Safety and efficacy of belantamab mafodotin with pembrolizumab in patients with relapsed or refractory multiple myeloma

BACKGROUND

Belantamab mafodotin (belamaf) has shown promising antimyeloma activity in relapsed or refractory multiple myeloma (RRMM) as a single agent. It was hypothesized that its multimodal activity may be enhanced by programmed cell death protein 1 pathway inhibition and activation of T cell-mediated antitumor responses. This study investigated the efficacy and safety of belamaf with pembrolizumab in patients with RRMM.

METHODS

DREAMM-4 (NCT03848845) was an open-label, single-arm, phase 1/2 study divided into dose-escalation (part 1) and dose-expansion (part 2) phases. Patients were ≥18 years old with ≥3 prior lines of therapy including a proteasome inhibitor, an immunomodulatory drug, and an anti-CD38 agent. Patients received belamaf (2.5 or 3.4 mg/kg, part 1; 2.5 mg/kg, part 2) and 200 mg pembrolizumab for ≤35 cycles.

RESULTS

Of 41 enrolled patients, 34 (n = 6 part 1, n = 28 part 2) who received 2.5 mg/kg belamaf plus pembrolizumab were included in this final analysis. Sixteen patients (47%) achieved an overall response. Minimal residual disease negativity was achieved in three of 10 patients who had very good partial response or better. Five of eight patients who had prior anti-B-cell maturation antigen therapy achieved partial response or better, including two who had B-cell maturation antigen-refractory disease. Common grade ≥3 adverse events were keratopathy (38%) and thrombocytopenia (29%). Despite belamaf-related ocular events, quality-of-life measures remained stable over time. No new safety signals were observed.

CONCLUSIONS

The results of DREAMM-4 demonstrated clinical activity and a favorable safety profile of belamaf plus pembrolizumab in patients with RRMM. This trial is registered at www.

CLINICALTRIALS

gov as NCT03848845.

Belantamab mafodotin, pomalidomide and dexamethasone in refractory multiple myeloma: a phase 1/2 trial

Due to evolving treatment standards for newly diagnosed multiple myeloma, many patients will be triple-class exposed after initial relapses and have poor survival. Novel therapies and combinations are therefore required to improve outcomes. B cell maturation antigen (BCMA)-targeted biologics have emerged as an important new area of therapeutics for relapsed multiple myeloma. The two-part ALGONQUIN trial evaluated various doses and schedules of the anti-BCMA antibody-drug conjugate belantamab mafodotin plus pomalidomide and dexamethasone for patients who are lenalidomide refractory and proteosome inhibitor exposed. The primary endpoints, including evaluating dose-limiting toxicities, establishing the recommended Part 2 dose (RP2D) and overall response rate for patients treated at the RP2D, were met. Secondary efficacy endpoints included progression-free survival and overall survival. Patients treated on study (N = 87) had a median of three previous regimens and 55.2% were triple-class refractory. At the RP2D the most common adverse events were decrease in best-corrected visual acuity (71.1%), keratopathy (65.8%), fatigue (57.9%), infection (47.4%; 7.9% grade ≥3), neutropenia (39.5%) and thrombocytopenia (39.5%). For RP2D patients (n = 38), the overall response rate was 85.3%, ≥very good partial response 75.7% and estimated two-year progression-free survival 52.8% (95% confidence interval, 33.9% to 82.4%), at a median follow-up of 13.9 months. The RP2D schedule was associated with manageable antibody-drug conjugate-associated corneal adverse events and improved tolerability without compromising efficacy. Belantamab mafodotin plus pomalidomide and dexamethasone induced durable responses with promising overall survival in relapsed multiple myeloma, the results of which are yet to be confirmed in the phase 3 DREAMM-8 study. ClinicalTrials.gov Identifier: NCT03715478 .

Single-agent belantamab mafodotin in patients with relapsed/refractory multiple myeloma: Final analysis of the DREAMM-2 trial

BACKGROUND

Patients with relapsed/refractory multiple myeloma (RRMM) have a high unmet treatment need. Belantamab mafodotin (belamaf), a first-in-class, B-cell maturation antigen-binding antibody-drug conjugate, eliminates myeloma cells through direct cell killing and an anti-myeloma immune response.

METHODS

DREAMM-2 (NCT03525678) was a phase 2, two-arm, open-label trial in patients with heavily pretreated RRMM who had three or more prior therapies, were refractory to an immunomodulatory agent and a proteasome inhibitor, and refractory or intolerant to an anti-CD38 monoclonal antibody. Belamaf was given at 2.5 or 3.4 mg/kg every 3 weeks. The primary end point was overall response rate (ORR); secondary end points included progression-free survival (PFS), overall survival (OS), safety, ocular symptoms, and health-related quality of life (HRQOL).

RESULTS

This final analysis (cutoff date, March 31, 2022), N = 223, with median follow-up of 12.5 and 13.8 months, demonstrated an ORR of 32% and 35%, median PFS of 2.8 and 3.9 months, and median OS of 15.3 and 14.0 months in the 2.5 mg/kg and 3.4 mg/kg cohorts, respectively. Median duration of response was 12.5 and 6.2 months. No new safety signals were observed; the most common Grade 3 and 4 adverse events were keratopathy (29% vs. 25%), thrombocytopenia (22% vs. 29%), and anemia (21% vs. 28%). HRQOL outcomes suggest that overall global health status/quality of life, physical and role functioning, and overall disease symptoms were maintained or improved during treatment.

CONCLUSIONS

This final analysis of DREAMM-2 confirms that in patients with triple-class refractory RRMM, single-agent belamaf results in durable and clinically meaningful responses with a manageable safety profile.

The Impact of CD34+ Cell Collection Yields for Autologous Transplant on Survival Outcomes in Multiple Myeloma

INTRODUCTION

According to previous data, higher yields of stem-cells collected to support autologous transplantation may predict for improved outcomes. We aimed to assess the association between high stem-cells collection and survival outcomes in multiple myeloma (MM) MATERIALS AND METHODS: We reviewed all patients who underwent autologous transplantation for MM at our center over a 10-year period, and initially used a predefined threshold of 8 × 106/kg used in previous studies.

RESULTS

Six hundred twenty-one patients were analyzed. Higher mobilization did not correlate with favorable outcomes post-transplant. The most efficient mobilizers, collecting ≥8 × 106/kg (n = 478) achieved a shorter median progression-free survival (PFS) of 24.1m versus 34.5m in patients collecting 4.5 to 8 × 106/kg (n = 129). A small group (n = 14) collecting ≤4.5 × 106/kg but minimum of 2 × 106/kg to support autologous transplantation exhibited the worst outcomes (median PFS 11.4m). Further analysis of potential confounders identified greater use of bortezomib induction in the lower mobilizers, however, sensitivity analysis in patients receiving bortezomib revealed similar results- worst outcomes to the most efficient mobilizers.

CONCLUSION

Although bortezomib is not considered stem-cell toxic, it may be associated with lower stem cell collection yields. Bortezomib's efficacy at induction may partially explain the improved outcomes, however, other factors may be involved, and are discussed. We can conclude that with our large cohort and long follow-up, high stem-cell mobilization does not appear to predict for a long-term survival advantage.

Elranatamab in relapsed or refractory multiple myeloma: the MagnetisMM-1 phase 1 trial

Multiple myeloma (MM) is a plasma cell malignancy expressing B cell maturation antigen (BCMA). Elranatamab, a bispecific antibody, engages BCMA on MM and CD3 on T cells. The MagnetisMM-1 trial evaluated its safety, pharmacokinetics and efficacy. Primary endpoints, including the incidence of dose-limiting toxicities as well as objective response rate (ORR) and duration of response (DOR), were met. Secondary efficacy endpoints included progression-free survival (PFS) and overall survival (OS). Eighty-eight patients with relapsed or refractory MM received elranatamab monotherapy, and 55 patients received elranatamab at efficacious doses. Patients had received a median of five prior regimens; 90.9% were triple-class refractory, 29.1% had high cytogenetic risk and 23.6% received prior BCMA-directed therapy. No dose-limiting toxicities were observed during dose escalation. Adverse events included cytopenias and cytokine release syndrome. Exposure was dose proportional. With a median follow-up of 12.0 months, the ORR was 63.6% and 38.2% of patients achieving complete response or better. For responders, the median DOR was 17.1 months. All 13 patients evaluable for minimal residual disease achieved negativity. Even after prior BCMA-directed therapy, 53.8% achieved response. For all 55 patients, median PFS was 11.8 months, and median OS was 21.2 months. Elranatamab achieved durable responses, manageable safety and promising survival for patients with MM. ClinicalTrials.gov Identifier: NCT03269136 .

Mezigdomide plus Dexamethasone in Relapsed and Refractory Multiple Myeloma

BACKGROUND

Despite recent progress, multiple myeloma remains incurable. Mezigdomide is a novel cereblon E3 ubiquitin ligase modulator with potent antiproliferative and tumoricidal activity in preclinical models of multiple myeloma, including those resistant to lenalidomide and pomalidomide.

METHODS

In this phase 1-2 study, we administered oral mezigdomide in combination with dexamethasone to patients with relapsed and refractory myeloma. The primary objectives of phase 1 (dose-escalation cohort) were to assess safety and pharmacokinetics and to identify the dose and schedule for phase 2. In phase 2 (dose-expansion cohort), objectives included the assessment of the overall response (partial response or better), safety, and efficacy of mezigdomide plus dexamethasone at the dose and schedule determined in phase 1.

