ALBERT

Description: Background: Induction chemotherapy for acute myeloid leukemia (AML) is more intensive than many other cancer treatments, and may be associated with a different symptom burden. Little is known about the most prevalent symptoms during AML induction, nor how they change over time, and with remission status. Similarly, little is known about the trajectory of quality of life (QoL) and distress scores in this population. We aimed to learn more about the natural history of these issues via a prospective, longitudinal, observational patient-reported outcomes study. Methods: We enrolled 43 inpatients with AML at initiation of induction chemotherapy, and assessed their symptoms, quality of life (QoL), and distress weekly during their month-long hospitalization for induction, and monthly thereafter, using 3 validated instruments: Patient Care Monitor v2.0 (PCM); Functional Assessment of Cancer Therapy-Leukemia (FACT-Leu); and NCCN distress thermometer (DT). We used descriptive statistics and ANOVA to analyze results. Results: Mean age of study participants was 59.4 (SD 13.4); 21 (49%) were female. Patients were mostly high-risk for recurrence, with 25 (58%) being ≥60 years old, 19 (44%) having high-risk cytogenetics, and 10 (23%) having relapsed disease. Among relapsed patients, the mean number of prior treatments was 2.7 (SD 1.3). At the time of this analysis, 5 patients (18%) had gone on to receive a stem cell transplant. As expected, symptoms were most prominent during the second and third weeks of treatment. However, across all 4 weeks of induction patients consistently reported 5 symptoms at a moderate or severe level (scores of 4 to 6, or 7 to 10 out of 10, respectively), including: poor appetite (35%), dry mouth (37%), difficulty sleeping (38%), dysgeusia (44%), and fatigue (56%). Other prominent moderate-to-severe symptoms included diarrhea (35%), daytime sleepiness (30%), and nausea (27.5%), despite standard supportive care. Mean QoL by FACT-Leu worsened substantially from week 1 (121.8, SD 27.6) to week 2 (108.2, SD 26.3), and then slowly recovered thereafter, improving to better than baseline by month 3 and continuing to improve throughout 1-year of follow-up (p

Description: The IGHV4-34 gene is very frequent (~10%) in the B cell receptor immunoglobulin (BcR IG) gene repertoire of chronic lymphocytic leukemia (CLL). Over 30% of IGHV4-34 CLL cases can be assigned to different subsets with stereotyped BcR IG. The largest is subset #4 which represents ~1% of all CLL and ~10% of IGHV4-34 CLL and is considered a prototype for indolent disease. The BcR IG of a great majority (~85%) of IGHV4-34 CLL cases carry a significant load of somatic hypermutation (SHM), often with distinctive SHM patterns. This holds especially true for stereotyped subsets and is suggestive of particular modes of interactions with the selecting antigen(s). In detail, subsets #4 and #16, both involving IgG-switched cases (IgG-CLL), exhibit the greatest sequence similarity in SHM profiles, whereas they differ in this respect from IgM/D subsets #29 and #201. Prompted by these observations, here we explored the extent that these subset-biased SHM profiles in different IGHV4-34 stereotyped subsets were reflected in distinct demographics, clinical presentation, genomic aberrations and outcomes. Within a multi-institutional series of 20,331 CLL patients, 1790 (8.8%) expressed IGHV4-34 BcR IG. Following established bioinformatics approaches for the identification of BcR IG stereotypy, 573/1790 IGHV4-34 CLL cases (32%) were assigned to stereotyped subsets; of these, 340 cases (19% of all IGHV4-34 CLL and 60% of stereotyped IGHV4-34 cases) belonged to subsets #4, #16, #29 and #201, all concerning IGHV-mutated CLL (M-CLL). Clinicobiological information was available for 275/340 patients: #4, n=150; #16, n=44; #29, n=39; and #201, n=42. Comparisons between subsets revealed no differences in gender and age distribution. Interestingly, however, 36-43% of each subset cases were young for CLL (defined as patients aged ≤55 years), which is higher compared to general CLL cohorts, where young patients generally account for ~25% of cases. In contrast, significant differences were identified between subsets regarding: (i) disease stage at diagnosis, with 〉90% of IgG subsets #4 and #16 diagnosed at Binet stage A versus 83% in subset #201 and 74% in subset #29 (p=0.029); (ii) CD38 expression, ranging from 1% in subset #4 to 10% in subset #201 (p=0.013); (iii) the distribution of del(13q), peaking at a remarkable 92% in subset #29 versus only 37% in subset #16 (p

