A 70-year-old man with transfusion-dependent myelodysplastic syndrome (MDS) developed new hypoxemia 9 months into luspatercept treatment (2 months after a dose increase), prompting investigation into the cause and reversibility of his intrapulmonary vascular dilatation (IPVD).
Hypoxemia (resting SpO₂ 88%, requiring up to 90% FiO₂) was attributed to IPVD with a 7.5% shunt on MAA scintigraphy. After luspatercept was stopped, supplemental oxygen was discontinued by 7 weeks and repeat MAA scintigraphy at 10 weeks confirmed shunt resolution (3.6%).
Single case report limits causal certainty; underlying mild probable usual interstitial pneumonia may have contributed to hypoxemia; no rechallenge with luspatercept was performed to confirm causality.
Clinicians prescribing luspatercept should monitor for new or unexplained hypoxemia, as IPVD may be a reversible drug-related complication. If suspected, cessation of luspatercept appears to lead to resolution within weeks.
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