RESULTS

In phase 1, a total of 77 patients were enrolled in the study. The most common dose-limiting toxic effects were neutropenia and febrile neutropenia. On the basis of the phase 1 findings, investigators determined the recommended phase 2 dose of mezigdomide to be 1.0 mg, given once daily in combination with dexamethasone for 21 days, followed by 7 days off, in each 28-day cycle. In phase 2, a total of 101 patients received the dose identified in phase 1 in the same schedule. All patients in the dose-expansion cohort had triple-class-refractory multiple myeloma, 30 patients (30%) had received previous anti-B-cell maturation antigen (anti-BCMA) therapy, and 40 (40%) had plasmacytomas. The most common adverse events, almost all of which proved to be reversible, included neutropenia (in 77% of the patients) and infection (in 65%; grade 3, 29%; grade 4, 6%). No unexpected toxic effects were encountered. An overall response occurred in 41% of the patients (95% confidence interval [CI], 31 to 51), the median duration of response was 7.6 months (95% CI, 5.4 to 9.5; data not mature), and the median progression-free survival was 4.4 months (95% CI, 3.0 to 5.5), with a median follow-up of 7.5 months (range, 0.5 to 21.9).

CONCLUSIONS

The all-oral combination of mezigdomide plus dexamethasone showed promising efficacy in patients with heavily pretreated multiple myeloma, with treatment-related adverse events consisting mainly of myelotoxic effects. (Funded by Celgene, a Bristol-Myers Squibb Company; CC-92480-MM-001 ClinicalTrials.gov number, NCT03374085; EudraCT number, 2017-001236-19.).

Single-cell profiling of multiple myeloma reveals molecular response to FGFR3 inhibitor despite clinical progression

Genomic characterization of cancer has enabled identification of numerous molecular targets, which has led to significant advances in personalized medicine. However, with few exceptions, precision medicine approaches in the plasma cell malignancy multiple myeloma (MM) have had limited success, likely owing to the subclonal nature of molecular targets in this disease. Targeted therapies against FGFR3 have been under development for the past decade in the hopes of targeting aberrant FGFR3 activity in MM. FGFR3 activation results from the recurrent transforming event of t(4;14) found in ∼15% of MM patients, as well as secondary FGFR3 mutations in this subgroup. To evaluate the effectiveness of targeting FGFR3 in MM, we undertook a phase 2 clinical trial evaluating the small-molecule FGFR1-4 inhibitor, erdafitinib, in relapsed/refractory myeloma patients with or without FGFR3 mutations (NCT02952573). Herein, we report on a single t(4;14) patient enrolled on this study who was identified to have a subclonal FGFR3 stop-loss deletion. Although this individual eventually progressed on study and succumbed to their disease, the intended molecular response was revealed through an extensive molecular characterization of the patient's tumor at baseline and on treatment using single-cell genomics. We identified elimination of the FGFR3-mutant subclone after treatment and expansion of a preexisting clone with loss of Chromosome 17p. Altogether, our study highlights the utility of single-cell genomics in targeted trials as they can reveal molecular mechanisms that underlie sensitivity and resistance. This in turn can guide more personalized and targeted therapeutic approaches, including those that involve FGFR3-targeting therapies.

Myeloma immunoglobulin rearrangement and translocation detection through targeted capture sequencing

Multiple myeloma is a plasma cell neoplasm characterized by clonal immunoglobulin V(D)J signatures and oncogenic immunoglobulin gene translocations. Additional subclonal genomic changes are acquired with myeloma progression and therapeutic selection. PCR-based methods to detect V(D)J rearrangements can have biases introduced by highly multiplexed reactions and primers undermined by somatic hypermutation, and are not readily extended to include mutation detection. Here, we report a hybrid-capture approach (CapIG-seq) targeting the 3' and 5' ends of the V and J segments of all immunoglobulin loci that enable the efficient detection of V(D)J rearrangements. We also included baits for oncogenic translocations and mutation detection. We demonstrate complete concordance with matched whole-genome sequencing and/or PCR clonotyping of 24 cell lines and report the clonal sequences for 41 uncharacterized cell lines. We also demonstrate the application to patient specimens, including 29 bone marrow and 39 cell-free DNA samples. CapIG-seq shows concordance between bone marrow and cfDNA blood samples (both contemporaneous and follow-up) with regard to the somatic variant, V(D)J, and translocation detection. CapIG-seq is a novel, efficient approach to examining genomic alterations in myeloma.

Antibodies and bispecifics for multiple myeloma: effective effector therapy

The therapeutic landscape in multiple myeloma (MM) has changed dramatically over the last 2 decades. With the introduction of novel immunotherapies, patients with MM can expect deeper responses, longer remissions, and improved overall survival. Since its approval by the US Food and Drug Administration in 2015, the monoclonal antibody specific for CD38, daratumumab, has been incorporated into both frontline and relapsed treatment regimens. Its role as a maintenance therapy is currently being explored. Subsequently, a variety of novel antibody therapeutics have evolved from the success of daratumumab, using similar concepts to target the malignant plasma cell clone. Noteworthy naked monoclonal antibodies include isatuximab, another agent directed against CD38, and elotuzumab, an agent directed against SLAM family member 7. Antibody-drug conjugates, complex molecules composed of an antibody tethered to a cytotoxic drug, target malignant cells and deliver a lethal payload. The first to market is belantamab mafodotin, which targets B-cell maturation antigen (BCMA) on malignant plasma cells and delivers a potent microtubule inhibitor, monomethyl auristatin F. Additionally, bispecific T-cell antibodies are in development that engage the immune system directly by simultaneously binding CD3 on T cells and a target epitope-such as BCMA, G-protein coupled receptor family C group 5 member D (GPRC5d), and Fc receptor homologue 5 (FcRH5)-on malignant cells. Currently, teclistamab, an anti-BCMA bispecific, is closest to approval for commercial use. In this review, we explore the evolving landscape of antibodies in the treatment of MM, including their role in frontline and relapse settings.

Safety and clinical activity of belantamab mafodotin with pembrolizumab in patients with relapsed/refractory multiple myeloma (RRMM): DREAMM-4 Study

8018

Background: Belantamab mafodotin (belamaf; BLENREP), a B-cell maturation antigen (BCMA) targeted antibody–drug conjugate approved for adult patients with RRMM, has a multimodal mechanism that eliminates myeloma cells via direct cytotoxicity and a systemic anti-tumor immune response, which may be augmented by an immune checkpoint inhibitor. DREAMM-4 (NCT03848845) assessed safety and clinical activity of belamaf with pembrolizumab (pembro) in RRMM. Methods: This was a Phase I/II, single-arm, open-label study of adults with RRMM after ≥3 lines of therapy (LOT, including anti-CD38 monoclonal antibody, proteasome inhibitor, and immunomodulator). Part 1 established the dose of belamaf 2.5 mg/kg with pembro 200 mg, both IV Q3W up to 35 cycles, for the Part 2 expansion. Primary efficacy endpoint was investigator-assessed overall response rate (ORR, ≥partial response [PR] per IMWG criteria by investigator). Secondary endpoints included duration of response (DoR), progression-free survival (PFS), adverse events (AEs) per NCI-CTCAE v4.03, and pharmacokinetics (PK). Results: This primary analysis of all treated pts (as of Oct 18, 2021) included 34 pts (6 in Part 1 and 28 in Part 2). In both parts, median prior LOT was 5 (range 3–13); 10 pts (29%) had high-risk cytogenetics and 9 (26%) had extramedullary disease. ORR was 47%, with most responses (10/16 pts) ≥ very good PR (VGPR, Table). Median follow-up was 14.7 months (mo); median (95% CI) DoR was 8.0 (2.1–not reached) mo; median PFS was 3.4 (1.4–5.6) mo. Most pts had ≥1 AE (any grade [Gr]: 97%; Gr ≥3: 74%) and treatment-related AE (TRAE, any Gr: 97%; Gr ≥3: 65%). Most common (≥35%) AEs were keratopathy (any Gr: 76%; Gr ≥3: 38%), vision blurred (any Gr: 38%; Gr ≥3: 0%), and thrombocytopenia (any Gr: 35%; Gr ≥3: 29%). AEs led to dose delays (65%) and dose reductions (32%), but not discontinuation. Nine pts had a serious AE (SAE); 4 pts had ≥1 SAE related to study treatment. Two pts had immune-related AEs of Gr 1 (gout and autoimmune hypothyroidism). Preliminary PK and soluble BCMA data were consistent with single-agent belamaf therapy. Conclusions: Belamaf + pembro demonstrated a favorable ORR compared with single-agent belamaf in heavily pre-treated RRMM. No new TRAEs were identified; AE frequency and severity were similar to single-agent belamaf. Correlative biomarker studies are ongoing. Clinical trial information: NCT03848845. [Table: see text]

CAMMA 1: A multicenter phase Ib trial evaluating the safety, pharmacokinetics, and activity of cevostamab-containing regimens in patients with relapsed or refractory multiple myeloma

