Overall survival of patients with triple-class refractory multiple myeloma treated with selinexor plus dexamethasone vs standard of care in MAMMOTH

Real-world outcome of patients with extensively pretreated multiple myeloma who were treated with selinexor and dexamethasone: a Korean multicenter retrospective analysis

The outcomes of patients with myeloma after exposed to penta-classes are extremely poor. Selinexor is the first approved exportin inhibitor for those patients, but intractable toxicities may limit its use. This retrospective study evaluated the real-world efficacy and safety of selinexor plus dexamethasone (XD) and involved 48 patients with multiple myeloma, who were treated from November 2020 to October 2022. Their median age was 64 years, and the median number of prior lines of therapy was 6. The overall response rate was 25%, and the median progression-free survival (PFS) was 2.1 months (95% confidence interval (CI), 1.7-2.5). Patients on a reduced initial dose, delayed treatment, and dose reduction had better PFS. After XD treatment failure, 17 patients received subsequent therapy and had a median PFS of 2.4 months. The median overall survival was 4.6 months (95% CI, 2.3-6.9). Among the patients, 12 (25%) and 17 (35%) experienced dose reduction and delayed treatment, respectively. Our data show that the real-world efficacy of XD treatment in heavily pretreated patients was modest and that improving treatment adherence through reducing initial doses or delaying treatments may improve patient outcomes.

Selinexor-Based Triplet Regimens in Patients With Multiple Myeloma Previously Treated With Anti-CD38 Monoclonal Antibodies

BACKGROUND

The increasing use of anti-CD38 monoclonal antibodies (αCD38 mAbs) for newly diagnosed or early relapsed multiple myeloma (MM), especially in non-transplant eligible patients, may lead to more patients developing αCD38 mAb-refractory disease earlier in the treatment course with fewer treatment options.

PATIENTS AND METHODS

We analyzed the efficacy and safety of selinexor-based triplets (selinexor+dexamethasone [Sd] plus pomalidomide [SPd, n = 23], bortezomib [SVd, n = 16] or carfilzomib (SKd, n = 23]) in a subset of STOMP (NCT02343042) and BOSTON (NCT03110562) study patients treated previously with αCD38 mAbs.

RESULTS

Sixty-two patients (median 4 prior therapies, range 1 to 11, 90.3% refractory to αCD38 mAb) were included. Overall response rates (ORR) in the SPd, SVd and SKd cohorts were 52.2%, 56.3%, and 65.2%, respectively. Overall response rate was 47.4% among patients who had MM refractory to the third drug reintroduced in the Sd-based triplet. Median progression-free survival in the SPd, SVd, and SKd cohorts was 8.7, 6.7, and 15.0 months, respectively, and median overall survival was 9.6, 16.9, and 33.0 months, respectively. Median time to discontinuation in the SPd, SVd, and SKd cohorts was 4.4, 5.9, and 10.6 months, respectively. The most common hematological adverse events were thrombocytopenia, anemia, and neutropenia. Nausea, fatigue, and diarrhea were primarily grade 1/2. Adverse events were generally manageable with standard supportive care and dose modifications.

CONCLUSION

Selinexor-based regimens may offer effective and well-tolerated therapy to patients with relapsed and/or refractory MM who had disease previously exposed or refractory to αCD38 mAb therapy and could help address the unmet clinical need in these high-risk patients.

Selinexor: Targeting a novel pathway in multiple myeloma

Selinexor is an orally bioavailable selective inhibitor of nuclear export compound that inhibits exportin-1 (XPO1), a novel therapeutic target that is overexpressed in multiple myeloma (MM) and is responsible for the transport of ∼220 nuclear proteins to the cytoplasm, including tumour suppressor proteins. Inhibition of this process has demonstrated substantial antimyeloma activity in preclinical studies, both alone and in combination with established MM therapeutics. Based on a clinical trial programme encompassing multiple combination regimens, selinexor-based therapy has been approved for the treatment of relapsed/refractory MM (RRMM), with selinexor-dexamethasone approved in the later-relapse setting for penta-refractory patients and selinexor-bortezomib-dexamethasone approved for patients who have received ≥1 prior therapy. Here, we provide a comprehensive review of the clinical data on selinexor-based regimens, including recent updates from the 2022 American Society of Hematology annual meeting, and summarise ongoing studies of this novel targeted agent in newly diagnosed MM and RRMM.

Real-world treatment patterns and outcomes of triple-class treated patients with multiple myeloma in the United States

OBJECTIVES

Although multiple myeloma (MM) survival has improved following the introduction of proteosome inhibitors, immunomodulatory drugs, and anti-CD38 therapies, patients become refractory to these agents. Real-world outcomes of triple-class exposed patients are limited and were investigated in this study.

