Results of a phase II study of lenalidomide and rituximab for refractory/relapsed chronic lymphocytic leukemia

Targeting the tumor microenvironment for treating double-refractory chronic lymphocytic leukemia

ABSTRACT

The introduction of BTK inhibitors and BCL2 antagonists to the treatment of chronic lymphocytic leukemia (CLL) has revolutionized therapy and improved patient outcomes. These agents have replaced chemoimmunotherapy as standard of care. Despite this progress, a new group of patients is currently emerging, which has become refractory or intolerant to both classes of agents, creating an unmet medical need. Here, we propose that the targeted modulation of the tumor microenvironment provides new therapeutic options for this group of double-refractory patients. Furthermore, we outline a sequential strategy for tumor microenvironment-directed combination therapies in CLL that can be tested in clinical protocols.

Maintenance low-dose fixed duration lenalidomide and rituximab following bendamustine and rituximab induction in previously untreated chronic lymphocytic leukemia and small lymphocytic lymphoma

Lenalidomide (LEN) and rituximab (RTX) have independently improved progression-free survival (PFS) in CLL, leading to interest in use of LEN + RTX (R2) following induction chemoimmunotherapy. Patients with previously untreated CLL received bendamustine + RTX (BR) for 6 cycles, then 24 cycles of R2. LEN dosing was 5-10 mg daily; RTX was given odd cycles (12 doses). The primary endpoint is PFS; secondary endpoints are response and overall survival. Thirty-six patients enrolled, median age 64.5 years. Twenty-nine received R2; 12 completed a full course R2 (33.3%), 5 completed R2 with premature discontinuation of LEN. Dose reductions/holds were most often for neutropenia. Complete response was achieved in 33.3%. After median >4 years follow-up, 2-year and 3-year PFS were 86.1% and 69.4%. Five-year overall survival was 92.3%. R2 maintenance may improve PFS after BR induction, and a lower dose of 5 mg/day and ≤1 year of R2 may be most tolerable (NCT00974233).

Long-term follow up of the combination of ofatumumab, high-dose methylprednisolone, and lenalidomide for untreated chronic lymphocytic leukemia with biomarker analysis

BACKGROUND

Advancements in frontline therapy and chemotherapy-sparing treatments in chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) have altered the treatment algorithms of this disease. We present a frontline alternative for treatment- naïve (TN) CLL/SLL patients.

METHODS

This was a single-center, phase 2 study of high-dose methylprednisolone (HDMP) and ofatumumab with lenalidomide and ofatumumab consolidative therapy for all comers with TN CLL/SLL. Treatment was continued until disease progression or intolerable side effects. Patients were assessed for response per iwCLL 2008 criteria after completing cycles 3 and 12.

RESULTS

Forty-five patients were enrolled (median age, 62.6 years). High-risk features included del17p (18%), Del11q (22%), and unmutated IGHV gene (76%). Median treatment duration was 32·2 (2·7-75·9) months. Thirty-six patients discontinued treatment due to disease progression (22%), adverse events (40%), allogeneic hematopoietic cell transplantation (allo-HCT) (7%), consent withdrawal (4%), and secondary malignancies (7%). The best overall and complete response rates were 96& and 29% respectively. At median follow-up of 61·7 (5·6-84·9) months, 9 patients remained on treatment. Median progression-free survival was 54·4 (2·9-77·6) months. Three patients underwent allo-HCT after a median of 3 (3-4) treatment cycles. Treatment was well tolerated, with a grade 3/4 infusion reaction in one patient. The most common grade 3/4 hematological adverse event was neutropenia (69%). Four patients had grade 3/4 infections. No grade 3/4 tumor flares, tumor lysis syndrome, or thrombosis were observed.

CONCLUSION

The combination of ofatumumab, HDMP, and lenalidomide was effective and relatively well tolerated in treatment-naive CLL/SLL. Its role in the frontline setting remains unclear given the current available and effective treatment options.

FUNDING

The funders had no role in the study.

