Management and Outcomes of Patients with Refractory Solitary Plasmacytoma after Treatment with Definitive Radiation Therapy

PURPOSE

Radiation therapy (RT) is the standard treatment for solitary plasmacytoma (SP); however, the optimal management of RT-refractory SPs is unknown. We examined outcomes after early systemic therapy, surgical resection, or observation for patients with RT-refractory disease and assessed the potential impact of treatment selection on disease outcomes.

METHODS AND MATERIALS

We retrospectively reviewed patients with SP treated with definitive radiation and evaluated at a single institution with persistent disease on imaging or biopsy. Descriptive statistics were used to characterize patient and disease characteristics and treatment outcomes.

RESULTS

Of 102 total SP patients, 17 (17%) were RT-refractory. The median RT dose was 45 Gy, and median follow-up was 71 months from end of RT. Fifteen patients had additional treatment for refractory disease at a median time of 9.5 months after RT, with the following subsequent interventions: surgical resection (n = 4), additional RT (n = 2), systemic therapy without evidence of multiple myeloma (MM; n = 4), systemic therapy for progression to MM (n = 5), and observation (n = 2). Of 4 patients treated with surgical resection, 3 progressed to MM 22 to 43 months after diagnosis. Of 2 patients treated with additional RT, neither responded, and both had pathologic confirmation of residual disease after the second course. Four patients treated with systemic therapy without MM all had complete responses on positron emission tomography and no subsequent MM progression. Eight patients were initially observed after RT for ≥12 months (n = 8) or ≥24 months (n = 6). Of the 2 patients in continued observation, both had stable/unchanged avidity after radiation treatment for 12 and 22 months and ultimately had a slow decrease of disease avidity over multiple years.

CONCLUSIONS

Patients with RT-refractory SPs can achieve good local control with alternative therapies, such as surgery or systemic therapy, if needed. Additional RT does not seem to be effective. Given the known high rates of progression from SP to MM, close observation of asymptomatic persistent disease until disease progression is likely sufficient in most cases.

Impact of pretransplant minimal residual disease in patients with multiple myeloma and a very good partial response or better receiving autologous hematopoietic stem cell transplantation

BACKGROUND

The prognostic significance of minimal residual disease (MRD) status before autologous hematopoietic stem cell transplantation (autoHCT) in patients with multiple myeloma (MM) has not been clearly elucidated.

METHODS

Retrospective single-center study of adult MM patients who achieved ≥very good partial response (VGPR) after induction therapy from 2015 to 2021 received upfront autoHCT and had available pretransplant MRD status by next-generation flow cytometry. The cohort was divided into pretransplant MRD-negative (MRDneg) and MRD-positive (MRDpos) groups.

RESULTS

A total of 733 patients were included in our analysis; 425 were MRDneg and 308 MRDpos at autoHCT. In the MRDpos group, more patients had high-risk cytogenetic abnormalities (48% vs. 38%, respectively; p = .025), whereas fewer patients achieved ≥CR before autoHCT (14% vs. 40%; p < .001). At day 100 after autoHCT, 37% of the MRDpos versus 71% of the MRDneg achieved ≥CR, and at best posttransplant response 65% versus 88% achieved ≥CR, respectively. After a median follow-up of 27.6 months (range, 0.7-82.3), the median PFS was significantly shorter for patients in the MRDpos group compared to the MRDneg group: 48.2 months (95% confidence interval [CI], 0.3-80.5) versus 80.1 months (95% CI, 0.5-80.1), respectively (p < .001). There was no significant difference in overall survival between the two groups (p = .41). Pretransplant MRDpos status was predictive of shorter PFS in multivariate analysis (hazard ratio, 1.80; 95% CI, 1.31-2.46; p < .001). The impact of pretransplant MRD status was retained in most of the examined subgroups.

CONCLUSIONS

In patients achieving ≥VGPR to induction, pretransplant MRDpos status was associated with a lower CR rate after autoHCT and a shorter PFS.

Daratumumab-based quadruplet therapy for transplant-eligible newly diagnosed multiple myeloma with high cytogenetic risk

In the MASTER study (NCT03224507), daratumumab+carfilzomib/lenalidomide/dexamethasone (D-KRd) demonstrated promising efficacy in transplant-eligible newly diagnosed multiple myeloma (NDMM). In GRIFFIN (NCT02874742), daratumumab+lenalidomide/bortezomib/dexamethasone (D-RVd) improved outcomes for transplant-eligible NDMM. Here, we present a post hoc analysis of patients with high-risk cytogenetic abnormalities (HRCAs; del[17p], t[4;14], t[14;16], t[14;20], or gain/amp[1q21]). Among 123 D-KRd patients, 43.1%, 37.4%, and 19.5% had 0, 1, or ≥2 HRCAs. Among 120 D-RVd patients, 55.8%, 28.3%, and 10.8% had 0, 1, or ≥2 HRCAs. Rates of complete response or better (best on study) for 0, 1, or ≥2 HRCAs were 90.6%, 89.1%, and 70.8% for D-KRd, and 90.9%, 78.8%, and 61.5% for D-RVd. At median follow-up (MASTER, 31.1 months; GRIFFIN, 49.6 months for randomized patients/59.5 months for safety run-in patients), MRD-negativity rates as assessed by next-generation sequencing (10-5) were 80.0%, 86.4%, and 83.3% for 0, 1, or ≥2 HRCAs for D-KRd, and 76.1%, 55.9%, and 61.5% for D-RVd. PFS was similar between studies and superior for 0 or 1 versus ≥2 HRCAs: 36-month PFS rates for D-KRd were 89.9%, 86.2%, and 52.4%, and 96.7%, 90.5%, and 53.5% for D-RVd. These data support the use of daratumumab-containing regimens for transplant-eligible NDMM with HCRAs; however, additional strategies are needed for ultra-high-risk disease (≥2 HRCAs). Video Abstract.

Health-related quality of life in transplant-eligible patients with newly diagnosed multiple myeloma treated with daratumumab, lenalidomide, bortezomib, and dexamethasone: Patient-reported outcomes from GRIFFIN

In the phase 2 GRIFFIN trial (ClinicalTrials.gov identifier: NCT02874742), daratumumab added to lenalidomide, bortezomib, and dexamethasone (D-RVd) improved depth of response and progression-free survival (PFS) versus lenalidomide, bortezomib, and dexamethasone (RVd) alone in transplant-eligible (TE) patients with newly diagnosed multiple myeloma (NDMM). Here, we present patient-reported outcomes (PROs) collected using the European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire Core 30-item (QLQ-C30), EORTC Quality of Life Questionnaire Multiple Myeloma Module 20-item (QLQ-MY20), and EuroQol 5-Dimension 5-Level (EQ-5D-5L) tools on day 1 of cycles 1, 2, and 3; on day 21 of cycle 4 (end of induction therapy); on day 1 of cycle 5; on day 21 of cycle 6 (end of posttransplant consolidation therapy); and at months 6, 12, 18, and 24 of maintenance therapy. Meaningful improvements from baseline were seen in most of the PRO scales with both treatments after consolidation and were sustained for at least 2 years of maintenance treatment. Large reductions from baseline (~20 points) were especially observed in pain symptoms for both treatment groups, although these were numerically higher for patients receiving D-RVd during the majority of the time points. In addition, improvements in key scales, such as global health status, fatigue symptoms, and physical functioning, were also seen with both D-RVd and RVd. These improvements in health-related quality of life contribute to the totality of evidence supporting the improvement in clinical outcomes such as response rates and PFS with D-RVd in induction, consolidation, and maintenance therapy in TE patients with NDMM.

Impact of revised International Staging System 2 risk stratification on outcomes of patients with multiple myeloma receiving autologous haematopoietic stem cell transplantation

The second revision of the International Staging System (R2-ISS) is a simple tool to risk-stratify newly diagnosed multiple myeloma (NDMM) patients. Here, we completed a retrospective analysis to evaluate the utility of R2-ISS in NDMM patients who underwent up-front autologous haematopoietic stem cell transplantation (auto-HCT). A total of 1291 patients were included, with a median age of 62 years (range 29-83). The distribution of R2-ISS stages was: 123 (10%) stage I, 471 (36%) stage II, 566 (44%) stage III and 131 (10%) stage IV. With a median follow-up of 42.2 months (range 0.3-181.0), the median PFS was 73.0, 65.2, 44.0 and 24.8 months, (p < 0.001) and the median OS was 130.8, 128.5, 94.2 and 61.4 months (p < 0.001) for patients with R2-ISS stages I, II, III and IV respectively. On multivariable analysis (MVA) for PFS, using R2-ISS stage I as reference, R2-ISS stages III (hazard ratio [95% confidence interval], 1.55 [1.05-2.29]; p = 0.028) and IV (2.04 [1.24-3.36]; p = 0.005) were associated with significantly inferior PFS. In the MVA of OS, using R2-ISS stage I as reference, only R2-ISS stage IV was associated with significantly inferior OS (2.43 [1.18-5.01]; p = 0.017). Overall, we found that R2-ISS is a reliable prognostic tool for NDMM patients undergoing up-front auto-HCT.

MUC20 regulated by extrachromosomal circular DNA attenuates proteasome inhibitor resistance of multiple myeloma by modulating cuproptosis

BACKGROUND

Proteasome inhibitors (PIs) are one of the most important classes of drugs for the treatment of multiple myeloma (MM). However, almost all patients with MM develop PI resistance, resulting in therapeutic failure. Therefore, the mechanisms underlying PI resistance in MM require further investigation.

METHODS

We used several MM cell lines to establish PI-resistant MM cell lines. We performed RNA microarray and EccDNA-seq in MM cell lines and collected human primary MM samples to explore gene profiles. We evaluated the effect of MUC20 on cuproptosis of PI-resistant MM cells using Co-immunoprecipitation (Co-IP), Seahorse bioenergetic profiling and in vivo assay.

RESULTS

This study revealed that the downregulation of Mucin 20 (MUC20) could predict PI sensitivity and outcomes in MM patients. Besides, MUC20 attenuated PI resistance in MM cells by inducing cuproptosis via the inhibition of cyclin-dependent kinase inhibitor 2 A expression (CDKN2A), which was achieved by hindering MET proto-oncogene, receptor tyrosine kinase (MET) activation. Moreover, MUC20 suppressed MET activation by repressing insulin-like growth factor receptor-1 (IGF-1R) lactylation in PI-resistant MM cells. This study is the first to perform extrachromosomal circular DNA (eccDNA) sequencing for MM, and it revealed that eccDNA induced PI resistance by amplifying kinesin family member 3 C (KIF3C) to reduce MUC20 expression in MM.

CONCLUSION

Our findings indicated that MUC20 regulated by eccDNA alleviates PI resistance of MM by modulating cuproptosis, which would provide novel strategies for the treatment of PI-resistant MM.

