ALBERT

Description: Introduction: Multiple myeloma (MM) is a patchy bone marrow based malignancy of plasma cells, resulting in painful bone lytic lesions that can be visualized by 18F-FDG-PET-CT. We treated 45 NDMM patients with CRd-R therapy that resulted in high rates of minimal residual disease (MRD) negativity (62%)(Korde et al. JAMA Onc 2015). In this study, we assessed longitudinal FDG response through lenalidomide (Len) maintenance period and aimed to correlate with clinical findings and MRD status. Methods: The details of treatment received, study design and patients' characteristics have already been published. As part of the study design, all patients had serial PET imaging at baseline, after achievement of CR and/or at completion of 8 cycles of CRd, and at year-1 and -2 of Len maintenance, or termination of protocol therapy. Whole body (vertex to toes) static FDG imaging was performed at 1-hour post injection, implemented according to institutional practice. Focal lesions on FGD were defined as: increased uptake (above background reference) within the bone, (excluding articular regions due to high prevalence and likelihood of confounding arthritic disease), maximum standardized uptake value (SUV) 〉1.5 for lesion size on CT ranging from 0.5-1.0 cm, or maximum SUV 〉2.5 for lesions 〉1.0 cm. Results: At baseline, 37/45(82.2%) patients had FDG-positive lesions and 8/45(17.8%) were negative. Median follow-up for longitudinal analysis is 30.1 months. Among initial FDG-negative patients, 7/8 (87.5%) patients remained negative throughout follow-up; 1/8 (12.5%) patients developed a sclerotic FDG-positive lesion deemed not to be progression (rib 5 SUV 1.7). Among the 37 patients with baseline FDG-positive lesions, 12/37(32.4%) patients had complete resolution of FDG-PET-CTs (FDG-responders); 25/37(67.5%) remained FDG-long-term positive at time of last protocol scan. Eight of the 25(32%) FDG-long-term positive patients met IMWG criteria for progression, compared to 0/12 FDG-responders (p value=0.04). For patients with available data, MRD negative status after initial CRd (prior to Len maintenance) was not associated with long-term PET-CT response [19/24(79.2%) vs. 8/11(72.7%), FDG-long-term positive vs. FDG-responders, p=NS]. For the remaining FDG-long-term positive patients not meeting progression criteria, all 17 patients had low-positive persistent FDG with decreased or partial SUV response that decreased over time while on Len maintenance. Conclusions: In patients receiving CRd followed by long-term Len maintenance, 68% of baseline FDG-positive patients have persistent longitudinal FDG-positive myeloma lesions. While there is an increased risk of clinical progression among these patients, the majority showed low-positive FDG lesion uptake that decreased over time with long-term Len maintenance. Long-term resolution of FDG-positive lesions is not associated with MRD status after initial CRd therapy. Further follow-up is needed to examine the significance of persistent FDG-positive lesions in relationship to residual disease and mechanisms of resistance. Figure Figure. Disclosures Korde: Medscape: Honoraria. Hassoun:Takeda: Consultancy, Research Funding; Celgene: Research Funding; Novartis: Consultancy; Binding Site: Research Funding. Landgren:Medscape Myeloma Program: Honoraria; BMS: Honoraria; Merck: Honoraria; Takeda: Honoraria; Amgen: Honoraria, Research Funding; Celgene: Honoraria, Research Funding.