TPS8069

Background: Treatment of relapsed/refractory (R/R) multiple myeloma (MM) is challenging, especially in later lines where drug resistance reduces therapeutic options and remission duration. Prognosis is poor (estimated survival: < 1 year) for patients with MM who have received > 3 prior lines of therapy and are triple refractory to immunomodulatory drugs (IMiDs), proteasome inhibitors (PIs) and anti-CD38 agents (Gandhi et al. 2019). Thus R/R MM constitutes a significant unmet medical need. Fragment crystallizable receptor-like 5 (FcRH5) is expressed on myeloma cells with near 100% prevalence (Li et al. 2017), constituting a novel therapeutic target. Cevostamab is an IgG1-based T-cell-engaging bispecific antibody engineered to target the most membrane-proximal domain of FcRH5 on myeloma cells and cluster of differentiation 3 (CD3) on T-cells, resulting in T-cell killing of myeloma cells. Clinical data from the first-in-human Phase I study (GO39775) suggest that cevostamab monotherapy is highly active in heavily pretreated patients with R/R MM, with an overall response rate of 56.7% at the 132–198mg dose level (Trudel et al. ASH 2021 Oral presentation). Thus, cevostamab’s activity and safety profile support further development. Due to their stimulatory effects on T-cell activity, combination of cevostamab with anti-myeloma agents (pomalidomide [P] or daratumumab [D]) may be synergistic, offering the potential to further improve efficacy. CAMMA 1 (NCT04910568) is an open-label, multicenter Phase Ib trial evaluating the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics of cevostamab-containing combination regimens (Arm B: cevostamab plus P and dexamethasone [d] [Pd]; Arm C: cevostamab plus Dd) in patients with R/R MM. A modified weekly schedule for cevostamab is also under investigation (Arm A: cevostamab monotherapy). Methods: Patients must be aged ≥18 years, have an ECOG performance status of 0 or 1 and a life expectancy of > 12 weeks. Patients in all arms have R/R MM; Arms B and C include patients with prior IMiD and PI exposure. Patients with prior CAR-T therapy may enroll with a washout period of 12 weeks post-CAR-T infusion. Cevostamab is administered by intravenous infusion q1w (C1–2)/q2w (C3–6)/q4w (C7–13) in Arm A, q2w (C1–6)/q4w (C7+) in Arm B, and q3w (C1–8)/q4w (C9+) in Arm C. Each arm consists of a safety run-in and an expansion cohort. Enrolment for Arm A is ongoing, with patients receiving up to 13 treatment cycles. Arms B and C are planned; patients will receive treatment until disease progression or unacceptable toxicity. The primary objective is to evaluate the safety and tolerability of cevostamab plus Pd, cevostamab plus Dd and cevostamab monotherapy. Secondary objectives include assessment of activity, PK, immunogenicity, and pharmacodynamic biomarkers. Clinical trial information: NCT04910568.

Elranatamab, a BCMA-targeted T-cell redirecting immunotherapy, for patients with relapsed or refractory multiple myeloma: Updated results from MagnetisMM-1

8014

Background: Elranatamab (PF-06863135) is a bispecific molecule that activates and redirects the T-cell mediated immune response against multiple myeloma (MM), a plasma cell dyscrasia characterized by expression of B-cell maturation antigen (BCMA). MagnetisMM-1 (NCT03269136), the ongoing Phase 1 first-in-human study for elranatamab, was designed to characterize safety, pharmacokinetics (PK), pharmacodynamics, and efficacy for patients (pts) with relapsed or refractory MM. Methods: Elranatamab was given subcutaneously (SC) at doses from 80 to 1000µg/kg either weekly or every 2 weeks (Q2W). Treatment-emergent adverse events (TEAEs) were graded by Common Terminology Criteria for Adverse Events (v4.03) and cytokine release syndrome (CRS) by American Society for Transplantation and Cellular Therapy criteria. PK, cytokine and soluble BCMA profiling, and lymphocyte subset analyses were performed. Response was assessed by International Myeloma Working Group (IMWG) criteria. Minimal residual disease (MRD) was assessed by next generation sequencing at a sensitivity of 1×10-5 in accordance with IMWG criteria. Results: A total of 55 pts received single-agent elranatamab SC at a dose ≥215μg/kg as of 1-Nov-2021. Median age was 64 (range 42-80) years, and 27% of pts were Black/African American or Asian. Median number of prior regimens was 6 (range 2-15), 91% were triple-class refractory, 56% had prior stem cell transplantation, 27% had high cytogenetic risk, and 22% received prior BCMA-targeted therapy. The most common TEAEs regardless of causality included CRS, neutropenia, anemia, injection site reaction, and lymphopenia. With pre-medication and a single priming dose (600µg/kg or 44mg), the overall incidence of CRS at the recommended dose (1000µg/kg or 76mg) was 67% and limited to Grade 1 (33%) or Grade 2 (33%), with no events Grade 3 or higher. Exposure was dose dependent and Q2W dosing achieved exposure associated with anti-myeloma efficacy. Cytokine increases occurred with the first dose and were reduced by pre-medication. Soluble BCMA decreased with disease response, elranatamab therapy was associated with increased peripheral T cell proliferation, and median time to response was 36 days (range 7-73). With a median follow-up of 8.1 months (range 0.3-21) and including only IMWG confirmed responses, 31% of pts achieved complete response or better and the overall response rate was 64% (95% CI 50-75%). For responders (n = 35), median duration of response was not yet reached, but the probability of being event-free at 6 months was 91% (95% CI 73-97%). Single-agent elranatamab induces durable clinical and molecular responses, and updated data including MRD assessment will be presented. Conclusions: Elranatamab shows a manageable safety profile and achieves durable clinical and molecular responses for pts with relapsed or refractory MM. Clinical trial information: NCT03269136.

Fixed duration vs. prolonged duration treatment after first line therapy in patients with systemic light chain amyloidosis

BACKGROUND

The main objective of treatment in systemic light chain amyloidosis (AL amyloidosis) is to achieve the best hematological response. Deeper responses are associated with better organ responses and survival. In this study, we analysed the efficacy of prolonged duration treatment after first line in patients with AL amyloidosis.

METHODS

Retrospective analysis that included patients older than 18 years with AL amyloidosis. We excluded patients with more than 30% marrow plasmacytosis or concurrent multiple myeloma. Two cohorts identified accordingly if they received or not prolonged treatment after the first line. Survival analysis regarding progression free survival (PFS) and overall survival (OS) estimated with Kaplan-Meier and comparisons between groups with log-rank.

RESULTS

Thirty-eight patients were included in the analysis with a median age of 55 years. Twenty-one patients received prolonged duration treatment and 17 did not. In the prolonged duration group, after a median duration of 12 months, the median PFS was 58.8 months. In the fixed duration treatment group, PFS was 30.6 months. The difference was significant with p = .0045 favouring prolonged duration treatment. Organ response was sustained for a longer period in the prolonged duration treatment group. For OS, the difference was not significant.

CONCLUSIONS

Prolonged duration treatment in patients with systemic light chain amyloidosis correlated with better PFS and deeper organ responses. Prospective studies are needed to analyse this further.

Kinetics of response to first- and second-line therapies in multiple myeloma: Assessment by both M-spikes and light chains

OBJECTIVES

The prognostic value of kinetics of response to multiple myeloma (MM) therapy is controversial. We aimed to expand the knowledge on this topic by reviewing the kinetics of response to both first- and second-line MM therapy, utilizing a homogeneously treated cohort and analyzing separately both M-spike and light chain (LC) responses for each patient.

METHODS

We reviewed all patients who received first-line cyclophosphamide, bortezomib and dexamethasone induction followed by autologous transplant with melphalan and lenalidomide maintenance in our center between 2007 and 2019.

RESULTS

Analyzing 360 patients, we observed no correlation between response kinetics to first- versus second-line therapy at the individual patient level. Time to best response to first-line therapy was not a predictor of outcome; however, longer time to best response was highly predictive of a favorable outcome in the second-line setting, independent of other factors. Patients with IgA-MM cleared their M-spike faster than IgG-MM, probably reflecting different half-lives of these isotypes rather than disease biology, as the clearance of LC in both subtypes was similar.

CONCLUSIONS

Analyzing both M-spike and LC responses in a homogenously treated cohort, we identified important insights regarding the prognostic value of kinetic patterns. Prospective analysis may shed more light on unsolved questions.

Longitudinal single-cell analysis of a myeloma mouse model identifies subclonal molecular programs associated with progression

Molecular programs that underlie precursor progression in multiple myeloma are incompletely understood. Here, we report a disease spectrum-spanning, single-cell analysis of the Vκ*MYC myeloma mouse model. Using samples obtained from mice with serologically undetectable disease, we identify malignant cells as early as 30 weeks of age and show that these tumours contain subclonal copy number variations that persist throughout progression. We detect intratumoural heterogeneity driven by transcriptional variability during active disease and show that subclonal expression programs are enriched at different times throughout early disease. We then show how one subclonal program related to GCN2 stress response is progressively activated during progression in myeloma patients. Finally, we use chemical and genetic perturbation of GCN2 in vitro to support this pathway as a therapeutic target in myeloma. These findings therefore present a model of precursor progression in Vκ*MYC mice, nominate an adaptive mechanism important for myeloma survival, and highlight the need for single-cell analyses to understand the biological underpinnings of disease progression.

