Loss of CD20 expression as a mechanism of resistance to mosunetuzumab in relapsed/refractory B-cell lymphomas

ABSTRACT

CD20 is an established therapeutic target in B-cell malignancies. The CD20 × CD3 bispecific antibody mosunetuzumab has significant efficacy in B-cell non-Hodgkin lymphomas (NHLs). Because target antigen loss is a recognized mechanism of resistance, we evaluated CD20 expression relative to clinical response in patients with relapsed and/or refractory NHL in the phase 1/2 GO29781 trial investigating mosunetuzumab monotherapy. CD20 was studied using immunohistochemistry (IHC), RNA sequencing, and whole-exome sequencing performed centrally in biopsy specimens collected before treatment at predose, during treatment, or upon progression. Before treatment, most patients exhibited a high proportion of tumor cells expressing CD20; however, in 16 of 293 patients (5.5%) the proportion was <10%. Analyses of paired biopsy specimens from patients on treatment revealed that CD20 levels were maintained in 29 of 30 patients (97%) vs at progression, where CD20 loss was observed in 11 of 32 patients (34%). Reduced transcription or acquisition of truncating mutations explained most but not all cases of CD20 loss. In vitro modeling confirmed the effects of CD20 variants identified in clinical samples on reduction of CD20 expression and missense mutations in the extracellular domain that could block mosunetuzumab binding. This study expands the knowledge about the occurrence of target antigen loss after anti-CD20 therapeutics to include CD20-targeting bispecific antibodies and elucidates mechanisms of reduced CD20 expression at disease progression that may be generalizable to other anti-CD20 targeting agents. These results also confirm the utility of readily available IHC staining for CD20 as a tool to inform clinical decisions. This trial was registered at www.ClinicalTrials.gov as #NCT02500407.

ROSEWOOD: A Phase II Randomized Study of Zanubrutinib Plus Obinutuzumab Versus Obinutuzumab Monotherapy in Patients With Relapsed or Refractory Follicular Lymphoma

PURPOSE

The combination of zanubrutinib plus obinutuzumab (ZO) was found to be well tolerated with an early signal of efficacy in a phase Ib study. ROSEWOOD is a phase II, randomized study that assessed the efficacy and safety of ZO versus obinutuzumab in patients with relapsed/refractory (R/R) follicular lymphoma (FL).

METHODS

Patients with R/R FL who had received ≥2 lines of therapy, including an anti-CD20 antibody and an alkylating agent, were randomly assigned 2:1 to receive ZO or obinutuzumab (O). The primary end point was overall response rate (ORR) by independent central review (ICR). Secondary end points included duration of response (DOR), progression-free survival (PFS), overall survival, and safety.

RESULTS

A total of 217 patients were randomized (ZO, 145; O, 72). Median study follow-up was 20.2 months. The study met its primary end point: ORR by ICR was 69% (ZO) versus 46% (O; P = .001). Complete response rate was 39% (ZO) versus 19% (O); 18-month DOR rate was 69% (ZO) versus 42% (O). Median PFS was 28.0 months (ZO) versus 10.4 months (O; hazard ratio, 0.50 [95% CI, 0.33 to 0.75]; P < .001). The most common adverse events with ZO were thrombocytopenia, neutropenia, diarrhea, and fatigue; incidences of atrial fibrillation and major hemorrhage were 3% and 1%, respectively.

CONCLUSION

The combination of ZO met its primary end point of a superior ORR versus O, and demonstrated meaningful activity and a manageable safety profile in patients with R/R FL. ZO had a favorable benefit-risk profile compared with O, and represents a potential combination therapy for patients with R/R FL.

Canadian real-world experience of asciminib treatment in heavily pre-treated chronic myeloid leukemia (CML) patients who failed multiple lines of tyrosine kinase inhibitor (TKI) therapy

BACKGROUND

Asciminib is a novel drug specifically targeting ABL myristoyl pocket in the ABL1 protein.

METHODS

Forty one patients with chronic myeloid leukemia treated with asciminib from 2018 to 2022 were reviewed and analyzed for the efficacy and tolerability of asciminib using real-world experience data.

RESULTS

The median age was 60 years (range 17-90) with a past history of a cardiovascular event in 21 patients (51%). Patients were pretreated with a median of 3 previous tyrosine kinase inhibitors (range 1-5). After a median of 12 months of asciminib (range 3-41), major molecular response (MMR) rate was 39% (n = 11/28) and 42% (n = 5/12) at 6 and 12 months, respectively. Molecular response with 2 log reduction (MR2) was noted in 54% (n = 15/28) and 50% (n = 6/12) at 6 and 12 months. The cumulative incidence of MMR and MR2 was 46.3% and 66% at 12 months. Five patients discontinued asciminib due to treatment failure (n = 3) or thrombocytopenia (n = 2). There were no cardiovascular events. Out of 7 patients treated with high dose asciminib for T315I mutation, 5 patients achieved MMR or deeper response. The event-free survival was 63% at 12 months.

CONCLUSION

This study confirmed clinical efficacy and tolerability of asciminib with real-world experience.

Characterization of CD20 expression loss as a mechanism of resistance to mosunetuzumab in patients with relapsed/refractory B-cell non-Hodgkin lymphomas

