Conte, Michael

Abstract Backgrounds B cell receptor (BCR) signals and microenvironment protection have been recognized to have key influences on CLL survival and activation. Akt activation is down-stream of the BCR signaling cascade and is critical in the mediation of the bi-directional interactions between CLL B-cells and bone marrow stroma. MK2206 is an allosteric Akt inhibitor previously tested for safety in solid tumor patients. Our preclinical data has demonstrated the synergy of MK2206 with bendamustine (B) to induce CLL apoptosis in vitro. MK2206 also abolished the signal activation and cytokine production induced by BCR ligation in CLL leukemic cells (Ding, ASH 2012). Therefore, we conducted a phase 1 trial testing the safety and efficacy of MK2206 in combination with bendamustine and rituximab (BR) for patients with relapsed/refractory CLL. Methods A phase 1 dose-escalation study was designed to define the maximum tolerated dose (MTD) as well as the safety and efficacy of 3 dose levels (90 mg or 135 mg or 200 mg weekly) of the oral Akt inhibitor MK2206 in combination with bendamustine (70 mg/m2 daily for 2 days in each cycle) and rituximab (cycle 1: 375 mg/m2, cycle 2-6: 500 mg/m2) therapy in relapse/refractory CLL patients. To test the targeting efficacy of MK2206 on Akt and downstream signals, we designed a one-week “run-in” of single agent MK2206 before the initiation of BR during cycle 1. MK2206 was then given along with BR on day 1 of cycles 2-6. Tumor response was evaluated 2 months after the 6th/last cycle of therapy based on IWCLL 2008 criteria. Correlative laboratory studies included assessment of Akt signaling and the plasma cytokine levels (multiplex beads assay (Invitrogen)) at baseline and after one week of first dose of single agent MK2206. Results Nine patients (median age 68) were enrolled in the phase I portion of this trial. All 9 patients had unmutated immunoglobulin heavy chain variable region genes (IGHV) and 4 had del(11q). Six had received prior chemoimmunotherapy (CIT: FCR or PCR or PCO) and 5 had high risk disease defined as early progression within 26 months of the last CIT. Three had received alemtuzumab containing regimen. We have observed potent lymphocyte mobilization in all evaluated patients (n=7) after one-dose of MK2206 during week 1 (mean increase ALC: 35%) as well as reductions of plasma CCL3, CCL4 and CCL2 in the majority of the patients. A single dose-limiting toxicity (DLT) (febrile neutropenia and hemolytic anemia) was observed at dose level 1 (90 mg weekly) among 6 patients treated at this dose. Two patients with dose-limiting toxicities at dose level 2 (135 mg weekly) were observed where one patient had a rash and one patient had dehydration and febrile neutropenia among three patients treated at this dose. Accordingly, the 90 mg once weekly dose was determined to be the MTD for phase 2 trial testing. The most frequent grade 3 or 4 adverse events observed to date were neutropenia (44%) including febrile neutropenia (22%), rash (22%), diarrhea (22%), nausea and vomiting (11%), dehydration (11%), hemolytic anemia (11%) and thrombocytopenia (11%). The frequency of cytopenias was similar to the published German experience with BR (50% grade 3 or 4 hematological toxicities compared to 44% in N1087) in relapsed CLL patients (Fischer, JCO 2011). The median number of cycles received was 6 (range 1-6). Using an intent to treat analysis, two patients achieved complete response (CR, n= 2, 22%), one patient achieved nodular partial response (nPR, n=1, 11%) and five patients achieved a partial response (PR, n=5, 56%). The overall response rate (ORR) is 89%. Conclusion The Akt inhibitor MK2206 in combination with BR is well tolerated in patients with relapsed/refractory CLL. Single dose of MK2206 inhibits Akt phosphorylation, mobilizes leukemic cells and decreases plasma cytokines involved in BCR signals. The preliminary efficacy of this combination demonstrated promising results with a 89% ORR and 22% CR albeit in the small phase 1 cohort. These results compare favorably to BR alone (9% CR and 59% ORR) in relapsed/refractory CLL patients. Phase 2 testing of this combination is now underway. Acknowledgment This work was supported by the funding from NCI grant K23CA160345 (WD), NCI grant CA95241 (NEK) and Alliance for Clinical Trials in Oncology (CA025224 and CA33601). Disclosures: Off Label Use: MK2206, used in a phase 1 trial of relapsed CLL disease. Shanafelt:Genentech: Research Funding; Glaxo-Smith-Kline: Research Funding; Cephalon: Research Funding; Hospira: Research Funding; Celgene: Research Funding; Polyphenon E International: Research Funding. Zent:Novartis: Research Funding; GlaxSmithKline: Research Funding; Biothera: Research Funding; Genzyme: Research Funding; Genentech : Research Funding. Reeder:Celgene: Research Funding; Novartis: Research Funding; Millenium: Research Funding.