Minimal Residual Disease in Myeloma: Application for Clinical Care and New Drug Registration

The development of novel agents has transformed the treatment paradigm for multiple myeloma, with minimal residual disease (MRD) negativity now achievable across the entire disease spectrum. Bone marrow-based technologies to assess MRD, including approaches using next-generation flow and next-generation sequencing, have provided real-time clinical tools for the sensitive detection and monitoring of MRD in patients with multiple myeloma. Complementary liquid biopsy-based assays are now quickly progressing with some, such as mass spectrometry methods, being very close to clinical use, while others utilizing nucleic acid-based technologies are still developing and will prove important to further our understanding of the biology of MRD. On the regulatory front, multiple retrospective individual patient and clinical trial level meta-analyses have already shown and will continue to assess the potential of MRD as a surrogate for patient outcome. Given all this progress, it is not surprising that a number of clinicians are now considering using MRD to inform real-world clinical care of patients across the spectrum from smoldering myeloma to relapsed refractory multiple myeloma, with each disease setting presenting key challenges and questions that will need to be addressed through clinical trials. The pace of advances in targeted and immune therapies in multiple myeloma is unprecedented, and novel MRD-driven biomarker strategies are essential to accelerate innovative clinical trials leading to regulatory approval of novel treatments and continued improvement in patient outcomes.

A Personalized Mass Spectrometry-Based Assay to Monitor M-Protein in Patients with Multiple Myeloma (EasyM)

PURPOSE

M-protein is a well-established biomarker used for multiple myeloma monitoring. Current improvements in multiple myeloma treatment created the need to monitor minimal residual disease (MRD) with high sensitivity. Measuring residual levels of M-protein in serum by MS was established as a sensitive assay for disease monitoring. In this study we evaluated the performance of EasyM-a noninvasive, sensitive, MS-based assay for M-protein monitoring.

EXPERIMENTAL DESIGN

Twenty-six patients enrolled in MCRN-001 clinical trial of two high-dose alkylating agents as conditioning followed by lenalidomide maintenance were selected for the study. All selected patients achieved complete responses (CR) during treatment, whereas five experienced progressive disease on study. The M-protein of each patient was first sequenced from the diagnostic serum using our de novo protein sequencing platform. The patient-specific M-protein peptides were then measured by targeted MS assay to monitor the response to treatment.

RESULTS

The M-protein doubling over 6 months measured by EasyM could predict the relapse in 4 of 5 relapsed patients 2 to 11 months earlier than conventional testing. In 21 disease-free patients, the M-protein was still detectable by EasyM despite normal FLC and MRD negativity. Importantly, of 72 MRD negative samples with CR status, 62 were positive by EasyM. The best sensitivity achieved by EasyM, detecting 0.58 mg/L of M-protein, was 1,000- and 200-fold higher compared with serum protein electrophoresis and immunofixation electrophoresis, respectively.

CONCLUSIONS

EasyM was demonstrated to be a noninvasive, sensitive assay with superior performance compared with other assays, making it ideal for multiple myeloma monitoring and relapse prediction.

Longer term outcomes with single-agent belantamab mafodotin in patients with relapsed or refractory multiple myeloma: 13-month follow-up from the pivotal DREAMM-2 study

Background

On the basis of the DREAMM‐2 study (ClinicalTrials.gov identifier NCT03525678), single‐agent belantamab mafodotin (belamaf) was approved for patients with relapsed or refractory multiple myeloma (RRMM) who received ≥4 prior therapies, including anti‐CD38 therapy. The authors investigated longer term efficacy and safety outcomes in DREAMM‐2 after 13 months of follow‐up among patients who received belamaf 2.5 mg/kg.

Methods

DREAMM‐2 is an ongoing, phase 2, open‐label, 2‐arm study investigating belamaf (2.5 or 3.4 mg/kg) in patients with RRMM who had disease progression after ≥3 lines of therapy and were refractory to immunomodulatory drugs and proteasome inhibitors and refractory and/or intolerant to an anti‐CD38 therapy. The primary outcome was the proportion of patients that achieved an overall response, assessed by an independent review committee.

Results

As of January 31, 2020, 10% of patients still received belamaf 2.5 mg/kg. Thirty‐one of 97 patients (32%; 97.5% confidence interval [CI], 21.7%‐43.6%) achieved an overall response, and 18 responders achieved a very good partial response or better. Median estimated duration of response, overall survival, and progression‐free survival were 11.0 months (95% CI, 4.2 months to not reached), 13.7 months (95% CI, 9.9 months to not reached), and 2.8 months (95% CI, 1.6‐3.6 months), respectively. Response and survival outcomes in patients who had high‐risk cytogenetics or renal impairment were consistent with outcomes in the overall population. Outcomes were poorer in patients with extramedullary disease. In patients who had a clinical response and prolonged dose delays (>63 days; mainly because of corneal events), 88% maintained or deepened responses during their first prolonged dose delay. Overall, there were no new safety signals during this follow‐up.

Conclusions

Extended follow‐up confirms sustained clinical activity without new safety signals with belamaf in this heavily pretreated patient population with RRMM.

Extended follow‐up of patients enrolled in the ongoing phase 2 DREAMM‐2 study confirms sustained clinical activity without new safety signals in patients with relapsed or refractory multiple myeloma who receive belantamab mafodotin 2.5 mg/kg every 3 weeks. These data show that belantamab mafodotin has the potential to shift the treatment paradigm in this heavily pretreated, anti‐CD38 monoclonal antibody–exposed patient population, which has a poor prognosis and few alternative treatment options.

Efficacy and safety of elranatamab (PF-06863135), a B-cell maturation antigen (BCMA)-CD3 bispecific antibody, in patients with relapsed or refractory multiple myeloma (MM)

8006

Background: Elranatamab (PF-06863135) is a humanized bispecific monoclonal antibody (IgG2a) that targets BCMA, a member of the tumor necrosis factor receptor superfamily expressed in MM, and CD3 on T cells. We reported results for intravenous (IV) dosing (Raje et al. Blood. 2019;134(S1):1869) and now update for subcutaneous (SC) dosing from the ongoing Phase 1 study (MagnetisMM-1). Methods: Patients (pts) received elranatamab at 80, 130, 215, 360, 600, and 1000μg/kg SC weekly. A modified toxicity probability interval method was used for escalation, with monitoring for dose-limiting toxicity (DLT) to end of the first cycle. Treatment-emergent adverse events (TEAEs) were graded by Common Terminology Criteria for Adverse Events (v4.03), and cytokine release syndrome (CRS) by American Society for Transplantation and Cellular Therapy criteria (Lee et al. Biol Blood Marrow Transplant. 2019;25:625). Response was assessed by International Myeloma Working Group criteria. Pharmacokinetics, cytokine profiling, and T cell immunophenotyping were performed. Results: 30 pts had received elranatamab as of 4-Aug-2020 at 80 (n = 6), 130 (n = 4), 215 (n = 4), 360 (n = 4), 600 (n = 6), or 1000 (n = 6) μg/kg SC weekly. Pts had a median of 8 prior treatments; 87% had triple refractory disease, 97% had prior anti-CD38 therapy, and 23% had prior BCMA-directed antibody drug conjugate or chimeric antigen receptor T cell therapy. The most common all causality TEAEs included lymphopenia (n = 24, 80%; 20% G3, 60% G4), CRS (n = 22, 73%; none > G2), anemia (n = 17, 57%; 43% G3, 3% G4), injection site reaction (n = 16, 53%; none > G2), thrombocytopenia (n = 16, 53%; 23% G3, 17% G4), and neutropenia (n = 12, 40%; 17% G3, 17% G4). Both CRS and immune effector cell-associated neurotoxicity syndrome (n = 6, 20%) were limited to ≤G2 with median durations of 2 and 1.5 days, respectively. No DLT was observed. Exposure increased with dose, and Tmax ranged from 3–7 days. Cytokine increases occurred with the first dose, and increased T-cell proliferation was observed in peripheral blood. The overall response rate (ORR) for doses ≥215μg/kg was 75% (n = 15/20) including partial response (PR; n = 6), very good PR (VGPR; n = 3), complete response (CR; n = 1), and stringent CR (sCR; n = 5). Median time to response was 22 days, and 3 of 4 pts (75%) with prior BCMA-directed therapy achieved response (VGPR, n = 2 and sCR, n = 1). Updated data, including duration of response, will be presented. Conclusions: Elranatamab demonstrated a manageable safety profile, and SC doses ≥215μg/kg achieved ORR of 75% with CR/sCR rate of 30%. These results demonstrate the safety and efficacy of SC elranatamab in this relapsed/refractory population and support ongoing development of elranatamab for pts with MM, both as monotherapy and in combination with standard or novel therapies. Clinical trial information: NCT03269136.

