Cancer Treatment with Gemcitabine Does Not Increase Fetal Hemoglobin Levels.

Pharmacological induction of fetal hemoglobin (Hb F) can benefit patients with beta-hemoglobinopathies. Hydroxyurea (HU) is the drug most commonly used to induce Hb F. HU is converted to a free radical scavenger in vivo and inhibits the R2 subunit of ribonucleotide reductase. When used in the treatment of myeloproliferative syndromes, HU has been described to increase Hb F in people without hemoglobinopathies (Alter et al, Blood 66(2) 373-5). Gemcitabine is a nucleoside analog chemotherapeutic that inhibits the large R1 subunit of ribonucleotide reductase. We hypothesized that like HU, gemcitabine treatment would cause Hb F percentage to rise. Though oncology patients are a distinct population, gemcitabine induction of Hb F during the treatment of cancer would suggest a potential role for gemcitabine in the management of beta-hemoglobinopathies such as sickle cell disease and beta-thalassemia.

Participants for this prospective observational cohort study were recruited from the Moores UCSD Cancer Center upon documentation of a cancer diagnosis and oncologist-initiated plans for treatment with single agent gemcitabine. Enrolled subjects were gemcitabine naïve and had not received any chemotherapy for the preceding 4 weeks. Serum Hb F was quantified by electrophoresis prior to each of the first 4 gemcitabine treatments. All other laboratory evaluation was standard-of-care. The primary objective was to assess changes in Hb F among cancer patients in response to their initial 3 treatments with gemcitabine. Enrollment was halted early given the absence of a substantial treatment effect among the first 6 subjects.

Six subjects were eligible. Three were men. Five were Caucasian and one was an Asian/Pacific Islander. All subjects received gemcitabine monotherapy for the treatment of adenocarcinoma of the pancreas or breast at a weekly dose of 1000 mg/m2. Baseline Hb F range was 0 – 1.0%. Four of the six subjects (three women, one man; all Caucasian) experienced no change in Hb F from baseline to the final measurement. Two subjects experienced a 0.4% increase in Hb F from baseline to the final measurement 4 weeks later. Final Hb F range was 0 – 1.4%.

We found that gemcitabine monotherapy for the treatment of cancer did not induce Hb F in this small study cohort. Gemcitabine may lack this ability. Alternative explanations for the absence of clinically meaningful Hb F induction include the small population studied, differences between oncology patients and the general population, short duration of treatment, and intermittent dosing of gemcitabine.

No relevant conflicts of interest to declare.