Course Faculty Response

• The patient should undergo testing for copy number alterations, specifically including assessment for trisomy 12, del(11q23), del(13q), and del(17p). Typically, this is performed by fluorescence in situ hybridization, but alternative platforms such as microarrays are also being used in some centers. If mantle cell lymphoma remains in the differential diagnosis following routine pathologic examination, FISH testing for CCND1 rearrangement could also be considered. This testing allows for risk stratification, with patients with isolated 13q deletion having a favorable prognosis, while patients with 17p or 11q deletions having an aggressive disease course. Patients with trisomy 12 or normal FISH findings have an intermediate prognosis.
   
• TP53 sequencing should also be performed. While most patients with TP53 mutations have a 17p deletion, not all patients with mutated TP53 harbor a deletion of the other allele. These patients would not be identified by FISH testing, and they have an aggressive disease course, similar to that seen in patients with 17p deletions. Direct Sanger sequencing and next generation sequencing (NGS) techniques are appropriate methodologies for this testing.
   
• IGHV hypermutation analysis should be performed. IGHV sequencing analysis divides patients with CLL into two distinct biologic subgroups. Those with evidence of somatic hypermutation at the IGHV locus (less than 98% homology to germline sequence) have mutated CLL, with a favorable prognosis. Patients with no evidence of somatic hypermutation (unmutated CLL, greater than 98% homology to germline) have an unfavorable prognosis. In addition to the hypermutation status, this analysis allows identification of the specific IGH gene used in the tumor, which may be clinically relevant (e.g., mutated CLL with IGHV3-21 usage is associated with more adverse outcomes than would be expected).
   
• Several phenotypic biomarkers are also associated with an adverse prognosis, including expression of ZAP70, CD38, and CD49d. While these are frequently assessed in clinical practice, their utility appears to be largely superceded by the genetic features mentioned above (copy number alterations, TP53 mutation, IGHV hypermutation status) and their presence or absence does not currently direct therapy, in contrast to the genetic biomarkers (see Dr. Parikh’s discussion).
   
• With the identification of several prognostic markers in the past two decades, it has become difficult for the practicing clinician to identify which factors are relevant.  Additionally, there are many patients in whom one prognostic factor appears to be favorable versus another to be unfavorable, which is also not very helpful.  Therefore, there have been efforts to combine these multiple prognostic markers into an integrated scoring system.
   
• The CLL-International Prognostic Index is the latest iteration of this effort. The CLL-IPI was developed by conducting multi-variate analysis of an extensive array of prognostic factors in 3472 patients participating in phase 3 trials across multiple institutions across the world.
   
• The analysis identified 5 independent predictors of overall survival (OS): age, clinical stage, del(17p) and/or TP53 mutation, IGHV mutation status, and serum β2-microglobulin level. Using a weighted grading system based on the hazard ratios for each factor in the multi-variate analysis, a prognostic index was derived that separated four risk categories (low, intermediate, high and very high) with 5-year OS ranging from 23% to 93%.
   
• The utility of this prognostic index was subsequently validated in an independent cohort of 838 newly diagnosed CLL patients seen at Mayo Clinic.
   
• In addition to OS, the CLL-IPI was also able to effectively stratify the time to first therapy (TFT), an important outcome measure for many patients who do not need therapy at the time of their initial CLL diagnosis.

Would conisder biopsy to rule out transformation as well as to check 17p/TP53 status if this is a recurrence 

If the patient is still fit, I would consider Bendamustine/Rituximab (if he does not have high risk cytogenetics). Ibrutinib will be another option. 

Course Faculty Response

In a prospective trial of 159 CLL patients, ~25% acquired new cytogenetic abnormalities by FISH testing on repeat testing (particularly among those patients who received CLL therapy). This suggests that all patients who are to begin therapy for relapsed disease should undergo retesting by CLL FISH to determine if they have acquired del17p, since this has important therapeutic implications.

Longitudinal data using whole-exome sequencing also shows that patients with CLL undergo clonal evolution, with the emergence of resistant subclones that may make the disease more difficult to treat.

Although several commercial panels are currently available to test recurrent mutations in CLL, the only mutation that is potentially actionable is the TP53 mutation. Other mutations such as NOTCH1, SF3B1, BIRC3, etc. are all shown to confer poor outcomes following therapy; however, there are no specific medications available to target these commonly mutated genes in CLL.

For patients who have either del17p or TP53 mutation, three FDA approved drugs are potential treatment options: ibrutinib (in both relapsed/refractory and frontline setting), idelalisib and rituximab (relapsed/refractory only), and venetoclax (relapsed/refractory only).

The choice of one of these agents depends on the comorbidities of the patients and the anticipated side-effects of the drugs. There are no head-to-head trials comparing the efficacy of these approaches.

The most common adverse events in patients who are treated with ibrutinib include diarrhea, atrial fibrillation, bleeding, myalgias and hypertension.

The most common adverse events in patients who are treated with idelalisib and rituximab include transaminitis, colitis and pneumonitis.

The most common adverse events in patients who are treated with venetoclax are tumor lysis syndrome and neutropenia.

This patient was found to have del17p on repeat FISH testing. Therapy with ibrutinib was started. Based on the most recent data, patients with relapsed/refractory CLL who have del17p, the median progression-free survival is ~26 months.

Course Faculty Summary

• Comprehensive morphologic and phenotypic characterization is necessary for the accurate diagnosis of CLL and its distinction from other entities in the differential diagnosis, particularly mantle cell leukemia.
• Once the diagnosis of CLL is established, additional genetic testing including assessment for del(13q), +12, del(11q), and del(17p), TP53 sequencing and IGHV hypermutation testing is necessary.
• Currently, comprehensive NGS testing to assess for mutations in  genes other than in TP53 is not necessary in routine clinical practice (e.g., NOTCH1, SF3B1, ATM, XPO1, BIRC3, EGR2, POT1, RPS15, etc.), as these alterations are not actionable; however, NGS techniques allow detection of small TP53-mutated clones, which may be clinically relevant.