Immunoglobulin holds promise for treatment-resistant polyneuropathy in diabetics

Treatment with intravenous immunoglobulin (IVIG) offers significant pain relief in patients with painful diabetic polyneuropathy (DPN) resistant to standard therapies, without deleterious side effects, according to the results of a trial.

Four weeks after treatment, the primary endpoint of 50-percent decrease in pain intensity occurred more frequently in the IVIG vs placebo arm (63.6 percent vs 0 percent; p=0.0013). Pain intensity decreased by a mean of 44.2 percent with active treatment, significantly greater than the 5.2-percent reduction obtained with placebo (p≤0.027). [Pain Med 2020;doi:10.1093/pm/pnz331]

Results for the secondary endpoints supported the primary efficacy data. IVIG produced better improvements in pain symptoms (Neurophatic Pain Symptom Inventory questionnaire), quality of life (SF-36 Health Survey questionnaire) and overall clinical judgment (assessed by the physician and the patient [Clinical/Patient Global Impression of Change questionnaire]) at all visits conducted.

Only two adverse events occurred throughout the study. One was a mild case of dermatitis psoriasiform in the treatment arm; the other was mild influenza in a placebo-treated patient.

The analysis included 23 diabetic patients with DPN randomly assigned to receive either IVIG (0.4 g/kg/d; n=11) or placebo (n=12) for 5 consecutive days. Baseline pain severity was >60 units on a visual analogue scale (VAS), and all patients were unresponsive to antidepressants and antiepileptic drugs.

Researchers asked the patients to complete the VAS scale daily and record the results in a diary during the window between visits 1–2 (7 days; week 1), visits 2–3 (5 days; week 2), visits 3–4 (1 month; weeks 3, 4, 5 and 6) and visits 4–5 (1 month; weeks 7, 8, 9 and 10).

The present data are in line with a previous study reporting significant pain relief with IVIG in patients with DPN resistant to standard therapies. “Even with a relatively small sample size, our results showed statistically significant improvement in favour of IVIG in both primary and secondary outcomes,” the researchers pointed out. [Pain Med 2012;13:1334-1341]

“We had no significant side effects in our patients, even at the dose of 2 g IVIG/kg. This was probably related to the administration of a 5-percent concentration of immunoglobulins over 5 days, in addition to [its] good safety profile … including in patients with neurologic diseases,” they added.

An immune-modulating blood-derived product, IVIG possesses putative anti-inflammatory mechanisms, such as blockade of the Fc receptor, enhancement of antibody catabolism, and the suppression of proinflammatory cytokines. [J Neurol 2008;255(Suppl 3):3-6]

“Further investigations are necessary to confirm our data. More patients need to be enrolled,” the researchers said. “We hope to involve more centres worldwide for a larger clinical trial.”