Gouania willdenowi is a teleost fish without immunoglobulin genes.

Immunoglobulin (Ig) genes encode antibodies in jawed vertebrates. They are essential elements of the adaptive immune response. Ig exists in soluble form or as part of the B cell membrane antigen receptor (BCR). Studies of Ig genes in fish genomes reveal the absence of Ig genes in Gouania willdenowi by deletion of the entire Ig locus from the canonical chromosomal region. The genes coding for integral BCR proteins, CD79a and CD79b, are also absent. Genes exist for T α/ß lymphocyte receptors but not for the T γ/δ receptors. The results of the genomic analysis are independently corroborated with RNA-Seq transcriptomes from other Gobiesocidae species. From the transcriptome studies, Ig is also absent from these other Gobiesocidae species, Acyrtus sp. and Tomicodon sp. Present evidence suggests that Ig is missing from all species of the Gobiesocidae family.

Bispecific antibody target pair discovery by high-throughput phenotypic screening using in vitro combinatorial Fab libraries.

Bispecific antibodies can uniquely influence cellular responses, but selecting target combinations for optimal functional activity remains challenging. Here we describe a high-throughput, combinatorial, phenotypic screening approach using a new bispecific antibody target discovery format, allowing screening of hundreds of target combinations. Simple in vitro mixing of Fab-fusion proteins from a diverse library enables the generation of thousands of screen-ready bispecific antibodies for high-throughput, biologically relevant assays. We identified an obligate bispecific co-targeting CD79a/b and CD22 as a potent inhibitor of human B cell activation from a short-term flow cytometry signaling assay. A long-term, high-content imaging assay identified anti-integrin bispecific inhibitors of human cell matrix accumulation targeting integrins ß1 and ß6 or αV and ß1. In all cases, functional activity was conserved from the bispecific screening format to a therapeutically relevant format. We also introduce a broader type of mechanistic screen whereby functional modulation of different cell subsets in peripheral blood mononuclear cells was evaluated simultaneously. We identified bispecific antibodies capable of activating different T cell subsets of potential interest for applications in oncology or infectious disease, as well as bispecifics abrogating T cell activity of potential interest to autoimmune or inflammatory disease. The bispecific target pair discovery technology described herein offers access to new target biology and unique bispecific therapeutic opportunities in diverse disease indications.

Antibody-drug conjugates for previously treated aggressive lymphomas: focus on polatuzumab vedotin.

INTRODUCTION: Antibody-drug conjugates (ADCs) are immunoconjugates and comprise a monoclonal antibody that is chemically attached to a cytotoxic drug (or payload) via a stable chemical linker. Since the approval of the first ADC in 2000, there are now nine different approved agents and over 100 ADCs in the drug-development pipeline. AREAS COVERED: This review briefly describes the ADCs approved for treatment of lymphoma and their distinguishing factors in terms of target, linker and payload. The clinical implications of the use of ADCs are also considered. Here, we focus on polatuzumab vedotin, an ADC targeted to CD79b, which is approved for the treatment of patients with relapsed/refractory diffuse large B-cell lymphoma (R/R DLBCL) who have received at least one (EU approval) or two (US approval) prior therapies and are not eligible for bone marrow transplantation. The characteristics of polatuzumab vedotin are discussed and clinical data are presented. The future of polatuzumab vedotin clinical development, and ADCs in general, are also considered. EXPERT OPINION: ADCs represent a significant advance in the treatment of lymphoma. Polatuzumab vedotin has shown clinical efficacy and a tolerable safety profile in both first-line and R/R DLBCL; future studies are planned to further investigate this ADC.

Asian race and origin have no clinically meaningful effects on polatuzumab vedotin pharmacokinetics in patients with relapsed/refractory B-cell non-Hodgkin lymphoma.

