2.1 Dose

ZYNTEGLO is provided as a single dose for infusion containing a suspension of CD34+ cells in one or more infusion bags. The minimum recommended dose of ZYNTEGLO is 5.0 × 106 CD34+ cells/kg.

See the Lot Information Sheet provided with the product shipment for additional information pertaining to dose.

2.2 Preparation Before ZYNTEGLO Infusion

Before mobilization, apheresis, and myeloablative conditioning are initiated, confirm that hematopoietic stem cell (HSC) transplantation is appropriate for the patient.

It is recommended that patients be maintained at a hemoglobin (Hb) ≥ 11 g/dL for at least 30 days prior to mobilization and 30 days prior to myeloablative conditioning.

Granulocyte-colony stimulating factor (G-CSF) and plerixafor were used for mobilization and busulfan was used for myeloablative conditioning. Refer to the prescribing information for the mobilization agent(s) and the myeloablative conditioning agent(s) prior to treatment.

Perform screening for hepatitis B virus (HBV), hepatitis C virus (HCV), human T-lymphotrophic virus 1 & 2 (HTLV-1/HTLV-2), and human immunodeficiency virus 1 & 2 (HIV-1/HIV-2) in accordance with clinical guidelines before collection of cells for manufacturing.

2.3 Administration

ZYNTEGLO is for autologous use only. The patient's identity must match the patient identifiers on the ZYNTEGLO cassette(s) and infusion bag(s). Do not infuse ZYNTEGLO if the information on the patient-specific label does not match the intended patient.

• Product must be administered within 4 hours after thawing.
• Do not use an in-line blood filter or an infusion pump.

1.

Before infusion, confirm that the patient's identity matches the unique patient identifiers on the ZYNTEGLO infusion bag(s). Use the Lot Information Sheet to confirm the total number of infusion bags to be administered.

2.

Expose the sterile port on the infusion bag by tearing off the protective wrap covering the port.

3.

Access the infusion bag and infuse ZYNTEGLO as soon as possible after thawing and complete the infusion within 4 hours.

4.

Administer each infusion bag of ZYNTEGLO via intravenous infusion over a period of less than 30 minutes. If more than one infusion bag is provided, administer each infusion bag completely before proceeding to thaw and infuse the next infusion bag.

5.

Flush all ZYNTEGLO remaining in the infusion bag(s) and any associated tubing with at least 50 mL of 0.9% sodium chloride solution to ensure that as many cells as possible are infused into the patient.

5.1 Delayed Platelet Engraftment

Delayed platelet engraftment has been observed with ZYNTEGLO treatment. Bleeding risk is increased prior to platelet engraftment and may continue after engraftment in patients with prolonged thrombocytopenia; 15% of patients had ≥ Grade 3 decreased platelets on or after Day 100.

Patients should be made aware of the risk of bleeding until platelet recovery has been achieved. Monitor patients for thrombocytopenia and bleeding according to standard guidelines. Conduct frequent platelet counts until platelet engraftment and platelet recovery are achieved. Perform blood cell count determination and other appropriate testing whenever clinical symptoms suggestive of bleeding arise.

5.2 Risk of Neutrophil Engraftment Failure

There is a potential risk of neutrophil engraftment failure after treatment with ZYNTEGLO. Neutrophil engraftment failure is defined as failure to achieve three consecutive absolute neutrophil counts (ANC) ≥ 500 cells/microliter obtained on different days by Day 43 after infusion of ZYNTEGLO. Monitor neutrophil counts until engraftment has been achieved. If neutrophil engraftment failure occurs in a patient treated with ZYNTEGLO, provide rescue treatment with the back-up collection of CD34+ cells.

5.3 Risk of Insertional Oncogenesis

There is a potential risk of lentiviral vector (LVV)-mediated insertional oncogenesis after treatment with ZYNTEGLO.

Patients treated with ZYNTEGLO may develop hematologic malignancies and should be monitored lifelong. Monitor for hematologic malignancies with a complete blood count (with differential) at Month 6 and Month 12 and then at least annually for at least 15 years after treatment with ZYNTEGLO, and integration site analysis at Months 6, 12, and as warranted.