Abstract Background: High risk CLL patients treated with novel targeted therapies continue to experience disease progression (PD), and more than 50% of these PD patients evolve into Richter's syndrome (RS), (Maddocks, Jama Oncol 2015). Standard chemotherapy for large cell lymphoma has limited efficacy (median overall survival <12 months) in RS. Novel immunotherapy using a PD-1 antibody to block immune checkpoint signals to activate the cytotoxic T -cell has significant efficacy in relapsed Hodgkin lymphoma (Ansell, NEJM 2015). We conducted a phase 2 trial to test the safety and clinical efficacy of the anti-PD-1 antibody pembrolizumab in patients with relapsed/refractory CLL and relapsed low grade B non-Hodgkin lymphoma (B-NHL) (MC1485 trial). Methods: MC1485includes two arms: patients with relapsed/refractory CLL (including RS) and patients with relapsed B-NHL. The main end points of this study are safety and overall response rate. The first 6 patients enrolled in either arm were included in a designed safety interim analysis. Here we report the initial interim analysis from the CLL arm. Relapsed/refractory CLL including RS who had ECOG performance 0-2 and normal organ function were included. Patients with active autoimmune disease or interstitial lung disease were excluded. Pembrolizumab 200 mg was administered intravenously every 3 weeks until progression, excessive toxicity, or completion of 2 years of therapy. Soluble plasma PD-L1 levels were measured in these 6 patients using an established ELISA assay (Frigola, Clin Cancer Res, 2011). CD8+ T cell subsets were assessed for their functional status using an established analysis (Liu, Oncoimmunology. 2013) at baseline and after 2 cycles of therapies. Results: As of July 27th, 2015, 16 relapsed/refractory CLL patients including 5 RS patients were enrolled. The median age was 71 years (58-81). The median number of prior therapies was 3 (1-6). All CLL patients had received chemoimmunotherapy (FCR/PCR). 4 out of 5 RS patients had received anthracycline-containing chemotherapy. 5 out of 8 patients who had received prior ibrutinib therapy progressed on ibrutinib. 8 patients had 17p-/TP53 mutation. Herein, we report preliminary results from the interim analysis of CLL arm including 4 RS and 2 CLL as well as the 5th RS who had response evaluation by PET. The median cycles of therapy administered was 4 (3-7). One patient experienced grade 2 cytokine release syndrome with transient febrile neutropenia, grade 3 headache and skin rashes. These symptoms resolved with steroid therapy. One patient experienced grade 3 myalgia and was also treated with steroids. The other patients in this safety cohort tolerated pembrolizumab well. The most common drug-related adverse events were grade 1 dyspnea (33%, 2/6) and grade 1 anemia (33%, 2/6). Based on investigator assessment using the Cheson 2007 International Working Group Criteria, 4 out of 5 RS patients had responded to therapy. One patient had a complete remission after 2 cycles and remains in remission. One patient had almost complete PET response after two cycles and is classified as PR as her bone marrow have not been re-evaluated yet. Two patients had notable responses with nodal and skin lymphoma improvements before they showed potential evidence of progressive diseases. The remaining 1 RS and 2 CLL had stable disease and continued on therapy at the last follow-up. Soluble PD-L1 levels (sPD-L1, n=6) were measured at baseline and after 2 cycles of therapies. 3 RS patients who had responded to therapy had decreased or stable sPD-L1 levels. The 4th RS and two CLL had increased sPD-L1 levels and had not demonstrated clinical response. CD8 T-cell subset analyses performed blindly (n=4) showed increased CD8 T cell function in one of the 4 patients tested. This patient who demonstrated CD8 T cell functional enhancement is the only patient in the 4 tested patients who had notable response to pembrolizumab. Conclusion: Pembrolizumab is tolerated in relapsed CLL and RS patients. Early efficacy observed in heavily pretreated RS patients including patients progressed on both anthracycline-based treatment and ibrutinib indicate PD-1 inhibition is a promising novel approach in patients with RS. Our CD8 T cell subset analysis may be used as a biomarker assay to predict clinical response in the era of novel immunotherapy. This trial and further correlative analysis is ongoing and will be presented at the ASH meeting. Disclosures Ding: Merek: Research Funding. Shanafelt:Cephalon: Research Funding; Pharmactckucs: Research Funding; Janssen: Research Funding; Hospira: Research Funding; Polyphenon E Int'l: Research Funding; Celgene: Research Funding; Glaxo-Smith_Kline: Research Funding; Genentech: Research Funding. Kay:Tolero Pharma: Research Funding; Hospira: Research Funding; Pharmacyclics: Research Funding; Genentech: Research Funding; Celgene Corporation: Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding. Ansell:Bristol-Myers Squibb: Research Funding; Celldex: Research Funding.

Abstract Introduction: Ibrutinib has shown remarkable safety and efficacy in CLL. Due to CYP3A4 (3A4) metabolism, the concurrent use of 3A4 inhibitors/inducers with ibrutinib should be avoided. Ibrutinib is also associated with bleeding complications, in part due to effects on collagen-mediated platelet aggregation, thus caution is advised with the simultaneous use of anticoagulant (AC) and antiplatelet agents. It is unknown what proportion of CLL patients starting ibrutinib therapy in routine practice are on these medications. We conducted a retrospective study to evaluate these aspects in a large cohort of CLL pts treated with ibrutinib outside the context of clinical trials. Methods: Following IRB approval, consecutive CLL pts who initiated ibrutinib off-protocol at Mayo Clinic, Rochester, MN from November 2013 through July 2015 were evaluated. A medication review for drug-drug interactions was performed by a pharmacist on all pts. Baseline characteristics, concomitant medications, and toxicity were recorded. Time to toxicity and ibrutinib discontinuation were analyzed by Kaplan Meier and cumulative incidence methods accounting for competing risk of death, respectively. Results: Ninety-six CLL pts started ibrutinib. Median age was 66 years and 64 (67%) were male. Ibrutinib indications included: relapsed/refractory CLL (n=84), treatment-naïve CLL with del17p (n=8), and CLL with Richter's transformation (n=4). Approximately 80% had unmutated IGHV and 45% had del17p or del11q on FISH. Upon initial pharmacy consult prior to ibrutinib, the median number of concomitant medications was 9 (range, 1-31). Sixty (63%) pts were taking concurrent medications increasing their risk of ibrutinib toxicity and 4 (4%) pts were on drugs potentially reducing ibrutinib efficacy. At ibrutinib initiation, 16 (17%) pts were on concomitant 3A4 inhibitors. This included 9 (9%) on moderate 3A4 inhibitors (fluconazole, diltiazem, imatinib, cyclosporine) and 7 (7%) on strong 3A4 inhibitors (voriconazole, posaconazole, clarithromycin, itraconazole). In 4 pts, the 3A4 inhibitor was switched to another agent or discontinued to allow standard 420 mg daily dosing. Ibrutinib was initiated at 140 mg daily in 7 pts on moderate 3A4 inhibitors and at 140 mg every 48 hours in 5 pts on strong 3A4 inhibitors. Four (4%) pts were on strong 3A4 inducers (carbamazepine, rifampin, rifabutin) at the initiation of