Description: We have treated a total of 30 patients with autologous T cells genetically modified to express a chimeric antigen receptor (CAR) targeting the B-cell antigen CD19; 22 of 27 evaluable patients obtained either complete remissions (CR) or partial remissions (PR). Ten patients remain in ongoing CRs of 1 to 37 months duration. The CAR was encoded by a gammaretroviral vector and included the variable regions of an anti-CD19 antibody along with CD28 and CD3-zeta moieties. The first 21 patients treated on this protocol have been reported (Kochenderfer et al. Blood 2010, Blood 2012, and Journal of Clinical Oncology 2014). To enhance the activity of the transferred CAR T cells, T-cell infusions in the previously reported patients were preceded by a chemotherapy regimen of high-dose cyclophosphamide (60-120 mg/kg) plus fludarabine. In an attempt to reduce the overall toxicity of our anti-CD19 CAR treatment protocol, we substantially reduced the doses of chemotherapy administered before CAR T-cell infusions. This abstract communicates results from 9 patients with B-cell lymphoma who received a single infusion of 1x106 anti-CD19-CAR-expressing T cells/kg bodyweight preceded by a low-dose chemotherapy regimen consisting of cyclophosphamide 300 mg/m2 and fludarabine 30 mg/m2 (Table). Each chemotherapy agent was administered daily for 3 days. Eight of the 9 treated patients had DLBCL (diffuse large B-cell lymphoma) that was refractory to chemotherapy (chemo-refractory) or that had relapsed less than 1 year after autologous stem cell transplantation (ASCT). Both of these clinical situations carry a grim prognosis, with median overall survivals of only a few months. Despite the very poor prognoses of our patients, one patient with DLBCL obtained a CR and 4 DLBCL patients obtained PRs. In some patients, PRs included resolution of large lymphoma masses. Compared to our previous experience with anti-CD19 CAR T cells preceded by high-dose chemotherapy, toxicity was reduced when CAR T cells were infused after low-dose chemotherapy. None of the 9 patients treated with low-dose chemotherapy and CAR T cells required vasopressor drugs or mechanical ventilation, although some patients did have short-term neurological toxicity. Cytopenias were mild with a mean of only 1.4 days of blood neutrophils

Description: Background: With advances in immunotherapeutic approaches and the recognition of antigen modulation as a mechanism of relapse, it is imperative to understand the impact of sequential targeting strategies and the role it may have on outcomes of future therapies to optimize timing of therapeutic interventions. We previously reported on the safety, feasibility, and efficacy on our phase I dose escalation anti-CD22 CAR protocol (clinicaltrials.gov/NCT02315612).1 Based on our initial experience, we identified CD22 loss or diminution of CD22 as a risk factor for relapse following CD22 directed CAR therapy. With development of other CD22 directed therapies, we retrospectively analyzed impact of prior CD22 targeted therapy on response to CD22 CAR in our ongoing clinical trial. Design: Children and young adults with relapsed/refractory CD22+ hematologic malignancies eligible for our phase I dose escalation anti-CD22 CAR protocol were enrolled on study (Clinicaltrials.gov NCT02315612). All had bone marrow evaluations at baseline, prior to lympho-depleting chemotherapy (Fludarabine 25 mg/m2 x 3 days and Cyclophosphamide 900 mg/m2 x 1 day) and again at day 28 (+/- 4 days) post-CAR infusion. We retrospectively analyzed the impact of prior CD22 directed therapy on outcomes following CD22 CAR and specifically looked at the variables of CD22 antigen expression prior to CAR infusion (% positive and antigen density) and compared responses to CD22 CAR for those who did and did not receive prior CD22 targeted therapy. Results: From December 2014 to July 2018, 43 subjects with ALL were treated. All had active bone marrow involvement at baseline, the majority with an M2 marrow (〉5% blasts) or higher disease burden. 34 had a prior transplant and 26 were previously treated with CD19 CAR. Fourteen subjects had received prior CD22 directed therapy, including CD22 CAR elsewhere (n=2) or inotuzumab ozagamicin (Ino) (n=13). Subjects received a median of 3 doses of Ino (3-6 doses) and the median time from last Ino exposure was 2 months (range 1-20 months). Median CD22 antigen expression on bone marrow leukemic blasts prior to planned lymphodepletion for those who had received prior CD22 therapy compared to those who did not was 2527 (882-9079) vs 3929 (846-13452), respectively (one-tailed p=0.05, Figure 1). (Figure 1). Complete remission (CR) rates following CAR-T infusion for those who had prior CD22 directed therapy compared to those who did not was 57% and 71%, respectively with MRD negativity by flow cytometry achieved in only 5/8 (62.5%) patients versus 18/20 (90%) respectively and residual disease in those not achieving MRD negativity was CD22 dim. Both subjects who had received prior CD22 CAR elsewhere were non-responders to our construct with a first-infusion, however one subject converted to a CR with an intensified lymphodepletion and a second infusion. Two subjects who had received prior Ino were noted to have partial CD22 expression on at least one time point (69-89% positivity) prior to enrollment. One of these patients with pre-existing CD22 partial positivity (69% positivity) had evidence for CAR-T cell expansion but had residual low CD22 expressing disease at restaging. Notably, another subject who received 6 doses of Ino prior to receiving CD22 CAR T-cells and had uniformly CD22+ disease at enrollment, emerged with CD22 negative disease following CD22 CAR. Durability of remission also significantly differed amongst the two groups. Median time to relapse in patients who received prior CD22 directed therapy was 2 months (range 2-5 months) versus 6 months (range 2-13 months) for those who did not receive prior CD22 targeted therapy, with the majority relapsing with CD22 negative disease. Conclusion: Sequential targeting of CD19 has anecdotally increased the possibility of CD19 negative relapses, and our data provide evidence for a similar phenomenon with sequential targeting of CD22. Most notably, CD22 expression in patients who had received prior CD22 targeted therapies was lower compared to those who did not. This may have ultimately contributed to both of the observed findings of decreased response rates and decreased durability of remission, the majority of whom relapsed with CD22 negative disease following sequential targeting. This observation contributes to the increasing fund of knowledge regarding optimization of targeted therapies. Disclosures No relevant conflicts of interest to declare.

