Checkpoint Inhibitors in Multiple Myeloma: Intriguing Potential and Unfulfilled Promises

Challenges and strategies associated with CAR-T cell therapy in blood malignancies

Cellular immunotherapy, particularly CAR-T cells, has shown potential in the improvement of outcomes in patients with refractory and recurrent malignancies of the blood. However, achieving sustainable long-term complete remission for blood cancer remains a challenge, with resistance and relapse being expected outcomes for many patients. Although many studies have attempted to clarify the mechanisms of CAR-T cell therapy failure, the mechanism remains unclear. In this article, we discuss and describe the current state of knowledge regarding these factors, which include elements that influence the CAR-T cell, cancer cells as a whole, and the microenvironment surrounding the tumor. In addition, we propose prospective approaches to overcome these obstacles in an effort to decrease recurrence rates and extend patient survival subsequent to CAR-T cell therapy.

Immune checkpoint expression patterns on T cell subsets in light-chain amyloidosis: VISTA, PD-1, and TIGIT as potential therapeutic targets

Amyloid light chain (AL) amyloidosis is a rare plasma cell dyscrasia with dismal prognosis. This study aims to investigate the T-cell immune checkpoint expression patterns in systemic AL amyloidosis and its relationship with clinicobiological traits. We examined the frequencies of V-domain immunoglobulin suppressor of T cell activation+ (VISTA+), programmed cell death 1+ (PD-1+), T cell immunoglobulin and mucin-domain-containing-3+ (Tim-3+), T cell immunoreceptor with Ig and ITIM domains+ (TIGIT+) T cells in peripheral blood (PB) and bone marrow (BM) from 19 patients with newly diagnosed AL amyloidosis. Patients with AL amyloidosis had significantly higher percentages of VISTA+ and PD-1+ T cells in PB than healthy individuals (HIs), with no statistical differences in BM. The percentages of some double-positive T cells in PB were also considerably higher in AL amyloidosis than those in HIs. Additionally, the patients with renal involvement had more PD-1+ and TIGIT+ T cells than the patients without, and PD-1+CD3+%, PD-1+CD4+%, PD-1+Treg% were positively correlated with 24-hour proteinuria levels. Furthermore, the AL amyloidosis patients had higher counts of PD-1+ Treg in PB than multiple myeloma (MM) patients, while the MM patients had higher counts of TIGIT+ T cells than AL amyloidosis patients. Collectively, this is the first report of elevated proportions of VISTA+ and PD-1+ T cells in PB of AL amyloidosis patients, indicating an immunosuppressive milieu, and the increased PD-1+ and TIGIT+ T cells were associated with renal damage. VISTA, PD-1, and TIGIT may be potential targets for reversing T-cell exhaustion in AL amyloidosis.

Immune checkpoint inhibitors for multiple myeloma immunotherapy

Multiple myeloma (MM) is related to immune disorders, recent studys have revealed that immunotherapy can greatly benefit MM patients. Immune checkpoints can negatively modulate the immune system and are closely associated with immune escape. Immune checkpoint-related therapy has attracted much attention and research in MM. However, the efficacy of those therapies need further improvements. There need more thoughts about the immune checkpoint to translate their use in clinical work. In our review, we aggregated the currently known immune checkpoints and their corresponding ligands, further more we propose various ways of potential translation applying treatment based on immune checkpoints for MM patients.

Current status of drug development for patients with multiple myeloma: a review of comparison in China and the rest of world

Multiple myeloma (MM) is a highly heterogeneous malignancy. The treatment of MM has been significantly advanced in recent years. B cell maturation antigen (BCMA)-targeted immunotherapy and chimeric antigen receptor T (CAR-T) cell therapy have been approved for the treatment of relapsed and refractory MM (RRMM), which will be launched in China shortly. The CD38 (cluster of differentiation 38) antibody, daratumumab, improves the clinical outcomes both RRMM and newly diagnosed MM patients. The combination of daratumumab, bortezomib and dexamethasone achieved favorable outcomes as the first-line therapy in China. However, high-risk patients have limited benefits from these advanced therapeutics, and usually relapse early, progressing into aggressive end-stage MM. Therefore, novel therapies are sought to improve the cancer prognosis in these patients. This review furnishes an overview of the recent clinical developments of these novel drugs and compares the drug candidates under development in China to the rest of the world.

Inappropriate Expression of PD-1 and CTLA-4 Checkpoints in Myeloma Patients Is More Pronounced at Diagnosis: Implications for Time to Progression and Response to Therapeutic Checkpoint Inhibitors

Multiple myeloma (MM) is a hematologic malignancy characterized by severely profound immune dysfunction. Therefore, the efficacy of drugs targeting the immune environments, such as immune checkpoint inhibitors (ICIs), is of high clinical importance. However, several clinical trials evaluating ICIs in MM in different therapeutic combinations revealed underwhelming results showing a lack of clinical efficacy and excessive side effects. The underlying mechanisms of resistance to ICIs observed in the majority of MM patients are still under investigation. Recently, we demonstrated that inappropriate expression of PD-1 and CTLA-4 on CD4 T cells in active MM is associated with adverse clinical outcomes and treatment status. The aim of the current study was to determine the usefulness of immune checkpoint expression assessment as a predictive biomarker of the response to therapeutic inhibitors. For this purpose, along with checkpoint expression estimated by flow cytometry, we evaluated the time to progression (TTP) of MM patients at different clinical stages (disease diagnosis and relapse) depending on the checkpoint expression level; the cut-off point (dividing patients into low and high expressors) was selected based on the median value. Herein, we confirmed the defective levels of regulatory PD-1, CTLA-4 receptors, and the CD69 marker activation in newly diagnosed (ND) patients, whereas relapsed/refractory patients (RR) exhibited their recovered values and reactivity. Additionally, substantially higher populations of senescent CD4+CD28− T cells were found in MM, primarily in NDMM subjects. These observations suggest the existence of two dysfunctional states in MM CD4 T cells with the predominance of immunosenescence at disease diagnosis and exhaustion at relapse, thus implying different responsiveness to the external receptor blockade depending on the disease stage. Furthermore, we found that lower CTLA-4 levels in NDMM patients or higher PD-1 expression in RRMM patients may predict early relapse. In conclusion, our study clearly showed that the checkpoint level in CD4 T cells may significantly affect the time to MM progression concerning the treatment status. Therefore, when considering novel therapies and potent combinations, it should be taken into account that blocking PD-1 rather than CTLA-4 might be a beneficial form of immunotherapy for only a proportion of RRMM patients.