Upfront autologous haematopoietic stem-cell transplantation versus carfilzomib-cyclophosphamide-dexamethasone consolidation with carfilzomib maintenance in patients with newly diagnosed multiple myeloma in England and Wales (CARDAMON): a randomised, phase 2, non-inferiority trial

BACKGROUND

Standard-of-care treatment for patients with newly diagnosed multiple myeloma is bortezomib-based induction followed by high-dose melphalan and autologous haematopoietic stem-cell transplantation (HSCT) and lenalidomide maintenance. We aimed to evaluate whether an immunomodulatory-free carfilzomib-based induction, consolidation, and maintenance protocol without autologous HSCT was non-inferior to the same induction regimen followed by autologous HSCT and maintenance.

METHODS

CARDAMON is a randomised, open-label, phase 2 trial in 19 hospitals in England and Wales, UK. Newly diagnosed, transplantation-eligible patients with multiple myeloma aged 18 years or older with an Eastern Cooperative Oncology Group (ECOG) performance status of 0-2 received four 28-day cycles of carfilzomib (56 mg/m² intravenously on days 1, 2, 8, 9, 15, and 16), cyclophosphamide (500 mg orally on days 1, 8, and 15), and dexamethasone (40 mg orally on days 1, 8, 15, and 22; KCd), followed by peripheral blood stem cell mobilisation. Patients with at least a partial response were randomly assigned (1:1) to either high-dose melphalan and autologous HSCT or four cycles of KCd. All randomised patients received 18 cycles of carfilzomib maintenance (56 mg/m² intravenously on days 1, 8, and 15). The primary outcomes were the proportion of patients with at least a very good partial response after induction and difference in progression-free survival rate at 2 years from randomisation (non-inferiority margin 10%), both assessed by intention to treat. Safety was assessed in all patients who started treatment. The trial is registered with ClinicalTrials.gov (NCT02315716); recruitment is complete and all patients are in follow-up.

FINDINGS

Between June 16, 2015, and July 8, 2019, 281 patients were enrolled, with 218 proceeding to randomisation (109 assigned to the KCd consolidation group [99 of whom completed consolidation] and 109 to the HSCT group [104 of whom underwent transplantation]). A further seven patients withdrew before initiation of carfilzomib maintenance (two in the KCd consolidation group vs five in the HSCT group). Median age was 59 years (IQR 52 to 64); 166 (59%) of 281 patients were male and 115 (41%) were female. 152 (71%) of 214 patients with known ethnicity were White, 37 (17%) were Black, 18 (8%) were Asian, 5 (2%) identified as Mixed, and 2 (1%) identified as other. Median follow-up from randomisation was 40·2 months (IQR 32·7 to 51·8). After induction, 162 (57·7%; 95% CI 51·6 to 63·5) of 281 patients had at least a very good partial response. The 2-year progression-free survival was 75% (95% CI 65 to 82) in the HSCT group versus 68% (95% CI 58 to 76) in the KCd group (difference -7·2%, 70% CI -11·1 to -2·8), exceeding the non-inferiority margin. The most common grade 3-4 events during KCd induction and consolidation were lymphocytopenia (72 [26%] of 278 patients who started induction; 15 [14%] of 109 patients who started consolidation) and infection (50 [18%] of 278 for induction; 15 [14%] of 109 for consolidation), and during carfilzomib maintenance were hypertension (20 [21%] of 97 patients in the KCd consolidation group vs 23 [23%] of 99 patients in the HSCT group) and infection (16 [16%] of 97 patients vs 25 [25%] of 99). Treatment-related serious adverse events at any point during the trial were reported in 109 (39%) of 278 patients who started induction, with infections (80 [29%]) being the most common. Treatment-emergent deaths were reported in five (2%) of 278 patients during induction (three from infection, one from cardiac event, and one from renal failure) and one of 99 patients during maintenance after autologous HSCT (oesophageal carcinoma).

INTERPRETATION

KCd did not meet the criteria for non-inferiority compared with autologous HSCT, but the marginal difference in progression-free survival suggests that further studies are warranted to explore deferred autologous HSCT in some subgroups, such as individuals who are MRD negative after induction.

FUNDING

Cancer Research UK and Amgen.

