Immune Reconstitution and Vaccinations in Multiple Myeloma: A Report From the 19th International Myeloma Society Annual Workshop.

Given the significance of the immune system and the important role of therapies within the context of the immune system in plasma cell disorders, the International Myeloma Society annual workshop convened a session dedicated to this topic. A panel of experts covered various aspects of immune reconstitution and vaccination. The top oral presentations were highlighted and discussed. This is a report of the proceedings.

Fully synthetic platform to rapidly generate tetravalent bispecific nanobody-based immunoglobulins.

Nanobodies bind a target antigen with a kinetic profile similar to a conventional antibody, but exist as a single heavy chain domain that can be readily multimerized to engage antigen via multiple interactions. Presently, most nanobodies are produced by immunizing camelids; however, platforms for animal-free production are growing in popularity. Here, we describe the development of a fully synthetic nanobody library based on an engineered human VH3-23 variable gene and a multispecific antibody-like format designed for biparatopic target engagement. To validate our library, we selected nanobodies against the SARS-CoV-2 receptor-binding domain and employed an on-yeast epitope binning strategy to rapidly map the specificities of the selected nanobodies. We then generated antibody-like molecules by replacing the VH and VL domains of a conventional antibody with two different nanobodies, designed as a molecular clamp to engage the receptor-binding domain biparatopically. The resulting bispecific tetra-nanobody immunoglobulins neutralized diverse SARS-CoV-2 variants with potencies similar to antibodies isolated from convalescent donors. Subsequent biochemical analyses confirmed the accuracy of the on-yeast epitope binning and structures of both individual nanobodies, and a tetra-nanobody immunoglobulin revealed that the intended mode of interaction had been achieved. This overall workflow is applicable to nearly any protein target and provides a blueprint for a modular workflow for the development of multispecific molecules.

A neutralizing bispecific single-chain antibody against SARS-CoV-2 Omicron variant produced based on CR3022.

Introduction: The constantly mutating SARS-CoV-2 has been infected an increasing number of people, hence the safe and efficacious treatment are urgently needed to combat the COVID-19 pandemic. Currently, neutralizing antibodies (Nabs), targeting the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein are potentially effective therapeutics against COVID-19. As a new form of antibody, bispecific single chain antibodies (BscAbs) can be easily expressed in E. coli and exhibits broad-spectrum antiviral activity. Methods: In this study, we constructed two BscAbs 16-29, 16-3022 and three single chain variable fragments (scFv) S1-16, S2-29 and S3022 as a comparison to explore their antiviral activity against SARS-CoV-2. The affinity of the five antibodies was characterized by ELISA and SPR and the neutralizing activity of them was analyzed using pseudovirus or authentic virus neutralization assay. Bioinformatics and competitive ELISA methods were used to identify different epitopes on RBD. Results: Our results revealed the potent neutralizing activity of two BscAbs 16-29 and 16-3022 against SARS-CoV-2 original strain and Omicron variant infection. In addition, we also found that SARS-CoV RBD-targeted scFv S3022 could play a synergistic role with other SARS-CoV-2 RBD-targeted antibodies to enhance neutralizing activity in the form of a BscAb or in cocktail therapies. Discussion: This innovative approach offers a promising avenue for the development of subsequent antibody therapies against SARSCoV-2. Combining the advantages of cocktails and single-molecule strategies, BscAb therapy has the potential to be developed as an effective immunotherapeutic for clinical use to mitigate the ongoing pandemic.

Preclinical evaluation of ISH0339, a tetravalent broadly neutralizing bispecific antibody against SARS-CoV-2 with long-term protection.