Description: Background: Nephropathy in sickle cell anemia (SCA) begins in childhood and portends chronic kidney disease, renal failure, and early mortality among affected adults. Individuals of African descent have disproportionately higher rates of developing non-diabetic renal disease. Several candidate genetic variants have been identified, including some specific to African Americans, which are associated with the development of albuminuria and renal disease. The influence of genetic polymorphisms on albuminuria and elevated glomerular filtration rate (GFR) in children with SCA, both early signs of sickle nephropathy, has not been investigated. Objectives: To determine the influence of selected single nucleotide polymorphisms (SNPs) on the development of albuminuria and elevated GFR in children with SCA; to identify novel genetic variants influencing albuminuria and GFR by whole exome sequencing (WES). Design/Methods: Genomic DNA was collected on children with SCA enrolled in two prospective studies with pre-hydroxyurea renal assessments (n=185): (1) Hydroxyurea Study of Long-Term Effects (HUSTLE, NCT00305175, n=79) with no prior disease-modifying therapy; and (2) Transcranial Doppler (TCD) With Transfusions Changing to Hydroxyurea (TWiTCH, NCT 01425307, n=106) on chronic transfusions for abnormal TCD velocities. Albuminuria was defined as ≥30mg albumin/gm creatinine on the pre-hydroxyurea urine specimen. GFR was measured in HUSTLE using plasma DTPA (technetium 99m-labeled diethylenetriaminepentaacetic acid) clearance, and estimated GFR (eGFR) in TWiTCH based on serum creatinine. DNA samples were genotyped for 8 candidate SNPs previously associated with renal disease, using PCR-based allelic discrimination, bidirectional Sanger sequencing, and analysis of variable number tandem repeats (VNTR). Associations between albuminuria and genetic polymorphisms were tested using an additive model and correlation trend test. Linked WES data from the same patients were analyzed to identify other variants associated with albuminuria and GFR. Results: Albuminuria was present in 13.1% of patients, including 16.3% in HUSTLE and 11.0% in TWiTCH. APOL1 genetic variants were common (G1 allele frequency = 21.9%, G2 allele = 16.0%, Table) and similar to published cohorts. Children with two APOL1 G1 alleles had an increased risk of albuminuria that approached statistical significance (p=0.053). Conversely, the presence of the DARC SNP that confers Duffy antigen expression had a protective effect (p=.038). WES analysis did not identify additional non-synonymous APOL1 variants linked with albuminuria. However, 93 non-synonymous variants were associated with DTPA GFR (p

Description: Purpose: We assessed the survival outcome of patients with anaplastic large cell lymphoma (ALCL) who experienced disease progression or relapse after first line and subsequent therapy. We sought to evaluate the impact of brentuximab vedotin (BV), and survival outcome of patients with ALCL who experienced progression after BV. Patients and Methods: A total of 176 patients (74 ALK+, 102 ALK-) initially diagnosed between 1999 and 2014 were retrospectively analyzed. Progression-free survival (PFS) and overall survival (OS) after the progression/relapse following first-line chemotherapy (PFS1 and OS1), after first salvage therapy (PFS2 and OS2) and after second salvage therapy (PFS3 and OS3) were calculated. Outcome was separately analyzed according to the ALK status focusing on the use of BV. Results: The median age of the patients was 50 (range: 18-89). With a median follow up of 64 months, 111 patients (38 ALK+, 73 ALK-) experienced progression/relapse after the first-line therapy, of which 4 ALK- patients were post upfront stem cell transplant (SCT). Thirty and 15 patients eventually underwent autologous and allogeneic SCT after salvage chemotherapy, respectively. The median PFS1 and OS1 in patients with ALK+ALCL and ALK-ALCL were 8.4 and 28.5 months, and 13.1 and 47.7 months, respectively. In patients with ALK+ALCL, the median PFS1, PFS2 and PFS3 were 53.6, 5.2 and 2.3 months, respectively. The median OS1, OS2 and OS3 were not reached, 47.3 and 6.1 