{"product_id":"a-new-treatment-option-for-high-risk-her2-positive-early-breast-cancer-what-the-destiny-breast05-trial-means-for-patients","title":"A New Treatment Option for High-Risk HER2-Positive Early Breast Cancer: What the DESTINY-Breast05 Trial Means for Patients","description":"\u003cp\u003eIn a large international clinical trial called DESTINY-Breast05, researchers compared two antibody-drug conjugate medications in 1,635 patients with HER2-positive early breast cancer who still had invasive disease remaining after chemotherapy and HER2-targeted treatment before surgery. The newer drug, trastuzumab deruxtecan (T-DXd), reduced the risk of invasive cancer returning or death by 53% compared with the current standard drug, trastuzumab emtansine (T-DM1), with 3-year invasive disease-free survival of 92.4% versus 83.7%. However, T-DXd produced more cases of interstitial lung disease (9.6% vs. 1.6%), including two deaths, which means careful monitoring is essential. These results, published in the \u003cem\u003eNew England Journal of Medicine\u003c\/em\u003e, establish T-DXd as a powerful new option for patients at high risk of recurrence after neoadjuvant therapy.\u003c\/p\u003e\n\n\u003ch1\u003eA New Treatment Option for High-Risk HER2-Positive Early Breast Cancer: What the DESTINY-Breast05 Trial Means for Patients\u003c\/h1\u003e\n\n\u003ch2\u003eTable of Contents\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\u003ca href=\"#ddn-key-points\"\u003eKey Points\u003c\/a\u003e\u003c\/li\u003e\n\n  \u003cli\u003e\u003ca href=\"#background\"\u003eWhat Is HER2-Positive Breast Cancer and Why Does Residual Disease Matter?\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#why-it-matters\"\u003eWhy This Research Matters\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#study-design\"\u003eHow the Study Was Designed\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#participants\"\u003eWho Took Part in the Study\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#key-findings\"\u003eKey Findings: How Well Did T-DXd Work?\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#side-effects\"\u003eSide Effects: What Patients Experienced\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#limitations\"\u003eStudy Limitations\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#recommendations\"\u003eRecommendations for Patients\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#ddn-faq\"\u003eFrequently Asked Questions\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"#source\"\u003eSource Information\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003c!-- ddn:keypoints:start --\u003e\n\u003ch2 id=\"ddn-key-points\"\u003eKey Points\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eIn the DESTINY-Breast05 trial, T-DXd reduced the risk of invasive disease or death by 53% versus T-DM1 in high-risk HER2-positive early breast cancer.\u003c\/li\u003e\n\u003cli\u003eThree-year invasive disease-free survival was 92.4% with T-DXd versus 83.7% with T-DM1.\u003c\/li\u003e\n\u003cli\u003eInterstitial lung disease occurred in 9.6% of T-DXd patients versus 1.6% with T-DM1, including two deaths.\u003c\/li\u003e\n\u003cli\u003eT-DXd more often caused nausea, vomiting, and low neutrophils; T-DM1 more often caused low platelets and elevated liver enzymes.\u003c\/li\u003e\n\u003cli\u003eOverall survival data are not yet mature; the trend favors T-DXd but is not statistically significant.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- ddn:keypoints:end --\u003e\n\n\n\u003ch2 id=\"background\"\u003eWhat Is HER2-Positive Breast Cancer and Why Does Residual Disease Matter?\u003c\/h2\u003e\n\n\u003cp\u003eAbout 1 in 5 breast cancers are HER2-positive, meaning the cancer cells carry too much of a protein called human epidermal growth factor receptor 2 (HER2) on their surface. This protein acts like a growth switch, signaling the cancer cells to multiply. Doctors confirm HER2 positivity through tissue testing, using either an immunohistochemical (IHC) score of 3+, which means high levels of the protein are visible under a microscope, or a positive in situ hybridization (ISH) test, which detects extra copies of the HER2 gene.