METHODS

The Integra Connect Database was used to assess the treatment patterns of triple-class exposed patients with relapsed/refractory MM (RRMM) (January 2016-December 2019).

RESULTS

During this period, patients (N = 501) reached triple exposure in a median of three lines of therapy (LOTs) over 995 days. A new LOT was started in a median of 18 (1-691) days after triple exposure; 71% of the patients started a new LOT within 30 days. Throughout the follow-up period, 8% of the patients had a therapy gap greater than 90 days. Following triple exposure, 103/501 patients (21%) received only triple-class agents in subsequent LOTs, while 24 (4.8%) patients received only non-triple-class agents. The median apparent survival from initiation of first therapy after triple exposure was 308 days.

CONCLUSION

These results indicate that recycling of triple-class agents after previous exposure is widespread and prognosis in the RRMM population remains poor, highlighting the continuing unmet need for new agents with novel mechanisms to improve patient outcomes.

Bispecific Antibodies for the Treatment of Multiple Myeloma

PURPOSE OF REVIEW

Advances in multiple myeloma therapies have greatly improved outcomes for patients living with the disease, although to date there is yet to be a cure. Cellular and immunotherapies, approved or in development, offer the promise of significantly advancing toward that possibility. The aim of this review is to provide a synopsis and commentary on the current and future states of bispecific agents aimed at harnessing the antineoplastic potential of T-cells in treating and eradicating myeloma.

RECENT FINDINGS

Numerous bispecific agents are in clinical development with some on the precipice of regulatory approval. While BCMA remains the principal target, some agents are directed at novel targets such as GPRC5D and FcRH5. The constructs vary in design and pharmacokinetics which has dosing and administration implications. The toxicity profiles of these agents generally reflect that of other immune therapies, including cytokine release syndrome and rarely neurotoxicity, although immunosuppression has also led to elevated infection risks. However, the toxicities are generally manageable and offset by unprecedented efficacy seen in such heavily pretreated cohorts. Bispecific agents are poised to significantly alter the treatment paradigms for myeloma. They provide a convenient "off-the-shelf" platform with often deep and durable responses. Toxicities are often limited in duration and severity. In the early-phase trials, many patients have been able to remain on treatment for extended periods, even among those with high-risk features. Upcoming trials are likely to explore earlier implementation of these agents in order to offer this therapeutic opportunity to broader cohorts.

Ciltacabtagene autoleucel in patients with relapsed/refractory multiple myeloma: CARTITUDE-1 (phase 2) Japanese cohort

Chimeric antigen receptor (CAR) T cells targeting B-cell maturation antigen have shown positive responses in patients with multiple myeloma (MM). The phase 2 portion of the CARTITUDE-1 study of ciltacabtagene autoleucel (cilta-cel) included a cohort of Japanese patients with relapsed/refractory MM. Following a conditioning regimen of cyclophosphamide (300 mg/m² ) and fludarabine (30 mg/m² ), patients received a single cilta-cel infusion at a target dose of 0.75 × 10⁶ (range, 0.5-1.0 × 10⁶ CAR-positive viable T cells/kg). The primary endpoint was overall response rate (ORR; defined as partial response or better) by International Myeloma Working Group criteria. A key secondary endpoint was the rate of very good partial response (VGPR) or better (defined as VGPR, complete response, stringent complete response). This first analysis was performed at 6 months after the last patient received cilta-cel. Thirteen patients underwent apheresis, nine of whom received cilta-cel infusion. Eight patients who received cilta-cel at the target dose responded, yielding an ORR of 100%. Seven of eight (87.5%) patients achieved a VGPR or better. One additional patient who received a below-target dose of cilta-cel also achieved a best response of VGPR. MRD negativity (10^-5 threshold) was achieved in all six evaluable patients. Eight of nine (88.9%) patients who received cilta-cel infusion experienced a grade 3 or 4 adverse event, and eight (88.9%) patients experienced cytokine release syndrome (all grade 1 or 2). No CAR-T cell neurotoxicity was reported. A positive benefit/risk profile for cilta-cel was established for heavily pretreated Japanese patients with relapsed or refractory MM.

Selinexor therapy for multiple myeloma and non-Hodgkin lymphomas

PURPOSE OF REVIEW

In this review we highlight the most recent studies furthering the clinical development of selinexor, a novel exportin-1 inhibitor, for the treatment of multiple myeloma and non-Hodgkin lymphomas.