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Background: Mosunetuzumab (M) is a bispecific antibody targeting CD20 and CD3 that redirects T cells to engage and eliminate malignant B cells being developed for relapsed or refractory (R/R) B-cell non-Hodgkin lymphomas (B-NHL). CD20 is an optimal target, with uniform expression across B-NHL histologies and minimal receptor turnover. We characterized CD20 loss as a potential mechanism of resistance to M in patients (pts) on a Phase I/II trial (NCT02500407) receiving M monotherapy for the treatment (tx) of R/R B-NHL. Methods: Pts with R/R B-NHL received M intravenously in 3-week cycles, for eight to 17 cycles depending on tumor response. At baseline (BL), biomarker-evaluable (archival or fresh) biopsies were collected from 293 pts. Biopsies from 62 pts were collected at additional time points during tx with M and/or at disease progression (PD). The proportion of CD20+ and PAX5+ tumor cells was determined by immunohistochemistry (IHC) using dual-staining with anti-CD20 (clone L26, VENTANA) and anti-PAX5 (clone DAK-PAX5, DAKO) antibodies. Expression of MS4A1, the gene encoding CD20 , was measured by RNA-sequencing (RNA-seq); MS4A1 mutation profiling was performed by whole exome sequencing (WES). Levels of CD20 expression were assessed relative to response rates. Correlative analyses were performed and assessed centrally (IHC, RNA-seq, and WES) and locally (IHC). Results: CD20 levels were consistently high ( > 75% CD20+PAX5+ cells) in the majority of BL biopsies and generally comparable across histologies (FL, DLBCL, tFL, MCL, and RT). BL CD20 loss (≤5% CD20+PAX5+ cells) was seen in 16/293 pts (5.5%), more commonly in aggressive NHL, and responses to M were not seen in these pts. Among 62 pts with BL and on-tx/at-PD biopsies, BL CD20 levels were ≤5% in 7/62 pts (11%) (6/7 pts [86%] progressed before completing Cycle 2). CD20 levels were maintained in on-tx biopsies from 23/24 pts (96%). At PD, biopsies showed CD20 loss in 7/26 pts (27%). For five pts with BL, on-tx and at-PD biopsies, all pts maintained CD20 while on-tx and 1/5 pts (20%) had CD20 loss at PD. There was no clear association between CD20 reduction and histology. Data from 185 BL biopsies showed generally concordant levels of CD20 gene and protein expression (r = 0.72). In 10/185 pts (5%), MS4A1 was expressed without detectable CD20 protein expression; DNA sequencing revealed novel mutations in MS4A1, including mutations leading to truncation of the protein. CD20 transmembrane and extra-cellular domain mutations were also observed but do not block CD20 expression. Conclusions: In pts with R/R B-NHL treated with M, low BL CD20 expression is associated with lack of response to M. During M tx, loss of tumor cell expression of CD20 is one mechanism of acquired resistance; however, CD20 expression is maintained in most pts with PD, implying alternative mechanisms for acquired M resistance. Clinical trial information: NCT02500407.

Zanubrutinib plus obinutuzumab (ZO) versus obinutuzumab (O) monotherapy in patients (pts) with relapsed or refractory (R/R) follicular lymphoma (FL): Primary analysis of the phase 2 randomized ROSEWOOD trial

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Background: FL is the most common type of indolent non-Hodgkin lymphoma. Approved treatment options are limited for pts with R/R FL. In a phase 1b trial ( Blood Adv. 2020;4(19):4802-4811), ZO was found to be tolerable and associated with early signal of efficacy. ROSEWOOD (BGB-3111-212) is a phase 2, randomized study designed to assess efficacy and safety of ZO vs O in pts with R/R FL. Methods: Pts with R/R FL who received ≥2 lines of therapy, including an anti-CD20 antibody and an alkylating agent, were randomized 2:1 to receive either ZO or O. O was given in both arms on Days 1, 8, and 15 of Cycle 1, Day 1 of Cycles 2-6, and then every 8 weeks up to 20 doses maximum. Z (160 mg twice daily) was given until progressive disease (PD) or unacceptable toxicity; Pts with confirmed PD in the O arm were allowed to crossover to ZO. Primary endpoint was overall response rate (ORR) by independent central review. Secondary endpoints included complete response rate (CRR), duration of response (DOR), progression-free survival (PFS), overall survival (OS), and safety. Exploratory endpoint included ORR by investigator after crossover. Primary analysis cutoff was October 8, 2021. Results: A total of 217 pts were randomized to ZO (n = 145) or O (n = 72). Median study follow-up was 12.5 mo; median age was 64 yrs. Incidence of high FL International Prognostic Index score was 53% (ZO) and 51% (O). Pts received a median of 3 prior lines of therapy, with 28% (ZO) and 25% (O) of pts receiving > 3 lines. Proportion of pts refractory to rituximab, refractory to the most recent line of therapy, or with PD within 24 mo of initiation of first-line immunochemotherapy was 54%, 32% and 28% with ZO and 50%, 40% and 32% with O, respectively. The study met its primary endpoint: ORR was 68.3% with ZO vs 45.8% with O ( p= 0.0017). CRR was 37.2% (ZO) vs 19.4% (O); 18-mo DOR rate was 70.9% (ZO) vs 54.6% (O); and median PFS was 27.4 mo (ZO) vs 11.2 mo (O; hazard ratio [HR], 0.51 [95% CI, 0.32-0.81], p= 0.0040). Median time to new anti-lymphoma therapy or crossover was not evaluable (NE; ZO) vs 12.1 mo (O; HR, 0.37 [95% CI, 0.23-0.60], p< 0.0001). ORR for 29 pts who crossed over to ZO was 24.1%. Median OS was NE; 18-mo OS probability was 85.4% (ZO) vs 72.6% (O). Most common any grade AEs in the ZO arm were thrombocytopenia (34.3%), neutropenia (27.3%), diarrhea (16.1%), fatigue (14.0%), constipation (13.3%), cough (11.9%), pyrexia (11.2%), and dyspnea (10.5%). Grade ≥3 AEs with incidence > 5% with ZO were neutropenia (22.4%) and thrombocytopenia (14.0%); incidence of atrial fibrillation was 0.7% and major bleeding was 1.4%. Incidence of treatment-emergent AEs leading to death was 5.6% (ZO) and 9.9% (O). Conclusions: ZO demonstrated superior efficacy to O in treatment of pts with R/R FL. ZO had a favorable benefit-risk profile and represents a potential combination therapy for pts with R/R FL. Clinical trial information: NCT03332017.