\u003c\/p\u003e\n\n\u003cp\u003ePatients with HER2-positive early breast cancer usually begin treatment with chemotherapy plus HER2-targeted drugs before surgery. This pre-surgery phase is called \u003cstrong\u003eneoadjuvant therapy\u003c\/strong\u003e; its goal is to shrink or eliminate the tumor before the surgeon removes it. Ideally, the tumor disappears completely. But some patients still have what doctors call \u003cstrong\u003eresidual invasive disease\u003c\/strong\u003e when the tissue is examined after surgery. This means that living cancer cells remained in the breast or lymph nodes despite the treatment.\u003c\/p\u003e\n\n\u003cp\u003eResidual disease is a red flag. It means the cancer was more stubborn than expected, and the risk of recurrence is substantially higher than for patients whose tumors vanish completely. This is especially true when cancer is found in the lymph nodes. Doctors now think of these patients as needing extra protection after surgery, and that is the focus of this trial.\u003c\/p\u003e\n\n\u003ch2 id=\"why-it-matters\"\u003eWhy This Research Matters\u003c\/h2\u003e\n\n\u003cp\u003eThe previous standard of care for these patients came from a trial called KATHERINE, which showed that giving the antibody-drug conjugate trastuzumab emtansine (T-DM1, brand name Kadcyla) after surgery improved outcomes compared with trastuzumab (Herceptin) alone. In that trial, invasive disease or death occurred in 91 patients (12.2%) in the T-DM1 group versus 165 patients (22.2%) in the trastuzumab group, a hazard ratio of 0.50 (95% confidence interval [CI], 0.39 to 0.64; P\u0026lt;0.001). Three-year invasive disease-free survival was 88.3% with T-DM1 versus 77.0% with trastuzumab.\u003c\/p\u003e\n\n\u003cp\u003eYet even with T-DM1, the risk was not eliminated. Death occurred in 89 patients (12.0%) in the T-DM1 group versus 126 patients (17.0%) in the trastuzumab group (hazard ratio, 0.66; 95% CI, 0.51 to 0.87; P=0.003), and 7-year overall survival was 89.1% versus 88.4%.\u003c\/p\u003e\n\n\u003cp\u003eSubgroup analyses of the KATHERINE trial showed particularly high risk in certain groups. Patients with advanced locoregional disease at diagnosis had a 3-year invasive disease-free survival of 76% and a 7-year survival of 67%. Patients whose lymph nodes were still positive after neoadjuvant therapy fared better but still faced meaningful risk: 3-year survival of 83% and 7-year survival of 72%. No substantial difference in central nervous system (CNS) recurrence was observed between the two treatment arms in KATHERINE.\u003c\/p\u003e\n\n\u003cp\u003eT-DXd offered hope for improvement. This drug, also called trastuzumab deruxtecan or Enhertu, is a newer HER2-directed antibody-drug conjugate. It has already transformed treatment for metastatic HER2-positive breast cancer, showing activity even against tumors that spread to the brain. The DESTINY-Breast05 trial was designed to test whether T-DXd could beat T-DM1 in the post-surgery (postneoadjuvant) setting for patients at high risk of recurrence.\u003c\/p\u003e\n\n\u003ch2 id=\"study-design\"\u003eHow the Study Was Designed\u003c\/h2\u003e\n\n\u003cp\u003eDESTINY-Breast05 is an ongoing phase 3, open-label, international, randomized trial. \"Phase 3\" means it is a large, definitive study comparing the new treatment against the current standard. \"Open-label\" means both doctors and patients knew which drug was being given. \"Randomized\" means patients were assigned to one of the two treatments by chance, like flipping a coin, which helps ensure the two groups are comparable.