ibrutinib. The 3A4 inducer was discontinued prior to ibrutinib start in 3 pts, while the initial ibrutinib dose was decreased to 140 mg every 48 hours in the remaining patient (also on 2 strong 3A4 inhibitors). During the course of ibrutinib, an additional 8 (8%) pts were started on 3A4 inhibitors/inducers which necessitated dose modifications. Upon commencing ibrutinib, 9 (9%) pts were on concomitant AC (6 warfarin, 3 enoxaparin). Due to significant bleeding risk, warfarin was switched to enoxaparin in 2 pts, to aspirin (ASA) in 1 and warfarin was discontinued in 1. In 2 pts, an alternative AC could not be used so ibrutinib was begun at 140 mg daily and titrated upward. Twenty-nine (30%) pts were on ASA (3 [3%] also on clopidogrel) at ibrutinib initiation. Nineteen (20%) pts were on selective serotonin release inhibitors (SSRIs), and 9 (9%) were on NSAIDs. Thirteen (13%) pts were on fish oil and 24 (25%) were on herbal medications; all of which were discontinued prior to starting ibrutinib. Ten (10%) pts had clinically significant bleeding on ibrutinib including 4 (4%) requiring hospitalization (1 subdural hematoma). Of these 4 pts, 1 was on enoxaparin, 2 were on a SSRI and 1 a NSAID. Six pts had minor bleeding necessitating a dose reduction of ibrutinib to 140-280 mg daily. After 16 months follow-up, the risk of bleeding was 21% (95% CI: 1-37%, Figure). After a median follow-up of 7.6 months, 73 (76%) pts remain on ibrutinib. There was no difference in rates of discontinuation of ibrutinib between patients who were on 3A4 inhibitors/inducers versus those who were not. Conclusion: In the "real-world" setting, 2 out of 3 CLL patients commencing ibrutinib therapy is on a concomitant medication with a potentially clinically significant drug-drug interaction with ibrutinib. These findings have implications for the practicing hematologist who must maintain a high degree of vigilance when prescribing ibrutinib to CLL pts. We highly recommend a formal medication review by a clinical pharmacist in all patients initiating ibrutinib. Figure 1. Figure 1. Disclosures Ding: Merck: Research Funding. Kay:Hospira: Research Funding; Tolero Pharma: Research Funding; Genentech: Research Funding; Celgene Corporation: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding. Shanafelt:Glaxo-Smith_Kline: Research Funding; Pharmactckucs: Research Funding; Celgene: Research Funding; Genentech: Research Funding; Cephalon: Research Funding; Janssen: Research Funding; Hospira: Research Funding; Polyphenon E Int'l: Research Funding.

Abstract Introduction: The Food and Drug Administration (FDA) approved ibrutinib in February 2014 based on results from a pivotal phase 2 clinical trial that enrolled 85 patients with relapsed/refractory CLL. A subsequent phase 3 trial confirmed the superior progression-free survival (PFS) and overall survival (OS) of ibrutinib compared to ofatumumab in 391 CLL patients. However, there is no information on the efficacy and safety of ibrutinib in CLL patients treated outside the context of clinical trials. Additionally, it is unclear if the reasons for discontinuation of ibrutinib differ in routine clinical practice from those described in patients treated on clinical trials. We conducted a retrospective study to evaluate these aspects in a large cohort of CLL patients treated with ibrutinib off-protocol. Methods: After IRB approval, CLL patients seen at Mayo Clinic, Rochester, MN, and treated with commercial ibrutinib from November 2013 through July 2015 were evaluated. The baseline characteristics, time to therapy discontinuation, reasons for discontinuation and survival following discontinuation were abstracted. Results: One hundred thirty-five patients with CLL were treated during the study interval; 124 received ibrutinib for relapsed/refractory CLL and 11 received ibrutinib for treatment-naïve CLL with TP53 disruption (either del17p on FISH or TP53 mutation). Patients with relapsed/refractory CLL (n=124) Patients were high-risk, with a median of 3 prior therapies (range, 1-15), 81% had unmutated IGHV, and 38% had either del11q or del17p on FISH testing. After a median follow-up of 6.4 months, 101 remain on ibrutinib therapy. The estimated proportion of patients continuing ibrutinib at 6 months was 84% (95% CI: 77-92%) and at 12 months was 70% (95% CI: 59-83%). Of the 23 who discontinued ibrutinib therapy, 8 discontinued for progressive disease (2 progressive CLL; 6 Richter's transformation). The remaining 15 discontinued therapy for reasons other than progression, including: infection (n=3), bleeding (n=3), diarrhea (n=1), atrial fibrillation (n=1), rash (n=1), immune thrombocytopenia (n=1), renal dysfunction (n=1), severe edema (n=1), MDS (n=1) and physician preference (n=2). Table 1 shows the reasons for discontinuation of ibrutinib in patients treated on clinical trials (Maddocks, JAMA Oncology, 2015) compared to the current cohort of patients. The estimated cumulative incidence of discontinuation of ibrutinib therapy due to CLL progression/Richter's transformation at 6 and 12 months was 9% (95% CI: 4-17%) and 12% (95% CI: 5-23%), respectively. The estimated cumulative incidence of ibrutinib discontinuation due to reasons other than progression at 6 and 12 months was 10% (95% CI: 5-17%) and 22% (12-34%), respectively (Figure). The median survival after discontinuation of ibrutinib for patients who had CLL progression was 3.5 months, not reached in patients who developed Richter's transformation and not reached in those patients who discontinued ibrutinib due to reasons other than progression. Patients with treatment-naïve CLL (n=11) All patients had evidence of TP53 disruption (9 had del17p, 3 had TP53 mutation, and 1 had both). After a median follow-up of 2.8 months, no patient has had progression of CLL, and 2 patients have discontinued ibrutinib therapy for reasons other than CLL progression (atrial fibrillation, n=2). The estimated proportion of patients continuing ibrutinib at 6-months was 71% (95% CI: 45-100%). All 11 are still alive, and no patient has undergone allogeneic stem cell transplantation. Conclusion: This is the first study that describes the outcomes of a large cohort of CLL patients treated with ibrutinib outside the context of clinical trials. Patients treated in routine practice appear more likely to discontinue ibrutinib for reasons other than progression of disease, compared to those participating in clinical trials. Our results confirm the poor survival of CLL patients who progress on ibrutinib. Table 1. Comparative analysis of reasons for discontinuation of ibrutinib in patients with relapsed/refractory CLL: Characteristic Current Study (%) Maddocks (JAMA Oncology 2015) (%) No. of patients 124 308 Median follow-up (months) 6.4 20 Reasons for Discontinuation Progression of disease CLL 2 (2) 13 (4) Richter's transformation 6 (5) 15 (5) Non-progression of disease Infection 3 (2) 28 (9) Other 12 (10) 17 (5) Figure 1. Figure 1. Disclosures Ding: Merek: Research Funding. Kay:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding; Hospira: Research Funding; Genentech: Research Funding; Pharmacyclics: Research Funding; Tolero Pharm: Research Funding. Shanafelt:Cephalon: Research Funding; Celgene: Research Funding; Glaxo-Smith_Kline: Research Funding; Polyphenon E Int'l: Research Funding; Hospira: Research Funding; Janssen: Research Funding; Pharmactckucs: Research Funding; Genentech: Research Funding.