Patients recently treated for B-lymphoid malignancies show increased risk of severe COVID-19: a CCC19 registry analysis

Patients with B-lymphoid malignancies have been consistently identified as a population at high risk of severe COVID-19. Whether this is exclusively due to cancer-related deficits in humoral and cellular immunity, or whether risk of severe COVID-19 is increased by anti-cancer therapy, is uncertain. Using data derived from the COVID-19 and Cancer Consortium (CCC19), we show that patients treated for B-lymphoid malignancies have an increased risk of severe COVID-19 compared to control populations of patients with non-B-lymphoid hematologic malignancies. Among patients with B-lymphoid malignancies, those who received anti-cancer therapy within 12 months of COVID-19 diagnosis experienced increased COVID-19 severity compared to patients with B-lymphoid malignancies off therapy, after adjustment for cancer status and several other prognostic factors. Our findings suggest that patients recently treated for a B-lymphoid malignancy are at uniquely high risk for severe COVID-19.

Outcomes in patients with aggressive B-cell non-Hodgkin lymphoma after intensive frontline treatment failure

BACKGROUND

Salvage immunochemotherapy followed by high-dose chemotherapy and autologous stem cell transplantation is the standard-of-care second-line treatment for patients with relapsed/refractory diffuse large B-cell lymphoma after first-line R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone). Outcomes after receipt of second-line immunochemotherapy in patients with aggressive B-cell lymphomas who relapse or are refractory to intensive first-line immunochemotherapy regimens (etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin, and rituximab [R-EPOCH], rituximab, hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone alternating with methotrexate and cytarabine [R-HyperCVAD], rituximab, cyclophosphamide, vincristine, doxorubicin, and high-dose methotrexate alternating with ifosfamide, etoposide, and cytarabine [R-CODOX-M/IVAC]) remain unknown.

METHODS

Outcomes of patients with non-Burkitt, aggressive B-cell lymphomas and relapsed/refractory disease after first-line treatment with intensive immunochemotherapy regimens who received platinum-based second-line immunochemotherapy were reviewed retrospectively. Analyses were performed to determine progression-free survival (PFS) and overall survival (OS) from the time of receipt of second-line immunochemotherapy.

RESULTS

In total, 195 patients from 19 academic centers were included in the study. The overall response rate to second-line immunochemotherapy was 44%, with a median PFS of 3 months and a median OS of 8 months. Patients with early treatment failure (primary refractory or relapse <12 months from completion of first-line therapy) experienced inferior median PFS (2.8 vs 23 months; P < .001) and OS (6 months vs not reached; P < .001) compared with patients with late treatment failure. Although the 17% of patients with early failure who achieved a complete response to second-line immunochemotherapy experienced prolonged survival, this outcome could not be predicted by clinicopathologic features at the start of second-line immunochemotherapy.

CONCLUSIONS

Patients with early treatment failure after intensive first-line immunochemotherapy experience poor outcomes after receiving standard second-line immunochemotherapy. The use of standard-of-care or experimental therapies currently available in the third-line setting and beyond should be investigated in the second-line setting for these patients.

Managing cytokine release syndrome (CRS) and neurotoxicity with step-fractionated dosing of mosunetuzumab in relapsed/refractory (R/R) B-cell non-Hodgkin lymphoma (NHL)

7518

Background: T-cell directed therapies (e.g., CAR-T, blinatumomab) are associated with significant risk of Grade (Gr) ≥3 neurotoxicity and CRS/infusion-related reaction (IRR). Mosunetuzumab is a CD20/CD3 bispecific antibody that directs T-cells to engage and eliminate malignant B-cells. We report safety results from an ongoing phase 1/1b study of mosunetuzumab in patients (pts) with R/R B-cell NHL. Methods: Pts received ascending doses on Day 1, Day 8, and Day 15 of Cycle 1 (step-fractionation), then a fixed dose on Day 1 of every 21-day cycle thereafter, up to a maximum of 17 cycles. Primary outcome measures included safety and efficacy. Results: As of October 23, 2018, 114 pts who received step-fractionated dosing of mosunetuzumab were evaluable for safety (Table). The majority of adverse events (AE) occurred during Cycle 1 and 2. Neurologic AEs (NAE), defined from Nervous System or Psychiatric System Organ Classes, were mostly low grade, transient (median duration 4 days) and reversible; most common ones were headache (14%) and dizziness (8%). Gr ≥3 NAEs occurred in 4 pts (4%) with only 1 treatment-related event (hepatic encephalopathy). CRS/IRR was reported in 25% of pts, with only 1 Gr 3 event. Most common CRS symptoms were pyrexia (86%), chills (38%), and tachycardia and headache (14% each). There were no Gr 5 events related to CRS or NAEs. No apparent dose toxicity relationship was observed with step-fractionation in these pts, despite escalation of the Cycle 1 Day 15 dose to 20 mg, consistent with observed peak IL-6 levels after a low Cycle 1 Day 1 dose. In these pts, objective responses were observed in 24/73 (33%; complete response [CR], 13 [18%]) aggressive NHL and 17/32 (53%; CR, 10 [31%]) indolent NHL pts. Conclusions: Step-fractionation has enabled continued dose escalation of mosunetuzumab with no apparent increases in toxicity, exhibiting a promising risk-benefit profile. Clinical trial information: NCT02500407; GO29781. [Table: see text]

Molecular monitoring of therapeutic milestones and clinical outcomes in patients with chronic myeloid leukemia

BACKGROUND

In the current study, the authors determined whether adhering to molecular monitoring guidelines in patients with chronic myeloid leukemia (CML) is associated with major molecular response (MMR) and assessed barriers to adherent monitoring.

METHODS

Newly treated patients with CML from the Quebec province-wide CML registry from 2005 to 2016 were included. Timely polymerase chain reaction (tPCR) was defined as the molecular assessment of BCR-ABL1 at the 3-month, 12-month, and 18-month time points from the initiation of tyrosine kinase inhibitor (TKI) therapy. The cohort was analyzed as a nested case-control study. Cases with a first-ever MMR (BCR-ABL1 ≤0.1%, assessed at any time during follow-up) were matched to up to 5 controls by duration of TKI therapy, volume of patients with CML at the treatment center, year of cohort entry, and age. Odds ratios (ORs) for the performance of tPCR and MMR were adjusted for sex, comorbidities, type of TKI, and other important covariates.