Daratumumab for patients with myeloma with early or late relapse after initial therapy: subgroup analysis of CASTOR and POLLUX

ABSTRACT

High-risk multiple myeloma (MM) is often defined based on cytogenetic abnormalities, but patients who relapse early after initial therapy are considered a functional high-risk group. In the phase 3 CASTOR and POLLUX studies, daratumumab plus bortezomib/dexamethasone (D-Vd) or lenalidomide/dexamethasone (D-Rd) improved progression-free survival (PFS) and overall survival (OS), regardless of cytogenetic risk, and achieved higher rates of complete response or better (≥CR) and minimal residual disease (MRD) negativity vs that with Vd/Rd alone in relapsed/refractory MM. Post hoc analyses of CASTOR and POLLUX evaluated patient subgroups with 1 prior line of therapy based on timing of progression/relapse (early or late) after initiation of first line of therapy. PFS consistently favored the daratumumab-containing regimens across subgroups using both a 24- and 18-month early-relapse cutoff. In the CASTOR/POLLUX pooled data set, daratumumab reduced the risk of disease progression or death by 65% (hazard ratio [HR], 0.35; 95% confidence interval [CI], 0.26-0.48; P < .0001) in the early-relapse (<24 months) subgroup and by 65% (HR, 0.35; 95% CI, 0.26-0.47; P < .0001) in the late-relapse (≥24 months) subgroup. OS also favored the daratumumab-containing regimens in both the early-relapse (HR, 0.62; 95% CI, 0.45-0.86; P = .0036) and late-relapse (HR, 0.67; 95% CI, 0.48-0.93; P = .0183) subgroups in the pooled population using a 24-month cutoff. Rates of ≥CR and MRD negativity (10-5) were higher with daratumumab vs control, regardless of progression/relapse timing. Although daratumumab is unable to fully overcome the adverse prognosis of early relapse, our results support the use of daratumumab for patients with 1 prior line of therapy, including for those who progress/relapse early after initial therapy and are considered to have functional high-risk MM. These trials were registered at www.clinicaltrials.gov as #NCT02136134 (CASTOR) and #NCT02076009 (POLLUX).

Bispecific BCMA/CD24 CAR-T cells control multiple myeloma growth

Anti-multiple myeloma B cell maturation antigen (BCMA)-specific chimeric antigen receptor (CAR) T-cell therapies represent a promising treatment strategy with high response rates in myeloma. However, durable cures following anti-BCMA CAR-T cell treatment of myeloma are rare. One potential reason is that a small subset of minimal residual myeloma cells seeds relapse. Residual myeloma cells following BCMA-CAR-T-mediated treatment show less-differentiated features and express stem-like genes, including CD24. CD24-positive myeloma cells represent a large fraction of residual myeloma cells after BCMA-CAR-T therapy. In this work, we develop CD24-CAR-T cells and test their ability to eliminate myeloma cells. We find that CD24-CAR-T cells block the CD24-Siglec-10 pathway, thereby enhancing macrophage phagocytic clearance of myeloma cells. Additionally, CD24-CAR-T cells polarize macrophages to a M1-like phenotype. A dual-targeted BCMA-CD24-CAR-T exhibits improved efficacy compared to monospecific BCMA-CAR-T-cell therapy. This work presents an immunotherapeutic approach that targets myeloma cells and promotes tumor cell clearance by macrophages.

Novel Anti-B-cell Maturation Antigen Alpha-Amanitin Antibody-drug Conjugate HDP-101 Shows Superior Activity to Belantamab Mafodotin and Enhanced Efficacy in Deletion 17p Myeloma Models

B-cell maturation antigen (BCMA) plays a pathobiologic role in myeloma and is a validated target with five BCMA-specific therapeutics having been approved for relapsed/refractory disease. However, these drugs are not curative, and responses are inferior in patients with molecularly-defined high-risk disease, including those with deletion 17p (del17p) involving the tumor suppressor TP53, supporting the need for further drug development. Del17p has been associated with reduced copy number and gene expression of RNA polymerase II subunit alpha (POLR2A) in other tumor types. We therefore studied the possibility that HDP-101, an anti-BCMA antibody drug conjugate (ADC) with the POLR2A poison α-amanitin could be an attractive agent in myeloma, especially with del17p. HDP-101 reduced viability in myeloma cell lines representing different molecular disease subtypes, and overcame adhesion-mediated and both conventional and novel drug resistance. After confirming that del17p is associated with reduced POLR2A levels in publicly available myeloma patient databases, we engineered TP53 wild-type cells with a TP53 knockout (KO), POLR2A knockdown (KD), or both, the latter to mimic del17p. HDP-101 showed potent anti-myeloma activity against all tested cell lines, and exerted enhanced efficacy against POLR2A KD and dual TP53 KO/POLR2A KD cells. Mechanistic studies showed HDP-101 up-regulated the unfolded protein response, activated apoptosis, and induced immunogenic cell death. Notably, HDP-101 impacted CD138-positive but not-negative primary cells, showed potent efficacy against aldehyde dehydrogenase-positive clonogenic cells, and eradicated myeloma in an in vivo cell line-derived xenograft (CDX). Interestingly, in the CDX model, prior treatment with HDP-101 precluded subsequent engraftment on tumor cell line rechallenge in a manner that appeared to be dependent in part on natural killer cells and macrophages. Finally, HDP-101 was superior to the BCMA-targeted ADC belantamab mafodotin against cell lines and primary myeloma cells in vitro, and in an in vivo CDX. Together, the data support the rationale for translation of HDP-101 to the clinic, where it is now undergoing Phase I trials, and suggest that it could emerge as a more potent ADC for myeloma with especially interesting activity against the high-risk del17p myeloma subtype.

Outcomes of patients with multiple myeloma and 1q gain/amplification receiving autologous hematopoietic stem cell transplant: the MD Anderson cancer center experience

The prognostic impact of additional copies of chromosome 1q (1q + ) on outcomes of newly-diagnosed multiple myeloma (NDMM) patients undergoing autologous transplantation (autoSCT) is unclear. We conducted a retrospective single-center analysis of NDMM patients with 1q21 gain/amplification (3 or ≥4 copies of 1q, respectively) that received autoSCT between 2008-2018. 213 patients were included (79% 1q gain; 21% 1q amplification). The most commonly used induction regimen was bortezomib, lenalidomide, and dexamethasone (41%). At day100 post-autoSCT and at best post-transplant response, 78% and 87% of patients achieved ≥VGPR, and 38% and 50% achieved MRD-negative ≥VGPR, respectively. Median PFS and OS for the entire cohort were 35.5 months and 81.4 months, respectively. On multivariable assessment for PFS, MRD negative ≥VGPR before autoSCT (HR 0.52, p = 0.013) was associated with superior PFS, whereas 1q amplification was associated with inferior PFS (2.03, p = 0.003). On multivariate analysis for OS, achieving MRD negative ≥VGPR at best post-transplant response was associated with superior survival (0.29, p < 0.001), whereas R-ISS III and concomitant del17p or t(4:14) were associated with inferior survival (6.95, p = 0.030, 2.33, p = 0.023 and 3.00, p = 0.047, respectively). In conclusion, patients with 1q+ NDMM, especially 1q amplification, have inferior survival outcomes compared to standard-risk disease after upfront autoSCT, though outcomes are better than other high-risk cytogenetic abnormalities.

Outcomes of Autologous Stem Cell Transplantation in Patients with Ultra-High-Risk Multiple Myeloma

Multiple myeloma (MM) patients with high-risk cytogenetic abnormalities have inferior survival outcomes and are underrepresented in clinical trials. There is scarce data on MM patients with more than one high-risk cytogenetic aberration (ie, ultra- high-risk MM). This study was conducted to evaluate outcomes of newly diagnosed MM patients with ultra-high-risk MM who underwent autologous hematopoietic stem cell transplantation (autoHCT). We conducted a retrospective single-center chart review analysis of adult patients with ultra-high-risk MM who underwent autoHCT between 2008 and 2018 at MD Anderson Cancer Center. High-risk cytogenetics were defined as del(17p), t(4;14), t(14;16), or 1q21 gain or amplification (1q+) by fluorescence in situ hybridization. Primary endpoints were progression-free survival (PFS) and overall survival (OS). Seventy-nine patients with two or more high-risk cytogenetic abnormalities were included in our analysis. The median age of 61 years (range, 33.5 to 76.5 years), and 57% were female. Sixty-seven patients had two high-risk cytogenetic abnormalities, and 12 patients had three high-risk cytogenetic abnormalities. The most common combinations of high-risk abnormalities were [1q+, t(4:14)] (n = 25; 32%) and [1q+, del17p] (n = 21; 27%). The majority of patients received either bortezomib, lenalidomide, and dexamethasone (48%) or carfilzomib, lenalidomide, and dexamethasone (16%) as induction therapy. Prior to autoHCT, 52 patients (66%) achieved a very good partial response or better (≥VGPR), whereas 23 patients (29%) achieved minimal residual disease (MRD)-negative ≥VGPR. Fifty-six patients (71%) received post-transplantation maintenance therapy. Thirty-six patients (46%) achieved MRD-negative ≥VGPR at day +100 after autoHCT, and 40 patients (51%) did so at best post-transplantation response. With a median follow-up in surviving patients of 38.3 months (range, 11.9 to 104.8 months), the median PFS and OS in the entire cohort were 22.9 months and 71.5 months, respectively. For the subset of patients with three HR abnormalities, the median PFS was 15.6 months and median OS was 28.0 months. In multivariate analysis, achieving MRD-negative ≥VGPR prior to autoHCT was associated with improved PFS (hazard ratio [HR], .42; P = .045), whereas male sex (HR, .15; P = .009) and achieving MRD-negative ≥VGPR post-autoHCT (HR, .27; P = .026) were associated with improved OS. In conclusion, patients with ultra-high-risk MM have a median PFS of <24 months with the current standard of care that includes consolidation with autoHCT. These patients may benefit from earlier use of newer treatment modalities, such as chimeric antigen receptor T cell therapy and bispecific antibodies.

Addition of daratumumab to lenalidomide, bortezomib, and dexamethasone for transplantation-eligible patients with newly diagnosed multiple myeloma (GRIFFIN): final analysis of an open-label, randomised, phase 2 trial

BACKGROUND

Addition of daratumumab to lenalidomide, bortezomib, and dexamethasone (D-RVd) in the GRIFFIN study improved the stringent complete response rate by the end of consolidation in transplantation-eligible patients with newly diagnosed multiple myeloma. Here, we report the findings of the predefined final analysis.