Abstract Background: PRCA is characterized by severe normochromic normocytic anemia, reticulocytopenia, and markedly reduced bone marrow erythroid precursors with intact leukocytic and megakaryocytic lineages. There is limited information about the prevalence and outcomes of PRCA in CLL, with the vast majority of information derived from case reports and small series comprising <10 patients. Here, we describe the clinical features, therapy, and outcomes of CLL patients with PRCA seen at our institution. Methods: The Mayo Clinic CLL Database includes all patients with a diagnosis of CLL evaluated at Mayo Clinic Rochester, MN between January 1995 and December 2014. We identified patients diagnosed with PRCA per the following diagnostic criteria: those who presented with normocytic anemia, had decreased erythroid precursors on bone marrow examination, and reticulocytopenia that could not be explained by any other cause besides PRCA. The baseline demographics, clinical characteristics, therapy, and outcomes were abstracted from the electronic medical records. We generated descriptive statistics and calculated overall survival (OS) from diagnosis date (PRCA, autoimmune cytopenia [AID], or CLL) to last known alive or death date. OS was plotted using Kaplan Meier curves and compared between groups using log-rank statistic. The Mayo Clinic IRB approved this study. Results: Of the 3945 CLL patients seen during the study interval, we identified 30 patients who met the diagnostic criteria of PRCA as described in the Methods section. The baseline characteristics, etiology and therapy for PRCA are shown in Table 1. The median time to PRCA from CLL diagnosis was 4.5 years (range-0.1-14 years). Of the 13 patients with IGHV results available, 12 (92%) were IGHV unmutated. Twenty-one (70%) were male and their median age at PRCA diagnosis was 67 years (range 40-81 years). Parvovirus testing was positive in 6 of 24 (25%) patients who were tested; 3 of these patients were treated with IVIG, 2 were treated with prednisone and IVIg, and 1 was treated with prednisone and rituximab. Eight patients (27%) had both PRCA and autoimmune hemolytic anemia (AIHA), and 1 patient (3%) had concomitant PRCA and immune thrombocytopenia (ITP). Of the 27 patients for whom we have treatment data, 10 required only one treatment regimen and 17 required 2-6 treatment regimens, with two patients requiring splenectomy for concomitant AIHA. The median survival of CLL patients after a diagnosis of PRCA was 4.6 years (Figure 1). There was no difference in survival between PRCA cases with and without parvovirus (p=0.92). Compared to newly diagnosed CLL Rai stage III/IV patients, there was no difference in OS (p=0.53). There was no statistically significant difference in survival from an AID cytopenia diagnosis when comparing PRCA, ITP, AIHA, and Evans syndrome (Figure 1; median 5 years for PRCA and 6 years for other groups; p=0.17). Conclusion: PRCA is a rare complication in CLL, occurring in <1% CLL patients seen at our institution over the past 20 years. Parvovirus was the etiologic factor in ~25% of patients and did not influence outcomes. There appears to be no significant difference in outcomes of PRCA patients compared to patients with other AID in CLL. Table 1. Patient Characteristics Characteristic N [range] or (%) Number of patients 30 Males 21 (70) IGHV status* · Unmutated · Mutated 12 (92) 1 (8) FISH results at CLL diagnosis* · 17p- · 11q- · Trisomy 12 · 13q- · Negative 0 (0) 1 (10) 3 (30) 3 (30) 3 (30) At PRCA Diagnosis Median age 67 [40 - 81] Median hemoglobin (gm/dL)* [normal range 12-15.5 gm/dL] 8.2 [3.5 - 10.8] Median absolute reticulocyte count (x 109/L)* [normal range: 38 - 113 x 109/L] 3.5 [0.0 - 25.3] Patients treated for CLL prior to PRCA diagnosis 25 (83) Etiology of PRCA Parvovirus (n = 24) 6 (25) Therapy-related: · Fludarabine · Alemtuzumab/rituximab · Pentostatin/cyclophosphamide/rituximab 3 (10) 1 (3) 1 (3) Autoimmune (neither therapy nor parvovirus related) 19 (63) Initial Therapy of Non-Parvovirus Related PRCA Steroids alone 2 (8) Steroids and Rituximab 3 (13) Steroids in combination with: · IVIG, Chlorambucil · Cyclosporine · Rituximab, IVIg · IVIg, splenectomy 1 (4) 2 (8) 1 (4) 1 (4) Monoclonal Ab alone · Alemtuzumab · Rituximab 1 (4) 4 (17) Cyclosporine 1 (4) Cyclophosphamide 2 (8) RCP (Rituxan, Cyclophosphamide, and prednisone) 2 (8) IVIg 1 (4) Not available 3 (13) *Not available for all patients Figure 1. Figure 1. Disclosures Ding: Merck: Research Funding. Kay:Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Research Funding; Hospira: Research Funding; Tolero Pharma: Research Funding; Celgene Corporation: Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Research Funding. Shanafelt:Cephalon: Research Funding; Hospira: Research Funding; Glaxo-Smith-Kline: Research Funding; Genentech: Research Funding; Jannsen: Research Funding; Celgene: Research Funding; Polyphenon E International: Research Funding; Pharmacyclics: Research Funding.

