Guidance for Use and dosing of Selinexor in Multiple Myeloma in 2021: Consensus From International Myeloma Foundation Expert Roundtable

Selinexor is a first in class selective inhibitor of nuclear export (SINE), blocks exportin 1 (XPO1), a protein transporter, that among other actions, shuttles cargo proteins such as tumor suppressor proteins (TSPs), the glucocorticoid receptor (GR), and oncoprotein messenger RNAs (mRNAs) across the nuclear membrane to cytoplasm. By blocking XPO1, selinexor facilitates nuclear preservation and activation of TSPs, and prevents mRNA translation of the oncoproteins leading to induction of apoptosis. The therapeutic value of selinexor in combination with dexamethasone has been successfully demonstrated in treating relapsed and/or refractory myeloma (RRMM), leading to the Food and Drug Administration (FDA) approval of selinexor in combination with dexamethasone in 2019 for the treatment of adult patients with RRMM who received at least 4 prior therapies and whose disease is refractory to at least 2 proteasome inhibitors, at least 2 immunomodulatory agents, and an anti-CD38 monoclonal antibody (mAb) - a pentarefractory myeloma. More recently, selinexor in combination with bortezomib and dexamethasone was approved by the FDA in December 2020, based on the BOSTON study among RRMM patients who had received at least one prior line of therapy. With more available safety and efficacy data supporting the increased interval between dosing of selinexor (and lesser cumulative weekly dosing) and schedule, contrary to the originally approved dose of 160 mg per week, the supportive care guidelines needed to be revisited. The current manuscript summarizes the supportive care solutions with weekly dosing of selinexor and identifies the ideal potential patient for selinexor treatment.

Disrupted radial and tibial microarchitecture in patients with monoclonal gammopathy of undetermined significance

Patients with monoclonal gammopathy of undetermined significance (MGUS) had abnormalities in volumetric BMD (vBMD), microarchitecture, and stiffness at both the radius and tibia by high-resolution peripheral quantitative CT compared to matched controls. This is the first report demonstrating that patients with MGUS have microarchitectural deficits at multiple skeletal sites.

INTRODUCTION

Fracture risk is elevated in patients with monoclonal gammopathy of undetermined significance (MGUS). However, the pathogenesis of bone disease in these patients is poorly understood. Prior work using high-resolution peripheral CT (HRpQCT) demonstrated abnormal microarchitecture at the radius, with predominantly cortical abnormalities. We hypothesized that patients with MGUS have abnormal microarchitecture at both radius and tibia compared to controls, reflecting global skeletal effects of the disease.

METHODS

This case-control study enrolled 36 subjects; patients with MGUS (n = 12) were matched 1:2 by age, sex, and race to controls (n = 24). Areal BMD (aBMD) was measured by DXA, vBMD, and microarchitecture by HRpQCT, and whole bone stiffness by finite element analysis. Serum was drawn for markers of bone metabolism and inflammation.

RESULTS

By DXA, MGUS patients had lower aBMD at the lumbar spine, femoral neck, and 1/3 radius. Markers of bone metabolism and inflammation did not differ. By HRpQCT at the radius, MGUS patients had lower total, trabecular and cortical density, lower trabecular number, and greater trabecular separation and heterogeneity. At the tibia, MGUS patients had lower total and trabecular density, lower trabecular number, greater separation and heterogeneity, and lower whole bone stiffness.

CONCLUSIONS

Patients with MGUS had lower vBMD, cortical, and trabecular abnormalities at the radius compared to matched controls. At the tibia, trabecular abnormalities predominated. These results suggest that in addition to previously described cortical deficits, deterioration of trabecular bone may contribute to a generalized skeletal fragility in patients with MGUS.

Bisphosphonates as antimyeloma drugs

In patients with symptomatic multiple myeloma (MM), bisphosphonate (BP) treatment has been widely used to prevent bone loss and preserve skeletal health because of its proven effects on inhibiting osteoclast-mediated bone resorption. In addition to their effects on osteoclasts, it is becoming increasingly evident that BPs may have additional effects on the bone microenvironment and cells other than osteoclasts that may potentially inhibit the development and progression of MM. This review focuses on the pathophysiology of MM with an emphasis on the events that drive MM progression within the bone and the mechanisms by which BPs may inhibit specific processes. The underlying molecular mechanisms that drive the modulation of cellular fate and function and consequent physiological outcomes are described. Direct effects on myeloma cell growth and survival and the interactions between myeloma cells and the bone microenvironment are discussed. Clinical evidence of the antimyeloma effects of BPs is emerging and is also reviewed.