Current Therapeutic Sequencing in Chronic Lymphocytic Leukemia

The treatment landscape of chronic lymphocytic leukemia (CLL), the most frequent leukemia in adults, is constantly changing. CLL patients can be divided into three risk categories, based on their IGHV mutational status and the occurrence of TP53 disruption and/or complex karyotype. For the first-line treatment of low- and intermediate-risk CLL, both the BCL2 inhibitor venetoclax plus obinutuzumab and the second generation BTK inhibitors (BTKi), namely acalabrutinib and zanubrutinib, are valuable and effective options. Conversely, venetoclax-based fixed duration therapies have not shown remarkable results in high-risk CLL patients, while continuous treatment with acalabrutinib and zanubrutinib displayed favorable outcomes, similar to those obtained in TP53 wild-type patients. The development of acquired resistance to pathway inhibitors is still a clinical challenge, and the optimal treatment sequencing of relapsed/refractory CLL is not completely established. Covalent BTKi-refractory patients should be treated with venetoclax plus rituximab, whereas venetoclax-refractory CLL may be treated with second generation BTKi in the case of early relapse, while venetoclax plus rituximab might be used if late relapse has occurred. On these grounds, here we provide an overview of the current state-of-the-art therapeutic algorithms for treatment-naïve patients, as well as for relapsed/refractory disease.

Obinutuzumab, High-Dose Methylprednisolone (HDMP), and Lenalidomide for the Treatment of Patients with Richter's Syndrome

Background: For patients with Richter's Syndrome (RS), a durable response is rarely achieved with standard therapies. Significant efforts have focused on the development of novel treatments with reduced toxicity. We describe our experience using the novel combination of obinutuzumab, high-dose methylprednisolone (HDMP) and lenalidomide (len) in patients with RS. Patients and Methods: Eligible patients included adults with biopsy-proven RS. Patients received obinutuzumab 1000 mg × 8 doses. All patients received HDMP 1000 mg/m² on days 1-5 of cycles 1-4. Patients were administered len PO daily, starting at a dose of 5 mg. Starting on C2D1, the dose increased every 2 weeks in 5 mg increments to a maximum of 25 mg PO daily. Results: Seven patients were treated. The median dose of len was 10 mg and the median number of cycles of treatment completed was 2. The most common grade 3/4 adverse events were neutropenia (29%) and pulmonary embolism (29%). The overall response rate for the entire cohort was 43% (95% CI, 10-82%). All patients who achieved a response underwent consolidative autologous or allogeneic stem cell transplant and remain in remission to date. Conclusions: The combination of obinutuzumab, HDMP, and len is a well-tolerated, outpatient regimen that could serve as a bridge to transplantation, or as palliation for transplant-ineligible patients with RS.

Immunomodulatory Drugs for the Treatment of B Cell Malignancies

Accumulating evidence suggests that the tumor microenvironment (TME) is involved in disease progression and drug resistance in B cell malignancies, by supporting tumor growth and facilitating the ability of malignant cells to avoid immune recognition. Immunomodulatory drugs (IMiDs) such as lenalidomide have some direct anti-tumor activity, but critically also target various cellular compartments of the TME including T cells, NK cells, and stromal cells, which interfere with pro-tumor signaling while activating anti-tumor immune responses. Lenalidomide has delivered favorable clinical outcomes as a single-agent, and in combination therapy leads to durable responses in chronic lymphocytic leukemia (CLL) and several non-Hodgkin lymphomas (NHLs) including follicular lymphoma (FL), diffuse large B cell lymphoma (DLBCL), and mantle cell lymphoma (MCL). Recently, avadomide, a next generation cereblon E3 ligase modulator (CELMoD), has shown potent anti-tumor and TME immunomodulatory effects, as well as promising clinical efficacy in DLBCL. This review describes how the pleiotropic effects of IMiDs and CELMoDs could make them excellent candidates for combination therapy in the immuno-oncology era-a concept supported by preclinical data, as well as the recent approval of lenalidomide in combination with rituximab for the treatment of relapsed/refractory (R/R) FL.

