Can Vorinostat cause leukopenia and anemia?

Can Vorinostat Account for These Blood Count Changes?

Yes, vorinostat can directly cause both the leukopenia (low WBC 3.3) and anemia (elevated RBC 6.12 with low MCV 77.1 and low MCHC 30.1) observed in these labs, as hematologic toxicities are well-documented adverse effects of this HDAC inhibitor. 1, 2

Hematologic Toxicities of Vorinostat

Leukopenia and Neutropenia

• Leukopenia is a common adverse effect of vorinostat, occurring in 20-42% of patients across multiple clinical trials 3, 4
• In a phase I study of vorinostat in head and neck cancer with concurrent chemoradiation, leukopenia occurred in 20/26 patients (77%), with grade 3/4 leukopenia in 11 patients (42%) 3
• Your absolute neutrophil count (ANC) of 1680 is at the lower end of normal, consistent with mild drug-induced myelosuppression 3
• Lymphopenia was particularly common, with grade 3/4 lymphopenia occurring in 17/26 patients (65%) in one trial 3

Anemia

• Anemia is one of the most frequently reported hematologic toxicities with vorinostat, occurring in the majority of treated patients 3, 5
• In the head and neck cancer trial, anemia occurred in 23/26 patients (88%) 3
• Grade 3+ thrombocytopenia occurred in 12-16.7% of patients across studies 6, 5
• Your platelet count of 151 is at the lower end of normal, suggesting mild bone marrow suppression 6

Pattern Analysis of Your Labs

Microcytic Anemia Pattern

• Your elevated RBC count (6.12) with low MCV (77.1) and low MCHC (30.1) suggests microcytic anemia, which is not the typical pattern from vorinostat alone 2
• This pattern is more consistent with iron deficiency anemia or thalassemia trait, which may be pre-existing and unrelated to vorinostat 2
• Vorinostat typically causes normocytic anemia from bone marrow suppression, not microcytic anemia 6, 4

Leukopenia Pattern

• Your WBC of 3.3 with normal neutrophil percentage (50.3%) but low absolute lymphocyte count (0.99) is consistent with vorinostat-induced myelosuppression 3, 4
• The lymphopenia is particularly characteristic of HDAC inhibitor toxicity 3

Clinical Significance and Monitoring

Risk Factors Present

• The combination of leukopenia and anemia increases infection risk and may require dose modification 2
• Baseline complete blood counts should have been obtained before starting vorinostat 2
• Advanced age and concurrent medications increase the risk of medication-induced cytopenias 2

Management Recommendations

• Monitor CBC weekly during initial therapy, then every 2-4 weeks once stable 2, 6
• Consider dose reduction if ANC falls below 1000 or if grade 3/4 anemia develops 6, 4
• Evaluate for other causes of microcytic anemia (iron studies, ferritin) as this pattern suggests a concurrent process 2
• G-CSF support should be considered if neutropenia worsens or if febrile neutropenia develops 2

Common Pitfalls to Avoid

• Do not attribute all cytopenias to vorinostat without investigating other causes, particularly when the pattern (microcytic anemia) is atypical for the drug 2, 6
• Do not continue full-dose vorinostat if cytopenias worsen, as this increases infection and bleeding risk 6, 4
• The elevated eosinophil percentage (7.8%) and monocyte percentage (11.1%) may represent reactive changes and should be monitored 3