A phase II multicenter study of CNTO 328, an anti-IL-6 monoclonal antibody, in patients (pts) with relapsed or refractory multiple myeloma (MM)

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Background: Relapsed/refractory MM constitutes a specific and unmet medical need with poor overall response and survival. Interleukin-6 (IL-6) plays an important role in MM cell proliferation, survival, and corticosteroid resistance and previous studies have shown clinical benefit from anti-IL-6 therapy. We therefore evaluated the combination of CNTO328, a chimeric monoclonal antibody with high affinity for human IL-6, and dexamethasone (dex) in pts with relapsed/refractory MM. Methods: Pts were treated with 6 mg/kg CNTO328 IV Q2 weeks. Oral dex (40mg) was given once daily, days 1–4, 9–12, and 17–20 for a max of 4 cycles; and on days 1–4 for subsequent cycles. Inclusion criteria were > 2 prior lines of systemic therapy, creatinine clearance >20 ml/min, platelets >50,000/mm3, and neutrophils >1000/mm3. Primary endpoint was overall response with secondary endpoints of time to progression, incidence of AEs and SAEs. Results: Thirty-nine pts received at least 1 infusion of CNTO328 in combination with dex - median age 66 yrs (range 43–89), median disease duration 4.2 yrs (1–13), median lines of prior therapy 5 (2–9) including bortezomib (100%), IMIDs (87%), and ASCT (59%). The median duration of therapy was 3.3 months (0.5–21+). Of the 36 pts who were evaluable, the overall response rate (CR+PR+MR) using EBMT criteria was 31% (7PR, 4MR). An additional 4 uMR and 4 SD lasting ≥3 months have been reported. PRs were durable; 6 out of 7 pts had responses ranging from 3 months to up to more than 1 year (with 1 still ongoing for more than 1 year). Duration of MRs ranged from 2–5 months. Responses were seen in pts relapsing after and refractory to at least one other prior treatment including bortezomib, IMIDs, or steroids. Median time to disease progression (PD) was 3.7 months (0.3–18+). Main reasons for treatment discontinuation were PD (24) and AEs (6). Hematologic toxicities Grade ≥ 3 were common though not dose-limiting. Three pts had Grade ≥ 3 infections considered reasonably related to CNTO328. Conclusions: CNTO 328 in combination with dex shows promising preliminary activity in this heavily pretreated patient population with an acceptable safety profile. Further investigation is ongoing.

No significant financial relationships to disclose.

PI3-K/AKT/FKHR and MAPK signaling cascades are redundantly stimulated by a variety of cytokines and contribute independently to proliferation and survival of multiple myeloma cells

IL-6 has been reported to play a central role in growth and survival of multiple myeloma (MM) cells. However, recently we have demonstrated that in the presence of bone marrow stromal cells, survival of MM cells becomes independent of the IL-6/gp130/STAT3 pathway questioning the singular role of IL-6 in MM. Therefore, it was the aim of this study to identify additional factors and signaling pathways that might contribute to the growth and survival of MM cells. We found that in addition to IL-6 a number of bone marrow derived cytokines such as LIF, VEGF, bFGF, MIP-1alpha, SDF-1alpha, IL-1beta, SCF and IL-3 activate the MAPK pathway and induce proliferation of MM.1S and RPMI-8226 MM cells. In addition, these cytokines independently phosphorylate the forkhead family member FKHR via PI3-K/AKT and support survival of primary human MM cells. Inhibition of these pathways induces apoptosis in MM cell lines and primary MM cells. Thus, we provide evidence that in addition to IL-6 a number of different factors trigger important growth-promoting pathways to support the proliferation and survival of MM cells. Therefore, blocking such pathways, rather than blocking a single factor, might be a promising approach for the development of novel treatment strategies in MM.

