Seattle Genetics and Takeda Announce Four-Year Survival Data from ADCETRIS® (Brentuximab Vedotin) Pivotal Trial in Relapsed or Refractory Systemic Anaplastic Large Cell Lymphoma at ASH Annual Meeting

SAN FRANCISCO

Seattle Genetics, Inc. (Nasdaq: SGEN) and Takeda Pharmaceutical Company Limited (TSE:4502) today announced four-year overall survival (OS) data from the ADCETRIS (brentuximab vedotin) pivotal Phase 2 clinical trial in relapsed or refractory systemic anaplastic large cell lymphoma (ALCL). ADCETRIS is an antibody-drug conjugate (ADC) directed to CD30, which is expressed in classical Hodgkin lymphoma (HL) and systemic ALCL, a type of T-cell lymphoma. At a median follow up of 46.3 months, the estimated four-year survival rate was 64 percent. The data were presented at the 56^th American Society of Hematology (ASH) Annual Meeting and Exposition taking place in San Francisco, CA, December 6-9, 2014.

“Historical outcomes for patients with relapsed T-cell lymphoma, including systemic ALCL have been poor, with a median overall survival of 5.5 months and a median progression-free survival of 3.1 months. The four-year survival data from the pivotal trial in systemic ALCL demonstrate ADCETRIS’ activity in the treatment of this disease, with an estimated four-year survival rate of 64 percent and a median progression-free survival of 20 months,” said Clay B. Siegall, Ph.D., President and Chief Executive Officer of Seattle Genetics. “These encouraging data show durable, long-term responses in the relapsed systemic ALCL treatment setting and support the evaluation of ADCETRIS in earlier lines of therapy, including in the ongoing Phase 3 ECHELON-2 clinical trial in frontline mature T-cell lymphoma.”

“The data estimate that more than 60 percent of the relapsed or refractory ALCL patients treated with ADCETRIS in this study are alive at four years, which may positively redefine outcome expectations in this difficult to treat cancer,” said Dirk Huebner, M.D., Senior Medical Director, Oncology Therapeutic Area Unit, Takeda Pharmaceutical Company. “The fact that a third of all patients treated in the trial remain in complete remission with no evidence of disease after a median follow up of 46 months suggests the difference ADCETRIS can make in this disease.”

Four-Year Survival Data from an Ongoing Pivotal Phase 2 Study of Brentuximab Vedotin in Patients with Relapsed or Refractory Systemic Anaplastic Large Cell Lymphoma (Abstract #3095, poster presentation at 6:00 p.m. PT on Sunday, December 7, 2014 at the Moscone Center West Building, Level 1)

A pivotal, single-arm clinical trial was conducted in 58 relapsed or refractory systemic ALCL patients to assess the efficacy and safety of single-agent ADCETRIS. In addition, the trial was designed to determine duration of response, progression-free survival (PFS) and overall survival (OS). Patients received 1.8 milligrams per kilogram (mg/kg) of ADCETRIS administered through a 30-minute intravenous infusion every three weeks for up to 16 cycles. As previously reported, 86 percent of patients on the trial achieved an objective response, including 59 percent with a complete response (CR) and 28 percent with a partial response (PR).

Data from long-term patient follow up in this pivotal trial will be highlighted by Barbara Pro, M.D., Thomas Jefferson University, and include:

• After a median observation time of 46.3 months from the first dose of ADCETRIS, the median OS was 55.1 months and the estimated four-year OS was 64 percent.
• The median PFS per investigator was 20.0 months.
• Nineteen of 38 patients (50 percent) who achieved a CR on study per investigator assessment remained in remission at the time of last follow-up; for all patients who achieved a CR, median OS and PFS had not yet been reached.
• For the 16 CR patients who received a consolidative transplant (either allogeneic or autologous stem cell transplant), neither median PFS nor OS had been reached.
• For the 22 CR patients who did not receive a consolidative transplant, median PFS was 39.4 months and median OS had not yet been reached. Eight CR patients remained in remission without receipt of any subsequent anti-lymphoma therapy following ADCETRIS.
• The most common adverse events of any grade were peripheral neuropathy (57 percent), nausea (40 percent), fatigue (38 percent), pyrexia (34 percent) and diarrhea (29 percent).
• The most common Grade 3 or 4 adverse events occurring in at least five percent of patients were neutropenia (21 percent), peripheral neuropathy (17 percent), thrombocytopenia (14 percent), anemia (seven percent) and recurrent ALCL (five percent).