BACKGROUND: Ending the global COVID-19 pandemic requires efficacious therapies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Nevertheless, the emerging Omicron sublineages largely escaped the neutralization of current authorized monoclonal antibody therapies. Here we report a tetravalent bispecific antibody ISH0339, as a potential candidate for long-term and broad protection against COVID-19. METHODS: We report here the making of ISH0339, a novel tetravalent bispecific antibody composed of a pair of non-competing neutralizing antibodies that binds specifically to two different neutralizing epitopes of SARS-CoV-2 receptor-binding domain (RBD) and contains an engineered Fc region for prolonged antibody half-life. We describe the preclinical characterization of ISH0339 and discuss its potential as a novel agent for both prophylactic and therapeutic purposes against SARS-CoV-2 infection. RESULTS: ISH0339 bound to SARS-CoV-2 RBD specifically with high affinity and potently blocked the binding of RBD to the host receptor hACE2. ISH0339 demonstrated greater binding, blocking and neutralizing efficiency than its parental monoclonal antibodies, and retained neutralizing ability to all tested SARS-CoV-2 variants of concern. Single dosing of ISH0339 showed potent neutralizing activity for treatment via intravenous injection and for prophylaxis via nasal spray. Preclinical studies following single dosing of ISH0339 showed favorable pharmacokinetics and well-tolerated toxicology profile. CONCLUSION: ISH0339 has demonstrated a favorable safety profile and potent anti-SARS-CoV-2 activities against all current variants of concern. Furthermore, prophylactic and therapeutic application of ISH0339 significantly reduced the viral titer in lungs. Investigational New Drug studies to evaluate the safety, tolerability and preliminary efficacy of ISH0339 for both prophylactic and therapeutic purposes against SARS-CoV-2 infection have been filed.

Evolution of Clinical Trials in Oncohematology in a Reference Center: Does It Worth a Dedicated Structure?

Introduction: As part of the reorganization of our outpatient activity in onco-hematology (OH), questions were raised about the relevance of dedicating a specific structure to clinical research in this field. These questions arise all the more so as the proportion of OH clinical trials (CT) in our center has increased from 10% to 45% of all CT between 2000 and 2020. The aim of this study is to assess the evolution of this activity and thus to consider the interest of such a structure. Material(s) and Method(s): A retrospective data review of new CT related to OH in our center from 2016 to 2021 was performed. The evolution of 3 key indicators was assessed: distribution of OH CT among all CT, main OH indications and preferred routes of administration. Results and discussion: Over the period 2016-2021, OH CT represented an average of 32% of newly activated CT corresponding to 34% in 2016 and 48% in 2021 (approximately 90 CT start each year for a total of 420 CT in our center). A short decrease was observed in 2019 and 2020, 25% and 24% respectively, probably related to Covid-19. In terms of sterile preparations, OH represented steadily more than 60% of our activity over the period. The main indications were lymphomas (30%), acute myeloid leukemias (AML - 19%), myelodysplastic syndromes (12%) and CT related to transplant center (12%) in steady distribution overtime. Only new CT in myeloma increased from 7% to 18% in relation with increased subcutaneous (SC) use of daratumumab. Regarding preferred routes of administration, an increased trend in oral and SC routes is observed (respectively 53% and 7% in 2016 vs. 69%and 28% in 2021). The increasing use of SC intensified in 2017 as part of the arrival of AML treatments combining azacitidine (SC) with venetoclax (oral). New CT using the intravenous route decreased from 70% in 2016 to 51% in 2021 even if bispecific antibodies araised in 2021. Focusing in 2021, 1359 visits (772 in day hospital for protocol chemotherapy and 597 for oral treatment) were observed, i.e. 6 patients per day. Conclusion(s): This review showed OH's activity growth in our center. The increasingly frequent use of SC and oral routes requires that patients be fully informed and trained about their own management. In this context, a pharmacist has its place and could best inform patients about the adverse effects of new complex therapies (antibodies, targeted therapy). A unique place, organized and dedicated to clinical research in OH, would allow patients benefiting from a structured and exhaustive support as well as meeting all the healthcare professionals involved and finally ensuring the conditions for optimal care.

Novel bispecific human antibody platform specifically targeting a fully open spike conformation potently neutralizes multiple SARS-CoV-2 variants.

