Bruton tyrosine kinase inhibitors for the frontline treatment of chronic lymphocytic leukemia

Chronic lymphocytic leukemia (cll) is the most commonly diagnosed adult leukemia in Canada. Biologic heterogeneity of cll between patients results in variable disease trajectories and responses to therapy. Notably, compared with patients lacking high-risk features, those with such features-such as deletions in chromosome 17p, aberrations in the TP53 gene, or unmutated immunoglobulin heavy chain variable region genes-experience inferior outcomes and responses to standard chemoimmunotherapy. Novel agents that target the B cell receptor signalling pathway, such as Bruton tyrosine kinase (btk) inhibitors, have demonstrated clinical efficacy and safety in patients with treatment-naïve cll, particularly those with high-risk features. However, given the current lack of head-to-head trials comparing btk inhibitors, selection of the optimal btk inhibitor for patients with cll is unclear and requires consideration of multiple factors. In the present review, we focus on the efficacy, safety, and pharmacologic features of the btk inhibitors that are approved or under clinical development, and we discuss the practical considerations for the use of those agents in the Canadian treatment landscape.

Management of chronic lymphocytic leukemia in Canada during the coronavirus pandemic

The emergence of the covid-19 disease pandemic caused by the 2019 novel coronavirus has required a re-evaluation of treatment practices for clinicians caring for patients with chronic lymphocytic leukemia (cll). The American Society for Hematology (ash) has provided a series of recommendations for the treatment of patients with cll during the pandemic, covering a range of topics, including testing for covid-19, cll treatment initiation and selection, use of immunoglobulin therapy, in-person monitoring, and treatment of patients with cll and covid-19. We summarize the ash recommendations and discuss their applicability as guidelines for the treatment of cll during the covid-19 pandemic in Canada.

Emerging therapies for the treatment of relapsed or refractory diffuse large B cell lymphoma

Diffuse large B cell lymphoma (dlbcl) is an aggressive non-Hodgkin lymphoma, accounting for approximately 30% of lymphoma cases in Canada. Although most patients will achieve a cure, up to 40% will experience refractory disease after initial treatment, or relapse after a period of remission. In eligible patients, salvage therapy followed by high-dose therapy and autologous stem-cell transplantation (asct) is the standard of care. However, many patients are transplant-ineligible, and more than half of those undergoing asct will subsequently relapse. For those patients, outcomes are dismal, and novel treatment approaches are a critical unmet need. In this paper, we present available data about emerging treatment approaches in the latter setting and provide a perspective about the potential use of those approaches in Canada.

Review of Bruton tyrosine kinase inhibitors for the treatment of relapsed or refractory mantle cell lymphoma

Mantle cell lymphoma (mcl) is a rare subtype of aggressive B-cell non-Hodgkin lymphoma that remains incurable with standard therapy. Patients typically require multiple lines of therapy, and those with relapsed or refractory (r/r) disease have a very poor prognosis. The Bruton tyrosine kinase (btk) inhibitor ibrutinib has proven to be an effective agent for patients with r/r mcl. Although usually well tolerated, ibrutinib can be associated with unique toxicities, requiring discontinuation in some patients. Effective and well-tolerated alternatives to ibrutinib for patients with r/r mcl are therefore needed. Novel btk inhibitors such as acalabrutinib, zanubrutinib, and tirabrutinib are designed to improve on the safety and efficacy of first-generation btk inhibitors such as ibrutinib. Data from single-arm clinical trials suggest that, compared with ibrutinib, second-generation btk inhibitors have comparable efficacy and might have a more favourable toxicity profile. Those newer btk inhibitors might therefore provide a viable treatment option for patients with r/r mcl.