\u003c\/p\u003e\n\n\u003cp\u003eThe trial enrolled patients with centrally confirmed HER2-positive early breast cancer who had residual invasive disease after neoadjuvant therapy. Patients had to meet specific high-risk criteria. Some had inoperable disease at diagnosis, defined as either tumor stage T4 with any nodal stage N0 to N3 and no distant spread (M0), or tumor stage T1 to T3 with nodal stage N2 or N3 and M0. Others had operable disease at diagnosis, defined as tumor stage T1 to T3, nodal stage N0 or N1, and M0, but their lymph nodes were still positive after neoadjuvant therapy (pathological stage ypN1 to ypN3).\u003c\/p\u003e\n\n\u003cp\u003eAll patients had an Eastern Cooperative Oncology Group (ECOG) performance-status score of 0 or 1. This is a 5-point scale in which higher scores reflect greater disability; a score of 0 means fully active and a score of 1 means restricted in strenuous activity but able to walk and do light work, so these were relatively fit patients. All had completed neoadjuvant therapy that included at least 9 weeks of taxane-based chemotherapy and at least 9 weeks of HER2-directed treatment with trastuzumab, with or without pertuzumab. Randomization occurred within 12 weeks after the last surgical procedure.\u003c\/p\u003e\n\n\u003cp\u003ePatients were randomly assigned in a 1:1 ratio to receive either T-DXd (818 patients) or T-DM1 (817 patients). Both drugs were given intravenously on day 1 of each 21-day cycle, for a total of 14 cycles. The dose was 5.4 mg per kilogram of body weight for T-DXd and 3.6 mg per kilogram for T-DM1.\u003c\/p\u003e\n\n\u003cp\u003eRandomization was stratified according to four factors:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eDisease extent at diagnosis (operable vs. inoperable)\u003c\/li\u003e\n  \u003cli\u003eHormone-receptor status (positive vs. negative)\u003c\/li\u003e\n  \u003cli\u003ePathological nodal status after neoadjuvant therapy (positive [ypN1 to ypN3] vs. negative [ypN0])\u003c\/li\u003e\n  \u003cli\u003eHER2-targeted neoadjuvant therapy (single vs. dual)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003ePatients who stopped the trial drug early for any reason (except death or loss to follow-up) could receive standard HER2-targeted therapy to complete up to 14 cycles of HER2-targeted treatment after surgery. Hormonal therapy (endocrine therapy) was given to patients with hormone receptor-positive tumors according to local standards. Radiotherapy could be given at the same time as trial therapy or after it finished.\u003c\/p\u003e\n\n\u003cp\u003eKey exclusion criteria included a history of noninfectious interstitial lung disease or pneumonitis requiring glucocorticoid treatment, or current or suspected interstitial lung disease not ruled out by imaging at screening. This is important because lung inflammation became a central safety concern in this trial.\u003c\/p\u003e\n\n\u003cp\u003eThe primary end point was \u003cstrong\u003einvasive disease-free survival\u003c\/strong\u003e: the time from randomization until invasive cancer returns in the same area (ipsilateral locoregional), spreads to a distant site, appears in the opposite breast, or death from any cause. Second nonbreast primary cancers were not counted in this end point. The key secondary end point was \u003cstrong\u003edisease-free survival\u003c\/strong\u003e, which additionally counted noninvasive breast cancers (ductal carcinoma in situ) and second primary nonbreast cancers. Other end points included overall survival, distant recurrence-free interval, brain metastasis-free interval, and safety.\u003c\/p\u003e\n\n\u003cp\u003eAn important detail: the trial used an aggressive monitoring protocol for lung problems. All patients had a baseline low-dose, non-contrast chest CT at screening. Those receiving adjuvant radiotherapy had serial chest CTs at 6 weeks after starting treatment (before infusion at cycle 3), then every 12 weeks during treatment (before infusions at cycles 7 and 11), and at the 40-day follow-up. Patients receiving sequential radiotherapy had an additional chest CT after completing radiation before the first trial-drug infusion. All potential cases of interstitial lung disease or pneumonitis were reviewed by an independent adjudication committee, and management followed protocol-defined guidelines.