ENHERTU (fam-trastuzumab deruxtecan-nxki) Continues to Demonstrate Durable Responses with New Data From DESTINY-Breast01 in HER2-positive Metastatic Breast Cancer

Rhea-AI Summary

AstraZeneca and Daiichi Sankyo presented updated results from the DESTINY-Breast01 trial for ENHERTU (fam-trastuzumab deruxtecan-nxki), showing continued efficacy in HER2-positive metastatic breast cancer patients. With a median follow-up of 20.5 months, the trial indicated a 61.4% objective response rate (ORR) and a median duration of response of 20.8 months. The median progression-free survival was 19.4 months, and 74% of patients remained alive at 18 months. The treatment demonstrated consistent safety profiles, though 18.5% discontinued due to adverse events. ENHERTU is approved in the US and Japan.

Positive

• 61.4% objective response rate (ORR) in updated trial results.
• Median duration of response increased to 20.8 months.
• Median progression-free survival (PFS) reported at 19.4 months.
• 74% overall survival (OS) rate at 18 months.

Negative

• 18.5% of patients discontinued treatment due to adverse events.
• New cases of interstitial lung disease (ILD) including one death reported.

WILMINGTON, Del.--(BUSINESS WIRE)--Updated results from the positive DESTINY-Breast01 Phase II trial showed AstraZeneca and Daiichi Sankyo Company, Limited (Daiichi Sankyo)’s ENHERTU^® (fam-trastuzumab deruxtecan-nxki) continued to demonstrate impressive efficacy and durable responses in patients with HER2-positive metastatic breast cancer following two or more prior HER2-based regimens.

The updated data were presented in a Spotlight Poster Discussion at the 2020 San Antonio Breast Cancer Symposium (SABCS).

With a median duration of follow-up of 20.5 months, patients treated with ENHERTU (5.4 mg/kg) achieved an objective response rate (ORR) of 61.4% and a median duration of response (DoR) of 20.8 months. The median progression-free survival (PFS) was 19.4 months. In an exploratory landmark analysis of overall survival (OS), evaluated at 35% maturity, an estimated 74% of patients remained alive at 18 months.

In the previous analysis at 11.1 months of follow-up, an ORR of 60.9% was seen with a median DoR of 14.8 months and median PFS of 16.4 months. Additional trials are ongoing to confirm the results seen in DESTINY-Breast01.

Approximately one in five patients with breast cancer are considered HER2 positive, which is associated with aggressive disease, high recurrence rate, and increased mortality.^1,2

Shanu Modi, MD, Breast Medical Oncologist, Memorial Sloan Kettering Cancer Center and principal investigator in the DESTINY-Breast01 trial, said: “These longer-term data from the DESTINY-Breast01 trial further highlight the role that this treatment option may have in changing clinical outcomes for patients with previously treated HER2-positive metastatic breast cancer. It is important that we are able to offer patients therapy like this which provides a meaningful clinical benefit, as historically there have been few therapies that were able to do that in this patient population.”

José Baselga, Executive Vice President, Oncology R&D, said: “These results reinforce the transformational potential of ENHERTU in patients with previously treated HER2-positive metastatic breast cancer. With a median duration of response of greater than twenty months, the updated results of DESTINY-Breast01 are unprecedented. We look forward to further confirming the DESTINY-Breast01 findings with results from our Phase III development program for ENHERTU.”

Antoine Yver, Executive Vice President and Global Head, Oncology R&D, Daiichi Sankyo, said: “The updated findings illustrate the practice-changing potential for ENHERTU to become a long-term treatment option for patients with previously treated HER2-positive metastatic breast cancer. The duration of response and long-term safety profile further validate that our proprietary DXd antibody drug conjugate technology delivers effective and durable treatment.”

