Benefit-risk of voxelotor, crizanlizumab, and l-glutamine in sickle cell disease: A systematic review.

In 30 seconds

This systematic review assessed clinical evidence for l-glutamine, crizanlizumab, and voxelotor in sickle cell disease, distinguishing core randomized evidence from supportive and follow-up reports. Eight studies contributed to the structured synthesis. L-glutamine reduced vaso-occlusive crisis burden in its pivotal trial (rate ratio, 0.75; 95% confidence interval, 0.62-0.90); crizanlizumab prolonged time to first crisis in SUSTAIN, while voxelotor primarily improved hemoglobin response. Sparse comparable evidence and overlapping reports precluded a primary pooled meta-analysis, so the authors concluded that findings support therapy-specific benefit signals rather than a class-level conclusion.

Key findings

• L-glutamine reduced vaso-occlusive crisis burden in the pivotal trial (rate ratio, 0.75; 95% confidence interval, 0.62-0.90).
• Crizanlizumab prolonged time to first vaso-occlusive crisis in SUSTAIN (hazard ratio, 0.50; 95% confidence interval, 0.33-0.75), with evidence dependent on one core randomized trial.
• Voxelotor primarily improved hemoglobin response (risk ratio, 7.84; 95% confidence interval, 3.52-17.4).
• No primary pooled meta-analysis was performed because comparable independent evidence was sparse and follow-up and reporting differed.

Why it matters

These therapies target different clinical domains, so their outcomes should not be treated as interchangeable measures of benefit. The review highlights the need to distinguish effects on vaso-occlusive morbidity from hemoglobin response and to consider replication, durability, and completeness of safety evidence when interpreting treatment-specific findings.

What to keep in mind

The evidence base was sparse, with limited comparable independent studies, differing follow-up, overlapping linked reports, and several noninformative safety outcomes; no primary pooled meta-analysis was possible.