In the event that a malignancy occurs, contact bluebird bio at 1-833-999-6378 for reporting and to obtain instructions on collection of samples for testing.

5.4 Hypersensitivity Reactions

Allergic reactions may occur with the infusion of ZYNTEGLO. The dimethyl sulfoxide (DMSO) in ZYNTEGLO may cause hypersensitivity reactions, including anaphylaxis.

5.5 Anti-retroviral and Hydroxyurea Use

Patients should not take prophylactic HIV anti-retroviral medications or hydroxyurea for at least one month prior to mobilization, or for the expected duration for elimination of the medications, and until all cycles of apheresis are completed [see Drug Interactions (7.2)].

If a patient requires anti-retrovirals for HIV prophylaxis, then confirm a negative test for HIV before beginning mobilization and apheresis of CD34+ cells.

5.6 Interference with Serology Testing

Patients who have received ZYNTEGLO are likely to test positive by polymerase chain reaction (PCR) assays for HIV due to integrated BB305 LVV proviral DNA, resulting in a false-positive test for HIV. Therefore, patients who have received ZYNTEGLO should not be screened for HIV infection using a PCR-based assay.

6.1 Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

The safety data described in this section reflect exposure to ZYNTEGLO in two open-label, single-arm clinical trials and one long-term follow-up study, in which 41 patients with β-thalassemia requiring regular transfusions were treated with ZYNTEGLO [see Clinical Studies (14)]. The median (min, max) age across the trials was 13 (4, 34) years; 49% were females; 49% were Asian, 44% White, 5% Other, 2% Not Reported. The median (min, max) duration of follow-up was 27.2 (4.1, 48.2) months.

In the two trials, serious adverse reactions occurred in 37% of patients as of last follow-up. The most common serious adverse reactions (> 3%) were pyrexia (fever), thrombocytopenia, liver veno-occlusive disease, febrile neutropenia, neutropenia, and stomatitis. There were no deaths.

The most common adverse reactions (≥ 20%) were mucositis, febrile neutropenia, vomiting, pyrexia (fever), alopecia (hair loss), epistaxis (nose bleed), abdominal pain, musculoskeletal pain, cough, headache, diarrhea, rash, constipation, nausea, decreased appetite, pigmentation disorder, and pruritus (itch).

Table 1 presents the non-laboratory treatment emergent adverse reactions reported in at least 10% of patients and Table 2 describes the laboratory abnormalities of Grade 3 or 4 that occurred in at least 10% of patients.

Other clinically important adverse reactions that occurred in less than 10% of patients include the following:

Cardiac disorders: congestive heart failure (2%)

Hepatobiliary disorders: Serious hepatic veno-occlusive disease (VOD) occurred in 3 (7%) patients; of these three, two had not received prophylaxis for VOD. All patients who experienced serious VOD received treatment with defibrotide and recovered. Patients with β-thalassemia requiring regular transfusions may be at an increased risk of VOD following myeloablative conditioning.1

Infections and infestations: pneumonia (7%)

Infusion-related reaction including abdominal pain (7%) and tachycardia (2%).

7.1 Live Vaccines

Follow institutional guidelines for vaccine administration. The safety of immunization with live viral vaccines during or following ZYNTEGLO treatment has not been studied.

7.2 Anti-retrovirals and Hydroxyurea

Patients should not take anti-retroviral medications or hydroxyurea for at least one month prior to mobilization or the expected duration for elimination of the medications, and until all cycles of apheresis are completed [see Warnings and Precautions (5.5)]. Anti-retroviral medications may interfere with manufacturing of the apheresed cells.

7.3 Iron Chelation

Drug-drug interactions between iron chelators and the myeloablative conditioning agent must be considered. Iron chelators should be discontinued at least 7 days prior to initiation of conditioning. The prescribing information for the iron chelator(s) and the myeloablative conditioning agent should be consulted for the recommendations regarding co-administration with CYP3A substrates.