Relationship between corneal exam findings, best-corrected visual acuity (BCVA), and ocular symptoms in patients with relapsed or refractory multiple myeloma (RRMM) receiving belantamab mafodotin (belamaf)

8033

Background: Belantamab mafodotin (GSK2857916; belamaf; BLENREP) is a B-cell maturation antigen (BCMA)-targeting antibody–drug conjugate approved in the US and EU as a monotherapy for the treatment of adult patients with RRMM. Ocular events (OEs) during the pivotal DREAMM-2 trial (NCT03525678) included corneal exam findings (punctate keratopathy and microcyst-like epithelial changes), BCVA changes, and ocular symptoms. Dose reductions or delays based on corneal exam findings and BCVA were used to manage OEs. Here we performed a post hoc investigation of relationships between corneal exam findings, BCVA changes, and patient-reported ocular symptoms to explore if BCVA changes and symptoms could guide dosing, rather than corneal exams. Methods: Eye evaluations (including a corneal exam and BCVA assessment of Snellen visual acuity) were performed on all patients receiving single-agent belamaf (2.5 mg/kg) by ophthalmologists at baseline and prior to each belamaf dose. Changes in the corneal epithelium (Ker) and BCVA were both assessed as per protocol-defined criteria and assessment of grade (Gr) was based on the worse eye. BCVA grading was relative to baseline. Patient-reported ocular symptoms were reported as per the Common Terminology Criteria for Adverse Events. Results: In 12.5% of eye evaluations Gr 3–4 Ker was associated with minimal or no (Gr ≤1) BCVA changes. When patient-reported ocular symptoms were also considered, only 7.5% of evaluations found Gr 3–4 Ker with Gr ≤1 BCVA changes or ocular symptoms. Mild or no (Gr ≤2) Ker was associated with Gr ≤1 BCVA changes in 59.5% of evaluations, or in 38.8% of evaluations with no ocular symptoms reported. Overall, Gr 3–4 Ker were found in 24.9% of evaluations; by contrast, patients had Gr 2–4 BCVA changes or ocular symptoms in 53.7% of evaluations. Association of corneal epithelium changes (Ker) with BCVA changes and ocular symptoms. Conclusions: These findings highlight that BCVA changes and ocular symptoms should be further investigated to determine if they can be used as alternatives (eg, frequency of eye examinations based on symptoms) for the management of belamaf dosing to potentially reduce the burden on patients and healthcare professionals. Clinical trial information: NCT03525678. [Table: see text]

Belantamab mafodotin in combination with novel agents in relapsed/refractory multiple myeloma: DREAMM-5 study design

Belantamab mafodotin (belamaf) is a BCMA-targeted antibody-drug conjugate recently approved as monotherapy for adults with relapsed/refractory multiple myeloma who have received ≥4 prior therapies. Belamaf binds to BCMA and eliminates myeloma cells by multimodal mechanisms of action. The cytotoxic and potential immunomodulatory properties of belamaf have led to novel combination studies with other anticancer therapies. Here, we describe the rationale and design of DREAMM-5, an ongoing Phase I/II platform study evaluating the safety and efficacy of belamaf combined with novel agents, including GSK3174998 (OX40 agonist), feladilimab (an ICOS; GSK3359609), nirogacestat (a gamma-secretase inhibitor; PF-03084014) and dostarlimab (a PD-1 blocker) versus belamaf monotherapy for patients with relapsed/refractory multiple myeloma. Clinical trial registration: NCT04126200 (ClinicalTrials.gov).

A phase-1 trial of linsitinib (OSI-906) in combination with bortezomib and dexamethasone for the treatment of relapsed/refractory multiple myeloma

We report results of a phase-1 study evaluating the safety and anti-cancer activity of the small molecule insulin-like growth factor-1 receptor (IGF-1R) inhibitor, linsitinib combined with bortezomib, and dexamethasone in relapsed/refractory multiple myeloma. Nineteen patients were enrolled across four dose-escalation cohorts (75-150 mg bid). The maximum tolerated dose of linsitinib was 125 mg. The most frequent Grade 3/4 AEs occurring in ≥10% of patients were thrombocytopenia (53%), bone pain (26%), neutropenia (21%), diarrhea (14%), anemia (14%), rash (10%), and lung infection (10%). Study discontinuation due to treatment-related AEs was low (16%). Across all cohorts the ORR was 61% (95% CI: 28.9-75.6%). Three partial response or greater and one stable disease were observed in proteasome inhibitor (PI) refractory patients (n = 5). Median PFS was 7.1 months (95% CI: 3.6-NA). Linsitinib plus bortezomib and dexamethasone demonstrate a manageable safety profile while the clinical benefit particularly in PI refractory patients warrants further exploration.

Belantamab mafodotin in the treatment of relapsed or refractory multiple myeloma

Multiple myeloma remains an incurable disease, with a large proportion of patients in the relapsed/refractory setting often unable to achieve durable responses. Novel, well-tolerated and highly effective therapies in this patient population represent an unmet need. Preclinical studies have shown that B-cell maturation antigen is nearly exclusively expressed on normal and malignant plasma cells, thereby identifying it as a highly selective target for immunotherapeutic approaches. Belantamab mafodotin (GSK2857916, belamaf) is a first-in-class antibody-drug conjugate directed at B-cell maturation antigen and has shown promising activity in clinical trials. In this review, we provide an overview of belantamab mafodotin as a compound and present the available clinical efficacy and safety data in the treatment of relapsed/refractory multiple myeloma.

MM-250: Impact of Prolonged Dose Delays on Response with Belantamab Mafodotin (Belamaf; GSK2857916) Treatment in the DREAMM-2 Study: 13-Month Follow-Up

Context:

Single-agent belamaf demonstrated deep and durable responses in the DREAMM-2 (NCT03525678) primary analysis (1) and long-term follow-up (2,3). Keratopathy (microcyst-like epithelial changes [MECs] observed on eye examination with/without symptoms) were managed through dose delays and reductions.

Objective:

To provide an update on the impact of dose delays on responses in patients receiving single-agent belamaf 2.5-mg/kg in DREAMM-2 (13-month follow-up).

Methods:

In the DREAMM-2 study (single-agent belamaf 2.5 mg/kg [n=97] or 3.4 mg/kg [n=99] Q3W), dose modifications were permitted to manage adverse events (AEs), including keratopathy (MECs), an eye examination finding that may/may not be associated with symptoms. Objective response (IMWG criteria 2016) was assessed by an independent review committee Q3W, regardless of treatment delays. Here, we report a post-hoc analysis on the impact of dose delays >63 days on clinical response in the 2.5-mg/kg arm (the selected dose for future clinical development based on risk–benefit assessment).

Results:

In patients receiving single-agent belamaf (2.5 mg/kg), dose delays (54%) and reductions (35%) due to AEs were common (2,3). Keratopathy (MECs) was the most frequent reason for dose delays (47%) and reductions (25%), leading to only 1 patient (1%) discontinuing treatment (2,3). Of 31 patients with ≥partial response, 16 had prolonged treatment interruptions (>63 days). Of these 16 patients, 14 (88%) continued experiencing a clinical benefit during the first prolonged delay: 6 (38%) deepened their response during delay (1 SD to MR; 2 PR to VGPR; 2 MR to VGPR; 1 VGPR to CR); 6 (38%) maintained the same response category as that of the last evaluable assessment during delay/first evaluable assessment after delay; 2 (13%) had increasing paraproteins during the delay but did not meet progression criteria. Two (13%) developed disease progression (1 patient 6 weeks into delay; 1 patient 3 weeks after delay).

Conclusions:

Despite dose delays lasting for several cycles to manage AEs, most responses were sustained throughout the delay, thus maintaining clinical benefit for the majority of patients.

Funding:

GlaxoSmithKline (205678). Drug linker technology licensed from Seattle Genetics; monoclonal antibody produced using POTELLIGENT Technology licensed from BioWa.

References:

[1] Lonial Lancet Oncol 2020. [2] Lonial ASCO 2020, EP436. [3] Lonial EHA 2020, EP970.

An open-label, pharmacokinetic study of lenalidomide and dexamethasone therapy in previously untreated multiple myeloma (MM) patients with various degrees of renal impairment - validation of official dosing guidelines

Lenalidomide is a backbone agent in the treatment of multiple myeloma, but dose adjustment is required for those with renal impairment (RI). We evaluated the pharmacokinetics (PK) and safety of lenalidomide and dexamethasone as frontline pre-transplant induction, with doses adjusted at start of each cycle based on creatinine clearance, as per the official dosing guidelines. After 4 cycles, PK studies showed that patients with moderate RI (30 ≤ CrCl < 60 mL/min) receiving 10 mg dosing may be under-dosed and those with severe RI (CrCl <30ml/min) appeared appropriately dosed initially, but sustained significant decreases in maximum serum concentration (Cmax) after repeated dosing, due to rapid clinical improvement and enhanced drug clearance. PK drug monitoring during cycle 1 may facilitate appropriate and timely dose adjustments. Adverse events rates did not vary based on severity of RI. No patient discontinued lenalidomide for toxicity. This supports the feasibility and safety of frontline lenalidomide in transplant-eligible patients with RI.

Abstract IA11: Clinical applications of liquid biopsy in multiple myeloma

Multiple myeloma (MM) is characterized by recurrent cytogenetic and molecular abnormalities that have the potential to profoundly impact therapeutic decisions. Conventional karyotyping and/or FISH cytogenetics studies have identified translocations and copy number abnormalities (CNAs) that predict clinical outcomes. More recently, MM whole-exome sequencing studies have uncovered recurrent mutations in genes associated with prognosis and others that are potentially actionable and/or implicated in drug resistance. These observations highlight the need for advanced genomic platforms to inform prognosis and therapeutic decisions.

