Citations

Abstract BACKGROUND: Karyotype analysis of metaphase cells for discovering genome-wide cytogenetic abnormalities has played an important role in prognosis and counseling of patients with chronic lymphocytic leukemia (CLL). Due to the low proliferative rate of CLL B cells, karyotype analysis has been of limited clinical utility in this disease. Thus, fluorescence in situ hybridization (FISH) on interphase cells has replaced karyotype analysis for the assessment of recurrent genetic changes in CLL. Recently, immunostimulatory CpG-oligodeoxynucleotides (CpG) have been shown to induce primary CLL B cell proliferation via engagement of toll-like receptor 9 (TLR9), thereby rendering karyotype analysis feasible and providing for a useful and reliable method to discover new cytogenetic abnormalities in CLL B cells. However, we and others have shown that CpG stimulation of CLL and normal B cells also induces robust expression of activation induced cytidine deaminase (AID), a mutagenic enzyme that is linked to the development of cytogenetic abnormalities. It is therefore plausible that cytogenetic abnormalities observed following CpG stimulation of CLL B cells may not reflect de novo abnormalities but rather reflect CpG induced-AID mediated cytogenetic alterations. We began to address this possibility by assessing the effects of CpG stimulation on the karyotypes of normal blood B cells. HYPOTHESIS: Since CpG stimulation induces AID expression in CLL and normal B cells, we hypothesize that: robust B cell activation by CpG could result in cytogenetic abnormalities thereby contributing to lymphomagenesis; and if CpG induces cytogenetic abnormalities that are linked to disease initiation and/or progression, such information would be of great value in the interpretation of cytogenetic data obtained from CpG-stimulated CLL B cells. METHODS: We performed interphase FISH analysis on freshly isolated blood B cells, and metaphase karyotype analysis on CpG stimulated B cells from 17 healthy blood donors. Pure (>98%) B cells obtained by negative selection, were hybridized at isolation with a probe set to identify deletion 6q, 11q, 13q, and 17p, trisomy 12, and IGH gene rearrangements, and cells were also stimulated for 5 days with 10 μg/ml CpG (CpG 2006, synthesized in-house) plus IL-2 and IL-15 for metaphase analysis. At least 20 post-CpG metaphase spreads were analyzed for each sample and abnormalities were considered clonal using the accepted convention (gains or translocations are present in two or more cells and loss present in at least 3 cells). The expression of AID in the B cells pre- and post-CpG stimulation was assessed by RT-PCR. RESULTS: FISH analysis of freshly isolated B cells showed that all 17 subjects were normal. After CpG stimulation, all samples examined exhibited strong AID expression as revealed by RT-PCR. By karyotype analysis, none of the 17 CpG stimulated samples showed evidence of clonal abnormalities. However, one or more nonclonal chromosomal abnormalities were observed in 7 out of 17 (41.2%) samples. Among those 7 samples, 4 samples had 1 abnormal metaphase out of a minimum of 20 examined while the other 3 samples exhibited two or more cells, each with distinct abnormalities. Some of those nonclonal abnormalities have also been observed in CLL (i.e., trisomy 3, trisomy 12 and 14q32 rearrangements). This is a much higher incidence of nonclonal abnormalities than has been seen with peripheral blood cells cultured by other methods. CONCLUSION: Our data have significance for the biology of CLL and for clinical practice. First, our data suggest that signaling through TLR9, and perhaps other receptors that likewise induce robust B cell AID expression, may represent a natural mechanism by which B lineage cells acquire chromosomal abnormalities during normal immune responses that may predispose toward neoplastic transformation. Second, given that none of the CpG-induced metaphases in normal B cells resulted in clonal abnormalities in the 5 day timeframe, our data also validate the clinical utility of CpG as a valuable tool for the cytogenetic analysis of CLL B cells since only clonal abnormalities are currently scored. However, it remains possible that non-clonal abnormalities seen in CpG-stimulated CLL B cells may be relevant to the disease process if future work shows that CpG stimulation uncovers recurring non-clonal defects of chromosomes/genes associated with tumorigenic events.

