A Phase 2 Study of Sitravatinib in Combination With PD-(L)1 Checkpoint Inhibitor Regimens in Patients With Advanced or Metastatic Urothelial Carcinoma

An AE was defined as any reaction, side effect or other undesirable medical event that occurred during participation in a clinical trial, regardless of treatment group or suspected causal relationship to study treatment. Any clinically significant changes from baseline in laboratory results were recorded as AEs.

An SAE was defined as any event that resulted in death, was life-threatening (immediate risk of death), required inpatient hospitalization or prolongation of existing hospitalization; resulted in persistent or significant disability/permanent damage (substantial disruption of the ability to conduct normal life functions), a congenital anomaly/birth defect, or may have jeopardized the participant and may have required medical or surgical intervention to prevent intensive treatment in an emergency room or at home (e.g. for allergic bronchospasm, blood dyscrasias or convulsions) that do not result in inpatient hospitalization, development of drug dependency or drug abuse.

A treatment-related adverse event was defined as an adverse event determined to have a possible causal relationship to the study treatment(s) by the investigator. An adverse event was defined as any reaction, side effect or other undesirable medical event that occurred during participation in a clinical trial. Any clinically significant changes from baseline in laboratory results were recorded as adverse events.

DOR was defined as the time from date of the first documentation of objective tumor response (CR or PR) to the first documentation of objective progression of disease (PD) per RECIST V1.1, or to death due to any cause in the absence of documented PD. CR was defined as complete disappearance of all target lesions with the exception of nodal disease. All target nodes must have decreased to normal size (short axis < 10 mm). PR was defined as a greater than or equal to 30% decrease under baseline of the sum of diameters of all target measurable lesions. PD was defined as 20% increase in the sum of diameters of target measurable lesions above the smallest sum observed (over baseline if no decrease in the sum is observed during therapy) with a minimum absolute increase of 5 mm.

Per the statistical analysis plan (SAP), Cohort 9 arms are grouped as pre-specified as there was never intent to compare efficacy endpoints across Cohort 9 dose levels.

Clinical Benefit Rate (CBR) was defined as the number of participants documented to have a confirmed CR, PR, or stable disease (SD), per RECIST V1.1, documented during at least 1 on-study assessment. CR was defined as complete disappearance of all target lesions with the exception of nodal disease. All target nodes must have decreased to normal size (short axis < 10 mm). PR was defined as a greater than or equal to 30% decrease under baseline of the sum of diameters of all target measurable lesions. SD was defined as target lesions increasing by less than 20% from the nadir, but enough that a previously documented 30% decrease no longer holds.

PFS was defined as the time from date of first study treatment to first PD per RECIST V1.1, or death due to any cause in the absence of documented PD.

Survival was defined as the time from date of first study treatment to death due to any cause. Kaplan-Meier (product limit) estimates of the percentage of participants who died at 1-year was calculated to estimate the 1-year survival rate, defined as the percentage of participants alive at 1 year. Confidence Intervals were calculated based on Greenwood's formula. Participants who discontinued prior to 1-year were censored on the last date that they were known to be alive. For participants with no follow-up after first dose of study drug, survival rate was censored at the date of first dose (Day 1).

OS was defined as the time from date of first study treatment to death due to any cause.

Blood draws for analysis of blood plasma concentrations of sitravatinib were collected following electrocardiograms and assessment of vital signs. Concentration data below the limit of quantification were set to 0.

A DLT was defined as any of the following events considered to be causally related to treatment with sitravatinib in combination with pembrolizumab and enfortumab in the lead-in dose escalation part of Cohort 9 (as pre-specified): hematological DLTs (Grade 4 neutropenia, thrombocytopenia, anemia unexplained by underlying disease, ≥Grade 3 febrile neutropenia or neutropenia with significant clinical sequelae, or any requirement for a platelet transfusion), non-hematological DLTs (≥Grade 4 infusion related reaction, non-hematological toxicity, Grade 3 infusion related reaction that does not resolve within 24 hours, hypertension that cannot be controlled with medical therapy), other Grade 3 non-hematologic toxicity lasting for >3 days, with exceptions, Grade 2 pneumonitis or colitis, ≥Grade 3 non-hematological laboratory abnormalities, alanine transaminase>3 x upper limit of normal (ULN) with bilirubin> 2xULN, and other related toxic effects may have been assessed as DLTs.