RECENT FINDINGS

Three pivotal trials, the SADAL trial for diffuse large B-cell lymphoma, and the BOSTON and selinexor treatment of refractory myeloma trials for multiple myeloma, have recently led to the regulatory approval of selinexor monotherapy or combination regimens. They are complemented by several earlier phase clinical trials with iterative combinations, adding selinexor to novel therapies and cytotoxic chemotherapy regimens at various stages in the disease courses. In some, selinexor appears synergistic, occasionally overcoming treatment refractoriness, whereas in other situations appears additive. Consistent issues with tolerability are seen across trials, although consensus guidelines on their preemption and management have recently been adopted which may improve treatment success. While comparative data are lacking, the efficacy of selinexor-based regimens does not approach that of contemporaneous cellular and immunotherapies.

SUMMARY

Selinexor is a novel and potentially synergistic therapy for lymphoid malignancies, although requires refined supportive measures and strategies to improve its efficacy. Likely, for continued success, it will need to identify niches that complement recent advances, such as bridging to cellular therapies or maintenance thereafter.

Evaluating the Therapeutic Potential of Idecabtagene Vicleucel in the Treatment of Multiple Myeloma: Evidence to Date

Over the past two decades, significant progress has been made in the diagnosis, risk assessment and treatment of patients with multiple myeloma, translating into remarkable improvements in survival outcomes. Yet, cure remains elusive, and almost all patients eventually experience relapse, particularly those with high-risk and refractory disease. Immune-based approaches have emerged as highly effective therapeutic options that have heralded a new era in the treatment of multiple myeloma. Idecabtagene vicleucel (ide-cel) is one such therapy that employs the use of genetically modified autologous T-cells to redirect immune activation in a tumor-directed fashion. It has yielded impressive responses even in patients with poor-risk disease and is the first chimeric antigen receptor (CAR) T-cell therapy to be approved for treatment in relapsed or refractory multiple myeloma. In this review, we examine the design and pharmacokinetics of ide-cel, audit evidence that led to its incorporation into the current treatment paradigm and provide insight into its clinical utilization with a focus on real-life intricacies.

The molecular mechanism and challenge of targeting XPO1 in treatment of relapsed and refractory myeloma

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Significant progress has been made on the treatment of MM during past two decades.

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Acquired drug-resistance continues to drive early relapse in primary refractory MM.

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XPO1 over-expression and cargo mislocalization are associated with drug-resistance.

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XPO1 inhibitor selinexor restores drug sensitivity to subsets of RR-MM cells.

Multiple myeloma (MM) treatment regimens have vastly improved since the introduction of immunomodulators, proteasome inhibitors, and anti-CD38 monoclonal antibodies; however, MM is considered an incurable disease due to inevitable relapse and acquired drug resistance. Understanding the molecular mechanism by which drug resistance is acquired will help create novel strategies to prevent relapse and help develop novel therapeutics to treat relapsed/refractory (RR)-MM patients. Currently, only homozygous deletion/mutation of TP53 gene due to “double-hits” on Chromosome 17p region is consistently associated with a poor prognosis. The exciting discovery of XPO1 overexpression and mislocalization of its cargos in the RR-MM cells has led to a novel treatment options. Clinical studies have demonstrated that the XPO1 inhibitor selinexor can restore sensitivity of RR-MM to PIs and dexamethasone. We will elaborate on the problems of MM treatment strategies and discuss the mechanism and challenges of using XPO1 inhibitors in RR-MM therapies while deliberating potential solutions.

Targeting XPO1-Dependent Nuclear Export in Cancer

Nucleocytoplasmic transport of macromolecules is tightly regulated in eukaryotic cells. XPO1 is a transport factor responsible for the nuclear export of several hundred protein and RNA substrates. Elevated levels of XPO1 and recurrent mutations have been reported in multiple cancers and linked to advanced disease stage and poor survival. In recent years, several novel small-molecule inhibitors of XPO1 were developed and extensively tested in preclinical cancer models and eventually in clinical trials. In this brief review, we summarize the functions of XPO1, its role in cancer, and the latest results of clinical trials of XPO1 inhibitors.

Idecabtagene vicleucel (ide-cel) CAR T-cell therapy for relapsed and refractory multiple myeloma

Idecabtagene vicleucel (ide-cel), a novel chimeric antigen receptor (CAR) T-cell therapy targeting B-cell maturation antigen (BCMA), has recently gained approval by the US FDA for relapsed and refractory multiple myeloma (RRMM) after multicenter trials have demonstrated unprecedented results in this difficult-to-treat subgroup of patients. As the first CAR T-cell product approved for myeloma, ide-cel is poised to become a practice-changing treatment option. This first-in-class therapeutic offers hope for more durable remissions, as well as better quality of life, following a single infusion in a group of patients that previously had little hope. This paper reviews the ide-cel product in terms of design, pharmacology, efficacy and toxicity as described in studies reported to date.