Efficacy and predictors of response of lenalidomide and rituximab in patients with treatment-naive and relapsed CLL

This phase 2 study was conducted to prospectively evaluate how clinical and biological factors correlate with outcome in patients with treatment-naive (TN) and relapsed (R) chronic lymphocytic leukemia (CLL) treated with lenalidomide and rituximab. Oral lenalidomide 10 mg was administered daily starting on day 9 of cycle 1. IV rituximab 375 mg/m² was administered weekly during cycle 1 and every 4 weeks for cycles 3 to 12. Sequencing of a custom panel of 295 genes was performed in pretreatment bone marrow samples. The study included 61 patients with TN CLL and 59 with R CLL; the overall response rate (ORR) was 73% and 64%, respectively. A baseline β₂-microglobulin level <4 mg/L was associated with higher ORR in both groups (both, P = .03), and absence of mutations in the NOTCH signaling pathway showed a trend for association with higher ORR in R CLL (P = .10). Median PFS was 50 months in TN patients and 28 months in R patients. On multivariate analysis, age ≥65 years (P = .02) was associated with shorter PFS in TN patients, whereas according to univariate analysis, >2 previous therapies (P = .02) was the only factor associated with shorter PFS in R patients. A trend for association between mutations in the NOTCH pathway and shorter PFS was observed in TN CLL (P = .15). Further exploration of the NOTCH pathway may help optimize the efficacy of this combination in patients with CLL. This study protocol was approved by the University of Texas MD Anderson Cancer Center institutional review board and registered at clinicaltrials.gov (#NCT01446133).

A phase 1 study of lenalidomide and ibrutinib in combination with rituximab in relapsed and refractory CLL

Attempts to improve upon the activity of ibrutinib in chronic lymphocytic leukemia (CLL) include the addition of targeted therapies. The combination of lenalidomide and rituximab demonstrated an overall response rate (ORR) of 66% with a complete response (CR) of 12% in the relapsed/refractory setting. Based on these data, we conducted a phase 1 study of rituximab (R), lenalidomide (L), and ibrutinib (I) in relapsed/refractory CLL. Patients received R 375 mg/m² cycles 1 to 6 day 1, L on cycles 1 to 12 days 1 to 21, and I until disease progression. Dose escalation used a standard 3+3 design from a dose level (DL) of L 5 mg (DL1) and increasing to 15 mg (DL3) for a total of 3 dose levels. Twelve patients were enrolled; there were 2 dose-limiting toxicities of grade 4 neutropenia at DL3; thus, DL2 was the recommended phase 2 dose. A high incidence of sustained grade 4 neutropenia occurred at all dose levels, prompting study withdrawal in 5 patients, despite growth factor support. The ORR was 67%; ORR at the RP2D was 100% (1 CR). The 12-month progression-free survival at the RP2D was 83%. Preliminary efficacy data with the triplet did not appear superior to prior reports of the rituximab-lenalidomide doublet or single-agent ibrutinib. Given these findings and the sustained neutropenia, this regimen was not pursued. The study was registered at www.clinicaltrials.gov as #NCT02200848.

Venous thromboembolism in patients with non-Hodgkin lymphoma or chronic lymphocytic leukemia treated with lenalidomide: a systematic review

Lenalidomide has been associated with an increased risk of venous thromboembolism (VTE) in multiple myeloma. It is unclear whether patients with non-Hodgkin lymphoma (NHL) and chronic lymphocytic leukemia (CLL) are also at such risk. We conducted a systematic review of the incidence of VTE in prospective trials of lenalidomide-treated patients with NHL or CLL. Sixty-eight unique reports were assessed for inclusion. For grade ≥3 VTE, 98 events were reported in 3043 patients (60 studies) (crude incidence: 3.22% [95% confidence interval: 2.6-3.9%]). For any grade VTE, 97 events were reported in 2244 patients (46 studies) (crude incidence: 4.32% [3.5-5.2%]). Subgroup analysis showed no difference based on histological subtype or use of prophylaxis. The study is at risk of bias, largely due to insufficient data from the individual studies. Within the limitations of this systematic review, we found a low risk of VTE in patients with NHL treated with lenalidomide.

