperglycemia with diabetic ketoacidosis (grade 4) and adrenal insufficiency (grade 3). The patient remains insulin-dependent and dependent on corticosteroid replacement therapy.

c) ID 44 (Cohort C) - IR hepatitis (grade 3) with primary biliary cholangitis, treated with corticosteroids.

d) ID 47 (Cohort C) - IR hepatitis (grade 3), patient did not receive corticosteroid treatment.

e) ID 55 (Cohort C) - Pneumonitis (grade 3) with suspicion of pulmonary sarcoidosis, treated with corticosteroids.

f) ID 59 (Cohort C)- Adrenal insufficiency (grade 3), still dependent on corticosteroid replacement therapy.

g) ID 65 (Cohort C) - Colitis (grade 3), treated with corticosteroids.

h) ID 66 (Cohort C)- IR hepatitis (grade 4), treated with corticosteroids.