months, respectively. In patients with ALK-ALCL, the median PFS1, PFS2 and PFS3 were 12.9, 3.0 and 2.0 months, respectively. The median OS1, OS2 and OS3 were 54.3, 10.8 and 5.8 months, respectively. Interestingly, there were no significant difference in PFS2 between ALK+ALCL and ALK-ALCL. However, OS2 was significantly longer in patients with ALK+ALCL, suggesting possibly continued chemosensitivity of recurrent ALK+ALCL. A total of 30 patients received BV in 1st salvage (15 patients) and after 2nd salvage (15 patients).The use of BV at 1st salvage was associated with significantly longer PFS2 and OS2 both in patients with ALK-ALCL but not with ALK+ALCL likely due to small number of cases. Mutivariate analysis adjusting baseline PIT risk factors and the duration of the response to first line therapy revealed that use of BV (at any point in the salvage setting) is significantly associated with longer OS2 (HR: 0.43, 95%CI: 0.23-0.80). Overall, 12 patients experienced relapse/progression after BV treatment. The median OS after BV failure was 1.4 months (95%CI: 0.5-9.5 months) (Figure). Summary: Survival outcome for relapsed/refractory patients with ALK+ and ALK- patients is improved with BV. However, survival outcome after BV failure is very poor. A new treatment strategies to consolidate or maintain the response after BV and to develop more safe and better therapeutic options are needed. Figure 1. Figure 1. Disclosures Fanale: Merck: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Honoraria, Research Funding; Infinity: Membership on an entity's Board of Directors or advisory committees; Spectrum: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Honoraria, Research Funding; Genentech: Research Funding; Medimmune: Research Funding; Novartis: Research Funding; Bayer: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Molecular Templates: Research Funding; ADC Therapeutics: Research Funding; Onyx: Research Funding; Gilead: Research Funding. Westin:Spectrum: Research Funding. Nastoupil:Celgene: Honoraria; Genentech: Honoraria; AbbVie: Research Funding; Janssen: Research Funding; TG Therapeutics: Research Funding. Wang:Celgene: Research Funding.

Description: Hematopoietic stem cell (HSC) self-renewal in vitro has been reported to result in a diminished proliferative capacity or acquisition of a homing defect that might compromise marrow repopulation. Our group has demonstrated that human HSC expanded ex vivo in the presence of porcine microvascular endothelial cells (PMVEC) retain the capacity to competitively repopulate human bone fragments implanted in severe combined immunodeficiency (SCID) mice. To further test the marrow repopulating capacity of expanded stem cells, our laboratory has established a myeloablative, fractionated total body irradiation conditioning protocol for autologous marrow transplantation in baboons. A control animal, which received no transplant, as well as two animals, which received a suboptimal number of marrow mononuclear cells, died 37, 43, and 59 days postirradiation, respectively. Immunomagnetically selected CD34+ marrow cells from two baboons were placed in PMVEC coculture with exogenous human cytokines. After 10 days of expansion, the grafts represented a 14-fold to 22-fold increase in cell number, a 4-fold to 5-fold expansion of CD34+ cells, a 3-fold to 4-fold increase of colony-forming unit–granulocyte-macrophage (CFU-GM), and a 12-fold to 17-fold increase of cobblestone area-forming cells (CAFC) over input. Both baboons became transfusion independent by day 23 posttransplant and achieved absolute neutrophil count (ANC) 〉500/μL by day 25 ± 1 and platelets 〉20,000/μL by day 29 ± 2. This hematopoietic recovery was delayed in comparison to two animals that received either a graft consisting of freshly isolated, unexpanded CD34+ cells or 175 × 106/kg unfractionated marrow mononuclear cells. Analysis of the proliferative status of cells in PMVEC expansion cultures demonstrated that by 10 days, 99.8% of CD34+ cells present in the cultures had undergone cycling, and that the population of cells expressing a CD34+ CD38− phenotype in the cultures was also the result of active cell division. These data indicate that isolated bone marrow CD34+ cells may undergo cell division during ex vivo expansion in the presence of endothelial cells to provide a graft capable of rescuing a myeloablated autologous host.

