New Biological Therapies for Multiple Myeloma.

Multiple myeloma is a cancer of bone marrow plasma cells that represents approximately 10% of hematologic malignancies. Though it is typically incurable, a remarkable suite of new therapies developed over the last 25 years has enabled durable disease control in most patients. This article briefly introduces the clinical features of multiple myeloma and aspects of multiple myeloma biology that modern therapies exploit. Key current and emerging treatment modalities are then reviewed, including cereblon-modulating agents, proteasome inhibitors, monoclonal antibodies, other molecularly targeted therapies (selinexor, venetoclax), chimeric antigen receptor T cells, T cell-engaging bispecific antibodies, and antibody-drug conjugates. For each modality, mechanism of action and clinical considerations are discussed. These therapies are combined and sequenced in modern treatment pathways, discussed at the conclusion of the article, which have led to substantial improvements in outcomes for multiple myeloma patients in recent years.

Exploiting the CD200-CD200R immune checkpoint axis in multiple myeloma to enhance CAR T-cell therapy.

ABSTRACT: Patients with multiple myeloma (MM) treated with B-cell maturation antigen (BCMA)-specific chimeric antigen receptor (CAR) T cells usually relapse with BCMA+ disease, indicative of CAR T-cell suppression. CD200 is an immune checkpoint that is overexpressed on aberrant plasma cells (aPCs) in MM and is an independent negative prognostic factor for survival. However, CD200 is not present on MM cell lines, a potential limitation of current preclinical models. We engineered MM cell lines to express CD200 at levels equivalent to those found on aPCs in MM and show that these are sufficient to suppress clinical-stage CAR T-cells targeting BCMA or the Tn glycoform of mucin 1 (TnMUC1), costimulated by 4-1BB and CD2, respectively. To prevent CD200-mediated suppression of CAR T cells, we compared CRISPR-Cas9-mediated knockout of the CD200 receptor (CD200RKO), to coexpression of versions of the CD200 receptor that were nonsignaling, that is, dominant negative (CD200RDN), or that leveraged the CD200 signal to provide CD28 costimulation (CD200R-CD28 switch). We found that the CD200R-CD28 switch potently enhanced the polyfunctionality of CAR T cells, and improved cytotoxicity, proliferative capacity, CAR T-cell metabolism, and performance in a chronic antigen exposure assay. CD200RDN provided modest benefits, but surprisingly, the CD200RKO was detrimental to CAR T-cell activity, adversely affecting CAR T-cell metabolism. These patterns held up in murine xenograft models of plasmacytoma, and disseminated bone marrow predominant disease. Our findings underscore the importance of CD200-mediated immune suppression in CAR T-cell therapy of MM, and highlight a promising approach to enhance such therapies by leveraging CD200 expression on aPCs to provide costimulation via a CD200R-CD28 switch.

Teclistamab in Relapsed or Refractory Multiple Myeloma.

BACKGROUND: Teclistamab is a T-cell-redirecting bispecific antibody that targets both CD3 expressed on the surface of T cells and B-cell maturation antigen expressed on the surface of myeloma cells. In the phase 1 dose-defining portion of the study, teclistamab showed promising efficacy in patients with relapsed or refractory multiple myeloma. METHODS: In this phase 1-2 study, we enrolled patients who had relapsed or refractory myeloma after at least three therapy lines, including triple-class exposure to an immunomodulatory drug, a proteasome inhibitor, and an anti-CD38 antibody. Patients received a weekly subcutaneous injection of teclistamab (at a dose of 1.5 mg per kilogram of body weight) after receiving step-up doses of 0.06 mg and 0.3 mg per kilogram. The primary end point was the overall response (partial response or better). RESULTS: Among 165 patients who received teclistamab, 77.6% had triple-class refractory disease (median, five previous therapy lines). With a median follow-up of 14.1 months, the overall response rate was 63.0%, with 65 patients (39.4%) having a complete response or better. A total of 44 patients (26.7%) were found to have no minimal residual disease (MRD); the MRD-negativity rate among the patients with a complete response or better was 46%. The median duration of response was 18.4 months (95% confidence interval [CI], 14.9 to not estimable). The median duration of progression-free survival was 11.3 months (95% CI, 8.8 to 17.1). Common adverse events included cytokine release syndrome (in 72.1% of the patients; grade 3, 0.6%; no grade 4), neutropenia (in 70.9%; grade 3 or 4, 64.2%), anemia (in 52.1%; grade 3 or 4, 37.0%), and thrombocytopenia (in 40.0%; grade 3 or 4, 21.2%). Infections were frequent (in 76.4%; grade 3 or 4, 44.8%). Neurotoxic events occurred in 24 patients (14.5%), including immune effector cell-associated neurotoxicity syndrome in 5 patients (3.0%; all grade 1 or 2). CONCLUSIONS: Teclistamab resulted in a high rate of deep and durable response in patients with triple-class-exposed relapsed or refractory multiple myeloma. Cytopenias and infections were common; toxic effects that were consistent with T-cell redirection were mostly grade 1 or 2. (Funded by Janssen Research and Development; MajesTEC-1 ClinicalTrials.gov numbers, NCT03145181 and NCT04557098.).

