Selinexor-based regimens in patients with multiple myeloma after prior anti-B-cell maturation antigen treatment

There is a lack of consensus on therapy sequencing in previously treated multiple myeloma, particularly after anti-B-cell maturation antigen (BCMA) therapy. Earlier reports on selinexor (X) regimens demonstrated considerable efficacy in early treatment, and after anti-BCMA-targeted chimeric antigen receptor-T cell therapy. Here, we present data from 11 heavily pretreated patients who predominantly received BCMA-antibody-drug conjugate therapy. We observe that X-containing regimens are potent and achieve durable responses with numerically higher overall response and clinical benefit rates, as well as median progression free survival compared to patients' prior anti-BCMA therapies, despite being used later in the treatment course. In an area of evolving unmet need, these data reaffirm the efficacy of X-based regimens following broader anti-BCMA therapy.

Selinexor in Advanced, Metastatic Dedifferentiated Liposarcoma: A Multinational, Randomized, Double-Blind, Placebo-Controlled Trial

PURPOSE

Antitumor activity in preclinical models and a phase I study of patients with dedifferentiated liposarcoma (DD-LPS) was observed with selinexor. We evaluated the clinical benefit of selinexor in patients with previously treated DD-LPS whose sarcoma progressed on approved agents.

METHODS

SEAL was a phase II-III, multicenter, randomized, double-blind, placebo-controlled study. Patients age 12 years or older with advanced DD-LPS who had received two-five lines of therapy were randomly assigned (2:1) to selinexor (60 mg) or placebo twice weekly in 6-week cycles (crossover permitted). The primary end point was progression-free survival (PFS). Patients who received at least one dose of study treatment were included for safety analysis (ClinicalTrials.gov identifier: NCT02606461).

RESULTS

Two hundred eighty-five patients were enrolled (selinexor, n = 188; placebo, n = 97). PFS was significantly longer with selinexor versus placebo: hazard ratio (HR) 0.70 (95% CI, 0.52 to 0.95; one-sided P = .011; medians 2.8 v 2.1 months), as was time to next treatment: HR 0.50 (95% CI, 0.37 to 0.66; one-sided P < .0001; medians 5.8 v 3.2 months). With crossover, no difference was observed in overall survival. The most common treatment-emergent adverse events of any grade versus grade 3 or 4 with selinexor were nausea (151 [80.7%] v 11 [5.9]), decreased appetite (113 [60.4%] v 14 [7.5%]), and fatigue (96 [51.3%] v 12 [6.4%]). Four (2.1%) and three (3.1%) patients died in the selinexor and placebo arms, respectively. Exploratory RNA sequencing analysis identified that the absence of CALB1 expression was associated with longer PFS with selinexor compared with placebo (median 6.9 v 2.2 months; HR, 0.19; P = .001).

CONCLUSION

Patients with advanced, refractory DD-LPS showed improved PFS and time to next treatment with selinexor compared with placebo. Supportive care and dose reductions mitigated side effects of selinexor. Prospective validation of CALB1 expression as a predictive biomarker for selinexor in DD-LPS is warranted.

Digital monitoring and assessments in patients with glioblastoma

2045

Background: Glioblastoma (GBM) is an aggressive primary tumor with poor prognosis and survival. Patients (pts) experience debilitating symptoms that have a negative effect on quality of life (QoL). A multidisciplinary approach is necessary to facilitate the reduction of morbidity, preserve QoL, and maximize benefits of treatment. Selinexor (SEL) is a first-in class, oral, selective inhibitor of nuclear export that blocks exportin 1 approved for use in multiple myeloma and diffuse large B-cell lymphoma and has shown activity in GBM. Digital measurements in the KING study through wearable sensors and other devices capture actionable daily data at home for improved care, symptom management, and QoL, are reported here. Methods: XPORT-GBM-029 (NCT04421378) is an ongoing phase 1 dose finding study followed by an open-label randomized phase 2, 5-arm trial to evaluate SEL in combination with standard therapies for newly diagnosed and recurrent GBM (n = 350): radiation+SEL /radiation and temozolomide; radiation and temozolomide±SEL; lomustine±SEL; bevacizumab±SEL; tumor treating field±SEL. The study is conducted at 18 sites in the US and Canada. GBM progression is assessed by standard clinical and imaging as well as QoL measurements by novel digital tools. Four parameters to determine the impact on QoL (cognitive function, lateralization, fatigue, sleep) are measured remotely by smartwatch and smartphone to continuously measure activity and sleep, and to complete a cognitive battery at baseline and before each MRI. Results: To date, pts wearing the smartwatch had higher compliance during the day for activity and gait measures compared to night for sleep measures. Younger pts had better compliance. Over the course of SEL treatment, changes were observed in balance (characterized by double support % and walking asymmetry) and activity level (characterized by step count and walking distance). Of the pts who participated in the cognitive battery (CANTAB) tests, 2 pts had a minor change in cognition measures including psychomotor and processing speed, episodic and spatial working memory, and executive function after 2 SEL treatment cycles. Overall, the CANTAB measures are stable, which align with the mRANO (MRI) results. The correlation between the CANTAB cognition measures and MRI data will be evaluated once more clinical data become available. Ongoing analyses will apply machine learning and statistical tools to determine potential correlations between digital and clinical data, such as physical examinations, AEs, Karnofsky scores, mRANO, NANO, KPS, and PRO QoL questionnaires. Conclusions: This is the first demonstration of digital measurement feasibility in a longitudinal study of pts with GBM. Digital measurements for pts with GBM could provide information on the impact of SEL-based treatment and functional outcomes in clinical trials and increase communication between clinicians and pts, thereby improving QoL and care management. Clinical trial information: NCT04421378.

Safety and Efficacy of Combination Maintenance Therapy with Ixazomib and Lenalidomide in Patients with Posttransplant Myeloma

PURPOSE

In this study, the addition of ixazomib to lenalidomide maintenance post-autologous stem cell transplant (ASCT) in 64 patients with newly diagnosed multiple myeloma was evaluated on the basis of the observed benefit of lenalidomide-only maintenance in prior studies.

PATIENTS AND METHODS

Patients were started on maintenance therapy with lenalidomide and ixazomib within 60-180 days of stem cell infusion.

RESULTS

Response rates deepened over time from baseline post-ASCT for 39 patients. The complete response (CR)/stringent CR rate was 43% and median overall survival was not reached with a median follow-up of 62 months (range, 25-82 months). Median PFS (mPFS) for all patients was 73 months and has not been reached for those with International Staging System (ISS) stage 1 disease. mPFS in 9 patients who had ISS stage 3 disease and 14 patients who had high-risk cytogenetics was 34 and 25 months, respectively. Twenty-two patients had progressive disease, while 19 patients continue to receive dual maintenance. The most common grade 3/4 adverse events included neutropenia, leukopenia, thrombocytopenia, lung infections, diarrhea, and maculopapular rash. Second primary malignancies occurred in 9 patients. Toxicity led to dose reductions in ixazomib and lenalidomide in 20 and 31 patients, respectively. Discontinuation of ixazomib due to toxicity occurred in 4 patients. Grade 1/2 neuropathy occurred in 22 patients and led to reduction or discontinuation of ixazomib in 2 patients.

CONCLUSIONS

The addition of ixazomib to lenalidomide maintenance demonstrated a better than expected PFS compared with historical data using lenalidomide alone and was safe and tolerable.

Open-label phase 1/2 study evaluating the tolerability and antitumor activity of selinexor and pembrolizumab in colorectal cancer

110

Background: Single agent selinexor, an oral selective inhibitor of nuclear export (SINE), showed activity against heavily pretreated CRC with RAS mutations (mut) or wildtype (wt) in 2 clinical studies. In preclinical studies, selinexor showed superior potency in KRAS mut over wt with improved activity in combination with PD-1/PD-L1 blockade. A phase 1b study (NCT02419495) showed the safety and antitumor activity of combined selinexor and a PD-1/PD-L1 inhibitor. This phase 1/2 open-label study is evaluating selinexor with pembrolizumab in patients with microsatellite instability (MSI)-stable CRC. Methods: The study enrolled patients with advanced/metastatic CRC who progressed after prior chemotherapy (1-3 lines for RAS wt, 1-2 for RAS mut) and are ineligible for anti-PD-1/PD-L1 therapy. Patients received weekly oral selinexor 80 mg and pembrolizumab 200 mg IV every 3 weeks. Antitumor activity, safety and tolerability were assessed. Results: Thirty-four patients, median age 57.5 years, male 59%, RAS mut 53%, median prior lines 2, are enrolled. At data cutoff (1-SEP-21) median treatment duration was 57 days (range: 1-246) and 25 patients were evaluable for response. Best response was stable disease in 8/13 patients with RAS mut CRC (62%) and in 3/12 patients with RAS wt CRC (25%). Median overall survival (months) has not been reached for the overall population (95% CI: 6.3, NE), for RAS mut (95% CI: 7.6, NE), and for the RAS wt (95% CI: 6.1, NE). Median progression-free survival is 3.0 and 1.4 months for patients with CRC with RAS mut and wt, respectively (p=0.04; HR: 0.43 [959% CI: 0.18, 1.01]). Thirty patients (88%) discontinued therapy, mostly due to progressive disease (44%). The most common treatment-emergent adverse events (TEAEs) (total; Grade ≥3) were nausea (77%; 3%), vomiting (41%; 0%), fatigue (41%; 12%), decreased appetite (35%; 0%), diarrhea (32%; 0%). Nine patients (26%) had serious treatment-emergent adverse events. Conclusions: Combined selinexor with pembrolizumab demonstrated higher disease control rates and prolonged overall survival in patients with chemotherapy-refractory advanced/metastatic CRC with RAS mut vs RAS wt tumors. These patients would not have been eligible for anti-PD-1 mAb therapy because their tumors were not MSI-high, suggesting that the combination may be active in RAS mut CRC. Therapy was well tolerated with no unanticipated adverse events. Further investigation of this combined treatment is warranted, particularly in patients with CRC with RAS mut. Clinical trial information: NCT04256707.