Abstract Background Severe cytopenias in CLL are typically associated with bone marrow failure due to massive infiltration of the bone marrow by leukemic cells and negatively impact patient morbidity/mortality. Although near complete marrow replacement by CLL is typically observed in patients whose degree of cytopenia meet criteria for advanced Rai stage disease (Hg<11g/dL; platelet <100 x10^9/L), profound variability in the degree of cytopenia and the extent of marrow infiltration exists, and the relationship between these dimensions is not well characterized. Methods We used the Mayo Clinic CLL database to identify all previously untreated CLL/SLL patients who underwent bone marrow biopsies. CLL patients known to have autoimmune-based cytopenias were excluded from this study. Hemoglobin, platelets, absolute neutrophil count (ANC), absolute lymphocyte count (ALC), and absolute monocyte (AMC) at the time of bone marrow biopsy were collected. Characteristics from bone marrow biopsy including marrow cellularity, % CLL involvement, CLL leukemic index (calculated as % cellularity times % CLL), and non-CLL leukemic index (calculated as % cellularity times (1-% CLL)) were also collected. Bone marrow cellularity and % CLL involvement were recorded in the Mayo Clinic CLL database based on clinical estimates made by Mayo hematopathologists. Clinical characteristics and CLL prognostic factors (e.g., Rai stage, CLL FISH, IGHV, ZAP-70, CD38 and CD49d) were also obtained from the database. Age- and sex-adjusted Pearson correlations between the bone marrow measurements and hemoglobin and platelet levels were computed, and scatterplots were created. Results A total of 695 untreated CLL patients diagnosed between 1972 and 2015 who had a CBC test at the time of bone marrow biopsy performed at Mayo Clinic were identified. Median age at diagnosis was 61 years, and 487 (70%) patients were men. Mean time from CLL diagnosis to bone marrow biopsy was 2.2 years. At the time bone marrow biopsy was performed, 20% of patients had advanced stage disease (Rai III/IV) disease, while 44% and 36% had intermediate (Rai I/II) and early stage (Rai 0), respectively. With respect to prognostic parameters, 53% had unmutated IGHV and 20% had high risk CLL FISH (11q- and 17p-). The distribution of other prognostic factors included 43% CD49d+, 35% CD38+, and 42% ZAP-70+ CLL diseases. Median peripheral blood counts were: hemoglobin 13g/dL, platelet 167,000/mL, ALC 26,600/mL, ANC 4100/mL, AMC 700/mL. The median bone marrow cellularity and percent CLL involvement were 70% and 70%, respectively. The median CLL leukemic index was 42%, and median non-CLL leukemic index was 21%. Pearson correlation analysis of bone marrow measurements with peripheral blood hemoglobin found the strongest correlation with the CLL leukemic index (r= -0.49, p<0.001) (Figure), followed by the % marrow CLL involvement (r= -0.45, p<0.001), cellularity (r= -0.40, p<0.001), and non-CLL leukemic index (r= 0.37, p<0.001). Pearson correlation analysis of the bone marrow measurements with platelet count also found the strongest correlation with the CLL leukemic index (r= -0.39, p<0.001), followed by % marrow CLL involvement (r= -0.38, p<0.001), non-CLL leukemic index (r= 0.35, p<0.001), and cellularity (r= -0.28, p<0.001). The peripheral blood ANC levels did not correlate with the four bone marrow measurements. Age- and sex-adjusted Pearson correlations between the bone marrow measurements and hemoglobin and platelet levels were similar to the above unadjusted results. Conclusion To our knowledge, this is the first study to examine the relationship between peripheral blood counts and the extent of bone marrow infiltration in patients with CLL. Although the bone marrow leukemic index had the strongest correlation with peripheral blood Hg and platelet counts, the correlation was modest with an r value of -0.49. These findings suggest that the extent of infiltration of the bone marrow by CLL cells only partially explains of the anemia and thrombocytopenia observed in CLL, indicating other biologic interactions between CLL B-cells and hematopoietic cells contribute to anemia and thrombocytopenia in these patients. More research is needed to determine the nature of these interactions. Disclosures Ding: Merek: Research Funding. Kay:Genentech: Research Funding; Pharmacyclics: Research Funding; Hospira: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding; Tolero Pharm: Research Funding. Shanafelt:genentech: Research Funding; Glaxo-Smith-knine: Research Funding; Celgene: Research Funding; Cephalon: Research Funding; Pharmacyclics: Research Funding; Janssen: Research Funding; Hospira: Research Funding; Polyphenon E Int'l: Research Funding.