PURPOSE: The CD79b-targeted antibody-drug conjugate polatuzumab vedotin (pola), alone and with chemoimmunotherapy, has clinical efficacy and a tolerable safety profile in B-cell non-Hodgkin lymphoma (B-NHL). We assessed (a) whether exposure from global studies of pola is comparable to Asian patients, and (b) if the recommended pola dose is appropriate in Asian patients based on exposure. METHODS: The pharmacokinetics (PK) of pola in Asian and global populations was characterized for three analytes (antibody-conjugated monomethyl auristatin E (MMAE) [acMMAE], total antibody, and unconjugated MMAE) in five phase 1b/2 single-agent and combination studies in B-NHL patients (JO29138 [JAPICCTI-142580], DCS4968g [NCT01290549], GO27834 [NCT01691898], GO29044 [NCT01992653], and GO29365 [NCT02257567]). PK data were compared between Japanese phase 1 JO29138 (JAPICCTI-142580) and global phase 1 DCS4968g (NCT01290549) studies and between Asian and non-Asian patients in the randomized relapsed/refractory B-NHL cohorts of the phase 1b/2 study GO29365 (NCT02257567). A population PK (popPK) model was used to assess the effects of Asian race and region on acMMAE and unconjugated MMAE exposure. RESULTS: PK non-compartmental analysis (NCA) parameters for the key analyte acMMAE in the Japanese JO29138 (JAPICCTI-142580) and global phase 1 DCS4968g (NCT01290549) studies were similar. In GO29365 (NCT02257567), the phase 1b/2 combination study, mean exposure to the analytes was generally lower in Asian patients (by ~ 9.9 to 17.5%), but not to a clinically meaningful extent. Overall, the popPK model further suggested comparable PK in Asian patients with B-NHL (race or region) versus non-Asian patients. CONCLUSION: Race has no clinically meaningful effect on pola PK. These results (and observations from efficacy/safety exposure-response analyses) support no pola dose adjustments are warranted for Asian patients with DLBCL.

Inflammation Drives MicroRNAs to Limit Hepatocyte Bile Acid Transport in Murine Biliary Atresia.

BACKGROUND: Biliary atresia (BA) is an inflammatory pediatric cholangiopathy with only surgical means for treatment. Many contributors to bile acid synthesis and transport have previously been reported to be downregulated in patients with BA; yet, the driving factors of the abnormal bile acid synthesis and transport in regard to BA have not been previously studied. MATERIALS AND METHODS: Wild type or Ig-α-/- mice were injected with salt solution (control) or rotavirus on day of life 0, and analyses were performed on day of life 14. The mRNA levels of bile acid transporters/nuclear receptors and liver microRNAs (miRNAs) were compared between groups. A mouse hepatocyte cell line was used to examine the effects of innate cytokines on miRNA levels and bile acid transporter/nuclear receptor expression and miRNAs on bile acid transporter/nuclear receptor expression. RESULTS: BA mice had significantly increased mRNA expression of innate cytokines and miRNAs known to bind bile acid transporters/nuclear receptors (miRNAs -22-5p, -34a-5p, and -222-3p) and decreased mRNA expression of bile acid transporters and nuclear receptors. In vitro, TNF-α and IL-1ß decreased BSEP and CYP7A1 while increasing miRNA-34a-5p and miRNA 222-3p. LXR, SHP, CYP7A1, NTCP, and MRP2 were decreased by miRNA-34a-5p, whereas miRNA-222-3p decreased NTCP and MRP4. TNF-α and IL-1ß increased expression of miRNAs 34a-5p and 222-3p and these miRNAs then decrease expression of multiple bile acid transporters and nuclear receptors. CONCLUSIONS: Loss of bile acid transporters increases hepatotoxicity via bile acid retention. Therapeutic agents that increase bile acid transport or nuclear receptor functioning should be investigated in BA.

Polatuzumab vedotin: an investigational anti-CD79b antibody drug conjugate for the treatment of diffuse large B-cell lymphoma.