RESULTS

The cohort included 496 patients. Of 392 MMR events, 67.9% occurred before 18 months. The performance of tPCR was associated with a doubling of the MMR rate (OR, 2.23; 95% confidence interval [95% CI], 1.56-3.21) and was similar with 1 to 3 tPCRs performed (P = .67). Furthermore, tPCRs at 3 months (OR, 2.77; 95% CI, 1.81-4.23) and 12 months (OR, 3.00; 95% CI, 1.64-5.49) were associated with achieving early MMR, whereas tPCRs at 18 months were not (OR, 1.23; 95% CI, 0.80-1.89). Low-volume centers were found to have lower adherence to tPCR (OR, 0.60; 95% CI, 0.40-0.89).

CONCLUSIONS

Timely molecular assessment at 3 months and 12 months appears to benefit patients with CML. Adherence to timely monitoring should be encouraged, especially in low-volume treatment centers.

DYNAMO: A Phase II Study of Duvelisib (IPI-145) in Patients With Refractory Indolent Non-Hodgkin Lymphoma

PURPOSE

Indolent non-Hodgkin lymphoma (iNHL) remains largely incurable and often requires multiple lines of treatment after becoming refractory to standard therapies. Duvelisib was approved by the Food and Drug Administration for relapsed or refractory (RR) chronic lymphocytic leukemia or small lymphocytic lymphoma (SLL) and RR follicular lymphoma (FL) after two or more prior systemic therapies. On the basis of the activity of duvelisib, a first-in-class oral dual inhibitor of phosphoinositide 3-kinase-δ,-γ, in RR iNHL in a phase I study, the safety and efficacy of duvelisib monotherapy was evaluated in iNHL refractory to rituximab and either chemotherapy or radioimmunotherapy.

PATIENTS AND METHODS

Eligible patients had measurable iNHL (FL, SLL, or marginal zone B-cell lymphoma) double refractory to rituximab (monotherapy or in combination) and to either chemotherapy or radioimmunotherapy. All were treated with duvelisib 25 mg orally twice daily in 28-day cycles until progression, unacceptable toxicity, or death. The primary end point was overall response rate (ORR) using the revised International Working Group criteria for malignant lymphoma.

RESULTS

This open-label, global phase II trial enrolled 129 patients (median age, 65 years; median of three prior lines of therapy) with an ORR of 47.3% (SLL, 67.9%; FL, 42.2%; MZL, 38.9%). The estimated median duration of response was 10 months, and the estimated median progression-free survival was 9.5 months. The most frequent any-grade treatment-emergent adverse events (TEAEs) were diarrhea (48.8%), nausea (29.5%), neutropenia (28.7%), fatigue (27.9%), and cough (27.1%). Among the 88.4% of patients with at least one grade 3 or greater TEAE, the most common TEAEs were neutropenia (24.8%), diarrhea (14.7%), anemia (14.7%), and thrombocytopenia (11.6%).

CONCLUSION

In the DYNAMO study, oral duvelisib monotherapy demonstrated clinically meaningful activity and a manageable safety profile in heavily pretreated, double-refractory iNHL, consistent with previous observations. Duvelisib may provide a new oral treatment option for this patient population of which many are elderly and in need of additional therapies.

Phase II study of copanlisib, a PI3K inhibitor, in relapsed or refractory, indolent or aggressive lymphoma

Background

Copanlisib is a pan-class I phosphatidylinositol 3-kinase inhibitor with predominant activity against the α- and δ-isoforms.

Patients and methods

This phase II study evaluated the response rate of copanlisib administered intravenously on days 1, 8, and 15 of a 28-day cycle, in patients with indolent or aggressive malignant lymphoma. Archival tumor tissues were used for immunohistochemistry, gene-expression profiling, and mutation analysis.

Results

Thirty-three patients with indolent lymphoma and 51 with aggressive lymphoma received copanlisib. Follicular lymphoma (48.5%) and peripheral T-cell lymphoma (33.3%) were the most common histologic subtypes. Most patients (78.6%) had received prior rituximab and 54.8% were rituximab-refractory. Median duration of treatment was 23 and 8 weeks in the indolent and aggressive cohorts, respectively (overall range 2-138). Eighty patients were evaluated for efficacy. The objective response rate was 43.7% (14/32) in the indolent cohort and 27.1% (13/48) in the aggressive cohort; median progression-free survival was 294 days (range 0-874) and 70 days (range 0-897), respectively; median duration of response was 390 days (range 0-825) and 166 days (range 0-786), respectively. Common adverse events included hyperglycemia (57.1%; grade ≥3, 23.8%), hypertension (54.8%; grade ≥3, 40.5%), and diarrhea (40.5%; grade ≥3, 4.8%), all generally manageable. Neutropenia occurred in 28.6% of patients (grade 4, 11.9%). Molecular analyses showed enhanced antitumor activity in tumors with upregulated phosphatidylinositol 3-kinase pathway gene expression.

Conclusion

Intravenous copanlisib demonstrated promising efficacy and manageable toxicity in heavily pretreated patients with various subtypes of indolent and aggressive malignant lymphoma. Subtype-specific studies of copanlisib in patients with follicular, peripheral T-cell, and mantle cell lymphomas are ongoing. This trial is registered with ClinicalTrials.gov number NCT01660451 (Part A).