Rapid emergence of new variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has prompted an urgent need for the development of broadly applicable and potently neutralizing antibody platform against the SARS-CoV-2, which can be used for combatting the coronavirus disease 2019 (COVID-19). In this study, based on a noncompeting pair of phage display-derived human monoclonal antibodies (mAbs) specific to the receptor-binding domain (RBD) of SARS-CoV-2 isolated from human synthetic antibody library, we generated K202.B, a novel engineered bispecific antibody with an immunoglobulin G4-single-chain variable fragment design, with sub- or low nanomolar antigen-binding avidity. Compared with the parental mAbs or mAb cocktail, the K202.B antibody showed superior neutralizing potential against a variety of SARS-CoV-2 variants in vitro. Furthermore, structural analysis of bispecific antibody-antigen complexes using cryo-electron microscopy revealed the mode of action of K202.B complexed with a fully open three-RBD-up conformation of SARS-CoV-2 trimeric spike proteins by simultaneously interconnecting two independent epitopes of the SARS-CoV-2 RBD via inter-protomer interactions. Intravenous monotherapy using K202.B exhibited potent neutralizing activity in SARS-CoV-2 wild-type- and B.1.617.2 variant-infected mouse models, without significant toxicity in vivo. The results indicate that this novel approach of development of immunoglobulin G4-based bispecific antibody from an established human recombinant antibody library is likely to be an effective strategy for the rapid development of bispecific antibodies, and timely management against fast-evolving SARS-CoV-2 variants.

Targeted Treatment of Relapsed or Refractory Follicular Lymphoma: Focus on the Therapeutic Potential of Mosunetuzumab.

Follicular lymphoma is the most common indolent non-Hodgkin's lymphoma, and because of the incurable nature of this disorder, new therapies are constantly needed. The recently approved T-cell-dependent bispecific antibody mosunetuzumab showed promising results and manageable toxicities for patients with relapsed or refractory follicular lymphoma. Namely, as opposed to cellular immunotherapy options, this agent has the potential of being effective in patients with unfavorable features with a tolerable rate and severity of cytokine release syndrome, immune effector cell-associated neurotoxicity, and infectious complications. Given the recent withdrawal from the market of PI3K inhibitors and the practical challenges in utilizing with chimeric antigen receptor T-cells (CAR-T) for some patients, mosunetuzumab represents a "breath of fresh air" for both patients and hemato-oncologists. More data are required to better define the real potential of this molecule, either alone or in combination with other agents, including antibody drug conjugates, immunomodulators, and checkpoint inhibitors. Future studies will also shed light on the efficacy of mosunetuzumab compared with CAR-T, in well-designed registries or ideally in randomized controlled trials.

Bispecific antibodies and its applications: a novel approach for targeting SARS-Cov-2.

The COVID-19 pandemic remains a severe global threat, with the world engulfed in the struggle against the disease's second or third waves, which are approaching frightening proportions in terms of cases and mortality in many nations. Despite the critical need for effective therapy, there is still uncertainty about the optimal practices for treating COVID-19 with various pharmaceutical approaches. This being third year, global immunity and eradication of SARS-CoV-2 is currently seems to be out of reach. Efforts to produce safe and effective vaccinations have shown promise, and progress is being made. Additional therapeutic modalities, as well as vaccine testing in children, are required for prophylaxis and treatment of high-risk individuals. As a result, neutralising antibodies and other comparable therapeutic options offer a lot of promise as immediate and direct antiviral medications. Bispecific antibodies offer a lot of potential in COVID-19 treatment because of their qualities including stability, small size and ease of manufacture. These can be used to control the virus's infection of the lungs because they are available in an inhalational form. To combat the COVID-19 pandemic, innovative approaches with effective nanobodies, high-expression yield and acceptable costs may be required.

Antibodies as drugs-a Keystone Symposia report.

Therapeutic antibodies have broad indications across diverse disease states, such as oncology, autoimmune diseases, and infectious diseases. New research continues to identify antibodies with therapeutic potential as well as methods to improve upon endogenous antibodies and to design antibodies de novo. On April 27-30, 2022, experts in antibody research across academia and industry met for the Keystone symposium "Antibodies as Drugs" to present the state-of-the-art in antibody therapeutics, repertoires and deep learning, bispecific antibodies, and engineering.