INTRODUCTION: New agents for managing B-cell non-Hodgkin lymphomas (NHLs) are needed, particularly for high-risk and relapsed or refractory patients. Antibody-drug conjugates (ADCs) provide targeted drug delivery to tumors with a broaden therapeutic index of cytotoxic agent, reducing their systemic toxicity while increasing intracellular concentrations. Polatuzumab vedotin, an anti-CD79b conjugated to the microtubule inhibitor monomethyl auristatin E (MMAE) raises particular interest. AREAS COVERED: We discuss here polatuzumab vedotin development, challenges of designing a successful ADC, preclinical studies and recent trials, leading to FDA approval and the ongoing phase III POLARIX trial. EXPERT OPINION: Clinical data from early studies hold promises for polatuzumab vedotin in association with rituximab-bendamustine in relapsed or refractory (R/R) DLBCL and other combinations are investigated in this setting. In first line, with rituximab, cyclophosphamide, doxorubicin and prednisone (R-CHP), promising results lead to develop the phase III POLARIX trial that may represent a new advance for untreated patients. If dosing and scheduling are adequately managed to avoid peripheral neuropathy risk, polatuzumab vedotin might become a key component of DLBCL therapeutic management. This antibody drug conjugate also offers new opportunities of combination with non-cytotoxic agents or immunological interventions that might reshape the treatment of DLBCL in the future.

Presence of CD3+ and CD79a+ Lymphocytes in the Pituitary Gland of Dogs at Post-mortem Examination.

Hypophysitis has been reported occasionally in dogs, with most cases resembling primary lymphocytic hypophysitis in man. Although it is generally assumed that lymphocytes are not present normally in the canine pituitary gland, few studies have investigated this hypothesis. However, lymphocytes are recognized in the pituitary gland of people and horses without signs of pituitary disease. It is unknown to what degree lymphocyte infiltration of the pituitary gland might occur as an incidental finding in dogs. The aim of the present study was to investigate the presence and distribution of lymphocytes in the pituitary gland of dogs without clinical suspicion of pituitary disease. Twenty dogs were subjected to routine necropsy examination. Formalin-fixed and paraffin wax-embedded sections of pituitary were stained with haematoxylin and eosin (HE) or subjected to immunohistochemistry (IHC) using primary antibodies specific for the T-cell marker CD3 and the B-cell marker CD79a. The number of CD3+ and CD79a+ cells per area unit (CPA) was determined for different pituitary regions. Two dogs had extensive neoplastic lesions in the pituitary gland and were excluded from analysis. In the remaining 18 dogs, occasional scattered CD3+ cells were found in the pituitary gland. There was a significant difference in CD3+ CPA between pituitary regions (P = 0.001). The highest CD3+ CPA was found in the pars tuberalis (median 41.3 cells/mm2, interquartile range 20.9-50.5 cells/mm2). In six of the 18 dogs (33%), CD79a+ cells were detected in small number (median total cell number 0 cells/section, interquartile range 0-1.0 cells/section). This study shows that T cell, and fewer B cells, may be found in the pituitary gland of dogs without clinical suspicion of pituitary disease. Regional difference in T-cell density, with the highest CD3+ CPA in the pars tuberalis, may imply regional immunoregulatory functions in the canine pituitary gland.

Molecular and phenotypic characterization of an early T-cell precursor acute lymphoblastic lymphoma harboring PICALM-MLLT10 fusion with aberrant expression of B-cell antigens.

T-cell acute lymphoblastic leukemia/lymphoma (T-ALL/LBL) is usually diagnosed based on the presence of immature lymphoid marker terminal deoxynucleotidyl transferase (TdT), and T-cell specific markers, specifically CD3, by immunohistochemistry (IHC) staining on bone marrow and/or extramedullary tissue. We present a novel, TdT and CD3 negative, aggressive early T-cell precursor LBL (ETP-LBL) initially misdiagnosed as a high grade B-cell lymphoma due to expression of CD79a and the erroneous detection of BCL2/IGH fusion. The patient was eventually evaluated using molecular diagnostic techniques, including fluorescence in situ hybridization (FISH) and next generation sequencing (NGS) assays that demonstrated PICALM-MLLT10 fusion and a NOTCH1 mutation in the absence of BCL2/IGH fusion. The use of NGS, specifically mate-pair sequencing (MPseq), subsequently confirmed an in-frame PICALM-MLLT10 fusion. Our retrospective analysis showed that PICALM-MLLT10 fusion has no association with CD3/TdT negativity, as 6/49 T-ALL/LBL cases from Mayo Clinic database (01/1998-09/2018), including this case, were noted to have PICALM-MLLT10 fusion; however, none of the other cases were associated with CD3/TdT negativity. We emphasize the importance of a comprehensive hematopathologic evaluation including multiple molecular studies for the appropriate interrogation and classification of a difficult acute leukemia diagnosis, and to prevent potential diagnostic errors of clinical significance.