Metabolomic Profiling Reveals Cellular Reprogramming of B-Cell Lymphoma by a Lysine Deacetylase Inhibitor through the Choline Pathway

Despite the proven clinical antineoplastic activity of histone deacetylase inhibitors (HDACI), their effect has been reported to be lower than expected in B-cell lymphomas. Traditionally considered as “epigenetic drugs”, HDACI modify the acetylation status of an extensive proteome, acting as general lysine deacetylase inhibitors (KDACI), and thus potentially impacting various branches of cellular metabolism. Here, we demonstrate through metabolomic profiling of patient plasma and cell lines that the KDACI panobinostat alters lipid metabolism and downstream survival signaling in diffuse large B-cell lymphomas (DLBCL). Specifically, panobinostat induces metabolic adaptations resulting in newly acquired dependency on the choline pathway and activation of PI3K signaling. This metabolic reprogramming decreased the antineoplastic effect of panobinostat. Conversely, inhibition of these metabolic adaptations resulted in superior anti-lymphoma effect as demonstrated by the combination of panobinostat with a choline pathway inhibitor. In conclusion, our study demonstrates the power of metabolomics in identifying unknown effects of KDACI, and emphasizes the need for a better understanding of these drugs in order to achieve successful clinical implementation.

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Lysine deacetylase inhibitor (KDACI) treatment alters choline metabolism in B-cell lymphoma patients.

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KDACI-treated lymphoma cells acquire PI3K pathway dependency via increased choline kinase A (CHKA) activity.

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Targeting the acquired choline dependency improves the anti-lymphoma effect of KDACI.

Pera et al. explored the effects of the lysine deacetylase inhibitor panobinostat in the metabolism of patients with lymphoma. They demonstrated that panobinostat alters choline metabolism leading to PI3K pathway activation. Their findings revealed the mechanism behind the anti-lymphoma activity of dual lysine deacetylase/PI3K inhibitors, and uncovered a novel therapeutic strategy based on targeting choline pathway following panobinostat treatment.

Integration of end-of-life care in clinical trials for advanced malignancies

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Background: ASCO endorses early integration of palliative care in the treatment of patients with advanced cancers and encourages patient education with regards to prognosis and participation in medical decision making. We implemented a uniform process of discussing end of life and advance directives (AD) early in the course of experimental cancer treatment and assessed whether this process is aligned with our patients' perspectives. Methods: This was a pilot study in a research unit conducting early-phase trials for patients with no remaining standard of care. Accrual goal was 15 patients in four months. We identified patients with advanced malignancies who were screened for cancer trials and approached their physicians with a request to fill out an AD form in discussion with their patients. Upon initiation of treatment, we filled out a supportive care checklist for each patient. The patients filled out a structured questionnaire probing their views on end-of-life discussion and awareness to supportive care resources on cycle 2 day 1 (Q1) and on cycle 3 day 1 (Q2). Results: Out of 41 screened, we completed checklists for 36 patients. Of these, 26 filled out Q1 and 11 filled out Q1 + Q2. Response rate to the questionnaires was 100%. The patients were diagnosed with metastatic solid tumor (23) and hematologic malignancies (3) and had 2 (0-5) previous lines of treatment. Females and males were 14 and 12, respectively. AD forms were filled out in most patients (81%), but about half (54%) reported having had AD discussions with their physicians. Most patients (73%) were aware of supportive resources (palliative care, social worker, support groups), and most (62%) actually used them while on study. Agreement in Q1 and Q2 was comparable (Table), with some rise in agreement with the timing of AD discussion. Conclusions: In the context of treatment on clinical trials, a large-scale initiative is feasible. More patients agree with time that early discussion of AD meets their goals while almost half report having had no such discussion with their physicians. [Table: see text]

Results of a phase II trial of efficacy and safety of entospletinib (ENTO) in patients with lymphoplasmacytoid lymphoma/Waldenstrom's macroglubulinemia (LPL/WM)

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Background: ENTO is an orally bioavailable, selective inhibitor of spleen tyrosine kinase (Syk, a mediator of B-cell receptor [BCR] signaling). Targeting the BCR-signaling pathway has been a focus in B-cell related hematological malignancies including LPL/WM. Methods: This reports the LPL cohort in a phase 2 trial that more broadly evaluated efficacy and safety of ENTO (800 mg BID) in patients with relapsed and refractory (R/R) B-cell malignancies. Tumor response was assessed at weeks 8, 16, 24, and then every 12 weeks. The primary endpoint was PFS at week 24. Results: 17 LPL patients (median age 72 years [range: 47–89], 65% male, and median of 3 prior regimens [range: 1–8]) were enrolled. Prior therapies included anti-CD20 antibodies (100%), alkylating agents (71%; bendamustine 24%), purine analogues (24%), and vinca alkaloid (41%). No patient had prior ibrutinib. Median treatment duration was 16 weeks (range: 1-84), with 3 patients continuing on treatment. The most common treatment-emergent AEs (any grade/≥grade 3, independent of causality) were fatigue (53%, 6%), constipation (47%, 0%), nausea (47%, 6%), diarrhea (29%, 6%), insomnia (29%, 0%) and lab abnormalities including neutropenia (53%, 12%), increased creatinine (53%, 0%), increased ALT (41%, 6%) and decreased WBC (41%, 6%). One death due to progressive disease (PD) was reported within 30 days from last dose. 12 (71%) patients were evaluable for tumor response. 5 patients (29%) discontinued prior to initial tumor assessment: PD (n = 2), withdrawal consent (n = 2) and AE (n = 1). ORR was 24% (90% CI: 9%, 46%), with 1 (6%) patient achieving PR, 3 with minor response (18%) and 7 (41%) maintaining stable disease. Reductions of IgM from baseline were greatest in the patient with PR. PFS rate at week 24 was 82% (95% CI: 44%, 95%). Median time to treatment failure and median time to response were 3.7m and 1.9 m respectively. Median duration of response has not been reached. Conclusions: ENTO was well tolerated and demonstrated limited activity in patients with R/R LPL. Further development of ENTO in LPL will focus on its role in combination therapies. Clinical trial information: NCT01799889.