Summary of updated efficacy results from DESTINY-Breast01

	As of Aug 1 2019 (n=184)i	As of Jun 8 2020 (n=184)ii
Median duration of follow-up	11.1 months (0.7-19.9)	20.5 months (0.7-31.4)
Patients remaining on treatment	42.9% (n=79)	20.1% (n=37)
Confirmed ORR by ICR [95% CI]iii,iv	60.9% [53.4-68.0] (n=112)	61.4% [54.0-68.5] (n=113)
Complete response	6.0% (n=11)	6.5% (n=12)
Partial response	54.9% (n=101)	54.9% (n=101)
Stable disease	36.4% (n=67)	35.9% (n=66)
Progressive disease	1.6% (n=3)	1.6% (n=3)
Median duration of response (95% CI)	14.8 months (13.8-16.9)	20.8 months (15.0-NE)v
Median PFS (95% CI)vi	16.4 months (12.7-NE)	19.4 months (14.1-NE)
Median OS (95% CI)vii	NE (NE-NE)	24.6 months (23.1-NE)
Estimated OS at 12 months (95% CI)	86.2% (79.8-90.7)	85% (79-90)
Estimated OS at 18 months (95% CI)	--	74% (67-80)
i Data from the 1 August 2019 cut-off were presented at the 2019 SABCS and published in The New England Journal of Medicine.
ii As of data cut-off, 20.1% of patients remained on treatment with Enhertu
iii ICR, independent central review
iv CI, confidence interval
v NE, not estimable
vi 114 patients (62.0%) were censored at time of analysis
vii OS was estimated at 35% maturity, with 119 patients (64.7%) censored and only 17 patients at risk at 24 months; additional follow-up is required for more mature OS data

The overall safety and tolerability profiles of ENHERTU were consistent with what has been previously reported, with few additional treatment discontinuations due to adverse events with longer treatment duration. In the updated analysis, 18.5% of patients discontinued treatment due to adverse events compared to 15.2% in the previous analysis. Most cases of interstitial lung disease (ILD) or pneumonitis occurred during the first 12 months of treatment and the results suggest the risk of developing ILD or pneumonitis toxicity is not related to cumulative treatment with ENHERTU. There were three new cases of treatment-related ILD reported, as determined by an independent adjudication committee, including one Grade 1, one Grade 2 and one death (Grade 5). Two potential cases were pending adjudication at data cut-off. Continued attention to monitoring to identify pulmonary symptoms and ensure early intervention is warranted.

ENHERTU was approved in the US and Japan for the treatment of HER2-positive, unresectable or metastatic breast cancer following two or more prior anti-HER2 based regimens in the metastatic setting based on the earlier results from the DESTINY-Breast01 trial. In the US, ENHERTU was approved under FDA Accelerated Approval and confirmatory trials are underway.

Several ongoing randomized Phase III trials are further testing ENHERTU in patients with HER2-expressing metastatic breast cancer. These trials include DESTINY-Breast02, which is evaluating ENHERTU as a 3rd-line treatment for patients with HER2-positive metastatic breast cancer and DESTINY-Breast03, which is testing ENHERTU as a 2nd-line treatment for these patients. DESTINY-Breast04 is investigating ENHERTU in patients with metastatic breast cancer and low expressions of HER2.

FDA-Approved Indication for ENHERTU

ENHERTU is a HER2-directed antibody and topoisomerase inhibitor conjugate indicated for the treatment of adult patients with unresectable or metastatic HER2-positive breast cancer who have received two or more prior anti-HER2-based regimens in the metastatic setting.

This indication is approved under accelerated approval based on tumor response rate and duration of response. Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial.

IMPORTANT SAFETY INFORMATION

Contraindications

None.

WARNING: INTERSTITIAL LUNG DISEASE and EMBRYO-FETAL TOXICITY Interstitial lung disease (ILD) and pneumonitis, including fatal cases, have been reported with ENHERTU. Monitor for and promptly investigate signs and symptoms including cough, dyspnea, fever, and other new or worsening respiratory symptoms. Permanently discontinue ENHERTU in all patients with Grade 2 or higher ILD/pneumonitis. Advise patients of the risk and to immediately report symptoms. Exposure to ENHERTU during pregnancy can cause embryo-fetal harm. Advise patients of these risks and the need for effective contraception.