Comparative Assessment of the Binding and Neutralisation Activity of Bispecific Antibodies Against SARS-CoV-2 Variants.

Background: Neutralising antibodies against SARS-CoV-2 are a vital component in the fight against COVID-19 pandemic, having the potential of both therapeutic and prophylactic applications. Bispecific antibodies (BsAbs) against SARS-CoV-2 are particularly promising, given their ability to bind simultaneously to two distinct sites of the receptor-binding domain (RBD) of the viral spike protein. Such antibodies are complex molecules associated with multi-faceted mechanisms of action that require appropriate bioassays to ensure product quality and manufacturing consistency. Methods: We developed procedures for biolayer interferometry (BLI) and a cell-based virus neutralisation assay, the focus reduction neutralisation test (FRNT). Using both assays, we tested a panel of five BsAbs against different spike variants (Ancestral, Delta and Omicron) to evaluate the use of these analytical methods in assessing binding and neutralisation activities of anti-SARS-CoV-2 therapeutics. Results: We found comparable trends between BLI-derived binding affinity and FRNT-based virus neutralisation activity. Antibodies that displayed high binding affinity against a variant were often followed by potent neutralisation at lower concentrations, whereas those with low binding affinity also demonstrated reduced neutralisation activity. Conclusion: The results support the utility of BLI and FRNT assays in measuring variant-specific binding and virus neutralisation activity of anti-SARS-CoV-2 antibodies.

ANTICORPII MONOCLONALI ȘI UTILIZAREA ACESTORA ÎN TERAPIA ȘI IMUNOPROFILAXIA INFECȚIILOR VIRALE - ACTUALITĂȚI ȘI PERSPECTIVE