\u003c\/p\u003e\n\n\u003cp\u003eThe trial planned to enroll 1,600 patients. Approximately 207 invasive-disease events or deaths were required to provide 80% power to detect a significant difference if the true hazard ratio was 0.675, corresponding to an improvement in 3-year invasive disease-free survival from 83.0% with T-DM1 to 88.2% with T-DXd. A single interim analysis was planned at about 70% of target events (prespecified efficacy boundary of 153 events, P\u0026lt;0.0183). An interim analysis of disease-free survival was planned only if the invasive disease-free survival boundary was crossed, with a boundary of 155 events and P\u0026lt;0.0144.\u003c\/p\u003e\n\n\u003ch2 id=\"participants\"\u003eWho Took Part in the Study\u003c\/h2\u003e\n\n\u003cp\u003eFrom December 4, 2020, through January 23, 2024, a total of 2,067 patients were screened, and 1,635 were randomly assigned: 818 to T-DXd and 817 to T-DM1. At the data-cutoff date of July 2, 2025, the median duration of follow-up was 29.9 months (range, 0.3 to 53.4) with T-DXd and 29.7 months (range, 0.1 to 54.4) with T-DM1.\u003c\/p\u003e\n\n\u003cp\u003eThe two groups were well balanced at baseline. The median age was 50.3 years (range, 24 to 78) in the T-DXd group and 50.6 years (range, 21 to 83) in the T-DM1 group. Most patients were younger than 65 years: 89.9% in the T-DXd group and 90.1% in the T-DM1 group. Nearly all patients were female: 99.5% and 99.6%, respectively.\u003c\/p\u003e\n\n\u003cp\u003eThe trial was truly international, with patients from Asia (47.9% vs. 46.5%), Europe (27.1% vs. 27.3%), North America and Australia (7.0% vs. 8.8%), and the rest of the world, including Argentina, Brazil, Chile, Czech Republic, Israel, Mexico, Peru, Poland, Romania, and Russia (18.0% vs. 17.4%). Nearly half the patients were Asian (48.8% vs. 47.2%), about 37-41% were White, and Black patients were underrepresented at just 2.7% and 1.6%.\u003c\/p\u003e\n\n\u003cp\u003eOther key characteristics included:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eHormone receptor-positive cancers: 71.0% vs. 71.4%\u003c\/li\u003e\n  \u003cli\u003eHormone receptor-negative cancers: 29.0% vs. 28.6%\u003c\/li\u003e\n  \u003cli\u003eInoperable disease at presentation: 52.7% vs. 51.9%\u003c\/li\u003e\n  \u003cli\u003eOperable disease at presentation: 47.3% vs. 48.1%\u003c\/li\u003e\n  \u003cli\u003ePositive lymph nodes after neoadjuvant therapy: 80.7% vs. 80.5%\u003c\/li\u003e\n  \u003cli\u003eMastectomy: 72.1% vs. 71.4%\u003c\/li\u003e\n  \u003cli\u003eBreast-conserving surgery: 27.9% vs. 28.6%\u003c\/li\u003e\n  \u003cli\u003eDual HER2-targeted neoadjuvant therapy (trastuzumab plus pertuzumab): 78.5% vs. 79.1%\u003c\/li\u003e\n  \u003cli\u003eSingle-agent trastuzumab neoadjuvant therapy: 21.5% vs. 20.9%\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eAll patients received taxane-based neoadjuvant chemotherapy (100% in both groups). About half also received a platinum compound (47.2% vs. 48.0%) or an anthracycline (51.7% vs. 48.8%). Adjuvant radiotherapy was given to 93.4% and 92.9% of patients, respectively, either concurrently with trial therapy (53.5% vs. 58.8%) or sequentially (39.9% vs. 34.1%).\u003c\/p\u003e\n\n\u003ch2 id=\"key-findings\"\u003eKey Findings: How Well Did T-DXd Work?\u003c\/h2\u003e\n\n\u003cp\u003eThe results strongly favored T-DXd. At the interim analysis data cutoff, 153 invasive-disease events or deaths had been reported: 51 (6.2%, about 1 in 16 patients) in the T-DXd group versus 102 (12.5%, about 1 in 8 patients) in the T-DM1 group. This corresponds to a hazard ratio of 0.47 (95% CI, 0.34 to 0.66; P\u0026lt;0.001), meaning T-DXd reduced the risk of invasive disease or death by 53% compared with T-DM1. The P value crossed the prespecified efficacy boundary of 0.0183.