Description: Transcranial Doppler (TCD) screening in children with sickle cell anemia (SCA) identifies abnormally elevated cerebral artery flow velocities that confer an elevated risk for primary stroke. Chronic transfusions offer effective stroke prophylaxis in this setting, but must be continued indefinitely and lead to transfusional iron overload. An alternative treatment strategy that offers similar effective protection against primary stroke, and provides control of iron overload, is needed. TCD With Transfusions Changing to Hydroxyurea (TWiTCH, NCT01425307) was an NHLBI-funded Phase III multicenter randomized clinical trial comparing 24-months of standard treatment (transfusions) to alternative treatment (hydroxyurea) in children with SCA and abnormal TCD velocities. All eligible children had received at least 12 months of transfusions. TWiTCH had a non-inferiority trial design; the primary study endpoint was the 24-month TCD velocity obtained from a linear mixed model, controlling for baseline (enrollment) values, with a non-inferiority margin of 15 cm/sec. The transfusion arm maintained children at HbS

Description: Background: A role for the Chemokine (C-C motif) ligand 2 (CCL2) in attracting tumor-associated macrophages (TAMs), myeloid-derived suppressor cells (MDSC) and infiltrating monocytes has been described for many solid tumors in which they play an essential role in modifying the adaptive immune response, ultimately favoring tumor progression. Unfortunately, little is known about the importance of this mechanism for the progression of AML. We recently identified CCL2 as the most prominent chemokine produced by bone marrow (BM) mesenchymal stromal cells (BM-MSC) in response to the interaction with myeloid leukemia cells (PMID: 24599548). In addition, elevated CCL2 plasma levels have been reported in patients of AML (PMID: 17822317), ALL (PMID: 21298741) and CLL (PMID: 22397722) when compared to normal controls. In this study we assessed the effects of blocking the CCR2-CCL2 axis on the migration and signaling of hematopoietic cells as well as on the infiltration of immune-suppressive cells in leukemia-bearing mice. Results: We first studied the efficacy and potency of agents at inhibiting CCL2-mediated migration, using the human monocytic leukemia cell line THP-1. Migration towards human recombinant CCL2 (5 ng/ml) was significantly inhibited by as little as 1 nM of NOX-E36, a human-specific CCL2 Spiegelmer (NOXXON Pharma, Berlin). Spiegelmers are RNA-like molecules built from L-ribose units that are able to bind molecules such as peptides and proteins with an affinity in the pico-to nanomolar range. Similar results were obtained with a CCR2 antagonist (100 ng/ml; Santa Cruz). In anticipation of in vivo studies in mice, we next confirmed the ability of a mouse-specific CCL2 Spiegelmer (mNOX-E36) to inhibit migration and signaling pathway activation in murine hematopoietic cells. For this purpose, we cloned and overexpressed via lentiviral transduction the murine CCL2 receptor (CCR2) in Ba/F3 cells (a murine pro-B cell line). Stimulation of Ba/F3-CCR2 cells with 5 ng/ml of mouse recombinant CCL2 induced a ~2000 fold increase in migration of Ba/F3-CCR2 cells and was successfully blocked with mNOX-E36 in a concentration-dependent manner. Western blot analysis of protein lysates from mCCL2-stimulated cells (30 minutes treatment) indicated activation of AKT, ERK and p38-MAPK. The CCL2-induced phosphorylation of these molecules was completely abrogated by pre-treatment with mNOX-E36. Subsequently, we determined whether the expression of CCL2 by stromal cells in leukemia-resident organs triggers the infiltration of TAMs and possibly other immune-suppressive cells into those organs. We conducted preliminary in vivo studies in non-irradiated immunocompetent C57BL/6 mice (n=5 per group) injected with syngeneic AML1/ETO9a-expressing primary murine leukemia cells (PMID: 19339691). After confirmation of leukemia engraftment by IVIS imaging, mice were treated with mNOX-E36 (14.4 mg/kg, s.c., three times per week) or vehicle control for 3 weeks. At this point, all animals were sacrificed and their tissues (spleens and BM from femurs) were collected for analysis. Although we did not observe differences in leukemia burden by imaging between vehicle and mNOX-E36 treated groups, flow cytometry analysis revealed an increase in the frequency of CD11b+ Ly6Clow MHC IIlow macrophages (2 to 7 fold increase) in spleens of mice engrafted with leukemia (vehicle-treated group) when compared to spleens collected from healthy mice. These MHC IIlow macrophages were previously identified as immunosuppressive M2-like macrophages as opposed to MHC IIhi macrophages which show a pro-inflammatory M1-like phenotype (PMID: 20570887). Importantly, CCL2 inhibitor mNOX-E36 abrogated this macrophage infiltration within the leukemia microenvironment. Conclusions: Our results indicate that blockade of the CCR2-CCL2 axis not only affects migration and signaling of treated cells in vitro, but also interferes with the infiltration of M2-like macrophages into spleens of leukemia-bearing mice. Current in vivo experiments using a combination of standard chemotherapy with mNOX-E36 in AML immunocompetent models are undergoing. We expect that in vivo modulation of CCL2 will improve response to chemotherapy of AML by reducing the marrow infiltration of infiltrating monocytes and tumor-associated macrophages, which would facilitate translation of this novel concept into clinical trials in AML. Disclosures Zuber: Boehringer Ingelheim: Research Funding; Mirimus Inc.: Consultancy, Other: Stock holder. Eulberg:NOXXON Pharma AG: Employment. Kruschinski:NOXXON Pharma AG: Employment.