T cells redirected against Igß for the immunotherapy of B cell lymphoma.

CD19-redirected CAR-T immunotherapy has emerged as a promising strategy for treatment of B cell lymphoma, however, many patients often relapsed due to antigen loss. Therefore, it is urgently needed to explore other suitable antigens targeted by CAR-T cells to cure B cell lymphoma. Igß is a component of the B cell receptor (BCR) complex, which is highly expressed on the surface of lymphoma cells. In this study, we engineered T cells to express anti-Igß CAR with CD28 costimulatory signaling moiety and observed that Igß-CAR T cells could efficiently recognize and eliminate Igß+ lymphoma cells both in vitro and in two different lymphoma xenograft models. The specificity of Igß-CAR T cells was further confirmed through wild type or mutated Igß gene transduction together with Igß-specific knockout in target cells. Of note, both the in vitro and in vivo effect of Igß CAR-T cells was comparable with that of CD19 CAR-T cells. Importantly, Igß CAR-T cells recognized and eradicated patient-derived lymphoma cells in the autologous setting. Lastly, the safety of anti-Igß CAR-T cells could be further enhanced by introduction of the inducible caspase-9 suicide gene system. Collectively, Igß-specific CAR-T cells may be a promising immunotherapeutic approach for B cell lymphoma.

Characterization of CD79αcy+ cells in placentas from ruminants.

Previous work carried out to characterise different immune cells in ruminant placentas found strong CD79αcy nuclear labelling in cells histologically resembling trophoblast cells. In the attempt to characterize this cell population, placentomes collected from cattle, sheep and water buffaloes were examined by immunohistochemistry with single and double labelling using monoclonal antibodies (mAb) against B lymphocytes and trophoblast cells. Most CD79αcy + cells co-expressed placental lactogen or cytokeratin and were CD21 and MHC class II negative strongly suggesting they do not have a B cell origin. However, a potential immunological role of these cells cannot be ruled out and it is currently unknown if the findings described may have an impact on physiological knowledge, health, and or diseases pathogenesis in ruminants.

Chimeric Antigen Receptor T Cells Targeting CD79b Show Efficacy in Lymphoma with or without Cotargeting CD19.

PURPOSE: T cells engineered to express a chimeric antigen receptor (CAR) against CD19 have recently been FDA approved for the treatment of relapsed or refractory large B-cell lymphoma. Despite the success and curative potential of CD19 CAR T cells, several reports describing disease relapse due to antigen loss are now emerging. EXPERIMENTAL DESIGN: We developed a novel CAR construct directed against CD79b, a critical receptor for successful B-cell development that remains highly expressed in several subtypes of B-cell lymphoma, including mantle cell lymphoma (MCL). We tested CAR T cells directed against CD79b alone or in combination with CD19 targeting in a single construct, against cell line- and patient-derived xenograft models. RESULTS: We demonstrate CAR79b antigen-specific recognition and cytotoxicity against a panel of cell lines and patient-derived xenograft models of MCL. Importantly, we show that downregulation of CD19 does not influence surface expression of CD79b and that anti-CD79b CAR T cells alone or arranged in a dual-targeting format with a CD19 single-chain variable fragment (scFv) are able to recognize and eliminate CD19+, CD19-, and mixed CD19+/CD19-B-cell lymphoma. CONCLUSIONS: Our findings demonstrate that CAR T cells targeting CD79b alone or in combination have promise for treating and preventing CD19 antigen escape in B-cell lymphomas.

