Real world data on outcomes of anti-CD38 antibody treated, including triple class refractory, patients with multiple myeloma: a multi-institutional report from the Canadian Myeloma Research Group (CMRG) Database

Multiple myeloma (MM) remains incurable despite the availability of novel agents. This multi-center retrospective cohort study used the Canadian Myeloma Research Group Database to describe real-world outcomes of patients withanti-CD38 monoclonal antibody (mAb) refractory MM subsequently treated with standard of care (SoC) regimens. Patients with triple class refractory (TCR) disease (refractory to a proteasome inhibitor, immunomodulatory drug, and anti-CD38 mAb) were examined as a distinct cohort. Overall, 663 patients had disease progression on anti-CD38 mAb therapy, 466 received further treatment (346 with SoC regimens were included, 120 with investigational agents on clinical trial and were excluded). The median age at initiation of subsequent SoC therapy of 67.9 (range 39.6-89.6) years with a median of 3 prior lines (range 1-9). The median PFS and OS from the start of subsequent therapy was 4.6 (95% CI 4.1-5.6) months and 13.3 (95% CI 10.6-16.6) months, respectively. The median PFS and OS of patients with TCR disease (n = 199) was 4.4 (95% CI 3.6-5.3) months and 10.5 (95% CI 8.5-13.8) months. Our results reinforce that real-world patients with relapsed MM, particularly those with TCR disease, have dismal outcomes. There remains an urgent unmet need for the development of and access to effective therapeutics for these patients.

Cancer-specific mortality in multiple myeloma: a population-based retrospective cohort study

Survival has improved in patients diagnosed with multiple myeloma (MM) over the last two decades; however, there remains a paucity of data on the causes of death in MM patients and whether causes of death change during the disease trajectory. We conducted a retrospective population-based study to evaluate the rates of MM-specific versus non-MM cause of death and to identify factors associated with cause-specific death in MM patients, stratified into autologous stem cell transplant (ASCT) and non-ASCT cohorts. A total of 6,677 patients were included, 2,576 in the ASCT group and 4,010 in the non-ASCT group. Eight hundred and seventy-three (34%) ASCT patients and 2,787 (68%) non-ASCT patients died during the follow-up period. MM was the most frequent causes of death, causing 74% of deaths in the ASCT group and 67% in the non-ASCT group. Other cancers were the second leading causes of death, followed by cardiac and infectious diseases. Multivariable analysis demonstrated that a more recent year of diagnosis and novel agent use within 1 year of diagnosis were associated with a decreased risk of MM-specific death, whereas a history of previous non-MM cancer, older age, and the presence of CRAB criteria at diagnosis increased the risk of non-MM death. Our data suggests that despite improvement in MM outcomes in recent years, MM remains the greatest threat to overall survival for patients. Further advances in the development of effective MM therapeutic agents in both ASCT and non-ASCT populations and patient access to them is needed to improve outcomes.

Outcome of carfilzomib/pomalidomide-based regimens after daratumumab-based treatment in relapsed multiple myeloma: A Canadian Myeloma Research Group Database analysis

INTRODUCTION

Although daratumumab-containing regimens improve multiple myeloma (MM) outcomes, recurrence is inevitable.

METHODS AND OBJECTIVE

We performed a retrospective study using the Canadian Myeloma Research Group Database to benchmark the efficacy of carfilzomib- or pomalidomide-based therapies immediately following progression on daratumumab treatment.

RESULTS

We identified 178 such patients; median number of prior lines of therapy was 3, 97% triple-class exposed, and 60% triple-class refractory. In our cohort, 75 received a subsequent carfilzomib-based therapy, 79 received a pomalidomide-based therapy, and 24 received a treatment with both immunomodulatory drug (IMiD) and proteasome inhibitor (PI) using carfilzomib and/or pomalidomide. The median progression-free survival (PFS) and overall survival (OS) for the entire cohort were 4.5 and 14.2 months, respectively. Carfilzomib-based therapy yielded a median PFS and OS of 4.5 and 10.2 months, respectively, compared to 5.2 and 21.7 months for pomalidomide-based therapy. Patients who received both IMiD and PI with carfilzomib and/or pomalidomide had a median PFS and OS of 4.1 and 14.5 months, respectively.

CONCLUSION

Our observations demonstrate the poor outcome of MM patients when standard regimens based on carfilzomib and/or pomalidomide are utilized directly after daratumumab-based therapy given in the relapsed setting. Novel therapies, including immune therapies, are urgently needed to improve the outcomes of these daratumumab-exposed patients.

Canadian real-world experience of asciminib treatment in heavily pre-treated chronic myeloid leukemia (CML) patients who failed multiple lines of tyrosine kinase inhibitor (TKI) therapy

BACKGROUND

Asciminib is a novel drug specifically targeting ABL myristoyl pocket in the ABL1 protein.