International Working Group consensus response evaluation criteria in lymphoma (RECIL 2017)

In recent years, the number of approved and investigational agents that can be safely administered for the treatment of lymphoma patients for a prolonged period of time has substantially increased. Many of these novel agents are evaluated in early-phase clinical trials in patients with a wide range of malignancies, including solid tumors and lymphoma. Furthermore, with the advances in genome sequencing, new "basket" clinical trial designs have emerged that select patients based on the presence of specific genetic alterations across different types of solid tumors and lymphoma. The standard response criteria currently in use for lymphoma are the Lugano Criteria which are based on [18F]2-fluoro-2-deoxy-D-glucose positron emission tomography or bidimensional tumor measurements on computerized tomography scans. These differ from the RECIST criteria used in solid tumors, which use unidimensional measurements. The RECIL group hypothesized that single-dimension measurement could be used to assess response to therapy in lymphoma patients, producing results similar to the standard criteria. We tested this hypothesis by analyzing 47 828 imaging measurements from 2983 individual adult and pediatric lymphoma patients enrolled on 10 multicenter clinical trials and developed new lymphoma response criteria (RECIL 2017). We demonstrate that assessment of tumor burden in lymphoma clinical trials can use the sum of longest diameters of a maximum of three target lesions. Furthermore, we introduced a new provisional category of a minor response. We also clarified response assessment in patients receiving novel immune therapy and targeted agents that generate unique imaging situations.

Emerging therapies for the treatment of relapsed or refractory follicular lymphoma

With no treatment standard having been established for relapsed and refractory follicular lymphoma, a number of therapeutic approaches are used in Canada. In patients who relapse early or who eventually become resistant to subsequent treatment, prognosis is poor, and new approaches are needed. A number of novel therapies are being examined in this setting, including monoclonal antibodies, immunoconjugates, immunomodulatory agents, and signal transduction inhibitors. With the body of evidence for those emerging therapies accumulating and the standard upfront treatment changing from rituximab and chop (cyclophosphamide-doxorubicin-vincristine-prednisone) or rituximab and cvp (cyclophosphamide-vincristine-prednisone) to bendamustine and rituximab, treatment decisions in the relapsed and refractory setting have become more complex. The choice of subsequent treatment must consider type of upfront treatment; duration of remission; and patient-related factors such as age, comorbidities, and treatment preferences. This paper summarizes the evidence for novel therapies and proposes recommendations for subsequent treatment options by remission duration after induction and maintenance.

The value of routine bone marrow biopsy in patients with diffuse large B-cell lymphoma staged with PET/CT: a Danish-Canadian study

BACKGROUND

The added diagnostic and prognostic value of routine bone marrow biopsy (BMB) in patients with diffuse large B-cell lymphoma (DLBCL) undergoing positron emission tomography combined with computed tomography (PET/CT) staging is controversial.

PATIENTS AND METHODS

Patients with newly diagnosed DLBCL who underwent both staging PET/CT and BMB were retrospectively identified in British Columbia, Aalborg, and Copenhagen. Original written PET/CT and pathology reports were retrospectively reviewed to determine Ann Arbor stage and outcomes, with and without the contribution of BMB.

RESULTS

A total of 530 patients were identified: 146 (28%) had focal bone marrow (BM) lesions on PET/CT and 87 (16%) had positive BMB. Fifty-two of 146 patients (36%) with positive PET/CT had a positive BMB [39 DLBCL, 13 indolent non-Hodgkin lymphoma (iNHL)], while 35 of 384 patients (9%) with negative PET/CT had positive BMB (12 DLBCL, 23 iNHL). BMB upstaged 12/209 (6%) of stage I/II patients to stage IV, although this was the case for only 3 (1%) patients with DLBCL in the BMB. PET/CT identified BM involvement by BMB with sensitivity 60%, specificity 79%, positive predictive value 36%, and negative predictive value 91%. Concordant histological involvement of the BM by DLBCL was associated with worse overall survival and progression-free survival than discordant or no involvement in univariate and multivariate analyses.

CONCLUSIONS

In patients with DLBCL, staging PET/CT can miss BM involvement with concordant DLBCL (less common) or discordant iNHL (more common). Routine BMB does not add relevant diagnostic or prognostic value over PET/CT alone in the majority of patients with DLBCL.