METHODS

GRIFFIN was an open-label, randomised, active-controlled, phase 2 trial done in 35 research centres in the USA. Patients had newly diagnosed multiple myeloma with measurable disease by M protein or free light chain, were aged 18-70 years, had an ECOG performance score of 0-2, and were eligible for autologous haematopoietic stem-cell transplantation (HSCT). Patients were randomly assigned (1:1) to four D-RVd or RVd induction cycles, autologous HSCT, two D-RVd or RVd consolidation cycles, and lenalidomide with or without daratumumab maintenance therapy for 2 years. Patients received 21-day cycles of oral lenalidomide (25 mg on days 1-14), subcutaneous bortezomib (1·3 mg/m2 on days 1, 4, 8, and 11), oral dexamethasone (40 mg weekly) with or without intravenous daratumumab (16 mg/kg weekly, cycles 1-4; day 1, cycles 5-6). Maintenance therapy (28-day cycles) was oral lenalidomide (10 mg on days 1-21) with or without daratumumab (16 mg/kg intravenously every 4 or 8 weeks, or 1800 mg subcutaneously monthly). Patients could continue lenalidomide maintenance after study treatment completion. The primary endpoint was stringent complete response rate by the end of consolidation in the response-evaluable population, and has already been reported. Here we report updated stringent complete response rates and secondary outcomes including progression-free survival and overall survival. The trial is registered with ClinicalTrials.gov (NCT02874742) and ended on April 8, 2022.

FINDINGS

Between Dec 20, 2016, and April 10, 2018, 104 patients were randomly assigned to the D-RVd group and 103 were randomly assigned to the RVd group; most patients were White (85 [82%] in the D-RVd group and 76 [74%] in the RVd group) and male (58 [56%] in the D-RVd group and 60 [58%] in the RVd group). At a median follow-up of 49·6 months (IQR 47·4-52·1), D-RVd improved rates of stringent complete response (67 [67%] of 100] vs 47 [48%] of 98]; odds ratio 2·18 [95% CI 1·22-3·89], p=0·0079), and 4-year progression-free survival was 87·2% (95% CI 77·9-92·8) for D-RVd versus 70·0% (95% CI 55·9-80·3) for RVd, with a hazard ratio (HR) of 0·45 (95% CI 0·21-0·95, p=0·032) for risk of disease progression or death with D-RVd. Median overall survival was not reached for either group (HR 0·90 [95% CI 0·31-2·56], p=0·84). The most common grade 3-4 treatment-emergent adverse events in the D-RVd versus RVd groups were neutropenia (46 [46%] of 99 vs 23 [23%] of 102), lymphopenia (23 [23%] vs 23 [23%]), leukopenia (17 [17%] vs eight [8%]), thrombocytopenia (16 [16%] vs nine [9%]), pneumonia (12 [12%] vs 14 [14%]), and hypophosphataemia (ten [10%] vs 11 [11%]). Serious treatment-emergent adverse events occurred in 46 (46%) of 99 patients in the D-RVd group and in 53 (52%) of 102 patients in the RVd group. One patient in each treatment group reported a treatment-emergent adverse event that resulted in death (bronchopneumonia in the D-RVd group; cause unknown in the RVd group); neither was related to study treatment. No new safety concerns occurred with maintenance therapy.

INTERPRETATION

Addition of daratumumab to RVd improved the depth of response and progression-free survival in transplantation-eligible patients with newly diagnosed multiple myeloma. These results justify further evaluation in phase 3 studies.

FUNDING

Janssen Oncology.

Single-agent lenalidomide maintenance after upfront autologous stem cell transplant for newly diagnosed multiple myeloma: The MD Anderson experience

The optimal duration of lenalidomide (Len) maintenance for patients with multiple myeloma (MM) after autologous stem cell transplantation (autoHCT) is unknown. We conducted a retrospective single-center analysis of adult MM patients that received upfront autoHCT between 2005 and 2021, followed by single-agent Len maintenance. A total of 1167 patients were included with a median age of 61.4 (range 25.4-82.3) years, and high-risk chromosomal abnormalities in 19%. Median duration of maintenance was 22.3 (range 0.03-139.6) months. After a median follow-up of 47.9 (range 2.9-171.7) months, median PFS and OS for the entire cohort were 56.6 (95% CI 48.2-61.4) months and 111.3 (95% CI 101.7-121.5) months, respectively. In MVA, high-risk cytogenetics was associated with a worse PFS (HR 1.91) and OS (HR 1.73) (p < .001 for both). Use of KRD induction and achievement of MRD-negative ≥ VGPR before autoHCT were associated with an improved PFS (HR 0.53 and HR 0.57, respectively; p < .001 for both). Longer maintenance duration, even with a 5-year cutoff, was associated with superior PFS and OS (HR 0.17 and 0.12, respectively; p < .001 for both). A total of 106 patients (9%) developed a second primary malignancy (SPM), mostly solid tumors (39%) and myeloid malignancies (30%). Longer maintenance duration was associated with a higher risk of SPM, reaching statistical significance after >2 years (odds ratio 2.25; p < .001). In conclusion, outcomes with Len maintenance were comparable to those reported in large clinical trials. Longer duration of maintenance, even beyond 5 years, was associated with improved survival.

Targeted single-cell proteomic analysis identifies new liquid biopsy biomarkers associated with multiple myeloma

Multiple myeloma (MM) is accompanied by alterations to the normal plasma cell (PC) proteome, leading to changes to the tumor microenvironment and disease progression. There is a great need for understanding the consequences that lead to MM progression and for the discovery of new biomarkers that can aid clinical diagnostics and serve as targets for therapeutics. This study demonstrates the applicability of utilizing the single-cell high-definition liquid biopsy assay (HDSCA) and imaging mass cytometry to characterize the proteomic profile of myeloma. In our study, we analyzed ~87,000 cells from seven patient samples (bone marrow and peripheral blood) across the myeloma disease spectrum and utilized our multiplexed panel to characterize the expression of clinical markers for PC classification, additional potential therapeutic targets, and the tumor microenvironment cells. Our analysis showed BCMA, ICAM3 (CD50), CD221, and CS1 (SLAMF7) as the most abundantly expressed markers on PCs across all myeloma stages, with BCMA, ICAM3, and CD221 having significantly higher expression levels on disease versus precursor PCs. Additionally, we identify significantly elevated levels of expression for CD74, MUM1, CD229, CD44, IGLL5, Cyclin D1, UBA52, and CD317 on PCs from overt disease conditions compared to those from precursor states.

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.).

Outcomes of young adults (aged ≤ 40 years) with newly diagnosed multiple myeloma after up-front autologous stem cell transplant

Multiple myeloma (MM) primarily affects older patients. There are scarce data on the outcomes of young adults undergoing autologous transplantation (auto-HCT). In this single-centre analysis, we included 117 younger patients, with a median age of 37 years (range 22-40) at transplant. Seventeen (15%) patients had high-risk cytogenetics. Before transplant, 10% of patients achieved ≥CR and 44% achieved ≥VGPR. At best post-transplant response, 56% and 77% of patients achieved ≥CR and ≥VGPR respectively. With a median follow-up for survivors of 72.6 months (range 0.9-238.0), median PFS and OS were 43.1 months (95% CI 31.2-65.0) and 146.6 months (95% CI 100.0-208.1) respectively. Patients who underwent auto-HCT after 2010 had better median PFS (84.9 months vs. 28.2 months, p < 0.001) and OS (NR vs. 91.8 months, p < 0.001) compared with those transplanted earlier. In multi-variate analysis, achieving ≥CR as best post-transplant response was associated with improved PFS (HR [95% CI] 0.55 [0.32-0.95], p = 0.032), while achieving ≥VGPR was predictive of superior OS (0.32 [0.16-0.62], p < 0.001). Three patients (3%) developed a second primary malignancy. Younger MM patients had durable survival after auto-HCT, which further improved after the availability of novel anti-myeloma drugs in recent years. Depth of response following transplant remains a key predictor of survival.

Single cell clonotypic and transcriptional evolution of multiple myeloma precursor disease

Multiple myeloma remains an incurable disease, and the cellular and molecular evolution from precursor conditions, including monoclonal gammopathy of undetermined significance and smoldering multiple myeloma, is incompletely understood. Here, we combine single-cell RNA and B cell receptor sequencing from fifty-two patients with myeloma precursors in comparison with myeloma and normal donors. Our comprehensive analysis reveals early genomic drivers of malignant transformation, distinct transcriptional features, and divergent clonal expansion in hyperdiploid versus non-hyperdiploid samples. Additionally, we observe intra-patient heterogeneity with potential therapeutic implications and identify distinct patterns of evolution from myeloma precursor disease to myeloma. We also demonstrate distinctive characteristics of the microenvironment associated with specific genomic changes in myeloma cells. These findings add to our knowledge about myeloma precursor disease progression, providing valuable insights into patient risk stratification, biomarker discovery, and possible clinical applications.

Clinicopathologic Features of Therapy-Related Myeloid Neoplasms in Patients with Myeloma in the Era of Novel Therapies

The development of therapy-related myeloid neoplasms (t-MN) is a rare complication that can occur in myeloma patients treated primarily with novel therapies. To better understand t-MNs in this context, we reviewed 66 such patients and compared them with a control group of patients who developed t-MN after cytotoxic therapies for other malignancies. The study group included 50 men and 16 women, with a median age of 68 years (range, 48-86 years). Therapies included proteasome inhibitors, immunomodulatory agents, and high-dose melphalan-based autologous stem cell transplantation (HDM-ASCT) in 64 (97%), 65 (98.5%), and 64 (97%) patients, respectively; 29 (43.9%) patients were exposed to other cytotoxic drugs besides HDM. The latency interval from therapy to t-MN was 4.9 years (range, 0.6-21.9 years). Patients who received HDM-ASCT in addition to other cytotoxic therapies had a longer latency period to t-MN compared with patients who only received HDM-ASCT (6.1 vs 4.7 years, P = .009). Notably, 11 patients developed t-MN within 2 years. Therapy-related myelodysplastic syndrome was the most common type of neoplasm (n = 60), followed by therapy-related acute myeloid leukemia (n = 4) and myelodysplastic syndrome/myeloproliferative neoplasm (n = 2). The most common cytogenetic aberrations included complex karyotypes (48.5%), del7q/-7 (43.9%), and/or del5q/-5 (40.9%). The most frequent molecular alteration was TP53 mutation, in 43 (67.2%) patients and the sole mutation in 20 patients. Other mutations included DNMT3A, 26.6%; TET2, 14.1%; RUNX1, 10.9%; ASXL1, 7.8%; and U2AF1, 7.8%. Other mutations in less than 5% of cases included SRSF2, EZH2, STAG2, NRAS, SETBP, SF3B1, SF3A1, and ASXL2. After a median follow-up of 15.3 months, 18 patients were alive and 48 died. The median overall survival after the diagnosis of t-MN in the study group was 18.4 months. Although the overall features are comparable to the control group, the short interval to t-MN (<2 years) underscores the unique vulnerable status of myeloma patients.

Plain language summary of the MAIA study of daratumumab plus lenalidomide and dexamethasone for the treatment of people with newly diagnosed multiple myeloma

WHAT IS THIS SUMMARY ABOUT?

This is a summary of a clinical trial called MAIA. The trial tested 2 combinations of cancer drugs (daratumumab plus lenalidomide and dexamethasone compared with lenalidomide and dexamethasone) in people with newly diagnosed multiple myeloma. None of the participants who took part in the study had been treated before or were eligible to receive stem-cell transplants.

HOW WAS THE STUDY IN THIS SUMMARY CONDUCTED?