Immunomodulatory analogs of thalidomide inhibit growth of Hs Sultan cells and angiogenesis in vivo

We have previously shown that thalidomide and its potent immunomodulatory derivatives (IMiDs) inhibit the in vitro growth of multiple myeloma (MM) cell lines and patient MM cells that are resistant to conventional therapy. In this study, we further characterize the effect of these drugs on growth of B cell malignancies and angiogenesis. We established a beige-nude-xid (BNX) mouse model to allow for simultaneous in vivo measurement of both anti-tumor and anti-angiogenic effects of thalidomide and its analogs. Daily treatment (50 mg/kg/d) with thalidomide or IMiDs was nontoxic. The IMiDs were significantly more potent than thalidomide in vivo in suppressing tumor growth, evidenced by decreased tumor volume and prolonged survival, as well as mediating anti-angiogenic effects, as determined by decreased microvessel density. Our results therefore show that the IMiDs have more potent direct anti-tumor and anti-angiogenic effects than thalidomide in vivo, providing the framework for clinical protocols evaluating these agents in MM and other B cell neoplasms.

Adherence of multiple myeloma cells to bone marrow stromal cells upregulates vascular endothelial growth factor secretion: therapeutic applications

Increased angiogenesis has recently been recognized in active multiple myeloma (MM). Since vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) are two key mediators of angiogenesis, we characterized the production of VEGF, b-FGF and interleukin-6 (IL-6) (a MM growth and survival factor) in MM cell lines and Epstein-Barr virus (EBV) transformed B cell lines from MM patients, patient MM cells, as well as bone marrow stromal cells (BMSCs) from normal healthy donors and MM patients. We detected secretion of VEGF, but no bFGF and IL-6, in MM cell lines (MM.1S, RPMI 8226 and U266); EBV transformed B cell lines from MM patients (IM-9, HS-Sultan and ARH77); MM cell lines resistant to doxorubicin (RPMI-DOX40), mitoxantrone (RPMI-MR20), melphalan (RPMI-LR5) and dexamethasone (MM.1R); and patient MM cells (MM1 and MM2). BMSCs from MM patients and normal donors secreted VEGF, b-FGF and IL-6. Importantly, when MM cells were adhered to BMSCs, there was a significant increase in VEGF (1.5- to 3.1-fold) and IL-6 (1.9- to 56-fold) secretion. In contrast, the bFGF decreased in co-cultures of BMSCs and MM cells. Paraformaldehyde fixation of BMSCs or MM cells prior to adhesion revealed that VEGF was produced both from BMSCs and MM cells, though it may come primarily from BMSCs in some cultures. IL-6 was produced exclusively in BMSCs, rather than MM cells. Moreover, when MM cells were placed in Transwell insert chambers to allow their juxtaposition to BMSCs without cell to cell contact, induction of VEGF and IL-6 secretion persisted, suggesting the importance of humoral factors. Addition of exogenous IL-6 (10 ng/ml) increased VEGF secretion by BMSCs. Conversely, VEGF (100 ng/ml) significantly increased IL-6 secretion by BMSCs. Moreover, anti-human VEGF (1 microg/ml) and anti-human IL-6 (10 microg/ml) neutralizing antibodies reduced IL-6 and VEGF secretion, respectively, in cultures of BMSCs alone and co-cultures of BMSCs and MM cells. Finally, thalidomide (100 microM) and its immunomodulatory analog IMiD1-CC4047 (1 microM) decreased the upregulation of IL-6 and VEGF secretion in cultures of BMSCs, MM cells and co-cultures of BMSCs with MM cells. These data demonstrate the importance of stromal-MM cell interactions in regulating VEGF and IL-6 secretion, and suggest additional mechanisms whereby thalidomide and IMiD1-CC4047 act against MM cells in the BM millieu.

Mechanism of action of thalidomide and 3-aminothalidomide in multiple myeloma

We have explored the mechanism of the antiangiogenic effects of thalidomide by structure-activity studies. These investigations revealed that angiogenesis inhibition correlates with teratogenicity but not with tumor necrosis factor-alpha (TFA-alpha) inhibition. Additionally, one analog of thalidomide, 3-aminothalidomide, exhibited an unusual capacity to directly inhibit myeloma cell proliferation. This activity did not correlate with TNF-alpha inhibition. Thus 3-aminothalidomide was found to inhibit multiple myeloma through effects on both the tumor and vascular compartment. The effects of an inhibitor of both the tumor and vascular compartments of a tumor on tumor growth may be synergistic.