Increased SHISA3 expression characterizes chronic lymphocytic leukemia patients sensitive to lenalidomide

Lenalidomide is a therapeutically effective drug in chronic lymphocytic leukemia (CLL). Twenty-seven CLL patients were treated with lenalidomide in a phase II clinical trial. Ten patients were grouped as responders (R) and 6 as nonresponders (NR). We evaluated T lymphocytes, NK, monocytes and dendritic cells at baseline and after treatment. A gene expression analysis was performed on 16 CLL samples collected before treatment. The levels of immune cells or immune-related cytokines are not different between R and NR patients. However, CLL patients sensitive to lenalidomide clearly show a peculiar gene expression profile in leukemic cells. The most up-regulated gene (fold change =  +23 in R vs. NR) is Wnt inhibitor SHISA homolog 3 (SHISA3). SHISA3^highCLL are characterized by a restrained activation of Wnt signaling and sensibility to lenalidomide-induced apoptosis. In conclusion, SHISA3 is a candidate gene for the identification of CLL patients who will benefit of lenalidomide treatment as single agent.

NK cell dysfunction in chronic lymphocytic leukemia is associated with loss of the mature cells expressing inhibitory killer cell Ig-like receptors

A prospective analysis of natural killer (NK) cell phenotype and function was performed on fresh peripheral blood samples from untreated patients with B-cell chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL). Compared to healthy controls, CD56^dim NK cells in CLL patients displayed reduced expression of the NKG2D activating receptor and increased CD27 expression, which indicates declines in mature cells. In addition, NK cells from CLL patients showed reduced degranulation responses toward transformed B cells alone or with rituximab and were more sensitive to activation-induced cell death. We further noted a striking reduction in the frequency and viability of NK cells expressing the inhibitory killer cell Ig-like receptors (KIR)2DL1 and/or KIR3DL1, which progressed over time in most patients. Comparisons between a CLL patient and healthy monozygotic twin were consistent with our results in the larger cohorts. Functional and biomarker alterations were less pronounced on NK cells from SLL patients, which have lower tumor burden in peripheral blood than CLL, but significant reduction in degranulation under ADCC conditions and lower frequency and viability of KIR-expressing NK cells were still evident in SLL. We conclude that mature KIR-expressing NK cells respond to the high circulating B cell tumor burden in CLL, but undergo activation-induced apoptosis. Consequently, CLL patients may benefit from therapies that augment NK cell survival and function.

Lenalidomide in the treatment of chronic lymphocytic leukemia

INTRODUCTION

Lenalidomide is an immunomodulatory drug (IMiD) with a unique mode of action (MOA) that may vary across disease-type. It is currently approved in multiple myeloma (MM), myelodysplastic syndrome (MDS) and mantle cell lymphoma (MCL), yet is also clinically active in a host of lymphoproliferative diseases, including chronic lymphocytic leukemia (CLL). Due to its protean effects on the immune system, lenalidomide may be particularly appealing in CLL, which is distinct in its ability to evade immune recognition and cause immunosuppression. Areas covered: This review recaps the biological mechanisms of lenalidomide specific for CLL, and summarizes the clinical data in previously untreated and relapsed/refractory (R/R) CLL patients, with emphasis on toxicity. Moreover, lenalidomide treatment is put into the context of the highly effective targeted agents that are drastically changing the therapeutic approach in CLL. Expert opinion: Lenalidomide is a potent drug in CLL, both in first line and relapse. However, in comparison to other newly available agents, lenalidomide has slow onset of efficacy and notable toxicity profile that limits both its single agent use and combinations with chemotherapy. Future trials will hopefully direct our ability to harness lenalidomide MOA to best incorporate it in the rapidly evolving landscape of CLL treatment.