A total of 737 participants took part. Half of the participants took daratumumab plus lenalidomide and dexamethasone, while the other half of the participants took only lenalidomide and dexamethasone. Once participants started taking the drugs, the cancer was monitored for improvement (response to treatment), worsening (disease progression), or no change. Participants' blood and urine were tested for myeloma protein to measure response to the treatment. Participants were also monitored for side effects.

WHAT WERE THE RESULTS OF THE STUDY?

After approximately 56 months of follow-up, more participants who took daratumumab plus lenalidomide and dexamethasone were alive and had decreased myeloma protein levels (indicating improvement of cancer) than participants who took only lenalidomide and dexamethasone. The most common side effects were abnormally low white and red blood cell counts and increased lung infections.

WHAT DO THE RESULTS OF THE STUDY MEAN?

In the MAIA study, participants with multiple myeloma who took daratumumab plus lenalidomide and dexamethasone lived longer and had decreased myeloma protein levels than participants who took only lenalidomide and dexamethasone, indicating survival could be more likely with daratumumab added. Clinical Trial Registration: NCT02252172 (Phase 3 MAIA study).

Impact of clonal plasma cells in autografts on outcomes in high-risk multiple myeloma patients

Most patients with multiple myeloma (MM) undergoing autologous hematopoietic stem cell transplantation (autoHCT) eventually relapse, perhaps due to the presence of clonal plasma cells (CPC) in the autograft. We conducted a retrospective analysis to evaluate the impact of CPC in the autograft on the outcomes of high-risk chromosomal abnormalities (HRMM) patients undergoing autoHCT between 2008 and 2018. Patients were divided into CPC+ or CPC- in the autograft by next-generation flow cytometry (NGF). There were 75 CPC + autografts (18%) and 341 CPC- (82%). The CPC + group was less likely to achieve MRD-negative complete remission post-transplant (11% vs. 42%; p < 0.001). Median progression free survival (PFS) and overall survival (OS) were (12.8 vs. 32.1 months) and (36.4 vs. 81.2 months) in the CPC + and CPC- groups, respectively (both p < 0.001). Also in the subset of patients with MRD-negative ≥VGPR prior to autoHCT, those with CPC + autografts had inferior PFS (HR 4.21, p = 0.006) and OS (HR 7.04, p = 0.002) compared to CPC-. In multivariable analysis, the degree of CPC positivity in the autograft was independently predictive of worse PFS (HR 1.50, p = 0.001) and OS (HR 1.37, p = 0.001). In conclusion, both the presence and degree of CPC in the autograft were highly predictive of inferior PFS and OS.

Antibody-Drug Conjugates for Multiple Myeloma: Just the Beginning, or the Beginning of the End?

Multiple myeloma is a malignancy of immunoglobulin-secreting plasma cells that is now often treated in the newly diagnosed and relapsed and/or refractory settings with monoclonal antibodies targeting lineage-specific markers used either alone or in rationally designed combination regimens. Among these are the anti-CD38 antibodies daratumumab and isatuximab, and the anti-Signaling lymphocytic activation molecule family member 7 antibody elotuzumab, all of which are used in their unconjugated formats. Single-chain variable fragments from antibodies also form a key element of the chimeric antigen receptors (CARs) in the B-cell maturation antigen (BCMA)-targeted CAR T-cell products idecabtagene vicleucel and ciltacabtagene autoleucel, which are approved in the advanced setting. Most recently, the bispecific anti-BCMA and T-cell-engaging antibody teclistamab has become available, again for patients with relapsed/refractory disease. Another format into which antibodies can be converted to exert anti-tumor efficacy is as antibody-drug conjugates (ADCs), and belantamab mafodotin, which also targets BCMA, represented the first such agent that gained a foothold in myeloma. Negative results from a recent Phase III study have prompted the initiation of a process for withdrawal of its marketing authorization. However, belantamab remains a drug with some promise, and many other ADCs targeting either BCMA or other plasma cell surface markers are in development and showing potential. This contribution will provide an overview of some of the current data supporting the possibility that ADCs will remain a part of our chemotherapeutic armamentarium against myeloma moving forward, and also highlight areas for future development.

Abstract 775: Integrative genomic and transcriptomic profiling of myeloma precursors in a prospective longitudinal observational study (ORIGIN)

Background: Monoclonal gammopathy of undetermined significance (MGUS) and smoldering myeloma (SMM) are myeloma precursors (MPD). A better understanding of the oncogenic/immune programs underlying progression may reveal exploitable targets for patients (pts) at high risk of progression and aid new intervention strategies. We designed a longitudinal Observational prospective Research study In monoclonal Gammopathies leadINg to myeloma (ORIGIN) to collect well-annotated, longitudinal samples (sps) for integrative genomic/transcriptomic analysis.

Methods: Pts were accrued meeting MGUS/SMM IMWG definition. BM sps were partitioned into CD138-positive and -negative compartments and DNAs/RNAs extracted for bulk RNA and whole-exome sequencing (WES). Matched germline controls were included for somatic mutation and DNA copy number analysis. A number of tools and algorithms were applied, and the data were thoroughly analyzed and integrated.

Results: From 12/2015-03/2022, 249 pts were accrued and 205 eligible (99 MGUS/106 SMM). Median follow up time is 33 months (6-49 months). As of 11/2022, 21 pts progressed (prog) on ORIGIN study (14% 15/106 SMM, 3% 3/99 prog to SMM from MGUS and 1% 3/205 to AL amyloidosis). To increase analytic power, genomic data of 166 SMM baseline sps from SMM pts on treatment studies were added. Altogether, genomic data of 496 sps were analyzed. Briefly, WES was performed on 170 sps from 150 pts and RNA-Seq was performed on enriched tumor/TME cells in 326 sps from 187 pts. Relative to MGUS, we observed higher mutation load in SMM and more frequent somatic mutations in known drivers of myeloma: KRAS (14% vs. 2%), NRAS (7% vs. 2%) leading to a shorter time to myeloma as well as genes recurrently mutated in other cancers: FOXO3 (7% vs 0%). We observed increased aneuploidy levels in SMM vs MGUS and in prog vs. non-prog including both gains and losses of multiple chromosomes. Transcriptome analysis of CD138+ cells revealed clearly distinct expression profiles between SMM and MGUS, and between prog and non-prog. The pathway activity of oxidative phosphorylation and MYC was significantly increased in SMM vs. MGUS and in prog vs. non-prog, suggesting their potential roles in driving progression. We noted a greater degree of heterogeneity in TME cell compositions in SMM vs MGUS sps and in prog vs. non-prog: ie, SMM and prog sps formed multiple distinct clusters exhibiting differential abundance of cytotoxic T cells, neutrophils, fibroblasts and myeloid cells.

Conclusions: Together, our integrative analysis of genomic and transcriptome data in ORIGIN demonstrates extensive changes in both CD138+ cells and the immune microenvironment and co-evolution of the ecosystems during disease progression. This study is an invaluable resource and lays the molecular foundation for the community for future biomarker and target discovery.

Citation Format: Minghao Dang, Chutima Kunacheewa, Hans C. Lee, Krina K. Patel, Sheeba K. Thomas, Melody Becnel, Donna M. Weber, Pei Lin, Zuzana Berkova, Mei Huang, David A. Berrios, Hima Bansal, Andrew Futreal, Cristhiam Rojas Hernandez, Vahid Afshar-Khargan, Michael Kroll, Peter Kuhn, Robert Z. Orlowski, Linghua Wang, Elisabet E. Manasanch. Integrative genomic and transcriptomic profiling of myeloma precursors in a prospective longitudinal observational study (ORIGIN) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 775.

Abstract 5579: Single cell characterization of circulating plasma cells and BCMA levels in patients with multiple myeloma

Multiple myeloma (MM), a disease caused by the clonal proliferation of plasma cells (PCs), is the second leading hematologic malignancy in the world, with a global incidence rate increase of 126% and mortality rate increasing by 94% in the past decade. Recently, B cell maturation antigen (BCMA) has emerged as a promising biomarker and therapeutic target for MM due to its selective high expression on malignant PCs, improving the treatment landscape. However, the current diagnostic workup relies on bone marrow aspirates (BMA) which are highly invasive and do not allow for the detection of BCMA levels on circulating PCs, severely limiting the options for repeatable assessments and treatment-monitoring. In our study, we report the utility of a blood-based liquid biopsy, using enrichment-free high definition single cell assay (HDSCA) for the detection, quantification, and morphological characterization of circulating PCs and other BCMA+ cells. We applied a previously validated 4-color immunofluorescence assay using DAPI, CD138, BCMA, and CD45 to examine matched peripheral blood and BMAs from 68 patients across the MM disease spectrum (11 monoclonal gammopathy of undetermined significance [MGUS], 21 smoldering MM [SMM], 18 newly diagnosed MM, and 18 relapsed refractory MM [RRMM]) and peripheral blood from 23 normal donors as controls. Our analysis revealed diverse subtypes of circulating CD138(+/-), BCMA(+/-), and CD45(+/-) cells across the patients, representing both normal and abnormal PCs. We detected significantly higher circulating CD138+ BCMA(+/-) cells in MM precursor conditions (MGUS, SMM), compared to the normal donors. Additionally, we were able to detect BCMA+ oncosomes (identified by the lack of a nuclear structure) in the circulation of patients from both precursor and overt disease conditions. Our findings establish the utility of HDSCA blood-based liquid biopsy for early disease detection and anti-BCMA therapy response monitoring in MM and other B-cell malignancies expressing BCMA.

Citation Format: Sonia Maryam Setayesh, Stephanie Shishido, Libere Ndacayisaba, Amin Naghdloo, Jeremy Mason, Dean Tessone, Carli Kaleta, Robert Z. Orlowski, Elisabet E. Manasanch, James Hicks, Peter Kuhn. Single cell characterization of circulating plasma cells and BCMA levels in patients with multiple myeloma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5579.