METHODS

Forty one patients with chronic myeloid leukemia treated with asciminib from 2018 to 2022 were reviewed and analyzed for the efficacy and tolerability of asciminib using real-world experience data.

RESULTS

The median age was 60 years (range 17-90) with a past history of a cardiovascular event in 21 patients (51%). Patients were pretreated with a median of 3 previous tyrosine kinase inhibitors (range 1-5). After a median of 12 months of asciminib (range 3-41), major molecular response (MMR) rate was 39% (n = 11/28) and 42% (n = 5/12) at 6 and 12 months, respectively. Molecular response with 2 log reduction (MR2) was noted in 54% (n = 15/28) and 50% (n = 6/12) at 6 and 12 months. The cumulative incidence of MMR and MR2 was 46.3% and 66% at 12 months. Five patients discontinued asciminib due to treatment failure (n = 3) or thrombocytopenia (n = 2). There were no cardiovascular events. Out of 7 patients treated with high dose asciminib for T315I mutation, 5 patients achieved MMR or deeper response. The event-free survival was 63% at 12 months.

CONCLUSION

This study confirmed clinical efficacy and tolerability of asciminib with real-world experience.

Real-world results of autologous stem cell transplantation in newly diagnosed multiple myeloma: a report from the Canadian Myeloma Research Group database

Autologous stem cell transplant (ASCT) remains an important option for eligible multiple myeloma (MM) patients as part of initial therapy. Using the Canadian Myeloma Research Group (CMRG) national database, we examined the details and outcomes of ASCT performed as first-line therapy in eligible Canadian MM patients between 2007 to 2021. We included 3821 patients with 72% receiving CyBorD induction and 2061 patients receiving maintenance, consisting of lenalidomide +/- steroids in 78.3%. The median PFS and OS for patients given a single ASCT were 35.4 and 126 months. Those receiving a second induction regimen had significantly inferior outcomes, although when maintenance was used, results were comparable regardless of the number of induction regimens administered (median PFS 55.3 vs 51.1 months [p = 0.11]; median OS 158.6 vs not yet reached [p = 0.13]). Consolidation patients had a longer median PFS (55.3 vs 34.4 months [p = 0.001]), but no significant gain in median OS (p = 0.065). Patients who received lenalidomide-based maintenance experienced a median PFS of 53.7 months and OS of 159 months. In the multivariable analysis, use of any type of maintenance therapy vs no maintenance was associated with a lower risk of progression (HR 0.52 (95% CI 0.47-0.57)) and death (HR 0.58 (95% CI 0.51-0.67)). This real-world study demonstrates that, overall, first-line treatment sequence in transplant-eligible patients produces a median OS of ≥10 years. It also highlights the contribution of post-ASCT maintenance, particularly lenalidomide given until progression.

Redefining attrition in multiple myeloma (MM): a Canadian Myeloma Research Group (CMRG) analysis

While most patients diagnosed with multiple myeloma (MM) receive initial therapy, reported attrition rates are high. Understanding attrition rates and characteristics of patients not receiving subsequent therapy is useful for MM stakeholders. We performed an analysis of attrition rates in a large disease-specific database of patients with newly diagnosed MM who received at least one line of therapy between Jan 1/10-Dec 31/20. Attrition was defined as failure to receive a subsequent line of therapy despite progression of MM or due to death. A total of 5548 patients were identified, 3111 autologous stem cell transplant (ASCT) patients and 2437 non-ASCT. In the ASCT cohort, the attrition rate was 7% after line 1, 12% after line 2, and 23% after line 3. In non-ASCT patients, the attrition rate was 19% after line 1, 26% after line 2, and 40% after line 3. Death was the dominant contributor to attrition across all cohorts, with a minority of patients alive with progressive disease in the absence of further therapy at each line. Multivariable analysis identified older age, shorter time to progression, and inferior response as independent risk factors for attrition. Our data show that attrition rates increase with each line of therapy and are higher in non-ASCT patients but are appreciably lower than previously reported. This study supports a revision of the previous definition of attrition, demonstrating that most patients who do not receive subsequent therapy are either continuing their current therapy and/or are in remission off-treatment rather than being irreversibly lost to attrition.