Outcome of patients with primary refractory diffuse large B cell lymphoma after R-CHOP treatment

Primary refractory diffuse large B cell lymphoma (DLBCL) following R-CHOP chemotherapy is a major concern. We identified 1126 patients with DLBCL treated with R-CHOP from 2000 to 2009, of whom 166 (15 %) had primary refractory disease. Of the 75/166 (45 %) who were age <70 years and had been planned for stage-directed curative therapy, 43 (57 %) were primary nonresponders and 32 (43 %) relapsed within 3 months of completing R-CHOP. Thirty of 75 (40 %) patients had serious comorbidity and organ dysfunction precluding intensive treatment and had palliative treatment only. Twelve of 45 (27 %) patients responded to second-line treatment and underwent ASCT. The median overall survival for the 75 patients was 10 months with only seven patients alive without evidence of disease at follow-up ranging from 14 to 106 months. Primary refractory DLBCL after R-CHOP has a very poor outcome with only anecdotal survivors independent of the intended treatment approach.

A Canadian perspective on bendamustine for the treatment of chronic lymphocytic leukemia and non-Hodgkin lymphoma

Despite the success of standard treatments in chronic lymphocytic leukemia (CLL) and non-Hodgkin lymphoma (NHL), patients are often unable to tolerate aggressive regimens, and they require effective alternatives. Bendamustine is a bifunctional alkylator with unique properties that significantly distinguish it from other agents in its class. In untreated CLL, bendamustine has demonstrated rates of response and progression-free survival (PFS) that are superior to those with chlorambucil, with an acceptable toxicity profile. In the relapsed setting, combination treatment with bendamustine-rituximab (BR) has demonstrated promising activity in high-risk patients such as those refractory to fludarabine or alkylating agents. In untreated patients with indolent NHL and mantle cell lymphoma, BR has demonstrated a PFS significantly longer than that achieved with R-CHOP (rituximab-cyclophosphamide-doxorubicin-vincristine-prednisone), with significantly reduced toxicity. In the relapsed setting, br has demonstrated rates of response and PFS superior to those with fludarabine-rituximab, with comparable toxicity. In the United States and Europe, bendamustine has been approved for the treatment of CLL and indolent NHL; its approval in Canada is pending and eagerly awaited. Once available, bendamustine will benefit many Canadian patients with NHL and CLL.

Incidence and risk factors for central nervous system relapse in patients with diffuse large B-cell lymphoma: The impact of the addition of rituximab to CHOP chemotherapy

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Background: The addition of rituximab to CHOP (CHOP-R) chemotherapy improves outcome in patients with diffuse large B- cell lymphoma (DLBCL). However, limited data suggests that it may not impact the risk of central nervous system (CNS) relapse. We evaluated the risk of CNS relapse and associated predictive factors in a large population-based cohort of patients with DLBCL. Methods: All patients with DLBCL diagnosed from September 1, 1999 to January 14, 2005 at the British Columbia Cancer Agency were identified, including those from a recently published report (Sehn, J Clin Onc. 2005). Patients were included if they were ≥16 years old with advanced stage (stage III /IV, or stage I /II with B symptoms or bulky disease (≥10 cm)), or limited stage with testicular involvement and excluded if HIV-positive or known to have CNS involvement at diagnosis. From Sept 1999 to Feb 2001 patients were treated with CHOP- type chemotherapy. After March 1, 2001 patients received CHOP-R. Results: A total of 435 patients with DLBCL were identified; 125 (29%) were treated with CHOP and 310 (71%) with CHOP-R. There were 28 CNS relapses with no significant difference in frequency between CHOP-treated (11 (9%)) or CHOP-R-treated (17 (5%)) patients (p=0.202). The median time to CNS relapse (8.1 mos vs 6.7 mos) and median survival after CNS relapse (2.7 mos vs 3.8 mos, p=0.665) were similar in the CHOP and CHOP-R treated patients, respectively. In univariate analysis, testicular involvement, renal involvement, advanced stage, and LDH ≥2x ULN were associated with increased risk of CNS relapse. In a multivariate analysis, testicular (OR 7.44, p=0.013) or renal (OR 6.23, p=0.012) involvement, and stage IV disease (OR 4.43, p=0.034) were independent predictors of CNS relapse. Conclusions: Consistent with prior reports, the addition of rituximab does not appear to significantly influence the risk of CNS relapse in patients with DLBCL, possibly due to poor CNS penetration. Risk factors for CNS relapse in the rituximab era are similar to those noted in prior reports based on anthracycline-treated patients. The overall survival of patients with CNS relapse is dismal and new strategies to reduce its incidence warrant further evaluation.