SIENDO/ENGOT-EN5/GOG-3055: A randomized phase 3 trial of maintenance selinexor versus placebo after combination platinum-based chemotherapy in advanced or recurrent endometrial cancer

TPS5610

Background: Endometrial cancer (EC) is the most common gynecologic malignancy. Options for advanced or recurrent EC following platinum-based therapy and/or radiotherapy are limited and prognosis remains poor. Selinexor is a novel, oral selective inhibitor of nuclear export (SINE) which forces nuclear retention and activation of tumor suppressor proteins. Selinexor in combination with low dose dexamethasone is approved for relapsed/refractory multiple myeloma. In addition, selinexor monotherapy has demonstrated broad activity in other hematologic malignancies and solid tumors. In a phase 2 study, 50 mg/m2 (̃80 mg) selinexor administered twice weekly demonstrated a disease control rate ( SD ≥ 12 weeks or a PR) of 35% with 2 confirmed partial responses among 23 heavily pretreated EC patients); similar results were observed in 60 pts with platinum resistant or refractory ovarian cancer (median 5 prior regimens, ORR 8%, DCR 30%) (Vergote I et al. Gynecol Oncol 2020). In the absence of approved maintenance therapies, we conducted this study to evaluate the efficacy of selinexor compared with placebo as maintenance therapy in patients with advanced or recurrent EC following platinum-based chemotherapy. Methods: This is a multicenter, double-blind, placebo-controlled, randomized phase 3 study in patients in partial (PR) or complete remission (CR) after completing at least 12 weeks of taxane-platinum combination therapy for primary Stage IV disease and recurrent disease (i.e., relapse after primary therapy for early stage disease including surgery and/or adjuvant therapy). A total of 248 patients will be enrolled at 80 sites in Europe, North America, and Israel. Patients will be randomized in a 2:1 ratio to either maintenance therapy with 80 mg oral selinexor once weekly or placebo. Stratification factors include primary Stage IV versus first recurrence at the time of taxane-platinum therapy and disease status after chemotherapy (PR vs CR). Treatment will continue until disease progression. The primary endpoint is progression free survival (PFS) per RECIST v1.1. Secondary endpoints include disease-specific survival, overall survival, time to first subsequent therapy, time to second subsequent therapy, PFS on subsequent therapy and safety and tolerability. The study is currently open and enrolling patients. Clinical trial information: NCT03555422.

Survival among older patients with previously treated multiple myeloma treated with selinexor, bortezomib, and dexamethasone (XVd) in the BOSTON study

8019

Background: Multiple myeloma (MM) typically affects older populations, which are more vulnerable to toxicity with anti-MM treatments. These patients (pts) have significant morbidity and mortality, resulting in a need for dose modifications or alternative suboptimal treatment options. Significant improvements were observed in the BOSTON study with XVd vs Vd in median progression-free survival (PFS), overall response rate (ORR), and rates of peripheral neuropathy (PN); median overall survival (OS) trended in favor of XVd. Methods: The phase 3 randomized BOSTON trial (NCT03110562) is a controlled, open-label study of once weekly XVd vs. twice weekly standard Vd in pts with MM and 1-3 prior treatment regimens. We performed post-hoc analyses to compare survival benefits in pts ≥65 vs < 65 years of age. Results: The BOSTON study enrolled a total of 402 pts between June 2017 and February 2019 that were randomized into XVd or Vd arms. The numbers of pts treated with XVd or Vd who were ≥65 were 109/132 and 86/75 who were < 65, respectively. Baseline characteristics were similar by age although pts ≥65 years were less likely to have received ASCT than those < 65 years (48.4% vs. 25.3%). Median PFS was prolonged with XVd compared with Vd, across both age groups: ≥65 (HR, 0.55 [95% CI, 0.37-0.83] P = 0.002) and < 65, (HR, 0. 74 [95% CI, 0.49-1.11], P = 0.07). Vd was associated with a lower ORR (64.4%) than treatment with XVd (76.1%) (OR, 1.77 [95% CI, 1.00-3.11], P = 0.024) in pts ≥65, while the ORR in those < 65 was 76.7% with XVd and 58.7% (OR, 2.33 [95% CI, 1.18-4.59], P = 0.007) with Vd. As of Jan 2021, the median OS for the overall population was not reached for both arms (HR = 0.86; p = 0.193), with 61 and 75 deaths in the XVd and Vd arms, respectively. Median OS was not reached in pts ≥65 with XVd and was 28.6 months with Vd (HR = 0.60; 95% CI, 0.38-0.94; p = 0.012), while there was no difference in the OS for pts < 65 (HR = 1.52; 95% CI, 0.86-2.68; p = 0.926). Pts ≥65 had a lower incidence of death with XVd as compared to Vd (29 vs 56) and there were 32 deaths with XVd and 19 with Vd in pts < 65. Grade ≥3 treatment-emergent adverse events were not observed more often in older compared to younger pts. Amongst pts ≥65, PN of any grade was lower with XVd (32.1%) compared to Vd (46.5%); (OR 0.57 [95% CI 0.34-0.97], p = 0.017), including a lower incidence of grade ≥3 PN (XVd 4.6% vs. Vd 11.6%). Pts < 65 followed a similar trend of PN AEs of any grade: XVd, 32.6%; Vd, 48.0% (OR 0.42 [95% CI 0.21-0.82], p = 0.006). Conclusions: In an older patient population with a poor prognosis, XVd was associated with a significant survival benefit, improved PFS and OR with reduced PN, and requires relatively short and infrequent clinic visits. XVd may be a simple, effective regimen for pts ≥65 years of age. Clinical trial information: NCT03110562.

Updated overall survival of eltanexor for the treatment of patients with hypomethylating agent refractory myelodysplastic syndrome

e19037

Background: Patients (pts) with myelodysplastic syndrome (MDS) refractory to hypomethylating agents (HMAs) have limited therapeutic options and a dismal prognosis with a median overall survival (mOS) of 4-6 months. Eltanexor (ELTA) is a second-generation, oral, selective inhibitor of nuclear export (SINE) compound that showed anti-tumor activity and lower brain penetration compared to selinexor (SEL) in nonclinical models. It was hypothesized that ELTA could be dosed more frequently than SEL with a lower incidence of centrally mediated nausea. Early results from a phase 1/2 study of ELTA in pts with HMA refractory MDS showed anti-tumor activity with marrow complete response (mCR) and stable disease (SD); side effects were primarily low-grade, dose-dependent, and reversible (Lee et al. ASH 2019). In this abstract, we provide a subgroup analysis of the efficacy evaluable population with an update on mOS in the same population. Methods: This phase 1/2 study (NCT02649790) evaluated single-agent ELTA in pts with higher-risk MDS, ie, high-risk or intermediate-2 MDS by International Prognostic Scoring System (IPSS) and 5%-19% myeloblasts. Out of 20 pts enrolled, 15 pts were evaluable for efficacy and constitute the population studied in this analysis. Two doses of ELTA were evaluated: 10 mg (n=5) or 20 mg (n=15) every day for 5 days per week of a 28-day cycle. Results: As of 1 Feb 2021, the 15 pts evaluable for efficacy (median age 76 years; range 62-89) had a median of 2 prior treatment regimens (range 1-4); 93% had high/int-2 risk per IPSS. Of the 20 enrolled patients, 7 (35%) had mCR, and 5 (25%) had SD for a total disease control (mCR+SD) rate of 60%. Of the 15 pts evaluable for efficacy, 7 (47%) had mCR and 5 (33%) had SD. In the 10-mg cohort (n=5), all pts derived clinical benefit with 3 pts (60%) reaching mCR and 2 pts (40%) SD. In the 20-mg cohort (n=10), 4 pts (40%) had mCR and 3 (30%) had SD. Four pts had hematologic improvement (HI) and became transfusion independent for at least 8 weeks including 2 pts with tri-lineage HI. OS for pts who reached mCR (n=7) was significantly longer than for pts who did not reach mCR (n=8): median 11.86 vs 8.67 months (mo) (hazard ratio [HR]=0.27, p=0.05), and significantly longer than OS for pts with PD (n=3, mOS=3.15 mo, HR=0.23, p=0.04). Pts with disease control (n=12) had numerically longer mOS than pts with PD (9.86 vs 3.15 mo, HR=0.38, p=0.09). Pts with HI had a mOS of 10.58 months. Conclusions: Single-agent oral ELTA was active in pts with high-risk, HMA refractory MDS. Pts with mCR had significantly longer mOS than pts without mCR or with PD. Further evaluation of ELTA in MDS as a single agent and in combination with other agents is ongoing. Clinical trial information: NCT02649790.