Autologous Stem Cell Transplantation for Patients with Multiple Myeloma with Translocation (4;14): The MD Anderson Cancer Center Experience

Translocation between chromosomes 4 and 14, t(4;14), has been reported in 15% of patients with multiple myeloma (MM) and is considered a high-risk cytogenetic abnormality associated with inferior outcomes. Autologous hematopoietic stem cell transplantation (auto-HCT) is standard of care for patients with high-risk MM, yet there are scarce data on post-transplantation outcomes of patients with t(4;14) MM. The aim of the present study was to evaluate outcomes of MM patients with t(4;14) who underwent auto-HCT and received contemporary anti-myeloma agents for induction and post-transplantation maintenance. We conducted a retrospective analysis of MM patients with t(4;14), detected by fluorescence in situ hybridization (FISH), who underwent auto-HCT between 2008 and 2018 at MD Anderson Cancer Center. Primary endpoints were progression-free survival (PFS) and overall survival (OS), and secondary endpoints were hematologic response and minimal residual disease (MRD) status after auto-HCT. MRD status in the bone marrow biopsy was evaluated using 8-color next-generation flow cytometry with a sensitivity of 1/10-5 cells. Seventy-nine patients were included (52% male), with a median age of 60 years (range, 32 to 78 years). Forty-four patients (56%) had an additional high-risk cytogenetic abnormality. Fifty patients (63%) achieved at least a very good partial response (≥VGPR) prior to auto-HCT and 20 (25%) had MRD-negative ≥VGPR. At the best post-transplantation evaluation, 90% had ≥VGPR and 63% had MRD-negative ≥VGPR. The median follow-up for survivors was 35.7 months (range, 7.7 to 111.6 months). For the entire cohort, median PFS and OS were 22.9 months and 60.4 months, respectively. Patients with MRD-negative ≥VGPR prior to transplantation had improved PFS and OS on both univariate analysis (UVA) and multivariate analysis (MVA) (hazard ratio [HR], .35 [95% confidence interval (CI), .16 to .76; P = .008] and .12 [95% CI, .03 to .44; P = .002], respectively). The presence of additional high-risk cytogenetic abnormalities was not associated with inferior PFS (P = .57) or OS (P = .70). Post-transplantation lenalidomide-based combinations were associated with improved OS in both UVA and MVA (HR, .14; 95% CI, .04 to .45; P = .001), while their impact on PFS was not statistically significant (P = .37). Our results consolidate t(4;14) as a high-risk abnormality associated with poor outcomes despite novel agent induction, auto-HCT, and post-transplantation maintenance. Despite some inherent study design limitations, including a relatively small cohort and heterogeneity in treatment, we observed that deeper pretransplantation response and post-transplantation maintenance with lenalidomide-based combination were associated with improved outcomes. Novel immune and cellular therapies are needed to improve the outcomes in patients with t(4;14).

Hyperfractionated Cyclophosphamide and Dexamethasone Alone or in Combination with Daratumumab and/or Carfilzomib for the Treatment of Relapsed or Refractory Multiple Myeloma: A Single-Center Retrospective Analysis

BACKGROUND

Hyperfractionated cyclophosphamide and dexamethasone (HyperCd) alone, or with carfilzomib(K) and/or daratumumab(D), represents a potential treatment option when rapid disease control is needed for patients with aggressive presentations of relapsed/refractory multiple myeloma (RRMM).

PATIENTS AND METHODS

This is a single-center, retrospective analysis of adult patients with RRMM who received HyperCd with or without K and/or D between May 1, 2016 and August 1, 2019 at the University of Texas MD Anderson Cancer Center. We here report treatment response and safety outcomes.

RESULTS

Data from 97 patients, 12 with plasma cell leukemia (PCL), were reviewed in this analysis. Patients had had a median of 5 prior lines of therapy and received a median of 1 consecutive cycle of hyperCd-based therapy. The overall response rate (ORR) of all patients was 71.8% (HyperCd 75%, HyperCdK 64.3%, D-HyperCd 73.3%, and D-HyperCdK 76.9%). Median progression-free survival and overall survival among all patients was 4.3 months (HyperCd 3.1 months, HyperCdK 4.5 months, D-HyperCd 3.3 months, and D-HyperCdK 6 months) and 9.0 months (HyperCd 7.4 months, HyperCdK 9.0 months, D-HyperCd 7.5 months, and D-HyperCdK 15.2 months), respectively. Grade 3/4 hematologic toxicities were common, thrombocytopenia being the most frequent at 76%. Notably, 29-41% of patients per treatment group had existing grade 3/4 cytopenias at initiation of hyperCd-based therapy.

CONCLUSION

HyperCd-based regimens provided rapid disease control among MM patients, even when heavily pre-treated and with few remaining treatment options. Grade 3/4 hematologic toxicities were frequent, but manageable with aggressive supportive care.

Long-Term Outcomes of Allogeneic Hematopoietic Cell Transplantation in Patients with Newly Diagnosed Multiple Myeloma

Despite remarkable progress in survival with the availability of novel agents, an overwhelming majority of patients with multiple myeloma (MM) have disease that relapses. Allogeneic (allo-) hematopoietic cell transplantation (HCT) is a potentially curative option for a subgroup of patients with high-risk MM. This study assessed the long-term outcome of MM patients who underwent allo-HCT while in first remission as consolidation treatment. Thirty-three patients with newly diagnosed MM who underwent allo-HCT as part of consolidation therapy between 1994 and 2016 were reviewed retrospectively. Of these patients, 70% underwent autologous HCT before allo-HCT. All patients were chemosensitive and achieved at least partial response before proceeding to allo-HCT. Most received nonmyeloablative/reduced-intensity conditioning (88%) and a matched sibling donor graft (85%). Acute graft-versus-host disease (GVHD) and chronic GVHD occurred in 30% and 61% of patients, respectively. The median duration of follow-up was 64.1 months (range, 1.4 to 199.2 months) for all patients and 164.4 months (range, 56.0 to 199.2 months) for survivors. The median progression-free survival (PFS) was 36 months (95% confidence interval (CI), 8.6 to 73.0 months). The median time from treatment to progression was 73.0 months (95% CI, 30.6 months to not reached). The median overall survival (OS) was 131.9 months (95% CI, 38.4 months to not reached). Of all patients, 39% were alive for more than 10 years, with 46% (n = 6) without progression or relapse. The cumulative incidence of relapse was 18% at 1 year, 39% at 5 years, and 46% at 10 years post-allo-HCT. The cumulative incidence of nonrelapse mortality was 3% at 100 days, 18% at 1 year, 21% at 3 years, and 24% at 5 year post-allo-HCT. On multivariable analysis, high-risk cytogenetics were associated with a shorter PFS (hazard ratio [HR], 2.7; 95% CI, 1.01 to 7.21; P = .047) and OS (HR, 4.91; 95% CI, 1.48 to 16.27; P = .009). Achieving complete remission after allo-HCT also was associated with longer PFS (HR, 0.24; 95% CI, 0.09 to 0.64; P = .004) and OS (HR, .23; 95% CI, .07 to .72; P = .012). Allo-HCT may confer a survival advantage in a selected population of MM patients when performed early in the disease course; additional data on identifying the patients who will benefit the most are needed.

Overall Survival With Daratumumab, Lenalidomide, and Dexamethasone in Previously Treated Multiple Myeloma (POLLUX): A Randomized, Open-Label, Phase III Trial

PURPOSE

With the initial analysis of POLLUX at a median follow-up of 13.5 months, daratumumab in combination with lenalidomide and dexamethasone (D-Rd) significantly prolonged progression-free survival versus lenalidomide and dexamethasone (Rd) alone in patients with relapsed or refractory multiple myeloma (RRMM). We report updated efficacy and safety results at the time of final analysis for overall survival (OS).

METHODS

POLLUX was a multicenter, randomized, open-label, phase III study during which eligible patients with ≥ 1 line of prior therapy were randomly assigned 1:1 to D-Rd or Rd until disease progression or unacceptable toxicity. After positive primary analysis and protocol amendment, patients receiving Rd were offered daratumumab monotherapy after disease progression.

RESULTS

Significant OS benefit was observed with D-Rd (hazard ratio, 0.73; 95% CI, 0.58 to 0.91; P = .0044) at a median (range) follow-up of 79.7 months (0.0-86.5). The median OS was 67.6 months for D-Rd compared with 51.8 months for Rd. Prespecified analyses demonstrated an improved OS with D-Rd versus Rd in most subgroups, including patients age ≥ 65 years and patients with one, two, or three prior lines of therapy, International Staging System stage III disease, high-risk cytogenetic abnormalities, and refractoriness to their last prior line of therapy or a proteasome inhibitor. The most common (≥ 10%) grade 3/4 treatment-emergent adverse events with D-Rd versus Rd were neutropenia (57.6% v 41.6%), anemia (19.8% v 22.4%), pneumonia (17.3% v 11.0%), thrombocytopenia (15.5% v 15.7%), and diarrhea (10.2% v 3.9%).

CONCLUSION

D-Rd significantly extended OS versus Rd alone in patients with RRMM. To our knowledge, for the first time, our findings, together with the OS benefit observed with daratumumab plus bortezomib and dexamethasone in the phase III CASTOR trial, demonstrate OS improvement with daratumumab-containing regimens in RRMM (ClinicalTrials.gov identifier: NCT02076009 [POLLUX]).

Stem Cell Mobilization Yields with Daratumumab- and Lenalidomide-Containing Quadruplet Induction Therapy in Newly Diagnosed Multiple Myeloma: Findings from the MASTER and GRIFFIN Trials

For eligible patients with newly diagnosed multiple myeloma (NDMM), standard of care includes induction therapy followed by autologous stem cell transplantation (ASCT). Daratumumab as monotherapy and in combination treatment is approved across multiple lines of therapy for multiple myeloma (MM), and lenalidomide is an effective and commonly used agent for induction and maintenance therapy in MM. However, there is concern that lenalidomide and daratumumab given as induction therapy might impair mobilization of stem cells for ASCT. Therefore, we assessed stem cell mobilization in patients following frontline induction therapy in the MASTER and GRIFFIN phase 2 clinical studies by examining stem cell mobilization yields, apheresis attempts, and engraftment outcomes for patients from each study. Adult transplantation-eligible patients with NDMM received induction therapy consisting of daratumumab plus carfilzomib/lenalidomide/dexamethasone (D-KRd) for four 28-day cycles in the single-arm MASTER trial or lenalidomide/bortezomib/dexamethasone (RVd) with or without daratumumab (D) for four 21-day cycles in the randomized GRIFFIN trial, followed by stem cell mobilization and ASCT in both studies. Institutional practice differed regarding plerixafor use for stem cell mobilization; the strategies were upfront (ie, planned plerixafor use) or rescue (ie, plerixafor use only after mobilization parameters indicated failure with granulocyte colony-stimulating factor [G-CSF] alone). Descriptive analyses were used to summarize patient characteristics, stem cell mobilization yields, and engraftment outcomes. In MASTER, 116 D-KRd recipients underwent stem cell mobilization and collection at a median of 24 days after completing induction therapy. In GRIFFIN, 175 patients (D-RVd, n = 95; RVd, n = 80) underwent mobilization at a median of 27 days after completing D-RVd induction therapy and 24 days after completing RVd induction therapy. Among those who underwent mobilization and collection, 7% (8 of 116) of D-KRd recipients, 2% (2 of 95) of D-RVd recipients, and 6% (5 of 80) of RVd recipients did not meet the center-specific minimally required CD34⁺ cell yield in the first mobilization attempt; however, nearly all collected sufficient stem cells for ASCT on remobilization. Among patients who underwent mobilization, plerixafor use, either upfront or as a rescue strategy, was higher in patients receiving D-KRd (97%; 112 of 116) and D-RVd (72%; 68 of 95) compared with those receiving RVd (55%; 44 of 80). The median total CD34⁺ cell collection was 6.0 × 10⁶/kg (range, 2.2 to 13.9 × 10⁶/kg) after D-KRd induction, 8.3 × 10⁶/kg (range, 2.6 to 33.0 × 10⁶/kg) after D-RVd induction, and 9.4 × 10⁶/kg (range, 4.1 to 28.7 × 10⁶/kg) after RVd induction; the median days for collection were 2, 2, and 1, respectively. Among patients who underwent mobilization, 98% (114 of 116) of D-KRd patients, 99% (94 of 95) of D-RVd patients, and 98% (78 of 80) of RVd patients underwent ASCT using median CD34⁺ cell doses of 3.2 × 10⁶/kg, 4.2 × 10⁶/kg, and 4.8 × 10⁶/kg, respectively. The median time to neutrophil recovery was 12 days in all 3 treatment groups across the 2 trials. Because both trials used different criteria to define platelet recovery, data on platelet engraftment using the same criteria are not available. Four cycles of daratumumab- and lenalidomide-based quadruplet induction therapy had a minimal impact on stem cell mobilization and allowed predictable stem cell harvesting and engraftment in all patients who underwent ASCT. Upfront plerixafor strategy may be considered, but many patients were successfully collected with the use of G-CSF alone or rescue plerixafor.