A phase 2 study of mocetinostat, a histone deacetylase inhibitor, in relapsed or refractory lymphoma

Deregulation of histone deacetylase (HDAC) is important in the pathogenesis of follicular lymphoma (FL) and diffuse large B-cell lymphoma (DLBCL). Mocetinostat, an isotype-selective HDAC inhibitor, induces accumulation of acetylated histones, cell cycle arrest and apoptosis in several cancers. This phase 2 study evaluated mocetinostat in patients with relapsed/refractory (R/R) DLBCL and FL. Seventy-two patients received mocetinostat (starting doses: 70-110 mg TIW, 4-week cycles). The best overall response rate (95% CI) was 18·9% (7·2, 32·2) for the DLBCL cohort (n = 41), and 11·5% (1·7, 20·7) for the FL cohort (n = 31). Responses were durable (≥90 days in 7 of 10 responses). Overall, 54·1% and 73·1% of patients derived clinical benefit (response or stable disease) from mocetinostat in the DLBCL and FL cohorts, respectively. Progression-free survival ranged from 1·8 to 22·8 months and 11·8 to 26·3 months in responders with DLBCL and FL, respectively. The most frequent treatment-related adverse events were fatigue (75·0%), nausea (69·4%) and diarrhoea (61·1%). Although mocetinostat had limited single-agent activity in R/R DLBCL and FL, patients with clinical benefit had long-term disease control. The safety profile was acceptable. This drug class warrants further investigation, including identifying patients more likely to respond to this agent, or in combination with other agents.

Methods for sample acquisition and processing of serial blood and tumor biopsies for multicenter diffuse large B-cell lymphoma clinical trials

Increasingly, targeted therapies are being developed to treat malignancies. To define targets, determine mechanisms of response and resistance, and develop biomarkers for the successful investigation of novel therapeutics, high-quality tumor biospecimens are critical. We have developed standard operating procedures (SOPs) to acquire and process serial blood and tumor biopsies from patients with diffuse large B-cell lymphoma enrolled in multicenter clinical trials. These SOPs allow for collection and processing of materials suitable for multiple downstream applications, including immunohistochemistry, cDNA microarrays, exome sequencing, and metabolomics. By standardizing these methods, we control preanalytic variables that ensure high reproducibility of results and facilitate the integration of datasets from such trials. This will facilitate translational research, better treatment selection, and more rapid and efficient development of new drugs. See all the articles in this CEBP Focus section, "Biomarkers, Biospecimens, and New Technologies in Molecular Epidemiology."

Phase 1 dose-escalation study of IV ixazomib, an investigational proteasome inhibitor, in patients with relapsed/refractory lymphoma

Ixazomib is an investigational proteasome inhibitor that has shown preclinical activity in lymphoma models. This phase 1 study assessed the safety, tolerability, maximum tolerated dose (MTD), pharmacokinetics, pharmacodynamics and preliminary activity of intravenous (IV) ixazomib in relapsed/refractory lymphoma patients who had received ⩾2 prior therapies. Thirty patients with a range of histologies received ixazomib 0.125−3.11 mg/m² on days 1, 8 and 15 of 28-day cycles. Patients received a median of two cycles (range 1−36). MTD was determined to be 2.34 mg/m². Most common drug-related adverse events (AEs) included fatigue (43%), diarrhea (33%), nausea, vomiting and thrombocytopenia (each 27%). Drug-related grade ⩾3 AEs included neutropenia (20%), thrombocytopenia (13%) and diarrhea (10%). Drug-related peripheral neuropathy occurred in four (13%) patients; no grade ⩾3 events were reported. Plasma exposure increased dose proportionally from 0.5−3.11 mg/m²; terminal half-life was 4−12 days after multiple dosing. Of 26 evaluable patients, five achieved responses: 4/11 follicular lymphoma patients (one complete and three partial responses) and 1/4 peripheral T-cell lymphoma patients (partial response). Sustained responses were observed with ⩾32 cycles of treatment in two heavily pretreated follicular lymphoma patients. Results suggest weekly IV ixazomib is generally well tolerated and may be clinically active in relapsed/refractory lymphoma.

Abstract 5538: Development of HDACi resistance in DLBCL leads to a switch in subtype towards a more differentiated B-cell and is associated with increased sensitivity to proteasome inhibition

Diffuse Large B Cell Lymhoma (DLBCL) is a highly heterogeneous disease in terms of clinical presentation, cell morphology, molecular characteristics and response to therapy. Gene expression profiling studies in patients have indicated that DLBCL can be sub-classified in relationship to the different stages of normal B cell development at which the cancer arises; germinal center B cell (GCB) and activated B cell (ABC). More recently, a similar approach distinguished three different reproducible clusters referred to as oxidative phosphorylation (OxPhos), B cell receptor/proliferation (BCR) and host response (HR). Importantly, DLBCL has also been well characterized at the genomic level. A large number of genes encoding epigenetic modifying enzymes are mutated in DLBCL, which implicates epigenetic regulation as an important factor in DLBCL pathogenesis, and a potential target for therapy. Among epigenetic therapies, histone deacetylase inhibitors (HDACi) have shown some clinical activity in DLBCL patients ranging from 5 to 25%, although responsive patients ultimately develop resistance.

Aiming to understand resistance and response to HDACi in DLBCL, we developed HDACi-resistant cell lines from the GCB and BCR subtype cells SUDHL6 and SUDHL4. Gene expression array analysis was performed in parental SUDHL6 and the resistant clone SUDHL6-X. Strikingly, we found that the resistant cells have switched gene expression profile from GCB to ABC subtype and from BCR to OXPHOS. Also, we observe features of more differentiated, plasmablast-like cells in SUDHL6-X cells and in all other resistant subclones we developed, including inactivated B cell receptor signaling, increased endoplasmic reticulum stress and activation of the unfolded protein response. These characteristics are reflected in a distinctive response pattern to other targeted drugs. We observe that HDACi-resistant cells become cross-resistant to the anti-CD20 antibody rituximab, but, interestingly, they gain susceptibility to inhibitors of the proteasome bortezomib and MLN2238. Importantly, analysis of lymphoma cells isolated from de novo resistant DLBCL patients treated with the HDACi panobinostat for 15 days showed a switch in gene expression profiles from GCB to ABC, similar to SUDHL6X cells, indicating that our observations are not exclusive of in vitro systems. In conclusion, we have shown for the first time that resistance to HDACi is associated with differentiation of lymphoma cells that we predict makes them insensitive to drugs targeting the B cell receptor and anti-CD20 antibody, but sensitive to proteasome inhibition.