Molecular predictors of response to selinexor in advanced unresectable de-differentiated liposarcoma (DDLS)

11509

Background: Patients (pts) with recurrent inoperative DDLS have a poor prognosis and limited treatment options. Selinexor is an oral, selective inhibitor of nuclear export (SINE) compound approved for previously treated pts with myeloma and diffuse large B-cell lymphoma. SEAL was a Phase 2-3 randomized, double-blind, study of selinexor versus placebo in pts with progressive DDLS and 2-5 prior systemic therapies. SEAL showed significantly prolonged progression-free survival (PFS, HR = 0.70, p = 0.0228) with well managed toxicity. A biomarker predictive of clinical activity could be used to optimize selection of pts with DDLS for selinexor. Methods: Pts were randomized 2:1 for Phase 3: 188 received twice weekly selinexor (60mg) and 97 received placebo. Three exploratory biomarker analyses (RNA sequencing of biopsies) from selinexor-treated pts were performed: discovery set of sensitive (n = 8) or resistant (n = 9) tumors; a validation set of pts with favorable (n = 19) or poor (n = 14) tumor control based on PFS, and paired lesions from a pt who harbored both a responsive and resistant lesion. Tumor biopsies from 24 pts on placebo with short ( < 5 months, n = 18) and long ( > 6 months, n = 6) PFS were RNA sequenced. Gene expressions were compared using a negative binomial distribution with DeSeq2. Pathway analyses were performed using Gene Set Enrichment Analysis (GSEA) with MSigDB Cancer Gene Neighborhoods. Results: RNA sequencing analysis comparing 17 sensitive and resistant tumors identified 114 differentially expressed genes (adjusted p-values < 0.05). Expression of CALB1, which encodes the calcium-binding protein calbindin, was significantly lower in sensitive tumors (adjusted P [Padj] = 7.5x10-20), and expression of GRM1, which encodes a metabotropic glutamate receptor that activates phospholipase C, was higher in selinexor sensitive tumors (Padj= 0.003). These findings were confirmed in an independent validation set (Padj = 0.01 – 0.02). In the pt with paired sensitive and resistant lesions, CALB1 expression was 52-fold lower in the sensitive tumor. In a comparison of placebo-treated pts, neither CALB1 or GRM1 was differentially expressed between pts with short or long PFS, indicating they are markers of response to selinexor treatment, rather than general markers of disease aggressiveness. Gene set enrichment analyses revealed that selinexor sensitive tumors in the discovery and validation sets showed upregulation of cancer genes related to SNRK and the netrin 1 receptor tumor suppressor DCC. The resistant tumors showed upregulated EIF3S2 translation initiator-related genes. Conclusions: Selinexor sensitive DDLS tumors showed low expression of CALB1 and high GRM1. If validated, pts with DDLS whose tumors match this expression profile are especially likely to benefit from selinexor. Clinical trial information: NCT02606461.

Selinexor in combination with weekly paclitaxel in patients with advanced or metastatic solid tumors: Results of an open label, single-center, multiarm phase 1b study

5565

Background: Selinexor is a first-in-class novel, oral potent selective inhibitor of nuclear export (SINE) which blocks Exportin-1 (XPO1) leading to nuclear accumulation and activation of tumor suppressor proteins and prevention of translation of proto-oncogenes. Weekly paclitaxel is a standard chemotherapy regimen used in various tumor types. Preclinical models show that selinexor with paclitaxel exerts antitumor activity against multiple solid tumors. Our objective was to determine the maximum tolerated dose (MTD) and recommended phase II dose (RP2D) of selinexor and weekly paclitaxel. Methods: This was an open label, single-center, multi-arm phase 1b study utilizing a “3 + 3” design and a “basket type” expansion. Selinexor (twice weekly orally) and weekly paclitaxel (80mg IV 2 week on, 1 week off) was employed as one of 13 parallel arms. Two dose levels (DL) of selinexor were explored: DL1 selinexor 60mg; DL2 selinexor 80mg. Patients (pts) with advanced or metastatic solid tumors were eligible if they had adequate bone marrow and organ function. There was no limit on prior lines of therapy. Efficacy was evaluated using RECIST 1.1. Progression free survival (PFS) was defined as time from treatment until disease progression or death. Results: Of 35 pts treated, all were evaluable for toxicity, and 31 (88%) were evaluable for response. Pt diagnoses included ovarian (n = 28), breast (n = 4), prostate (n = 2), and cervical (n = 1) cancer. Pts had a median of four prior therapies (range 1-10), and 47% had a prior taxane. All pts with ovarian cancer had platinum resistant/refractory disease; high grade serous histology was most common. There were no DLTs and DL1 was chosen as the RP2D given its long term tolerability. 97% of pts had at least one treatment-emergent adverse event (TEAE) and the most common TEAEs were anemia (74%), nausea (57%), fatigue (51%), leukopenia (51%), neutropenia (49%), thrombocytopenia (46%), and vomiting (31%). The most prevalent grade ≥ 3 TEAE were neutropenia (46%), anemia (31%), leukopenia (17%), and fatigue (9 %). Partial responses (PR) were noted in 4 pts (13%); 10 pts (32%) achieved stable disease for > 4 months for a clinical benefit rate (CBR) of 45%. 16 pts (47%) had prior exposure to a taxane, including 1 pt who achieved PR. Among 24 evaluable pts with ovarian cancer, response rate was 17%, CBR was 58%, and PFS was 6.83 months (95% CI 3.73, not reached (NR)). Median duration of clinical benefit in ovarian cancer was 7.57 months (95% CI: 4.43, NR). Conclusions: Oral selinexor in combination with weekly paclitaxel demonstrated promising clinical activity with manageable toxicity, and further evaluation with once weekly selinexor is warranted. This combination should be considered for further exploration in a randomized study, especially in ovarian malignancies. Clinical trial information: NCT02419495.

Effects of weekly selinexor, bortezomib, dexamethasone (XVd) versus standard twice weekly bortezomib and dexamethasone (Vd) on RAS-mutated previously treated multiple myeloma (MM)

8027

Background: Activating mutations of the RAS genes NRAS, KRAS, and HRAS ( RASmut) occur in up to 50% of MM and portend poor survival and high recurrence rates. MM cells with RASmut are susceptible to inhibition of germinal center kinase (GCK), resulting in IKAROS degradation independent of cereblon (CRBN). Selinexor is a selective inhibitor of nuclear export (SINE) compound that can induce IKAROS degradation through CRBN-independent pathways to overcome immunomodulatory drug resistance. We explored the benefit of selinexor treatment for pts with RASmut MM. Methods: In the randomized BOSTON study, pts with MM after 1-3 therapies received weekly XVd or twice weekly Vd. In the single-arm STORM study pts with penta-treated, triple class refractory MM were treated with twice weekly Xd. Both treatment regimens are now FDA approved. Mutations were assessed post-hoc by exome sequencing of 119 and 52 pts from BOSTON and STORM, respectively. Pts were considered RASmut if their MM had NRAS, KRAS or HRAS mutations in codons 12, 13 or 61. Results: There were 54 pts (45%) with RASmut in BOSTON (XVd = 26, Vd = 28), and 17 (33%) in STORM. In BOSTON, pts with RASmut MM treated with XVd had significantly longer progression-free survival (PFS) than those treated with Vd (median [med] = 12.9 vs 6.7 months [mo], hazard ratio [HR] = 0.48 [95% CI 0.24-0.97], p = 0.039). For pts treated with Vd, those with RASmut had significantly shorter overall survival (OS) compared to RASwild-type (WT) (med = 16.8 mo vs not reached [NR], HR = 2.87 [95% CI 1.03-7.99], p = 0.035). PFS was not significantly different (med = 6.74 vs 9.82 mo, HR = 1.64 [95% CI 0.88-3.07], p = 0.122). Amongst pts on XVd, there was no difference in survival between RASmut and RASWT pts (PFS: med = 12.8 vs 12.9 mo, HR = 1.08 [95% CI 0.52-2.26], p = 0.83; OS: med = NR vs NR, HR = 0.94 [95% CI 0.36-2.45], p = 0.91). In STORM, pts with RASmut had shorter OS compared to RASwt pts (med = 6.1 vs NR, HR = 2.05 [95% CI 1.22-5.19], p = 0.010). Preliminary studies to explore the mechanisms of action related to RASmut MM sensitivity to XVd demonstrated that selinexor treatment in vitro leads to downregulation of GCK. Conclusions: Despite typically having the worst outcomes, pts with RASmut MM had a similar benefit from XVd as RASWT MM, showing that the XVd combination can overcome RASmut. Mechanistically, selinexor induced down regulation of GCK and enhanced killing of RASmut MM cells. With a manageable safety profile, the XVd regimen could provide a viable treatment option to improve survival of pts with MM with RAS mutations. Clinical trial information: NCT03110562. [Table: see text]