A randomized phase 2 trial of idiotype vaccination and adoptive autologous T-cell transfer in patients with multiple myeloma.

We hypothesized that combining adoptively transferred autologous T cells with a cancer vaccine strategy would enhance therapeutic efficacy by adding antimyeloma idiotype (Id)-keyhole limpet hemocyanin (KLH) vaccine to vaccine-specific costimulated T cells. In this randomized phase 2 trial, patients received either control (KLH only) or Id-KLH vaccine, autologous transplantation, vaccine-specific costimulated T cells expanded ex vivo, and 2 booster doses of assigned vaccine. In 36 patients (KLH, n = 20; Id-KLH, n = 16), no dose-limiting toxicity was seen. At last evaluation, 6 (30%) and 8 patients (50%) had achieved complete remission in KLH-only and Id-KLH arms, respectively (P = .22), and no difference in 3-year progression-free survival was observed (59% and 56%, respectively; P = .32). In a 594 Nanostring nCounter gene panel analyzed for immune reconstitution (IR), compared with patients receiving KLH only, there was a greater change in IR genes in T cells in those receiving Id-KLH relative to baseline. Specifically, upregulation of genes associated with activation, effector function induction, and memory CD8+ T-cell generation after Id-KLH but not after KLH control vaccination was observed. Similarly, in responding patients across both arms, upregulation of genes associated with T-cell activation was seen. At baseline, all patients had greater expression of CD8+ T-cell exhaustion markers. These changes were associated with functional Id-specific immune responses in a subset of patients receiving Id-KLH. In conclusion, in this combination immunotherapy approach, we observed significantly more robust IR in CD4+ and CD8+ T cells in the Id-KLH arm, supporting further investigation of vaccine and adoptive immunotherapy strategies. This trial was registered at www.clinicaltrials.gov as #NCT01426828.

Waldenström Macroglobulinemia/Lymphoplasmacytic Lymphoma, Version 2.2024, NCCN Clinical Practice Guidelines in Oncology.

The treatment of Waldenström macroglobulinemia/lymphoplasmacytic lymphoma (WM/LPL) has evolved to include several new options. The NCCN Guidelines for WM/LPL provide a framework on which to base decisions regarding diagnosis, treatment, assessment of response to treatment, and follow-up of both newly diagnosed and previously treated WM/LPL.

Combined deletion of cathepsin protease family members reveals compensatory mechanisms in cancer.

Proteases are important for regulating multiple tumorigenic processes, including angiogenesis, tumor growth, and invasion. Elevated protease expression is associated with poor patient prognosis across numerous tumor types. Several multigene protease families have been implicated in cancer, including cysteine cathepsins. However, whether individual family members have unique roles or are functionally redundant remains poorly understood. Here we demonstrate stage-dependent effects of simultaneously deleting cathepsin B (CtsB) and CtsS in a murine pancreatic neuroendocrine tumor model. Early in tumorigenesis, the double knockout results in an additive reduction in angiogenic switching, whereas at late stages, several tumorigenic phenotypes are unexpectedly restored to wild-type levels. We identified CtsZ, which is predominantly supplied by tumor-associated macrophages, as the compensatory protease that regulates the acquired tumor-promoting functions of lesions deficient in both CtsB and CtsS. Thus, deletion of multiple cathepsins can lead to stage-dependent, compensatory mechanisms in the tumor microenvironment, which has potential implications for the clinical consideration of selective versus pan-family cathepsin inhibitors in cancer.

Systemic Light Chain Amyloidosis, Version 2.2023, NCCN Clinical Practice Guidelines in Oncology.