Citation Format: Daphné Dupéré-Richer, Mena Kinal, Filippa Pettersson, Mona Hassawi, Yang ShaoNing, Torsten H. Nielsen, Kathleen Klein, Teresa Ezponda-Itoiz, Jonathan D. Licht, Nathalie Johnson, Sarit E. Assouline, Leandro Cerchietti, Wilson H. Miller, Koren K. Mann. Development of HDACi resistance in DLBCL leads to a switch in subtype towards a more differentiated B-cell and is associated with increased sensitivity to proteasome inhibition. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5538. doi:10.1158/1538-7445.AM2014-5538

Telomerase contributes to fludarabine resistance in primary human leukemic lymphocytes

We report that Imetelstat, a telomerase inhibitor that binds to the RNA component of telomerase (hTR), can sensitize primary CLL lymphocytes to fludarabine in vitro. This effect was observed in lymphocytes from clinically resistant cases and with cytogenetic abnormalities associated with bad prognosis. Imetelstat mediated-sensitization to fludarabine was not associated with telomerase activity, but with the basal expression of Ku80. Since both Imetelstat and Ku80 bind hTR, we assessed 1) if Ku80 and Imetelstat alter each other's binding to hTR in vitro and 2) the effect of an oligonucleotide complementary to the Ku binding site in hTR (Ku oligo) on the survival of primary CLL lymphocytes exposed to fludarabine. We show that Imetelstat interferes with the binding of Ku70/80 (Ku) to hTR and that the Ku oligo can sensitize CLL lymphocytes to FLU. Our results suggest that Ku binding to hTR may contribute to fludarabine resistance in CLL lmphocytes. This is the first report highlighting the potentially broad effectiveness of Imetelstat in CLL, and the potential biological and clinical implications of a functional interaction between Ku and hTR in primary human cancer cells.

Barriers to enrollment of patients with recurrent diffuse large B-cell lymphoma (DLBCL) in clinical trials

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Background: Research into novel therapies for relapsed/refractory DLBCL may be hindered by the perception these patients are difficult to capture in clinical trials. We performed a retrospective analysis of all DLBCL at our institution from 01/2006 to 03/2012 to identify hurdles to trial enrolment. Methods: All DLBCL cases were identified through the hospital tumor registry. Patients were included in the analysis if they had any diagnosis of DLBCL relapsed or refractory to standard therapy. Baseline demographic and clinical characteristics, details of treatment, responses, relapse, evaluation for clinical trials and participation in clinical trials were determined by review of hospital charts. Results: Of a total of 284 patients, 76 had relapsed/refractory disease, 10 of 20 had a successful ASCT, and there is insufficient data on 1 patient. Of the remaining 65, 11 (17%) made it to trial. The median age was 65, 34 were male, median number of prior therapies was 2, 74% had at least one comorbidity and 46% had at least 2, 62% of patients had de novo DLBCL, 18% transformed and 20% composite. 81% of cases were discussed at tumor board. Reasons for failing to enroll on trial included prohibitive comorbidity (21%), rapid progression (15%), decision for palliation (15%), prior second malignancy (9%), thrombocytopenia (13%), CNS disease (9%), proximity to ASCT (2%), no protocol for DLBCL (6%), palliative radiation (6%). Conclusions: We demonstrate that 17% of patients with DLBCL not responding to standard therapy make it to trial, the remainder does not mainly beacause of comorbidity and rapid progression. Similar barriers were found for solid tumor patients (Lara, JCO 2001) and a similar accrual rate was seen in relapsed non-small cell lung cancer (Baggstrom,J Thor Oncol 2011) . Relapsed DLBCL is a population for whom clinical trial research is challenging but possible.

A phase II study of single agent mocetinostat, an oral isotype-selective histone deacetylase (HDAC) inhibitor, in patients with diffuse large cell B-cell (DLBCL) and follicular (FL) lymphomas

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Background: Mocetinostat (MGCD0103) is an orally available, isotype-selective, non-hydroxamate HDAC inhibitor targeting HDACs 1,2, 3 and 11 with single-agent activity in Hodgkin’s lymphoma and in AML and MDS (in combination with 5-azacitidine). More than 430 patients have been treated to date. Methods: This open-label, phase II trial enrolled patients with DLBCL and FL. Patients received mocetinostat at doses ranging from 70-110 mg 3x/wk every 28 days. Anticancer activity, safety, pharmacokinetics and pharmacodynamics were evaluated. Results: Sixty-nine patients with DLBCL (n=41) and FL (n=28) were enrolled for treatment at starting doses of 85-110 mg. Median age was 62 years (range: 32 to 81). Median duration of treatment was ~3 months (range: <1 to 24). Objective response rate in DLBCL and FL, respectively, was 7/41 (17%; including 2 unconfirmed PRs) and 3/28 (11%; including 1 CR). Median time to response was 2.0 mos (range 1.7-21.0) and 5.3 mos (range 4.3-6.0) respectively. Stable disease was achieved by 13/41 (32%) and 14/28 (50%), respectively, for a disease control rate of 49% and 61%, respectively. Mean duration of SD in patients with DBLCL was ~4.5 mos (range 2-12 mos), with 10 patients remaining stable for ≥3 mos. Among FL patients, mean duration of SD was approximately 4.1 mos (range 1.7-13 mos), with 9 patients remaining stable for ≥3 mos. The FL CR occurred in a 62-year-old female with paratracheal, subcarinal and portal target lesions who achieved a PR after 4 cycles and CR after 12 cycles that persisted through the remaining 4 mos on study. Study drug was discontinued for adverse events in 19/69 (28%). Fatigue, weight loss or anorexia were most common (n=4 each). A total of 26 drug-related SAEs were reported among 12 patients (17%; 1-6 events per pt). There were no drug related deaths. Enrollment is complete and final data will be presented. Conclusions: Single-agent mocetinostat has activity in DLBCL and FL. Fatigue, gastrointestinal, and cardiac symptoms are the most common adverse events resulting in discontinuation of dosing. Based on the acceptable tolerability and clinical activity further development is warranted. Clinical trial information: NCT00359086.

