Abstract Body (Do not enter title and authors here): Introduction: Immune checkpoint inhibitors (ICIs) are commonly used as anticancer agents linked with dramatic antitumor response but are associated with cardiotoxicity. Recent isolated reports have suggested ICIs may link with hypertension (HTN) after years of treatment. Yet, the timing and long-term ramifications of this HTN are unknown.

Methods: From a large cohort of well-phenotyped cancer patients treated with ICIs from 2011-2022, we assessed the incidence of new or worsened HTN [systolic blood pressure (SBP) ≥130 mmHg (or in a higher HTN stage) on two occasions within a three-month period or addition of an antihypertensive medication] after ICI initiation. Secondary endpoints included major cardiovascular events (MACE), defined as symptomatic arrhythmia, myocardial infarction, stroke, heart failure, or cardiac death. Observed incident HTN rates were compared to Framingham-predicted rates, using JNC 8 cutoffs of 140/90 mmHg. Landmark analysis, excluding patients who were observed to have new HTN but had SBPs ≥130 mmHg on two occasions within six-months prior to ICI initiation, identified patients with possible undiagnosed HTN. Multivariable regression and survival analysis were used to define factors associated with new worsened HTN and MACE and the relationship between SBP increase and MACE risk. Further, the effect of standard antihypertensive classes on the prevention of ICI-related HTN will be assessed.

Results: Overall, from 312 patients treated with ICIs (mean age 63.5 years, 67.4% baseline HTN, 11.0% on dual ICI-therapy), 50.0% (156/312) developed new or worsened HTN over a mean of 27 months follow-up. Cumulative incidence of new HTN by 1-year was 50.0% wherein the mean peak increase in SBP was 12 mmHg. In landmark analysis, excluding those with undiagnosed HTN and applying the JNC 8 cutoff of ≥140/90 mmHg, the observed new HTN rate was 21.4% at 1 year, >2-fold higher than the Framingham-predicted rate of 9.3% (RR 2.3, P<0.0001). In those with preexisting HTN, 49% developed worsened HTN. In multivariate analysis, only time on ICI treatment, ECOG status, and autoimmune disease history were associated with new or worsened HTN after ICI-initiation (P<0.05 for all). Further, only prior autoimmune disease and ECOG status associated with MACE; while beyond traditional cancer factors, only new or worsening HTN associated with lower mortality.

Conclusions: Collectively, these data suggest that HTN may be common with ICIs, and prognosticates survival.