No significant financial relationships to disclose.

A clinicopathological retrospective study of 131 patients with primary bone lymphoma: a population-based study of successively treated cohorts from the British Columbia Cancer Agency

BACKGROUND

Primary bone lymphoma (PBL) is a distinct clinicopathological entity. Although PBL has been reviewed in several small studies, few reflect recent improvements in primary treatment.

METHODS

We used the British Columbia Cancer Agency Lymphoid Cancer Database to identify all patients with PBL (1983-2005). All were staged in a uniform manner and treated with era-specific protocols.

RESULTS

We identified 131 patients with a median age of 63 years (18-87). One third had disease in long bones and another one third had disease in the spine, of which half presented with spinal cord compression. Patients with diffuse large-cell lymphoma (DLCL) (n=103, 79%) had 5- and 10-year overall survivals (OS) of 62% and 41%, respectively. Multivariate analysis identified three prognostic groups: age<60 with International Prognostic Index (IPI) 1-3 (n=43), age>or=60 with IPI 0-3 (n=23) and age>or=60 with IPI 4-5 (n=33), with markedly different 5-year OS of 90%, 61% and 25%, respectively (P<0.0001). Neither primary site nor pathological fracture at presentation had an impact on OS. The 3-year progression-free survival in patients who received rituximab plus combination chemotherapy with cyclophosphamide, doxorubicin, vincristine and prednisone (CHOPR) chemotherapy was 88% compared with 52% in those who received CHOP-like chemotherapy without rituximab (P=0.005). The 10-year OS for those with advanced-stage disease who received irradiation plus chemotherapy was 25% versus 56% for those who received chemotherapy alone (P=0.025). Patients received irradiation if spinal cord compression was present or residual disease at the end of chemotherapy was thought to require it.

CONCLUSIONS

PBL is usually of DLCL type and has an improved outcome with CHOPR. Younger patients with good IPI score have a favorable prognosis.

The impact of initial treatment of advanced stage indolent lymphoma on the risk of transformation

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Background: The impact of initial treatment of indolent non-Hodgkin’s lymphoma (NHL) on the risk of transformation (TR) to aggressive NHL is unknown. High LDH and advanced stage at diagnosis have been shown to be predictive for TR; however, the effect of initial treatment is difficult to estimate as most series included heterogenous patient (pts) populations. Methods: As part of a large retrospective analysis examining TR (n = 698), we identified pts from 2 consecutive phase II studies conducted at the British Columbia Cancer Agency. Both studies had identical inclusion criteria: diagnosis of indolent NHL, no prior treatment, age16–60 y and advanced stage disease (III/ IV or I/ II with B symptoms or bulky disease ≥10cm). The first study included use of BPVACOP (bleomycin, cisplatin, etoposide, doxorubicin, cyclophosphamide,vincristine and prednisone, followed by involved field irradiation (RT) to original nodal sites of lymphoma. The second used combination alkylator-purine analogue (cyclophosphamide- cladrabine or fludaribine and prednisone). The definition of TR was based on either histological confirmation (HIST) or clinical features (CLIN), defined as one or more of the following: rapid discordant nodal or extranodal growth; sudden rise in LDH to > 2 x previous baseline; involvement of unusual extranodal sites; or hypercalcemia. Results: 260 pts were identified. BPVACOP+RT (n = 140), alkylator-purine analogue (n = 120). Median age 46 y (19–60). Follicular histology in 133 (94%) and 105 (87%), respectively. The majority were stage III/IV (89%) with equal proportions in each cohort. With a median follow-up (FU) for living pts of 90 months (1–225), 26 (18%) pts treated with BPVACOP+RT developed TR, 16 of which were confirmed with biopsy, versus 32 (27%) in the alkylator-purine group, of which 18 had biopsy confirmation. The 5 y risk of TR for BPVACOP+RT was 9% compared to 24% for the alkylator-purine analogue group (p < 0.0095). The annual risk of TR through 10 y of FU was 1.5% and 3.0%, respectively. The post-TR 5 y OS of all 58 pts with TR was 19%. Pts with TR based on CLIN vs HIST criteria did not differ in their outcome. Conclusions: The use of an anthracycline-based regimen as initial treatment for advanced stage indolent NHL is associated with a marked reduction in the risk of future TR.

