The value of bispecific antibodies in relapsed and refractory DLBCL

Diffuse large B-cell lymphoma (DLBCL) may be cured with anti-CD20 based chemoimmunotherapy in the majority of cases, however, relapsed/refractory disease occurs in 30-40% patients, and despite significant recent therapeutic advances, continues to represent an unmet clinical need. Bispecific antibodies represent a novel class of therapy currently in development for relapsed/refractory B-cell lymphoma. This review discusses the background clinical need, mechanism of action, and clinical data including efficacy and toxicity for bispecific antibodies in DLBCL, focusing on the most advanced class in development; CD20 targeting T-cell engaging antibodies. Emerging possibilities for future use of bispecific antibodies is also discussed, including novel and cytotoxic combination regimens in relapsed and first-line settings.

Persistent SARS-CoV-2 infection in patients with B-cell deficiency: a case series of successful antiviral treatment of four patients

Persistent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in immunocompromised patients remains a major medical challenge. Diagnosing the syndrome is difficult as symptoms may mimic other diseases and treatment guidelines are lacking. We describe a case series of four patients with persistent SARS-CoV-2 infection that all had an underlying B-cell deficiency due to rituximab treatment (in one case in combination with epcoritamab). In all four patients, it was initially difficult to recognize the persistent disease, leading to a duration of illness between 45 and 242 days. Two patients were only positive for SARS-CoV-2 by polymerase chain reaction (PCR) in the nasopharynx at the beginning of the disease but were later repeatedly negative. However, when bronchoalveolar lavage was performed, a positive SARS-CoV-2 PCR was revealed from the lower airways in both patients. The difficulties establishing diagnosis contributed to these two patients' long disease course. The longest disease duration was in the patient treated with rituximab and epcoritamab, who also responded poorly to single standard antiviral treatment. This patient ultimately cleared the infection after administering a combination treatment with remdesivir and nirmatrelvir/ritonavir. After a confirmed diagnosis, the other three patients cleared the infection when they were finally treated with antivirals. Increasing clinicians' awareness of this condition is important as it might be treatable once diagnosed. Further studies are warranted to define the condition and treatment strategy with greater precision.

Promising Immunotherapeutic Modalities for B-Cell Lymphoproliferative Disorders

Over the last few years, treatment principles have been changed towards more targeted therapy for many B-cell lymphoma subtypes and in chronic lymphocytic leukemia (CLL). Immunotherapeutic modalities, namely monoclonal antibodies (mAbs), bispecific antibodies (bsAbs), antibody-drug conjugates (ADCs), and chimeric antigen receptor T (CAR-T) cell therapy, commonly use B-cell-associated antigens (CD19, CD20, CD22, and CD79b) as one of their targets. T-cell engagers (TCEs), a subclass of bsAbs, work on a similar mechanism as CAR-T cell therapy without the need of previous T-cell manipulation. Currently, several anti-CD20xCD3 TCEs have demonstrated promising efficacy across different lymphoma subtypes with slightly better outcomes in the indolent subset. Anti-CD19xCD3 TCEs are being developed as well but only blinatumomab has been evaluated in clinical trials yet. The results are not so impressive as those with anti-CD19 CAR-T cell therapy. Antibody-drug conjugates targeting different B-cell antigens (CD30, CD79b, CD19) seem to be effective in combination with mAbs, standard chemoimmunotherapy, or immune checkpoint inhibitors. Further investigation will show whether immunotherapy alone or in combinatory regimens has potential to replace chemotherapeutic agents from the first line treatment.