A Canadian Perspective on the Treatment of Waldenström Macroglobulinemia

Waldenström macroglobulinemia (WM) is a slowly progressing B-cell non-Hodgkin lymphoma characterized by monoclonal IgM gammopathy in the blood and infiltration of the bone marrow by clonal lymphoplasmacytic cells. As an incurable disease, the goals for therapy for WM are to relieve symptoms, slow disease progression, prevent organ damage, and maintain quality of life. However, given the rarity of WM, clinical trials comparing treatments for WM are limited and there is no definitive standard of care. The selection of first-line WM therapy is thus based on patient factors, disease characteristics, and drug access, with bendamustine-rituximab and Bruton's tyrosine kinase (BTK) inhibitor therapy considered preferred treatments. Other treatments such as proteasome inhibitor- or purine analogue-based therapy, alternative chemoimmunotherapy, and autologous stem cell transplantation are generally reserved for the relapsed setting but may be used in rare circumstances in earlier lines of therapy. This paper summarizes the efficacy and safety of these WM therapies and discusses considerations for treatment from a Canadian perspective.

Testing Mayo Clinic’s new 20/20/20 risk stratification model in another cohort of smoldering myeloma patients: A retrospective study

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Background: Smoldering multiple myeloma (SMM) is an asymptomatic plasma cell disorder associated with a high risk of transformation to symptomatic multiple myeloma (MM). SMM risk of progression to MM is highly heterogeneous and several models have been suggested to predict this risk, but none have yet been adopted internationally. Lakshman et al. recently proposed a risk stratification model based on three markers: bone marrow plasma cell (BMPC) percentage > 20%, free light chain ratio (FLCr) > 20 and serum M protein > 20 g/L. In this “20/20/20” model, patients with 0, 1 or ≥ 2 risk factors are respectively considered at low, intermediate and high-risk of progression. The goal of our study was to test this risk model in our population and to determine if similar results could be obtained in another cohort of SMM patients. Methods: We conducted a retrospective, single center study with 89 patients diagnosed with SMM between January 2008 and December 2019. Patients were identified by query of the electronic medical records and the 2014 International Myeloma Working Group (IMWG) diagnostic criteria for SMM were used to determine eligibility. The main endpoint was progression to symptomatic multiple myeloma or amyloidosis. Results: All three markers proposed by Lakshman et al. were associated with an increased risk of progression: BMPC percentage ≥ 20% (hazard ratio [HR]: 4.28 [95% C.I., 1.90 – 9.61]; p < 0.001), serum M protein ≥ 20g/L (HR: 4.20 [95% C.I., 1.90 – 15.53]; p = 0.032) and FLCr ≥ 20 (HR: 3.25 [95% C.I., 1.09 – 9.71]; p = 0.035). Immunoparesis (HR: 2.61 [95% C.I., 1.07 – 6.41]; p = 0.036) was also an independent risk factor in our population. The estimated median time to progression (TTP) was not reached for the low and intermediate risk groups and was 29.1 months (95% C.I., 3.9 – 54.4) in the high-risk group (p = 0.006). The estimated mean TTP for the low-risk group, the intermediate-risk group and the high-risk group were respectively 78.4 months (95% C.I., 68.3 – 88.5), 48.3 months (95% C.I., 31.9 – 64.8) and 35.2 months (95% C.I., 19.1 – 51.2). Sex, IgA isotype, positive Bence-Jones, abnormal β2-microglobulin and MGUS prior to SMM did not result in an increased risk of progression. The estimated proportion of progression-free patients at 1, 2 and 5 years were 96.8%, 93.4% and 77.5% for the low-risk group, 80.0%, 80.0% and 62.2% for the intermediate risk group and 70.0%, 58.3% and 29.2% for the high-risk group. Conclusions: When Mayo Clinic’s new 20/20/20 risk model was applied to our population, it adequately predicted the risk of progression to symptomatic disease at 2 years. As it relies on readily available biological parameters, this model is easy to use and can be applied in most clinical settings. We believe this model could be used to further study therapeutic approaches in higher risk SMM.

Canadian perspective on managing multiple myeloma during the COVID-19 pandemic: lessons learned and future considerations

The coronavirus disease 2019 (covid-19) pandemic caused by the novel severe acute respiratory syndrome coronavirus 2 has necessitated changes to the way patients with chronic diseases are managed. Given that patients with multiple myeloma are at increased risk of covid-19 infection and related complications, national bodies and experts around the globe have made recommendations for risk mitigation strategies for those vulnerable patients. Understandably, because of the novelty of the virus, many of the proposed risk mitigation strategies have thus far been reactionary and cannot be supported by strong evidence. In this editorial, we highlight some of the risk mitigation strategies implemented at our institutions across Canada during the first wave of covid-19, and we discuss the considerations that should be made when managing patients during the second wave and beyond.