Antibody-dependent cell cytotoxicity: immunotherapy strategies enhancing effector NK cells

Antibody-dependent cellular cytotoxicity (ADCC) is a set of mechanisms that target cells coated with IgG antibodies of the proper subclasses (IgG1 in the human) to be the prey of cell-to-cell cytolysis executed by immune cells expressing FcRIIIA (CD16A). These effectors include not only natural killer (NK) cells but also other CD16⁺ subsets such as monocyte/macrophages, NKT cells or γδ T cells. In cancer therapy, ADCC is exploited by antibodies that selectively recognize proteins on the surface of malignant cells. An approach to enhance antitumor activity is to act on effector cells so they are increased in their numbers or enhanced in their individual (on a cell per cell basis) ADCC performance. This enhancement can be therapeutically attained by cytokines (that is, interleukin (IL)-15, IL-21, IL-18, IL-2); immunostimulatory monoclonal antibodies (that is, anti-CD137, anti-CD96, anti-TIGIT, anti-KIR, anti-PD-1); TLR agonists or by adoptive infusions of ex vivo expanded NK cells which can be genetically engineered to become more efficient effectors. In conjunction with approaches optimizing IgG1 Fc affinity to CD16, acting on effector cells offers hope to achieve synergistic immunotherapy strategies.

Chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL) is a malignancy of CD5+ B cells that is characterized by the accumulation of small, mature-appearing lymphocytes in the blood, marrow and lymphoid tissues. Signalling via surface immunoglobulin, which constitutes the major part of the B cell receptor, and several genetic alterations play a part in CLL pathogenesis, in addition to interactions between CLL cells and other cell types, such as stromal cells, T cells and nurse-like cells in the lymph nodes. The clinical progression of CLL is heterogeneous and ranges from patients who require treatment soon after diagnosis to others who do not require therapy for many years, if at all. Several factors, including the immunoglobulin heavy-chain variable region gene (IGHV) mutational status, genomic changes, patient age and the presence of comorbidities, should be considered when defining the optimal management strategies, which include chemotherapy, chemoimmunotherapy and/or drugs targeting B cell receptor signalling or inhibitors of apoptosis, such as BCL-2. Research on the biology of CLL has profoundly enhanced our ability to identify patients who are at higher risk for disease progression and our capacity to treat patients with drugs that selectively target distinctive phenotypic or physiological features of CLL. How these and other advances have shaped our current understanding and treatment of patients with CLL is the subject of this Primer.

Phase I-II study of lenalidomide and alemtuzumab in refractory chronic lymphocytic leukemia (CLL): effects on T cells and immune checkpoints

This phase I–II study explored safety, immunomodulatory and clinical effects of lenalidomide (weeks 1–16) and alemtuzumab (weeks 5–16) in 23 patients with refractory chronic lymphocytic leukemia. Most patients had Rai stage III/IV disease and were heavily pretreated (median 4 prior therapies), and 61% had del(17p)/del(11q). Eleven of 19 evaluable patients (58%) responded, with a median response duration of 12 months (1–29+); time to progression was short in non-responders. Lenalidomide had a narrow therapeutic dose range, 2.5 mg/day was not efficient, and maximum tolerated dose was 5 mg/day. Grade 3–4 neutropenia and thrombocytopenia occurred in 84 and 55%, 30% had febrile neutropenia, and CMV-reactivation requiring valganciclovir occurred in 30% of patients. The frequency of proliferating (Ki67⁺) CD8⁺ T cells was increased at week 4, with further increase in both the CD4⁺ and CD8⁺ subsets (p < 0.01 and <0.05), which was accompanied by significant upregulation of HLA-DR after addition of alemtuzumab. Antigen-experienced cells increased at week 4 as the frequency of effector memory cells increased in the CD8⁺ subset (p < 0.003), while effector cells decreased in both the CD8⁺ and CD4⁺ subsets (p < 0.0001 and p < 0.01). The Th1/Th2 balance was unchanged at week 4 but shifted toward a Th2 profile after combination therapy. At end of treatment, the frequency of Th17 and regulatory T cells was reduced (p < 0.01), naïve T cells decreased, and effector memory T cells increased (p < 0.05 and p < 0.01). Granzyme B⁺ T cells increased at 30-week follow-up (p < 0.05). PD-1 expression was unaffected. In conclusion, low-dose lenalidomide and alemtuzumab induced major perturbations of T cells, including increased proliferative activity and cytotoxic potential.