Primary systemic light chain amyloidosis (SLCA) is characterized by production of light chains that get converted to amyloid fibrils with an affinity for visceral organs and causing organ dysfunction. The therapy for SLCA is directed to recovering the function of the affected organs by targeting the abnormal plasma cell clone and slowing deposition of amyloid fibrils. The NCCN Guidelines for SLCA provide recommendations for workup, diagnosis, and treatment of primary as well as previously treated SLCA.

Multiple Myeloma, Version 2.2024, NCCN Clinical Practice Guidelines in Oncology.

The treatment of relapsed/refractory multiple myeloma (MM) has evolved to include several new options. These include new combinations with second generation proteasome inhibitors (PI); second generation immunomodulators, monoclonal antibodies, CAR T cells, bispecific antibodies, selinexor, venetoclax, and many others. Most patients with MM undergo several cycles of remissions and relapse, and therefore need multiple lines of combination therapies. Selecting treatment options for relapsed/refractory MM requires consideration of resistance status to specific classes, and patient-specific factors such as age and other comorbidities should be considered. The NCCN Guidelines for MM provide a framework on which to base decisions regarding workup, treatment, and follow-up of newly diagnosed and previously treated MM. This manuscript outlines the recommendations from NCCN Guidelines for MM specific to relapsed/refractory disease.

Progressive multifocal leukoencephalopathy in multiple myeloma.

Progressive multifocal leukoencephalopathy (PML) is a rare and often fatal demyelinating disease of the central nervous system caused by reactivation of the JC virus in the context of immune suppression such as HIV, malignancy, and certain immunomodulatory medications. PML has been reported only rarely in multiple myeloma patients, and its presenting features and natural history in this population are not well known. We describe six cases of PML among multiple myeloma patients treated at our institution between 2013 and 2022, including two that developed on or shortly after treatment with recently developed BCMA-directed immunotherapies.

Teclistamab, a B-cell maturation antigen × CD3 bispecific antibody, in patients with relapsed or refractory multiple myeloma (MajesTEC-1): a multicentre, open-label, single-arm, phase 1 study.

BACKGROUND: There is a need for novel therapies for relapsed or refractory multiple myeloma, and B-cell maturation antigen (BCMA) is a validated target. Teclistamab is a bispecific antibody that binds BCMA and CD3 to redirect T cells to multiple myeloma cells. The aim of the MajesTEC-1 study was to evaluate the safety, tolerability, and preliminary efficacy of teclistamab in patients with relapsed or refractory multiple myeloma. METHODS: This open-label, single-arm, phase 1 study enrolled patients with multiple myeloma who were relapsed, refractory, or intolerant to established therapies. Teclistamab was administered intravenously (range 0·3-19·2 µg/kg [once every 2 weeks] or 19·2-720 µg/kg [once per week]) or subcutaneously (range 80-3000 µg/kg [once per week]) in different cohorts, with step-up dosing for 38·4 µg/kg or higher doses. The primary objectives were to identify the recommended phase 2 dose (part one) and characterise teclistamab safety and tolerability at the recommended phase 2 dose (part two). Safety was assessed in all patients treated with at least one dose of teclistamab. Efficacy was analysed in response-evaluable patients (ie, patients who received at least one dose of teclistamab and had at least one post-baseline response evaluation). This ongoing trial is registered with ClinicalTrials.gov, NCT03145181. FINDINGS: Between June 8, 2017, and March 29, 2021, 219 patients were screened for study inclusion, and 157 patients (median six previous therapy lines) were enrolled and received at least one dose of teclistamab (intravenous n=84; subcutaneous n=73). 40 patients were administered the recommended phase 2 dose, identified as once per week subcutaneous administration of teclistamab at 1500 µg/kg, after 60 µg/kg and 300 µg/kg step-up doses (median follow-up 6·1 months, IQR 3·6-8·2). There were no dose-limiting toxicities at the recommended phase 2 dose in part one. In the 40 patients treated at the recommended phase 2 dose, the most common treatment-emergent adverse events were cytokine release syndrome in 28 (70%; all grade 1 or 2 events) and neutropenia in 26 (65%) patients (grade 3 or 4 in 16 [40%]). The overall response rate in response-evaluable patients treated at the recommended phase 2 dose (n=40) was 65% (95% CI 48-79); 58% achieved a very good partial response or better. At the recommended phase 2 dose, the median duration of response was not reached. 22 (85%) of 26 responders were alive and continuing treatment after 7·1 months' median follow-up (IQR 5·1-9·1). At the recommended phase 2 dose, teclistamab exposure was maintained above target exposure levels, and consistent T-cell activation was reported. INTERPRETATION: Teclistamab is a novel treatment approach for relapsed or refractory multiple myeloma. At the recommended phase 2 dose, teclistamab showed promising efficacy, with durable responses that deepened over time, and was well tolerated, supporting further clinical development. FUNDING: Janssen Research & Development.