Anticorpii joacă un rol esenţial în imunitatea antiinfecţioasă, fiind principalele biomolecule instrumentale pentru prevenirea sau modularea specifică a infecţiilor virale. Obiective. Studiul de faţă a urmărit actualizarea informaţiilor ştiinţifice privind anticorpii cu potenţial imunoprofilactic şi terapeutic în viroze de importanţă majoră pentru sănătatea publică (rabie, arboviroze, COVID-19, gripa cu tulpini înalt patogene), precum şi tehnologiile contemporane de obţinere a anticorpilor în laborator, pentru a fitestaţi şi utilizaţi în clinică. Materiale şi metode. Au fost studiate datele din literatura ştiinţifică de specialitate publicate în ultimii 10 ani, cu deosebire cele cu impact ştiinţific şi profesional de excelenţă (grupurile editoriale Nature, Science, Lancet, Elsevier, MDPI etc). Informaţiile au fost filtrate prin experienţa practică de lucru în domeniu a autorului, la nivel naţional şi internaţional. Rezultate şi discuţii. În prezent, pentru a genera anticorpi monoclonali, există o paletă largă de tehnologii care se utilizează în laborator: a) fuzionarea limfocitelor B cu linii de celule de mielom uman sau uman/murin;b) imortalizarea limfocitelor B prin transformare cu virusul Epstein-Barr;c) tehnologia denumită phage display care implică exprimarea regiunilor variabile (VH şi VL) ale imunoglobulinei G pe suprafaţa unor bacteriofagi, care sunt apoi selectaţi iterativ prin legarea la un antigen specific;d) tehnicile de clonare celulară prin sortarea celulelor B de memorie specifice pentru un antigen, cultivarea acestor in vitro cu activare antigen specifică, urmată de amplificarea genică şi clonarea regiunilor variabile ale lanţurilor grele şi uşoare, pornind de la o singură celulă B;ulterior regiunile clonate se exprimă în vectori specifici de expresie proteică. e) tehnologii bazate pe ADN şi ARN mesager. Pe de altă parte, se pot obţine in vitro anticorpi monoclonali, himerici, bispecifici, fragmente de anticorpi, cu proprietăţi funcţionale şi farmacologice particulare. Până la sfarşitul anului 2021 existau aproximativ 100 de tipuri de anticorpi aprobaţi pentru utilizări în clinica infecţiilor virale, la nivel mondial. Concluzii. Îmbunătăţirea şi apariţia noi abordări ale tehnologiilor de clonare celulară şi moleculară, precum şi industrializarea proceselor în condiţii automatizate, conduc la posibilitatea de a dezvolta anticorpi monoclonali cu înaltă eficienţă şi scurtarea considerabilă a timpului necesar de control şi evaluare a acestora pentru înregistrarea punerii pe piaţă. Utilizarea anticorpilor neutralizanţi rămâne una dintre cele mai promiţătoare opţiuni în lupta împotriva infecţiilor virale, fiind o decizie strategică în contextul apariţiei de noi epidemii sau al ameninţărilor bioteroriste. Sursa de finanţare: lucrări desfăşurate în cadrul proiectului PSCD/2022 - VIROMAB H, finanţat de Ministerul Apărării Naţionale.Alternate :Antibodies play an essential role in anti-infective immunity, being the main instrumental biomolecules for the specific prevention or modulation of viral infections. Objectives. The present study aimed to update scientific information regarding antibodies with immunoprophylactic and therapeutic potential in viroses of major importance for public health (rabies, arboviruses, COVID-19, influenza with highly pathogenic strains), as well as contemporary technologies for getting antibodies in the laboratory, in order to be tested and used in the clinic. Materials and methods. Data from specialized scientific literature published in the last 10 years were studied, especially those publications with excellent scientific and professional impact (publishing groups Nature, Science, Lancet, Elsevier, MDPI etc.). The information has been filtered through the author's practical work experience in the field, at national and international level. Results and discussion. Currently, to generate monoclonal antibodies, there is a wide range of te hnologies that are used in the laboratory: a) fusion of B lymphocytes with human or human/murine myeloma cell lines;b) immortalization of B lymphocytes by transformation with the Epstein-Barr virus;c) the phage display technology that involves the expression of the variable regions (VH and VL) of immunoglobulin G on the surface of some bacteriophages, which are then iteratively selected by binding to a specific antigen;d) cell cloning techniques by sorting memory B cells specific for an antigen, in vitro cell cultivation with specific antigen activation, followed by gene amplification and cloning of the variable regions of the heavy and light chains (VH, VL) starting from a single B cell;subsequently the cloned regions are expressed in specific vectors. e) technologies based on DNA and messenger RNA. On the other hand, monoclonal, chimeric, bispecific antibodies, antibody fragments can be obtained in vitro, with particular functional and pharmacological properties. By the end of 2021 there were approximately 100 types of antibodies approved for use in the clinic of viral infections, worldwide. Conclusions. The improvement and the emergence of new approaches to cellular and molecular cloning technologies, as well as the industrialization of processes under automated conditions, lead to the possibility of developing monoclonal antibodies with high efficiency and the considerable shortening of the time required for their control and evaluation for market registration. The use of neutralizing antibodies remains one of the most promising options in the fight against viral infections, being a strategic decision in the context of the emergence of new epidemics or bioterrorist threats. Funding source: works carried out within the project PSCD/2022 - VIROMAB H, funded by the Ministry of National Defense.

An Engineered IgG-VHH Bispecific Antibody against SARS-CoV-2 and Its Variants.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) neutralizing antibodies are shown to be effective therapeutics for providing coronavirus disease 2019 (COVID-19) protection. However, recurrent variants arise and facilitate significant escape from current antibody therapeutics. Bispecific antibodies (bsAbs) represent a unique platform to increase antibody breadth and to reduce neutralization escape. Herein, a novel immunoglobulin G-variable domains of heavy-chain-only antibody (IgG-VHH) format bsAb derived from a potent human antibody R15-F7 and a humanized nanobody P14-F8-35 are rationally engineered. The resulting bsAb SYZJ001 efficiently neutralizes wild-type SARS-CoV-2 as well as the alpha, beta, gamma, and delta variants, with superior efficacy to its parental antibodies. Cryo-electron microscopy structural analysis reveals that R15-F7 and P14-F8-35 bind to nonoverlapping epitopes within the RBD and sterically hindered ACE2 receptor binding. Most importantly, SYZJ001 shows potent prophylactic and therapeutic efficacy against SARS-CoV-2 in three established mouse models. Collectively, the current results demonstrate that the novel bsAb format is feasible and effective, suggesting great potential as an inspiring antiviral strategy.

