The European Commission ( EC ) has granted marketing authorization for Tukysa ( Tucatinib ) in combination with Trastuzumab and Capecitabine for the treatment of adult patients with HER2-positive locally advanced or metastatic breast cancer who have received at least two prior anti-HER2 treatment regimens.
Tucatinib is an oral, small molecule tyrosine kinase inhibitor ( TKI ) of HER2, a protein that contributes to cancer cell growth.
In the HER2CLIMB pivotal trial, the Tucatinib combination regimen has improved overall and progression-free survival compared to Trastuzumab and Capecitabine alone, including in patients with active, untreated or progressing brain metastases.
Patients who received Tucatinib in combination with Trastuzumab and Capecitabine in the pivotal trial had a 46% reduction in the risk of cancer progression or death ( PFS ), the primary endpoint, compared to patients who received Trastuzumab and Capecitabine alone ( hazard ratio, HR=0.54 [ 95% Confidence Interval ( CI ): 0.42, 0.71 ]; p less than 0.00001 ) and improved overall survival with a reduction in the risk of death by 34% ( HR=0.66 [ 95% CI: 0.50, 0.87 ]; p=0.0048 ).
The most common adverse reactions occurring in 20% or more of patients who received Tucatinib were diarrhea, nausea, vomiting, stomatitis, AST increase, ALT increase, and rash.
The pivotal trial, HER2CLIMB, is a randomized ( 2:1 ), double-blind, placebo-controlled, active comparator, global trial that enrolled 612 patients with HER2-positive unresectable locally advanced or metastatic breast cancer who had previously received, either separately or in combination, Trastuzumab, Pertuzumab, and Trastuzumab emtansine ( T-DM1 SmPC ).
Tucatinib is an oral medicine that is a tyrosine kinase inhibitor of the HER2 protein. In vitro, Tucatinib inhibites phosphorylation of HER2 and HER3, resulting in inhibition of downstream MAPK and AKT signaling and cell growth ( proliferation ), and showed anti-tumor activity in HER2-expressing tumor cells.
In vivo, Tucatinib inhibites the growth of HER2-expressing tumors.
The combination of Tucatinib and the anti-HER2 antibody Trastuzumab has shown increased anti-tumor activity in vitro and in vivo compared to either medicine alone.
Patients with HER2-positive breast cancer have tumors with high levels of a protein called human epidermal growth factor receptor 2 ( HER2 ), which promotes the growth of cancer cells.
In 2020, more than two million new cases of breast cancer were diagnosed worldwide, including 531,086 in Europe.
Between 15 and 20% of breast cancer cases are HER2-positive.
HER2-positive breast cancer tends to be more aggressive and more likely to recur than HER2-negative breast cancer. Up to 50% of metastatic HER2-positive breast cancer patients develop brain metastases over time. ( Xagena )
Source: Seagen, 2021