WARNINGS AND PRECAUTIONS

Interstitial Lung Disease / Pneumonitis

Severe, life-threatening, or fatal interstitial lung disease (ILD), including pneumonitis, can occur in patients treated with ENHERTU. In clinical studies, of the 234 patients with unresectable or metastatic HER2-positive breast cancer treated with ENHERTU, ILD occurred in 9% of patients. Fatal outcomes due to ILD and/or pneumonitis occurred in 2.6% of patients treated with ENHERTU. Median time to first onset was 4.1 months (range: 1.2 to 8.3).

Advise patients to immediately report cough, dyspnea, fever, and/or any new or worsening respiratory symptoms. Monitor patients for signs and symptoms of ILD. Promptly investigate evidence of ILD. Evaluate patients with suspected ILD by radiographic imaging. Consider consultation with a pulmonologist. For asymptomatic ILD/pneumonitis (Grade 1), interrupt ENHERTU until resolved to Grade 0, then if resolved in ≤28 days from date of onset, maintain dose. If resolved in >28 days from date of onset, reduce dose one level. Consider corticosteroid treatment as soon as ILD/pneumonitis is suspected (e.g., ≥0.5 mg/kg prednisolone or equivalent). For symptomatic ILD/pneumonitis (Grade 2 or greater), permanently discontinue ENHERTU. Promptly initiate corticosteroid treatment as soon as ILD/pneumonitis is suspected (e.g., ≥1 mg/kg prednisolone or equivalent). Upon improvement, follow by gradual taper (e.g., 4 weeks).

Neutropenia

Severe neutropenia, including febrile neutropenia, can occur in patients treated with ENHERTU. Of the 234 patients with unresectable or metastatic HER2-positive breast cancer who received ENHERTU, a decrease in neutrophil count was reported in 30% of patients and 16% had Grade 3 or 4 events. Median time to first onset was 1.4 months (range: 0.3 to 18.2). Febrile neutropenia was reported in 1.7% of patients.

Monitor complete blood counts prior to initiation of ENHERTU and prior to each dose, and as clinically indicated. Based on the severity of neutropenia, ENHERTU may require dose interruption or reduction. For Grade 3 neutropenia (Absolute Neutrophil Count [ANC] <1.0 to 0.5 x 109/L) interrupt ENHERTU until resolved to Grade 2 or less, then maintain dose. For Grade 4 neutropenia (ANC <0.5 x 109/L) interrupt ENHERTU until resolved to Grade 2 or less. Reduce dose by one level. For febrile neutropenia (ANC <1.0 x 109/L and temperature >38.3ºC or a sustained temperature of ≥38ºC for more than 1 hour), interrupt ENHERTU until resolved. Reduce dose by one level.

Left Ventricular Dysfunction

Patients treated with ENHERTU may be at increased risk of developing left ventricular dysfunction. Left ventricular ejection fraction (LVEF) decrease has been observed with anti-HER2 therapies, including ENHERTU. In the 234 patients with unresectable or metastatic HER2-positive breast cancer who received ENHERTU, two cases (0.9%) of asymptomatic LVEF decrease were reported. Treatment with ENHERTU has not been studied in patients with a history of clinically significant cardiac disease or LVEF <50% prior to initiation of treatment.

Assess LVEF prior to initiation of ENHERTU and at regular intervals during treatment as clinically indicated. Manage LVEF decrease through treatment interruption. Permanently discontinue ENHERTU if LVEF of <40% or absolute decrease from baseline of >20% is confirmed. When LVEF is >45% and absolute decrease from baseline is 10-20%, continue treatment with ENHERTU. When LVEF is 40-45% and absolute decrease from baseline is <10%, continue treatment with ENHERTU and repeat LVEF assessment within 3 weeks. When LVEF is 40-45% and absolute decrease from baseline is 10-20%, interrupt ENHERTU and repeat LVEF assessment within 3 weeks. If LVEF has not recovered to within 10% from baseline, permanently discontinue ENHERTU. If LVEF recovers to within 10% from baseline, resume treatment with ENHERTU at the same dose. When LVEF is <40% or absolute decrease from baseline is >20%, interrupt ENHERTU and repeat LVEF assessment within 3 weeks. If LVEF of <40% or absolute decrease from baseline of >20% is confirmed, permanently discontinue ENHERTU. Permanently discontinue ENHERTU in patients with symptomatic congestive heart failure.

