Recent developments in the use of pyruvate kinase activators as a new approach for treating sickle cell disease.

ABSTRACT: Pyruvate kinase (PK) is a key enzyme in glycolysis, the sole source of adenosine triphosphate, which is essential for all energy-dependent activities of red blood cells. Activating PK shows great potential for treating a broad range of hemolytic anemias beyond PK deficiency, because they also enhance activity of wild-type PK. Motivated by observations of sickle-cell complications in sickle-trait individuals with concomitant PK deficiency, activating endogenous PK offers a novel and promising approach for treating patients with sickle-cell disease.

Affirming Hormone Treatment for a Transgender Adolescent After a Venous Thromboembolic Event.

BACKGROUND: Medical affirmation, including gender-affirming hormones, is an essential component in the treatment of many transgender and gender-diverse youth. The risk of venous thromboembolism (VTE) during testosterone therapy for gender-affirming care is not fully elucidated. OBSERVATION: The case describes a 17-year-old transgender male treated with testosterone therapy who presented with an occlusive deep vein thrombosis of right axillary and subclavian veins. Testosterone level was 920 ng/dL at the time of the deep vein thrombosis, and he had no risk factors for VTE. A complete hypercoagulable workup was negative. CONCLUSIONS: The possibility of testosterone therapy as a risk factor for VTE may suggest the need to include this information during informed consent discussions. Long-term anticoagulation may be considered for those restarting testosterone therapy.

Hypoglycemia Due to Acquired Carnitine Deficiency in a Pediatric Patient Receiving Chemotherapy.

We describe a 21-month-old male with relapsed clear cell sarcoma of the kidney receiving enteral nutrition who experienced recurrent, ketotic hypoglycemia. During relapse therapy, he had recurrent hypoglycemia episodes, in the setting of hematochezia and diarrhea. Evaluation revealed low carnitine levels. He received supplementation with oral levocarnitine throughout the remainder of treatment, resulting in normalization of serum carnitine levels and no further hypoglycemia. We believe adverse effects of the chemotherapy on his single kidney and gastrointestinal insult resulted in hypoglycemia and carnitine deficiency. Our case highlights that carnitine deficiency should be considered when acute onset hypoglycemia without obvious cause occurs.

A Retrospective Review of Mercaptopurine Metabolism Reveals High Rate of Patients With Suboptimal Metabolites Successfully Corrected With Allopurinol.

Skewed drug metabolism of 6-mercaptopurine (6-MP) can jeopardize antileukemic effects and result in toxicities during the treatment of acute lymphoblastic leukemia and lymphoblastic lymphoma. Allopurinol can alter 6-MP metabolism to maximize therapeutic effects while reducing toxicities. Over 75% of our patients with acute lymphoblastic leukemia or lymphoblastic lymphoma experienced a 6-MP-related toxicity. Review of metabolite date a showed 6-methylmercaptopurine nucleotide levels were >10,000 in 55% of the cohort, suggesting 6-MP shunting. Allopurinol was initiated in 12 of 23 shunters with resolution of toxicities. We propose an algorithm to incorporate allopurinol into chemotherapy regimens for patients with inappropriate 6-MP metabolism.

Reduction of Factor VIII Inhibitor Titers During Immune Tolerance Induction With Recombinant Factor VIII-Fc Fusion Protein.

The development of inhibitors toward factor VIII (FVIII) is a common and serious complication of hemophilia A (HA) therapy. Patients with hemophilia who develop inhibitors often undergo time- and resource-intensive immune tolerance induction (ITI) protocols. We report a 15-month-old male with severe HA and a high-titer inhibitor that occurred while receiving prophylactic treatment with recombinant FVIII (rFVIII), in whom significant inhibitor titer reduction was achieved with thrice weekly infusions of a new, prolonged half-life rFVIII-Fc fusion protein product (trade name Eloctate). Further studies are warranted to explore the potential of Eloctate in ITI protocols.

Allopurinol Use During Maintenance Therapy for Acute Lymphoblastic Leukemia Avoids Mercaptopurine-related Hepatotoxicity.

6-Mercaptopurine (6-MP) is the mainstay of treatment for acute lymphoblastic leukemia and lymphoblastic lymphoma. It is metabolized into the pharmacologically active, 6-thioguanine nucleotide (6-TGN), and 6-methyl mercaptopurine nucleotides (6-MMPN), which is associated with hepatotoxicity that jeopardizes antileukemic therapy. Allopurinol alters the metabolism of 6-MP to increase 6-TGN levels and decreases 6-methyl mercaptopurine nucleotides levels. We report 2 cases in which combination therapy of allopurinol with 6-MP was used successfully to avoid hepatotoxicity while delivering adequate 6-TGN levels. We suggest that this combination therapy can be used safely to change the metabolite production in patients who develop excessive hepatotoxicity.