Some iron chelators are myelosuppressive. After ZYNTEGLO infusion, avoid use of these iron chelators for 6 months. If iron chelation is needed, consider administration of non-myelosuppressive iron chelators. Phlebotomy can be used in lieu of iron chelation, when appropriate [see Clinical Studies (14)].

7.4 Erythropoiesis-Stimulating Agents

There is no clinical experience with the use of erythropoiesis-stimulating agents in patients treated with ZYNTEGLO.

8.1 Pregnancy

8.2 Lactation

8.3 Females and Males of Reproductive Potential

8.4 Pediatric Use

The safety and efficacy of ZYNTEGLO have been established in pediatric patients with β-thalassemia requiring regular transfusions. Use of ZYNTEGLO is supported by two Phase 3 studies [see Clinical Studies (14)] that included 27 pediatric patients in the following age groups: 16 children (less than 12 years) and 11 adolescents (age 12 years to less than 18 years).

No differences in efficacy or clinical safety were observed between the adult and pediatric subgroups. Engraftment times were longer in pediatric patients, but not associated with increases in infections or bleeding events. The median (min, max) time to neutrophil engraftment for patients less than 18 years was 26 (16, 39) days versus 21 (13, 27) days for patients 18 years or older. The median (min, max) time to platelet engraftment for patients less than 18 years was 50 (20, 94) days versus 43 (21, 58) days for patients 18 years or older. Longer engraftment time was associated with intact spleens.

The safety and efficacy of ZYNTEGLO in children less than 4 years of age have not been established. No data are available.

8.5 Geriatric Use

ZYNTEGLO has not been studied in patients > 65 years of age. Hematopoietic stem cell (HSC) transplantation must be appropriate for a patient to be treated with ZYNTEGLO.

8.6 Patients Seropositive for Human Immunodeficiency Virus (HIV)

ZYNTEGLO has not been studied in patients with HIV-1, HIV-2, HTLV-1, or HTLV-2. A negative serology test for HIV is necessary to ensure acceptance of apheresis material for ZYNTEGLO manufacturing. Apheresis material from patients with a positive test for HIV will not be accepted for ZYNTEGLO manufacturing.

8.7 Renal Impairment

ZYNTEGLO has not been studied in patients with renal impairment. Patients should be assessed for renal impairment, defined as creatinine clearance ≤ 70 mL/min/1.73 m2, to ensure HSC transplantation is appropriate.

8.8 Hepatic Impairment

ZYNTEGLO has not been studied in patients with hepatic impairment. Patients should be assessed for hepatic impairment to ensure HSC transplantation is appropriate.

12.1 Mechanism of Action

ZYNTEGLO adds functional copies of a modified β-globin gene into patients' hematopoietic stem cells (HSCs) through transduction of autologous CD34+ cells with BB305 LVV. After ZYNTEGLO infusion, transduced CD34+ HSCs engraft in the bone marrow and differentiate to produce RBCs containing biologically active βA-T87Q-globin (a modified β-globin protein) that will combine with α-globin to produce functional adult Hb containing βA-T87Q-globin (HbAT87Q). βA-T87Q-globin can be quantified relative to other globin species in peripheral blood using high-performance liquid chromatography. βA-T87Q-globin expression is designed to correct the β/α-globin imbalance in erythroid cells of patients with β-thalassemia and has the potential to increase functional adult HbA and total Hb to normal levels and eliminate dependence on regular pRBC transfusions.

12.2 Pharmacodynamics

HbAT87Q generally increased steadily after ZYNTEGLO infusion and stabilized by approximately Month 6 after infusion (Figure 1). Patients had a Month 6 median (min, max) HbAT87Q of 8.7 (0.0, 12.0) g/dL in the ongoing Phase 3 studies, Study 1 and Study 2 (N = 35).

HbAT87Q remained durable with a median (min, max) of 8.8 (0.3, 12.4) g/dL at Month 24 in the ongoing Phase 3 studies (N = 30). HbAT87Q in the Phase 3 studies continued to remain durable at last follow-up through Month 36, demonstrating sustained expression of the βA-T87Q protein derived from irreversible integration of the βA-T87Q-globin gene into long-term hematopoietic stem cells (HSCs).