Evaluation and use of an anti-cynomolgus monkey CD79b surrogate antibody-drug conjugate to enable clinical development of polatuzumab vedotin.

BACKGROUND AND PURPOSE: Polatuzumab vedotin is an antibody-drug conjugate (ADC) being developed for non-Hodgkin's lymphoma. It contains a humanized anti-CD79b IgG1 monoclonal antibody linked to monomethyl auristatin E (MMAE), an anti-mitotic agent. Polatuzumab vedotin binds to human CD79b only. Therefore, a surrogate ADC that binds to cynomolgus monkey CD79b was used to determine CD79b-mediated pharmacological effects in the monkey and to enable first-in-human clinical trials. EXPERIMENTAL APPROACH: Polatuzumab vedotin, the surrogate ADC, and the corresponding antibodies were evaluated in different assays in vitro and in animals. In vitro assessments included binding to peripheral blood mononuclear cells from different species, binding to a human and monkey CD79b-expressing cell line, binding to human Fcγ receptors, and stability in plasma across species. In vivo, ADCs were assessed for anti-tumour activity in mice, pharmacokinetics/pharmacodynamics in monkeys, and toxicity in rats and monkeys. KEY RESULTS: Polatuzumab vedotin and surrogate ADC bind with similar affinity to human and cynomolgus monkey B cells, respectively. Comparable in vitro plasma stability, in vivo anti-tumour activity, and mouse pharmacokinetics were also observed between the surrogate ADC and polatuzumab vedotin. In monkeys, only the surrogate ADC showed B-cell depletion and B-cell-mediated drug disposition, but both ADCs showed similar MMAE-driven myelotoxicity, as expected. CONCLUSIONS AND IMPLICATIONS: The suitability of the surrogate ADC for evaluation of CD79b-dependent pharmacology was demonstrated, and anti-tumour activity, pharmacokinetics/pharmacodynamics, and toxicity data with both ADCs supported the entry of polatuzumab vedotin into clinical trials.

S3Ab, a novel antibody targeting B lymphocytes, is a potential therapeutic agent for B-lineage malignancies.

CD79α protein together with the related CD79ß protein forms the B-cell antigen receptor (BCR). It remains present when B cells transform into active plasma cells, and is also present in virtually all B cell neoplasms. Monoclonal antibody (mAb) S3 (S3Ab) is a novel anti-CD79α antibody generated by using Raji cells as an immunogen. Herein, we conducted a study on S3Ab using various cellular and immunocytological techniques. The results showed that S3Ab could recognise CD79α in living cells. The molecular weights of the heavy and the light chains of S3Ab were 55 and 26 kDa, respectively. S3 antigen is only expressed on more mature B cells and negative on blast B cells. It could partially block the binding of anti-CD79α (Hm47, recognising the cytoplasmic domain of CD79α) to target cells. Immunoprecipitation experiment showed that S3 antigen is about 33 kDa and S3 can specifically bind to the recombinant extracellular segment of CD79α. The internalisation rate of S3Ab to the target cells was as high as 74.0% after incubation at for 3 h. In conclusion, S3Ab is probably a new target molecule for B cells and can be an excellent antibody in targeting treatment of haematopoietic malignancies, warranting further development of this agent.

B cell receptor accessory molecule CD79 gets involved in response against Streptococcus agalactiae infection and BCR signaling in Nile tilapia (Oreochromis niloticus).

