Samsung Bioepis Announces Four-year Follow-up Data for Biosimilar ONTRUZANT® (trastuzumab-dttb) in Early or Locally Advanced HER2-positive Breast Cancer

INCHEON, Korea

Samsung Bioepis Co., Ltd. announced today that four-year follow-up results of the Phase 3 study for ONTRUZANT^®, a biosimilar of the reference medicine HERCEPTIN^®1 (trastuzumab), will be presented at the ASCO20 Virtual Scientific Program organized by the American Society of Clinical Oncology (ASCO), which will be held from May 29-31, 2020.

The four-year follow-up data is part of the ongoing follow-up study to assess cardiac safety and survival outcome in a subgroup of patients from the Phase 3 study who completed neoadjuvant and adjuvant therapy for one year. Among 875 patients from the Phase 3 study, a total of 367 patients were enrolled in the extension study, with a median follow-up of 53 months. During the follow-up period, cardiac safety was comparable between ONTRUZANT^® (SB3) and reference trastuzumab (TRZ), with no occurrence of symptomatic congestive heart failure (CHF) and a very low incidence of asymptomatic significant left ventricular ejection fraction (LVEF) decrease (SB3, n=1; TRZ, n=2). Four-year event-free survival (EFS) rates and overall survival (OS) rates were also comparable between ONTRUZANT^® and reference trastuzumab (EFS: SB3 83.4% vs. TRZ 80.7%; OS: SB3 94.4% vs. TRZ 89.6%).

“The four-year follow-up results further support comparable safety and efficacy profiles of ONTRUZANT to reference trastuzumab,” said Seongwon Han, Vice President, Medical & Lifecycle Safety Lead, Samsung Bioepis. He continued, “We hope these findings on long-term safety and efficacy help build confidence in the use of biosimilars for prescribers and patients.”

The poster of this study will be presented at the ASCO20 Virtual Scientific Program, as follows:

• [578] Four-year Follow-up of a Phase III Study Comparing SB3 (Trastuzumab Biosimilar) and Reference Trastuzumab in HER2-positive Early or Locally Advanced Breast Cancer in Neoadjuvant Setting ‒ Poster session (Poster 70) * Poster sessions will be available on demand beginning Friday, May 29, 2020 at 8:00 a.m. ET

About SB3 (ONTRUZANT^®) Follow-up Study (SB3-G31-BC-E)
Among 875 patients who participated in the Phase 3 study of SB3, a total of 367 patients (SB3, n=186; TRZ, n=181) were enrolled in a five-year follow-up study. The aim of this follow-up study was to observe the incidence of symptomatic congestive heart failure (CHF), asymptomatic significant left ventricular ejection fraction (LVEF) decrease, incidence of other cardiac events, event-free survival (EFS), and overall survival (OS). The median follow-up duration from initiation of the Phase 3 study was 53 months.

During the follow-up period, incidence of asymptomatic significant LVEF decrease was comparable between SB3 and reference trastuzumab (SB3, n=1; TRZ, n=2), with all patients recovering with LVEF who reported 50% or above. No symptomatic CHF, cardiac death, or other significant cardiac condition occurred in either group during the follow-up period.

Four-year EFS rates were 83.4% for SB3 and 80.7% for reference trastuzumab (HR 0.77, 95% CI 0.47-1.27), while four-year OS rates were 94.4% for SB3 and 89.6% for reference trastuzumab (HR 0.53, 95% CI 0.24-1.16).

Within the group of patients who received reference trastuzumab, the patients exposed to at least one vial from the reference trastuzumab lots with expiry dates from August 2018 to December 2019 during neoadjuvant period showing lower (drifted) levels of antibody dependent cellular cytotoxicity (ADCC) were classified as the “drifted TRZ group,” and the remaining patients who were not exposed to any vials from the reference trastuzumab lots with lower levels of ADCC were classified as the “non-drifted TRZ group.” In an ad-hoc analysis, there was no difference observed in EFS (HR 1.60, 95% CI, 0.58-4.40, p=0.362) and OS (HR 0.97 95% CI, 0.11-8.50, p=0.975) between SB3 and non-drifted TRZ group. There was a difference observed in EFS (HR 5.50 95% CI, 1.81-16.65, p=0.003) and OS (HR 15.35 95% CI, 1.78-132.69, p=0.013) between drifted TRZ and non-drifted TRZ group.

