# Unexpected absence of fetal hemoglobin induction by lenalidomide in a patient with sickle cell anemia with concurrent multiple myeloma

## TL;DR

A patient with sickle cell anemia and multiple myeloma did not show fetal hemoglobin increase from lenalidomide, contradicting in vitro results.

## Contribution

Demonstrates lenalidomide does not induce fetal hemoglobin in a real-world clinical case, challenging prior in vitro findings.

## Key findings

- Lenalidomide treatment did not increase fetal hemoglobin levels in a patient with SCA and MM.
- Clinical outcomes did not align with previous in vitro studies suggesting lenalidomide induces fetal hemoglobin.
- The case highlights challenges in treating patients with overlapping hematologic conditions.

## Abstract

Sickle cell anemia (SCA) and multiple myeloma (MM) are debilitating hematologic diseases impacting hemoglobin and plasma cells, respectively. Despite differing origins, they share overlapping clinical features including bone pain and anemia. A cornerstone of SCA is to induce fetal hemoglobin through hydroxyurea treatment. Lenalidomide, a central treatment of MM, has also been shown to induce fetal hemoglobin in vitro. Here we present a case of a young woman with SCA and subsequently multiple myeloma. When lenalidomide was used as part of multiple myeloma treatment, we investigated the proposed induction of fetal hemoglobin, using high-pressure liquid chromatography. Over a treatment period of 114 days, we did not observe lenalidomide-induced increases in fetal hemoglobin and were thereby unable to replicate in vitro findings. Moreover, the case highlights many difficulties of diagnosing and treating patients with SCA and concurrent malignancies.

The online version contains supplementary material available at 10.1186/s13023-025-04052-0.