No significant financial relationships to disclose.

Pancreatitis during therapy of acute myeloid leukemia: cytarabine related?

BACKGROUND

Acute pancreatitis in acute myeloid leukemia (AML) has been rarely associated with cytarabine therapy. This report attempts to characterize this toxicity.

PATIENTS AND METHODS

Criteria for pancreatitis was prospectively defined. Seven patients with pancreatitis were identified from an AML database and a clinical study at two tertiary care centers (n = 134). Their records were retrospectively reviewed.

RESULTS

Seven patients with pancreatitis complicating AML therapy were identified. Median age was 36 (range 25-73) years. Median amylase was 184 (range 77-552) U/l and median lipase was 1026 (range 630-6087) U/l. The patients had received high dose bolus cytarabine (2 g/m2 i.v. bolus every 12 hours; n = 2), and continuous infusion cytarabine followed by high-dose cytarabine (100 mg/m2 i.v. CI days 1-7 then 2 g/m2 i.v. bolus every 12 hours days 8-10; n = 2), or standard dose continuous infusion cytarabine (200 mg/m2/d; n = 3) prior to developing pancreatitis. Pancreatitis occurred at a median of 10 days following day one of cytarabine administration with resolution at a median of 11 days after initial diagnosis. Six patients did not suffer major complications. One patient died of causes unrelated to pancreatitis. Five of six patients was rechallenged and all remained free of pancreatitis. One patient subsequently did develop pancreatitis on a later rechallenge.

CONCLUSIONS

Pancreatitis in the setting of AML therapy may be an infrequent and self-limited toxicity of cytarabine. A schedule dependent toxicity with cytarabine was not identified.

Comparative outcomes of T-cell-depleted and non-T-cell-depleted allogeneic bone marrow transplantation for chronic myelogenous leukemia: impact of donor lymphocyte infusion

PURPOSE

Donor lymphocyte infusion (DLI) can restore complete remission in patients with chronic myelogenous leukemia (CML) who have relapsed after T-cell-depleted (TCD) allogeneic bone marrow transplantation (BMT). The existence of salvage treatment for patients with DLI after TCD allogeneic BMT prompted an evaluation of overall outcome after CD6+ -TCD allogeneic BMT for patients treated during the time when DLI has been available.

PATIENTS AND METHODS

We performed a retrospective analysis of outcomes of 46 patients who underwent TCD allogeneic BMT for stable-phase CML and compared these outcomes with those of 40 patients who underwent non-TCD allogeneic BMT. All subjects were patients at one of two neighboring institutions during a period when DLI was available. All patients received marrow from HLA-identical sibling donors, underwent similar myeloablative regimens, and had similar pretreatment characteristics.

RESULTS

After BMT, the TCD group had a lower incidence of grade 2 to 4 acute (15% v 37%, P = .026) and chronic graft-versus-host disease (GVHD) (18% v 42%, P = .024) than did the non-TCD group. The 1-year treatment-related mortality rates for the TCD group and the non-TCD group were 13% and 29%, respectively (P = .07). The estimated 3-year probability of relapse (cytogenetic or hematologic) was higher for patients in the TCD group than for patients in the non-TCD group (62% v 24%, P = .0003). Twenty-three patients (20 in the TCD group and three in the non-TCD group) received and were assessable for response to DLI. After DLI, 17 of 20 patients in the TCD group and two of three patients in the non-TCD group achieved complete remission. Donor lymphocyte infusion induced GVHD in nine of 23 patients. Thirty (65%) of 46 patients in the TCD group and 27 (69%) of 39 assessable patients in the non-TCD group remained alive without evidence of disease. The estimated 3-year overall survival rates were similar for the TCD group and the non-TCD group (72% v 68%, respectively; P = .38). At last follow-up, there was no difference in the overall prevalence of GVHD or the proportion of patients requiring immunosuppressive agents between groups.