Human monoclonal antibodies to the spike subdomain 1 neutralize SARS-CoV-2 and its variants of concern

Progress in the fight against COVID-19 is jeopardized by the emergence of SARS-CoV-2 variants that diminish or abolish the efficacy of vaccines and antiviral monoclonal antibodies. Novel immune therapies are therefore needed, that are broadly effective against present and future coronavirus threats. In principle, this could be achieved by focusing on portions of the virus that are both functionally relevant and averse to change. The Subdomain 1 (SD1) of SARS-CoV-2 Spike protein is adjacent to the RBD and its sequence is conserved across SARS-CoV-2 variants, except for substitutions A570D in Alpha (B.1.1.7) and T547K in Omicron BA.1 (B.1.1.529). In order to specifically identify and study human antibodies targeting SD1, we designed a flow cytometry-based strategy that combines negative selection of B cells binding to the Receptor Binding Domain (RBD) with positive selection of those binding to SD1-RBD fusion protein. Among the 15 produced human monoclonal antibodies, 6 are SD1-specific. 3 of them cross-react with SD1-RBDs corresponding to all six variants of concern and 2 are neutralizing SARS-CoV-2 pseudovirus. Antibody sd1.040 also neutralizes Delta, Omicron BA.1 and Omicron BA.2 pseudovirus, synergizes with an antibody to the RBD for neutralization, and protects mice when present in a bispecific antibody. Thus, naturally occurring antibodies can neutralize SARS-CoV-2 variants by binding to SD1 and can act synergistically against SARS-CoV-2 in preclinical models.

MANAGEMENT OF RELAPSED / REFRACTORY (R/R) B-CELL NON HODGKIN LYMPHOMA (B-NHL) WITH ANTI-CD20XCD3 BISPECIFIC ANTIBODY GLOFITAMAB. A SINGLE CENTER EXPERIENCE

Background: Prognosis of r/r B-NHL is detrimental. Potentially curative therapeutic approaches, such as autologous stem cell transplantation and innovative CAR-T cell therapy, require maximum disease control to achieve optimal results. Glofitamab is a new bispecific antibody, with a unique 2:1 molecular configuration resulting in superior potency compared with other CD20xCD3 bispecific antibodies with a 1:1 format. Aims: Based on these encouraging results, we included 5 heavily pretreated patients in the early access program of Glofitamab, available in our country. Methods: We collected the data of 5 consecutive patients with r/r B-NHL, who were treated with Glofitamab in our department during the last 15 months. Results: Three men and 2 women, median age of 57 years (38-62), were resistant to 4 (n = 3) and 5 (n = 2) previous lines of treatment. The underlying lymphoma was Richter's transformation of CLL after allogeneic transplantation (alloHSCT), transformed follicular lymphoma (tFL), primary mediastinal B-cell lymphoma (PMBCL), r/r diffuse large B-cell lymphoma (DLBCL) after CAR-T therapy and gray zone lymphoma (GZL) transformed to DLBCL. The median number of Glofitamab cycles administered was 3 (2-7). All 5 patients responded early to treatment, which became apparent immediately after the first dose of 2.5 mg. The patient with Richter's syndrome achieved metabolic remission after the 4th cycle and underwent second alloHSCT after the 7th cycle. Unfortunately, he passed away 8 months after alloHSCT due to disseminated atypical mycobacterial infection, remaining however disease free. The patient with tFL also achieved metabolic remission, but the drug was discontinued after the 7th cycle due to COVID-19 infection. He died two months after Glofitamab interruption due to disease progression and CMV encephalitis. The patient with PMBCL, responded partially after Glofitamab and had mediastinal radiotherapy as bridging therapy to CAR-T therapy. As the latter was delayed due to CMV reactivation and CMV enteritis, our patient deceased due to progressive disease. The patient with DLBCL after CAR-T therapy had initial clinical response after two Glofitamab cycles. Due to severe COVID-19, we decided to hold Glofitamab. COVID-19 and disease progression led to his death, a few weeks after COVID-19 diagnosis. Finally, the patient with transformed GZL had Glofitamab administered as bridging therapy prior to CAR-T treatment. After 3 cycles, while she was prepared to proceed to CAR-T therapy, she was diagnosed with invasive aspergillosis. She is currently been treated with antifungal agents, whereas disease is still active. Cytokine release syndrome (CRS) occurred in 3 out of 5 patients. In all cases it was grade 1-2 and manifested at the first administration of the drug, after 4, 32 and 10 hours respectively, from infusion initiation. CRS was managed with antipyretics and steroids, whereas none patient required Intensive Care Unit support. Only one patient required tocilizumab. No Immune effector cell-Associated Neurotoxicity Syndrome (ICANS) was observed. Summary/Conclusion: Glofitamab is effective in treating patients with r/r aggressive B-cell NHL. Efficacy makes it an appropriate bridging tool to autologous, alloHSCT or CAR-T therapy. Nevertheless, relapse remains a challenge for r/r disease. Adverse events, such as CRS, were generally manageable. Given the fact that it was administered to heavily pretreated patients, caution to opportunistic pathogens should be paid. Indeed, toxicity profile may be proven to be more favorable if the agent is being administered earlier in therapeutic algorithms.

