Selecting Frontline Therapy for CLL in 2018

Ibrutinib Does Not Impact CCR7-Mediated Homeostatic Migration in T-Cells from Chronic Lymphocytic Leukemia Patients

Bruton's tyrosine kinase inhibitor ibrutinib has significantly changed treatment landscape in chronic lymphocytic leukemia (CLL). Growing evidence supports ibrutinib to work beyond the effect on tumor cells by means of, for example, restoring functionality of the T-cell compartment and increasing circulating T-cell numbers. Recent evidence suggests T-cell enhanced expansion, rather than increased egress from secondary lymphoid organs (SLO), as a root cause for ibrutinib-induced lymphocytosis. However, whether the latter physiological change is also a consequence of a forced retention in blood remains undisclosed. Since CCR7 is the main chemokine receptor taking over the homing of T-cells from peripheral compartments to lymph nodes and other SLO, we aimed to investigate the impact of ibrutinib on CCR7 functionality in T-cells. To this end, we documented receptor expression in T-cells from a large cohort of ibrutinib-treated CLL patients, and performed different in vivo and in vitro migration models. Overall, our data confirm that CCR7 expression or receptor-mediated migration in CLL T-cells is not affected by ibrutinib. Furthermore, it does not modulate CCR7-driven homing nor nodal interstitial migration. Together, our results support that ibrutinib-induced CLL T-cell accumulation in the blood stream is not derived from an impairment of CCR7-driven recirculation between the SLO and bloodstream, and therefore T-cell expansion is the most plausible cause.

Bendamustine versus chlorambucil in treatment of chronic lymphocytic leukaemia in China: a randomized, open-label, parallel-controlled, phase III clinical trial

BACKGROUND

Chronic lymphoblastic leukemia (CLL) is the most common adult leukemia and mainly affects the elderly. Chemoimmunotherapy still has a role in the standard frontline therapy for specific population. However, the clinical activity of bendamustine has not been investigated in unfit Chinese patients with CLL. This study aimed to compare the efficacy and safety of bendamustine versus chlorambucil for untreated Chinese patients with Binet stage B/C CLL.

METHODS

In this multi-center, randomized, open-label, parallel-controlled, phase III trial, patients with previously untreated CLL were enrolled and randomly assigned (1:1) to receive bendamustine or chlorambucil. The primary endpoint was the objective response rate. Secondary endpoints included progression-free survival, the duration of response, and overall survival. Adverse events were recorded to evaluate safety.

RESULTS

Of 158 screened patients, 147 were enrolled and randomly allocated to receive bendamustine (n = 72) or chlorambucil (n = 75). After a median follow-up of 25.6 months (IQR 12.5-27.7), 69.0% (95% CI, 56.9-79.5) of bendamustine-treated patients achieved objective response and 37.0% (95% CI, 26.0-49.1) of chlorambucil with a difference of 32.0% (95%CI: 16.6-47.5), demonstrating the superiority of bendamustine to chlorambucil (p < 0.001). The median progression-free survival was longer for bendamustine (16.5 months; 95% CI, 11.3-24.7) versus chlorambucil (9.6 months; 95% CI, 8.7-11.8; p < 0.001). A longer median duration of response was seen in those receiving bendamustine (19.2 months; 95% CI, 11.8-29.1) than chlorambucil (10.7 months; 95% CI, 5.6-13.6; p = 0.0018). Median overall survival was not reached in either group. Overall survival at 18 months was 88% for bendamustine versus 85% for chlorambucil. Most common adverse events in both groups were neutropenia and thrombocytopenia.

CONCLUSION

In untreated Chinese patients with Binet stage B/C CLL, bendamustine induced the better objective response and resulted in longer progression-free survival than chlorambucil. Overall, these results validate the role of bendamustine as an effective and safe first-line therapy in this population.

Ibrutinib, fludarabine, cyclophosphamide, and obinutuzumab (iFCG) regimen for chronic lymphocytic leukemia (CLL) with mutated IGHV and without TP53 aberrations

Chemoimmunotherapy with combined fludarabine, cyclophosphamide and rituximab (FCR) has been an effective treatment for patients with chronic lymphocytic leukemia (CLL). We initiated a phase II trial for previously untreated patients with CLL with mutated IGHV and absence of del(17p)/TP53 mutation. Patients received ibrutinib, fludarabine, cyclophosphamide, and obinutuzumab (iFCG) for three cycles. Patients who achieved complete remission (CR)/CR with incomplete count recvoery (CRi) with marrow undetectable measurable residual disease (U-MRD) received additional nine cycles of ibrutinib with three cycles of obinutuzumab; all others received nine additional cycles of ibrutinib and obinutuzumab. Patients in marrow U-MRD remission after cycle 12 discontinued all treatment, including ibrutinib. Forty-five patients were treated. The median follow-up is 41.3 months. Among the total 45 treated patients, after three cycles, 38% achieved CR/CRi and 87% achieved marrow U-MRD. After cycle 12, the corresponding numbers were 67% and 91%, respectively. Overall, 44/45 (98%) patients achieved marrow U-MRD as best response. No patient had CLL progression. The 3-year progression-free survival (PFS) and overall survival (OS) were 98% and 98%, respectively. Per trial design, all patients who completed cycle 12 discontinued ibrutinib, providing for a time-limited therapy. Grade 3-4 neutropenia and thrombocytopenia occurred in 58% and 40% patients, respectively. The iFCG regimen with only 3 cycles of chemotherapy is an effective, time-limited regimen for patients with CLL with mutated IGHV and without del(17p)/TP53 mutation.