CD79, composed of two distinct chains called CD79a and CD79b, is a transmembrane protein that forms a B cell antigen receptor with membrane immunoglobulin, and generates a signal following antigen recognition by the B cell receptor. In this study, the CD79a (OnCD79a) and CD79b (OnCD79b) were cloned and identified from Nile tilapia (Oreochromis niloticus). The cDNA of ORF for OnCD79a and OnCD79b are 669 and 627 bp, coding 222 and 208 amino acids, respectively. The deduced protein analysis showed that both CD79a andCD79b contain an immunoreceptor tyrosine-based activation motif in their intracellular tails that used to propagate a signal in a B cell. Expression analysis revealed that both CD79a and CD79b expressed at high levels in immune tissues, such as anterior kidney and spleen, and in IgM+ B cells. Upon Streptococcus agalactiae (S. agalactiae) infection, the expressions of OnCD79a and OnCD79b were significantly up-regulated in anterior kidney and spleen. The significant up-regulations of OnCD79a and OnCD79b were also detected in leukocytes after in vitro challenge with S. agalactiae. Further, stimulations of LPS and anti-OnIgM monoclonal antibody induced significant up-regulations of OnCD79a and OnCD79b in leukocytes. Taken together, the results of this study indicated that CD79 molecule, playing roles in BCR signaling, was likely to get involved in host defense against bacterial infection in Nile tilapia.

Conditional Selection of B Cells in Mice With an Inducible B Cell Development.

Developing B cells undergo defined maturation steps in the bone marrow and in the spleen. The timing and the factors that control these differentiation steps are not fully understood. By targeting the B cell-restricted mb-1 locus to generate an mb-1 allele that expresses a tamoxifen inducible Cre and another allele in which mb-1 expression can be controlled by Cre, we have established a mouse model with an inducible B cell compartment. With these mice, we studied in detail the kinetics of B cell development and the consequence of BCR activation at a defined B cell maturation stage. Contrary to expectations, transitional 1-B cells exposed to anti-IgM reagents in vivo did not die but instead developed into transitional 2 (T2)-B cells with upregulated Bcl-2 expression. We show, however, that these T2-B cells had an increased dependency on the B cell survival factor B cell activating factor when compared to non-stimulated B cells. Overall, our findings indicate that the inducible mb-1 mouse strain represents a useful model, which allows studying the signals that control the selection of B cells in greater detail.

T Lymphocytes in Histiocytic Sarcomas of Flat-Coated Retriever Dogs.

Flat-Coated Retriever dogs are predisposed to the development of histiocytic sarcoma (HS), a poorly differentiated, highly malignant neoplasm. The authors have previously documented a significant lymphocytic infiltrate in such tumors. The objective of this study was to examine the presence and expression of regulatory T cells in HS tumor samples. Forty tumors were included in this study. All tumors were immunolabeled for CD3, CD79a, CD25, CD45RA, and FOXP3. The proportion of positive cells was compared between tumors presenting as a localized primary soft tissue mass (soft tissue origin HS) and disseminated HS affecting viscera, especially the spleen (splenic origin HS). By immunohistochemistry, 95% of infiltrating T cells were positive for Foxp3 in all sections, suggesting the presence of regulatory T cells. The proportion of cells positive for FOXP3 was higher in the tumors arising in soft tissues, whereas the proportion of CD45RA-positive cells was higher in the splenic origin HS. Canine HS has an aggressive clinical behavior and is uniformly fatal. The difference in the proportion of tumor-infiltrating lymphocytes positive for these 2 markers in the 2 locations may represent differences in tumor microenvironment between the 2 sites.

HISTOPATHOLOGICAL AND IMMUNOHISTOCHEMICAL STUDIES IN EXPERIMENTAL HETEROPHYIASIS AND THE ROLE OF PRAZIQUANTEL AND AMINOGUANIDINE.

Histopathological diagnosis was used to understand the pathological events associated with Heterophyes heterophyes (H. heterophyes) infection. CD3 and CD79α antibodies had been used as markers for both T and. B lymphocytes respectively. Immunohistochemical techniques had several advantages as remarkable sensitivity and specificity. This study aims to evaluate the roles-of praziquantel (PZQ) and aminoguanidine (AG) treatment in H heterophyes infected dogs pathologically and immunohisto-chemically. Study design included experimental infection of dogs with encysted metacercariae of H heterophyes followed by treatment with PZQ and AG. Tissue samples were taken from small intestinal, liver, heart and lung of all groups for histopathological and immunohistochemical studies. Pathological changes were detected in infected tissues by histopathological examination. There was different degree of CD79α+B lymphocytic & CD3+T lymphocytic infiltration detected in immuno-histochemical stained tissues. PZQ caused improvement of pathological changes in the small intestine. However the cellular inflammatory infiltration increased. There was reduction in inflammatory infiltration after intake of AG. Both PZQ and AG improved the pathological changes in the.liver, heart and lung, while the cellular inflammatory infiltration increased after PZQ and reduced by AG. Moreover in the lung AG improves pulmonary congestion and alveolar wall thickness.