\u003c\/p\u003e\n\n\u003cp\u003eThree-year invasive disease-free survival was 92.4% (95% CI, 89.7 to 94.4) with T-DXd versus 83.7% (95% CI, 80.2 to 86.7) with T-DM1. In plain terms, of every 100 patients treated with T-DXd, about 92 remained free of invasive disease at 3 years, compared with about 84 of every 100 treated with T-DM1.\u003c\/p\u003e\n\n\u003cp\u003eThe key secondary end point of disease-free survival showed a nearly identical pattern. Invasive-disease events, noninvasive-disease events (such as ductal carcinoma in situ), or deaths occurred in 52 patients (6.4%) with T-DXd versus 103 patients (12.6%) with T-DM1 (hazard ratio, 0.47; 95% CI, 0.34 to 0.66; P\u0026lt;0.001). Three-year disease-free survival was 92.3% (95% CI, 89.5 to 94.3) versus 83.5% (95% CI, 79.9 to 86.4). This P value also crossed its efficacy boundary of 0.0144.\u003c\/p\u003e\n\n\u003cp\u003eOther end points also favored T-DXd:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDistant recurrence-free interval:\u003c\/strong\u003e Distant recurrence occurred in 42 patients (5.1%) with T-DXd versus 81 patients (9.9%) with T-DM1 (hazard ratio, 0.49; 95% CI, 0.34 to 0.71). Three-year freedom from distant recurrence was 93.9% versus 86.1%.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBrain metastasis-free interval:\u003c\/strong\u003e Brain metastasis developed in 17 patients (2.1%) with T-DXd versus 26 patients (3.2%) with T-DM1 (hazard ratio, 0.64; 95% CI, 0.35 to 1.17). Three-year freedom from brain metastasis was 97.6% versus 95.8%. This difference did not reach statistical significance, but the numbers of events were small.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eOverall survival:\u003c\/strong\u003e Death occurred in 18 patients (2.2%) with T-DXd versus 29 patients (3.5%) with T-DM1 (hazard ratio, 0.61; 95% CI, 0.34 to 1.10). Three-year survival was 97.4% versus 95.7%. Survival data are still early, and this difference was not yet statistically significant, but the trend favors T-DXd.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eMost first invasive-disease events were distant recurrences, meaning the cancer returned in organs away from the breast.\u003c\/p\u003e\n\n\u003ch2 id=\"side-effects\"\u003eSide Effects: What Patients Experienced\u003c\/h2\u003e\n\n\u003cp\u003eAt the data-cutoff date, 583 of 806 patients (72.3%) receiving T-DXd and 611 of 801 patients (76.3%) receiving T-DM1 had completed all 14 treatment cycles. Adverse events of grade 3 or higher (severe or medically significant events) occurred in 408 patients (50.6%) with T-DXd and 416 patients (51.9%) with T-DM1. Serious adverse events occurred in 140 patients (17.4%) with T-DXd and 109 patients (13.6%) with T-DM1.\u003c\/p\u003e\n\n\u003cp\u003eThe two drugs had quite different side effect profiles:\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eWith T-DXd,\u003c\/strong\u003e the most common adverse events were mainly gastrointestinal:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eNausea: 71.3% of patients (about 7 in 10)\u003c\/li\u003e\n  \u003cli\u003eConstipation: 32.0%\u003c\/li\u003e\n  \u003cli\u003eDecreased neutrophil count (neutropenia, a low level of infection-fighting white blood cells): 31.6%\u003c\/li\u003e\n  \u003cli\u003eVomiting: 31.0%\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cstrong\u003eWith T-DM1,\u003c\/strong\u003e the most common adverse events were liver-related and blood-related:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eIncreased aspartate aminotransferase (AST) level, a marker of liver irritation: 50.2%\u003c\/li\u003e\n  \u003cli\u003eDecreased platelet count (thrombocytopenia, which raises bleeding risk): 49.8%\u003c\/li\u003e\n  \u003cli\u003eIncreased alanine aminotransferase (ALT) level, another liver marker: 45.3%\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eThe most concerning safety finding involved the lungs. The incidence of adjudicated drug-related \u003cstrong\u003einterstitial lung disease\u003c\/strong\u003e (inflammation and scarring of lung tissue, also called pneumonitis) was 9.6% (about 1 in 10 patients) with T-DXd versus 1.6% with T-DM1. Tragically, two patients in the T-DXd group died from interstitial lung disease. This is why the trial mandated chest CT monitoring at regular intervals, and why doctors must remain vigilant about new cough, fever, or breathing difficulty in patients receiving T-DXd.