Blood Podcast – March 27, 2025 Episode Summary

Main Theme

This episode presents insights from three recent articles published in Blood, focusing on:

• The use of itacitinib for preventing graft-versus-host disease (GVHD) and cytokine release syndrome in haploidentical hematopoietic cell transplantation (haplo-HCT)
• Clinical diagnosis and management of acute infection-associated purpura fulminans (PF)
• A systematic review examining evidence for sickle cell crisis–associated mortality in those with sickle cell trait

1. Itacitinib in Haploidentical Hematopoietic Cell Transplantation

(00:30–08:34)

Study Overview & Background

• Article: "Itacitinib for prevention of graft versus host disease and cytokine release syndrome in haploidentical transplantation" by Ramsey Abboud et al.
• Context: Haplo-HCT can be curative for hematological malignancies but is limited by high GVHD and CRS rates.
• Rationale: JAK-STAT pathway inhibition (by JAK inhibitors like itacitinib) has shown promise in matched transplants for GVHD reduction. The study investigates its efficacy/safety in a haploidentical setting.

Key Study Design Points

• 42 patients, single-arm, open-label, phase 2 trial.
• Idacitinib added to standard GVHD prophylaxis (posttransplant cyclophosphamide, tacrolimus, mycophenolate mofetil).
• Dosing: 200 mg/day, beginning 3 days pretransplant.
  • Pilot phase: 100 days posttransplant (20 pts)
  • Expansion phase: 180 days posttransplant (22 pts), with a subsequent 2-month taper.
• Major diagnoses: 60% acute myeloid leukemia, 21% ALL, 10% myelodysplastic syndrome.

Main Findings

• Engraftment: No primary graft failures, full donor chimerism at 30, 100, 180 days.

• Safety & Efficacy:

  • 0% grade 3–4 acute GVHD at days 100 and 180 (vs ~15% in historical controls)
  • Chronic GVHD: 5% at 1 year
  • No significant CRS above grade 1 (vs 30% grade 2 and ~20% grade 3–5 in prior studies)
  • Relapse: 10% at 1 year, 14% at 2 years
  • OS at 1 year: 80%; non-relapse mortality at 180 days: 8% (3 deaths from viral pneumonia, incl. 2 COVID-19)

• Immunological Insights:

  • Comparable immune reconstitution to controls.
  • Increased monocyte numbers and activation.
  • Fewer naïve T cells (potentially limiting severe GVHD).

Expert Commentary

“This study represents the first prospective trial of a JAK inhibitor as GVHD prophylaxis in haplo-HCT. Larger trials will be needed both to confirm itacitinib's activity in reducing severe GVHD and to show that it does not have negative consequences for graft viability, non-relapse mortality, and graft allo-reactivity against the malignancy being treated.”
— Nicholas von Bubnov, University Cancer Center Schleswig Holstein, Germany (08:01)

Memorable Moment

• No severe acute GVHD or severe CRS, suggesting significant potential for standard care alteration.

2. Diagnosis and Management of Purpura Fulminans

(08:34–19:45)

Case Introduction

• 39-year-old man presents with sore throat, malaise, rapidly spreading purpuric rash, and peripheral ischemia, soon developing shock. History includes dog bite.

Pathophysiology and Presentation

• PF is a life-threatening hematologic emergency, characterized by:
  • Rapid DIC,
  • Loss of endogenous anticoagulants (protein C, S, antithrombin)
  • Infectious trigger
  • Skin: red-bluish reticular lesions progressing to necrosis, affecting extremities/face first
  • Severe lactic acidosis out of proportion to shock severity

Treatment Protocols and Recommendations

• Aggressive Early Therapy:
  • Protein C concentrate (first-line)
  • Fresh frozen plasma if concentrate unavailable
  • Antithrombin repletion
  • IV Vitamin K
  • Unfractionated heparin for anticoagulation—risk/benefit favors use despite bleeding risks, except in high-bleeding-risk or frail patients.
  • Avoid low-molecular-weight heparins and direct thrombin inhibitors.
• Support: Transfusion (cryoprecipitate, platelets, RBCs, FFP), as necessary.
• Surgery: Avoid early amputation; conservative debridement preferred.

Recovery & Outcome

“[The patient] received protein C and antithrombin concentrates, intravenous unfractionated heparin, cryoprecipitate and fresh frozen plasma within six hours of initial presentation... After 58 days in an inpatient rehabilitation center, he was able to return to his work as a graphic designer.”
— Host narrating patient outcome (19:25)

Notable Clinical Advice

"PF is almost always treated empirically, ideally within the first few hours of presentation."
— Host (09:40)

"The risk of bleeding posed by [therapeutic anticoagulation with heparin] is outweighed by the clinical harm of rapid, uncontrolled coagulation."
— Host (15:55)

3. Sickle Cell Crisis–Associated Mortality & Sickle Cell Trait

(19:46–28:56)

Background & Review Purpose

• Article: "Sickle cell trait does not cause sickle cell crisis, leading to exertion-related death: a systematic review" by Lachelle Weeks et al.
• Sickle cell trait (SCT) is common (300 million worldwide); often cited as cause of exertion-related sudden death.

Study Approach

• Systematic review: 1,474 papers screened; 18 included (focus: pain crises, exertion-related death with SCT).
  • Exclusions: lack of original data, unclear diagnosis, outcomes not relevant.

Key Findings

• No Evidence of Acute Vaso-occlusive Crises in SCT:

  • None of 4 papers with possible cases had clear documentation.

• Mortality Data:

  • Only 1 of 14 papers on mortality analyzed exertion deaths by SCT status.
  • Retrospective study of ~48,000 Black soldiers found no increased risk of death (battle or non-battle) in those with SCT.
  • SCT associated with a 54% higher risk of heat-related rhabdomyolysis, but not with sudden death.

• Misconceptions:

  • Use of “sickled red cells” at autopsy is a misinterpretation—this can occur in SCT in postmortem hypoxia and does not indicate crisis.

Conclusions

“There is no evidence to support use of the terms vaso-occlusive pain episode, sickle cell crisis, exertional sickling with SCT or similar terms on death certificates for individuals with sickle cell trait.”
— Host summarizing the review’s findings (28:30)

Noteworthy Quotes

• On PF urgency:

  "PF is a life-threatening hematologic emergency... requires a high index of suspicion and rapid treatment." (09:41)

• On SCT and sudden death:

  "There is no published evidence for the occurrence of acute pain crises in individuals with sickle cell trait." (24:49)

Timestamps for Key Segments

• Itacitinib in haplo-HCT: 00:30–08:34
• Purpura fulminans diagnosis/management: 08:34–19:45
• Sickle cell trait/mortality review: 19:46–28:56

This summary covers research, commentary, and clinical recommendations from the Blood Podcast episode, providing clear insights and guidance on the discussed topics for those in hematology and related fields.