Effects of refractory status to lenalidomide on safety and efficacy of selinexor, bortezomib, and dexamethasone (XVd) versus bortezomib and dexamethasone (Vd) in patients with previously treated multiple myeloma

8024

Background: Lenalidomide (LEN) is typically a frontline therapy for newly diagnosed MM. Patients (pts) with MM refractory to LEN are less likely to repond to other IMiDs and represent a signification area of unmet medical need. In the BOSTON study in the ITT population, XVd was associated with significant improvements in median progression-free survival (PFS), overall response rate (ORR), and rates of peripheral neuropathy, with trends in overall survival (OS) favoring XVd. Methods: The BOSTON trial (NCT03110562) is a Phase 3 randomized, controlled, open-label study of once weekly XVd vs twice weekly Vd in pts with MM and 1-3 prior therapies. We performed post-hoc analyses on two different subgroups to compare outcomes based on refractory status to LEN and immunomodulatory drug (IMiD) therapy. These post hoc analyses evaluated if PFS, overall response rate (ORR), time to next treatment (TTNT) and safety was influenced by prior treatment with LEN when comparing XVd with Vd. Results: Amongst the 402 pts in BOSTON, 160 had MM refractory to any IMiD (XVd = 74, Vd = 86). Of those, 106 were documented to be refractory to LEN (XVd = 53, Vd = 53) and 296 were not refractory to LEN (XVd = 142, Vd = 154). Baseline characteristics were generally well balanced between subgroups. In these subgroups based on refractory status to IMiD or LEN, median PFS was significantly longer in the XVd arm as compared to Vd (IMiD refractory, 13.9 vs. 8.4 months (mo), p = 0.005; LEN refractory, 10.2 vs. 7.1 mo, p = 0.012; not LEN refractory, 15.4 vs 9.6 mo, p = 0.014). Significant increases in TTNT were observed with XVd treatment in pts that were IMiD refractory (14.8 vs. 10.2 mo, p = 0.003), LEN refractory (13.0 vs. 7.6 mo, p = 0.015), and not refractory to LEN (19.1 vs 12.9 mo, p = 0.005). ORR was improved with XVd compared to Vd regardless of refractory status (IMiD refractory, 68.9% vs 55.8%, p = 0.045; LEN refractory, 67.9% vs. 47.2%, p = 0.016; and not refractory to LEN, 79.6% vs 67.5%, p = 0.010). The most common treatment-emergent AEs for the XVd/Vd arms for all subgroups were thrombocytopenia (66.2/30.6%; 71.7/40.4%; 55.6/22.4%), nausea (48.6/11.8%; 50.9/11.5%; 50.0/9.2%), and fatigue (40.5/20.0%; 45.3/21.2%; 40.8/17.1%) for IMiD, LEN, and not LEN refractory, respectively. Incidence of PN AEs of any grade were reduced compared to pts treated with Vd (IMiD refractory, 27% vs. 42.4%; LEN refractory, 30.2% vs 36.5%; not refractory, LEN 33.1% vs 50.7%). Conclusions: In pts with previously treated MM, PFS, ORR, and TTNT were significantly improved regardless of documented refractory status to any IMiD or to LEN-specifically. These analyses support the use of the XVd combination for pts with disease refractory to LEN and likely to any IMiD. Clinical trial information: NCT03110562.

Open-label phase 1 study evaluating the tolerability and anti-tumor activity of selinexor and pembrolizumab in colorectal cancer

e15579

Background: Colorectal cancer (CRC) is the fourth leading cause of cancer-related deaths worldwide and is heterogenous in its molecular features. Checkpoint inhibitors (CPIs) are approved for only about 5% of unresectable or metastatic CRC with MSI-high (MSI-H)/deficient MMR (dMMR); however, they do not benefit the majority of advanced CRC patients. Selinexor is a first-in-class, oral selective inhibitor of nuclear export (SINE) compound with demonstrated activity in cancers with RAS mutations which are found in ̃50% of CRC. This study aims to evaluate the combination of selinexor with pembrolizumab, an anti-PD-L1 CPI, in chemotherapy refractory CRC. Methods: This phase 1/2, open-label study enrolled patients with advanced/metastatic CRC with progression after prior chemotherapy (1-3 lines for KRAS wild-type (wt), 1-2 for KRAS mutant (mut)), initially into a selinexor monotherapy period to evaluate bioavailability/bioequivalence of a new selinexor formulation, followed by a combination therapy where patients were treated with selinexor 80 mg PO QW and pembrolizumab 200 mg IV every 3 weeks. Patients were assessed for anti-tumor activity, safety, and tolerability of the combination therapy. Results: Enrollment in this study has been completed, and 29 patients have received at least 1 dose of combination therapy: median age was 56 years, 19 (65.5%) male, and 15 (51.7%) have RAS mutations. Median number of lines of prior antineoplastic therapies was 2. Median duration of combination treatment is 39 days (range: 1-246 days). Seventeen patients (58.6%) discontinued therapy mostly due to progressive disease, and 18 patients are evaluable for response. Best response was stable disease in 7 patients (6 of them (85.7%) had RAS mut CRC), and progressive disease in 11 patients (8 of them (72.7%) had RAS wt CRC. Median progression free survival (PFS) is 120 days for patients with RAS mut CRC and 41 days for those with RAS wt CRC. Notably, none of the RAS mut had MSI-H/dMMR CRC while one RAS wt with SD had MSI-H/dMMR CRC. The most common treatment-emergent adverse events (total; ≥Grade 3) were nausea (72.4%; 0%), vomiting (41.4%; 0%), decreased appetite (34.5%; 0%), and fatigue (34.5%; 10.3%). Seven patients (24.1%) had at least 1 treatment-emergent serious adverse event. Conclusions: Selinexor in combination with pembrolizumab has demonstrated disease control in patients with chemotherapy refractory advanced/metastatic CRC. Greater anti-tumor activity was observed in patients with RAS mutations despite absence of MSI-H/dMMR. The therapy was well tolerated with no unanticipated adverse events observed. These results warrant further investigation of selinexor in combination with pembrolizumab in CRC, particularly in CRC with RAS mutations. Clinical trial information: NCT04256707.

Digital measurement of functional status of patients with glioblastoma

2016

Background: Among the primary aims of new therapies for glioblastoma (GBM) are the reduction of morbidity and restoration or preservation of quality of life (QoL). Selinexor (SEL) is a first-in class, oral, selective inhibitor of nuclear export which blocks exportin 1 (XPO1), forcing the nuclear retention and reactivation of tumor suppressor proteins, ultimately causing cell death in cancer cells. SEL is approved for the treatment of previously treated multiple myeloma and DLBCL. XPORT-GBM-029 (NCT04421378) is a phase 1 dose finding study followed by an open-label randomized phase 2, 3-arm trial to evaluate SEL in combination with standard therapies for newly diagnosed and recurrent GBM: Arm A (ndGBM, uMGMT) – radiation +/- SEL; Arm B (ndGBM, mMGMT) – radiation and temozolomide +/- SEL; Arm C (rGBM) – lomustine +/- SEL at first relapse. We look to identify sensitive, reliable, and clinically meaningful digital assessments of the functional status of ndGBM and rGBM patients via a patient-centric approach. Methods: XPORT-GBM-029 incorporates standard clinical and imaging evaluations of GBM progression with novel digital tools that objectively measure motor and cognitive function. The study is conducted at 50 sites globally with the aim of enrolling 350 patients with newly diagnosed and recurrent GBM. Following discussions with KOLs and patient advocacy partners at EndbrainCancer, we surveyed GBM patients and their caregivers to identify disease manifestations critical to patients’ QoL. The survey revealed four key areas impacting patients’ QoL that can be affected by GBM therapies and can be objectively monitored: cognitive function, lateralization, fatigue, and sleep. In this trial we use objective measurements to evaluate SEL’s effects on GBM patients’ QoL. Patients wear inertial sensors to measure their activity and sleep and complete a cognitive battery at baseline and before each MRI. Results: Associations between objective digital measures of activity, gait, fatigue, sleep, and cognition will be examined with respect to clinical assessments including physical examinations, modified Response Assessment in Neuro-Oncology (mRANO), Neurologic Assessment in Neuro-Oncology (NANO), Karnofsky Performance Score (KPS) and Patient Reported Outcome (PRO) QoL questionnaires. Descriptive summary statistics and plots are employed in exploratory data analysis, and other advanced data mining methods may also be considered. Conclusions: XPORT-GBM-029 trial is probably the first large, prospective, longitudinal study in GBM patients employing digital markers and may provide useful information regarding the utility of wearable and mobile devices for measuring functional outcomes in clinical trials. Clinical trial information: NCT04421378.