Description: BACKGROUND: HIV-associated primary central nervous system lymphoma (HIV-PCNSL) is an AIDS-defining cancer. Tumors occur in patients with very low CD4+ counts, and tumors are almost always Epstein-Barr virus (EBV) infected. Overall survival (OS) has improved over time with antiretroviral therapy (ART)-associated immune reconstitution but is still generally less than 1 year. Treatment has traditionally included whole brain radiation, which can lead to devastating long-term neurotoxicity, including cognitive decline. ART has made it possible to treat patients with curative-intent, but radiation-sparing approaches have not been studied prospectively in HIV-PCNSL. METHODS: In a prospective phase II pilot study conducted in the HIV & AIDS Malignancy Branch at the National Cancer Institute, we evaluated curative-intent radiation-sparing immunochemotherapy in patients with untreated HIV-PCNSL (NCT00267865). Patients with HIV-PCNSL received ART, rituximab (375 mg/m2) and HD-MTX (6 g/m2) with leucovorin rescue (R-HD-MTX). Responses were evaluated by modified International Working Group Response Criteria for PCNSL after 6 cycles of induction R-HD-MTX and patients with a complete response (CR) received 2 consolidation cycles of R-HD-MTX. Patients with poor renal or cardiac function who were not eligible to receive HD-MTX at enrollment, received ART, rituximab and best-available radiation-sparing care. The primary objective of the study was to estimate the percentage of patients receiving ART and R-HD-MTX alive without recurrent lymphoma at two years. Response to treatment, immune reconstitution, and OS were evaluated using descriptive statistics and Kaplan-Meier methodology. RESULTS: Twelve patients were enrolled between September 2006 and June 2016. One enrolled patient was initially ineligible to receive HD-MTX due to renal dysfunction and received rituximab with temozolomide (TMZ) 150 mg/m2 for 5 days for one cycle followed by 6 cycles of R-HD-MTX + TMZ and 2 consolidation cycles of R-HD-MTX. Patient characteristics: 9 men, 3 women; median (med) age 33 years (range: 21-55); 8 African-American, 3 Hispanic, 1 white non-Hispanic; med Eastern Cooperative Oncology Group performance status 2 (1-3); med baseline Mini Mental State Examination (MMSE, maximum score = 30) was 22 (range: 5-29). Only 4 patients were on ART prior to diagnosis, and all but 1 had been on ART less than 4 months. Med time from HIV infection to PCNSL diagnosis was 30 weeks (range: 0-23 years). Med CD4+ T-cell count at PCNSL diagnosis was 16 cells/µL (0-409). Diagnosis of PCNSL was biopsy-confirmed (11) or made by 18fludeoxyglucose positron emission tomography/cerebral spinal fluid (CSF) EBV viral load criteria (1). 11/12 tumors were EBV positive. Flow cytometry showed leptomeningeal disease in 4 patients. Three had concurrent CNS infections, including Cryptococcus, histoplasmosis, and CMV retinitis. Ten were evaluable for response to R-HD-MTX induction. Two patients received only 1 cycle of therapy and were not evaluable due to treatment failure (TF). Responses after R-HD-MTX induction: CR (5), partial response (PR) (4) and progressive disease (PD) (1). Two patients with a PR received second-line TMZ at end of R-HD-MTX and obtained a subsequent CR. The patient with PD received second-line therapy with the Cancer and Leukemia Group B 50202 induction regimen and obtained a subsequent CR. There were 4 deaths on study: 1 pulmonary embolism, 1 CNS fungal infection in setting of PD, 2 TF. Eight patients (67%), including 3 patients who received second line therapy, obtained a durable CR. Med CD4+ T-cell increase following R-HD-MTX induction was +35 cells/uL (range: -54 - +369). In surviving patients, med MMSE after R-HD-MTX was 28 (27-30). For all patients, estimated 60-month OS was 66% (95% CI: 32-86%) with med potential follow-up of 82 months. Med OS was not reached. CONCLUSIONS:Treatment with ART and R-HD-MTX is associated with a high response rate, CD4+ immune reconstitution, preserved cognition, and improved OS, even in a high-risk patient population. Disclosures Uldrick: Celgene: Patents & Royalties: 10,001,483 B2; Celgene: Research Funding; Merck: Research Funding. Yarchoan:NIH: Patents & Royalties: Patents on IL-12 for KS and cereblon-binding drugs for KSHV diseases. Spouse has patent on KSHV IL-6. Patents assigned to DHHS/NIH.; Celgene Corp.: Research Funding.