Embryo-Fetal Toxicity

ENHERTU can cause fetal harm when administered to a pregnant woman. Advise patients of the potential risks to a fetus. Verify the pregnancy status of females of reproductive potential prior to the initiation of ENHERTU. Advise females of reproductive potential to use effective contraception during treatment and for at least 7 months following the last dose of ENHERTU. Advise male patients with female partners of reproductive potential to use effective contraception during treatment with ENHERTU and for at least 4 months after the last dose of ENHERTU.

Adverse Reactions

The safety of ENHERTU was evaluated in a pooled analysis of 234 patients with unresectable or metastatic HER2-positive breast cancer who received at least one dose of ENHERTU 5.4 mg/kg in DESTINY-Breast01 and Study DS8201-A-J101. ENHERTU was administered by intravenous infusion once every three weeks. The median duration of treatment was 7 months (range: 0.7 to 31).

Serious adverse reactions occurred in 20% of patients receiving ENHERTU. Serious adverse reactions in >1% of patients who received ENHERTU were interstitial lung disease, pneumonia, vomiting, nausea, cellulitis, hypokalemia, and intestinal obstruction. Fatalities due to adverse reactions occurred in 4.3% of patients including interstitial lung disease (2.6%), and the following events occurred in one patient each (0.4%): acute hepatic failure/acute kidney injury, general physical health deterioration, pneumonia, and hemorrhagic shock.

ENHERTU was permanently discontinued in 9% of patients, of which ILD accounted for 6%. Dose interruptions due to adverse reactions occurred in 33% of patients treated with ENHERTU. The most frequent adverse reactions (>2%) associated with dose interruption were neutropenia, anemia, thrombocytopenia, leukopenia, upper respiratory tract infection, fatigue, nausea, and ILD. Dose reductions occurred in 18% of patients treated with ENHERTU. The most frequent adverse reactions (>2%) associated with dose reduction were fatigue, nausea, and neutropenia.

The most common adverse reactions (frequency ≥20%) were nausea (79%), fatigue (59%), vomiting (47%), alopecia (46%), constipation (35%), decreased appetite (32%), anemia (31%), neutropenia (29%), diarrhea (29%), leukopenia (22%), cough (20%), and thrombocytopenia (20%).

Use in Specific Populations

• Pregnancy: ENHERTU can cause fetal harm when administered to a pregnant woman. Advise patients of the potential risks to a fetus. There are clinical considerations if ENHERTU is used in pregnant women, or if a patient becomes pregnant within 7 months following the last dose of ENHERTU.
• Lactation: There are no data regarding the presence of ENHERTU in human milk, the effects on the breastfed child, or the effects on milk production. Because of the potential for serious adverse reactions in a breastfed child, advise women not to breastfeed during treatment with ENHERTU and for 7 months after the last dose.
• Females and Males of Reproductive Potential: Pregnancy testing: Verify pregnancy status of females of reproductive potential prior to initiation of ENHERTU. Contraception: Females: ENHERTU can cause fetal harm when administered to a pregnant woman. Advise females of reproductive potential to use effective contraception during treatment with ENHERTU and for at least 7 months following the last dose. Males: Advise male patients with female partners of reproductive potential to use effective contraception during treatment with ENHERTU and for at least 4 months following the last dose. Infertility: ENHERTU may impair male reproductive function and fertility.
• Pediatric Use: Safety and effectiveness of ENHERTU have not been established in pediatric patients.
• Geriatric Use: Of the 234 patients with HER2-positive breast cancer treated with ENHERTU 5.4 mg/kg, 26% were ≥65 years and 5% were ≥75 years. No overall differences in efficacy were observed between patients ≥65 years of age compared to younger patients. There was a higher incidence of Grade 3-4 adverse reactions observed in patients aged ≥65 years (53%) as compared to younger patients (42%).
• Hepatic Impairment: In patients with moderate hepatic impairment, due to potentially increased exposure, closely monitor for increased toxicities related to the topoisomerase inhibitor.