Currently, molecular profiling of MM is performed on bone marrow (BM) aspirates; however, the genetic information obtained from aspirates is confounded by spatial and temporal intratumor genetic heterogeneity. Genomic studies of MM have confirmed the bias introduced by single-site biopsies, demonstrating that not all mutations are shared between targeted biopsies of extramedullary sites and BM. Further, longitudinal whole-genome sequencing studies have not only uncovered tumor heterogeneity at diagnosis but also subclonal competition with a shifting dominance of tumor clones and accumulation of genetic events during progression that are particularly affected by therapeutic pressures. Thus, information acquired from a single biopsy provides a spatially and temporally limited snapshot of a tumor that likely underestimates the complexity of the tumor genomic landscape.

Analysis of circulating tumor DNA (ctDNA) and in blood plasma has the potential to overcome these barriers, providing access to the genetic landscape of all cancerous lesions and allowing for noninvasive tracking of genomic evolution over time. Circulating biomarkers can provide a “liquid biopsy” alternative to tissue biopsy, providing new opportunities for treatment tailoring based on real-time monitoring from a simple blood test. Here I will discuss the current liquid biopsy technologies under evaluation for genomic characterization of multiple myeloma. I will also describe the potential clinical applications for liquid biopsies to identify patients for targeted therapies, to track genomic changes, and to follow disease burden in patients with multiple myeloma.

Citation Format: Suzanne Trudel, Trevor Pugh. Clinical applications of liquid biopsy in multiple myeloma [abstract]. In: Proceedings of the AACR Special Conference on Advances in Liquid Biopsies; Jan 13-16, 2020; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(11_Suppl):Abstract nr IA11.

Pharmacodynamic (PD) responses drive dose/schedule selection of CC-92480, a novel CELMoD agent, in a phase 1 dose-escalation study in relapsed/refractory multiple myeloma (RRMM)

8531

Background: CC-92480 is a novel cereblon (CRBN) E3 ligase modulator (CELMoD) agent under investigation in a first-in-human phase 1 study (NCT03374085) in RRMM patients (pts). In preclinical studies, CC-92480 demonstrated efficient and sustained degradation of Ikaros/Aiolos leading to broad antiproliferative effects and induction of apoptosis in MM cell lines, and enhanced immune stimulatory effects. Methods: Eligible RRMM pts received escalating doses of CC-92480 + dexamethasone. Several dosing schedules were evaluated in parallel; more continuous with 4-day or 7-day breaks and intensive with longer breaks in a 28-day cycle. Peripheral blood and bone marrow aspirates (BMA) were taken before and during treatment at multiple time points. Levels of Ikaros/Aiolos in T cells, and effects on immunomodulation were assessed by flow cytometry. Weekly levels of free light chain (sFLC) and B-cell maturation antigen (sBCMA) were determined in serum during the first 2 cycles of treatment. BMA clots were analyzed by immunohistochemistry for CRBN, Ikaros, Aiolos, ZFP91, c-Myc, and IRF-4. Results: The rate and depth of Ikaros/Aiolos degradation in T cells increased with dose and reached maximal at ≥0.6 mg QD with sustained degradation over 24 hrs. Substrate recovery occurred during drug holidays with faster recovery at lower doses, and reached full recovery with ≥7-day break for all dose levels tested. B cells decreased with increasing dose, and T-cell proliferation was demonstrated at all doses/schedules. Substrate degradation was also evident in bone marrow plasma cells including in the setting of low CRBN levels. In these heavily pretreated, including triple-class-refractory, RRMM pts, CC-92480 dosing periods led to rapid and sustained decreases in sFLC and sBCMA. This was dose and schedule dependent and correlated with plasma exposure; the longer breaks in the intensive schedules led to rapid rebound of these markers, while the more continuous schedules maintained the depth of suppression. Conclusions: PD responses correlated with dose and schedule. PD samplings at multiple time points during treatment allowed dynamic changes and kinetics of each biomarker in all schedules to be followed and to inform next steps. Ikaros/Aiolos degradation and recovery, coupled with changes in sFLC and sBCMA, guided the adjustment of the dosing schedule during dose escalation in order to optimize efficacy and tolerability. The study is ongoing and selection of the recommended phase 2 dose is pending.

DREAMM-2: Single-agent belantamab mafodotin (GSK2857916) in patients with relapsed/refractory multiple myeloma (RRMM) and high-risk (HR) cytogenetics

8541

Background: Patients with RRMM and HR cytogenetics have a poor prognosis and need effective therapies. In DREAMM-2 (NCT03525678), single-agent belantamab mafodotin (an immunoconjugate targeting B-cell maturation antigen) demonstrated clinically meaningful activity and a manageable safety profile in patients with heavily pretreated RRMM ( Lancet Oncol.2020). We present outcomes in patients with HR-cytogenetics (9-month follow-up). Methods: Patients with RRMM received single-agent belantamab mafodotin (2.5 or 3.4 mg/kg). For this post hoc analysis, HR-cytogenetics included t(4;14), t(14;16), 17p13del, or 1q21+ (tested locally). Results: The median number of cycles was 3 (2.5: range: 1–15) and 4 (3.4: range: 1–14). Overall response rate (ORR; ≥partial response [PR] per independent review committee) was 27% in the 2.5 mg/kg group (22% with ≥very good partial response [VGPR]) and 40% in the 3.4 mg/kg group (27% with ≥VGPR). The median duration of response (DoR) was not reached in the 2.5 mg/kg group and was 6.2 months in the 3.4 mg/kg group. The most common adverse events ( > 30% in either group) were consistent with the overall population ( Lancet Oncol.2020): keratopathy (2.5: 59%;3.4: 79%), thrombocytopenia (2.5: 44%; 3.4: 65%), nausea (2.5: 27%; 3.4: 33%), anemia (2.5: 24%; 3.4: 42%), and blurred vision (2.5: 20%; 3.4: 42%). Conclusions: Patients with HR-cytogenetics maintain deep and durable clinical responses with single-agent belantamab mafodotin, comparable to that reported in the overall population. The safety profile remained consistent with previous reports. Funding: GlaxoSmithKline (205678). Drug linker technology licensed from Seattle Genetics; monoclonal antibody produced using POTELLIGENT Technology licensed from BioWa. Clinical trial information: NCT03525678 . [Table: see text]

DREAMM-2: Single-agent belantamab mafodotin (GSK2857916) in patients with relapsed/refractory multiple myeloma (RRMM) and renal impairment

8519

Background: Renal impairment, a frequent complication and poor prognostic factor in RRMM, often leads to poor tolerability of standard regimens. We report outcomes in patients with renal impairment receiving single-agent belantamab mafodotin (2.5 or 3.4 mg/kg; B-cell maturation antigen targeting immunoconjugate not renally metabolized) from the DREAMM-2 post-hoc analysis (NCT03525678). Methods: Eligible patients with RRMM had no active renal conditions and adequate renal function (based on albumin/creatinine ratio [<500 mg/g] and eGFR [mL/min/1.73 m2]: normal [≥90], mild impairment [mild, ≥60≤90], moderate impairment [mod, ≥30≤60]). Results: Overall response rates (95% CI) in patients with mild/mod impairment (2.5 mg/kg: 32% [21.4–44.0]; 3.4 mg/kg: 36% [25.6–48.5]) were similar to those in the overall population ( Lancet Oncol.2020). The median duration of response (DoR) was not reached (NR) in 2.5 mg/kg mild/mod subgroup (95% CI estimate: 4.2 months–NR); median DoR was 7.5 months (4.9–NR) in 3.4 mg/kg mild/mod subgroup. Rates of keratopathy and albuminuria were similar regardless of renal function; rates of anemia, pyrexia, and thrombocytopenia were more frequent in patients with impaired renal function (Table). eGFR did not change or changed to normal in most patients. Conclusions: Following treatment with single-agent belantamab mafodotin, patients with mild/mod renal impairment achieved a similar efficacy and safety profile as patients with normal renal function. Funding: GlaxoSmithKline (205678). Drug linker technology licensed from Seattle Genetics; monoclonal antibody produced using POTELLIGENT Technology licensed from BioWa. Clinical trial information: NCT03525678 . [Table: see text]

First-in-human phase I study of the novel CELMoD agent CC-92480 combined with dexamethasone (DEX) in patients (pts) with relapsed/refractory multiple myeloma (RRMM)