\u003c\/p\u003e\n\n\u003cp\u003eAdverse events of any grade leading to drug discontinuation occurred in 17.9% of patients taking T-DXd and 12.9% of those taking T-DM1. This higher discontinuation rate with T-DXd likely reflects both the gastrointestinal side effects and the lung toxicity monitoring.\u003c\/p\u003e\n\n\u003ch2 id=\"limitations\"\u003eStudy Limitations\u003c\/h2\u003e\n\n\u003cp\u003eEvery clinical trial has limits, and it is important to interpret these results accordingly. First, these are interim results at a median follow-up of about 30 months. Longer follow-up is still needed to confirm whether the early benefit in invasive disease-free survival translates into an overall survival advantage. The overall survival data so far (2.2% vs. 3.5% deaths; hazard ratio, 0.61; 95% CI, 0.34 to 1.10) are encouraging but not yet statistically significant.\u003c\/p\u003e\n\n\u003cp\u003eSecond, the trial was open-label, meaning patients and doctors knew which drug was administered. This can introduce bias, particularly in how side effects are reported, although the end points themselves were objective and assessed centrally where possible.\u003c\/p\u003e\n\n\u003cp\u003eThird, the brain metastasis results, while numerically favoring T-DXd (2.1% vs. 3.2%), did not reach statistical significance (hazard ratio, 0.64; 95% CI, 0.35 to 1.17). The confidence interval is wide, reflecting the small number of events (17 vs. 26). More follow-up may clarify whether T-DXd truly reduces brain metastases.\u003c\/p\u003e\n\n\u003cp\u003eFourth, the trial population was largely Asian (about 48%) and White (about 37-41%), with very few Black patients (2.7% vs. 1.6%). This limits how confidently the results can be generalized to all populations.\u003c\/p\u003e\n\n\u003cp\u003eFifth, these results apply only to the specific high-risk group studied: patients with HER2-positive disease who had residual invasive disease after neoadjuvant therapy, with either node-positive disease at surgery or inoperable disease at diagnosis. The findings do not apply to patients whose tumors completely disappeared before surgery, nor to patients with lower-risk disease.\u003c\/p\u003e\n\n\u003cp\u003eFinally, the trial was funded by the drug manufacturers (Daiichi Sankyo, in collaboration with AstraZeneca). AstraZeneca was not involved in trial design or data collection but did participate in data interpretation and manuscript review. Medical writers funded by Daiichi Sankyo drafted the manuscript under the authors' guidance. The authors vouch for the completeness and accuracy of the data.\u003c\/p\u003e\n\n\u003ch2 id=\"recommendations\"\u003eRecommendations for Patients\u003c\/h2\u003e\n\n\u003cp\u003eIf you or a loved one has HER2-positive early breast cancer and your pathology report after surgery shows residual invasive disease, these results are relevant to your treatment decisions. Here are some practical points to discuss with your oncology team:\u003c\/p\u003e\n\n\u003col\u003e\n  \u003cli\u003e\n\u003cstrong\u003eAsk about T-DXd as a post-surgery option.\u003c\/strong\u003e The DESTINY-Breast05 trial shows a 53% relative reduction in the risk of invasive disease or death compared with T-DM1 in high-risk patients. In absolute terms, about 8.7 more patients out of every 100 remained free of invasive disease at 3 years with T-DXd (92.4% vs. 83.7%).\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDiscuss your personal risk profile.