Anti-CD22 and anti-CD79b antibody-drug conjugates preferentially target proliferating B cells.

BACKGROUND AND PURPOSE: CD22 and CD79b are cell-surface receptors expressed on B-cell-derived malignancies such as non-Hodgkin's lymphoma (NHL). An anti-mitotic agent, monomethyl auristatin E, was conjugated to anti-CD22 and anti-CD79b antibodies to develop target-specific therapies for NHL. The mechanism of action (MOA) and pharmacological and pharmacokinetic (PK) profiles of these antibody-drug conjugates (ADCs) were investigated in cynomolgus monkeys. EXPERIMENTAL APPROACH: Animals were administered anti-CD22 or anti-CD79b ADCs, respective unconjugated antibodies or vehicle. Pharmacodynamic effects on total and proliferating B cells and serum PK were then assessed. Antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) of the ADCs were evaluated in vitro. KEY RESULTS: Depletion of B cells was observed after administration of either ADC or the respective unconjugated antibodies. An extended duration of depletion was observed in animals administered ADCs. Similarly, preferential depletion of proliferating B cells in blood and germinal centre B cells in spleen were only observed in animals administered ADCs. Serum PK profiles of ADCs and respective unconjugated antibodies were comparable. In vitro, anti-human CD22 and anti-human CD79b antibodies showed no or only moderate ADCC activity, respectively; neither antibody had CDC activity. CONCLUSIONS AND IMPLICATIONS: The findings support the proposed MOA: initial depletion of total B cells by antibody-mediated opsonization, followed by preferential, sustained depletion of proliferating B cells by the auristatin conjugate due to its anti-mitotic action. Delivering potent anti-mitotic agents to B cells via the specificity of monoclonal antibodies provides a means to eliminate pathogenic B cells in NHL with improved risk-benefit profiles over traditional chemotherapeutics.

IL-4 rescues surface IgM expression in chronic lymphocytic leukemia.

Chronic lymphocytic leukemia (CLL) cells express poor levels of surface immunoglobulin (sIg), and many are minimally activated or anergic in response to B-cell receptor (BCR) crosslinking in vitro. Paradoxically, CLL cells in patients are highly activated through BCR signaling and expand in proliferation centers, suggesting that the function of sIg signaling is rescued. Here, we find that, compared with normal naïve B cells, CLL cells express a low level of total CD79b protein but normal levels of CD79a and IgM protein. Association of both CD79a and CD79b to IgM is markedly reduced. We further find that interleukin-4 (IL-4) markedly rescues CD79b and sIgM protein in CLL samples. These changes significantly enhance signaling in response to BCR crosslinking. Furthermore, we find that these changes are more pronounced in immunoglobulin heavy chain variable (IGHV)-unmutated CLL cells than IGHV-mutated CLL cells. The results described herein reveal that reduced sIgM is due to low expression of total CD79b protein in CLL cells. IL-4 substantially restores CD79b protein expression, sIgM expression, and BCR signaling.

A review of monoclonal antibody therapies in lymphoma.

Monoclonal antibodies (moAb) represent a novel way of delivering therapy through specific target antigens expressed on lymphoma cells and minimizes the collateral damage that is common with conventional chemotherapy. The paradigm of this approach is the targeting of CD20 by rituximab. Since its FDA approval in 1997, rituximab has become the standard of care in almost every line of therapy in most B-cell lymphomas. This review will briefly highlight some of the key rituximab trials while looking more closely at the evidence that is bringing other antibodies, including next generation anti-CD20 moAbs, and anti-CD30 moAbs, among others to the forefront of lymphoma therapy.