Abstract Background: Normal and tumor stem cells are characterized by high activity of multidrug resistance (MDR) transporters. One of these, ABCG2 (ATP-binding cassette, sub-family G member 2 protein), is an ATP dependent transporter and putative stem cell marker responsible for verapamil sensitive Hoechst efflux. While ABCG2 is known to be expressed in normal and leukemic stem cells, as well as a small population of normal lymphocytes and some B-cell malignancies, its expression in chronic lymphocytic leukemia (CLL) is unknown. It has been postulated that leukemic stem cells due to their quiescent nature and expression of MDR transporters represent a population resistant to therapy and that this residual population is critical for tumor persistence and recurrence. Hypothesis: We hypothesized that ABCG2 is expressed in a small percentage of primary CLL B cells; gene expression profiles of ABCG2 positive versus ABCG2 negative CLL B cells differ in respect to expression of self renewal and lymphoid development genes; the frequency of ABCG2+ CLL B cells increases after treatment in patients responding to therapy. Methods: We analyzed ABCG2 expression by primary CD5+, CD19+ CLL-B cells from untreated CLL patients of all Rai stages by flow cytometry. In a subset of patients we used fluorescence activated cell sorting (FACS) to sort CD19+, CD5+ ABCG2+ and CD19+, CD5+ ABCG2- cells. Gene expression profiling was then performed using the U133 plus 2.0 Affymetrix microarray platform. In a separate cohort of patients treated in a clinical trial of pentostatin, cyclophosphamide and rituximab (PCR), the percentage of ABCG2+, CD19+, CD5+, CD79b dim cells at baseline and then two months after completion of 6 cycles of PCR therapy where patients had minimal residual disease (MRD) was assessed and correlated with clinical response. Results: ABCG2+ CD19+, CD5+ detectable populations were seen in all 20 CLL assessed patients (median percentage 0.6%; range 0.08%–3.8%). There was no difference in percentage of ABCG2+ cells based on Rai stage, IGVH mutational status, Zap70 or CD38 expression. Preliminary analysis of the gene expression profiling of ABCG2 positive versus negative CLL B cells from four randomly selected patients revealed significantly higher expression of genes associated with self-renewal, cell cycle and early B-cell development including: cyclin-dependent kinase inhibitor 1C (CDKN1C, p=0.034), transcription factor 7-like 2 (TCF7L2, involved in WNT pathway regulation, p=0.016), beta-catenin (p=0.034) and pre-B-cell colony enhancing factor 1 (PBEF-1, p=0.037). Flow based assessment of the levels of ABCG2 positive populations at baseline and after therapy with PCR in patients with minimal residual disease showed a dramatic increase in frequency of ABCG2 positive CLL B cells. The percentage of ABCG2+ cells went from a median level of 0.19% (range 0.04%–0.19%) prior to therapy to a median level of 10.93% (range 0.15%–25.12%), p<0.001. In contrast two patients who did not reach MRD (partial responses by NCI-WG criteria) had no significant increase in percentage of ABCG2 positive cells (0.14%; 0.23% and 0.16%; 0.21% prior and after therapy, respectively, p=0.68). Conclusion: Our data indicate that ABCG2 positive CLL B-cells constitute 0.1–3.8% of circulating CLL B-cells in untreated patients. The frequency of ABCG2+ CLL B-cells appears to dramatically increase after therapy in the MRD state; this could be related to their relative resistance to therapy and/or a shift from extravascular compartments post therapy. Since ABCG2 positive CLL B-cells demonstrate expression of early B-cell development and self-renewal genes we believe that that this population could represent a putative self renewing CLL B-cell compartment. Further studies to characterize features of ABCG2 CLL-B –cells in relation to their capacity to be self renewing and resistance to therapy are warranted.