About ONTRUZANT^® (trastuzumab-dttb)
ONTRUZANT^® is indicated for adjuvant treatment of HER2-overexpressing node-positive or node-negative (ER/PR-negative or with one high-risk feature*) breast cancer:

• As part of a treatment regimen containing doxorubicin, cyclophosphamide and either paclitaxel or docetaxel
• As part of a treatment regimen with docetaxel and carboplatin
• As a single agent following multi-modality anthracycline-based therapy

Select patients for therapy based on an FDA-approved companion diagnostic for a trastuzumab product
* High-risk is defined as ER/PR positive with one of the following features: tumor size >2 cm, age <35 years, or tumor grade 2 or 3.

ONTRUZANT^® is indicated:

• In combination with paclitaxel for the first line treatment of HER2-overexpressing metastatic breast cancer
• As a single agent for treatment of HER2-overexpressing breast cancer in patients who have received one or more chemotherapy regimens for metastatic disease

Select patients for therapy based on an FDA-approved companion diagnostic for a trastuzumab product

ONTRUZANT^® is indicated, in combination with cisplatin and capecitabine or 5-fluorouracil, for the treatment of patients with HER2 overexpressing metastatic gastric or gastroesophageal junction adenocarcinoma, who have not received prior treatment for metastatic disease.

Select patients for therapy based on an FDA-approved companion diagnostic for a trastuzumab product.

Select Important Safety Information

Cardiomyopathy

• Administration of ONTRUZANT^® can result in sub-clinical and clinical cardiac failure
• Evaluate left ventricular function in all patients prior to and during treatment with ONTRUZANT^®. Discontinue ONTRUZANT^® treatment in patients receiving adjuvant therapy and withhold ONTRUZANT^® in patients with metastatic disease for clinically significant decrease in left ventricular function

Infusion Reactions; Pulmonary Toxicity

• Administration of ONTRUZANT^® can result in serious and fatal infusion reactions and pulmonary toxicity. Symptoms usually occur during or within 24 hours of administration. Interrupt ONTRUZANT^® infusion for dyspnea or clinically significant hypotension. Monitor patients until symptoms completely resolve. Discontinue ONTRUZANT^® for anaphylaxis, angioedema, interstitial pneumonitis, or acute respiratory distress syndrome

Embryo-Fetal Toxicity

• Exposure to ONTRUZANT^® during pregnancy can result in oligohydramnios and oligohydramnios sequence manifesting as pulmonary hypoplasia, skeletal abnormalities, and neonatal death. Advise patients of these risks and the need for effective contraception

Exacerbation of Chemotherapy-Induced Neutropenia

• In randomized, controlled clinical trials, the per-patient incidences of NCI-CTC Grade 3-4 neutropenia and of febrile neutropenia were higher in patients receiving trastuzumab products in combination with myelosuppressive chemotherapy as compared to those who received chemotherapy alone. The incidence of septic death was similar among patients who received trastuzumab and those who did not

Most Common Adverse Reactions

• The most common adverse reactions for trastuzumab products in breast cancer were fever, nausea, vomiting, infusion reactions, diarrhea, infections, increased cough, headache, fatigue, dyspnea, rash, neutropenia, anemia, and myalgia
• The most common adverse reactions for trastuzumab products in metastatic gastric cancer were neutropenia, diarrhea, fatigue, anemia, stomatitis, weight loss, upper respiratory tract infections, fever, thrombocytopenia, mucosal inflammation, nasopharyngitis, and dysgeusia

These are not all of the risks associated with ONTRUZANT^®. For additional information on ONTRUZANT^® indications, as well as Important Safety Information related to its use, including Boxed WARNINGS, please see the ONTRUZANT^® Prescribing Information HERE.

About Samsung Bioepis Co., Ltd.

Established in 2012, Samsung Bioepis is a biopharmaceutical company committed to realizing healthcare that is accessible to everyone. Through innovations in product development and a firm commitment to quality, Samsung Bioepis aims to become the world’s leading biopharmaceutical company. Samsung Bioepis continues to advance a broad pipeline of biosimilar candidates that cover a spectrum of therapeutic areas, including immunology, oncology, ophthalmology and hematology. Samsung Bioepis is a joint venture between Samsung BioLogics and Biogen. For more information, please visit: www.samsungbioepis.com and follow us on social media – Twitter, LinkedIn.

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