A pleiotropic variant in DNAJB4 is associated with multiple myeloma risk

Pleiotropy, which consists of a single gene or allelic variant affecting multiple unrelated traits, is common across cancers, with evidence for genome-wide significant loci shared across cancer and noncancer traits. This feature is particularly relevant in multiple myeloma (MM) because several susceptibility loci that have been identified to date are pleiotropic. Therefore, the aim of this study was to identify novel pleiotropic variants involved in MM risk using 28 684 independent single nucleotide polymorphisms (SNPs) from GWAS Catalog that reached a significant association (P < 5 × 10^-8 ) with their respective trait. The selected SNPs were analyzed in 2434 MM cases and 3446 controls from the International Lymphoma Epidemiology Consortium (InterLymph). The 10 SNPs showing the strongest associations with MM risk in InterLymph were selected for replication in an independent set of 1955 MM cases and 1549 controls from the International Multiple Myeloma rESEarch (IMMEnSE) consortium and 418 MM cases and 147 282 controls from the FinnGen project. The combined analysis of the three studies identified an association between DNAJB4-rs34517439-A and an increased risk of developing MM (OR = 1.22, 95%CI 1.13-1.32, P = 4.81 × 10^-7 ). rs34517439-A is associated with a modified expression of the FUBP1 gene, which encodes a multifunctional DNA and RNA-binding protein that it was observed to influence the regulation of various genes involved in cell cycle regulation, among which various oncogenes and oncosuppressors. In conclusion, with a pleiotropic scan approach we identified DNAJB4-rs34517439 as a potentially novel MM risk locus.

Radiation Therapy Can Be Safely Incorporated into Pretransplantation Treatment Regimens for Patients with Multiple Myeloma

Primary treatment of multiple myeloma (MM) often involves systemic induction therapy (SIT) followed by autologous stem cell transplantation (ASCT). Radiation therapy (RT) is sometimes used for palliation; however, many practitioners avoid RT out of concern that future peripheral blood progenitor cell (PBPC) collection required for ASCT may be compromised. In this study, we retrospectively examined the possible effect of RT on PBPC collection. We reviewed the charts of 732 patients with MM treated with RT at our institution from 1999 to 2017, including patients who received RT prior to PBPC collection for planned ASCT. RT plans (both MM and non-MM RT) were reviewed to estimate the percentage of bone marrow (BM) treated using published estimates of skeletal BM distribution. Statistics were performed using Pearson correlation and the t-test. The 732 MM patients included 485 planned for ASCT; of these, 223 received RT prior to PBPC collection and were included in the final cohort. The median age at PBPC collection was 59 years (range, 33 to 80 years). For SIT, patients received combination regimens including the following agents: bortezomib (142 patients; 64%), lenalidomide (111 patients; 50%), and alkylators (46 patients; 21%). Nine patients (4%) received dexamethasone alone. The median cumulative %BM treated per patient was 6.7 (range .0 to 47.4). The median RT dose was 24 Gy (range, 10.0 to 75.6 Gy). Mobilization was performed using granulocyte-colony stimulating factor (G-CSF) alone (189 patients; 85%), G-CSF with plerixafor (15 patients; 7%), or chemotherapy (19 patients; 9%). A median of 7.8 × 106 CD34+/kg PBPCs (range, .5 to 54.8× 106 CD34+/kg) were collected in a median of 3 (range, 1 to 9) apheresis procedures. One hundred ninety-six patients (99%) collected ≥2.0 × 106 CD34+/kg PBPCs, and 166 (83%) collected >5.0 × 106 CD34+/kg PBPCs. The number of PBPCs collected was not associated with %BM treated (P = .15) or RT dose (P = .56). The number of apheresis procedures performed was not associated with %BM treated (P = .54) or RT dose (P = .85). The amount of PBPCs collected did not differ significantly between patients receiving RT to the pelvis/sacrum (P = .20) and those receiving RT to the spine (P = .13). The time to platelet engraftment was longer for patients with higher %BM treated (P = .02). Eleven patients did not undergo a confirmed ASCT, owing to patient preference (3 patients), trial therapy (1 patient), comorbidities (1 patient), election for hospice (1 patient), inadequate collection (4 patients), or inadequate follow-up (1 patient). In our study cohort, RT prior to ASCT did not impair successful ASCT. RT must be carefully planned and delivered to ensure safe incorporation into pre-ASCT treatment regimens.

Triplet Therapy, Transplantation, and Maintenance until Progression in Myeloma

BACKGROUND

In patients with newly diagnosed multiple myeloma, the effect of adding autologous stem-cell transplantation (ASCT) to triplet therapy (lenalidomide, bortezomib, and dexamethasone [RVD]), followed by lenalidomide maintenance therapy until disease progression, is unknown.

METHODS

In this phase 3 trial, adults (18 to 65 years of age) with symptomatic myeloma received one cycle of RVD. We randomly assigned these patients, in a 1:1 ratio, to receive two additional RVD cycles plus stem-cell mobilization, followed by either five additional RVD cycles (the RVD-alone group) or high-dose melphalan plus ASCT followed by two additional RVD cycles (the transplantation group). Both groups received lenalidomide until disease progression, unacceptable side effects, or both. The primary end point was progression-free survival.

RESULTS

Among 357 patients in the RVD-alone group and 365 in the transplantation group, at a median follow-up of 76.0 months, 328 events of disease progression or death occurred; the risk was 53% higher in the RVD-alone group than in the transplantation group (hazard ratio, 1.53; 95% confidence interval [CI], 1.23 to 1.91; P<0.001); median progression-free survival was 46.2 months and 67.5 months. The percentage of patients with a partial response or better was 95.0% in the RVD-alone group and 97.5% in the transplantation group (P = 0.55); 42.0% and 46.8%, respectively, had a complete response or better (P = 0.99). Treatment-related adverse events of grade 3 or higher occurred in 78.2% and 94.2%, respectively; 5-year survival was 79.2% and 80.7% (hazard ratio for death, 1.10; 95% CI, 0.73 to 1.65).

CONCLUSIONS

Among adults with multiple myeloma, RVD plus ASCT was associated with longer progression-free survival than RVD alone. No overall survival benefit was observed. (Funded by the National Heart, Lung, and Blood Institute and others; DETERMINATION ClinicalTrials.gov number, NCT01208662.).

Perspectives on the Risk-Stratified Treatment of Multiple Myeloma

The multiple myeloma treatment landscape has changed dramatically. This change, paralleled by an increase in scientific knowledge, has resulted in significant improvement in survival. However, heterogeneity remains in clinical outcomes, with a proportion of patients not benefiting from current approaches and continuing to have a poor prognosis. A significant proportion of the variability in outcome can be predicted on the basis of clinical and biochemical parameters and tumor-acquired genetic variants, allowing for risk stratification and a more personalized approach to therapy. This article discusses the principles that can enable the rational and effective development of therapeutic approaches for high-risk multiple myeloma.

Does a Multiple Myeloma Polygenic Risk Score Predict Overall Survival of Myeloma Patients?

BACKGROUND

Genome-wide association studies (GWAS) of multiple myeloma (MM) in populations of European ancestry (EA) identified and confirmed 24 susceptibility loci. For other cancers (e.g. colorectum and melanoma), risk loci have also been associated with patient survival.

METHODS

We explored the possible association of all the known risk variants and their polygenic risk score (PRS) with MM overall survival (OS) in multiple populations of EA (IMMEnSE consortium, InterLymph consortium, CoMMpass and the German GWAS) for a total of 3748 MM cases. Cox proportional hazards regression was used to assess the association between each risk SNP with OS under the allelic and codominant models of inheritance. All analyses were adjusted for age, sex, country of origin (for IMMEnSE) or principal components (for the others) and disease stage (ISS). SNP associations were meta-analyzed.

RESULTS

SNP associations were meta-analyzed. From the meta-analysis, two MM risk SNPs were associated with OS (p<0.05), specifically POT1-AS1-rs2170352 (HR=1.37, 95% C.I.=1.09-1.73, p=0.007) and TNFRSF13B-rs4273077 (HR=1.19, 95% C.I.=1.01-1.41, p=0.04). The association between the combined 24 SNP MM-PRS and OS, however, was not significant.

CONCLUSIONS

Overall, our results did not support an association between the majority of MM risk SNPs and OS.

IMPACT

This is the first study to investigate the association between MM PRS and OS in MM.

Lenalidomide, bortezomib, and dexamethasone (RVd) ± autologous stem cell transplantation (ASCT) and R maintenance to progression for newly diagnosed multiple myeloma (NDMM): The phase 3 DETERMINATION trial

