This information is intended for use by health professionals

 This medicinal product is subject to additional monitoring. This will allow quick identification of new safety information. Healthcare professionals are asked to report any suspected adverse reactions. See section 4.8 for how to report adverse reactions.

1. Name of the medicinal product

Zynteglo 1.2-20 × 106 cells/mL dispersion for infusion.

2. Qualitative and quantitative composition

2.1 General description

A genetically modified autologous CD34+ cell enriched population that contains haematopoietic stem cells (HSC) transduced with lentiviral vector (LVV) encoding the βA-T87Q-globin gene.

2.2 Qualitative and quantitative composition

The finished product is composed of one or more infusion bags which contain a dispersion of 1.2-20 × 106 cells/mL suspended in cryopreservative solution. Each infusion bag contains approximately 20 mL of Zynteglo.

The quantitative information regarding strength, CD34+ cells, and dose for the medicinal product is provided in the Lot Information Sheet. The Lot Information Sheet is included inside the lid of the cryoshipper used to transport Zynteglo.

Excipient with known effect

Each dose contains 391-1564 mg sodium.

For the full list of excipients, see section 6.1.

3. Pharmaceutical form

Dispersion for infusion.

A clear to slightly cloudy, colourless to yellow or pink dispersion.

4. Clinical particulars
4.1 Therapeutic indications

Zynteglo is indicated for the treatment of patients 12 years and older with transfusion-dependent β-thalassaemia (TDT) who do not have a β00 genotype, for whom haematopoietic stem cell (HSC) transplantation is appropriate but a human leukocyte antigen (HLA)-matched related HSC donor is not available (see sections 4.4 and 5.1).

4.2 Posology and method of administration

Zynteglo must be administered in a qualified treatment centre by a physician(s) with experience in HSC transplantation and in the treatment of patients with TDT.

Patients are expected to enrol in a registry and will be followed long term in the registry in order to better understand the long-term safety and efficacy of Zynteglo.


The minimum recommended dose of Zynteglo is 5.0 × 106 CD34+ cells/kg. In clinical studies doses up to 20 × 106 CD34+ cells/kg have been administered. The minimum recommended dose is the same for adults and adolescents 12 years of age and older.

Zynteglo is intended for autologous use (see section 4.4) and should only be administered once.

Mobilisation and apheresis

Patients are required to undergo HSC mobilisation followed by apheresis to obtain CD34+ stem cells for medicinal product manufacturing (see section 5.1 for a description of the mobilisation regimen used in clinical studies).

The minimum target number of CD34+ cells to be collected is 12 × 106 CD34+ cells/kg. If the minimum dose of Zynteglo of 5.0 × 106 CD34+ cells/kg is not met after initial medicinal product manufacturing, the patient may undergo one or more additional cycles of mobilisation and apheresis, separated by at least 14 days, in order to obtain more cells for additional manufacture.

A back-up collection of CD34+ stem cells of at least 1.5 × 106 CD34+ cells/kg (if collected by apheresis) or >1.0 × 108 TNC/kg (if collected by bone marrow harvest) is required. These cells must be collected from the patient and be cryopreserved prior to myeloablative conditioning and infusion with Zynteglo. The back-up collection may be needed for rescue treatment if there is: 1) compromise of Zynteglo after initiation of myeloablative conditioning and before Zynteglo infusion, 2) primary engraftment failure, or 3) loss of engraftment after infusion with Zynteglo (see section 4.4).

Pre-treatment conditioning

The treating physician should confirm that HSC transplantation is appropriate for the patient before myeloablative conditioning is initiated (see section 4.4).

Full myeloablative conditioning must be administered before infusion of Zynteglo (see section 5.1 for a description of the myeloablative regimen used in clinical studies). It is recommended that patients maintain haemoglobin (Hb) ≥11 g/dL for 30 days prior to myeloablative conditioning. Iron chelation should be stopped at least 7 days prior to myeloablative conditioning. Prophylaxis for hepatic veno-occlusive disease (VOD) is recommended. Depending on the myeloablative conditioning agent administered, prophylaxis for seizures should be considered (see section 5.1 for a description of the prophylaxis regimen used in clinical studies.)

Myeloablative conditioning should not begin until the complete set of infusion bag(s) constituting the dose of Zynteglo has been received and stored at the administration site, and the availability of the back-up collection is confirmed.

Zynteglo administration

See Method of Administration below and section 6.6 for details on Zynteglo administration and handling.

After Zynteglo administration

Any blood products required within the first 3 months after Zynteglo infusion should be irradiated.

Restarting iron chelation after Zynteglo infusion may be necessary and should be based on clinical practice (see sections 4.5 and 5.1). Phlebotomy can be used in lieu of iron chelation, when appropriate.

Special populations


Zynteglo has not been studied in patients >65 years of age. HSC transplantation must be appropriate for a patient with TDT to be treated with Zynteglo (see section 4.4). No dose adjustment is required.

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. No dose adjustment is required.

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 (see section 4.4.). No dose adjustment is required.

Paediatric population

The safety and efficacy of Zynteglo in children <12 years of age have not yet been established.

Patients seropositive for human immunodeficiency virus (HIV) or human T-lymphotropic virus (HTLV)

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.

Method of administration

Zynteglo is for intravenous use only (see section 6.6 for full details on the administration process).

After completion of the 4-day course of myeloablative conditioning, there must be a minimum of 48 hours of washout before Zynteglo infusion.

Before infusion, it must be confirmed that the patient's identity matches the unique patient information on the Zynteglo infusion bag(s). The total number of infusion bags to be administered should also be confirmed with the Lot Information Sheet (see section 4.4).

Zynteglo infusion should be completed as soon as possible and no more than 4 hours after thawing. Each infusion bag should be administered in less than 30 minutes. In the event that more than one infusion bag is provided, all infusion bags must be administered. The entire volume of each infusion bag should be infused.

Standard procedures for patient management after HSC transplantation should be followed after Zynteglo infusion.

4.3 Contraindications

Hypersensitivity to the active substance or to any of the excipients listed in section 6.1.

Pregnancy and breast-feeding (see section 4.6).

Previous treatment with HSC gene therapy.

Contraindications to the mobilisation agents and the myeloablative conditioning agent must be considered.

4.4 Special warnings and precautions for use


The traceability requirements of cell-based advanced therapy medicinal products must apply.


Warnings and precautions of the mobilisation agents and the myeloablative conditioning agent must be considered.

Patients treated with Zynteglo should not donate blood, organs, tissues or cells for transplantation at any time in the future. This information is provided in the Patient Alert Card which should be given to the patient after treatment.

Risks associated with TDT and iron overload

Patients with TDT experience iron overload due to chronic red blood cell (RBC) transfusions that can lead to end organ damage. HSC transplantation with myeloablative conditioning is not appropriate for patients with TDT who have evidence of severely elevated iron in the heart i.e., patients with cardiac T2* <10 msec by magnetic resonance imaging (MRI). MRI of the liver should be performed on all patients prior to myeloablative conditioning. It is recommended that patients with MRI results demonstrating liver iron content ≥15 mg/g undergo liver biopsy for further evaluation. If the liver biopsy demonstrates bridging fibrosis, cirrhosis, or active hepatitis, HSC transplantation with myeloablative conditioning is not appropriate.

Risk of insertional oncogenesis

No cases of leukaemia or lymphoma have been reported in clinical studies with Zynteglo in patients with TDT. There are no reports of LVV-mediated insertional mutagenesis resulting in oncogenesis. Nevertheless, there is a theoretical risk of leukaemia or lymphoma after treatment with Zynteglo.

Patients should be monitored annually for leukaemia or lymphoma (including with a complete blood count) for 15 years post treatment with Zynteglo. If leukaemia or lymphoma is detected in any patient who received Zynteglo, blood samples should be collected for integration site analysis.

Serological testing

All patients should be tested for HIV-1/2 and HTLV-1/2 prior to mobilisation and apheresis to ensure acceptance of the apheresis material for Zynteglo manufacturing (see section 4.2).

Interference with serology testing

It is important to note that patients who have received Zynteglo are likely to test positive by polymerase chain reaction (PCR) assays for HIV due to LVV provirus insertion, 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.

Engraftment failure as measured by neutrophil engraftment

Treatment with Zynteglo involves the infusion and engraftment of CD34+ HSCs that have been genetically modified ex vivo with a LVV. In clinical trials, no patients failed to engraft bone marrow, as measured by neutrophil engraftment (N=42). Neutrophil engraftment occurred on median (min, max) Day 19.5 (13, 38) after medicinal product infusion. Failure of neutrophil engraftment is a short-term but potentially severe risk, defined as failure to achieve 3 consecutive absolute neutrophil counts (ANC) ≥500 cells/µL obtained on different days by Day 43 after infusion of Zynteglo. Patients who experience neutrophil engraftment failure should receive rescue treatment with the back-up collection (see section 4.2).

Delayed platelet engraftment

Platelet engraftment is defined as 3 consecutive platelet values ≥20 × 109/L obtained on different days after Zynteglo infusion, with no platelet transfusions administered for 7 days immediately preceding and during the evaluation period. Patients with TDT treated with Zynteglo who achieved platelet engraftment had a median (min, max) platelet engraftment on Day 41.0 (19, 191) in clinical trials (N=39). No correlation was observed between incidence of bleeding and delayed platelet engraftment. Patients should be made aware of the risk of bleeding until platelet recovery has been achieved. Patients should be monitored for thrombocytopenia and bleeding according to standard guidelines. Platelet counts should be monitored according to medical judgment until platelet engraftment and platelet recovery are achieved. Blood cell count determination and other appropriate testing should be promptly considered whenever clinical symptoms suggestive of bleeding arise.

Anti-retroviral and hydroxyurea use

Patients should not take anti-retroviral medications or hydroxyurea from at least one month prior to mobilisation until at least 7 days after Zynteglo infusion (see section 4.5). If a patient requires anti-retrovirals following exposure to HIV/HTLV, initiation of Zynteglo treatment should be delayed until an HIV western blot and viral load assay have been performed at 6 months post-exposure.

Sodium content

This medicinal product contains 391-1564 mg sodium per dose equivalent to 20 to 78% of the WHO recommended maximum daily intake of 2 g sodium for an adult.

4.5 Interaction with other medicinal products and other forms of interaction

Patients should not take anti-retroviral medicinal products or hydroxyurea from at least one month prior to mobilisation until at least 7 days after Zynteglo infusion (see section 4.4).

Drug-drug interactions between iron chelators and the myeloablative conditioning agent must be considered. Iron chelators should be discontinued 7 days prior to initiation of conditioning. The Summary of Product Characteristics (SmPC) for the iron chelator and the myeloablative conditioning agent must 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 (see sections 4.2 and 5.1).

No formal drug interaction studies have been performed. Zynteglo is not expected to interact with the hepatic cytochrome P-450 family of enzymes or drug transporters.

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

The safety of immunisation with live viral vaccines during or following Zynteglo treatment has not been studied.

4.6 Fertility, pregnancy and lactation

Women of childbearing potential/Contraception in males and females

There are insufficient exposure data to provide a precise recommendation on duration of contraception following treatment with Zynteglo. Women of childbearing potential and men capable of fathering a child must use a reliable method of contraception (intra-uterine device or combination of hormonal and barrier contraception) from start of mobilisation through at least 6 months after administration of Zynteglo. Consult the SmPC of the myeloablative conditioning agent for information on the need for effective contraception in patients who undergo conditioning.


A negative serum pregnancy test must be confirmed prior to the start of mobilisation and re-confirmed prior to conditioning procedures and before medicinal product administration.

No clinical data on exposed pregnancies are available.

Reproductive and developmental toxicity studies with Zynteglo were not performed. Zynteglo must not be used during pregnancy because of myeloablative conditioning (see section 4.3). It is unknown whether Zynteglo transduced cells have the potential to be transferred in utero to a foetus.

There is no opportunity for germline transmission of the βA-T87Q-globin gene after treatment with Zynteglo, therefore the likelihood that an offspring would have general somatic expression of the βA-T87Q-globin gene is considered negligible.


It is unknown whether Zynteglo is excreted in human milk. The effect of administration of Zynteglo to mothers on their breast-fed children has not been studied.

Zynteglo must not be administered to women who are breast-feeding.


There are no data on the effects of Zynteglo on human fertility. Effects on male and female fertility have not been evaluated in animal studies.

Data are available on the risk of infertility with myeloablative conditioning. It is therefore advised to cryopreserve semen or ova before treatment if possible.

4.7 Effects on ability to drive and use machines

Zynteglo has no influence on the ability to drive or use machines.

4.8 Undesirable effects

Summary of the safety profile

The safety of Zynteglo was evaluated in 42 patients with TDT. The most serious adverse reaction attributed to Zynteglo was thrombocytopenia (2.4%). Given the small patient population and size of cohorts, adverse reactions in the table below do not provide a complete perspective on the nature and frequency of these events.

Tabulated list of adverse reactions

Adverse reactions are listed by MedDRA body system organ class and by frequency. Frequencies are defined as: very common (≥1/10), and common (≥1/100 and <1/10).

Tables 1, 2, and 3 are lists of adverse reactions attributed to mobilisation/apheresis, myeloablative conditioning, and Zynteglo, respectively, experienced by patients with TDT in clinical trials with Zynteglo.

Table 1 Adverse reactions attributed to mobilisation/apheresis

System Organ Class (SOC)

Very Common (≥10%)

Common (≥1% - <10%)

Blood and lymphatic system disorders


Splenomegaly, Leukocytosis

Metabolism and nutrition disorders


Hypokalaemia, Hypomagnesaemia

Psychiatric disorders


Nervous system disorders

Headache, Peripheral sensory neuropathy

Dizziness, Head discomfort, Paraesthesia

Cardiac disorders

Cardiac flutter

Vascular disorders


Respiratory, thoracic and mediastinal disorders

Hypoxia, Epistaxis

Gastrointestinal disorders


Vomiting, Lip swelling, Abdominal pain, Abdominal pain upper, Paraesthesia oral

Skin and subcutaneous tissue disorders

Rash, Hyperhidrosis

Musculoskeletal and connective tissue disorders

Bone pain

Back pain, Musculoskeletal discomfort

General disorders and administration site conditions

Pyrexia, Influenza like illness, Chest discomfort, Chest pain, Injection site reaction, Catheter site haemorrhage, Catheter site bruise, Injection site bruising, Fatigue, Non-cardiac chest pain, Catheter site pain, Injection site pain, Puncture site pain, Pain


Blood magnesium decreased

Injury, poisoning and procedural complications

Citrate toxicity, Contusion, Procedural pain

Table 2 Adverse reactions attributed to myeloablative conditioning


Very Common (≥10%)

Common (≥1% - <10%)

Infections and infestations

Neutropenic sepsis, Systemic infection, Staphylococcal infection, Pneumonia, Lower respiratory tract infection, Urinary tract infection, Mucosal infection, Cellulitis, Vaginal infection, Rash pustular, Folliculitis, Gingivitis

Blood and lymphatic system disorders

Febrile neutropenia, Neutropenia, Thrombocytopenia, Leukopenia, Anaemia

Lymphopenia, Leukocytosis, Monocyte count decreased, Neutrophilia, Mean cell haemoglobin concentration increased

Metabolism and nutrition disorders

Decreased appetite

Hypocalcaemia, Hypokalaemia, Metabolic acidosis, Fluid overload, Fluid retention, Hypomagnesaemia, Hyponatraemia, Hypophosphataemia

Psychiatric disorders



Nervous system disorders


Dizziness, Lethargy, Dysgeusia

Eye disorders

Conjunctival haemorrhage

Ear and labyrinth disorders


Cardiac disorders

Atrial fibrillation

Vascular disorders

Hypotension, Haematoma

Respiratory, thoracic and mediastinal disorders

Epistaxis, Pharyngeal inflammation

Hypoxia, Dyspnoea, Pleural effusion, Rales, Upper-airway cough syndrome, Cough, Laryngeal pain, Hiccups

Gastrointestinal disorders

Stomatitis, Vomiting, Nausea, Diarrhoea, Gingival bleeding, Constipation, Abdominal pain, Anal inflammation,

Anal haemorrhage, Gastritis, Gastrointestinal inflammation, Abdominal distension, Abdominal pain upper, Anal fissure, Dyspepsia, Dysphagia, Oesophagitis, Haemorrhoids, Proctalgia. Lip dry

Hepatobiliary disorders

Veno-occlusive liver disease, Alanine aminotransferase increased, Aspartate aminotransferase increased, Blood bilirubin increased

Cholecystitis, Cholelithiasis, Hepatomegaly, Jaundice, Transaminases increased, Gamma-glutamyltransferase increased

Skin and subcutaneous tissue disorders

Alopecia, Pruritus, Skin hyperpigmentation

Petechiae, Ecchymosis, Pain of skin, Palpable purpura, Petechiae, Pruritus generalised, Purpura, Sweat gland disorder, Urticaria, Dry skin

Musculoskeletal and connective tissue disorders

Bone pain, Myalgia, Pain in extremity, Back pain

Renal and urinary disorders


Reproductive system and breast disorders

Vaginal haemorrhage

Ovarian failure, Menstruation irregular, Premature menopause, Blood follicle stimulating hormone increased, Blood testosterone decreased

General disorders and administration site conditions

Pyrexia, Fatigue

Mucosal inflammation, Face oedema, Hypothermia, Feeling cold, Pain, Xerosis


C-reactive protein increased, Aspergillus test positive, Blood potassium decreased, Weight decreased, Blood alkaline phosphatase decreased, Blood magnesium decreased, Forced expiratory flow decreased, Protein total decreased, Blood albumin decreased, Reticulocyte count decreased, Reticulocyte percentage decreased

Injury, poisoning and procedural complications

Transfusion reaction, Skin abrasion

Table 3 Adverse reactions attributed to Zynteglo


Very Common (≥10%)

Common (≥1% - <10%)

Blood and lymphatic system disorders


Vascular disorders

Hot flush

Respiratory, thoracic and mediastinal disorders


Gastrointestinal disorders

Abdominal pain

Musculoskeletal and connective tissue disorders

Pain in extremity

General disorders and administration site conditions

Non-cardiac chest pain

Description of selected adverse reactions


Bleeding is a potential complication of thrombocytopenia subsequent to myeloablative conditioning and treatment with Zynteglo. One serious event of hypotension due to epistaxis occurred in a patient, with onset 11 days after Zynteglo treatment. All other bleeding events were nonserious. A risk of bleeding exists before platelet engraftment and may continue after platelet engraftment in patients who have continued thrombocytopenia.

Following platelet engraftment, all patients maintained platelet levels of ≥20 × 109/L in the absence of platelet transfusions. Median (min, max) times to unsupported platelet counts of ≥50 × 109/L and ≥100 × 109/L were 52 (20, 268) days and 63 (20, 1231) days, respectively. (See section 4.4 for guidance on platelet monitoring and management.)

Hepatic veno-occlusive disease

Serious events of hepatic VOD occurred in 11.9% of patients following myeloablative conditioning; 80% of these patients did not receive prophylaxis for VOD. All patients who experienced VOD received treatment with defibrotide and recovered. Patients not receiving prophylaxis for VOD appeared to be at an increased risk for developing VOD. Patients with TDT may be at an increased risk of VOD following myeloablative conditioning compared with other patient populations.

Infusion related reactions to Zynteglo

Pre-medication for infusion reactions was managed at physician discretion. Infusion related reactions to Zynteglo were observed in 11.9% of patients and occurred on the day of Zynteglo infusion. All reactions resolved. Events were mild and included abdominal pain, hot flush, dyspnoea, and non-cardiac chest pain in 9.5%, 2.4%, 2.4%, and 2.4% of patients, respectively.

Paediatric population

According to available data, the frequency, type, and severity of adverse reactions in adolescents 12-17 years of age are similar to adults with the exception of VOD and pyrexia that occurred more frequently in adolescents.

Reporting of suspected adverse reactions

Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via:

Yellow Card Scheme

Website: or search for MHRA Yellow Card in the Google Play or Apple App Store

4.9 Overdose

No data from clinical studies are available regarding overdose of Zynteglo.

5. Pharmacological properties
5.1 Pharmacodynamic properties

Pharmacotherapeutic group: Other haematological agents, ATC code: not yet assigned

Mechanism of action

Zynteglo adds functional copies of a modified β-globin gene into the patients' HSCs through transduction of autologous CD34+ cells with BB305 LVV, thereby addressing the underlying genetic cause of the disease. 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 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 TDT and has the potential to increase total Hb to normal levels and eliminate dependence on chronic RBC transfusions. Following successful engraftment and achievement of transfusion independence, the effects of the product are expected to be life-long.

Pharmacodynamic effects

All patients with TDT with a non-β00 genotype who received Zynteglo with at least 3 months of follow-up produced HbAT87Q (N=10, HGB-204; N=4, HGB-205; N=14, HGB-207; N=1, HGB-212). For patients with at least 6 months of follow-up, HbAT87Q generally increased steadily after Zynteglo infusion and stabilised by approximately Month 6 to 9 post infusion. Patients had a Month 6 median (min, max) HbAT87Q of 4.90 (1.0, 9.6) g/dL in the Phase 1/2 studies (N=14, HGB-204 and HGB-205) and 9.49 (3.4, 10.6) g/dL in the ongoing Phase 3 study (N=11, HGB-207).

HbAT87Q remained generally stable through Month 24 with a median (min, max) of 6.44 (1.1, 10.1) g/dL (N=14, HGB-204 and HGB-205), and through long-term follow-up in LTF-303, demonstrating stable integration of the βA-T87Q-globin gene into long-term HSCs and stable expression of the βA-T87Q-globin gene in cells of the erythroid lineage.

Clinical efficacy

Efficacy was based on 32 adult and adolescent patients with TDT and a non-β00 genotype treated with Zynteglo (N=10, HGB-204; N=4, HGB-205; N=15, HGB-207; N=3, HGB-212) (see Table 4). Only a few patients have been included in the clinical studies with genotypes characterised by low endogenous β-globin production phenotypically similar to patients with a β00 genotype, such as patients homozygous for IVS-I-110 or IVS-I-5.

Table 4 Baseline characteristics for non-β00 patients with TDT ≥12 years of age treated with Zynteglo (Studies HGB-204, HGB-205, HGB-207, HGB-212, LTF-303)

Non-β00 patients


Total number



median (min, max)

Pre-treatment transfusion volumes


median (min, max)

Pre-treatment transfusions per year

median (min, max)





(16, 19)


(138.8, 197.3)


(10.5, 13.0)





(16, 34)


(140.0, 234.5)


(10.0, 16.5)





(12, 34)


(152.3, 251.3)


(11.5, 37.0)





(17, 33)


(170.7, 209.6)


(17.50, 39.5)

Transfusion-dependent β-thalassaemia (TDT)

Patients were considered to be transfusion-dependent if they had a history of transfusions of at least 100 mL/kg/year of RBCs or with ≥8 transfusions of RBCs per year in the 2 years preceding enrolment. In the clincal studies, patients received a median (min, max) RBC transfusion volume of 175.7 (139, 251) mL/kg/year and a median (min, max) number of 14.8 (10, 40) RBC transfusions per year.

Adolescents were excluded from Phase 3 studies if they had a known and available HLA-matched related HSC donor. The median (min, max) age in the studies was 19.0 (12, 34) years, 56.3% were females, 59.4% were Asian, and 40.6% White/Caucasian. All patients had a Karnofsky performance score ≥80 and the majority had a performance score of 100 at baseline. Cardiac T2* at baseline was >20 msec. The median (min, max) serum ferritin at baseline was 3778.7 (784, 22517) pmol/L and median (min, max) liver iron concentration was 6.75 (1.0, 41.0) mg/g (N=10, HGB-204; N=4, HGB-205; N=15, HGB-207; N=3, HGB-212).

Mobilisation and apheresis

All patients were administered G-CSF and plerixafor to mobilise 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 on Days 1 through 5 of mobilisation in the morning. The planned dose of plerixafor was 0.24 mg/kg/day, given on Days 4 and 5 of mobilisation in the evening. If a third day of collection was needed, plerixafor and G-CSF dosing was extended to Day 6. The dose of G-CSF should be decreased by half if white blood cell (WBC) count is >100 × 109/L prior to the day of apheresis. For most patients, the minimum number of CD34+ cells to manufacture Zynteglo was collected with 1 cycle of mobilisation 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 as a 3-hour IV infusion daily for 4 days with a recommended target AUC0-24h of 3800-4500 µM*min. The planned dose of busulfan was 0.8 mg/kg for patients 12-17 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 SmPC was used for information on appropriate method for determination of patient weight-based dosing. Busulfan dose adjustments were made as needed based on pharmacokinetic monitoring.

The median (min, max) busulfan dose was 3.50 (2.5, 5.0) mg/kg/day (N=32). AUC0-24h was measured on Day 1 and informed the dose for Day 3; the median (min, max) estimated daily AUC was 4417.0 (3030, 9087) μM*min (N=31). All patients with non-β00 genotypes received anti-seizure prophylaxis with agents other than phenytoin prior to initiating busulfan. Phenytoin was not used for anti-seizure prophylaxis because of its well understood induction of glutathione-S-transferase and cytochrome P450 and resultant increased clearance of busulfan, and because of the widespread availability of effective anti-seizure medications that do not affect busulfan metabolism.

In HGB-207 and HGB-212 prophylaxis for VOD/hepatic sinusoidal obstruction syndrome was required per institutional practice with ursodeoxycholic acid or defibrotide.

Zynteglo administration

All patients were administered Zynteglo with a median (min, max) dose of 7.80 × 106 (5.0, 19.4) CD34+ cells/kg as an intravenous infusion (N=32).

After Zynteglo administration

A total of 28.6% of patients (12/42; HGB-204, HGB-205, HGB-207, HGB-212) received G-CSF within 21 days after Zynteglo infusion. However, G-CSF use was not recommended for 21 days after Zynteglo infusion in Phase 3 studies.

Studies HGB-204 and HGB-205

HGB-204 and HGB-205 were Phase 1/2 open-label, single-arm 24-month studies that included 22 patients with TDT treated with Zynteglo (N=18, HGB-204; N=4, HGB-205), of whom 14 had a non-β00 genotype (N=10, HGB-204; N=4, HGB-205) and 8 had a β00 genotype in HGB-204. All patients completed HGB-204 and HGB-205 and enrolled for long-term follow-up in the LTF-303 study. The median (min, max) duration of follow-up was 40.48 (29.3, 58.6) months. All patients remain alive at last follow-up.

The primary endpoint was transfusion independence (TI) by Month 24, defined as a weighted average Hb ≥9 g/dL without any RBC transfusions for a continuous period of ≥12 months at any time during the study after infusion of Zynteglo. Of the patients with a non-β00 genotype, 11/14 (78.6%, 95% CI 49.2%-95.3%) achieved TI by Month 24 (Table 5). Among these 11 patients, the median (min, max) weighted average Hb during TI was 10.51 (9.3, 13.2) g/dL (Table 5).

All patients who have achieved TI at any time have maintained TI at Month 30 with a min, max duration of TI of 21.2+, 56.3+ months (N=11). The median (min, max) time to last RBC transfusion was 0.46 (0.2, 5.8) months following Zynteglo infusion.

In the 3 patients who did not achieve TI, reductions of 100%, 86.9% and 26.8% in transfusion volume requirements and of 100%, 85.3% and 20.7% in transfusion frequency were observed between Month 6 through Month 24 visit when compared to their pre-study levels of RBC transfusions.

The median (min, max) total Hb at Month 6 for patients who had not received a transfusion for the prior 60 days was 10.60 (7.6, 13.4) g/dL (N=11). Total Hb remained stable at Month 24 with a median (min, max) of 10.60 (8.8, 13.7) g/dL (N=12) and at Month 36 with a median (min, max) of 11.30 (7.8, 13.5) g/dL (N=11).

After Zynteglo infusion, patient iron levels were managed at physician discretion. All patients in HGB-204 restarted iron chelation and continue to use iron chelators. One patient in HGB-205 restarted iron chelation and continues to use iron chelators. Three patients in HGB-205 started phlebotomy.

At 48 months after infusion of Zynteglo for patients who achieved TI, the median reduction (min, max) in serum ferritin levels from baseline was 75.02% (39.2, 84.8) (N=3, HGB-204; N=2, HGB-205). The median reduction in liver iron content from baseline was 67.14%, ranging from an 83.3% reduction to a 269.2% increase (N=3, HGB-204; N=2, HGB-205).

Studies HGB-207 and HGB-212

HGB-207 and HGB-212 are ongoing Phase 3 open-label, single-arm 24-month studies that are planned to include approximately 39 adults, adolescents, and children with TDT (N=23, HGB-207; N=16, HGB-212), of whom 29 have a non-β00 genotype (N=23, HGB-207; N=6, HGB-212) and 10 have a β00 genotype in HGB-212. These studies are conducted with improved transduction compared to Phase 1/2 studies, resulting in increased average number of functional copies of the transgene (βA-T87Q-globin) integrated in the autologous CD34+ cells. Eighteen adults and adolescents with TDT with a non-β00 genotype have been treated with Zynteglo in Phase 3 studies (N=15, HGB-207; N=3, HGB-212) and their median (min, max) duration of follow-up was 10.0 (1.3, 22.2) months. All patients remain alive at last follow-up.

The primary endpoint was transfusion independence (TI) by Month 24, defined as a weighted average Hb ≥9 g/dL without any RBC transfusions for a continuous period of ≥12 months at any time during the study after infusion of Zynteglo. Five patients are evaluable for assessment of TI. Of these, 4/5 (80.0%, 95% CI 28.4-99.5%) achieved TI at last follow-up. Among these 4 patients, the median (min, max) weighted average Hb during TI was 12.42 (11.5, 12.6) g/dL (Table 5).

All patients who have achieved TI have maintained TI with a min, max duration of TI of 12.0+, 18.2+ months (N=4). The median (min, max) time to last RBC transfusion was 0.95 (0.5, 1.1) months following Zynteglo infusion.

For the only patient who did not achieve TI, a reduction of 75.8% in transfusion volume requirements and a reduction of 74.9% in transfusion frequency were observed between hospital discharge and through last study visit when compared to their pre-study levels of RBC transfusions.

The median (min, max) total Hb at Month 6 for patients who had not received a transfusion for the prior 60 days was 11.90 (8.4, 13.3) g/dL (N=11).

After Zynteglo infusion patient iron chelation was managed at physician discretion. Of the 11 patients followed for at least 6 months after Zynteglo infusion, 6 patients did not restart iron chelation or receive phlebotomy, 3 patients restarted iron chelation, and 2 patients received phlebotomy to reduce iron levels.

Exploratory analyses were performed to confirm resolution of dyserythropoiesis, the fundamental physiologic characteristic of TDT, in the bone marrow. Bone marrow biopsies taken before treatment were consistent with a diagnosis of TDT, including a low myeloid/erythroid ratio (N=15, HGB-207), reflective of erythroid hyperplasia. For 8 patients who had sufficient on-study follow-up to obtain a 12-month follow-up bone marrow assessment, myeloid/erythroid ratios for 7 patients increased from a range of 0.1 to 0.5 at baseline to a range of 0.6 to 1.9 approximately 12 months after Zynteglo infusion, suggesting that Zynteglo improves erythropoiesis in patients with TDT.

Overall results

Figure 1 Median total haemoglobin over time in non-β00 TDT patients treated with Zynteglo who have achieved transfusion independence (Studies HGB-204, HGB-205, HGB-207, LTF-303)

Bars represent interquartile ranges.

Table 5 Efficacy outcomes for non-β00 TDT patients treated with Zynteglo (Studies HGB-204, HGB-205, HGB-207, LTF-303)

HbAT87Q (g/dL) at 6 months



(min, max)

HbAT87Q (g/dL) at 24 months



(min, max)

Hb (g/dL) at 6 months*



(min, max)

Hb (g/dL) at 24 months*



(min, max)




[95% CI]

WA Hb during TI (g/dL)



(min, max)

Duration of TI




(min, max)

Study HGB-205



(4.94, 9.59)



(6.72, 10.13)



(7.6, 13.4)



(8.8, 13.6)



[19.4, 99.4]



(10.5, 13.0)



(34.9+, 56.3+)

Study HGB-204



(1.03, 8.52)



(1.10, 9.60)



(7.7, 13.3)



(9.1, 13.7)



[44.4, 97.5]



(9.3, 13.2)



(21.2+, 45.3+)

Study HGB-207



(3.35, 10.60)




(8.4, 13.3)




[28.4, 99.5]



(11.5, 12.6)



(12.0+, 18.2+)

*Patients who have not received transfusions in the prior 60 days.

**Transfusion independence (TI): a weighted average Hb ≥9 g/dL without any RBC transfusions for a continuous period of ≥12 months at any time during the study after medicinal product infusion.

***No patients are currently evaluable for these endpoints.

^N represents the total number of patients evaluable for TI, defined as patients who have completed their parent study (i.e., 24 months of follow-up), or achieved TI, or will not achieve TI in their parent study.

NR = Not reached. NA = Not applicable. Hb = Total Hb. WA Hb = Weighted average Hb.

Paediatric population

The European Medicines Agency has deferred the obligation to submit the results of studies with Zynteglo in one or more subsets of the paediatric population in β-thalassaemia (see section 4.2 for information on paediatric use).

This medicinal product has been authorised under a so-called 'conditional approval' scheme. This means that further evidence on this medicinal product is awaited. The European Medicines Agency will review new information on this medicinal product at least every year and this SmPC will be updated as necessary.

5.2 Pharmacokinetic properties

Zynteglo is an autologous gene therapy medicinal product consisting of autologous cells 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.

5.3 Preclinical safety data

Conventional mutagenicity, carcinogenicity and reproductive and developmental toxicity studies have not been conducted.

The pharmacology, toxicology and genotoxicity of the BB305 LVV used for transduction in the manufacture of Zynteglo were evaluated in vitro and in vivo. An in vitro immortalisation (IVIM) assay conducted with BB305 LVV-transduced mouse bone marrow cells (BMCs) showed minimal mutagenic potential (Fitness Score ≈ 0.1 × 10-4). Insertion site analysis (ISA) of pre-transplantation transduced mouse BMCs and human CD34+ HSCs showed no enrichment for insertion in or near cancer-related genes. A pharmacology, biodistribution, toxicity and genotoxicity study was conducted in a mouse model of β-thalassaemia. In this study, there was no evidence of toxicity, genotoxicity or oncogenesis (tumorigenicity) related to BB305 LVV integration, and no toxicity related to production of βA-T87Q-globin. ISA of post-transplantation BMCs demonstrated no preferred integration in the proximity of or within genes associated clinically (for gamma retroviral vectors) with either clonal dominance or leukaemia, and no evidence of clonal dominance was observed. Additional studies with human CD34+ HSCs administered to immunodeficient, myeloablated mice demonstrated no toxicity, tumorigenicity or genotoxicity.

6. Pharmaceutical particulars
6.1 List of excipients

Cryostor CS5

Sodium chloride

6.2 Incompatibilities

In the absence of compatibility studies, this medicinal product must not be mixed with other medicinal products.

6.3 Shelf life

Frozen: 1 year at ≤-140°C.

Once thawed: maximum 4 hours at room temperature (20°C-25°C).

6.4 Special precautions for storage

Store in the vapour phase of liquid nitrogen at ≤-140°C until ready for thaw and administration.

Keep the infusion bag(s) in the metal cassette(s).

Do not re-freeze after thawing.

6.5 Nature and contents of container

20 mL fluoro-ethylenepropylene infusion bag(s), each packed in a transparent pouch inside a metal cassette.

Zynteglo is shipped from the manufacturing facility to the infusion centre storage facility in a cryoshipper, which may contain multiple metal cassettes intended for a single patient. Each metal cassette contains one infusion bag with Zynteglo. A patient may have multiple infusion bags.

6.6 Special precautions for disposal and other handling

Irradiation could lead to inactivation of the product.

Precautions to be taken before handling or administering the medicinal product

• This medicinal product contains genetically modified human blood cells. Healthcare professionals handling Zynteglo should take appropriate precautions (wearing gloves, protective clothing and eye protection) to avoid potential transmission of infectious diseases.

Preparation for the infusion

• Remove each metal cassette from liquid nitrogen storage and remove each infusion bag from the metal cassette.

• Confirm that Zynteglo is printed on the infusion bag(s).

• Confirm that patient identity matches the unique patient identification information located on the Zynteglo infusion bag(s). Do not infuse Zynteglo if the information on the patient specific-label on the infusion bag does not match the intended patient.

• Account for all infusion bags and confirm each infusion bag is within the expiry date using the accompanying Lot Information Sheet.

• Each infusion bag should be inspected for any breaches of integrity before thawing and infusion. If an infusion bag is compromised, follow the local guidelines and contact bluebird bio immediately.

Thaw and administration

• Thaw Zynteglo at 37°C in a water bath or dry bath. Thawing of each infusion bag takes approximately 2 to 4 minutes. Do not overthaw the medicinal product. Do not leave the medicinal product unattended and do not submerge the infusion ports if thawed in a water bath.

• After thaw, mix the medicinal product gently by massaging the infusion bag until all of the contents are uniform. Expose the sterile port on the infusion bag by tearing off a protective wrap covering the port.

• Access the medicinal product infusion bag and infuse per the administration site's standard procedures for administration of cell therapy products. Do not use an in-line blood filter or an infusion pump.

• Do not sample, alter, or irradiate the medicinal product.

• 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 bag.

• Infuse Zynteglo as soon as possible and no more than 4 hours after thawing. Flush all Zynteglo remaining in the infusion bag and any associated tubing with at least 50 mL of 0.9% sodium chloride solution to ensure as many cells as possible are infused into the patient.

Precautions to be taken for the disposal of the medicinal product

The medicinal product contains genetically-modified cells. Local biosafety guidelines should be followed for unused medicinal products or waste material. All material that has been in contact with Zynteglo (solid and liquid waste) should be handled and disposed of as potentially infectious waste in accordance with local biosafety guidelines.

7. Marketing authorisation holder

bluebird bio (Netherlands) B.V.

Stadsplateau 7

WTC Utrecht

3521AZ Utrecht

The Netherlands

8. Marketing authorisation number(s)


9. Date of first authorisation/renewal of the authorisation

29 May 2019

10. Date of revision of the text

{DD month YYYY}

Detailed information on this medicinal product is available on the website of the European Medicines Agency