Abstract Acquired pure red cell aplasia (APRCA) is associated with a number of conditions including malignancies, infections and autoimmune disorders. APRCA also occurs in patients with T-LGLL. It is postulated that suppression of erythropoiesis in T-LGLL is related to the immune destruction of erythroid precursors by the LGL clone. We hypothesize that APRCA can be associated with clonal T-cell expansion without pathological evidence of T-LGLL. Methods: We identified patients who were diagnosed with APRCA and had clonal TCR gene rearrangements. Clinical course, bone marrow pathology and flow cytometry data were reviewed. Immunohistochemical studies were performed on available bone marrow biopsies using antibodies to CD3, CD8, CD20 and the cytotoxic granule proteins TIA-1 and granzyme B. Clonal TCR gene rearrangements were detected by PCR and Southern blot. The diagnosis of APRCA was based on the absence of erythroid progenitors, with intact granulo- and thrombopoiesis. A pathologic diagnosis of T-LGL leukemia was established by the presence of clonal TCR gene rearrangements and an immunophenotypically distinct CD8 positive T-cell population as previously described. The diagnostic flow cytometric features included abnormal patterns of T-cell antigen expression and aberrant co-expression of NK-cell antigens. Immunoperoxidase features supportive of a diagnosis of LGL were the presence of interstitial clusters or intravascular staining of cells positive for CD8 and TIA-1 and/or granzyme B. Results: We identified 28 patients with APRCA and the presence of clonal TCR gene rearrangements seen at Mayo Clinic Rochester between 7/1/1991 to 6/1/03. All patients presented with a transfusion dependent anemia (median hemoglobin 7.8 g/dL, range 3.6–10.3). Tissue was available for immunohistochemical studies for 21 cases. 13 of 21 patients (61%) had an immunophenotypically abnormal T-cell population which, in conjunction with the clonal TCR gene rearrangements were considered diagnostic of T-LGL. 8 patients (39%) had no pathological evidence of T-LGLL despite clonal TCR gene rearrangement studies. The most commonly used treatment consisted of oral cyclophosphamide which was used in 14 of 21 patients (8 and 6 in patients with and without pathological evidence of T-LGLL respectively). A normalization of hemoglobin was seen in 11 patients (6 and 5 in patients with and without evidence of T-LGLL respectively). Median duration of response was 30 months (range 22–120). None of 8 patients with APRCA and clonal TCR gene rearrangements without evidence of LGLL at the the time of initial diagnosis developed overt T-LGLL during follow up (median 64 months, range 30–118). Discussion: 39 % of patients with APRCA and evidence of clonal TCR gene rearrangements did not meet pathological criteria for diagnosis of T-LGLL. There was no apparent difference in disease presentation and response to therapy in patients with or without pathological evidence of LGLL. The significance of the presence of clonal TCR gene rearrangements in the absence of a detectable immunophenotypically abnormal T-cell population is unclear. It is possible that T-LGL was present which could not be detected by our analyses. Alternatively, the clonal TCR gene rearrangements could be indicative of a pertubation of the T-cell compartment related to an autoimmune disorder causing the APRCA. The fact that none of the patients developed progression to overt LGLL supports the latter possibility.