Vascular endothelial growth factor triggers signaling cascades mediating multiple myeloma cell growth and migration

Multiple myeloma (MM) remains incurable, with a median survival of 3 to 4 years. This study shows direct effects of vascular endothelial growth factor (VEGF) upon MM and plasma cell leukemia (PCL) cells. The results indicate that VEGF triggers tumor cell proliferation via a protein kinase C (PKC)-independent Raf-1-MEK-extracellular signal-regulated protein kinase pathway, and migration via a PKC-dependent pathway. These observations provide the framework for novel therapeutic strategies targeting VEGF signaling cascades in MM.

Thalidomide and immunomodulatory derivatives augment natural killer cell cytotoxicity in multiple myeloma

The antiangiogenic activity of thalidomide (Thal), coupled with an increase in bone marrow angiogenesis in multiple myeloma (MM), provided the rationale for the use of Thal in MM. Previously, the direct anti-MM activity of Thal and its analogues (immunomodulatory drugs, IMiDs) on MM cells was demonstrated, suggesting multiple mechanisms of action. In this study, the potential immunomodulatory effects of Thal/IMiDs in MM were examined. It was demonstrated that Thal/IMiDs do not induce T-cell proliferation alone but act as costimulators to trigger proliferation of anti-CD3-stimulated T cells from patients with MM, accompanied by an increase in interferon-gamma and IL-2 secretion. However, an increase in autologous T-cell killing of patient MM cells could not be demonstrated. A role for natural killer (NK)- and LAK-cell-mediated killing is suggested because IL-2-primed peripheral blood mononuclear cells (PBMCs) treated with Thal/IMiDs demonstrated significantly increased lysis of MM cell lines. Cold target inhibition assays suggested NK- rather than LAK-cell-mediated killing. Furthermore, this killing was not major histocompatibility complex-class restricted, and the depletion of CD56(+) cells blocked the drug-induced MM cell lysis. It was significant that increased killing of patient MM cells by autologous PBMCs treated with Thal/IMiDs was also observed. Although the in vivo relevance of NK-cell-mediated MM cell killing is unknown, phenotypic analysis performed in MM patients receiving Thal therapy demonstrated an increase in CD3(-)CD56(+) cells in patients responding to therapy. Thus in vitro and in vivo data support the hypothesis that Thal may mediate its anti-MM effect, at least in part, by modulating NK cell number and function.

Subclinical cardiotoxic effects of anthracyclines as assessed by magnetic resonance imaging-a pilot study

BACKGROUND

Anthracyclines are potent chemotherapeutics burdened by their cardiotoxicity. So far no marker to detect early cardiac damage exists. We tested the ability of magnetic resonance imaging (MRI) to show early changes in myocardial signal and cardiac function after anthracycline therapy.

METHODS

Twenty-two patients with normal cardiac function were investigated by MRI before and 3 and 28 days after anthracycline chemotherapy. Contrast enhanced fast spin echo images were obtained to characterize myocardial enhancement. Left ventricular ejection fraction was measured by MRI in contiguous short-axis planes.

RESULTS

All patients remained clinically stable. Ejection fraction decreased from 67.8% +/- 1.4% to 58.9% +/- 1.9% after 28 days (P < .05). The relative myocardial contrast enhancement increased from 3.8 +/- 0.4 to 6.9 +/- 1.1 (P < .01). An increase of the enhancement of >5 on day 3 compared with baseline predicted a significant loss of ejection fraction at 28 days (67.5% +/- 2.8% to 51.4% +/- 5.6%, mean difference 16.1% +/- 6.6%; P < .05), whereas an increase of +5 was not associated with a significant loss of ejection fraction (67.6% +/- 1.7% to 62.5% +/- 1.4%, mean difference 4.1% +/- 2.6%; P not significant).