Kinetics of humoral immunodeficiency with bispecific antibody therapy in multiple myeloma

Background: Bispecific antibodies (bsAb) are a promising class of therapeutics in RRMM. While hypogammaglobinemia (HGG) is anticipated due to plasma cell depletion, there is a lack of information about the degree of secondary immunodeficiency and resultant infectious complications. We investigated the kinetics of HGG in patients with RRMM on bsAb therapy. Methods: We identified and followed 42 patients treated on early clinical trials of bsAb at our institution between 2019 and 2021. Serial immunoglobulin levels and infections were obtained from the start of therapy until last follow up or 3 months after study exit. Results: 49 treatment courses were included from 42 individual patients. All patients were triple class exposed with a median of 5 prior lines of therapy. The median age was 67 (44-85) years, with 49% females. African Americans accounted for 18% of patients. 96% of patients had at least one prior ASCT. 90% of patients received bsAb targeting BCMA including 7 patients who received more than one line of BCMA targeting therapies. At a median follow up 9.5 (0.9-28.6) months, 40.8% of patients remained on bsAb therapy. At the start of therapy, the median IgG, IgA, and IgM levels were 560 (44-9436), 15 (5-3886) and 6 (5-64) mg/dL, respectively and 50% of patients had severe HGG (≤400mg/dl). Serum IgG levels reached a nadir at 3 months while, IgA and IgM at 1 month, from the start of therapy. The median nadir levels of IgG were 159 (40-2996) mg/dL, while it was < 5 mg/dL for both IgA and IgM. IgG levels were below the detectable range (< 40 mg/dl) in 28% of patients at some point during therapy. IgA and IgM were also below the detectable range (< 5 mg/dl) in 50% and 60% of patients, respectively. At last follow-up, the median IgG levels were 444 (40-1860) mg/dL and IgA 5 (5-254) mg/dL and IgM 5 (5-44) mg/dL. Additionally, 38% of patients remained severely hypogammaglobinemic. 57% (24/42) of patients received IVIG supplements in the current series. About 71% of patients had at least one infectious event and the cumulative incidence of infections progressively increased with increasing duration of therapy with risk at 3, 6, 9 12, 15 months being 41%, 57%, 64%, 67% and 70%, respectively. Among these, 54% of infection were bacterial. Viral infection accounted for 41% of infections. A third of patients had new infectious events during the first 90 days following stopping bsAb treatment. 57% (8/14) of patients did not mount a response to the primary COVID19 immunization series. Among the five patients with repeat antibody titers after the booster dose, 50% were still not able to mount an antibody response. Conclusions: bsAb therapy in RRMM can be associated with profound and prolonged HGG. The cumulative risk of infection correlated with the degree of HGG and progressively increases with treatment and persisted months after being off therapy. Additionally, an impaired antibody response to the COVID-19 immunization series was also noted.