Minimal Residual Disease After Autologous Stem-Cell Transplant for Patients With Myeloma: Prognostic Significance and the Impact of Lenalidomide Maintenance and Molecular Risk

PURPOSE

Minimal residual disease (MRD) can predict outcomes in patients with multiple myeloma, but limited data are available on the prognostic impact of MRD when assessed at serial time points in the context of maintenance therapy after autologous stem-cell transplant (ASCT) and the interaction between MRD and molecular risk.

METHODS

Data from a large phase III trial (Myeloma XI) were examined to determine the relationship between MRD status, progression-free survival (PFS), and overall survival (OS) in post-ASCT patients randomly assigned to lenalidomide maintenance or no maintenance at 3 months after ASCT. MRD status was assessed by flow cytometry (median sensitivity 0.004%) before maintenance random assignment (ASCT + 3) and 6 months later (ASCT + 9).

RESULTS

At ASCT + 3, 475 of 750 (63.3%) patients were MRD-negative and 275 (36.7%) were MRD-positive. MRD-negative status was associated with improved PFS (hazard ratio [HR] = 0.47; 95% CI, 0.37 to 0.58 P < .001) and OS (HR = 0.59; 95% CI, 0.40 to 0.85; P = .0046). At ASCT + 9, 214 of 326 (65.6%) were MRD-negative and 112 (34.4%) were MRD-positive. MRD-negative status was associated with improved PFS (HR = 0.20; 95% CI, 0.13 to 0.31; P < .0001) and OS (HR = 0.33; 95% CI, 0.15 to 0.75; P = .0077). The findings were very similar when restricted to patients with complete response/near complete response. Sustained MRD negativity from ASCT + 3 to ASCT + 9 or the conversion to MRD negativity by ASCT + 9 was associated with the longest PFS/OS. Patients randomly assigned to lenalidomide maintenance were more likely to convert from being MRD-positive before maintenance random assignment to MRD-negative 6 months later (lenalidomide 30%, observation 17%). High-risk molecular features had an adverse effect on PFS and OS even for those patients achieving MRD-negative status. On multivariable analysis of MRD status, maintenance therapy and molecular risk maintained prognostic impact at both ASCT + 3 and ASCT + 9.

CONCLUSION

In patients with multiple myeloma, MRD status at both ASCT + 3 and ASCT + 9 is a powerful predictor of PFS and OS.

Carfilzomib, lenalidomide, dexamethasone, and cyclophosphamide (KRdc) as induction therapy for transplant-eligible, newly diagnosed multiple myeloma patients (Myeloma XI+): Interim analysis of an open-label randomised controlled trial

BACKGROUND

Carfilzomib is a second-generation irreversible proteasome inhibitor that is efficacious in the treatment of myeloma and carries less risk of peripheral neuropathy than first-generation proteasome inhibitors, making it more amenable to combination therapy.

METHODS AND FINDINGS

The Myeloma XI+ trial recruited patients from 88 sites across the UK between 5 December 2013 and 20 April 2016. Patients with newly diagnosed multiple myeloma eligible for transplantation were randomly assigned to receive the combination carfilzomib, lenalidomide, dexamethasone, and cyclophosphamide (KRdc) or a triplet of lenalidomide, dexamethasone, and cyclophosphamide (Rdc) or thalidomide, dexamethasone, and cyclophosphamide (Tdc). All patients were planned to receive an autologous stem cell transplantation (ASCT) prior to a randomisation between lenalidomide maintenance and observation. Eligible patients were aged over 18 years and had symptomatic myeloma. The co-primary endpoints for the study were progression-free survival (PFS) and overall survival (OS) for KRdc versus the Tdc/Rdc control group by intention to treat. PFS, response, and safety outcomes are reported following a planned interim analysis. The trial is registered (ISRCTN49407852) and has completed recruitment. In total, 1,056 patients (median age 61 years, range 33 to 75, 39.1% female) underwent induction randomisation to KRdc (n = 526) or control (Tdc/Rdc, n = 530). After a median follow-up of 34.5 months, KRdc was associated with a significantly longer PFS than the triplet control group (hazard ratio 0.63, 95% CI 0.51-0.76). The median PFS for patients receiving KRdc is not yet estimable, versus 36.2 months for the triplet control group (p < 0.001). Improved PFS was consistent across subgroups of patients including those with genetically high-risk disease. At the end of induction, the percentage of patients achieving at least a very good partial response was 82.3% in the KRdc group versus 58.9% in the control group (odds ratio 4.35, 95% CI 3.19-5.94, p < 0.001). Minimal residual disease negativity (cutoff 4 × 10-5 bone marrow leucocytes) was achieved in 55% of patients tested in the KRdc group at the end of induction, increasing to 75% of those tested after ASCT. The most common adverse events were haematological, with a low incidence of cardiac events. The trial continues to follow up patients to the co-primary endpoint of OS and for planned long-term follow-up analysis. Limitations of the study include a lack of blinding to treatment regimen and that the triplet control regimen did not include a proteasome inhibitor for all patients, which would be considered a current standard of care in many parts of the world.