CONCLUSION

These results suggest that the combination of T-cell depletion and post-BMT DLI is a viable treatment option for patients undergoing allogeneic BMT for CML and should be prospectively compared with traditional forms of GVHD prophylaxis.

A phase II study of BTI-322, a monoclonal anti-CD2 antibody, for treatment of steroid-resistant acute graft-versus-host disease

BTI-322, a rat monoclonal IgG2b directed against the CD2 antigen on T cells and natural killer (NK) cells, blocks primary and memory alloantigen proliferative responses in vitro. We have evaluated the pharmacokinetics and safety of BTI-322 during treatment of 20 transplant recipients with steroid-refractory acute graft-versus-host disease (GVHD). Treatment consisted of BTI-322 by intravenous (IV) bolus or 30-minute infusion at approximately 0.1 mg/kg/d for 10 days in addition to continuing high-dose steroids and tacrolimus or cyclosporine. Pharmacokinetic sampling was performed in 10 patients; the t1/2 +/- SE was 9.1 +/- 1.3 hours, the Cmax was 2,549 +/- 291 ng/mL, the Vd was 3.97 +/- 0.95 L, and the Vd/kg was 0. 05 +/- 0.01 L/kg. Ten patients experienced transient dyspnea sometimes accompanied by nausea, vomiting, diarrhea, and tachycardia shortly after the initial bolus dose of drug, but serious drug-related adverse events were not seen during the remainder of the infusions. At the end of treatment (day 11), there were six patients with complete responses and five with a reduction in grade of GVHD for a total response rate of 55% (95% confidence interval [CI], 32% to 77%). Antibodies targeting CD2 may be active in the treatment of acute GVHD, and evaluation of a humanized form of BTI-322 is warranted.

Primary diffuse large B-cell lymphoma of the mediastinum: outcome following high-dose chemotherapy and autologous hematopoietic cell transplantation

We performed a retrospective analysis of 35 patients with primary diffuse large B-cell lymphoma of the mediastinum treated with high-dose cyclophosphamide, carmustine, and etoposide (CBV) plus autologous hematopoietic cell transplantation to determine outcome and prognostic features for progression-free survival (PFS). Thirty-five patients with primary diffuse large B-cell lymphoma of the mediastinum in first response (complete remission [CR] or partial remission [PR]) with poor prognostic features, with primarily refractory disease, or with relapsed disease following conventional chemotherapy, were treated with CBV and autologous hematopoietic cell transplantation. PFS and overall survival were assessed by the Kaplan-Meier method. Patient characteristics before transplantation were examined by univariate analysis using the log-rank test and by Cox's proportional hazards regression analysis to determine predictors of PFS. Estimated 5-year PFS varied significantly with patient disease status at transplantation. Patients transplanted in first response had an estimated 5-year PFS rate of 83%, compared with 58% and 27% for primarily refractory and relapsed patients, respectively (P = .02). The strongest predictor of PFS was chemotherapy responsiveness immediately before transplantation. Patients with chemotherapy-responsive disease had a significantly greater PFS rate than patients with chemotherapy-nonresponsive disease (risk ratio, 3.60; 95% confidence interval [CI], 1.14 to 11.4). No other factors were found to be significant on univariate or multivariate analysis. Patients with primary diffuse large B-cell lymphoma of the mediastinum can achieve prolonged PFS following high-dose chemotherapy and autologous hematopoietic cell transplantation. Outcomes are strongly correlated with disease status (first response v refractory v relapsed) at transplantation and chemotherapy responsiveness immediately before transplantation.