A phase I/II study of sorafenib in combination with low dose cytarabine in elderly patients with acute myeloid leukemia or high-risk myelodysplastic syndrome from the National Cancer Institute of Canada Clinical Trials Group: trial IND.186

Sorafenib is active in patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). The National Cancer Institute of Canada (NCIC) Clinical Trials Group initiated a phase I/II study of the combination of sorafenib with cytarabine in older patients with AML or high-risk MDS who were unsuitable for intensive chemotherapy. FLT3 mutational status was determined in all patients. Twenty-one patients were enrolled (four MDS, 17 AML) with a median age of 77 years. The recommended phase II dose (RP2D) was cytarabine 10 mg bid days 1-10 and sorafenib 600 mg/day days 2-28. Dose-limiting toxicities were fatigue, sepsis and skin rash. Of 15 evaluable patients treated at the RP2D, two patients responded. The overall response rate for eligible patients was 10%. FLT3 mutations were found in only three patients. We conclude that this combination of sorafenib and cytarabine has limited activity in this unselected cohort of elderly patients with AML/MDS in which FLT3 mutations seemed underrepresented.

MLN9708, an investigational proteasome inhibitor, in patients (pts) with relapsed/refractory lymphoma: Emerging data from a phase I dose-escalation study

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Background: MLN9708 is a reversible, orally bioavailable, specific 20S proteasome inhibitor. This study (NCT00893464) studied the safety and determined the MTD of IV MLN9708 in pts with relapsed/refractory lymphoma, and characterized pharmacokinetics (PK) and pharmacodynamics (PD). Methods: Pts aged ≥18 yrs who had failed ≥2 chemotherapeutic regimens received IV MLN9708 on days 1, 8, and 15 of 28-day cycles until disease progression or unacceptable toxicity. One pt was enrolled at the 0.125 mg/m2 starting dose; dose doubling proceeded with 1 pt at each dose up to 1.0 mg/m2. Dose escalation occurred in ≤40% increments using a standard 3+3 scheme based on DLT occurrence in cycle 1. Blood samples were collected at multiple time points after dosing on days 1 and 15 of cycle 1 for PK/PD analyses. Results: At data cut-off (Dec 1 2011), 21 pts had been enrolled and treated: 1 each at 0.125, 0.25, 0.5 and 1 mg/m2, 4 at 1.4 mg/m2, 7 at 1.76 mg/m2, and 6 at 2.34 mg/m2. Median age was 57 yrs (range 23–78); 57% were male. Median number of prior therapies was 5; 29% had prior radiation, 24% prior stem cell transplant. Histologies included T-cell lymphoma (n=5), Hodgkin lymphoma (n=3), follicular lymphoma (n=2), DLBCL (n=1) and other indolent B-cell lymphoma (n=7). Pts had received a median of 2 cycles (range 1–22); 2 DLTs were seen (neutropenia at 1.76 and 2.34 mg/m2). All pts experienced drug-related AEs, including fatigue (48%), nausea (29%), diarrhea (29%), pyrexia, thrombocytopenia, and vomiting (each 24%). 43% had drug-related grade ≥3 AEs, 1 pt discontinued due to drug-related grade 3 neutropenia (2.34 mg/m2). Three pts had drug-related peripheral neuropathy (1 grade 1, 2 grade 2). There were no on-study deaths. Of 18 response-evaluable pts, 3 achieved PR (including 2 who remain in response and on-study for >1 yr) and 4 SD. PK analyses showed linear PK (0.5–2.34 mg/m2) and a terminal half-life of ~6–9 days. There was a dose-dependent increase in maximal whole blood 20S proteasome inhibition. Conclusions: These data suggest IV MLN9708 is generally well tolerated, with infrequent PN, and is clinically active in pretreated lymphoma pts. The trial is ongoing and updated data will be presented.

Predictive model for survival and toxicity in early-phase trials in hematology

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Background: Strict criteria are used to limit toxicity for patients (pts) enrolled in phase I/II clinical trials, but the ability to survive beyond 12 weeks, a common inclusion criterion, is subjective and error-prone. A prognostic score with 3 variables was designed and validated as an independent predictor of OS in pts with solid tumors included in phase I trials (Arkenau, JCO 2009). We examined the ability of objective measures to predict OS and risk of grade ≥3 toxicity in pts with hematologic malignancies enrolled in early-phase trials. Methods: A retrospective analysis was conducted on 290 pts in Phase I (79 pts) and II (211 pts) trials from the NCIC - Clinical Trials Group and our institution from 1995 to 2009. Only pts with survival data up to 90 days were included. Univariate model (UVA) was used to identify factors significantly associated with OS. A Cox proportional hazards model (MVA) included all factors identified from the UVA. Six prognostic factors were identified in the MVA, and each assigned a score of 0 or 1. Pts were categorized as high or low risk based on the total scores that they received, ≥3 were assigned to the high risk group, and a ≤2 to the low risk group. Kaplan-Meier method was used to generate the survival distribution for the high and low risk groups. Multivariate logistic regression was used to identify the risk factors for grade ≥3 toxicity. Results: The overall median survival was 238 days (95% CI 237 to 331), and 27% of pts had grade ≥ 3 toxicity. In the MVA, albumin (alb), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), lymphocytes, platelets (plts) and diagnosis were significantly associated with OS. Pts in the low risk group had a median survival of 10.6 months, relative to 2.4 months among pts in the high risk group. Survival at 90 days was 80% in lower risk vs. 36% in the high risk group. In addition, the MVA for toxicity showed that alb, ALP, LDH, plts and performance status were significantly associated with grade ≥3 toxicity. Conclusions: Our model predicts OS, 90 day survival and risk of grade ≥ 3 toxicity among pts with hematologic malignancies entered in Phase I/II trials. Future work will include a linear predictor score based on MVA to refine the prediction model. The model will also be validated using another dataset.