CONCLUSIONS

The KRdc combination was well tolerated and was associated with both an increased percentage of patients achieving at least a very good partial response and a significant PFS benefit compared to immunomodulatory-agent-based triplet therapy.

TRIAL REGISTRATION

ClinicalTrials.gov ISRCTN49407852.

Measuring disease levels in myeloma using flow cytometry in combination with other laboratory techniques: Lessons from the past 20 years at the Leeds Haematological Malignancy Diagnostic Service

People with myeloma who obtain a good response to treatment have a better survival if sensitive molecular or flow-cytometric techniques show no detectable minimal residual disease (MRD). The application of MRD techniques to clinical trials is now considered to be increasingly important because treatment approaches are sufficiently effective that using survival outcomes is slowing down the identification of the best new treatments. The articles in this issue consider the laboratory requirements for harmonization of MRD analysis by flow cytometry but there are practical considerations that are also important in implementing a myeloma MRD assay in the cytometry laboratory. In particular, it is important to consider when to request, and how best to utilize, a bone marrow aspirate sample because the procedure is invasive and the cells obtained are valuable for a number of different investigations. This brief article considers some experience obtained over two decades of implementing a service for MRD detection, initially as a scientific bolt-on to clinical trials through to a routine clinical diagnostic assay.

Minimal Residual Disease Assessed by Multiparameter Flow Cytometry in Multiple Myeloma: Impact on Outcome in the Medical Research Council Myeloma IX Study

Purpose

To investigate the prognostic value of minimal residual disease (MRD) assessment in patients with multiple myeloma treated in the MRC (Medical Research Council) Myeloma IX trial.

Patients and Methods

Multiparameter flow cytometry (MFC) was used to assess MRD after induction therapy (n = 378) and at day 100 after autologous stem-cell transplantation (ASCT; n = 397) in intensive-pathway patients and at the end of induction therapy in non–intensive-pathway patients (n = 245).

Results

In intensive-pathway patients, absence of MRD at day 100 after ASCT was highly predictive of a favorable outcome (PFS, P < .001; OS, P = .0183). This outcome advantage was demonstrable in patients with favorable and adverse cytogenetics (PFS, P = .014 and P < .001, respectively) and in patients achieving immunofixation-negative complete response (CR; PFS, P = .0068). The effect of maintenance thalidomide was assessed, with the shortest PFS demonstrable in those MRD-positive patients who did not receive maintenance and longest in those who were MRD negative and did receive thalidomide (P < .001). Further analysis demonstrated that 28% of MRD-positive patients who received maintenance thalidomide became MRD negative. MRD assessment after induction therapy in the non–intensive-pathway patients did not seem to be predictive of outcome (PFS, P = .1).

Conclusion

MRD assessment by MFC was predictive of overall outcome in patients with myeloma undergoing ASCT. This predictive value was seen in patients achieving conventional CR as well as patients with favorable and adverse cytogenetics. The effects of maintenance strategies can also be evaluated, and our data suggest that maintenance thalidomide can eradicate MRD in some patients.

Flow cytometry and its use in the diagnosis and management of mature lymphoid malignancies

The last decade has seen major advances in flow cytometric immunophenotyping and this has expanded the utility of flow cytometry to investigate the antigens present on normal and neoplastic haematopoietic cells. This review summarizes how flow cytometry is used currently in the diagnosis and management of mature lymphoid malignancies. The establishment of disease-specific phenotypes allows the creation of assays which can detect neoplastic cells with high specificity and sensitivity. Certain lymphoid neoplasms are well defined immunophenotypically, while others are more heterogeneous. The availability of more sophisticated cytometers and a wider selection of antibodies in routine diagnostic laboratories will lead to the resolution of these more complex disease entities.