Novel Approaches Outside the Setting of Immunotherapy for the Treatment of Multiple Myeloma: The Case of Melflufen, Venetoclax, and Selinexor

Although the survival rate of patients with multiple myeloma has significantly improved in the last years thanks to the introduction of various classes of new drugs, such as proteasome inhibitors, immunomodulatory agents, and monoclonal antibodies, the vast majority of these subjects relapse with a more aggressive disease due to the acquisition of further genetic alterations that may cause resistance to current salvage therapies. The treatment of these often "triple" (or even more) refractory patients remains challenging, and alternative approaches are required to overcome the onset of that resistance. Immunotherapies with novel monoclonal, drug-conjugated, or bi-specific antibodies, as well as the use of chimeric antigen receptor T cells, have been recently developed and are currently investigated. However, other non-immunologic therapeutic regimens based on melfluflen, venetoclax, or selinexor, three molecules with new mechanisms of action, have also shown promising results in the setting of relapsed/refractory myeloma. Here we report the most recent literature data regarding these three drugs, focusing on their efficacy and safety in multiple myeloma.

KarMMa-RW: comparison of idecabtagene vicleucel with real-world outcomes in relapsed and refractory multiple myeloma

Patients with relapsed and refractory multiple myeloma (RRMM) who are triple-class exposed (to an immunomodulatory agent, proteasome inhibitor, and anti-CD38 antibody) have limited treatment options and there is no standard of care. Idecabtagene vicleucel (ide-cel, bb2121), a BCMA-directed CAR T-cell therapy, demonstrated efficacy in triple-class exposed RRMM patients in the KarMMa trial (NCT03361748). In this retrospective study (KarMMa-RW), patient-level data from triple-class exposed RRMM patients were merged into a single data model and compared with KarMMa using trimmed stabilized inverse probability of treatment weighting. Endpoints included overall response rate (ORR; primary), rate of very good partial response or better (≥VGPR), progression-free survival (PFS), and overall survival (OS). Of 1949 real-world triple-class exposed RRMM patients, 190 received subsequent (index) line of therapy and met KarMMa eligibility criteria (Eligible RRMM cohort). With a median follow-up of 13.3 months in KarMMa and 10.2 months in Eligible RRMM, ORR, and ≥VGPR were significantly improved in KarMMa versus Eligible RRMM (ORR, 76.4% vs 32.2%; ≥VGPR, 57.9% vs 13.7%; both P < 0.0001) as were PFS (11.6 vs 3.5 months; P = 0.0004) and OS (20.2 vs 14.7 months; P = 0.0006). This study demonstrated that ide-cel significantly improved responses and survival compared with currently available therapies in triple-class exposed RRMM.

How to Treat High-Risk Myeloma at Diagnosis and Relapse

Survival in multiple myeloma has improved greatly during the past 2 decades, but this change has primarily benefited patients who have standard-risk disease. Patients with high-risk disease remain a challenge to diagnose and treat. To improve their clinical outcomes, it is imperative to develop tools to readily identify them and to provide them with the most effective available treatments. The most widely used stratification system, the revised International Staging System, incorporates serum β-2 microglobulin, albumin, lactate dehydrogenase, and high-risk chromosomal abnormalities [del(17p), t(4;14), and t(14;16)]. Recent updates have included mutational status and chromosome 1q abnormalities. Plasma cell leukemia, extramedullary disease, circulating plasma cells, renal failure, and frailty are also associated with poor outcome. The treatment approach for a newly diagnosed patient with high-risk multiple myeloma should include induction therapy, autologous stem cell transplantation if appropriate, and maintenance therapy. Triplet therapy with a proteasome inhibitor, immunomodulatory drug, and steroid, with or without an anti-CD38 antibody, should be considered for induction, along with a proteasome inhibitor and/or immunomodulatory drug for maintenance. Aiming for a deep and sustained response is important. Similar principles apply at relapse, with close monitoring of response, especially extramedullary disease and active management of side effects, so that patients can continue therapy and benefit from treatment. Immune-based therapies, including autologous CAR T-cell-based therapies and bispecific antibodies, show promising activity in relapsed disease and are being actively explored in earlier disease settings. As the prognosis for high-risk disease remains poor, the future goal for this patient group is to develop specific clinical trials to explore novel approaches and therapies efficiently.