Abstract Patients with very-high risk (purine analogue refractory and TP53 defective) CLL have limited treatment options. In these patients alemtuzumab can be effective against CLL cells in the circulation and bone marrow, and in combination therapy with fludarabine can be active in patients with bulky disease, but these regimens have a high risk of serious infections. Addition of rituximab to alemtuzumab can also improve efficacy but has limited activity against bulky disease. We conducted a phase II clinical trial to determine the efficacy and toxicity of therapy with pentostatin, alemtuzumab, and low dose higher frequency rituximab (PAR) in patients with relapsed/refractory or progressive CLL with 17p13 deletion. The rituximab schedule was designed to decrease the loss of CD20 expression by circulating CLL cells. Methods This two-stage phase II trial study (NCT00669318) conducted at the Mayo Clinic Rochester and University of Iowa with IRB approval had an accrual goal of 38 evaluable patients. Eligibility required a diagnosis of progressive CLL by standard criteria and either previous treatment for CLL (<4 purine analogue regimens) or 17p13 deletion (17p13-). Exclusion criteria were organ failure, poor performance status (ECOG >3), infection with HIV, hepatitis B, hepatitis C, active autoimmune cytopenia, or alemtuzumab therapy within the past 2 months. Rituximab 20 mg/m2 IV M-W-F started on day 1, alemtuzumab started on day 3 with an escalation of 3-10-30 mg/d SQ and then 30 mg M-W-F from day 8, and pentostatin 2 mg/m2 IV every 2 weeks started on day 8. Peg-G-CSF or GM-CSF was used after each dose of pentostatin and patients received Pneumocystis and Varicella prophylaxis. CMV PCR assays were done weekly during treatment and viremia was treated with either valganciclovir or ganciclovir. Cycle 1 was 5 weeks and subsequent cycles were 4 weeks. At the end of cycle 2 patients with a clinical CR had a CT scan and a bone marrow study with immunohistochemical (IHC) staining for residual CLL cells, and therapy was stopped if there was no radiological or IHC evidence of residual CLL (stringent CR). Patients with residual disease received a 3rd cycle of therapy. Results Forty-one patients were enrolled (July 2008 - February 2013) and all 39 who started therapy were evaluable for response: Median age 61 years (range 47-78), 30 (77%) males, 36 (92%) relapsed/refractory CLL (median prior regimens = 2, range 1-10), 3 (8%) previously untreated, 23 (59%) advanced stage (Rai III-IV), 16 (41%) intermediate stage (Rai I-II). Prognostic factors: FISH (hierarchical classification) 15 (38%) 17p13-, 6 (15%) 11q22-, 5 (13%) 12+, 3 (8%) no defects, 8 (21%) 13q14-, and 2 (5%) other abnormalities, IGHV analysis (n=38) 27 (71%) unmutated (<2%), ZAP-70 (n=37) 28 (76%) positive (>20%). Thirty (77%) patients completed planned therapy (28 had 3 cycles, 2 had 2 cycles with stringent CR). Nine patients received one (n=4) or two (n=5) cycles of therapy because of disease progression or complications. Grade 3-4 hematological adverse events (n=37) at least possibly related to treatment included neutropenia (n=22), thrombocytopenia (n=11), anemia (n=2) and hemolysis (n=2). Non-hematological adverse events (n=17) included infections/neutropenic fever (n=8), fatigue (n=3), and hemorrhage (n=2). CMV reactivation was detected and treated in 14 patients (grade 1-2). No patients died during treatment or from treatment related complications. The overall response rate was 56% (95% CI 40-72) with 4 (10%) CR, 7 (18%) CRi, 11 (28%) PR, 7 (18%) SD, and 10 (26%) PD. Four patients (3 CR and 1 CRi) had IHC negative bone marrow studies. Thirteen (33%) patients have died due to progressive CLL (n = 11), sepsis (n=1), and pneumonia (n=1). Median follow up for surviving patients is 23 months (range 3-55). Seven (18%) patients proceeding to RIC allogeneic transplant were censored for time to next treatment. Twenty-one (54%) patients required therapy for progressive CLL and 7 (18%) have required no further therapy. Median progression free survival was 7 months (95% CI: 5-16), time to next treatment 9 months (95% CI: 6-27) and median overall survival has not been reached. Discussion PAR was effective and tolerable therapy for high-risk CLL. This study suggests that alemtuzumab can be used safely in combination with a purine analogue in a short-duration regimen. Disclosures: Zent: Genentech : Research Funding; Genzyme: Research Funding; Biothera: Research Funding; GlaxSmithKline: Research Funding; Novartis: Research Funding. Off Label Use: Pentostatin therapy for CLL, use of lower doses of rituximab.

