Basket Study of Tucatinib and Trastuzumab in Solid Tumors With HER2 Alterations

Confirmed ORR was defined as the percentage of participants with best overall response of complete response (CR) or partial response (PR) according to Response Evaluation Criteria in Solid Tumors (RECIST) criteria version (v)1.1 as assessed by investigator and was considered as confirmed when subsequent response was at least 4 weeks after initial response. As per RECIST v1.1, CR: disappearance of all target lesions. Any pathological lymph nodes (whether target or non-target) must have reduction in short axis to less than (<)10 millimeter (mm). PR: at least a greater than or equal to (>=)30 % decrease in the sum of diameters (SOD) of target lesions (longest for non-nodal target lesions and the short axes for nodal target lesions), taking as reference the baseline sum diameters. Disease progression (PD): at least >=20% relative increase in SOD of target lesion taking as reference the smallest sum on study (including baseline sum if that is the smallest on study).

DCR was defined as the percentage of participants with confirmed CR, PR, or stable disease (SD or non-CR/non-PD) according to RECIST v1.1 as assessed by investigator. As per RECIST v1.1, CR: disappearance of all target (T) lesions and non-target (NT) lesions. Any pathological lymph nodes (whether target or non-target) must have reduction in short axis to <10 mm. PR: at least >=30 % decrease in the SOD of target lesions (longest for non-nodal target lesions and the short axes for nodal target lesions), taking as reference the baseline sum diameters. PD: at least >=20% relative increase in SOD of target lesions taking as reference the smallest sum on study (including baseline sum if that is the smallest on study). SD: neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for PD, taking as reference the smallest SOD while on study and cannot have met criteria for PD previously.

DOR: time from first documentation of confirmed CR/PR to first documentation of PD according to RECIST v1.1 or death from any cause, whichever occurred earlier. Per RECIST v1.1, CR: disappearance of all T/NT lesions(L). Any pathological lymph nodes (whether T/NT) must have reduction in short axis to <10 mm. PR: at least >=30 % decrease in SOD of TL, taking reference baseline sum diameters. PD: at least >=20% relative increase in SOD of TL taking reference smallest sum on study. Participants who do not have PD & were still on study at time of an analysis/ who have started new anticancer treatment/discontinue prior to documentation of PD were censored at date of last adequate response assessment documenting absence of PD. Participants who had PD/death occurred after two/more consecutive missing scheduled response assessments were censored at date of last adequate response assessment of CR, PR, SD,/non-CR/non-PD. Kaplan-Meier method was used for evaluation.

PFS was defined as time from the date of treatment initiation to date of PD as per RECIST v1.1 or death from any cause, whichever occurred first . As per RECIST v1.1, PD: least >=20% relative increase in SOD of target lesions taking as reference the smallest sum on study (including baseline sum if that is smallest on study). Participants who do not have PD and were still on study at time of an analysis/ who have started new anticancer treatment/discontinue prior to documentation of PD were censored at date of last adequate response assessment documenting absence of PD. Participants who had PD or death occurred after two or more consecutive missing scheduled response assessments were censored at date of last adequate response assessment of CR, PR, SD,/non-CR/non-PD. Kaplan-Meier method was used for evaluation.

OS was defined as the time from treatment initiation to death due to any cause. For a participant who was not known to have died by the end of study follow-up, observation of OS was censored on the date the participant was last known to be alive (i.e., the date of last contact). Participants lacking data beyond the day of treatment initiation were censored on the date of treatment initiation (i.e., OS duration of 1 day). Kaplan-Meier method was used for evaluation.

An AE was any untoward medical occurrence in a participant or clinical investigational participant administered a medicinal product and which did not necessarily have a causal relationship with this treatment. A TEAE was defined as a newly occurring or worsening AE after the first dose of study treatment.

Treatment-emergent laboratory abnormalities were defined as abnormalities that are new or worsened on or after receiving the first dose of study treatment up to 30 days after the last dose of study treatment. The following laboratory abnormalities were assessed: A-) Hematology: hemoglobin decreased, leukocytes decreased, lymphocytes decreased and increased, neutrophils decreased and platelets decreased; B-) Chemistry: alanine aminotransferase increased, albumin decreased, alkaline phosphatase increased, aspartate aminotransferase increased, calcium corrected for albumin decreased and increased, creatinine increased, glomerular filtration rate estimated decreased, glucose decreased, lactate dehydrogenase increased, magnesium increased and decreased, potassium increased and decreased, sodium increased and decreased and total bilirubin increased.

Dose modification included dose hold, dose reduction, or discontinuation of drugs. Dose reductions or treatment interruption/discontinuation were made at the discretion of the investigator.

An adverse event of special interest (AESI) were any serious or nonserious AE that were of scientific or medical concern as defined by the sponsor and specific to the program, for which ongoing monitoring and rapid communication to the sponsor were appropriate. A TEAE was defined as a newly occurring or worsening AE after the first dose of study treatment (tucatinib, trastuzumab or fulvestrant). AESIs for this study were related to hepatoxicity.