Phase 1 Trial Evaluating Vorinostat Plus Bortezomib, Lenalidomide, and Dexamethasone in Patients With Newly Diagnosed Multiple Myeloma

INTRODUCTION

Bortezomib plus lenalidomide and dexamethasone (VRD) is a standard induction therapy for newly diagnosed multiple myeloma (NDMM) patients. Given preclinical and clinical data suggesting the synergistic activity of the histone deacetylase inhibitor vorinostat with both bortezomib and lenalidomide for the treatment of multiple myeloma, we hypothesized that adding vorinostat to VRD (R2V2) would increase the rate and the quality of responses to induction treatment. Here we report the results of a phase 1 trial (NCT01038388) evaluating R2V2 as up-front treatment for NDMM patients.

PATIENTS AND METHODS

R2V2 was tested as induction therapy in a dose-escalation phase 1 study in 30 NDMM patients deemed eligible for autologous stem-cell transplantation. Treatment consisted of 4 induction cycles with R2V2, followed by either autologous stem-cell transplantation or 4 additional R2V2 cycles and lenalidomide maintenance therapy.

RESULTS

The maximum tolerated dose of vorinostat was 200 mg daily. The most common adverse events were gastrointestinal (87%), fatigue and peripheral neuropathy (60%), and thrombocytopenia (33%). R2V2 induced an objective response in 96% of patients, with 48% obtaining at least a complete remission. Median progression-free survival was 52 months, with 77% of patients alive at 5 years.

CONCLUSION

R2V2 as induction treatment for NDMM patients resulted in remarkable response rates at the cost of increased toxicity.

Quality-of-life (QOL) analyses in patients with multiple myeloma: Results from the selinexor (KPT-330) treatment of refractory myeloma (STORM) phase IIb study

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Background: Selinexor, a novel oral selective inhibitor of nuclear export, was recently approved for use in relapsed/refractory multiple myeloma (MM). The efficacy and safety of selinexor and dexamethasone was evaluated in a phase 2b, single-arm, open-label, multicenter trial in patients with penta-exposed, triple-class refractory MM. Patient-reported outcomes were measured using the Functional Assessment of Cancer Therapy - Multiple Myeloma (FACT-MM) assessment. While minimal clinically important differences (MCID) have been established for other FACT scales, there is no known, validated definition of MCID for the FACT-MM. This study reports results of QoL analyses in patients with MM enrolled in the STORM phase 2b trial and examines two approaches to calculate MCID for the FACT-MM. Methods: FACT-MM data were collected at baseline, on day 1 of each 4-week cycle, and at end of treatment (EOT) during the STORM phase 2b trial. Change from baseline was analyzed for the FACT-MM total score, FACT-trial outcome index (TOI), FACT-General (FACT-G), and the MM-specific domain. Two approaches for evaluating MCID were explored: the first based on patient-reported assessment of meaningful change, defined as 10% of the instrument range (Ringash 2007), and the second based on mean baseline differences between ECOG groups (0 vs 1 to 2) based on patient level data. Additional analyses were performed to identify trends among treatment responders and non-responders, including a difference-in-difference (DID) analysis to compare changes between baseline and EOT. Results: Eighty patients had sufficient data to be included in longitudinal QOL analyses. MCID analyses demonstrated that most patients did not experience decline during the first six cycles of treatment; this pattern was consistent with MCID defined either as 10% of the instrument range (range 54% to 75% of patients), or as an ECOG-based anchor (range: 54% to 73% of patients). The DID analysis found that the mean change in QoL of non-responders decreased significantly between baseline and EOT, while responders had no significant change. This difference between responders and non-responders was significant for the FACT-G. Conclusions: Most patients did not experience QoL decline during the early cycles of selinexor treatment during the STORM 2b trial. The MCID decline, evaluated by two approaches, was greater among treatment non-responders than responders. A DID approach demonstrated greater decline between baseline and EOT for non-responders. Clinical trial information: NCT02336815.

Overall survival (OS) with oral selinexor plus low dose dexamethasone (Sd) in patients with triple class refractory-multiple myeloma (TCR-MM)

8014

Background: TCR-MM is defined as being refractory to immunomodulatory agents, proteasome inhibitors, and anti-CD38 mAbs, representing an urgent unmet medical need with a median OS of 3-5 months( Pick M et al, Eur J Haem 2018; Gandhi U et al, ASH 2018). Sd has shown a 26.2% overall response rate (ORR) in 122 patients (pts) with TCR-MM in the Phase 2b STORM study ( Chari A et al, ASH 2018). Here, we evaluate the OS of pts in the STORM study with Sd and in pts with bortezomib, carfilzomib, lenalidomide, pomalidomide, and daratumumab (“penta”)-exposed, TCR-MM from an observational cohort not receiving Sd. Methods: Data were drawn from STORM and a retrospective cohort from the nationally representative Flatiron Health Analytic Database (FHAD). All pts from both sources had penta-exposed TCR-MM. In order to align study populations, OS was evaluated in pts in STORM whose first therapy after their MM reached TCR status was Sd and in pts in the FHAD who received ≥1 therapy after their MM reached TCR status. The index date for this evaluation was the start date of treatment after their MM reached TCR status. A Cox proportional hazards regression model was performed to assess the survival impact of Sd. In STORM, ORR was assessed by an Independent Review Committee based on IMWG criteria. Results: In the FHAD, 69 pts with TCR-MM were identified. Characteristics of the two groups of pts were similar, except that pts in STORM were more heavily pretreated, had a higher frequency of high-risk MM, a longer time since initial diagnosis of MM, and higher baseline hemoglobin and platelet values. Among the 122 pts in STORM, 64 received Sd as their first therapy after their MM became TCR, and ORR was 32.8%. Among the 69 pts from FHAD, 37 received ≥1 therapy after their MM became TCR. Median OS (N = 64) was 10.4 months for pts receiving Sd in STORM and 5.2 months (N = 37) for pts not receiving Sd in FHAD (HR = 0.49, p = 0.0241). Conclusions: The prognosis of TCR-MM in the real-world population appears very poor. Within the limits of this analysis, median OS of pts receiving Sd as their first therapy after their MM becomes TCR is significantly better than those not receiving Sd, suggesting that Sd may be associated with an OS benefit in pts with TCR-MM. Clinical trial information: NCT02336815.

Population pharmacokinetics of pomalidomide in patients with relapsed or refractory multiple myeloma with various degrees of impaired renal function

Pomalidomide is an immunomodulatory drug for treatment of relapsed or refractory multiple myeloma (rrMM) in patients who often have comorbid renal conditions. To assess the impact of renal impairment on pomalidomide exposure, a population pharmacokinetics (PPK) model of pomalidomide in rrMM patients with various degrees of impaired renal function was developed. Intensive and sparse pomalidomide concentration data collected from two clinical studies in rrMM patients with normal renal function, moderately impaired renal function, severely impaired renal function not requiring dialysis, and with severely impaired renal function requiring dialysis were pooled over the dose range of 2 to 4 mg, to assess specifically the influence of the impaired renal function as a categorical variable and a continuous variable on pomalidomide clearance and plasma exposure. In addition, pomalidomide concentration data collected on dialysis days from both the withdrawal (arterial) side and from the returning (venous) side of the dialyzer, from rrMM patients with severely impaired renal function requiring dialysis, were used to assess the extent to which dialysis contributes to the removal of pomalidomide from blood circulation. PPK analyses demonstrated that moderate to severe renal impairment not requiring dialysis has no influence on pomalidomide clearance or plasma exposure, as compared to those patients with normal renal function, while pomalidomide exposure increased approximately 35% in patients with severe renal impairment requiring dialysis on nondialysis days. In addition, dialysis increased total body pomalidomide clearance from 5 L/h to 12 L/h, indicating that dialysis will significantly remove pomalidomide from the blood circulation. Thus, pomalidomide should be administered post-dialysis on the days of dialysis.

Recognition of early mortality in multiple myeloma by a prediction matrix

Early mortality (EM; death ≤ 6 months from diagnosis) has been reported in several newly diagnosed multiple myeloma (NDMM) trials. Before the era of novel agents, the incidence was 10%‐14%. Causes of death included infections/pneumonia, renal failure, refractory disease, and cardiac events. Staging systems, such as the revised International Staging System (r‐ISS), and prognostic factors including cytogenetics, lactate dehydrogenase levels, and myeloma‐specific factors, are useful to assess overall prognosis; however, they cannot predict EM. We evaluated patients treated with novel agents in the Connect MM^® Registry and identified risk factors of the EM cohort. Eligible patients were enrolled in the registry within 60 days of diagnosis. Univariate and multivariate analyses were conducted to evaluate associations between baseline characteristics and EM. Prediction matrices for EM were constructed from a logistic model. Between September 2009 and December 2011, 1493 patients were enrolled in the registry and had adequate follow‐up. Of these patients, 102 (6.8%) had EM and 1391 (93.2%) survived for > 180 days. Baseline factors significantly associated with increased EM risk included age > 75 years, higher Eastern Cooperative Oncology Group performance status, lower EQ‐5D mobility score, higher ISS stage, lower platelet count, and prior hypertension. Renal insufficiency trended toward increased EM risk. These risk factors were incorporated into a prediction matrix for EM. The EM prediction matrix uses differential weighting of risk factors to calculate EM risk in patients with NDMM. Identifying patients at risk for EM may provide new opportunities to implement patient‐specific treatment strategies to improve outcomes.

