Ibrutinib Adapted to Response in Patients With CLL

Chronic lymphatic leukemia is the most common form of leukemia in adults, most often arising from a malignant clone of B cells with a characteristic phenotype. It is far from uniform in presentation and clinical course. About a third of patients never require treatment and have a long survival; in another third, an initial indolent phase is followed by disease progression; the remaining third of patients have aggressive disease at onset and require immediate treatment.

The development of the Rai and Binet staging systems has allowed the division of patients with chronic lymphocytic leukemia into three prognostic groups: good, intermediate and poor prognosis.

The two staging systems have improved the identification of patients who need immediate treatment.

In recent years, a variety of new kinase inhibitors have been designed that target various components of the BCR signaling pathway. Targets primarily include phosphatidylinositol 3'kinase (PI3K) and Bruton's tyrosine kinase (BTK). All of these new drugs share a response pattern that results in nodal reduction and increased lymphocytosis, reflecting modulation of the microenvironment, which could prevent these cells from receiving survival signals emitted by the microenvironment. More importantly, these drugs appear to be able to bypass p53 deletion, raising the possibility that they may target existing proliferative pools in the bone marrow and lymph nodes, thus bringing therapy closer to curing p53. disease.

The treatment of chronic lymphatic leukemia (CLL) represents the paradigm of advances in the therapy of hematological neoplasms. In its beginnings, CLL therapy used monodrugs that gradually led to their combination in duplets and triplets with which results never before obtained were achieved. The development of Ibrutinib was probably the milestone that marked the importance of the signaling pathways of leukemic cells in the progression of the disease, opening the investigation of new target drugs that constitute the basis of current treatment in CLL.

The treatment paradigm changes with the approval of BTK (Bruton tyrosine kinase) (iBTK) inhibitors in patients with del17p and/or TP53 (MTP53) mutations, which have achieved overall survival results that have never been achieved before. Quickly after the randomized study of the first-generation iBKT Ibrutinib (I) vs Cl (Resonate 2), this iBTK achieved approval for first-line treatment in all patients. Shortly thereafter, the second generation iBTK acalabrutinib (A) is approved. In June 2020, the National Cancer Center Net (NCCN) guidelines place these agents as preferred in the initial treatment of CLL and make them the agents of choice among North American experts.

According to the study by Mato based on 197 patients, parity in DFS and OS between one group and another has been shown when the ibrutinib dose is reduced. In more than half of the cases, the dose reduction was by medical decision even in the absence of adverse effects.

No significant differences in the saturation point of the BTK receptor with good clinical response with reduced dose are observed in a pharmacokinetic and pharmacodynamic study carried out by Advani et al.

Chen et al carried out a pilot study on 11 patients reducing the dose in 3 phases starting with the standard, a second phase with 280mg/day and a third at 140mg/day, comparing plasmatic and intracellular pharmacokinetics and the occupation of BTK together with the response pharmacodynamics, showing that the lowest dose was sufficient to occupy >95% of the BTK receptor and inhibit the downstream BTK signal.

Despite the improvements in outcomes for patients with poor-prognosis Chronic Lymphocytic Leukemia seen with ibrutinib, these patients are rarely cured. To further improve the results obtained, reduce the toxicity generated from prolonged treatment and reduce the costs of therapy, this protocol is proposed based on a dose adapted to the response to personalized treatment in each patient who meets the initial criteria. of treatment.

This is a prospective, open-label, multicenter, uncontrolled phase II study to evaluate the response to reduced doses of ibrutinib after achieving complete hematologic response or persistent partial response (for 3 or more months), in patients diagnosed with CLL with criteria treatment, first line or relapsed / refractory.

The study design consists of 2 phases:

PHASE I: Treatment with Ibrutinib 420mg/day (3 capsules). Laboratory controls, physical examination with cardiological evaluation will be performed every 14 days during the first 3 months, then every 3 months.

PHASE II: Upon achieving complete hematologic or sustained partial remission for more than 3 months, the Ibrutinib dose is reduced to 280 mg per day (2 capsules). Controls will be carried out every 2 months for 6 months. If complete/partial response is sustained, continue with checkups every 3 months.

Patients who reach phase II, at 6 months, CFM will be performed in peripheral blood. If MRD is negative, CFM should be performed on the bone marrow.