Abstract Background: Cytotoxic T-cell infiltrates are a nearly universal finding in the bone marrow of patients with multiple myeloma. It has been postulated that presence of T-cells in the bone marrow of multiple myeloma (MM) patients represents an immune response against the tumor and therefore, might be associated with an improved prognosis. However, the impact of bone marrow T-cells on the prognosis of multiple myeloma patients has not been studied systematically. Methods: Bone marrow biopsies of patients with newly diagnosed multiple myeloma were stained by immnohistochemistry for the CD8 antigen and reviewed by a blinded hematopathologist. Three high power fields are reviewed for each biopsy and the total number of CD8 positive cells counted and reported. For patients with more than 300 cells per 3 fields, results were reported as >300. The number of bone marrow CD8 positive cells was then correlated with patients’ clinical data, including other prognostic factors and overall survival. Results: Bone marrow biopsy specimens from 100 patients, performed within the week of a diagnosis of multiple myeloma and collected between May 1998 and January 2001 were evaluated. The median number of CD8 positive cells was 270 (33 – >300). Patients’ characteristics are shown in Table 1. Median follow up was 30 months (0–80). The number of cytotoxic T-cells as a continuous variable was a risk factor for shortened overall survival, HR 1.86 (95% CI 1.11–3.35). Using minimal p value approach, the cutoff of 270 cells (the median) risk stratified patients into two groups: the median survival of patients with > 270 CD8 positive cells was 16 months vs. 48 months in patients with ≤270 cells, p=0.005 (Figure). In multivariate analysis including age, B2M, albumin, CRP, bone marrow plasma cell percentage and plasma cell labeling index, the number of cytotoxic T-cells was an independent predictor of overall survival was HR 3.1, p=0.0017. Conclusion: We show that the number of cytotoxic T-cells in the bone marrow is a strong and independent prognostic factor in patients with newly diagnosed multiple myeloma. Our observation does not contradict the hypothesis that cytotoxic T-cells participate in an immune response against the tumor since our findings may represent a higher level of immune response associated with baseline aggressive disease biology. However, our study suggests for the first time that increased marrow cytotoxic T-cells have an adverse effect on outcome in myeloma, and suggest that these cells may have a direct facilitating effect on tumor growth and on the marrow microenvironment. Further studies of the biology of behind this observation are warranted. Characteristic N Median (range) Gender male 61 CRP 81 0.4mg/L (0.01–11.2) Albumin 99 3.6 g/dL (2.6–5.4) B2microglobulin 94 4.0 (0.9–28) μg/mL Marrow PC% 90 45% (11–99) PC labeling index 90 high (>1%) 36 BM CD8 cells 100 270 (33 – >300) ISS 94 1 19 2 41 3 34 Figure Figure

TPS7569 Background: Progress in genome technology allows analysis of previously completed trials to identify patients subgroups potentially benefiting from therapy. Enzastaurin is a potent inhibitor of protein kinase C beta (PKC- b) and suppresses the phosphoinositide 3-kinase (PI3K)/AKT pathway. The safety and efficacy of Enzastaurin has been tested in more than 60 clinical trials including 2 major studies in DLBCL: (1) PRELUDE (A phase III maintenance trial of Enzastaurin vs Placebo, N=758) ( Crump, 2016), and (2) S028 (A randomized phase II study of Enzastaurin/R-CHOP vs R-CHOP in frontline intermediate/high-risk DLBCL, N=101) ( Hainsworth, 2016). DNA samples extracted from blood of patients from PRELUDE were retrospectively genotyped using whole genome SNP arrays. From the genome wide screening a novel genetic biomarker, DGM1, was identified showing high correlation with response to Enzastaurin treatment ( Luo, ASH 2018). Importantly, these findings were replicated in the phase II S028 study. In the S028 study the hazard ratio (HR) for OS in high-risk (IPI ≥ 3) DGM1 positive (+) patients who received Enzastaurin/R-CHOP was 0.28 (0.1-0.81) when compared to subjects who received R-CHOP, a benefit favoring Enzastaurin (p=0.018). These data suggest that addition of Enzastaurin to R-CHOP may significantly improve outcome in frontline high-risk DGM1 (+) DLBCL. The ENGINE study was initiated to validate this finding in a prospective study. Methods: Adult patients must have untreated CD20+ DLBCL, IPI ≥ 3. Patients are randomized 1:1 to Enzastaurin/R-CHOP or Placebo/R-CHOP for 6 cycles during combination phase. Each subject’s treatment assignment will be unblinded after response assessment at the end of the combination phase. Subjects randomized to the investigational arm who have a complete or partial response will have the option to continue in the single agent phase to receive Enzastaurin for up to 2 additional years. The study intends to enroll approximately 235 patients with primary endpoint of OS in DGM1 (+) patients. The study is ongoing with 51 sites open in the US and China. As of 22 Jan 2019, 70 patients have been randomized. Clinical trial information: NCT03263026.