Practical Approaches to the Management of Dual Refractory Multiple Myeloma

The outcome of myeloma patients' dual refractory to lenalidomide and bortezomib is generally poor and represents a significant clinical challenge with a clear need for new therapeutic approaches. This has prompted the development of next-generation proteasome inhibitors and immunodulatory drugs (IMiDs), as well as new classes of drugs with novel mechanisms of action. As a result, several of these agents have received regulatory approval that have shown promising activity in the dual refractory setting including the second-generation proteasome inhibitor carfilzomib and third-generation IMiD pomalidomide. Moreover, the regulatory approval of several first-in-class drugs for myeloma such as the histone deacetylase (HDAC) inhibitor panobinostat and the anti-CD38 monoclonal antibody daratumumab has further broadened the therapeutic landscape for these patients. Collectively, these advances have provided new treatment strategies in dual refractory myeloma as well as important insights for the development of future studies with rationally designed drug combinations to target this challenging patient population.

A Phase 1 and 2 study of Filanesib alone and in combination with low-dose dexamethasone in relapsed/refractory multiple myeloma

BACKGROUND

Filanesib (ARRY-520) is a highly selective inhibitor of kinesin spindle protein, which has demonstrated preclinical antimyeloma activity.

METHODS

This open-label Phase 1/2 study determined the maximum tolerated dose of Filanesib administered on Days 1 and 2 of 14-Day Cycles in patients with multiple myeloma (MM) and included expansion cohorts with and without dexamethasone (40 mg/week). Patients in the dose-escalation (N = 31) and Phase 2 single-agent (N = 32) cohorts had received prior bortezomib as well as prior thalidomide and/or lenalidomide. Patients in the Phase 2 Filanesib plus dexamethasone cohort (N = 55) had received prior alkylator therapy and had disease refractory to lenalidomide, bortezomib, and dexamethasone. Prophylactic filgrastim was incorporated during dose escalation and was used throughout Phase 2.

RESULTS

Patients in each cohort had received a median of ≥6 prior therapies. The most common dose-limiting toxicities were febrile neutropenia and mucosal inflammation. In Phase 2, Grade 3 and 4 cytopenias were reported in approximately 50% of patients. Nonhematologic toxicities were infrequent. Phase 2 response rates (partial responses or better) were 16% (single agent) and 15% (Filanesib plus dexamethasone). All responding patients had low baseline levels of α1-acid glycoprotein, a potential selective biomarker.

CONCLUSIONS

Filanesib 1.50 mg/m² /day administered with prophylactic filgrastim has a manageable safety profile and encouraging activity in heavily pretreated patients This study is registered at www.clinicaltrials.gov as NCT00821249. Cancer 2017;123:4617-4630. © 2017 American Cancer Society.

Additional-structural-chromosomal aberrations are associated with inferior clinical outcome in patients with hyperdiploid multiple myeloma: a single-institution experience

Multiple myeloma is cytogenetically heterogeneous and a hyperdiploid karyotype is considered currently to have standard risk. In this study, we investigated the clinical impact of additional-structural-chromosomal aberrations assessed by chromosome analysis in 284 patients with a hyperdiploid karyotype that were subdivided into four groups based on the complexity of additional-structural-chromosomal aberrations: group 1, no additional-structural-chromosomal aberrations (n=35); group 2, one additional-structural-chromosomal aberration (n=46); group 3, two additional-structural-chromosomal aberrations (n=39); group 4, ≥three additional-structural-chromosomal aberrations (n=164). Clinicopathological data among these groups showed no differences, except patients in group 1 had higher hemoglobin (P=0.031) and albumin (P=0.045) levels. The median follow-up was 55 months (range, 3-221). The median overall survival of patients in groups 1-4 was negatively correlated with the number of the additional-structural-chromosomal aberrations: 98, 76, 61, and 48 months, respectively (P<0.0001). In group 4, CKS1B gain, RB1, or TP53 deletions had no additional impact on overall survival; however, trisomy 3 or 15 conferred a much better overall survival, and monosomy 13 and 14 predicted a worse outcome. In addition, the overall survival of patients in groups 3 and 4 was similar to a subset of high-risk multiple myeloma cases (n=21) (P=0.387). About 192 (67.6%) patients who received stem cell transplantation did not show improved overall survival compared with non-stem cell transplantation patients (n=92; P=0.142) overall; however, they did show significantly improved overall survival in patients with refractory disease in group 4 (P=0.0084). Multivariate analysis showed that two or more additional-structural-chromosomal aberrations (P<0.0001), stages (P=0.02 and P=0.002) and relapsed disease (P=0.009) negatively impacted the overall survival. We conclude that hyperdiploid karyotypes in multiple myeloma are associated with additional-structural-chromosomal aberrations and a greater number of additional-structural-chromosomal aberrations predicts poorer clinical outcome. A hyperdiploid karyotype with ≥2 additional-structural-chromosomal aberrations at chromosomal level should be considered an independent high-risk factor.

Treatment outcomes and healthcare resource utilization (HRU) in patients (Pts) with newly diagnosed multiple myeloma (NDMM) with lenalidomide (LEN) only or no maintenance: Connect MM registry

e19527

Background: Maintenance therapy (MT) post autologous stem cell transplant (ASCT) improves clinical outcomes in MM, but the effect of continued treatment on HRU is largely unknown. In the Connect MM registry, 1493 NDMM pts are enrolled in cohort 1 (Sept 2009–Dec 2011) in a mostly community setting; of pts receiving MT, 70% received LEN-only MT. The effect of LEN-only vs no MT on progression-free survival (PFS), overall survival (OS) and HRU was evaluated. Methods: Adults with NDMM who completed induction and single ASCT without subsequent consolidation and received LEN-only or no MT were compared. HRU (hospitalization, surgery/procedures, concomitant medications [growth factor, bisphosphonate, neuropathic pain medication]) was assessed from 100 days post-ASCT to end of years 1 and 2. Data cutoff was Jan 7, 2016 (median follow-up of 39.3 mo). Results: 421 pts met the analysis criteria stipulated above. Of these, 180 received LEN-only MT, and 165 did not receive MT. Median age was 60 y (range, 24-78 y); 60% were men; 86%, white. Besides serum creatinine, calculated International Staging System stage, history of monoclonal gammopathy of unknown significance, del(17p), and induction regimen, characteristics were similar across groups. PFS and OS were significantly improved with LEN-only vs no MT (Table). Rate of hospitalization/100 person-years (PY) was similar across groups ( P= NS, all comparisons) at the end of years 1 and 2. Median duration of hospitalization was numerically longer with no MT. Procedures/surgeries and concomitant medication use were similar across both groups at the end of years 1 and 2. Conclusions: For pts with NDMM, LEN-only vs no MT significantly improved survival outcomes without affecting HRU. Clinical trial information: NCT01081028. [Table: see text]

Impact of t(11;14) on outcomes in African American (AA) and non-AA (NAA) patients (Pts) with newly diagnosed multiple myeloma (NDMM): Connect MM registry

8023

Background: t(11;14) is a common cytogenetic abnormality historically associated with standard-risk and generally favorable MM outcomes, but has shown poor prognosis in some retrospective analyses. Connect MM is a prospective, US, observational, multicenter registry that collects data on management and natural history of NDMM pts in clinical practice. The impact of t(11;14) on survival outcomes was assessed in AA and NAA pts. Methods: Adult NDMM pts who completed induction and were tested for t(11;14) by FISH/cytogenetics were grouped by race (AA vs NAA). Endpoints were PFS and OS. Kaplan-Meier analyses were adjusted for differences in cohort, age, ISS stage, transplant intent, t(4;14), hemoglobin, platelets, calcium, creatinine, and diabetes history. Data cutoff was Jul 7, 2016. Results: 3011 pts were enrolled in 2 cohorts (Cohort 1: n = 1493, Sep 2009–Dec 2011, median follow-up = 39.3 mos; Cohort 2: n = 1518, Dec 2012–Apr 2016, median follow-up = 16.4 mos). Of 1539 (52%) pts tested for t(11;14), 363 (24%) were t(11;14)-positive, including 53 (26%) of 205 AA and 310 (23%) of 1334 NAA pts. First-line bortezomib exposure was similar across groups. A trend of shorter PFS was observed in AA pts with t(11;14) vs AA without t(11;14) (Table). AA pts with t(11;14) had significantly higher risk of death compared to those without t(11;14) and higher rate of early mortality than NAA pts. No differences in PFS or OS were noted in NAA pts with or without t(11;14). For OS, the interaction between race and t(11;14) status was statistically significant ( P= 0.004). Conclusions: In Connect MM, the effect of t(11;14) on OS was significantly different between AA and NAA pts. t(11;14) was associated with poorer survival outcomes in AA pts, and thus, may be a risk factor for poor prognosis. Additional analyses will be conducted to elucidate the role of induction treatment, transplant and maintenance in AA and non-AA pts with t(11;14). Clinical trial information: NCT01081028. [Table: see text]