8500

Background: CC-92480 is a novel cereblon E3 ligase modulator (CELMoD) agent designed for rapid, maximal degradation of Ikaros and Aiolos. In vitro, it has enhanced antiproliferative and tumoricidal activity in MM cell lines, including those resistant to lenalidomide (LEN) and pomalidomide (POM), with strong immune stimulatory activity. Methods: A phase 1, multicenter, dose-escalation study evaluated the maximum tolerated dose (MTD), recommended phase 2 dose, safety, tolerability, and pharmacokinetics of CC-92480 + DEX in heavily pretreated RRMM pts. Eligible pts had progression on or within 60 days of their last MM therapy and were either resistant or intolerant to, or not otherwise candidates for currently available therapies. Several treatment schedules tested escalating doses of CC-92480 + DEX (40 mg; 20 mg if ≥75 yrs). Results: As of Dec 24, 2019, 66 pts had received CC-92480 + DEX. Median age was 67 yrs (range 40–78), median number of prior regimens was 6 (range 2–13). Prior therapies included stem cell transplantation (67%), bortezomib (92%), LEN (89%), POM (83%), and anti-CD38 antibodies (78%). CC-92480 doses explored included 0.1–1.0 mg QD (10/14 days × 2), 0.8–1.0 mg QD (21/28 days), 0.2–0.8 mg BID (3/14 days × 2), and 1.6–2.0 mg QD (7/14 days × 2). MTD was 1.0 mg for both 10/14 × 2 and 21/28 schedules. Grade 3–4 treatment-emergent adverse events (TEAEs) were reported in 58 (88%) pts. Most frequent grade 3–4 TEAEs included neutropenia (53%), infections (30%), anemia (29%), and thrombocytopenia (17%), with 9% grade 3 fatigue. Among different cohorts,10 pts had dose-limiting toxicities (the majority related to neutropenia). Overall response rate (ORR) was 21% (9 very good partial responses [VGPRs]; 5 PRs) for efficacy evaluable population (n = 66). Efficacy was dose and schedule dependent; across two 1.0 mg QD schedules (10/14 × 2 and 21/28), 10 of 21 (48%) pts responded (7 VGPR and 3 PR), with response independent of immunomodulatory drug (IMiD) refractoriness. Plasma exposure increase and peripheral blood Ikaros and Aiolos degradation were dose dependent. Ikaros and Aiolos significantly decreased in bone marrow plasma cells of LEN- and POM-refractory pts. Conclusions: TEAEs of CC-92480 were mainly related to myelosuppression in heavily pretreated, including triple-class-refractory, RRMM pts. Promising activity with 48% ORR at therapeutic doses was observed. The study is ongoing to further optimize dose and schedule, with combination studies underway and dose expansion cohorts planned. Clinical trial information: NCT03374085 .

Pivotal DREAMM-2 study: Single-agent belantamab mafodotin (GSK2857916) in patients with relapsed/refractory multiple myeloma (RRMM) refractory to proteasome inhibitors (PIs), immunomodulatory agents, and refractory and/or intolerant to anti-CD38 monoclonal antibodies (mAbs)

8536

Background: Single-agent belantamab mafodotin (B-cell maturation antigen targeting immunoconjugate) showed clinically meaningful activity and manageable safety in patients with heavily pre-treated RRMM (DREAMM-2, NCT03525678, Lancet Oncol.2020). We report updated results (median follow-up 9 months). Methods: DREAMM-2 is an ongoing single-agent belantamab mafodotin (2.5 or 3.4 mg/kg) study in patients with RRMM after ≥3 prior therapy lines and refractory to an immunomodulatory agent, a PI, and refractory and/or intolerant to an anti-CD38 mAb. Primary endpoint: overall response rate (ORR; ≥partial response per independent review committee). Results: ORR was 31% in the 2.5 mg/kg (19% with ≥very good partial responses [VGPR]) and 35% (24% with ≥VGPR) in the 3.4 mg/kg groups (Table). Duration of response (DoR) was not reached (NR) in the 2.5 mg/kg and 6.2 months in the 3.4 mg/kg groups; 1-year overall survival (OS) estimate was 53%. Common Grade 3/4 AEs ( > 10% in either group) were keratopathy (2.5: 29%; 3.5: 24%), thrombocytopenia (2.5: 21%; 3.4: 32%), anemia (2.5: 20%; 3.4: 27%), pneumonia (2.5: 6%; 3.4: 13%), and neutropenia (2.5: 11%; 3.4: 16%). AEs were managed with dose delays (2.5: 54%; 3.4: 62%) and reductions (2.5: 34%; 3.4: 43%); discontinuations due to AEs were uncommon (2.5: 9%; 3.4: 12%). Conclusions: Single-agent belantamab mafodotin was well-tolerated, and clinically meaningful responses were sustained despite dose modifications with longer follow-up. Funding: GlaxoSmithKline (205678). Drug linker technology licensed from Seattle Genetics; monoclonal antibody produced using POTELLIGENT Technology licensed from BioWa. Clinical trial information: NCT03525678 . [Table: see text]

GO39775: A multicenter phase I trial evaluating the safety, pharmacokinetics, and activity of BFCR4350A, a FcRH5/CD3 T-cell dependent bispecific antibody, in patients with relapsed or refractory multiple myeloma

TPS8551

Background: Multiple myeloma (MM) remains an incurable disease, with estimated median survival of 8–9 months in patients with relapsed or refractory (R/R) disease (Kumar et al. 2014; Usmani et al. 2016). There is no uniform standard of care for R/R MM, and combinations used in later lines have diminishing responses, especially after re-exposure to previously received classes of therapy (Gandhi et al. 2019). New targets and treatment modalities are needed. Fragment crystallizable receptor-like 5 (FcRH5) is expressed on myeloma cells across lines of therapy, and is overexpressed by myeloma cells with 1q21 gain; expression in healthy tissue is restricted to the B-cell lineage, and is retained in plasma cells (Li et al. 2017). BFCR4350A is an IgG-based T-cell-dependent bispecific antibody that was specifically engineered to target the most membrane-proximal domain of FcRH5 on myeloma cells and cluster of differentiation 3 (CD3) on T cells, with dual binding resulting in efficient immune synapse formation and T-cell killing of myeloma cells. BFCR4350A demonstrates potent killing of plasma cells and patient-derived myeloma cells (including those with low levels of FcRH5 expression) in vitro, and complete depletion of bone marrow plasma cells in primates, without severe or prolonged cytokine release (Li et al. 2017). GO39775 (NCT03275103) is an open-label, multicenter Phase I dose-escalation and dose-expansion trial evaluating the safety, pharmacokinetics (PK), and activity of BFCR4350A monotherapy in patients with R/R MM. Methods: Patients must be aged ≥18 years and must have R/R MM for which no established therapies are available or appropriate, or be intolerant to those therapies. Patients with prior CAR-T therapy and/or prior BCMA-directed therapy are not excluded. BFCR4350A is administered by intravenous infusion, and q3w dosing with Cycle 1 single-step or multi-step dosing is being investigated in dose-escalation (Arms A and B, respectively). Enrolment into both arms is ongoing, with patients receiving up to 17 cycles of treatment until disease progression or unacceptable toxicity. Primary objectives are to evaluate safety (including the maximum tolerated dose and dose-limiting toxicities) and to identify a recommended Phase II dose. Secondary objectives include assessment of PK, activity, immunogenicity, and pharmacodynamic biomarkers. Clinical trial information: NCT03275103 .

Toxicity and survival outcomes of autologous stem cell transplant in multiple myeloma patients with renal insufficiency: an institutional comparison between two eras

Autologous stem cell transplant (ASCT) is a feasible treatment option for multiple myeloma (MM) patients with renal insufficiency; however, these patients tend to experience higher rates of drug toxicity and transplant-related mortality (TRM) during ASCT. Recent adoption of bortezomib-based induction regimens and dose reduction of melphalan during conditioning may improve outcomes in this population. In this single center retrospective study, we compared the toxicity and survival outcomes of 96 MM patients with renal insufficiency undergoing ASCT between two eras: 1998-2007 and 2008-2016. The proportion of dialysis dependent patients was similar in both groups (49 and 45%). We found no TRM in those transplanted more recently as compared with 13% in the older era of ASCT. There were significantly more high grade (grades 3-4) toxicities in the older era of ASCT including high grade electrolyte abnormalities, mucositis, delirium, and bleeding. Patients transplanted more recently had significantly higher overall response rate (ORR) as well as deeper responses to ASCT (≥VGPR in 79% vs 39%). Progression-free survival (PFS) was prolonged by 26 months in the more recent era compared with the older era. Overall, improvements in treatment regimens have resulted in reduced TRM and toxicities for patients with renal insufficiency undergoing ASCT.

P14.122 Integrin α5 is a poor prognostic factor in patients with glioblastoma treated by the Stupp protocol

BACKGROUND

Integrin α5β1 was suggested to be involved in glioblastoma (GBM) aggressiveness through preclinical studies and genomic analysis of several cohorts of patients. However, protein expression data are still missing to confirm this hypothesis. Our aim was to investigate the prognostic value of integrin α5 protein expression level in GBM.

MATERIAL AND METHODS

We retrospectively determined the protein expression level of integrin α5 using immunochemistry in tumors from patients treated in 6 French centers. Paraffin sections of GBM were labeled by immunofluorescence and analyzed by confocal microscopy. The corresponding clinical and survival data have been identified and analyzed. The primary end-point was overall survival (OS).

RESULTS

Out of 297 patients newly diagnosed with GBM between 2006 and 2013, 152 met the inclusion criteria (scheduled for initial treatment with the Stupp protocol, age > 18 years) and 95 tumor samples were suitable for immunohistochemical analysis. The median age is 58 years, (64 men, 34 women). Most of patients received macroscopic (43%) or partial (36%) surgery. In univariate analysis using the Log Rank test, high integrin α5 expression level was associated with poor prognosis (PFS: hazard ratio (HR) = 1,696, p=0,0355; OS: HR=1,598, p = 0,0508). Corresponding median OS were 15,6 versus 19,2 months. Similarly, OS was significantly reduced with age (> 60 years), lower resection degree, higher RPA (recursive partitioning analysis) score and non-methylated MGMT (O-6-methylguanine-DNA methyltransferase) promoter. In the subgroup of patients who received the full initial protocol (temozolomide treatment together with radiotherapy and later as adjuvant treatment; n=58) mean OS was strongly reduced when integrin α5 expression level was high (15,6 versus 22,8 months, p=0,0162) suggesting an impact of integrin signaling on temozolomide response in GBM.

