Promising Immunotherapeutic Modalities for B-Cell Lymphoproliferative Disorders

Innovative Combinations, Cellular Therapies and Bispecific Antibodies for Chronic Lymphocytic Leukemia: A Narrative Review

In the last few years, several agents targeting molecules that sustain the survival and the proliferation of chronic lymphocytic leukemia (CLL) cells have become clinically available. Most of these drugs target surface proteins, such as CD19 or CD20, via monoclonal or bispecific monoclonal antibodies (BsAbs), CAR T cells, intracellular proteins like BTK by using covalent or non-covalent inhibitors or BCL2 with first or second generation BH3-mimetics. Since the management of CLL is evolving quickly, in this review we highlighted the most important innovative treatments including novel double and triple combination therapies, CAR T cells and BsAbs for CLL. Recently, a large number of studies on novel combinations and newer strategic options for CLL therapy have been published or presented at international conferences, which were summarized and linked together. Although the management of treatment with a single continuous agent is easier, the emergence of protein mutations, long-term toxicities and costs are important concerns that favor the use of a fixed duration therapy. In the future, a measurable residual disease (MRD)-guided treatment cessation and MRD-based re-initiation of targeted therapy seems to be a more feasible approach, allowing identification of the patients who might benefit from continuous therapy or who might need a consolidation with BsAbs or CAR T cells to clear the neoplastic clone.

Overview of tumor immunotherapy based on approved drugs

Tumor immunotherapy has become a new hotspot for cancer treatment. Various immunotherapies, such as immune checkpoint inhibitors, oncolytic viruses (OVs), cytokines, and cancer vaccines, have been used to treat tumors. They operate through different mechanisms, along with certain toxicities and side effects. Understanding the mechanisms by which immunotherapy modulates the immune system is essential for improving the efficacy and managing these adverse effects. This article discusses various currently approved cancer immunotherapy mechanisms and related agents approved by the Food and Drug Administration, the European Medicines Agency, and the Medicines and Medical Devices Agency. We also review the latest progress in immune drugs approved by the National Medical Products Administration, including monoclonal antibodies, cytokines, OVs, and chimeric antigen receptor-T cell therapy, to help understand the clinical application of tumor immunotherapy.

Treatment of Double-Refractory Chronic Lymphocytic Leukemia-An Unmet Clinical Need

Recent years have seen significant improvement in chronic lymphocytic leukemia (CLL) management. Targeting B-cell lymphoma (BCL-2) and Bruton's kinase (BTK) have become the main strategies to restrain CLL activity. These agents are generally well tolerated, but the discontinuation of these therapies happens due to resistance, adverse effects, and Richter's transformation. A growing population of patients who have previously used both BTK inhibitors and BCL2 suffer from the constriction of the following regimens. This review explores the resistance mechanisms for both ibrutinib and venetoclax. Moreover, we present innovative approaches evaluated for treating double-refractory CLL.

Antibody-drug conjugates come of age in oncology

Antibody-drug conjugates (ADCs) combine the specificity of monoclonal antibodies with the potency of highly cytotoxic agents, potentially reducing the severity of side effects by preferentially targeting their payload to the tumour site. ADCs are being increasingly used in combination with other agents, including as first-line cancer therapies. As the technology to produce these complex therapeutics has matured, many more ADCs have been approved or are in late-phase clinical trials. The diversification of antigenic targets as well as bioactive payloads is rapidly broadening the scope of tumour indications for ADCs. Moreover, novel vector protein formats as well as warheads targeting the tumour microenvironment are expected to improve the intratumour distribution or activation of ADCs, and consequently their anticancer activity for difficult-to-treat tumour types. However, toxicity remains a key issue in the development of these agents, and better understanding and management of ADC-related toxicities will be essential for further optimization. This Review provides a broad overview of the recent advances and challenges in ADC development for cancer treatment.

Feasibility of in vivo CAR T cells tracking using streptavidin-biotin-paired positron emission tomography

BACKGROUND

A novel reporter system, streptavidin (SA)- [⁶⁸ Ga]Ga-labeled biotin ([⁶⁸ Ga]Ga-DOTA-biotin), was constructed and its ability for PET imaging the behaviors of CAR T cells were also evaluated in this study.

METHODS

In vitro activity and cytotoxicity of the SA transduced anti-CD19-CAR T (denoted as SA-CD19-CAR T) cells were determined. The feasibility of monitoring proliferation profiles of SA-CD19-CAR T cells using [⁶⁸ Ga]Ga-DOTA-biotin was firstly investigated in a solid tumor model. Also, the pharmacodynamics and pharmacokinetics of the CAR T cells in whole-body hematologic neoplasms were evaluated by bioluminescence imaging and [⁶⁸ Ga]Ga-DOTA-biotin PET imaging simultaneously.

RESULTS

After transduction with SA, the activity and cytotoxicity of the modified CAR T cells were not affected. PET images revealed that the uptakes of [⁶⁸ Ga]Ga-DOTA-biotin in CD19⁺ K562 solid tumors were 0.67 ± 0.32 ID%/g and 1.26 ± 0.13 ID%/g at 30 min and 96 h p.i. after administration of SA-CD19-CAR T cells respectively. It confirmed that the SA-CD19-CAR T cells could effectively inhibit the growth of Raji hematologic tumors. However, low radioactivity related to the proliferation of CD19-CAR T cells was detected in the Raji model.

CONCLUSION

SA-CD19-CAR T cells were constructed successfully without disturbing the antitumor functions of the cells. The proliferation of the CAR T cells in solid tumors could be early detected by [⁶⁸ Ga]Ga-DOTA-biotin PET imaging.

CD19 CAR-T Cell Therapy Induced Immunotherapy Associated Interstitial Pneumonitis: A Case Report

Background

Chimeric antigen receptor-modified T cells (CAR-T) targeting CD19 has produced a high durable response in refractory or relapsed diffuse large B-cell lymphoma. Besides well-known cytokine release syndrome (CRS) or immune effector cell–associated neurotoxicity syndrome during CAR-T cell therapy, there were several rarely encountered fatal complications.

Case Report

A 63-year-old male patient with refractory EBV-positive diffuse large B-cell lymphoma, developed interstitial pneumonitis with prolonged hypoxemia at 16 weeks after CD19 CAR-T cell therapy. There was no evidence of CRS and any infections. The patient recovered after intravenous immunoglobulin without tocilizumab or glucocorticoid administration. Now he is still in remission without interstitial pneumonitis 3 years after CAR-T cell therapy.

Conclusion

This is the first report of immunotherapy-associated interstitial pneumonitis after CAR-T cell therapy. Our finding suggested the importance of careful follow-up and proper treatments for immunotherapy-associated pneumonitis in the CAR-T cell therapy schedule.