LBA4

Background: Optimal use of triplet/quadruplet induction, ASCT, and R-based maintenance in patients (pts) with NDMM who are eligible for transplant continues to evolve. The IFM 2009 trial, which used R maintenance for 1 year (y), showed progression-free survival (PFS; median, 35.0 vs. 47.3 months [mos]) but no overall survival benefit (OS; 60 vs. 62% at 8 y; median follow-up, 89.8 mos) with RVd + ASCT vs. RVd alone in the setting of multiple effective options at relapse, including ASCT at first relapse in 77% of pts (Attal M et al, N Engl J Med 2017; Perrot A et al, ASH 2020). We report primary data from our US DETERMINATION trial, which used R maintenance until progression. Methods: Pts with NDMM aged 18-65 y were randomly assigned to receive 3 RVd cycles, stem cell mobilization, and then 5 more RVd cycles (Arm A) or IV melphalan 200 mg/m2 + ASCT and 2 RVd cycles (Arm B). Each 21-d RVd cycle comprised PO R 25 mg (d 1-14), IV/SC bortezomib 1.3 mg/m2 (d 1, 4, 8, 11), and PO dexamethasone 20/10 mg (cycles 1-3/≥ 4; d 1, 2, 4, 5, 8, 9, 11, 12). Both arms received R 10-15 mg/d maintenance until progression or intolerance. The primary endpoint was PFS (90% power to detect PFS hazard ratio [HR] of 1.43 [Arm A vs. B] with α = 0.05 on stratified two-sided log-rank test; full information: 329 events in 720 pts). Data cut-off was Dec 10, 2021. Results: 357 and 365 pts were randomly assigned to Arms A and B, respectively; median age was 57 and 55 y, 14% and 13% had ISS stage III MM, and 18% each had high-risk cytogenetics [t(4;14), t(14;16), del17p]. In the respective arms, 291 and 290 pts received R maintenance for a median duration of 36 and 41 mos. After median follow-up of 76 mos and 328 events, median PFS was 46.2 vs. 67.6 mos in Arm A vs. B (HR 1.53; 95% CI, 1.23–1.91; p < .0001). Best responses in pts assessed to date were 52 vs. 62% ≥ CR (p = .006), 79 vs. 83% ≥ VGPR and 94 vs. 96% ≥ PR; in 251 evaluable pts, rate of MRD negativity (10-5) was 37.3 vs. 52.1% (p = .021) within 1 y of maintenance. 63 vs. 53% of pts have received subsequent treatment; of Arm A, 22% had ASCT as first non-protocol therapy. With 90 vs. 88 pts having died in Arm A vs. B, 4-y OS was 84% (95% CI, 80–88%) vs. 85% (95% CI, 81–88%); HR 1.10 (95% CI, 0.81–1.47; p = .274). Grade ≥ 3 related adverse events were less common in Arm A vs. B (78 vs. 94%; hematologic: 61 vs. 90%, p < .0001); 10 vs. 11% had secondary malignancies (ALL, 7 vs. 3 pts, p = .22; AML/MDS, 0 vs. 10 pts, p = .002). Difference in mean change from baseline in EORTC QLQ-C30 global health status score was < 10 points throughout treatment except at RVd cycle 5 vs. post-ASCT (compliance rate, 75% vs. 55%; mean change +3.0 vs. –11.1; p < .0001). Whole-genome sequencing, additional QOL, and correlative analyses are ongoing. Conclusions: RVd ± ASCT and R maintenance to progression resulted in the longest median PFS reported for each approach, and a highly significant 21.4-mo gain in median PFS benefit using RVd + ASCT. No OS advantage has been observed to date. Clinical trial information: NCT01208662.

Retrospective, single-center, real-world experience of belantamab mafodotin in relapsed/refractory multiple myeloma

8060

Background: Belantamab mafodotin (belamaf) is a BCMA antibody drug conjugate approved for the treatment of relapsed refractory multiple myeloma (RRMM) patients (pts) based on the pivotal phase 2 DREAMM-2 study (Lonial et al, Lancet Oncology, 2019), which demonstrated an overall response rate (ORR) of 32%, median progression free survival (PFS) of 2.8 months, and overall survival (OS) of 13.7 months in triple class (proteasome inhibitor, IMiD, and anti-CD38) refractory (TCR) MM. In this single-center retrospective study, we report the efficacy and safety of belamaf in RRMM pts administered in a real-world, standard of care (SOC) setting. Methods: All MM pts who initiated therapy with SOC belamaf, either as monotherapy or in combination, between 11/1/2020 and 11/30/2021 at MD Anderson were included in this study. Response and progression were evaluated using International Myeloma Working Group standard criteria. Keratopathy and best corrected visual acuity (BCVA) adverse events (AEs) were graded per the Keratopathy and Visual Acuity (KVA) scale. The Kaplan-Meier method was used to estimate time to event endpoints. Results: A total of 39 consecutive pts with a median of 7 prior lines of therapy were included in the analysis, of whom 37 pts (95%) received single agent belamaf. Median age was 66 years (range 39-89), 14 of 37 (38%) pts with available FISH had high risk disease (del 17p, t(4;14, and/or t(14;16)), 14 pts (36%) had extramedullary disease, 37 (95%) pts were TCR, 32 (82%) pts were TCR and alkylator-refractory, and 8 pts (21%) were BCMA-refractory. Notably, the majority (69%) of pts in this analysis would have been ineligible for the DREAMM-2 trial based on key eligibility criteria. Median number of belamaf doses administered was 2 (range 1-9). Among 37 pts with measurable, response evaluable baseline disease, the best ORR (≥ PR) was 27% with ≥ VGPR of 3%. The clinical benefit rate (≥ MR) was 35%. Among 8 BCMA-refractory pts, there was 1 PR and 1 MR. Median PFS was 1.8 months and median OS was 9.2 months with a median follow-up of 10.1 months. Median duration of response has not been reached among 10 responding pts. Among 33 pts with a post-treatment ocular exam, 25 pts (76%) developed any grade keratopathy (Grade 1/2/3/4, 9%/55%/12%/0%, respectively) and BCVA changes (Grade 1/2/3/4, 42%/27%/6%/0%, respectively). Median time to first keratopathy or BCVA AE was 1.3 months. The most common reasons for treatment discontinuation were disease progression (75%) and AEs (9%). Conclusions: Our current study in heavily pretreated RRMM pts, of whom the majority would have been ineligible for the DREAMM-2 study, demonstrates an ORR, PFS, and ocular AE profile with SOC belamaf therapy comparable to outcomes reported in the pivotal registration study. Future studies are needed to further define the optimal use and sequencing of belamaf in MM pts, particularly in context of other BCMA-targeting modalities.

Lenalidomide: Based maintenance after autologous hematopoietic stem cell transplant for patients with high-risk multiple myeloma

e20024

Background: Maintenance therapy with single-agent lenalidomide (Len) after autologous hematopoietic stem cell transplantation (autoHCT) for multiple myeloma (MM) is associated with improved progression-free survival (PFS). However, patients with high-risk chromosomal abnormalities may need a more intense regimen. We hypothesized that adding another anti-myeloma drug to Len would lead to improved outcomes. Methods: We conducted a retrospective single-center chart review of adult MM patients with high risk cytogenetic abnormalities that received autoHCT between 2008-2018, followed by Len-based maintenance therapy. High risk cytogenetics were defined as del17p, t(4;14), t(14;16), 1q21 gain or amplification by fluorescence in situ hybridization. We divided patients into those who received either single-agent Len maintenance (Len-only) or Len-based combinations (Len-combo). We compared PFS, overall survival (OS), non-relapse mortality (NRM), day 100 and best post-transplant responses, and minimal residual disease (MRD) status between groups. We performed sensitivity analyses using inverse probability weights to correct for potential bias due to nonrandomization of the two groups. Results: A total of 231 patients with HRMM were included in our analysis, with a median age of 62.4 (range 33.5-79.9) years, and 55% were male. There were 153 patients in the Len-only group and 78 in the Len-combo group. Len-combo regimens were either doublets (Len with dexamethasone [dex: n = 10], elotuzumab [n = 28] or ixazomib [n = 14]) or triplets (Len with bortezomib/dex [n = 10], ixazomib/dex [n = 10] or carfilzomib/dex [n = 6]). More patients in the Len-combo group had >2 high risk cytogenetic abnormalities compared to the Len-only group (32% vs. 12%: p < 0.001). Busulfan + melphalan (Bu-Mel) conditioning was used in 12% vs. 18% in Len-only vs. Len-combo groups (p = 0.32). The final best response post-transplant of sCR/CR was 50% in the Len-only group vs. 54% in the Len-combo group (p = 0.72). Median follow up was 40.7 and 35.3 months, with Len-only and Len-combo, respectively. Median PFS and OS for all patients were 25.5 and 82.6 months, respectively. There was no significant difference in PFS (HR: 1.01, CI: 0.71-1.44, p = 0.94) or OS (HR: 0.84, CI: 0.49-1.43, p = 0.52) between groups. Similarly, there was no difference in outcomes between the groups whether they received conditioning with melphalan-only or Bu-Mel. However, for patients with HR cytogenetic abnormalities other than 1q+ there was a trend towards better PFS with Len-combo (HR 0.59, CI 0.32-1.09, p = 0.09), without a difference in OS (HR: 0.79, CI: 0.37-1.65, p = 0.53). Conclusions: In this single center retrospective analysis, intensification of post-transplant Len maintenance did not show an improvement in outcomes for HRMM patients. However, there was a trend towards improved PFS in patients with HR abnormalities other than 1q+.

Phase II study of umbilical cord blood–derived natural killer (CB-NK) cells with elotuzumab, lenalidomide, and high-dose melphalan followed by autologous stem cell transplantation (ASCT) for patients with high-risk multiple myeloma (HRMM)

8009

Background: Despite the introduction of several novel agents over the past decade, patients with HRMM continue to have relatively poor outcomes. In a first-in-human study, we previously showed the feasibility of using CB-NK cells up to a dose of 1 x 108 cells/kg in MM patients undergoing high-dose melphalan (200 mg/m2; Mel200) plus lenalidomide and ASCT (NCT01729091). Lenalidomide enhances NK cell function and antibody-mediated cell toxicity against tumor targets. Our preclinical data showed that ex vivo expanded NK cells demonstrated higher elotuzumab-mediated cytotoxicity against myeloma targets than non-expanded cells, and the addition of elotuzumab to lenalidomide augmented the CB-NK cell ADCC against MM1.S myeloma targets. Hence, we aimed from this expansion part of the phase 2 clinical trial to determine the efficacy of CB-NK cells combined with elotuzumab/lenalidomide for HRMM undergoing ASCT. Methods: Patients with HRMM, ages 18-75 years, were eligible. HRMM defined as: disease relapse within 18 months of ASCT; fluorescence in situ hybridization (FISH) showing t(4:14), t(14:16), t(14:20), deletion (del) 17/17p or gain (amp) 1q; del(13) by conventional cytogenetic analysis; high-risk signatures as determined by the GEP-70 or EMC-92 gene expression profiles. With day 0 defined as day of stem cell infusion, treatment consisted of IV elotuzumab 10 mg/kg (days -15 and -8), oral lenalidomide 10 mg (days -8 to -2 prior to ASCT), Mel200 on day -7, and CB-NK cells on day -5. The primary endpoints were best response rate (≥VGPR) and minimal residual disease (MRD) at 3 months after ASCT, as defined per the IMWG criteria. MRD was tested by using 8-color multiparametric flow cytometry validated to a sensitivity level of 0.001% (1 cell in 100,000). Results: Thirty patients, with a median age of 63 (range, 40-72) years, were enrolled between 03/2018 and 01/2021. 97% had R-ISS stages 2/3, 40% had ≥2 high-risk genetic abnormalities, and 23% had del TP53. Most (80%) received induction therapy with bortezomib or carfilzomib + lenalidomide + dexamethasone, 1 patient had prior ASCT, and 4 received >1 prior line of therapy. Before ASCT, 73% had VGPR or better (40% in CR/sCR) and 40% had negative MRD. At 3 months after transplant, 97% achieved ≥VGPR (76%, CR/sCR) and 75% had negative MRD. At median follow-up of 26 (range, 12-44) months, only 4 patients progressed (3 had positive MRD after ASCT). The 2-year PFS and OS rates were 83% and 97%, respectively. No unexpected serious adverse effects attributable to NK cells were noted. Conclusions: CB-derived expanded NK cells plus elotuzumab/lenalidomide combined with Mel200 and ASCT results in excellent and durable hematologic and MRD responses in HRMM patients. Furthermore, PFS and OS rates compare favorably to published outcomes for HRMM patients. Clinical trial information: NCT01729091.