CONCLUSION

Our study validates for the first time that the high protein level expression of α5 integrin is associated with poor prognosis in GBM. It also confirms its potential as a therapeutic target and its likely role in resistance to temozolomide as previously shown in preclinical study.

Addition of Cyclophosphamide "On Demand" to Lenalidomide and Corticosteroids in Patients With Relapsed/Refractory Multiple Myeloma-A Retrospective Review of a Single-center Experience

INTRODUCTION

The combination of lenalidomide and dexamethasone (Len-Dex) is an established regimen for patients with relapsed or refractory myeloma. To prolong the benefit of this effective regimen, the Myeloma Program at Princess Margaret Cancer Centre has routinely added a third agent, oral cyclophosphamide (Cy) given weekly, to Len-Dex at disease progression.

PATIENTS AND METHODS

In the present report, we describe the cases of 53 patients who had received Len-Dex-Cy for a minimum of 4 weeks from January 2007 to December 2014 after progression with Len-Dex alone. The dose of added Cy ranged from 250 to 500 mg weekly. The median number of previous regimens, including Len-Dex, was 2 (range, 2-4); 80% of patients had undergone previous autologous stem cell transplantation.

RESULTS

The overall rate of response equal to or greater than a partial response was 34%, and clinical benefit (stable disease or better) was observed in 87% of the patients. The median duration of Len-Dex-Cy therapy was 6.9 months (range, 0.9-55.1 months). The median progression-free survival was 6.1 months (range, 4.2-8.1 months) from the addition of Cy and 24.1 months (range, 15.9-32.0 months) from start of Len-Dex.

CONCLUSION

The addition of Cy for patients with myeloma developing progression with Len-Dex was an inexpensive option with manageable toxicity that resulted in a clinically meaningful extension of disease control.

Targeting B-cell maturation antigen with GSK2857916 antibody-drug conjugate in relapsed or refractory multiple myeloma (BMA117159): a dose escalation and expansion phase 1 trial

BACKGROUND

B-cell maturation antigen (BCMA) is a cell-surface receptor of the tumour necrosis superfamily required for plasma cell survival. BMCA is universally detected on patient-derived myeloma cells and has emerged as a selective antigen to be targeted by novel treatments in multiple myeloma. We assessed the safety, tolerability, and preliminary clinical activity of GSK2857916, a novel anti-BCMA antibody conjugated to microtubule-disrupting agent monomethyl auristatin F, in patients with relapsed and refractory multiple myeloma.

METHODS

We did an international, multicentre, open-label, first-in-human phase 1 study with dose escalation (part 1) and dose expansion (part 2) phases, at nine centres in the USA, Canada, and the UK. Adults with histologically or cytologically confirmed multiple myeloma, Eastern Cooperative Oncology Group performance status 0 or 1, and progressive disease after stem cell transplantation, alkylators, proteasome inhibitors, and immunomodulators were recruited for this study. In part 1, patients received GSK2857916 (0·03-4·60 mg/kg) through 1 h intravenous infusions once every 3 weeks. In part 2, patients received the selected recommended phase 2 dose of GSK2857916 (3·40 mg/kg) once every 3 weeks. Primary endpoints were maximum tolerated dose and recommended phase 2 dose. Secondary endpoints for part 2 included preliminary anti-cancer clinical activity. All patients who received one or more doses were included in this prespecified administrative interim analysis (data cutoff date June 26, 2017), which was done for internal purposes. This study is registered with ClinicalTrials.gov, number NCT02064387, and is ongoing, but closed for recruitment.

FINDINGS

Between July 29, 2014, and Feb 21, 2017, we treated 73 patients: 38 patients in the dose-escalation part 1 and 35 patients in the dose-expansion part 2. There were no dose-limiting toxicities and no maximum tolerated dose was identified in part 1. On the basis of safety and clinical activity, we selected 3·40 mg/kg as the recommended phase 2 dose. Corneal events were common (20 [53%] of 38 patients in part 1 and 22 [63%] of 35 in part 2); most (18 [47%] in part 1 and 19 [54%] in part 2) were grade 1 or 2 and resulted in two treatment discontinuations in part 1 and no discontinuations in part 2. The most common grade 3 or 4 events were thrombocytopenia (13 [34%] of 38 patients in part 1 and 12 [34%] of 35 in part 2) and anaemia (6 [16%] in part 1 and 5 [14%] in part 2). There were 12 treatment-related serious adverse events and no treatment-related deaths. In part 2, 21 (60·0%; 95% CI 42·1-76·1) of 35 patients achieved an overall response.

INTERPRETATION

At the identified recommended phase 2 dose, GSK2857916 was well tolerated and had good clinical activity in heavily pretreated patients, thereby indicating that this might be a promising candidate for the treatment of relapsed or refractory multiple myeloma.

FUNDING

GlaxoSmithKline.

Abstract 5489: Characterization of mitochondrial STAT3 (mitostat3) function and the mitoStat3 interactome as a therapeutic strategy for multiple myeloma

The oncogenic transcription factor STAT3 is an appealing therapeutic target in cancer including multiple myeloma (MM) where its inhibition has the potential to downregulate aberrant signaling from various upstream molecules. STAT3 has been studied extensively as a transcription factor however, much less is known about its non-classical functions in the mitochondria and in turn, the role of mitochondrial STAT3 (mitoStat3) in cancer biology. Data suggests that mitoStat3 is critical for mediating Ras-induced oncogenic transformation. As activating mutations of the MAPK pathway are reported in over 50% of myeloma patients, we sought to characterize the function of mitoStat3 in MM.

We first confirmed the presence of STAT3 in the mitochondria of myeloma cell lines, AMO1 and XG6 by Western blot analysis. We next used CRISPR/CAS9 to knockdown STAT3 in XG6 and AMO1 cells, which resulted in inhibition of cell proliferation (XG6 and AMO1), apoptosis (XG6) and reduced oxygen consumption rate as measured by extracellular flux analysis (Seahorse assay). To better define the role of mitoStat3 and to identify indirect strategies to interfere with STAT3 activity, we employed a proximity-dependent Biotin Identification (BioID) method to discover mitoStat3 interacting proteins. BioID is a unique method to screen for physiologically relevant protein interactions that occur in living cells. First, wild-type STAT3 was fused to a mitochondrial localization Signal (MLS-Stat3), cloned into pcDNA5 FRT/TO [MCS]-BirAR118G-FLAG plasmid and transfected into HEK293 TRE-x Flp-In cells. BioID identified 225 high confidence mitoStat3-interacting partners in MLS-Stat3 transfected cells. The most abundant proteins in the mitoStat3 interactome included those with roles in mitochondrial translation and mitochondrial electron transport. Futhermore, mitoStat3 was found to interact with the translocase of inner membrane protein Tim44, which together with Tim23 complex facilitates translocation of proteins into the mitochondrial matrix. Genetic knockdown of Tim23 in XG6 cells resulted in decreased mitoStat3 suggesting that this complex may be involved in the import of STAT3 into the mitochondria. Additional mitoStat3 interacting proteins identified by BioID are currently being validated and will be presented.

Taken together, results support the further exploration of the role of mitoStat3 in myeloma cells. Further, identification of mitoStat3 interacting proteins including Tim44 and others may inform alternative strategies to therapeutically target oncogenic STAT3.

Citation Format: Serges P. Tsofack, Aaron Botham, Zhihua Li, Ellen Nong Wei, Danielle Croucher, Ioulia Jitkova, Neil MacLean, Aaron D. Schimmer, Brian Raught, Suzanne Trudel. Characterization of mitochondrial STAT3 (mitostat3) function and the mitoStat3 interactome as a therapeutic strategy for multiple myeloma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5489.

A phase 2 study of ofatumumab (Arzerra®) in combination with a pan-AKT inhibitor (afuresertib) in previously treated patients with chronic lymphocytic leukemia (CLL)

AKT plays a centralized role in tumor proliferation and survival and is aberrantly activated in chronic lymphocytic leukemia (CLL). In this phase 2 trial, 30 relapsed/refractory CLL patients were treated with combination afuresertib, a novel oral AKT inhibitor, and ofatumumab for 6 months, followed by afuresertib maintenance for 12 months. We aimed to achieve deeper and more durable responses, without requiring long-term continuous treatment. Treatment was generally well tolerated but respiratory infections were common, with 18% severe requiring hospitalization. Hematologic toxicities were manageable (grade 3-4 neutropenia 39%). At a median follow-up of 13.4 months, overall responses were 50% (complete responses 3.6%). Median progression-free survival was 8.5 months and overall survival 34.8 months. Combination therapy with ofatumumab and afuresertib is active and well tolerated, but does not appear to lead to durable responses and may not provide additional benefit over single-agent ofatumumab in relapsed/refractory CLL. Novel agent combinations are currently undergoing intense investigation.