About ADCETRIS:

ADCETRIS (brentuximab vedotin) is an ADC comprising an anti-CD30 monoclonal antibody attached by a protease-cleavable linker to a microtubule disrupting agent, monomethyl auristatin E (MMAE), utilizing Seattle Genetics’ proprietary technology. The ADC employs a linker system that is designed to be stable in the bloodstream and release MMAE upon internalization into CD30-expressing tumor cells.

ADCETRIS for intravenous injection received accelerated approval from the U.S. Food and Drug Administration and approval with conditions from Health Canada for two indications: (1) the treatment of patients with HL after failure of ASCT or after failure of at least two prior multi-agent chemotherapy regimens in patients who are not ASCT candidates, and (2) the treatment of patients with sALCL after failure of at least one prior multi-agent chemotherapy regimen. The indications for ADCETRIS are based on response rate. There are no data available demonstrating improvement in patient-reported outcomes or survival with ADCETRIS.

ADCETRIS was granted conditional marketing authorization by the European Commission in October 2012 for two indications: (1) for the treatment of adult patients with relapsed or refractory CD30-positive HL following ASCT, or following at least two prior therapies when ASCT or multi-agent chemotherapy is not a treatment option, and (2) the treatment of adult patients with relapsed or refractory sALCL. ADCETRIS has received marketing authorization by regulatory authorities in 45 countries. See important safety information below.

Seattle Genetics and Takeda are jointly developing ADCETRIS. Under the terms of the collaboration agreement, Seattle Genetics has U.S. and Canadian commercialization rights and Takeda has rights to commercialize ADCETRIS in the rest of the world. Seattle Genetics and Takeda are funding joint development costs for ADCETRIS on a 50:50 basis, except in Japan where Takeda will be solely responsible for development costs.

About Seattle Genetics:

Seattle Genetics is a biotechnology company focused on the development and commercialization of innovative antibody-based therapies for the treatment of cancer. Seattle Genetics is leading the field in developing antibody-drug conjugates (ADCs), a technology designed to harness the targeting ability of antibodies to deliver cell-killing agents directly to cancer cells. The company’s lead product, ADCETRIS^® (brentuximab vedotin) is an ADC that, in collaboration with Takeda Pharmaceutical Company Limited, is commercially available for two indications in more than 45 countries, including the U.S., Canada, Japan and members of the European Union. Additionally, ADCETRIS is being evaluated broadly in more than 30 ongoing clinical trials. Seattle Genetics is also advancing a robust pipeline of clinical-stage ADC programs, including SGN-CD19A, SGN-CD33A, SGN-LIV1A, SGN-CD70A, ASG-22ME and ASG-15ME. Seattle Genetics has collaborations for its ADC technology with a number of leading biotechnology and pharmaceutical companies, including AbbVie, Agensys (an affiliate of Astellas), Bayer, Genentech, GlaxoSmithKline and Pfizer. More information can be found at www.seattlegenetics.com.

About Takeda Oncology:

The Takeda Oncology Business Unit, headquartered in Cambridge, MA, is co-located with the leadership of Takeda’s globally-integrated oncology research and development enterprise, overseen by the Oncology Therapeutic Area Unit. Takeda Oncology delivers novel medicines to patients with cancer worldwide through its commitment to science, breakthrough innovation and passion for improving the lives of patients. Takeda Oncology was formerly known as Millennium: The Takeda Oncology Company. Additional information about Takeda Oncology is available through its website, www.takedaoncology.com.

About Takeda Pharmaceutical Company Limited:

Located in Osaka, Japan, Takeda is a research-based global company with its main focus on pharmaceuticals. As the largest pharmaceutical company in Japan and one of the global leaders of the industry, Takeda is committed to strive towards better health for people worldwide through leading innovation in medicine. Additional information about Takeda is available through its corporate website, www.takeda.com.

ADCETRIS (brentuximab vedotin) U.S. Important Safety Information

BOXED WARNING

Progressive multifocal leukoencephalopathy (PML): JC virus infection resulting in PML and death can occur in patients receiving ADCETRIS.

Contraindication:

Concomitant use of ADCETRIS and bleomycin is contraindicated due to pulmonary toxicity.