Abstract Background: CLL patients (pts) treated with novel targeted therapies continue to experience disease progression. Approximately 7-15% of relapsed CLL treated with ibrutinib or venetoclax developed Richter's syndrome (RS), an aggressive high grade lymphoma transformation. Standard chemotherapy has limited efficacy in RS. We hypothesized that checkpoint blockade would re-establish anti-tumor immune response in progressive CLL/RS and here we aim to update the clinical data and correlative analysis of MC1485: a phase 2 study of PD-1 blocking antibody pembrolizumab in relapsed/refractory CLL and RS. Methods: Relapsed/refractory CLL including RS enrolled in the CLL arm of MC1485 trial was reported here. The primary end point of this study is overall response rate (ORR). Pts with prior allogeneic stem cell transplant were excluded. Pembrolizumab 200 mg was administered intravenously every 3 weeks. NCI CTCAE v4.0 and IWCLL 2008 criteria were used for non-hematological adverse events (AE) and for CLL grade hematological AE. Tumor expression of PD-1 and PD-L1 were assessed with standard immunohistochemical (IHC) staining. Percentage expressions of individual antigens were analyzed with whole-slide scanning followed by image analysis with Image-Pro software (Media Cybernetics). Fluorescence in situ hybridization (FISH) was performed on available CLL/RS tissue sections to assess copy number of chromosome 9p region that contains PD-L1 and PD-L2. Results: 25 pts including 16 CLL and 9 RS (biopsy-proven large cell lymphoma) were enrolled in CLL arm. The median age was 69 years (46-81). Twelve (48%) pts had del(17p) or monosomy 17 or TP53 mutation. The median number of prior therapies was 4 (1-10). 96%, 72% or 48% of pts had received alkylator and anti-CD20 antibody, purine analog or anthracycline. Fifteen (60%) pts had prior ibrutinib and 12 (48%) progressed clinically while receiving ibrutinib, including 6 who progressed to RS and 6 who developed progressive CLL. The median number of pembrolizumab doses that pts received was 3 (1 to 21), administered over a median treatment duration of 11 weeks (1 to 56). Drug-related AE occurred in 21 pts (88%) with the most common ones being neutropenia in 9 (37%), cough in 7 (29%) and dyspnea in 6 (25%) pts. Drug-related grade 3 or above AE occurred in 9 (38%) pts with most common ones being thrombocytopenia (5, 21%), dyspnea (2, 8%), and fatigue (2, 8%). The most common immune-related AE was liver enzyme elevation (12%, 8% G3) and was reversible with therapy interruption or steroid therapy. Based on investigator assessment using the Revised Response Criteria for Lymphomas and IWCLL 2008 criteria, one RS pt had complete response (CR, 4%), 3 RS had partial responses (PR, 12%). Among 9 RS pts, 1 CR (11%), 3 PR (33%), 3 SD (33%) and 2 PD (22%) were observed. Thus the ORR in RS was 44%. No CLL pts achieved a CR/PR, 3 had SD and 9 had progressive disease (PD). The ORR of all pts was 16%. Of the 4 RS who had CR/PR, responses occurred early after 2 cycles of therapy and median duration of therapy for CR/PR pts was 8.3 months with data cut-off by June 30th 2016 (Figure 1A). The causes for therapy discontinuation in RS were PD (3, 33%), alternate therapy (2, 22%), and thrombocytopenia due to increased marrow CLL (1, 11%). Increased marrow CLL was observed in 2 RS pts with PR to RS phase of disease assessed by PET, thus the protocol was amended to allow addition of idelalisib/ibrutinib to control the underlying marrow CLL. For RS pts who had a CR/PR or SD, variable nodal responses were observed (Figure 1B). In particular, 6 RS who had prior ibrutinib experienced CR or PR or SD with nodal responses. After a median follow-up of 10.2 (1.9 to 16.1) months, the median overall survival (OS) for all pts was 10.7 months (95% confidence interval [CI], 5.4 to not reached). The 6 month OS rate for RS and CLL pts were 73% and 59%, respectively. Biomarker assessment using IHC analysis on 10 pts with available tumor/nodal tissues (6 RS and 4 CLL) showed an increased expression of PD-L1 (p = 0.02) and a trend for an increased expression of PD-1 (p = 0.1) in the group of pts with CR/ PR versus pts in the group with no clinical response. One out of 10 tested showed polysomic for chromosome 9p. Conclusion: Pembrolizumab had an acceptable safety profile in CLL and RS patients. We confirmed that pembrolizumab has substantial therapeutic activity in RS. Single-agent pembrolizumab does not appear to have clear activity in CLL. Disclosures Ding: Merck: Research Funding. Parikh:Pharmacyclics: Honoraria, Research Funding. Shanafelt:GlaxoSmithKline: Research Funding; Genentech: Research Funding; Janssen: Research Funding; Pharmacyclics: Research Funding; Celgene: Research Funding; Cephalon: Research Funding; Hospira: Research Funding.

Abstract Abstract 1792 High risk disease can be identified in patients with early stage chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL) using biological prognostic markers. We have shown that early therapy of high risk CLL patients with alemtuzumab (ALM) and rituximab (RTX) is effective and could possibly delay first standard treatment (Cancer 2008;113:2110-8). Efficacy of unconjugated monoclonal antibody (mAb) therapy in these patients could be improved by enhancing mAb mediated cellular cytotoxicity. Preclinical studies show that yeast cell wall derived beta glucan, which increases complement receptor 3 (CR3) binding to the complement fragment iC3b on target cells, could increase mAb mediated cellular cytotoxicity. Both ALM and RTX activate complement resulting in deposition of iC3b on the cell membrane. In CLL cells that are not lysed by complement activation, these iC3b molecules are targets for the effector cells mediating cellular cytotoxicity. We hypothesized that PGG beta glucan (Imprime PPG®, Biothera, Eagan MN) an intravenous formulation of a 1,3/1,6 glucose polymer prepared from a strain of Saccharomyces cerevisiae, would improve the efficacy of therapy with ALM and RTX in patients with CLL by increasing CR3 binding to iC3b and thus enhancing macrophage, neutrophil, and NK cell mediated cytotoxicity. We report the results of a Phase I study of the combination of ALM, RTX and PPG beta glucan in patients with CLL. Methods: The primary aim of this IRB approved study (NCT01269385) was to determine the maximum tolerated dose (MTD) of PGG beta glucan that could be safely combined with ALM and RTX. The MTD was defined as the PGG beta glucan dose level below that which induced dose limiting toxicity in at least one third of patients, or the highest dose level tested if all levels were tolerated. Eligibility for the trial required a diagnosis of CLL by standard (IWCLL-NCI 2008) criteria, no prior treatment for