|Year : 2019 | Volume
| Issue : 4 | Page : 556-558
Trastuzumab deruxtecan: A quantum leap in HER2-positive breast cancer
Department of Medical Oncology, Cancer Institute (WIA), Chennai, Tamil Nadu, India
|Date of Submission||23-Dec-2019|
|Date of Decision||03-Jan-2020|
|Date of Acceptance||06-Jan-2020|
|Date of Web Publication||17-Feb-2020|
Dr. Manikandan Dhanushkodi
Department of Medical Oncology, Cancer Institute (WIA), 38 Sardar Patel Road, Chennai - 600 036, Tamil Nadu
Source of Support: None, Conflict of Interest: None
Docetaxel, trastuzumab, and pertuzumab, known as THP, is the preferred first-line treatment for HER2-positive advanced breast cancer, and the second-line drug of choice is trastuzumab emtansine. Most patients eventually develop resistance to systemic therapy. Trastuzumab deruxtecan, a novel HER2-targeted antibody drug conjugate, has shown to be promising in this subset. It is a HER2-targeted antibody drug conjugate structurally composed of humanized anti-HER2 monoclonal antibody, cleavable tetra-peptide-based liker, and a potent payload (topoisomerase 1 inhibitor: Exatecan). A phase 2 trial of heavily pretreated advanced HER2-positive breast cancer (median of six lines of prior therapy) showed an overall response of 61% and a median progression-free survival of 16 months. In December 2019, the Food and Drug Administration announced accelerated approval of trastuzumab deruxtecan for HER2-positive advanced breast cancer patients who were prior exposed to two or more lines of anti-HER2 therapy in a metastatic setting.
Keywords: Advanced breast cancer, HER2 positive, trastuzumab deruxtecan
|How to cite this article:|
Dhanushkodi M. Trastuzumab deruxtecan: A quantum leap in HER2-positive breast cancer. Indian J Med Paediatr Oncol 2019;40:556-8
|How to cite this URL:|
Dhanushkodi M. Trastuzumab deruxtecan: A quantum leap in HER2-positive breast cancer. Indian J Med Paediatr Oncol [serial online] 2019 [cited 2020 Apr 1];40:556-8. Available from: http://www.ijmpo.org/text.asp?2019/40/4/556/278515
| Introduction|| |
Docetaxel, trastuzumab, and pertuzumab, known as THP, is the preferred first-line treatment for HER2-positive advanced breast cancer and has shown a median overall survival (OS) of 4½ years. The second-line drug of choice is trastuzumab emtansine (TDM1). Resistance to anti-HER2 therapy develops due to various factors including loss of HER2 expression, downregulation of HER2 expression, heterogeneous HER2 expression, and receptor mutation.
There is no standard third-line therapy for patients who progress after exposure to TDM1. Recently, tucatinib  in combination with trastuzumab and capecitabine has shown to be promising in this subset, especially in those with brain metastasis. Trastuzumab deruxtecan, a novel HER2-targeted antibody drug conjugate, has shown to be promising in patients with heavily pretreated HER2-positive advanced breast cancer.
| Mechanism of Action|| |
Trastuzumab deruxtecan is a HER2-targeted antibody drug conjugate structurally composed of humanized anti-HER2 monoclonal antibody, cleavable tetra-peptide-based liker, and a potent payload (topoisomerase 1 inhibitor: Exatecan). The monoclonal antibody targets HER2-expressing tumor cells and internalizes the payload. The lysosomes cleave the linker, causing the payload to inhibit topoisomerase 1, and cause tumor cell death.
| Landmark Trials|| |
Trastuzumab deruxtecan (DS-8201a) significantly suppressed tumor growth in immunocompetent mouse models with human HER2-expressing cell lines. It enhanced antitumor immunity by increased expression of dendritic cell markers, augmenting the expression of major histocompatibility complex Class I in tumor cells, and rejection of rechallenged tumor cells by adaptive immune cells.
This dose-expansion study  included 115 patients with heavily pretreated (seven prior lines) HER2-positive advanced breast cancer. The overall response rate was 60%, the median time to response was 1.5 months, and the median progression-free survival (PFS) and OS were 22 months and not reached, respectively. The recommended phase 2 dose was 5.4 mg/kg or 6.4 mg/kg.
The Destiny-Breast01 trial  included 184 patients with a median age of 55 years, 38% of Asian ethnicity with a median tumor size of 5.5 cm. This cohort included a heavily pretreated subset with a median of six lines of prior therapy (range: 2–27). All patients were prior exposed to trastuzumab and TDM1 and 66% had received pertuzumab. The overall response rate was 61%, with a median PFS of 16 months.
The Destiny-Breast02 trial will assess the efficacy and safety of trastuzumab deruxtecan versus investigators' choice in patients who progress on TDM1. The Destiny-Breast03 trial will assess the efficacy and safety of trastuzumab deruxtecan versus TDM1.
| Advantages|| |
The remarkable response of trastuzumab deruxtecan is due to the highly potent payload (topoisomerase 1 inhibitor: Exatecan), high drug-to-antibody ratio (8 with trastuzumab deruxtecan and 3.5 with TDM1), stable linker payload in circulation, tumor-selective cleavable linker, and payload-induced bystander effect.
| Novelty|| |
Trastuzumab deruxtecan has also shown activity in patients with low HER2-expressing (immunohistochemistry <3+ and negative in situ hybridization) breast cancer.
| Approval|| |
In August 2017, the Food and Drug Administration (FDA) granted breakthrough therapy designation to trastuzumab deruxtecan for the treatment of patients with advanced HER2-positive breast cancer previously treated with trastuzumab and pertuzumab and whose disease progressed after TDM1.
In December 2019, the FDA granted accelerated approval for trastuzumab deruxtecan for the treatment of adults with unresectable or metastatic HER2-positive breast cancer who had received two or more lines of anti-HER2-based regimen in a metastatic setting.
| Dose|| |
The recommended dose is 5.4 mg/kg every 3 weeks until disease progression/unacceptable toxicity.
| Side Effects|| |
The grade 3 or 4 adverse effects are neutropenia (20%), anemia (9%), and nausea (8%). The potential serious adverse effect is interstitial lung disease (ILD) (Grade 1–2: 11%; Grade 3–4: 0.5%; and Grade 5: 2%).
| Monitoring|| |
Patients need to be monitored closely for fever, cough, or dyspnea for early detection of ILD. Patients who develop ILD should be managed with steroids, dose reductions, or discontinuation.
| Other HER2-Positive Cancers|| |
Trastuzumab deruxtecan is also being evaluated in HER2-positive gastro-esophageal cancer, gastric cancer, colon cancer, and HER2 mutated non-small cell lung cancer.
| Newer Anti-HER2 Drugs in Pipeline|| |
- Tucatinib in combination with trastuzumab and capecitabine has shown a survival advantage in pretreated HER2-positive breast cancer, especially those with brain metastasis 
- Neratinib in combination with capecitabine has shown improved PFS as compared to lapatinib with capecitabine in pretreated HER2-positive advanced breast cancer 
- Margetuximab and chemotherapy improves PFS as compared to trastuzumab and chemotherapy in pretreated HER2-positive advanced breast cancer.
| Conclusion|| |
Trastuzumab deruxtecan is a novel antibody drug conjugate with impressive and durable response in heavily pretreated HER2-positive advanced breast cancer.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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