Warnings and Precautions:

• Peripheral neuropathy: ADCETRIS treatment causes a peripheral neuropathy that is predominantly sensory. Cases of peripheral motor neuropathy have also been reported. ADCETRIS-induced peripheral neuropathy is cumulative. Monitor patients for symptoms of neuropathy, such as hypoesthesia, hyperesthesia, paresthesia, discomfort, a burning sensation, neuropathic pain or weakness and institute dose modifications accordingly.
• Infusion reactions: Infusion-related reactions, including anaphylaxis, have occurred with ADCETRIS. Monitor patients during infusion. If an infusion reaction occurs, interrupt the infusion and institute appropriate medical management. If anaphylaxis occurs, immediately and permanently discontinue the infusion and administer appropriate medical therapy.
• Hematologic toxicities: Grade 3 or 4 anemia, thrombocytopenia and prolonged (≥1 week) severe neutropenia can occur with ADCETRIS. Febrile neutropenia has been reported with ADCETRIS. Monitor complete blood counts prior to each dose of ADCETRIS and consider more frequent monitoring for patients with Grade 3 or 4 neutropenia. Closely monitor patients for fever. If Grade 3 or 4 neutropenia develops, manage by G-CSF support, dose delays, reductions or discontinuation.
• Serious infections and opportunistic infections: Infections such as pneumonia, bacteremia and sepsis/septic shock (including fatal outcomes) have been reported in patients treated with ADCETRIS. Closely monitor patients during treatment for the emergence of possible bacterial, fungal or viral infections.
• Tumor lysis syndrome: Closely monitor patients with rapidly proliferating tumor and high tumor burden.
• Progressive multifocal leukoencephalopathy (PML): JC virus infection resulting in PML and death has been reported in ADCETRIS-treated patients. In addition to ADCETRIS therapy, other possible contributory factors include prior therapies and underlying disease that may cause immunosuppression. Consider the diagnosis of PML in any patient presenting with new-onset signs and symptoms of central nervous system abnormalities. Evaluation of PML includes, but is not limited to, consultation with a neurologist, brain MRI, and lumbar puncture or brain biopsy. Hold ADCETRIS if PML is suspected and discontinue ADCETRIS if PML is confirmed.
• Stevens-Johnson syndrome (SJS): SJS has been reported with ADCETRIS. If SJS occurs, discontinue ADCETRIS and administer appropriate medical therapy.
• Embryo-fetal toxicity: Fetal harm can occur. Advise pregnant women of the potential hazard to the fetus.

Adverse Reactions:

ADCETRIS was studied as monotherapy in 160 patients in two Phase 2 trials. Across both trials, the most common adverse reactions (≥20%), regardless of causality, were neutropenia, peripheral sensory neuropathy, fatigue, nausea, anemia, upper respiratory tract infection, diarrhea, pyrexia, rash, thrombocytopenia, cough and vomiting.

Drug Interactions:

Concomitant use of strong CYP3A4 inhibitors or inducers, or P-gp inhibitors, has the potential to affect the exposure to MMAE.

Use in Specific Populations:

MMAE exposure is increased in patients with hepatic impairment and severe renal impairment. Closely monitor these patients for adverse reactions.

For additional important safety information, including Boxed WARNING, please see the full U.S. prescribing information for ADCETRIS at www.seattlegenetics.com or www.ADCETRIS.com.

ADCETRIS Global Important Safety Information

ADCETRIS^® is indicated for the treatment of adult patients with relapsed or refractory (r/r) CD30+ Hodgkin lymphoma (HL):

1. Following autologous stem cell transplant or
2. Following at least 2 prior therapies when autologous stem cell transplantation is not a treatment option

ADCETRIS is indicated for the treatment of adult patients with relapsed or refractory systemic anaplastic large cell lymphoma (sALCL).

ADCETRIS is contraindicated for patients who are hypersensitive to ADCETRIS. In addition, combined use of bleomycin and ADCETRIS causes pulmonary toxicity, and is contraindicated.