Impact of post-autologous stem cell transplant (ASCT) maintenance therapy on outcomes in patients (Pts) with newly diagnosed multiple myeloma (NDMM) using the large prospective community-based Connect MM registry

8040

Background: Maintenance therapy (MT) improved progression-free survival (PFS) and overall survival (OS) in MM clinical trials. The observational Connect MM registry, which is largely community based, was used to assess impact of MT on outcomes in ASCT-eligible NDMM pts. Methods: Adult NDMM pts ≤60 days from diagnosis were eligible for enrollment. Pts receiving induction and ASCT were included and analyzed by 4 MT regimens: No MT, lenalidomide-based (LEN), bortezomib-based (BORT), and LEN+BORT MT. Duration was from 100 days post-ASCT (no MT group) or start of MT until progressive disease, death, discontinuation, or data cutoff. End points were PFS, 2nd PFS, OS, and safety. An exploratory analysis of the impact of baseline characteristics was performed. Results: Of 1493 enrolled pts (Cohort 1; Sep 2009 – Dec 2011), 1450 were treated; 81% (n=1173) were in a community setting. A total of 432 (29%) met analysis criteria. Data cutoff was Jan 7, 2016 (median follow-up of 39.3 mo). Median age was 60 y (range, 24-78 y); 60%, men; and 86%, white. 165 pts did not receive MT. Of 267 pts receiving MT, 213 (80%) received LEN; 30 (11%), BORT; and 16 (6%), LEN+BORT. Only LEN MT is presented, as interpretation of other MT data was limited by small sample sizes. Median treatment duration for LEN MT vs No MT was 35.2 vs 26.1 mo, respectively. PFS and OS significantly increased with LEN MT vs No MT (Table); 2nd PFS was similar for both. Exploratory analyses showed generally similar PFS and OS improvements across subgroups (age, ECOG status, ISS stage, risk group, and induction regimen). No new safety signals were observed. Conclusions: In ASCT-eligible NDMM pts, PFS and OS improved with LEN MT vs No MT and appeared to be independent of induction regimen. Preliminary analysis of 2nd PFS suggests no impact on the efficacy of 2nd line therapy. These data from a largely community-based setting confirm results from randomized phase III trials. Clinical trial information: NCT01081028. [Table: see text]

Phase II study of the c-MET inhibitor tivantinib (ARQ 197) in patients with relapsed or relapsed/refractory multiple myeloma

The hepatocyte growth factor/c-MET pathway has been implicated in the pathobiology of multiple myeloma, and c-MET inhibitors induce myeloma cell apoptosis, suggesting that they could be useful clinically. We conducted a phase II study with the c-MET inhibitor tivantinib in patients with relapsed, or relapsed and refractory myeloma whose disease had progressed after one to four prior therapies. Tivantinib, 360 mg orally per dose, was administered twice daily continuously over a 4-week treatment cycle without a cap on the number of allowed cycles, barring undue toxicities or disease progression. Primary objectives were to determine the overall response rate and the toxicities of tivantinib in this patient population. Sixteen patients were enrolled in a two-stage design. Notable grade 3 and 4 hematological adverse events were limited to neutropenia in five and four patients, respectively. Nonhematological adverse events of grade 3 or higher included hypertension (in four patients); syncope, infection, and pain (two each); and fatigue, cough, and pulmonary embolism (one each). Four of 11 evaluable patients (36%) had stable disease as their best response, while the remainder showed disease progression. Overall, tivantinib as a single agent did not show promise for unselected relapsed/refractory myeloma patients. However, the ability to achieve stable disease does suggest that combination regimens incorporating targeted inhibitors in patients with c-MET pathway activation could be of interest.

Outcome of Patients with Multiple Myeloma and CKS1B Gene Amplification after Autologous Hematopoietic Stem Cell Transplantation

The gain/amplification of the CKS1B gene on chromosome 1q21 region is associated with a poor outcome in patients with multiple myeloma (MM). However, there are limited data on the outcome of patients with CKS1B amplification after a single high-dose chemotherapy and autologous hematopoietic stem cell transplantation (auto-HCT). We retrospectively evaluated the outcome of patients with CKS1B amplification who received an auto-HCT between June 2012 and July 2014 at our institution. We identified 58 patients with MM and CKS1B gene amplification detected by fluorescent in situ hybridization (FISH). We compared their outcomes with a propensity score-matched control group of 58 patients without CKS1B amplification who were treated at approximately the same time. The primary objective was to compare the progression-free (PFS) and overall survival (OS) between the CKS1B and the control groups. Stratified log-rank test with the matched pairs as strata and double robust estimation under the Cox model were used to assess the effect of CKS1B gene amplification on PFS or OS in the matched cohort. Patients in the CKS1B and control groups were well matched for age, gender, disease status, year of auto-HCT, response to pretransplantation therapy, and baseline hemoglobin level. In both groups, 57% patients were in first remission and 43% had relapsed disease at auto-HCT. Twenty-seven (47%) patients with CKS1B amplification had concurrent monosomy 13 or 13q deletion; 6 (10%) by conventional cytogenetics only, 16 (28%) by FISH only, and 5 (9%) by both. Median follow-up after auto-HCT was 25.4 months. The median PFS of the CKS1B and the control groups were 15.0 months and 33.0 months (P = .002), respectively. The median OS have not been reached yet. The 2-year OS rates in the CKS1B and the control groups were 62% and 91% (P = .02), respectively. In conclusion, Patients with CKS1B amplification are more likely to have additional high-risk cytogenetic abnormalities and a shorter PFS and OS after an auto-HCT.

Outcomes in patients with multiple myeloma with TP53 deletion after autologous hematopoietic stem cell transplant

TP53 gene deletion is associated with poor outcomes in multiple myeloma (MM). We report the outcomes of patients with MM with and without TP53 deletion who underwent immunomodulatory drug (IMiD) and/or proteasome inhibitor (PI) induction followed by autologous hematopoietic stem cell transplant (auto-HCT). We identified 34 patients with MM and TP53 deletion who underwent IMiD and/or PI induction followed by auto-HCT at our institution during 2008-2014. We compared their outcomes with those of control patients (n = 111) with MM without TP53 deletion. Median age at auto-HCT was 59 years in the TP53-deletion group and 58 years in the control group (P = 0.4). Twenty-one patients (62%) with TP53 deletion and 69 controls (62%) achieved at least partial remission before auto-HCT (P = 0.97). Twenty-three patients (68%) with TP53 deletion and 47 controls (42%) had relapsed disease at auto-HCT (P = 0.01). Median progression-free survival was 8 months for patients with TP53 deletion and 28 months for controls (P < 0.001). Median overall survival was 21 months for patients with TP53 deletion and 56 months for controls (P < 0.001). On multivariate analysis of both groups, TP53 deletion (hazard ratio 3.4, 95% confidence interval 1.9-5.8, P < 0.001) and relapsed disease at auto-HCT (hazard ratio 2.0, 95% confidence interval 1.2-3.4, P = 0.008) were associated with a higher risk of earlier progression. In MM patients treated with PI and/or IMiD drugs, and auto-HCT, TP53 deletion and relapsed disease at the time of auto-HCT are independent predictors of progression. Novel approaches should be evaluated in this high-risk population. Am. J. Hematol. 91:E442-E447, 2016. © 2016 Wiley Periodicals, Inc.

Prolonged survival with a longer duration of maintenance lenalidomide after autologous hematopoietic stem cell transplantation for multiple myeloma

BACKGROUND

Although lenalidomide maintenance therapy has demonstrated improved outcomes after autologous hematopoietic stem cell transplantation (auto-HCT) for patients with multiple myeloma (MM), the impact of the duration of this therapy is not clearly known.

METHODS

This study retrospectively analyzed all MM patients who were placed on maintenance lenalidomide after auto-HCT between January 2007 and December 2013. Progression-free survival (PFS) and overall survival (OS) were analyzed in multivariate Cox proportional hazards regression models that included the duration of maintenance as a time-dependent covariate.

RESULTS

Of the 464 patients identified, 46% initiated therapy early (<4 months after auto-HCT). The median PFS and OS were 38 and 78 months, respectively. Improvements in PFS (hazard ratio [HR], 0.13; 95% confidence interval [CI], 0.04-0.38; P < .001) and OS (HR, 0.09; 95% CI, 0.03-0.26; P < .001) were seen for those on maintenance for >2 years versus those on maintenance for ≤2 years. For those on maintenance for >3 versus those on maintenance for ≤3 years, this trend continued with improvements seen in PFS (HR, 0.02; 95% CI, 0.00-0.44; P = .012) and OS (HR, 0.05; 95% CI, 0.00-0.83; P = .037). The incidence of second primary malignancies (SPMs) in the entire cohort was 3%. No differences were seen in survival between early and late initiators of maintenance lenalidomide.

