A 68-year-old man is found to have an absolute lymphocyte count of 18,000/μL with smudge cells on peripheral smear. Flow cytometry shows CD5+, CD19+, CD23+, CD20 dim, FMC7-. Fluorescence in situ hybridisation (FISH) reveals del(17p). Per current CLL guidelines, this genetic finding influences treatment by:

• A Predicting excellent response to fludarabine-cyclophosphamide-rituximab (FCR)
• B Indicating trisomy 12 with excellent prognosis
• C Mandating immediate allogenic stem cell transplantation
• D Indicating p53 dysfunction with poor response to chemoimmunotherapy; BTK inhibitors (ibrutinib/acalabrutinib) or venetoclax preferred ✓

Explanation

Del(17p) in CLL results in loss of TP53 tumour suppressor function (p53 pathway). These patients respond poorly to alkylating agents and purine analogues (chemoimmunotherapy like FCR). Current guidelines (iwCLL/ESMO) recommend BTK inhibitors (ibrutinib, acalabrutinib, zanubrutinib) or venetoclax-based regimens as preferred frontline therapy for del(17p)/TP53-mutated CLL. This is one of the most important prognostic markers guiding treatment choice in CLL. Del(17p) predicts median survival of only 2–3 years without targeted therapy.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.