TTI-622-01: A phase 1a/1b dose-escalation and expansion trial of TTI-622 in patients with advanced hematologic malignancies, including multiple myeloma

TPS8071

Background: CD47 is an innate immune checkpoint that binds signal regulatory protein alpha (SIRPα) and delivers a "don’t eat me" signal to suppress macrophage phagocytosis. TTI-622 is a fusion protein consisting of the CD47-binding domain of human SIRPα linked to the Fc region of human IgG4. It is designed to enhance phagocytosis and antitumor activity by preventing CD47 from delivering its inhibitory signal as well as generating a moderate pro-phagocytic signal via IgG4 Fc. CD47 is significantly increased in multiple myeloma (MM) bone marrow mononuclear cells and expression inversely correlates with survival in patients. Relapsed/Refractory (R/R) MM shows particularly high expression of CD47. Preclinical studies demonstrate that the addition of proteasome inhibitors to CD47 blockade significantly increases phagocytosis of MM cells in vitro and anti-myeloma activity in vivo. The ongoing phase 1a part of this study has been previously described. The phase 1b part of the study will determine the safety and efficacy of TTI-622 when given as monotherapy or in combination with selected approved anticancer treatments in patients with hematological malignancies where new treatments with novel mechanism of action are needed. Here we describe 5 RRMM cohorts within phase 1b of the study. Methods: TTI-622-01 is a multi-center Phase 1a/1b study. Phase 1a was designed to determine the MTD, pharmacokinetics (PK), pharmacodynamics, and preliminary antitumor activity of QW, Q2W, and Q3W single-agent TTI-622 in R/R lymphoma using a 3+3 dose escalation schema. Phase 1b, ongoing, will determine the safety and recommended dose of TTI-622 to be given as single agent and in combination with carfilzomib + dexamethasone (Kd) in RRMM and will evaluate the preliminary efficacy. Secondary objectives are to further characterize the safety, PK and immunogenicity of TTI-622 when combined with Kd. Patients will be enrolled in 5 separate cohorts: 3 cohorts will explore different doses and administration schedules of TTI-622 combined with the approved dose of Kd; 2 cohorts will explore different doses of TTI-622 monotherapy. Cohorts will be opened in a staggered manner. In each cohort 3 patients will be dosed and followed for 28 days (21 days in the monotherapy) before expanding enrolment to approximately an additional 27 patients. Key eligibility criteria include: relapse or progression following ≥3 prior lines of therapy (including a proteasome inhibitor, an immunomodulatory drug, and an anti-CD38 antibody), carfilzomib-refractory progressive and measurable disease per IMWG at study entry; age ≥18 years; ECOG performance status ≤2; adequate organ functions; no known CNS involvement; no prior anti-CD47 or anti-SIRPα therapy. Patient recruitment is planned or ongoing at 40 sites worldwide. Clinical trial information: NCT03530683.

Daratumumab (DARA) + lenalidomide, bortezomib, and dexamethasone (RVd) in transplant-eligible newly diagnosed multiple myeloma (NDMM): A post hoc analysis of sustained minimal residual disease (MRD) negativity from GRIFFIN

8011

Background: In the primary analysis of the phase 2 randomized GRIFFIN study, DARA + RVd (D-RVd) improved the stringent complete response (sCR) rate by end of consolidation for transplant-eligible NDMM (42.4% vs 32.0%; 1-sided P = 0.068). With longer follow-up (median, 38.6 mo), D-RVd vs RVd improved MRD-negativity (10–5) rates in clinically relevant subgroups (ISS stage III, 71% vs 36%; high cytogenetic risk, 44% vs 29% [del17p, t(4;14), or t(14;16)]; revised high cytogenetic risk, 55% vs 32% [del17p, t(4;14), t(14;16), t(14;20), or gain 1q]). Here we present a post hoc analysis of sustained MRD negativity (median follow-up, 38.6 mo) in the same subgroups and in patients (pts) with ≥CR. Methods: Transplant-eligible NDMM pts were randomized 1:1 to 4 D-RVd/RVd induction cycles, ASCT, 2 D-RVd/RVd consolidation cycles, and 2 years of maintenance therapy with lenalidomide (R) ± DARA. For induction/consolidation (21-day cycles), pts received R (25 mg PO Days [D] 1-14), V (1.3 mg/m2 SC D1, 4, 8, 11), and d (40 mg PO weekly) ± DARA (16 mg/kg IV D1, 8, 15 of Cycles 1-4 and D1 of Cycles 5-6). In maintenance (28-day cycles), pts received R (10 mg PO D1-21; if tolerated, 15 mg in Cycles 10+) ± DARA (16 mg/kg IV Q8W/Q4W or 1800 mg SC per protocol amendments). The primary endpoint was sCR rate by end of consolidation. Results: The following features were balanced among randomized pts (D-RVd, n = 104; RVd, n = 103): high cytogenetic risk (16; 14), revised high cytogenetic risk (42; 37), gain 1q (34; 28), and ISS stage III (14; 14). Sustained MRD-negativity rates at 10–5 lasting ≥6 and ≥12 months were higher for D-RVd vs RVd among all high-risk subgroups (Table). D-RVd was superior to RVd for rates of sustained MRD negativity lasting ≥12 months for pts with ≥CR (53.7% vs 20.3%) and sCR (59.1% vs 17.4%; Table). Among all pts with sustained MRD negativity, only 1 D-RVd pt subsequently had disease progression, and 1 RVd pt died. Additional data on MRD at 10–6 and PFS will be presented. Conclusions: MRD data in GRIFFIN show that the addition of DARA to RVd induction/consolidation and R maintenance may lead to durable MRD-negativity (10–5) rates in pts with transplant-eligible NDMM with high cytogenetic risk, ISS stage III, and those who achieve ≥CR or sCR, however larger studies are needed. Clinical trial information: NCT02874742. [Table: see text]

Randomized phase II trial of bortezomib, lenalidomide, dexamthasone with/without elotuzumab for newly diagnosed, high risk multiple myeloma (SWOG-1211)

8054

Background: The introduction of immunomodulatory agents, proteasome inhibitors, and autologous stem cell transplantation (ASCT) has improved outcomes for patients with multiple myeloma (MM), but those with high risk MM (HRMM) have a poor long-term prognosis. Herein we provide survival outcomes on the first randomized trial in newly diagnosed HRMM, S1211, to follow-up on the previously reported progression-free survival (PFS) (NCT01668719, Usmani SZ et al, Lancet Haem 2021). Methods: S1211 is a randomized phase II trial comparing 8 cycles of lenalidomide, bortezomib and dexamethasone (RVd) induction followed by dose-attenuated RVd maintenance until disease progression with or without elotuzumab (RVd-Elo). Stem cell collection was allowed, but ASCT was deferred until progression. HRMM was defined by one of the following: gene expression profiling high-risk (GEPhi), t(14;16), t(14;20), del(17p), amplification 1q21, primary plasma cell leukemia (pPCL), or elevated serum LDH (> 2X ULN). Median PFS was the primary endpoint, using a one-sided stratified log-rank test at a one-sided significance level of 0.1. Secondary endpoints included overall response rate (ORR), adverse events (AE), serious adverse events (SAE) and OS. Response was assessed using the IMWG 2009 criteria. Results: S1211 enrolled 103 evaluable patients, RVd n=54, RVd-Elo n=49. 74% had ISS II/III, 48% amp1q21, 38% del(17p), 11% t(14;16), 9% GEPhi, 7% pPCL, 5% t(14;20) and 4% elevated LDH (17% >1 feature). With median follow-up of 72 months (mos.), no difference in median PFS was observed [RVd-Elo=29 mos., RVd= 34 mos., HR = 1.11 (80% CI=0.82, 1.49, p=0.66]. No difference in OS was observed [RVd-Elo = median not reached (NR), RVd= 68 mos., HR = 0.85 (80% CI: 0.59, 1.23), p-value = 0.58]. 76% pts had >Grade 3 AEs, no differences in the safety profile were observed. Amongst patients with gain/amp 1q21, median PFS was [RVd-Elo=31 mos., RVd= 37 mos., HR = 1.48 (80% CI= 0.95, 2.31), p=0.25], median OS was [RVd-Elo = 61 mos., RVd= 68 mos., HR = 1.23 (80% CI: 0.72, 2.10), p-value = 0.63]. In patients with del(17p), median PFS was RVd-Elo=41 mos., RVd= 30 mos.[HR = 0.98 (80% CI= 0.60, 1.58), p=0.95], median OS RVd-Elo = NR, RVd= 72 mos., [HR = 0.77 (80% CI: 0.40, 1.48), p-value = 0.61]. Conclusions: In the first randomized HRMM study reported to date, the addition of Elo to RVd induction and maintenance did not improve PFS and OS with a median follow-up of 6 years. Although the median PFS for Del17p subgroup on RVd-Elo arm is higher than RVd, it did not achieve statistical significance. The PFS and OS observed for gain/amp 1q21 and del17p in the RVd control arm may serve as important benchmarks for future enrichment design HRMM clinical trials. The PFS and OS in both arms of the study exceeded the original statistical assumptions and support the role for PI/IMiD combination induction/maintenance therapy for this population. Clinical trial information: NCT01668719.

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.

Expression of histone deacetylase (HDAC) family members in bortezomib-refractory multiple myeloma and modulation by panobinostat

AIM

Multiple myeloma (MM) is a hematological malignancy of antibody-producing mature B cells or plasma cells. The proteasome inhibitor, bortezomib, was the first-in-class compound to be FDA approved for MM and is frequently utilized in induction therapy. However, bortezomib refractory disease is a major clinical concern, and the efficacy of the pan-histone deacetylase inhibitor (HDACi), panobinostat, in bortezomib refractory disease indicates that HDAC targeting is a viable strategy. Here, we utilized isogenic bortezomib resistant models to profile HDAC expression and define baseline and HDACi-induced expression patterns of individual HDAC family members in sensitive vs. resistant cells to better understanding the potential for targeting these enzymes.

METHODS

Gene expression of HDAC family members in two sets of isogenic bortezomib sensitive or resistant myeloma cell lines was examined. These cell lines were subsequently treated with HDAC inhibitors: panobinostat or vorinostat, and HDAC expression was evaluated. CRISPR/Cas9 knockdown and pharmacological inhibition of specific HDAC family members were conducted.

RESULTS

Interestingly, HDAC6 and HDAC7 were significantly upregulated and downregulated, respectively, in bortezomib-resistant cells. Panobinostat was effective at inducing cell death in these lines and modulated HDAC expression in cell lines and patient samples. Knockdown of HDAC7 inhibited cell growth while pharmacologically inhibiting HDAC6 augmented cell death by panobinostat.

CONCLUSION

Our data revealed heterogeneous expression of individual HDACs in bortezomib sensitive vs. resistant isogenic cell lines and patient samples treated with panobinostat. Cumulatively our findings highlight distinct roles for HDAC6 and HDAC7 in regulating cell death in the context of bortezomib resistance.