7556 Background: The frontline treatment for advanced follicular lymphoma has evolved with the introduction of maintenance therapy, bendamustine (Benda), obinutuzumab (G), and lenalidomide (Len). We conducted a network meta-analysis of phase 3 randomized controlled trials (RCTs) to identify the regimens with superior efficacy. Methods: Data were extracted from 7 RCTs (FOLL05, StiL NHL1, BRIGHT, PRIMA, GALLIUM, StiL NHL7, and RELEVANCE). Progression-free survival (PFS) was compared between 11 regimens with different immunochemotherapy and maintenance strategies. To incorporate direct and indirect comparisons, random-effects Bayesian network meta-analyses were conducted after adjusting for study-wise variation. The posterior inference was derived based on Markov chain Monte Carlo methods and implemented using JAGS v4.3.0. Pairwise comparison of hazard ratios (HRs) and 95% credible intervals (CIs) were calculated. Results: PFS HRs of other regimens compared to the reference regimen are summarized in the Table. Compared to Rituximab(R)-Benda, R-CHOP had inferior PFS, R-CHOP-R, G-CHOP-G, and R-Len-R had similar PFS, while R-Benda-R, R-Benda-R4 and G-Benda-G had better PFS. Compared to R-CHOP-R, G-CHOP-G and R-Len-R had similar PFS, while R-Benda-R, R-Benda-R4 and G-Benda-G had better PFS. In addition, the PFS for G-Benda-G was similar to R-Benda-R4 (HR 0.94, 95% CI 0.78-1.09) but better than R-Benda-R (HR 0.82, 95% CI 0.75-0.97). Conclusions: Compared with the commonly used R-Benda and R-CHOP-R regimens, G-CHOP-G, R-Benda-R and R-Benda-R4 had better PFS, while the chemotherapy-free regimen R-Len-R had similar PFS. [Table: see text]

7554 Background: Predicting early clinical failure in patients with untreated FL is important but difficult. Lymphoma involvement of EN sites is better detected by FDG-PET/CT than CT alone, but PET parameters are not part of the usual predictive indices. We aimed to determine the incidence and patterns of spleen and EN disease using PET/CT, and learn if they are useful in predicting early clinical failure. Methods: PET/CT images from 613 cases of newly diagnosed FL between 2003 – 2016 were retrospectively reviewed. The location, pattern, and number of EN sites, as well as splenic involvement, were recorded. Associations with outcomes were assessed using event-free survival (EFS) and overall survival (OS). Results: 49% (301/613) of patients had PET/CT-detected EN involvement, and 28% (171/613) had spleen involvement. Presence of ≥2 EN sites, spleen, bone, or soft tissue involvement, as well as a multifocal on diffuse pattern of bone involvement by imaging, were univariate predictors of EFS; presence of ≥2 EN sites and bone involvement pattern were also predictive of OS. In a multivariate analysis with FLIPI-2 factors, spleen involvement, pattern of bone involvement, and soft tissue involvement independently predicted a lower EFS (Table). When the multivariate analysis was performed using PRIMA-PI factors, the presence of ≥2 EN sites was an adverse independent prognostic factor for OS (HR 2.28; 95% CI 1.01-5.18; p=0.05). Conclusions: Baseline PET/CT identifies EN and spleen sites of disease that can predict early clinical failure of FL. These results may be useful to better identify high-risk patients and guide appropriate therapy. [Table: see text]

