Lack of efficacy of pyridoxine (vitamin B6) treatment in acquired idiopathic sideroblastic anaemia, including refractory anaemia with ring sideroblasts

Pyridoxine, or vitamin B6, is commonly used to treat acquired idiopathic sideroblastic anaemia (AISA, including refractory anaemia with ring sideroblasts), but the efficacy of this therapy in an unselected AISA population (i.e. patients without confirmed ALAS2 or other pyridoxine-responsive germline mutations) has not been established. We reviewed clinical data from 231 patients with AISA and found that 42% of 203 evaluable patients had been treated with pyridoxine. Only 6.8% of pyridoxine-treated patients experienced a haemoglobin improvement (≥ 1.5 g/dL) meeting 2006 International Working Group for Myelodysplastic Syndromes standardised response criteria. As some patients received combination therapy with erythropoietin or other agents, improvement could be attributed to pyridoxine monotherapy in only one patient (1.4%). Smaller, less meaningful increments in haemoglobin levels of 0.5 g/dL were observed in 13.5% of patients. Response to therapy did not correlate with International Prognostic Scoring System (IPSS) risk group or multilineage vs unilineage dysplasia. New symptomatic peripheral neuropathy was noted in 2.3% of patients treated with pyridoxine. In this large series of unselected patients with sideroblastic anaemia, pyridoxine therapy was ineffective and was associated with a risk of adverse effects. Pyridoxine therapy should be reserved for patients with known or suspected pyridoxine-responsive mutations.