To report SUSPECTED ADVERSE REACTIONS, contact Daiichi Sankyo, Inc. at 1-877-437-7763 or FDA at 1-800-FDA-1088 or fda.gov/medwatch.

Please see accompanying full Prescribing Information, including Boxed WARNINGS, and Medication Guide.

Notes

HER2-positive breast cancer

In women, breast cancer is the most common cancer and one of the most common causes of cancer mortality worldwide; there were an estimated 2.1 million new cases of female breast cancer diagnosed in 2018.^3,4 Breast cancer occurs mainly in women, but in rare cases it occurs in men too.⁵

HER2 is a tyrosine kinase receptor growth-promoting protein expressed on the surface of many types of tumors, including gastric, breast and lung cancers. HER2 overexpression is associated with a specific HER2 gene alteration known as HER2 amplification and is often associated with aggressive disease and poorer prognosis.⁶ Approximately one in five patients with breast cancer are considered HER2 positive.²

DESTINY-Breast01

DESTINY-Breast01 is a pivotal Phase II, single-arm, open-label, global, multicenter, two-part trial evaluating the safety and efficacy of ENHERTU in patients with HER2-positive unresectable and/or metastatic breast cancer previously treated with trastuzumab emtansine. The primary endpoint of the trial is ORR, as determined by ICR. Secondary objectives include DoR, disease control rate, clinical benefit rate, PFS and OS.

ENHERTU

ENHERTU (fam-trastuzumab deruxtecan-nxki) is a HER2-directed antibody drug conjugate (ADC). ENHERTU is the lead ADC in the oncology portfolio of Daiichi Sankyo and the most advanced program in AstraZeneca’s ADC scientific platform.

ADCs are targeted cancer medicines that deliver cytotoxic chemotherapy (“payload”) to cancer cells via a linker attached to a monoclonal antibody that binds to a specific target expressed on cancer cells. ENHERTU is comprised of a HER2 monoclonal antibody attached to a topoisomerase I inhibitor payload by a tetrapeptide-based linker.

ENHERTU (5.4mg/kg) is approved in the US and Japan for the treatment of adult patients with unresectable or metastatic HER2-positive breast cancer who have received two or more prior anti-HER2 based regimens in the metastatic setting based on the DESTINY-Breast01 trial. ENHERTU (6.4mg/kg) is approved in Japan for patients with HER2-positive unresectable advanced or recurrent gastric cancer that progressed after chemotherapy.

ENHERTU clinical development

A comprehensive development program is underway globally, with nine registrational trials evaluating the efficacy and safety of trastuzumab deruxtecan monotherapy across multiple HER2 cancers, including breast, gastric and lung cancers. Trials in combination with other anticancer treatments, such as immunotherapy, are also underway.

In October 2020, ENHERTU was granted Priority Review from the US Food and Drug Administration for the treatment of patients with HER2-positive metastatic gastric or gastroesophageal junction (GEJ) adenocarcinoma. In May 2020, ENHERTU received a Breakthrough Therapy Designation (BTD) and Orphan Drug Designation (ODD) for gastric cancer, including GEJ adenocarcinoma.

In July 2020, The European Medicines Agency’s Committee for Medicinal Products for Human Use granted accelerated assessment for the treatment of adults with unresectable or metastatic HER2 positive breast cancer who have received two or more prior anti-HER2 based regimens.

In May 2020, ENHERTU also received a BTD for the treatment of patients with metastatic non-small cell lung cancer whose tumors have a HER2 mutation and with disease progression on or after platinum-based therapy. ENHERTU is not approved in the US for gastric or lung cancer.

Collaboration between AstraZeneca and Daiichi Sankyo

AstraZeneca and Daiichi Sankyo entered into a global collaboration to jointly develop and commercialize fam-trastuzumab deruxtecan-nxki (a HER2-directed ADC) in March 2019, and datopotamab deruxtecan (DS-1062; a TROP2-directed ADC) in July 2020, except in Japan where Daiichi Sankyo maintains exclusive rights. Daiichi Sankyo is responsible for manufacturing and supply of fam-trastuzumab deruxtecan-nxki and datopotamab deruxtecan.