ADCETRIS can cause serious side effects, including:

• Progressive multifocal leukoencephalopathy (PML): John Cunningham virus (JCV) reactivation resulting in PML and death has been reported in patients treated with ADCETRIS. Patients should be closely monitored for new or worsening neurological, cognitive, or behavioral signs or symptoms, which may be suggestive of PML.
• Pancreatitis: Acute pancreatitis has been observed in patients treated with ADCETRIS. Fatal outcomes have been reported. Patients should be closely monitored for new or worsening abdominal pain.
• Pulmonary Toxicity: Cases of pulmonary toxicity have been reported in patients receiving ADCETRIS. In the event of new or worsening pulmonary symptoms (e.g., cough, dyspnoea), a prompt diagnostic evaluation should be performed.
• Serious infections and opportunistic infections: Serious infections such as pneumonia, staphylococcal bacteraemia, sepsis/septic shock (including fatal outcomes), and herpes zoster, and opportunistic infections such as Pneumocystis jiroveci pneumonia and oral candidiasis have been reported in patients treated with ADCETRIS. Patients should be carefully monitored during treatment for emergence of possible serious and opportunistic infections.
• Infusion-related reactions: Immediate and delayed infusion-related reactions, as well as anaphylaxis, have occurred with ADCETRIS. Patients should be carefully monitored during and after an infusion.
• Tumor lysis syndrome (TLS): TLS has been reported with ADCETRIS. Patients with rapidly proliferating tumor and high tumor burden are at risk of TLS and should be monitored closely and managed according to best medical practice.
• Peripheral neuropathy (PN): ADCETRIS treatment may cause PN that is predominantly sensory. Cases of peripheral motor neuropathy have also been reported. Patients should be monitored for symptoms of PN, such as hypoesthesia, hyperesthesia, paresthesia, discomfort, a burning sensation, neuropathic pain, or weakness.
• Hematological toxicities: Grade 3 or Grade 4 anemia, thrombocytopenia, and prolonged (equal to or greater than one week) Grade 3 or Grade 4 neutropenia can occur with ADCETRIS. Complete blood counts should be monitored prior to administration of each dose.
• Febrile neutropenia: Febrile neutropenia has been reported. Patients should be monitored closely for fever and managed according to best medical practice.
• Stevens-Johnson syndrome (SJS) and Toxic Epidermal Necrolysis (TEN): SJS and TEN have been reported. Fatal outcomes have been reported.
• Hyperglycemia: Hyperglycemia has been reported during trials in patients with an elevated body mass index (BMI) with or without a history of diabetes mellitus. Any patient who experiences an event of hyperglycemia should have their serum glucose closely monitored.
• Renal and hepatic impairment: There is limited experience in patients with renal and hepatic impairment. Population pharmacokinetic analysis indicated that MMAE clearance might be affected by moderate and severe renal impairment, and by low serum albumin concentrations. Elevations in alanine aminotransferase (ALT) and aspartate aminotransferase (AST) have been reported. Liver function should be routinely monitored in patients receiving brentuximab vedotin.
• Sodium content in excipients: This medicinal product contains a maximum of 2.1 mmol (or 47mg) of sodium per dose. To be taken into consideration for patients on a controlled sodium diet.

Serious adverse drug reactions were: neutropenia, thrombocytopenia, constipation, diarrhea, vomiting, pyrexia, peripheral motor neuropathy and peripheral sensory neuropathy, hyperglycemia, demyelinating polyneuropathy, tumor lysis syndrome, and Stevens-Johnson syndrome.

ADCETRIS was studied as monotherapy in 160 patients in two Phase 2 studies. Across both studies, adverse reactions defined as very common (≥1/10) were: infections, neutropenia, peripheral sensory neuropathy, diarrhea, nausea, vomiting, alopecia, pruritis, myalgia, fatigue, pyrexia, and infusion-related reactions. Adverse reactions defined as common (≥1/100 to <1/10) were: upper respiratory tract infection, herpes zoster, pneumonia, anemia, thrombocytopenia, hyperglycemia, peripheral motor neuropathy, dizziness, demyelinating polyneuropathy, cough, dyspnea, constipation, rash, arthralgia, back pain, and chills.

These are not all of the possible side effects with ADCETRIS. Please refer to Summary of Product Characteristics (SmPC) before prescribing.

For Seattle Genetics:

Certain of the statements made in this press release are forward looking, such as those, among others, relating to the estimated overall survival rates in ALCL resulting from treatment with ADCETRIS. Actual results or developments may differ materially from those projected or implied in these forward-looking statements. Factors that may cause such a difference include the potential that events occur more quickly than estimated thereby reducing the overall survival rate. In addition, historical results in clinical trials for ADCETRIS may not predict results in ongoing or future clinical trials of ADCETRIS and data resulting from additional trials with ADCETRIS may not support approvals in the studies indications. More information about the risks and uncertainties faced by Seattle Genetics is contained in the company’s 10-Q for the quarter ended September 30, 2014 filed with the Securities and Exchange Commission. Seattle Genetics disclaims any intention or obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise.