The European Commission (EC) has granted marketing authorisation to biotechnology company United Therapeutics Corporation's Unituxin (dinutuximab) for the treatment of high-risk neuroblastoma in patients aged 12 months to 17 years, who have previously received induction chemotherapy and achieved at least a partial response, followed by myeloablative therapy and autologous stem cell transplantation (ASCT).

Unituxin is administered in combination with granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-2 (IL-2), and isotretinoin.

Neuroblastoma is the most common extracranial solid cancer in childhood and the most common cancer in infancy, with an annual incidence in the European Union of approximately 1500 patients, of whom 50 per cent are diagnosed as having high-risk disease.

The European approval was based on demonstration of improved event-free survival (EFS) and overall survival (OS) in a multicenter, open-label, randomized trial (ANBL0032) sponsored by the US National Cancer Institute under a Cooperative Research and Development Agreement with United Therapeutics and conducted by the Children's Oncology Group (COG).

The trial randomized (1:1) 226 patients to either the Unituxin/13-cis-retinoic acid (RA) arm or the RA alone arm. Patients in each arm received six cycles of treatment. The Unituxin/RA arm consisted of Unituxin in combination with granulocyte macrophage-colony stimulating factor and RA (cycles 1, 3, and 5), Unituxin in combination with interleukin-2 and RA (cycles 2 and 4), and RA (cycle 6). Patients were 11 months to 15 years of age (median age 3.8 years).

The major efficacy outcome measure was investigator-assessed EFS, defined as the time from randomization to the first occurrence of relapse, progressive disease, secondary malignancy or death. The primary intent-to-treat analysis found an improvement in EFS associated with dinutuximab immunotherapy plus isotretinoin as compared to isotretinoin alone. The two-year estimates of EFS were 66 per cent among subjects receiving dinutuximab immunotherapy plus isotretinoin as compared with 48 per cent in subjects receiving isotretinoin alone (log-rank test p = 0.033) although this difference did not reach formal statistical significance according to the pre-specified plan for interim analyses. In addition, OS was evaluated with 3 years of follow-up after the EFS analysis as a secondary endpoint with a significant improvement observed among ITT subjects randomly allocated to receive dinutuximab immunotherapy plus isotretinoin as compared with isotretinoin alone. The three-year estimates of OS were 80 per cent compared with 67 per cent among subjects receiving dinutuximab immunotherapy plus isotretinoin and isotretinoin alone, respectively (log-rank test p = 0.0165).

Long-term overall survival was evaluated with five years of follow up after the EFS analysis and continued to demonstrate a survival advantage for patients who received dinutuximab immunotherapy compared to those who received isotretinoin alone. The five-year estimates of OS were 74 per cent for dinutuximab immunotherapy compared to 57 per cent for isotretinoin alone (log-rank test p = 0.030).

The most frequently occurring (more than 30 per cent of patients) adverse reactions reported during the neuroblastoma studies were hypotension (67 per cent), pain (66 per cent), hypersensitivity (56 per cent), pyrexia (53 per cent), urticaria (49 per cent), capillary leak syndrome (45 per cent), anaemia (45 per cent), hypokalaemia (41 per cent), platelet count decreased (40 per cent), hyponatraemia (37 per cent), alanine aminotransferase increased (35 per cent), decreased lymphocyte count (34 per cent) and decreased neutrophil count (31 per cent). Additional adverse reactions characteristic of an allergic response were also reported - including anaphylactic reaction (18 per cent) and bronchospasm (4 per cent).

Unituxin is to be administered by intravenous infusion over five courses at a daily dose of 17.5 mg/m2. It is administered on days 4-7 during courses 1, 3 and 5 (each course lasting approximately 24 days) and on days 8-11 during courses 2 and 4 (each course lasting approximately 28 days).

The treatment regimen consists of Unituxin, GM-CSF, IL-2, and isotretinoin, administered over six consecutive courses.

Unituxin is a monoclonal chimeric antibody composed of murine variable heavy and light chain regions and the human constant region for the heavy chain kappa. Unituxin reacts specifically with the ganglioside GD2, which is highly expressed on the surface of the neuroblastoma cells and minimally expressed on the surface of normal human neurons, peripheral pain fibres, and skin melanocytes.

On March 10, 2015, Unituxin, in combination with GM-CSF, IL-2 and RA, became the first therapy to be approved by the US Food and Drug Administration for the treatment of paediatric patients with high-risk neuroblastoma who achieve at least a partial response to prior first-line multiagent multimodality therapy.