CLL, high risk CLL based on molecular markers, absence of standard indications for initiation of therapy for CLL, and adequate performance status and organ function. High risk CLL was defined as at least one of the following: 17p13-; 11q22-; either unmutated (<2%) IGHV or use of VH3–21 as well as CD38+ and/or ZAP70+. Patients received standard premedication for mAb, antimicrobial and allopurinol prophylaxis and weekly PCR testing for CMV reactivation with treatment of viremia. The duration of treatment was 33 days. PGG beta glucan was administered IV on days 1, 5, 10, 17, 24, and 31 and the first dose was premedicated with hydrocortisone 100mg IV, oral acetaminophen 1000 mg and diphenhydramine 50 mg. The starting dose level of PGG beta glucan was 1 mg/kg, 2nd dose level was 2 mg/kg and the 3rd dose level 4 mg/kg. Subcutaneous ALM therapy started on day 3 with daily dose escalation (3 – 10 – 30 mg) and then 30 mg Mon-Wed-Friday for 4 weeks. Weekly RTX started on day 10 at 375 mg/m2 IV × 4 doses. Results: Thirteen patients were enrolled from February 2011 to April 2012. The 11 evaluable patients had a median age of 61 years (range 47 – 77), 73% were male, 3 had early stage disease (Rai 0) and 8 had intermediate stage disease (Rai I n = 7, Rai II n = 1). High-risk parameters were 17p- in 4 patients, 11q22- in 3 patients, and unmutated IGHV and expression of ZAP70 and/or CD38 in 4 patients. There were no dose limiting toxicities. One patient had grade 4 febrile neutropenia, with no grade 3–4 anemias or thrombocytopenias, and there were no grade 3–4 non-hematological toxicities. All patients responded to therapy with 7 CR, 1 CCR, 1 nPR, and 2 PR (IWCLL-NCI 2008 criteria). Median follow up was 6.9 months (2.3 – 13.2) and one patient progressed at 9.7 months. No patients have required treatment for progressive disease and there have been no patient deaths. Two patients were not evaluable: One developed neutropenia and therapy was not held per protocol, and the other developed a grade 2 skin reaction to ALM and treatment was stopped. Discussion: The combination of PGG beta glucan with ALM and RTX is well tolerated at a PGG beta glucan dose of 4 mg/kg. All patients responded to therapy with 64% achieving a CR. These data support continuation of this study in a phase II component. Acknowledgment: This study was funded by the University of Iowa/Mayo Clinic Lymphoma SPORE (CA097274) and Biothera. Disclosures: Zent: Biothera: Research Funding; Genzyme: Research Funding; Genentech: Research Funding; Novartis: Research Funding; GlaxoSmithKline: Research Funding. Off Label Use: Phase I study using PGG beta glucan in CLL.

Abstract Background: Individuals with clinically ascertained monoclonal B-cell lymphocytosis (c-MBL) having the phenotype of the chronic lymphocytic leukemia (CLL) have a 1-4% per year risk of progression to CLL requiring therapy. The risk factors for progression and the outcomes of individuals with c-MBL are not well defined. Methods: Using the Mayo Clinic CLL Database, we identified individuals with c-MBL (absolute B-cell count of <5x109/L, in the absence of symptoms, organomegaly, splenomegaly and cytopenias) who were seen at Mayo Clinic, Rochester, MN between 01/1995 - 5/2016. Patients in whom an absolute B-cell count was not available were included in the analysis if the absolute lymphocyte count was <5x109/L. Baseline clinical characteristics and prognostic test results (including IGHV mutation status, genetic abnormalities detected by FISH, and expression of ZAP-70, CD38 and CD49d) were recorded. Time to first therapy (TFT) was analyzed using cumulative incidence methods accounting for competing risk of death. Multivariable Cox proportional hazards regression analysis was used to identify factors that predicted TFT. Because of missing data for some prognostic parameters, multiple models were run, introducing one novel prognostic factor at a time to the base model (which consisted of age and sex). Overall survival (OS) of these individuals was compared to age- and sex-matched population of the state of Minnesota. Results: Eight hundred and fifty-one individuals with c-MBL were identified and included in this analysis. Median age was 69 years (range, 38-95 years), and 527 (62%) were males. The median absolute B-cell count at the time of diagnosis was 2.6 x 109/L (range, 0.1-5.0 x 109/L). The median serum beta-2 microglobulin (β2M) was 2.2 mg/dL (range, 1.0 - 21.5 mg/dL). One hundred and nine (30%) individuals had unmutated IGHV genes, and 38 (7%) had high-risk FISH (defined as either del17p13 or del11q23). The CD38 (≥30%), ZAP-70 (≥20%), and CD49d (≥30%) status was positive in 19%, 23% and 34% individuals, respectively. After a median follow-up of 6.8 years, 99 individuals required therapy for progressive disease (at a rate of 2.1% per year, Figure 1). On multivariable analysis, the following factors were associated with a higher risk of progression to CLL requiring therapy: a) unmutated IGHV status (hazard ratio [HR]:3.8, 95%CI 2.1 - 7.0, p<0.0001); b) positive CD49d status (HR: 3.1, 95%CI 1.6 - 5.9, p=0.0006); and c) positive CD38 status (HR: 2.8, 95% CI 1.7 - 4.8, p<0.0001). Although the HR for high-risk FISH was 2.0 (95% CI 0.9 - 4.4), it was not significantly associated with TFT (p=0.11), likely due to small sample size. Age, sex, serum β2M, and ZAP-70 expression were not predictive of TFT. Among these individuals with B-cell counts <5x109/L, further stratification of the absolute B-cell count at diagnosis showed no association with TFT (Figure 2). The median OS of individuals with c-MBL was 11.8 years. Although the OS among individuals with c-MBL and the age- and sex-matched general population of Minnesota appeared similar for the first 10 years of follow-up, OS was significantly shorter in the c-MBL group during the full follow-up interval (p=0.004, Figure 3). Conclusion: In this large cohort of individuals with clinically ascertained MBL, the risk of progression to CLL requiring therapy was 2.1% per year. Biological characteristics of the B-cell clone including IGHV mutation status, and CD49d and CD38 status predicted time to first CLL therapy. On extended follow-up, the OS of individuals with c-MBL was significantly shorter relative to age- and sex-matched general population. These findings have important implications for counselling individuals with clinically ascertained MBL. Disclosures Parikh: Pharmacyclics: Honoraria, Research Funding. Ding:Merck: Research Funding. Kenderian:Novartis: Patents & Royalties, Research Funding. Shanafelt:Pharmacyclics: Research Funding; GlaxoSmithkKine: Research Funding; Janssen: Research Funding; Genentech: Research Funding; Celgene: Research Funding; Cephalon: Research Funding; Hospira: Research Funding.