AstraZeneca in breast cancer

Driven by a growing understanding of breast cancer biology, AstraZeneca is starting to challenge, and redefine, the current clinical paradigm for how breast cancer is classified and treated to deliver even more effective treatments to patients in need – with the bold ambition to one day eliminate breast cancer as a cause of death.

AstraZeneca has a comprehensive portfolio of approved and promising compounds in development that leverage different mechanisms of action to address the biologically diverse breast cancer tumor environment. AstraZeneca aims to continue to transform outcomes for HR-positive breast cancer with foundational medicines fulvestrant and goserelin and the next-generation SERD and potential new medicine AZD9833. PARP inhibitor, olaparib is a targeted treatment option for metastatic breast cancer patients with an inherited BRCA mutation. AstraZeneca with MSD (Merck & Co., Inc. in the US and Canada) continue to research olaparib in metastatic breast cancer patients with an inherited BRCA mutation, and are exploring new opportunities to treat these patients earlier in their disease state. Building on the first approval of ENHERTU, a HER2-directed antibody-drug conjugate, in previously treated HER2-positive metastatic breast cancer, AstraZeneca and Daiichi Sankyo are exploring its potential in earlier lines of treatment and in new breast cancer settings. To bring much needed treatment options to patients with triple-negative breast cancer, an aggressive form of breast cancer, AstraZeneca is testing immunotherapy durvalumab in combination with other oncology medicines, including olaparib and ENHERTU, investigating the potential of AKT kinase inhibitor, capivasertib, in combination with chemotherapy, and collaborating with Daiichi Sankyo to explore the potential of TROP2-directed ADC, datopotamab deruxtecan (DS-1062).

AstraZeneca in oncology

AstraZeneca has a deep-rooted heritage in oncology and offers a quickly growing portfolio of new medicines that has the potential to transform patients’ lives and the Company’s future. With seven new medicines launched between 2014 and 2020, and a broad pipeline of small molecules and biologics in development, the Company is committed to advance oncology as a key growth driver for AstraZeneca focused on lung, ovarian, breast and blood cancers.

By harnessing the power of four scientific platforms – Immuno-Oncology, Tumor Drivers and Resistance, DNA Damage Response and Antibody Drug Conjugates – and by championing the development of personalized combinations, AstraZeneca has the vision to redefine cancer treatment and, one day, eliminate cancer as a cause of death.

AstraZeneca

AstraZeneca is a global, science-led biopharmaceutical company that focuses on the discovery, development and commercialization of prescription medicines, primarily for the treatment of diseases in three therapy areas - Oncology, Cardiovascular, Renal & Metabolism and Respiratory & Immunology. AstraZeneca operates in over 100 countries and its innovative medicines are used by millions of patients worldwide. For more information, please visit www.astrazeneca-us.com and follow us on Twitter @AstraZenecaUS.

References

1. Tandon A, et al. HER-2/neu oncogene protein and prognosis in breast cancer. J Clin Oncol. 1989;7(8):1120-8.
2. Mitri Z, et al. The HER2 Receptor in Breast Cancer: Pathophysiology, Clinical Use, and New Advances in Therapy. Chemother ResPrac. 2012 (743193).
3. GLOBOCAN 2018. Breast Cancer Fact Sheet. World Health Organization. Accessed: December 2020.
4. IARC WHO 2018. Latest global cancer data. Accessed: December 2020
5. Yalaza, M., Inan, A., & Bozer, M. Male Breast Cancer. Eur J Breast Health. 2016;12(1), 1–8.
6. Iqbal N, et al. Human Epidermal Growth Factor Receptor 2 (HER2) in Cancers: Overexpression and Therapeutic Implications. Mol Biol Int. 2014;852748.

Dr. Modi has provided consulting/advisory services for Daiichi Sankyo.

US-48296 | 12/20