\u003c\/strong\u003e The patients in this trial had high-risk features: inoperable disease at diagnosis or positive lymph nodes after neoadjuvant therapy. If you fit this profile, the benefit could be substantial. If your risk is lower, the balance of benefit and side effects may differ.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eUnderstand the lung risk.\u003c\/strong\u003e Interstitial lung disease occurred in about 1 in 10 patients taking T-DXd in this trial, and two patients died from it. Tell your doctor immediately about any new or worsening cough, shortness of breath, or fever while taking T-DXd. The trial used scheduled chest CT scans, so ask what monitoring plan your team recommends.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePlan for gastrointestinal side effects.\u003c\/strong\u003e Nausea affected 71.3% of T-DXd patients and vomiting affected 31.0%. Ask your care team about anti-nausea medications before you start treatment, not after symptoms begin.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eKnow that the two drugs cause different side effects.\u003c\/strong\u003e T-DM1 more often causes low platelet counts (49.8%) and elevated liver enzymes (about 45-50%), while T-DXd more often causes nausea, vomiting, constipation, and low neutrophil counts. Your medical history matters when choosing between them.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eKeep perspective on survival data.\u003c\/strong\u003e Overall survival results are not yet mature. The trend favors T-DXd (97.4% vs. 95.7% at 3 years), but this difference was not statistically significant. Longer follow-up from this trial will provide more definitive answers.\u003c\/li\u003e\n\u003c\/ol\u003e\n\n\u003cp\u003eThe decision between T-DXd and T-DM1 is a personal one that depends on your tumor characteristics, your medical history, and your tolerance for specific side effects. These results give patients and doctors a powerful new choice where previously there was only one standard option.\u003c\/p\u003e\n\n\u003c!-- ddn:faq:start --\u003e\n\u003ch2 id=\"ddn-faq\"\u003eFrequently Asked Questions\u003c\/h2\u003e\n\u003ch3\u003eWhat is HER2-positive breast cancer and why is residual disease after neoadjuvant therapy important?\u003c\/h3\u003e\n\u003cp\u003eAbout 1 in 5 breast cancers are HER2-positive, meaning cancer cells have too much HER2 protein, which promotes growth. Residual invasive disease means living cancer cells remain in the breast or lymph nodes after pre-surgery treatment. This indicates a higher risk of recurrence, especially if lymph nodes are involved.\u003c\/p\u003e\n\u003ch3\u003eWho was eligible for the DESTINY-Breast05 trial?\u003c\/h3\u003e\n\u003cp\u003ePatients had HER2-positive early breast cancer with residual invasive disease after neoadjuvant therapy. They also had high-risk features: either inoperable disease at diagnosis or operable disease with positive lymph nodes after neoadjuvant therapy. All had completed at least 9 weeks of taxane-based chemotherapy and HER2-targeted treatment.\u003c\/p\u003e\n\u003ch3\u003eHow well did trastuzumab deruxtecan (T-DXd) work compared with trastuzumab emtansine (T-DM1) in the trial?\u003c\/h3\u003e\n\u003cp\u003eIn the trial, T-DXd reduced the risk of invasive cancer returning or death by 53% compared with T-DM1. Three-year invasive disease-free survival was 92.4% with T-DXd versus 83.7% with T-DM1. This means about 92 out of 100 patients on T-DXd remained free of invasive disease at 3 years, versus about 84 out of 100 on T-DM1.\u003c\/p\u003e\n\u003ch3\u003eWhat is the risk of interstitial lung disease with T-DXd?\u003c\/h3\u003e\n\u003cp\u003eIn the trial, interstitial lung disease occurred in 9.6% of patients taking T-DXd versus 1.6% with T-DM1. Two patients in the T-DXd group died from it. Because of this risk, the trial used scheduled chest CT scans. Patients should tell their doctor immediately about any new cough, shortness of breath, or fever.