NCCN Guidelines® Insights: Multiple Myeloma, Version 3.2022.

The NCCN Guidelines for Multiple Myeloma provide recommendations for diagnosis, initial workup, treatment, follow-up, and supportive care for patients with various plasma cell neoplasms, including multiple myeloma. These NCCN Guidelines Insights highlight some of the important updates/changes specific to the treatment of patients with multiple myeloma in the 2022 version of the guidelines.

Femtomolar SARS-CoV-2 Antigen Detection Using the Microbubbling Digital Assay with Smartphone Readout Enables Antigen Burden Quantitation and Tracking.

BACKGROUND: High-sensitivity severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigen assays are desirable to mitigate false negative results. Limited data are available to quantify and track SARS-CoV-2 antigen burden in respiratory samples from different populations. METHODS: We developed the Microbubbling SARS-CoV-2 Antigen Assay (MSAA) with smartphone readout, with a limit of detection of 0.5 pg/mL (10.6 fmol/L) nucleocapsid antigen or 4000 copies/mL inactivated SARS-CoV-2 virus in nasopharyngeal (NP) swabs. We developed a computer vision and machine learning-based automatic microbubble image classifier to accurately identify positives and negatives and quantified and tracked antigen dynamics in intensive care unit coronavirus disease 2019 (COVID-19) inpatients and immunocompromised COVID-19 patients. RESULTS: Compared to qualitative reverse transcription-polymerase chain reaction methods, the MSAA demonstrated a positive percentage agreement of 97% (95% CI 92%-99%) and a negative percentage agreement of 97% (95% CI 94%-100%) in a clinical validation study with 372 residual clinical NP swabs. In immunocompetent individuals, the antigen positivity rate in swabs decreased as days-after-symptom-onset increased, despite persistent nucleic acid positivity. Antigen was detected for longer and variable periods of time in immunocompromised patients with hematologic malignancies. Total microbubble volume, a quantitative marker of antigen burden, correlated inversely with cycle threshold values and days-after-symptom-onset. Viral sequence variations were detected in patients with long duration of high antigen burden. CONCLUSIONS: The MSAA enables sensitive and specific detection of acute infections and quantification and tracking of antigen burden and may serve as a screening method in longitudinal studies to identify patients who are likely experiencing active rounds of ongoing replication and warrant close viral sequence monitoring.

Multiple Myeloma, Version 3.2021, NCCN Clinical Practice Guidelines in Oncology.

Multiple myeloma is a malignant neoplasm of plasma cells that accumulate in bone marrow, leading to bone destruction and marrow failure. This manuscript discusses the management of patients with solitary plasmacytoma, smoldering multiple myeloma, and newly diagnosed multiple myeloma.

NCCN Guidelines Insights: Multiple Myeloma, Version 1.2020.

The NCCN Guidelines for Multiple Myeloma provide recommendations for diagnosis, workup, treatment, follow-up, and supportive care for patients with monoclonal gammopathy of renal significance, solitary plasmacytoma, smoldering myeloma, and multiple myeloma. These NCCN Guidelines Insights highlight some of the important updates and changes in the 1.2020 version of the NCCN Guidelines for Multiple Myeloma.

Chimeric antigen receptor T cell immunotherapy for multiple myeloma: A review of current data and potential clinical applications.

Multiple myeloma (MM) is a malignant plasma cell disorder that remains incurable for most patients despite significant improvements achieved with modern therapy. Tumor evasion is a key process in the pathogenesis of MM and a compromised immune system is associated with more aggressive forms of the disease. In contrast, the emergence of myeloma-specific immune responses after both autologous and allogeneic stem cell transplantation is associated with better prognosis. Adoptive T cell therapies may improve specific anti-myeloma immunity resulting in long-lasting remissions. CAR T cell therapies for MM are at an early stage of clinical development. To date, anti-BCMA CAR T cells have shown the greatest results in early-phase clinical trials. Toxicities have included cytokine release syndrome (CRS) and neurotoxicity. Current areas of research in CAR T cell therapies include the use of gene-editing to enhance their effectiveness and safety, the integration of CAR T cells with other therapies (immunomodulatory drugs, checkpoint inhibitors) and CAR T cells to target multiple antigens.