Description: Chronic lymphocytic leukemia (CLL), an incurable malignancy of mature B lymphocytes, involves blood, bone marrow, and secondary lymphoid organs such as the lymph nodes (LN). A role of the tissue microenvironment in the pathogenesis of CLL is hypothesized based on in vitro observations, but its contribution in vivo remains ill-defined. To elucidate the effects of tumor-host interactions in vivo, we purified tumor cells from 24 treatment-naive patients. Samples were obtained concurrently from blood, bone marrow, and/or LN and analyzed by gene expression profiling. We identified the LN as a key site in CLL pathogenesis. CLL cells in the LN showed up-regulation of gene signatures, indicating B-cell receptor (BCR) and nuclear factor-κB activation. Consistent with antigen-dependent BCR signaling and canonical nuclear factor-κB activation, we detected phosphorylation of SYK and IκBα, respectively. Expression of BCR target genes was stronger in clinically more aggressive CLL, indicating more effective BCR signaling in this subtype in vivo. Tumor proliferation, quantified by the expression of the E2F and c-MYC target genes and verified with Ki67 staining by flow cytometry, was highest in the LN and was correlated with clinical disease progression. These data identify the disruption of tumor microenvironment interactions and the inhibition of BCR signaling as promising therapeutic strategies in CLL. This study is registered at http://clinicaltrials.gov as NCT00019370.

Description: Introduction The Bruton’s tyrosine kinase (BTK) inhibitor ibrutinib induces objective clinical responses in the majority of CLL patients (Byrd et al., NEJM 2013). Ibrutinib covalently binds to BTK and with once daily dosing (420 mg, PO) results in 〉 90% inhibition of kinase activity. Germline inactivating mutations in BTK lead to an immunodeficiency syndrome first described by the pediatrician Dr. Bruton in boys suffering from recurrent bacterial infections. These kids, diagnosed with what is now known as Bruton’s agammaglobulinemia, have a severe defect in B cell maturation resulting in the virtual absence of immunoglobulins. Hypogammaglobulinemia is a common complication of CLL and likely is a significant contributor to the increased rate of infections that are a leading cause of death in CLL. Thus, to what degree ibrutinib affects normal B cell function and immunoglobulin levels may in part determine the safety profile of continuous treatment with this agent. Patients and Methods Here we present data from a phase II trial (NCT01500733) of ibrutinib 420 mg daily on 28 day cycles for relapsed/refractory (RR) and treatment naïve (TN) CLL/SLL patients (pts). Serum immune globulins (IgG, IgM, IgA), serum free light chains, and immunofixation electrophoresis were obtained at baseline, and every 6 months thereafter. For statistical analysis of pre-treatment to on-treatment measurements the paired Student t-test was used. Results Here we report on 25 patients (10 TN, 15 RR) who completed 〉12 months on ibrutinib and never received immunoglobulin replacement therapy. By 6 and 12 months, there was a non-statistically significant trend toward decreased IgG levels (ref. range 642-1730) from a pre-treatment median of 601 to 587 mg/dL (at 6 months) and 495 mg/dL (at 12 months; P = 0.14). In contrast, median serum IgA (ref. range 91-499) rose from 42 (baseline) to 58 (at 6 mo) to 61 mg/dL by 12 months (P〈 0.005). Three patients had a clonal IgM on electrophoresis, which decreased with treatment. In the remaining 22 patients IgM (ref. range 34-342) rose from 16 (baseline) to 25 (6 months) to 23 mg/dL by 12 months (P upper limit of normal (median 5.7 mg/dl). At 6 and 12 months there was a 76% and 72% reduction of the KSFLC (P〈 0.01), and in 7 pts the level normalized by 6 months. In contrast, prior to therapy the lambda serum free light chains (LSFLC, ref. range 0.66-2.32 mg/dL) were low (median 0.62 mg/dL) in these patients and increased by 68% (P upper limit of normal (median 8.4 mg/dL), which decreased on ibrutinib by 〉 80% (P〈 0.03) and normalized in 88% of pts by 12 months. The KSFLC in most of these patients was in the low normal range and only increased by 19% from baseline by 12 months. Thus, ibrutinib