\u003c\/p\u003e\n\u003ch3\u003eAre the overall survival results from the trial mature?\u003c\/h3\u003e\n\u003cp\u003eNo, overall survival data are still early. At the data cutoff, death occurred in 2.2% of T-DXd patients versus 3.5% with T-DM1, a difference that was not statistically significant. Three-year survival was 97.4% versus 95.7%. Longer follow-up is needed to confirm if the benefit translates into an overall survival advantage.\u003c\/p\u003e\n\u003ch3\u003eWhat should I discuss with my oncology team if I have residual disease after neoadjuvant therapy?\u003c\/h3\u003e\n\u003cp\u003eAsk whether T-DXd is a suitable post-surgery option, given your personal risk profile. Discuss the lung risk and monitoring plan, and plan for gastrointestinal side effects like nausea. Understand that T-DXd and T-DM1 have different side effect profiles, and your medical history matters. The decision is personal, based on tumor characteristics and tolerance for side effects.\u003c\/p\u003e\n\u003ch3\u003eShould I get a second opinion before choosing T-DXd versus T-DM1 for HER2-positive early breast cancer with residual disease after neoadjuvant therapy?\u003c\/h3\u003e\n\u003cp\u003eA second opinion can help you weigh the trade-offs shown in the DESTINY-Breast05 trial. T-DXd reduced the risk of invasive cancer returning or death by 53% compared with T-DM1, but it also caused more interstitial lung disease (9.6% vs. 1.6%), including two deaths. Your personal risk profile, medical history, and tolerance for side effects matter. An independent expert can review your pathology and imaging to confirm you fit the high-risk criteria and help you decide which option is right for you. Diagnostic Detectives Network provides independent expert second opinions.\u003c\/p\u003e\n\u003c!-- ddn:faq:end --\u003e\n\n\u003ch2 id=\"source\"\u003eSource Information\u003c\/h2\u003e\n\n\u003cp\u003e\u003cstrong\u003eOriginal article title:\u003c\/strong\u003e Trastuzumab Deruxtecan in Residual HER2-Positive Early Breast Cancer\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors:\u003c\/strong\u003e S. Loibl, Y.H. Park, Z. Shao, C.-S. Huang, C. Barrios, J. Abraham, A. Prat, N. Niikura, S.-A. Im, W. Li, H. Li, Y. Wang, H. Yao, S.-B. Kim, C. Geng, W. Rodriguez Pantigoso, F.J. Ramírez Godinez, C. Song, Y. Ching Chang, A. Antoniazzi, S.-C. Chen, Z. Li, Z. Nowecki, J. Lim, E. Mathias, Y. Sato, W. Lu, H. Abdel-Monem, M. Untch, and C.E. Geyer, Jr., for the DESTINY-Breast05 Trial Investigators\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003ePublication:\u003c\/strong\u003e \u003cem\u003eNew England Journal of Medicine\u003c\/em\u003e, February 26, 2026, volume 394, issue 9, pages 845-857. Published online December 10, 2025, and updated February 18, 2026.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDOI:\u003c\/strong\u003e 10.1056\/NEJMoa2514661\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eTrial registration:\u003c\/strong\u003e ClinicalTrials.gov number NCT04622319\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u003c\/strong\u003e Daiichi Sankyo, in collaboration with AstraZeneca\u003c\/p\u003e\n\u003cp\u003e\u003cem\u003eNote: This patient-friendly article is based on peer-reviewed research published in the New England Journal of Medicine. It is intended to help patients understand the study and should not replace medical advice from a qualified healthcare professional. Always discuss treatment decisions with your oncology team.\u003c\/em\u003e\u003c\/p\u003e","brand":"DiagnosticDetectives.Com","offers":[{"title":"Default Title","offer_id":47494458179740,"sku":null,"price":0.0,"currency_code":"RUB","in_stock":true}],"url":"https:\/\/diagnosticdetectives.ru\/products\/a-new-treatment-option-for-high-risk-her2-positive-early-breast-cancer-what-the-destiny-breast05-trial-means-for-patients","provider":"DiagnosticDetectives.Com","version":"1.0","type":"link"}