What is ENHERTU?
ENHERTU is a prescription medicine used to treat adults who have human epidermal growth factor receptor 2 (HER2)-positive breast cancer that cannot be removed by surgery or that has spread to other parts of the body (metastatic), and who have received a prior anti-HER2 breast cancer treatment:
- for metastatic disease, or
- have breast cancer that has come back during or within 6 months of completing treatment for their early-stage breast cancer.
It is not known if ENHERTU is safe and effective in children.
How was ENHERTU studied in HER2-positive mBC?
ENHERTU was compared to ado-trastuzumab emtansine in a clinical study of 524 people who:
- Had HER2-positive breast cancer that had spread to other parts of their body or could not be removed by surgery, and
- Had received a prior treatment for HER2-positive metastatic breast cancer (mBC) or had cancer come back during or within 6 months of treatment after surgery
In this trial, 261 people were treated with ENHERTU and 263 were treated with ado-trastuzumab emtansine.
ENHERTU was studied in many types of adults, including those with:
- Different ages*
- Various hormone receptor (HR) statuses
- Tumors that had spread (metastasized) to other parts of the body, including the liver, lungs, and bones
- Tumors that had spread to the brain and were stable
*Patients studied were 20 to 83 years of age.
What were the results of the ENHERTU study?
Progression-free survival
Initial results (May 2021)
With ENHERTU, people lived longer without their cancer growing or spreading compared to ado-trastuzumab emtansine
Compared to ado-trastuzumab emtansine, people who received ENHERTU were:
72% more likely
to be alive without their cancer progressing
This is called median progression-free survival. A median is the middle number in a set of numbers. Median progression-free survival (mPFS) measures the amount of time that half of the people enrolled in the study were on treatment before their cancer started growing or spreading.
At the time of data analysis, median progression-free survival was not yet reached for people receiving ENHERTU. This means that more than half of people receiving ENHERTU were alive without their cancer growing or spreading. This compares to half of the people receiving ado-trastuzumab emtansine who reached median progression-free survival at about 7 months before their cancer began to grow or spread.
- 67% (174 of 261) of people treated with ENHERTU were alive at the time of data analysis without their cancer progressing, compared to 40% (105 of 263) of people treated with ado-trastuzumab emtansine
Overall survival
Initial results (May 2021)
In the first assessment, overall survival results were not
available
Follow-up results (July 2022)
People receiving ENHERTU lived longer compared with people receiving ado-trastuzumab emtansine
- At the time of updated data analysis, more than 50% of people receiving ENHERTU or ado-trastuzumab emtansine were still alive†
- ENHERTU reduced the risk of death in patients by 36% vs ado-trastuzumab emtansine
- 65% (170 of 261) of people treated with ENHERTU were alive at the time of this data analysis (median follow-up was 28.4 months), and 52% (138 of 263) of people treated with ado-trastuzumab emtansine were alive at the time of data analysis (median follow-up was 26.5 months)
Updated results (November 2023)
Median overall survival with ENHERTU and ado-trastuzumab emtansine‡
- 52.6 months with ENHERTU and 42.7 months with ado-trastuzumab emtansine
This is called median overall survival. A median is the middle number in a set of numbers. Median overall survival is the length of time, from either the day of diagnosis or the start of treatment, that half the patients in a group are still alive.
†At the time of data analysis, since more than 50% of people receiving ENHERTU or ado-trastuzumab emtansine were still alive, the results could not be reported in months.
‡These study results were based on an exploratory analysis, which was not intended to compare the two treatments. The study was also open-label, meaning that both the patients and trial investigators knew which treatment patients received. Therefore, the results could have been influenced by people switching to another treatment, leaving the study, or other factors. This means the results of the exploratory analysis cannot be fully explained and may not be the effect of the treatment. Each person's experience may differ. Speak with your doctor about what you may expect.
Response to treatment
Initial results (May 2021)
In the first assessment, more people had their tumors shrink with ENHERTU than with ado-trastuzumab emtansine‡§
Overall response
83%
with ENHERTU
36%
with ado-trastuzumab emtansine
This is called overall response rate. Overall response rate is the proportion of patients who have a partial or complete response to therapy.
Of the people who responded to ENHERTU:
- 16% (39 of 248) of people achieved a complete response with ENHERTU and 8% (20 of 241) of people with ado-trastuzumab emtansine. A complete response means the tumor could not be seen on imaging tests
- 67% (166 of 248) of people achieved a partial response with ENHERTU and 28% (67 of 241) of people with ado-trastuzumab emtansine. A partial response means the tumor shrank by at least 30%
Updated results (July 2022)||
- 82% of people had their tumors shrink with ENHERTU
- 37% of people had their tumors shrink with ado-trastuzumab emtansine
Of the people who responded to ENHERTU in the updated assessment:
- 21% (52 of 246) of people achieved a complete response with ENHERTU and 9% (21 of 240) of people treated with ado-trastuzumab emtansine
- 61% (150 of 246) of people achieved a partial response with ENHERTU and 28% (67 of 240) of people treated with ado-trastuzumab emtansine
‡These study results were based on an exploratory analysis, which was not intended to compare the two treatments. The study was also open-label, meaning that both the patients and trial investigators knew which treatment patients received. Therefore, the results could have been influenced by people switching to another treatment, leaving the study, or other factors. This means the results of the exploratory analysis cannot be fully explained and may not be the effect of the treatment. Each person's experience may differ. Speak with your doctor about what you may expect.
§Based on the people in the first assessment with measurable disease (248 people who received ENHERTU and 241 people who received ado-trastuzumab emtansine). In the first assessment, 83% (205 of 248) of people had their tumors shrink with ENHERTU and 36% (87 of 241) of people with ado-trastuzumab emtansine.
||Based on the people in the updated assessment with measurable disease (246 people who received ENHERTU and 240 people who received ado-trastuzumab emtansine). In the updated assessment, 82% (202 of 246) of people had their tumors shrink with ENHERTU and 37% (88 of 240) of people with ado-trastuzumab emtansine.
Additional results
with ENHERTU
Initial results (May 2021)
Disease control
In the first assessment, 98% (242 of 248) of people treated with ENHERTU had their tumors respond to treatment in at least one of the following ways:
Shrink
or
Stop growing
This is called disease control rate. The disease control rate is the percentage of patients who have achieved complete response, partial response, or stable disease.¶
¶Not tested for statistical significance and not designed to show differences between treatments. Statistical significance describes a mathematical measure of difference between groups. The difference is statistically significant if it is greater than what might be expected to happen by chance alone.
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