Description: Background: Fanconi anemia (FA) is caused by mutations in one of seventeen genes that make up the FA DNA double strand break (DSB) repair pathway. Recently, two individuals with biallelic germline BRCA1 mutations, each consisting of one null and one hypomorphic mutation, were identified and noted to have features consistent with FA, including congenital anomalies and increased chromosomal breakage of lymphocytes on exposure to diepoxybutane (Domchek et al. Cancer Discov. 2013 Apr; (4):399-405; and Sawyer et al. Cancer Discov. Epub. 2014 Dec 3.), adding BRCA1 as the newest FA gene. However, neither patient developed bone marrow failure (BMF), making the bone marrow effects of BRCA1 deficiency still unclear. Methods: To test the hypothesis that Brca1 is also essential in hematopoiesis, we developed a conditional mouse model with Mx-1 Cre-mediated Brca1 deletion and examined the effects of Brca1 deficiency on hematopoiesis in this model. Results: At baseline, Brca1-/- mice have macrocytic anemia and leukopenia. Further, by 6 months of age, 30% and 50% of the Brca1-/- mice develop spontaneous BMF or hematologic malignancies (HM), respectively. Brca1-/- mice develop a diverse range of HM, including T-cell lymphomas and acute myeloid leukemias, suggesting a defect in an early hematopoietic progenitor population. Methylcellulose colony forming assays also demonstrate a defect in progenitor cell function with Brca1-/- bone marrow cells forming fewer colonies (44.4±31.9) than Brca1+/+ cells (200.3±30.5, p=0.004) at baseline, and show FA-like hypersensitivity to the DNA cross-linking agent, Mitomycin C (MMC) (mean colony survival % at 10 nM MMC 40% versus 82% and at 50 nM 1% vs 56%). Spectral karyotyping of bone marrow cells from mice that developed BMF demonstrated chromatid exchanges and breaks. Similarly, multiple chromosomal translocations were seen in the myeloid leukemia cells, implicating genomic instability in the pathogenesis of these disorders. Conclusions: Taken together, our results show that loss of Brca1 in murine bone marrow causes hematopoietic defects and MMC sensitivity similar to that seen in humans with FA, providing strong evidence that Brca1 is critical for normal hematopoiesis and that Brca1 is a bona fide FA gene. This novel mouse model provides the opportunity to gain functional insight into the key stage(s) of hematopoiesis that require Brca1 and the effects of Brca1 haploinsufficiency, as seen in humans, on hematopoiesis. Further, as nearly all of the single gene FA mouse models to-date have failed to recapitulate the bone marrow phenotype of human FA, this model will be critical for deepening our understanding of the pathogenesis of FA. Disclosures No relevant conflicts of interest to declare.