effectively reduces the clonal light chain, a correlate of tumor control, while the non-clonal light chains, presumably in part reflecting normal B-cells, are low pre-treatment and increase during treatment. Conclusion Consistent with other reports we see little change in IgG levels in the first 12 months. Importantly, ibrutinib leads to a significant increase in both IgA and IgM serum levels, suggesting a beginning recovery of humoral immunity. The reduction of clonal light chains, a tumor marker, correlates with clinical response. In contrast, the increasing levels of the non-clonal light chain may herald a recovery of the normal B-cell (and possibly plasma cell compartment) raising the possibility that ibrutinib may selectively target CLL cells while allowing the re-growth of normal B-cells. We are currently investigating this further. Supported by the Intramural Research Program of NHLBI. We thank our patients for participating and acknowledge Pharmacyclics for providing study drug. Disclosures: Off Label Use: Ibrutinib not FDA approved for CLL.

Description: Inhibition of the B-cell receptor pathway, and specifically of Bruton tyrosine kinase (BTK), is a leading therapeutic strategy in B-cell malignancies, including chronic lymphocytic leukemia (CLL). Target occupancy is a measure of covalent binding to BTK and has been applied as a pharmacodynamic parameter in clinical studies of BTK inhibitors. However, the kinetics of de novo BTK synthesis, which determines occupancy, and the relationship between occupancy, pathway inhibition and clinical outcomes remain undefined. This randomized phase 2 study investigated the safety, efficacy, and pharmacodynamics of a selective BTK inhibitor acalabrutinib at 100 mg twice daily (BID) or 200 mg once daily (QD) in 48 patients with relapsed/refractory or high-risk treatment-naïve CLL. Acalabrutinib was well tolerated and yielded an overall response rate (ORR) of partial response or better of 95.8% (95% confidence interval [CI], 78.9-99.9) and an estimated progression-free survival (PFS) rate at 24 months of 91.5% (95% CI, 70.0-97.8) with BID dosing and an ORR of 79.2% (95% CI, 57.9-92.9) and an estimated PFS rate at 24 months of 87.2% (95% CI, 57.2-96.7) with QD dosing. BTK resynthesis was faster in patients with CLL than in healthy volunteers. BID dosing maintained higher BTK occupancy and achieved more potent pathway inhibition compared with QD dosing. Small increments in occupancy attained by BID dosing relative to QD dosing compounded over time to augment downstream biological effects. The impact of BTK occupancy on long-term clinical outcomes remains to be determined. This trial was registered at www.clinicaltrials.gov as #NCT02337829.

Description: Bortezomib induces remissions in 30%-50% of patients with relapsed mantle cell lymphoma (MCL). Conversely, more than half of patients' tumors are intrinsically resistant to bortezomib. The molecular mechanism of resistance has not been defined. We generated a model of bortezomib-adapted subclones of the MCL cell lines JEKO and HBL2 that were 40- to 80-fold less sensitive to bortezomib than the parental cells. Acquisition of bortezomib resistance was gradual and reversible. Bortezomib-adapted subclones showed increased proteasome activity and tolerated lower proteasome capacity than the parental lines. Using gene expression profiling, we discovered that bortezomib resistance was associated with plasmacytic differentiation, including up-regulation of IRF4 and CD38 and expression of CD138. In contrast to plasma cells, plasmacytic MCL cells did not increase immunoglobulin secretion. Intrinsically bortezomib-resistant MCL cell lines and primary tumor cells from MCL patients with inferior clinical response to bortezomib also expressed plasmacytic features. Knockdown of IRF4 was toxic for the subset of MCL cells with plasmacytic differentiation, but only slightly sensitized cells to bortezomib. We conclude that plasmacytic differentiation in the absence of an increased secretory load can enable cells to withstand the stress of proteasome inhibition. Expression of CD38 and IRF4 could serve as markers of bortezomib resistance in MCL. This study has been registered at http://clinicaltrials.gov as NCT00131976.