Circulating tumour DNA sequence analysis as an alternative to multiple myeloma bone marrow aspirates

The requirement for bone-marrow aspirates for genomic profiling of multiple myeloma poses an obstacle to enrolment and retention of patients in clinical trials. We evaluated whether circulating cell-free DNA (cfDNA) analysis is comparable to molecular profiling of myeloma using bone-marrow tumour cells. We report here a hybrid-capture-based Liquid Biopsy Sequencing (LB-Seq) method used to sequence all protein-coding exons of KRAS, NRAS, BRAF, EGFR and PIK3CA in 64 cfDNA specimens from 53 myeloma patients to >20,000 × median coverage. This method includes a variant filtering algorithm that enables detection of tumour-derived fragments present in cfDNA at allele frequencies as low as 0.25% (median 3.2%, range 0.25–46%). Using LB-Seq analysis of 48 cfDNA specimens with matched bone-marrow data, we detect 49/51 likely somatic mutations, with subclonal hierarchies reflecting tumour profiling (96% concordance), and four additional mutations likely missed by bone-marrow testing (>98% specificity). Overall, LB-Seq is a high fidelity adjunct to genetic profiling of bone-marrow in multiple myeloma.

Genetic profiling of multiple myeloma requires painful bone marrow biopsies. Here, the authors develop an alternative non-invasive method for sequencing of five oncogenes in circulating cell-free DNA from myeloma patients, demonstrating 96% concordance with bone marrow tumour profiling results.

Abstract 615: Noninvasive diagnosis of actionable mutations by deep sequencing of circulating tumor DNA in multiple myeloma

Background: Genome sequencing of multiple myeloma (MM) tumors has revealed recurrent mutations that serve as a fertile ground for targeted therapies. Indeed, activating mutations of KRAS, NRAS and BRAF have been reported in approximately 27%, 24% and 4% of MM cases. Based on this observation, we initiated a Phase II NCI-CTEP sponsored clinical trial of trametinib in patients with MM (PHL-9460). Detection of mutations currently require bone marrow aspirates that are invasive and can yield suboptimal samples. Targeted, ultra-deep sequencing of circulating tumor DNA (ctDNA) is a promising tool for accessing the tumor genome that has not been well studied in MM. We set out to determine the feasibility of detecting ctDNA in MM and of identifying actionable mutations and mutational load using liquid biopsy through ctDNA analysis.

Methods: MM patients enrolled onto PHL-9460 or those with heavy tumor burden were identified and consented to have their peripheral blood drawn for analysis. Where possible, matched tumor DNA was also obtained. Cell-free DNA was extracted from 7-15 mL of plasma isolated within ¬1 hour of blood draw using the QIAamp Circulating Nucleic Acid Kit and tagged with barcoded sequencing adapters for subsequent pooling. All exons of KRAS, NRAS, BRAF, PIK3CA and EGFR genes were isolated using a custom hybrid capture panel (IDT xGen Lockdown) and sequenced on an Illumina HiSeq 2000. Reads were aligned to the human genome reference (hg19) using bwa and somatic mutations were detected using muTect.

Results: We have collected 25 samples from 23 patients, 7 from patients on PHL-9460, 5 newly diagnosed, and 13 from relapsed patients having received 3.3 median prior lines of therapy (range 1-7). To date, 11 samples from 10 patients have been sequenced. The sample with the lowest DNA yield failed due to low library complexity (range 16.6-3872 ng, median yield: 197 ng). From the remaining 10 samples, the mean target coverage ranged from 31,500 to 32,500. Somatic mutations in KRAS, NRAS, or PIK3CA genes were present in 5 of 9 patients with mutant allele frequencies ranging from 1.1% to 32% (3 KRAS and 2 NRAS of which 2 cases also had a low frequency PIK3CA mutation). We did not uncover mutations in BRAF or EGFR. For patients with matched tumor DNA, mutations in ctDNA concurred with those found in tumor DNA sequencing (4 of 4 tumors with known genotypes). Two patients with NRAS mutations enrolled onto PHL-9460 have responded to trametinib (1 partial and 1 minor response) and remain on therapy.

Conclusion: ctDNA analysis in this cohort has identified key mutations in MM. The rate of RAS or RAF mutations in ctDNA compared to matched tumors and correlation to response to trametinib is ongoing and will be presented. Preliminary data suggest that ctDNA may be a reliable method of detecting mutations in MM and an alternative to bone marrow biopsy.

Citation Format: Rayan Kaedbey, Olena Kis, Arnavaz Danesh, Mark Dowar, Tiantian Li, Zhihua Li, Jessica Liu, Mark Mansour, Mahadeo Sukhai, Tong Zhang, Suzanne Kamel-Reid, Trevor J. Pugh, Suzanne Trudel. Noninvasive diagnosis of actionable mutations by deep sequencing of circulating tumor DNA in multiple myeloma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 615. doi:10.1158/1538-7445.AM2015-615