Macrophages and cathepsin proteases blunt chemotherapeutic response in breast cancer.

The microenvironment is known to critically modulate tumor progression, yet its role in regulating treatment response is poorly understood. Here we found increased macrophage infiltration and cathepsin protease levels in mammary tumors following paclitaxel (Taxol) chemotherapy. Cathepsin-expressing macrophages protected against Taxol-induced tumor cell death in coculture, an effect fully reversed by cathepsin inhibition and mediated partially by cathepsins B and S. Macrophages were also found to protect against tumor cell death induced by additional chemotherapeutics, specifically etoposide and doxorubicin. Combining Taxol with cathepsin inhibition in vivo significantly enhanced efficacy against primary and metastatic tumors, supporting the therapeutic relevance of this effect. Additionally incorporating continuous low-dose cyclophosphamide dramatically impaired tumor growth and metastasis and improved survival. This study highlights the importance of integrated targeting of the tumor and its microenvironment and implicates macrophages and cathepsins in blunting chemotherapeutic response.

Chimeric Antigen Receptor T Cells against CD19 for Multiple Myeloma.

A patient with refractory multiple myeloma received an infusion of CTL019 cells, a cellular therapy consisting of autologous T cells transduced with an anti-CD19 chimeric antigen receptor, after myeloablative chemotherapy (melphalan, 140 mg per square meter of body-surface area) and autologous stem-cell transplantation. Four years earlier, autologous transplantation with a higher melphalan dose (200 mg per square meter) had induced only a partial, transient response. Autologous transplantation followed by treatment with CTL019 cells led to a complete response with no evidence of progression and no measurable serum or urine monoclonal protein at the most recent evaluation, 12 months after treatment. This response was achieved despite the absence of CD19 expression in 99.95% of the patient's neoplastic plasma cells. (Funded by Novartis and others; ClinicalTrials.gov number, NCT02135406.).

IL-4 induces cathepsin protease activity in tumor-associated macrophages to promote cancer growth and invasion.

Innate immune cells can constitute a substantial proportion of the cells within the tumor microenvironment and have been associated with tumor malignancy in patients and animal models of cancer; however, the mechanisms by which they modulate cancer progression are incompletely understood. Here, we show that high levels of cathepsin protease activity are induced in the majority of macrophages in the microenvironment of pancreatic islet cancers, mammary tumors, and lung metastases during malignant progression. We further show that tumor-associated macrophage (TAM)-supplied cathepsins B and S are critical for promoting pancreatic tumor growth, angiogenesis, and invasion in vivo, and markedly enhance the invasiveness of cancer cells in culture. Finally, we demonstrate that interleukin-4 (IL-4) is responsible for inducing cathepsin activity in macrophages in vitro and in vivo. Together, these data establish IL-4 as an important regulator, and cathepsin proteases as critical mediators, of the cancer-promoting functions of TAMs.

Matching at Human Leukocyte Antigen-C Improved the Outcomes after Double Umbilical Cord Blood Transplantation for Recipients of Two to Four of Six Human Leukocyte Antigen-Matched Grafts.

We studied the effect of HLA-C matching in 515 patients after double umbilical cord blood (UCB) transplantation. After HLA matching HLA-A, -B, and -DRB1 at the allele level, we scored patients according to number of donor-recipient HLA-C matches at 4 possible loci: 2 from each donor unit, at the allele level. Given a direct interaction between HLA-A, -B, and -DRB1 matching and HLA-C score, we analyzed HLA-C matching in those receiving at least 1 2/6 to 4/6 HLA-matched unit (n = 389) versus those receiving only 5/6 or 6/6-matched units (n = 126). In those with at least 1 2/6 to 4/6 HLA-matched unit, a better HLA-C matching score was associated with significantly lower risk of death of any cause and nonrelapse mortality and better disease-free survival. There was no association with the risk of relapse, acute and chronic graft-versus-host disease, and hematopoietic recovery. In contrast, among patients receiving only allele-level 5/6 or 6/6 HLA-matched UCB units, HLA-C match had no demonstrable effect on any outcome. For patients receiving at least 1 allele-level 2/6 to 4/6 HLA-matched UCB unit, matching at HLA-C reduces nonrelapse mortality and improves survival.