Adverse Reactions
Pentostatin is lymphotoxic. Aside from myelosuppression, pentostatin is immunosuppressive in particular by suppression of the CD4+ lymphocyte subset. CD4+ counts smaller than 200 per µl are usually seen during treatment with pentostatin and CD4+ count suppression can outlast the end of treatment by more than 6 months. With the exception of frequent herpes zoster infections the clinical consequences of the suppression of CD4+ counts in hairy cell leukaemia are not well understood yet. Long term consequences are not predictable, but currently there is no evidence for higher frequency of secondary malignancies.The following adverse events were reported during clinical studies in patients with hairy cell leukaemia who were refractory to alpha-interferon or were treated as front-line therapy. Most patients experienced an adverse event. The most commonly reported reactions were nausea and/or vomiting or leucopenia, each occurring in about 60% of patients. Fever, rash and fatigue were reported in about 40% of patients. Most adverse events were either mild or moderate diminished in frequency with continued therapy. Twelve percent of patients withdrew from treatment due to an adverse event. Many hairy cell leukaemia patients experience adverse events while under therapy with pentostatin. Given the natural history of the disease and the pharmacological properties of the drug it may be difficult in certain cases to discriminate between drug-related and disease-related adverse events. No extravasation injuries were reported in clinical studies.The following adverse reactions have been reported during clinical studies in patients with HCL or during post-authorization use of pentostatin, either as single agent or in combinations with various agents for unapproved indications. They have been listed as Very common (>10%), Common (1-10%), Uncommon (0.1-1%) or Rare (0.01-0.1%)Body SystemFrequencyAdverse ReactionInfections and InfestationsVery common(>10%)Upper respiratory infection, Rhinitis, Pharyngitis, Viral infectionCommon1(1-10%)Herpes Zoster, Infection (unspecified), Sinusitis, Cellulitis, Bacterial infection, Pneumonia, Conjunctivitis, Furunculosis, Herpes simplex, Bronchitis, Sepsis, Urinary tract infection, Abscess skin, Oral Candidiasis, Mycotic skin infection, Peri-anal abscess, E. Coli pneumonia, Fungal pneumonia, Septic shock, Staphylococcal infection, Urosepis, OsteomyelitisUncommon2(0.1-1%)Acute gastroenteritis, Pulmonary Aspergillosis, Clostridium Difficile colitis, Cystitis, Cytomegalovirus infectionRare2(0.01-0.1%)Oesophageal candidiasisNeoplasms benign, malignant and unspecified (incl cysts and polyps)Common1(1-10%)Neoplasms, Skin carcinomaUncommon2(0.1-1%)Tumor lysis syndromeBlood and Lymphatic System DisordersVery common(>10%)Leucopenia, thrombocytopenia, Anaemia, Blood disorder, Eosinophilia, Hypochromic anaemia, PancytopeniaCommon1(1-10%)Agranulocytosis, Acute leukaemia, Febrile neutropenia, Ecchymosis, Lymphadenopathy, SplenomegalyUncommon2(0.