CONCLUSIONS

A longer duration of maintenance therapy was associated with longer survival. The incidence of SPMs was low, and they were not associated with the duration of maintenance. The timing of the initiation of maintenance had no effect on survival. Cancer 2016;122:3831-3837. © 2016 American Cancer Society.

Thymidine phosphorylase exerts complex effects on bone resorption and formation in myeloma

Myelomatous bone disease is characterized by the development of lytic bone lesions and a concomitant reduction in bone formation, leading to chronic bone pain and fractures. To understand the underlying mechanism, we investigated the contribution of myeloma-expressed thymidine phosphorylase (TP) to bone lesions. In osteoblast progenitors, TP up-regulated the methylation of RUNX2 and osterix, leading to decreased bone formation. In osteoclast progenitors, TP up-regulated the methylation of IRF8 and thereby enhanced expression of NFATc1 (nuclear factor of activated T cells, cytoplasmic 1 protein), leading to increased bone resorption. TP reversibly catalyzes thymidine into thymine and 2-deoxy-d-ribose (2DDR). Myeloma-secreted 2DDR bound to integrin αVβ3/α5β1 in the progenitors, activated PI3K (phosphoinositide 3-kinase)/Akt signaling, and increased DNMT3A (DNA methyltransferase 3A) expression, resulting in hypermethylation of RUNX2, osterix, and IRF8 This study elucidates an important mechanism for myeloma-induced bone lesions, suggesting that targeting TP may be a viable approach to healing resorbed bone in patients. Because TP overexpression is common in bone-metastatic tumors, our findings could have additional mechanistic implications.

Lenalidomide, Thalidomide, and Pomalidomide Reactivate the Epstein-Barr Virus Lytic Cycle through Phosphoinositide 3-Kinase Signaling and Ikaros Expression

PURPOSE

Lenalidomide, thalidomide, and pomalidomide (LTP) are immunomodulatory agents approved for use in multiple myeloma, but in some settings, especially with alkylating agents, an increase in Hodgkin lymphoma and other secondary primary malignancies (SPM) has been noted. Some of these malignancies have been linked to Epstein-Barr virus (EBV), raising the possibility that immunomodulatory drugs disrupt latent EBV infection.

EXPERIMENTAL DESIGN

We studied the ability of LTP to reactivate latently infected EBV-positive cell lines in vitro and in vivo, and evaluated the EBV viral load in archived serum samples from patients who received a lenalidomide, thalidomide, and dexamethasone (LTD) combination.

RESULTS

Treatment of EBV-infected B-cell lines with LTP at physiologically relevant concentrations induced the immediate early gene BZLF1, the early gene BMRF1, and the late proteins VCA and BCFR1. This occurred in the potency order pomalidomide > lenalidomide > thalidomide, and the nucleoside analogue ganciclovir enhanced the cytotoxic effects of lenalidomide and pomalidomide in Burkitt lymphoma cells in vitro and in vivo EBV reactivation was related to PI3K stimulation and Ikaros suppression, and blocked by the PI3Kδ inhibitor idelalisib. Combinations of lenalidomide with dexamethasone or rituximab increased EBV reactivation compared with lenalidomide alone and, importantly, lenalidomide with melphalan produced even greater reactivation.

CONCLUSIONS

We conclude LTP may reactivate EBV-positive resting memory B cells thereby enhancing EBV lytic cycle and host immune suppression. Clin Cancer Res; 22(19); 4901-12. ©2016 AACR.

Tight Junction Protein 1 Modulates Proteasome Capacity and Proteasome Inhibitor Sensitivity in Multiple Myeloma via EGFR/JAK1/STAT3 Signaling

Proteasome inhibitors have revolutionized outcomes in multiple myeloma, but they are used empirically, and primary and secondary resistance are emerging problems. We have identified TJP1 as a determinant of plasma cell proteasome inhibitor susceptibility. TJP1 suppressed expression of the catalytically active immunoproteasome subunits LMP7 and LMP2, decreased proteasome activity, and enhanced proteasome inhibitor sensitivity in vitro and in vivo. This occurred through TJP1-mediated suppression of EGFR/JAK1/STAT3 signaling, which modulated LMP7 and LMP2 levels. In the clinic, high TJP1 expression in patient myeloma cells was associated with a significantly higher likelihood of responding to bortezomib and a longer response duration, supporting the use of TJP1 as a biomarker to identify patients most likely to benefit from proteasome inhibitors.

Siltuximab (CNTO 328) with lenalidomide, bortezomib and dexamethasone in newly-diagnosed, previously untreated multiple myeloma: an open-label phase I trial

The safety and efficacy of siltuximab (CNTO 328) was tested in combination with lenalidomide, bortezomib and dexamethasone (RVD) in patients with newly-diagnosed, previously untreated symptomatic multiple myeloma. Fourteen patients were enrolled in the study, eleven of whom qualified to receive therapy. A majority of patients (81.8%) completed the minimal number or more of the four required cycles, while two patients completed only three cycles. The maximum tolerated dose (MTD) of siltuximab with RVD was dose level −1 (siltuximab: 8.3 mg/kg; bortezomib: 1.3 mg/m²; lenalidomide: 25 mg; dexamethasone: 20 mg). Serious adverse events were grade 3 pneumonia and grade 4 thrombocytopenia, and no deaths occurred during the study or with follow-up (median follow-up 28.1 months). An overall response rate, after 3–4 cycles of therapy, of 90.9% (95% confidence interval (CI): 58.7%, 99.8%) (9.1% complete response (95% CI: 0.2%, 41.3%), 45.5% very good partial response (95% CI: 16.7%, 76.6%) and 36.4% partial response (95% CI: 10.9%, 69.2%)) was seen. Two patients withdrew consent, and nine patients (81.8%) opted for autologous stem cell transplantation.

Phase I Study of the Novel Investigational NEDD8-Activating Enzyme Inhibitor Pevonedistat (MLN4924) in Patients with Relapsed/Refractory Multiple Myeloma or Lymphoma

PURPOSE

Evaluate the safety, pharmacokinetic profile, pharmacodynamic effects, and antitumor activity of the first-in-class investigational NEDD8-activating enzyme (NAE) inhibitor pevonedistat (TAK-924/MLN4924) in patients with relapsed/refractory lymphoma or multiple myeloma.

EXPERIMENTAL DESIGN

Patients with relapsed/refractory myeloma (n = 17) or lymphoma (n = 27) received intravenous pevonedistat 25 to 147 mg/m(2) on days 1, 2, 8, 9 (schedule A; n = 27) or 100 to 261 mg/m(2) on days 1, 4, 8, 11 (schedule B; n = 17) of 21-day cycles.

RESULTS

Maximum tolerated doses were 110 mg/m(2) (schedule A) and 196 mg/m(2) (schedule B). Dose-limiting toxicities included febrile neutropenia, transaminase elevations, muscle cramps (schedule A), and thrombocytopenia (schedule B). Common adverse events included fatigue and nausea. Common grade ≥3 events were anemia (19%; schedule A), and neutropenia and pneumonia (12%; schedule B). Clinically significant myelosuppression was uncommon. There were no treatment-related deaths. Pevonedistat pharmacokinetics exhibited a biphasic disposition phase and approximate dose-proportional increases in systemic exposure. Consistent with the short mean elimination half-life of approximately 8.5 hours, little-to-no drug accumulation in plasma was seen after multiple dosing. Pharmacodynamic evidence of NAE inhibition included increased skin levels of CDT-1 and NRF-2 (substrates of NAE-dependent ubiquitin ligases), and increased NRF-2-regulated gene transcript levels in whole blood. Pevonedistat-NEDD8 adduct was detected in bone marrow aspirates, indicating pevonedistat target engagement in the bone marrow compartment. Three lymphoma patients had partial responses; 30 patients achieved stable disease.

CONCLUSIONS

Pevonedistat demonstrated anticipated pharmacodynamic effects in the clinical setting, a tolerable safety profile, and some preliminary evidence that may be suggestive of the potential for activity in relapsed/refractory lymphoma.

Novel approaches to treatment of double-refractory multiple myeloma

Multiple myeloma (MM) refractory to both proteasome inhibitors and immunomodulatory agents (IMiDs; double-refractory myeloma) has a poor prognosis. With the more frequent use of these agents as part of initial therapy, and then in the maintenance setting until disease progression, such drug resistance is an emerging problem of great significance. New therapeutic strategies are clearly needed for this patient population, including the development of more potent agents within existing antimyeloma drug classes, exploration of rational combinations of both novel and conventional drugs, and validation of new myeloma drug targets. Several approaches have shown substantial promise, including use of the second-generation proteasome inhibitor carfilzomib and the third-generation IMiD pomalidomide, which led to the recent regulatory approval of both agents. In addition, the kinesin-spindle protein KSP inhibitor ARRY-520 has shown activity as a first-in-class drug in myeloma therapeutics, whereas the histone deacetylase (HDAC) inhibitors vorinostat and panobinostat have demonstrated efficacy when used in rational combinations. This overview provides a summary of novel agents that have shown activity in double-refractory myeloma in recent phase II and III clinical trials, and a framework for future studies that will help to improve outcomes in this patient population.