CONCLUSIONS

MRI detects early changes in myocardial contrast and slightly deteriorating cardiac function in patients receiving anthracyclines. Larger patient cohorts and longer follow-up are needed to evaluate MRI as a predictor for anthracycline cardiotoxicity.

Brain metastases in breast cancer: prognostic factors and management

In this retrospective study, 162 breast cancer patients were analysed in whom brain metastases had been diagnosed clinically between 1969 and 1995 at a single institution. 145 patients were treated with megavoltage irradiation (60 cobalt or 6MV) of the whole brain using opposed fields. The most common applied schedule consisted of 30 Gy in 15 daily fractions over 3 weeks. 10 patients underwent surgery and 17 patients received symptomatic treatment only. The median age was 50 years (range 30-78 years). 81 of 162 patients (50%) were premenopausal. Women younger than 40 years of age had a shorter survival (median 12 weeks) than those of all other groups (median 29 weeks). Median survival was 82 weeks for the 10 surgical patients, 26 weeks for the 145 patients treated with radiotherapy and 5 weeks for the patients who received symptomatic (corticosteroid) therapy only. Patients with solitary metastases treated with radiation alone (45 patients) had a survival of 44 weeks versus 23 weeks in patients with multiple brain metastases. Multivariate stepwise regression analyses revealed Karnofsky Index, dose of radiation (P < 0.001), solitary metastases (P < 0.04) and primary tumour size (P < 0.04) as significant prognostic factors for survival.

Combined positive/negative purging and transplantation of peripheral blood progenitor cell autografts in breast cancer patients: a pilot study

This trial studied the feasibility and efficiency of a novel procedure of double purging to eliminate tumor cells from leukapheresis products of stage IV breast cancer patients. After induction and mobilization therapy, 35 leukapheresis products from 16 breast cancer patients were subjected to CD34+ enrichment (i.e., positive selection) with the Isolex 300 device and subsequent immunomagnetic depletion of tumor cells (i.e., negative selection) using a cocktail of three monoclonal antibodies directed against epithelial antigens. Patients with clinical response to induction chemotherapy proceeded to tandem high-dose chemotherapy, which consisted of melphalan (140 mg/m2) followed by retransfusion of the purged graft. After hematologic recovery, patients received ifosfamide 14 g/m2, carboplatin 1.5 g/m2, and etoposide 1.5g/m2 (ICE), again followed by autografting. After positive selection, a median purity of 96.6% CD34+ cells (range 48.4-99.2%) and a recovery of 56.8% (range 25.8-92.6%) were achieved. Subsequent negative purging resulted in a median CD34+ purity of 97.2%. Overall CD34+ recovery after both purging procedures was 51.1% (range 18.5-82.4%). Tumor cells were detectable in 8 of 16 (50%) starting fractions before purging. After both purging cycles, only 1 of 16 autografts remained positive for tumor cells compared to 3 of 16 after CD34+ selection. A calculated purging efficiency of 2 to >4 log was achieved. Engraftment was rapid, reaching > or =500/microL neutrophils on day +10 after melphalan and on day +9 after ICE. A platelet count of > or =20.000/microL was reached on day +12 after melphalan and on day +11 after ICE. Thus, combining positive and negative purging is feasible, further enhances purging efficiency, and does not compromise the quality of the graft, leading to rapid engraftment after high-dose chemotherapy.

[Chondrocalcinosis (pseudogout) of the meniscus]

Among 1060 histologically examined meniscus cartilages from patients aged 11--74 years 20 (2%) had chondrocalcinosis. Age at onset of symptoms was 28--67 years, duration of symptoms until surgical removal of the meniscus six weeks to 20 years. All patients had pain, 12 had pain-independent limitations of knee movement. Effusions of the knee were present in ten. Independent of the radiological findings, in the majority of patients the symptoms were markedly improved or completely absent one-two years after meniscus removal. All meniscus specimens revealed severe changes both macroscopically and histologically. The clinical diagnosis confirmed by demonstrating calcium pyrophosphate crystals in haemalauneosin stained sections, examined by polarisation microscopy. The X-ray films demonstrated arthrosis in at least 50% of cases. There appeared to be a close mutual relationship between chondrocalcinosis and arthrosis of the knee-joint.