7520 Background: We report results of a phase 2, open-label study of durvalumab (durva) in combination with R-CHOP or R2-CHOP (R-CHOP + lenalidomide) in previously untreated, high-risk diffuse large B-cell lymphoma (DLBCL). Methods: Subjects (≥18 y; ECOG 0–2) with previously untreated, high/high-intermediate risk DLBCL (IPI ≥3/NCCN-IPI ≥4) were stratified to durva + R-CHOP (Arm A, GCB DLBCL) or R2-CHOP for 6–8 cycles (Arm B, ABC DLBCL) based on cell of origin identified by gene expression followed by durva consolidation up to month 12 from start of induction. After FDA placed clinical holds on trials including combination therapy with checkpoint inhibitors and immunomodulatory agents, the study was revised to include both ABC and GCB in Arm A (durva + R-CHOP). The primary endpoint was complete response rate (CRR) at end of induction; secondary endpoints were rate of subjects continuing to consolidation, safety, and response in biological. Results: A total of 46 subjects were treated (safety; A/B, n=43/3); median age, 62/66 y; male, 61%/67%; ECOG 2, 19%/33%; Ann Arbor stage IV, 79%/33%; bulky disease: 49%/67%; double/triple-hit lymphoma, 30%/33%. As of Aug 2, 2018, 30/3 (A/B) had completed induction therapy, and 19 subjects (A) were ongoing. CRR (95% confidence interval) at end of induction was (A) 54% (37%-71%) and (B) 67% (9%-99%); 68%/67% (A/B) continued to consolidation therapy and were progression free at month 12. Safety profile was as expected for the components of the combination regimen with no new safety signal identified. Frequent treatment-emergent adverse events (TEAEs; ≥25%; A+B) included fatigue (61%), neutropenia (52%), peripheral sensory neuropathy (50%), nausea (46%), diarrhea (28%); constipation, decreased appetite, insomnia, pyrexia (24% each); and alopecia, dizziness, dyspnea, headache, stomatitis (22% each). Grade 3/4 TEAEs occurred in 84%/100% of subjects (A/B), and 3 subjects (2/1) died with no death related to study treatment. Follow-up for efficacy and safety is ongoing. Conclusions: Durva + R-CHOP combination therapy is safe and demonstrates encouraging response rates in subjects with high-risk DLBCL including double-hit lymphoma. Clinical trial information: NCT03003520.

7514 Background: Relapse is expected in treated indolent lymphoma patients, and an unmet need exists to prolong remission with effective therapies. Lenalidomide + rituximab (R2) may improve the efficacy of next treatment by their unique mechanisms. Methods: The AUGMENT phase III study evaluated patients with R/R FL gr 1-3a (82%) and MZL (18%) after ≥ 1 prior systemic therapy (not rituximab refractory). Randomization was 1:1 to R2 (lenalidomide PO 20 mg/d, d1-21/28 X12 cycles [c] + rituximab [R] IV 375 mg/m2/wk, c1, d1, 8, 15, 22 and c2-5, d1) and R/placebo (same dosing schedule). The primary endpoint was PFS by 2007 IWG; secondary/exploratory analyses were time to next antilymphoma/chemotherapy treatment (TTNLT/TTNCT) and response to next treatment. Per regulatory guidance, PFS2 was defined as time from randomization to first PD or death from any cause after next antilymphoma treatment, or initiation of a third antilymphoma treatment. Results: Median PFS was superior for R2 over R/placebo (39.4 vs 14.1 mo; HR = 0.46; P < 0.0001). As of 22June2018, median TTNLT, TTNCT, and PFS2 were not reached for R2, and were significantly longer than R/placebo (HR = 0.54, 0.50, and 0.52, respectively). For 49/178 (28%) R2 and 80/180 (44%) R/placebo patients receiving next antilymphoma therapy, response was generally higher with R2 (57% ORR; 31% CR) than R/placebo (36% ORR; 16% CR; Table). Conclusions: These analyses suggest that R2 (vs R/placebo) prolonged time to subsequent treatment and is associated with longer PFS2, enabling greater response to next therapy. Although patient numbers were modest, it is hypothesized that patients who received R2 were generally more sensitive to subsequent therapy than those treated with R/placebo. Clinical trial information: NCT01938001. [Table: see text]