Effect of ibrutinib on CCR7 expression and functionality in chronic lymphocytic leukemia and its implication for the activity of CAP-100, a novel therapeutic anti-CCR7 antibody

CAP-100 is a novel therapeutic antibody directed against the ligand binding site of human CCR7. This chemokine receptor is overexpressed in chronic lymphocytic leukemia (CLL) and orchestrates the homing of CLL cells into the lymph node. Previous studies, on a very limited number of samples, hypothesized that the Bruton's tyrosine kinase inhibitor (BTKi) ibrutinib might induce loss of surface CCR7 levels in CLL cells. CAP-100 will be evaluated in clinical trials as a therapy for relapse/refractory CLL patients, who have received at least two systemic therapies (NCT04704323). As nowadays many relapse/refractory CLL patients will have received ibrutinib as a prior therapy, we aimed to investigate in a large cohort of CLL patients the impact of this BTKi on CCR7 expression and functionality as well as on the therapeutic activity of CAP-100. Our data confirm that ibrutinib moderately down-regulates the very high expression of CCR7 in CLL cells but has no apparent effect on CCR7-induced chemotaxis. Moreover, CLL cells are perfectly targetable by CAP-100 which led to a complete inhibition of CCR7-mediated migration and induced strong target cell killing through antibody-dependent cell-mediated cytotoxicity, irrespective of previous or contemporary ibrutinib administration. Together, these results validate the therapeutic utility of CAP-100 as a next-line single-agent therapy for CLL patients who failed to ibrutinib and confirm that CAP-100 and ibrutinib have complementary non-overlapping mechanisms of action, potentially allowing for combination therapy.

Targeting cancer homing into the lymph node with a novel anti-CCR7 therapeutic antibody: the paradigm of CLL

Lymph node (LN) is a key tissue in the pathophysiology of mature blood cancers, especially for chronic lymphocytic leukemia (CLL). Within the multiple de-regulated pathways affecting CLL homeostasis, the CC-chemokine receptor 7 (CCR7) grants homing of CLL cells into the LN where protective environments foster tumor progression. To cover the lack of specific therapies targeting the CCR7-dependence of CLL to enter into the LN, and aiming to displace the disease from LN, we generated CAP-100, an antibody that specifically binds to hCCR7 and neutralizes its ligand-binding site and signaling. In various in vitro and in vivo preclinical models CAP-100 strongly inhibited CCR7-induced migration, extravasation, homing, and survival in CLL samples. Moreover, it triggered potent tumor cell killing, mediated by host immune mechanisms, and was effective in xenograft models of high-risk disease. Additionally, CAP-100 showed a favorable toxicity profile on relevant hematopoietic subsets. Our results validated CAP-100 as a novel therapeutic tool to prevent the access of CLL cells, and other neoplasia with nodal-dependence, into the LN niches, thus hitting a central hub in the pathogenesis of cancer. The first-in-human clinical trial (NCT04704323), which will evaluate this novel therapeutic approach in CLL patients, is pending.

Of Lymph Nodes and CLL Cells: Deciphering the Role of CCR7 in the Pathogenesis of CLL and Understanding Its Potential as Therapeutic Target

The lymph node (LN) is an essential tissue for achieving effective immune responses but it is also critical in the pathogenesis of chronic lymphocytic leukemia (CLL). Within the multitude of signaling pathways aberrantly regulated in CLL the homeostatic axis composed by the chemokine receptor CCR7 and its ligands is the main driver for directing immune cells to home into the LN. In this literature review, we address the roles of CCR7 in the pathophysiology of CLL, and how this chemokine receptor is of critical importance to develop more rational and effective therapies for this malignancy.

Syngeneic leukemia models using lentiviral transgenics

Animal models are necessary to study cancer and develop treatments. After decades of intensive research, effective treatments are available for only a few types of leukemia, while others are currently incurable. Our goal was to generate novel leukemia models in immunocompetent mice. We had achieved abilities for overexpression of multiple driving oncogenes simultaneously in normal primary cells, which can be transplanted and followed in vivo. Our experiments demonstrated the induction of primary malignant growth. Leukemia lines that model various types of leukemia, such as acute myeloid leukemia (AML) or chronic lymphocytic leukemia (CLL), were passaged robustly in congenic wild-type immunocompetent mice. These novel leukemia lines, which may complement previous models, offer the flexibility to generate tailored models of defined oncogenes of interest. The characterization of our leukemia models in immunocompetent animals can uncover the mechanisms of malignancy progression and offer a unique opportunity to stringently test anti-cancer chemotherapies.