12.3 Pharmacokinetics

ZYNTEGLO is an autologous gene therapy which includes hematopoietic stem cells (HSCs) that have been genetically modified ex vivo. The nature of ZYNTEGLO is such that conventional studies on pharmacokinetics, absorption, distribution, metabolism, and elimination are not applicable.

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

No carcinogenicity studies have been performed with ZYNTEGLO. Intravenous administration of ZYNTEGLO in a mouse model of β-thalassemia showed no evidence of toxicity, genotoxicity, or oncogenesis (tumorigenicity).

No studies have been conducted to evaluate the effects of ZYNTEGLO on fertility.

Mobilization and Apheresis

All patients were administered G-CSF and plerixafor to mobilize stem cells prior to the apheresis procedure. The planned dose of G-CSF was 10 µg/kg/day in patients with a spleen, and 5 µg/kg/day in patients without a spleen, given in the morning on Days 1 through 5 of mobilization. The planned dose of plerixafor was 0.24 mg/kg/day, given in the evening on Days 4 and 5 of mobilization. Apheresis generally occurred on mobilization Day 5 and 6 and if a third day of collection was needed, plerixafor and G-CSF dosing was extended to Day 6. The dose of G-CSF was decreased by half if the white blood cell (WBC) count exceeded 100 × 109/L prior to the day of apheresis. Most patients collected the minimum number of CD34+ cells to manufacture ZYNTEGLO with 1 cycle of mobilization and apheresis.

Pre-treatment Conditioning

All patients received full myeloablative conditioning with busulfan prior to treatment with ZYNTEGLO. The planned dose of busulfan was 3.2 mg/kg/day for patients 18 years and older as a 3-hour IV infusion daily for 4 consecutive days with a recommended target AUC0-24h of 3800-4500 µM*min. The planned dose of busulfan was 0.8 mg/kg for patients younger than 18 years of age as a 2-hour IV infusion every 6 hours for a total of 16 doses with a recommended target of AUC0-6h of 950-1125 µM*min.

The busulfan prescribing information was used for information on the appropriate method for determination of patient weight-based dosing. Busulfan dose adjustments were made as needed based on pharmacokinetic monitoring. In the clinical studies after completion of the 4-day course of busulfan, a washout period of at least 48 hours was required before ZYNTEGLO administration. Busulfan levels were measured 48 hours after final dose of busulfan for retrospective confirmation of adequate washout.

All patients received anti-seizure prophylaxis with agents other than phenytoin prior to initiating busulfan. Phenytoin was not used for anti-seizure prophylaxis because of its induction of cytochrome P450 and resultant increased clearance of busulfan.

Prophylaxis for hepatic veno-occlusive disease (VOD)/hepatic sinusoidal obstruction syndrome was required with ursodeoxycholic acid or defibrotide, per institutional guidelines.

ZYNTEGLO Administration

All patients (N = 41) were administered ZYNTEGLO with a median (min, max) dose of 9.4 (5.0, 42.1) × 106 CD34+ cells/kg as an intravenous infusion.

After ZYNTEGLO Administration

G-CSF was not recommended for 21 days after ZYNTEGLO infusion in Phase 3 studies. A total of 24% of patients (N = 10/41) received G-CSF within 21 days after ZYNTEGLO infusion.

Neutrophil engraftment was reported on median (min, max) Day 26 (13, 39) after ZYNTEGLO infusion.

As ZYNTEGLO is an autologous therapy, long-term immunosuppressive agents were not required in clinical studies.

Match the identity of the patient with the patient identifiers on the metal cassette(s), infusion bag(s), and Lot Information Sheet upon receipt.

• Keep the infusion bag(s) in the metal cassette(s) and store in the vapor phase of liquid nitrogen at less than or equal to -140°C (≤ -220°F) until ready for thaw and administration.
• Thaw ZYNTEGLO prior to infusion [see Dosage and Administration (2.2)].
• Do not re-freeze after thawing.
• Do not irradiate ZYNTEGLO, as this could lead to inactivation.