Description: Introduction: Use of chimeric Antigen Receptor (CAR) targeting CD19 (CTL019) as a cell-based immunotherapy has been reported to have positive results with high complete response rates in hematological malignancies, including relapsed/refractory (r/r) acute lymphoblastic leukemia (ALL) and non-Hodgkin lymphomas (NHL). In all the studies reported thus far with CTL019, the cell therapy was processed in an academic center (University of Pennsylvania). For large-scale manufacturing of CTL019 and more widespread distribution to patients and physicians, a focus on scalability to meet demands is critical. Here we report the outcomes from successful transfer of CTL019 processing technology from academia to our large-scale GMP facility. Methods & Results: The focus of effective transfer included areas of manufacturing process and analytical technology to consistently manufacture CTL019 with scale-up capabilities. Through strong collaboration of diverse technology transfer team participants from academia, GMP production, Technical development, Quality Assurance and Regulatory, we developed a step-based approach for process transfer. After gathering data from the academia process we made improvements to further enhance control and consistency of the process by implementing key Quality Systems elements (e.g., batch record, change control, process SOPs). Areas of improvement included closing of process steps through customized consumable and equipment solutions; replacing some manual processes with automation solutions and developing a new quantitation method for the expression of the CTL019 transgene. Initial production and release testing results and experience were gained by utilizing healthy donor starting material for manufacturing the cell product in our large scale GMP production facility. Patient-derived autologous CTL019 for treatment of pediatric patients with r/r ALL enrolled in a US-based, multicenter, phase II clinical trial have now been processed in the industry setting. Shipping logistics of the cryopreserved products (apheresis and CTL019) have been established. The cell expansion growth curves and release criteria on the cell products obtained in this large scale manufacturing facility were similar to those obtained at the academic facility. Conclusions: Leveraging a proven step-wise industry transfer process to capture academic experience along with extensive collaborative training and strong analytics led to this successful CAR cell therapy process transfer from academia to industry. This resulted in CTL019 cell expansion growth curves from our process that were similar to those observed from academia, which we anticipate will provide for global scalability. Figure 1. Figure 1. Disclosures Boyd: Novartis Pharmaceuticals Corporation: Employment. Levine:Novartis: Patents & Royalties, Research Funding. Jinivizian:Novartis Pharmaceuticals Corporation: Employment. Jeschke:Novartis Pharmaceuticals Corporation: Employment. Suhoski Davis:Novartis: Patents & Royalties. Zheng:Novartis: Patents & Royalties. Stark:Novartis Pharma AG: Employment. Loidolt:Novartis Pharmaceuticals Corporation: Employment. Keir:Novartis Pharmaceuticals Corporation: Employment. Wood:Novartis Pharmaceuticals Corporation: Employment.

Description: Nonhodgkin lymphomas (NHLs) are among the most common cancer subtypes, with approximately 〉350,000 new cases diagnosed annually worldwide. The majority of NHLs arise from germinal center (GC)-derived B cells. Through network analysis we demonstrated that mutations in focal adhesion pathway genes, including RHOA and GNA13, are a defining characteristic of GC-derived B cell lymphoma, occurring in ~75% of the samples analyzed, and less than 10% of ABC DLBCLs and mantle cell lymphomas. We and others have previously described RHOA mutations in GC-derived B cell lymphomas including DLBCL and Burkitt lymphoma, but the functional consequences of these mutations remain unknown. We examined the patterns of RHOA mutation in DLBCL through targeted gene sequencing in 335 tumor-normal pairs. Cell of origin analysis revealed that there were 128 GCB DLBCLs in this group, with RHOA mutations occurring in 15 (11.7%) of GCB cases and none of the 207 ABC cases. RHOA mutations also occurred in 10% of Burkitt lymphoma cases (total N=66) and zero mantle cell lymphoma cases (total N=54). All the RHOA mutations were missense, and were predicted computationally to be of high impact. A significant proportion of the identified RHOA mutations affect evolutionarily conserved residues within the protein's GTP binding domain, further suggesting a functional importance. Interestingly, inactivating G17V mutations, found in 15% of peripheral T cell and 35-70% of angioimmunoblastic T cell lymphomas, never occurred in DLBCLs. RHOA is thought to signal downstream of GNA13 in a variety of cell types to regulate cellular adhesion and migration. In our study, human mutations in GNA13 and RHOA were mutually exclusive, and GC B cell specific GNA13 deletion in the AID-Cre Gna13 mouse model resulted in reduced levels of active RHOA, suggesting a pathway effect. To determine if the altered migration patterns noted in GNA13 deficient mice were due to loss of RHOA signaling, we crossed RhoA conditional knockout mice with mice expressing Cre under the AID promoter to generate deletion of RhoA exclusively in GC B cells. We then compared these mice with AID-Cre Gna13 knockout mice in parallel experiments. We found that GNA13 deficient mice demonstrate altered GC B migration dynamics, evidence of GC zonal disorganization, and reduced levels of filamentous actin. We also found that GNA13 is required for focal adhesion formation in the human Burkitt lymphoma derived cell line Raji. Similar to the GNA13 deficient state, we found that RHOA deficient GC B cells have altered dark zone and light zone dynamics, with an increased proportion of GC B cells expressing GC light zone markers, and reduced levels of filamentous actin. These data suggest that focal adhesion genes, including RHOA and GNA13, may promote lymphoma in GC B cells via aberrant migration and cellular adhesion, processes normally essential to intrazonal cycling, affinity selection, and GC B cell maturation. To our knowledge, this represents the in vivo characterization of RHOA in GC B cells and RHO mutations in B cell lymphomas and points to an important oncogenic role for RHOA in the germinal center niche. Disclosures No relevant conflicts of interest to declare.