Sequencing Therapy for Elderly Chronic Lymphocytic Leukemia Patients in the Era of Novel Therapies: An Overview of Randomized Clinical Trials
Authors: Ahmad Malik Qistas , Sohail Chaudhry Saad , Yasir Muhammad , Tariq Muhammad Junaid , Akbar Arshia , Khalil Muhammad Jahanzeb , Usman Muhammad , Fraz Muhammad Asad , Jahngir Muhammad Umair , Khan Ali Younas , Ijaz Awais , Durer Ceren , Durer Seren , Anwer Faiz 
Published: October 2019

Abstract
Background:
For most of the elderly or unfit CLL patients, treatment algorithms focus on achievement of clinical response, relief of symptoms and prolongation of life expectancy. Comorbidities, frailty and reduced functional status in elderly patients make some of the standard treatments intolerable and less efficacious. However, recent advancements in understanding of CLL biology, approval of target agents including novel monoclonal antibodies and kinase inhibitors have expanded the horizons for treatment of CLL in elderly.
Methods:
We conducted a literature search on PubMed, Embase, Web of Science and ClinicalTrials.gov which was completed on July 1, 2018. To assess the CLL treatment protocols in the elderly population, we included data from phase II and phase III clinical trials from the last decade (Jan 2008 to Jan 2018).
Results:
From a total of 1259 studies, we selected 34 studies (n=3122) after inclusion criteria were met. The patients included are from the age group of ≥65 years with the mean age of 68.8 years. Male to female ratio was 3:2. On comparison of different parameters to look for the drug or regimen efficacy, we found that ibrutinib is very effective and tolerable in older (aged ≥65 years) treatment-naïve (TN) as well as relapsed refractory patients (RR), with overall response rate (ORR) of 91% for combined group in one study when compared to ofatumumab. When used in combination with ublituximab, the ORR peaked to 80% as compared to ibrutinib alone in patients with high risk cytogenetics (ORR=47%, p<0.001). Phase III RESONATE trial showed a comparison between ibrutinib and chlorambucil treated del 17p negative elderly patients; ibrutinib was superior in terms of ORR (86% vs. 35%) and overall survival (OS) (2-year OS, 98% vs. 85%, p=0.001). The OS with ibrutinib turned out to be 89% showing better disease control as compared to idelalisib (OS= 61%) when used in combination with rituximab, with a 33% reduction in mortality with ibrutinib as compared with idelalisib in RR patients. The combination of rituximab with idelalisib has shown promising results in patients with specific mutations (i.e. 100% ORR in those with del (17)/ Tp53 mutations, 97% ORR in those with unmutated IGHV). Similarly, when compared with placebo and rituximab combination progression free survival (PFS) was 13%, idelalisib is found to have PFS of 66% at 12 months in patients with del 17p/ Tp53 mutations and unmutated IGHV status. Moreover, in a phase II study, ofatumumab monotherapy showed ORR of 72%. In newly diagnosed (ND) CLL, an ORR of 98% is found with the pentostatin, cyclophosphamide, rituximab, and lenalidomide regimen. Other worth sharing results include; complete remission (CR) in 71% (24 out of 34 included) patients who were given lenalidomide as an initial therapy, with OS of 88% and ORR of 65%. The OS is surprisingly as high as 97.9% in those who were given pentostatin and cyclophosphamide in combination with ofatumumab. Traditional chemotherapy with fludarabine and rituximab (FR) showed OS of 67% in one study with rates of grades II and III-IV acute GVHD as 60% and 15% respectively. The most common hematological side effects seen with ibrutinib in one of the studies are neutropenia (12%), thrombocytopenia (4%) and anemia (7%). The non-hematological complications may be secondary due to cytopenias (infections, pneumonia, bleeding, and neutropenic fever) or due to constitutional symptoms like myalgia, fatigue, vomiting, or nausea.
Conclusion:
The rapid clinical development of novel therapy agents has changed the prognosis for CLL patients. Ibrutinib is considered as a standard option and an up front therapy for high risk CLL patients especially who are elderly and have del 17p, despite its significant toxicity profile in very elderly patients (80 years and above) where multiple deaths were reported. Future prospects include ibrutinib combinations with frontline chemo-immunotherapy (CIT) and other novel agents for TN and RR del 17p negative patients.

Disclosures
No relevant conflicts of interest to declare.