Ibrutinib in B-cell lymphoma: single fighter might be enough?

Background

In recent years, the B cell receptor (BCR) signaling pathway has become a "hot point" because it plays a critical role in B-cell proliferation and function. Bruton's tyrosine kinase (BTK) is overexpressed in many subtypes of B-cell lymphoma as a downstream kinase in the BCR signaling pathway. Ibrutinib, the first generation of BTK inhibitor, has shown excellent antitumor activity in both indolent and aggressive B-cell lymphoma.

Main body

Ibrutinib monotherapy has been confirmed to be effective with a high response rate (RR) and well-tolerated in many B-cell lymphoma subgroups. To achieve much deeper and faster remission, combination strategies contained ibrutinib were conducted to evaluate their synergistic anti-tumor effect.

Conclusions

For patients with indolent B-cell lymphoma, most of them respond well with ibrutinib monotherapy. Combination strategies contained ibrutinib might be a better choice to achieve deeper and faster remission in the treatment of aggressive subtypes of B-cell lymphoma. Further investigations on the long-term efficacy and safety of the ibrutinib will provide novel strategies for individualized treatment of B-cell lymphoma.

Efficacy of bendamustine and rituximab in unfit patients with previously untreated chronic lymphocytic leukemia. Indirect comparison with ibrutinib in a real-world setting. A GIMEMA-ERIC and US study

Limited information is available on the efficacy of front‐line bendamustine and rituximab (BR) in chronic lymphocytic leukemia (CLL) with reduced renal function or coexisting conditions. We therefore analyzed a cohort of real‐world patients and performed a matched adjusted indirect comparison with a cohort of patients treated with ibrutinib. One hundred and fifty‐seven patients with creatinine clearance (CrCl) <70 mL/min and/or CIRS score >6 were treated with BR. The median age was 72 years; 69% of patients had ≥2 comorbidities and the median CrCl was 59.8 mL/min. 17.6% of patients carried TP53 disruption. The median progression‐free survival (PFS) was 45 months; TP53 disruption was associated with a shorter PFS (P = 0.05). The overall survival (OS) at 12, 24, and 36 months was 96.2%, 90.1%, and 79.5%, respectively. TP53 disruption was associated with an increased risk of death (P = 0.01). Data on 162 patients ≥65 years treated with ibrutinib were analyzed and compared with 165 patients ≥65 years treated with BR. Factors predicting for a longer PFS at multivariable analysis in the total patient population treated with BR and ibrutinib were age (HR 1.06, 95% CI 1.02‐1.10, P < 0.01) and treatment with ibrutinib (HR 0.55, 95% CI 0.33‐0.93, P = 0.03). In a post hoc analysis of patients in advanced stage, a significant PFS advantage was observed in patient who had received ibrutinib (P = 0.03), who showed a trend for OS advantage (P = 0.08). We arrived at the following conclusions: (a) BR is a relatively effective first‐line regimen in a real‐world population of unfit patients without TP53 disruption, (b) ibrutinib provided longer disease control than BR in patients with advanced disease stage.

Ibrutinib and Venetoclax for First-Line Treatment of CLL

BACKGROUND

Ibrutinib, an inhibitor of Bruton's tyrosine kinase, and venetoclax, an inhibitor of B-cell lymphoma 2 protein, have been approved for patients with chronic lymphocytic leukemia (CLL). Preclinical investigations have indicated potential synergistic interaction of their combination.

METHODS

We conducted an investigator-initiated phase 2 study of combined ibrutinib and venetoclax involving previously untreated high-risk and older patients with CLL. All patients had at least one of the following features: chromosome 17p deletion, mutated TP53, chromosome 11q deletion, unmutated IGHV, or an age of 65 years or older. Patients received ibrutinib monotherapy (420 mg once daily) for 3 cycles, followed by the addition of venetoclax (weekly dose escalation to 400 mg once daily). Combined therapy was administered for 24 cycles. Response assessments were performed according to International Workshop on Chronic Lymphocytic Leukemia 2008 criteria. Minimal residual disease was assessed by means of multicolor flow cytometry in bone marrow (sensitivity, 10-4).

RESULTS

A total of 80 patients were treated. The median age was 65 years (range, 26 to 83). A total of 30% of the patients were 70 years of age or older. Overall, 92% of the patients had unmutated IGHV, TP53 aberration, or chromosome 11q deletion. With combined treatment, the proportions of patients who had complete remission (with or without normal blood count recovery) and remission with undetectable minimal residual disease increased over time. After 12 cycles of combined treatment, 88% of the patients had complete remission or complete remission with incomplete count recovery, and 61% had remission with undetectable minimal residual disease. Responses were noted in older adults and across all high-risk subgroups. Three patients had laboratory evidence of tumor lysis syndrome. The adverse-event profile was similar to what has been reported with ibrutinib and venetoclax.

CONCLUSIONS

In this study, combined venetoclax and ibrutinib was an effective oral regimen for high-risk and older patients with CLL. (Funded by AbbVie and others; ClinicalTrials.gov number, NCT02756897.).