A Bispecific Antibody Targeting RBD and S2 Potently Neutralizes SARS-CoV-2 Omicron and Other Variants of Concern.

Emerging severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) variants, especially the Omicron variant, have impaired the efficacy of existing vaccines and most therapeutic antibodies, highlighting the need for additional antibody-based tools that can efficiently neutralize emerging SARS-CoV-2 variants. The use of a "single" agent to simultaneously target multiple distinct epitopes on the spike is desirable in overcoming the neutralizing escape of SARS-CoV-2 variants. Herein, we generated a human-derived IgG-like bispecific antibody (bsAb), Bi-Nab35B5-47D10, which successfully retained parental specificity and simultaneously bound to the two distinct epitopes on receptor-binding domain (RBD) and S2. Bi-Nab35B5-47D10 showed improved spike binding breadth among wild-type (WT) SARS-CoV-2, variants of concern (VOCs), and variants being monitored (VBMs) compared with its parental monoclonal antibodies (MAbs). Furthermore, pseudotyped virus neutralization demonstrated that Bi-Nab35B5-47D10 can efficiently neutralize VBMs, including Alpha (B.1.1.7), Beta (B.1.351), and Kappa (B.1.617.1), as well as VOCs, including Delta (B.1.617.2), Omicron BA.1, and Omicron BA.2. Crucially, Bi-Nab35B5-47D10 substantially improved neutralizing activity against Omicron BA.1 (IC50 = 0.15 nM) and Omicron BA.2 (IC50 = 0.67 nM) compared with its parental MAbs. Therefore, Bi-Nab35B5-47D10 represents a potential effective countermeasure against SARS-CoV-2 Omicron and other variants of concern. IMPORTANCE The new, highly contagious SARS-CoV-2 Omicron variant caused substantial breakthrough infections and has become the dominant strain in countries across the world. Omicron variants usually bear high mutations in the spike protein and exhibit considerable escape of most potent neutralization monoclonal antibodies and reduced efficacy of current COVID-19 vaccines. The development of neutralizing antibodies with potent efficacy against the Omicron variant is still an urgent priority. Here, we generated a bsAb, Bi-Nab35B5-47D10, which simultaneously targets SARS-CoV-2 RBD and S2 and improves the neutralizing potency and breadth against SARS-CoV-2 WT and the tested variants compared with their parental antibodies. Notably, Bi-Nab35B5-47D10 has more potent neutralizing activity against the VOC Omicron pseudotyped virus. Therefore, Bi-Nab35B5-47D10 is a feasible and potentially effective strategy by which to treat and prevent COVID-19.

Superimmunity by pan-sarbecovirus nanobodies.

Vaccine boosters and infection can facilitate the development of SARS-CoV-2 antibodies with improved potency and breadth. Here, we observe superimmunity in a camelid extensively immunized with the SARS-CoV-2 receptor-binding domain (RBD). We rapidly isolate a large repertoire of specific ultra-high-affinity nanobodies that bind strongly to all known sarbecovirus clades using integrative proteomics. These pan-sarbecovirus nanobodies (psNbs) are highly effective against SARS-CoV and SARS-CoV-2 variants, including Omicron, with the best median neutralization potency at single-digit nanograms per milliliter. A highly potent, inhalable, and bispecific psNb (PiN-31) is also developed. Structural determinations of 13 psNbs with the SARS-CoV-2 spike or RBD reveal five epitope classes, providing insights into the mechanisms and evolution of their broad activities. The highly evolved psNbs target small, flat, and flexible epitopes that contain over 75% of conserved RBD surface residues. Their potencies are strongly and negatively correlated with the distance of the epitopes from the receptor binding sites.