Use of endpoints in multiple myeloma randomized controlled trials over the last 15 years: A systematic review

Surrogate endpoints are being used more frequently in randomized controlled trials, even though they do not consistently corelate with patient outcomes. We systemically evaluated the use of surrogate endpoints in multiple myeloma randomized controlled trials over the past 15 years. We searched three databases (Pubmed, Embase, Cochrane) for multiple myeloma randomized controlled trials from January 1, 2005 to December 30, 2019. The primary outcome of our study was the proportion of randomized controlled trials that used overall survival as their primary endpoint. Secondary outcomes included the use of surrogate endpoints, and trends over time, and whether they differed based on study sponsorship. We included 151 randomized controlled trials in our analysis. The primary endpoint was overall survival (OS) in 17 (11.3%) of studies, progression free survival (PFS) or event-defined endpoints in 91 studies (60.3%) and response-based endpoints in 44 studies (29.1%). Quality of life was a primary endpoint in only three studies (2%). The use of OS as a primary endpoint decreased from 28.5% of trials from 2005 to 2009 to 5.5% from 2015 to 2019. There has been a decrease in the clinically meaningful endpoint of OS over the past 15 years in multiple myeloma randomized controlled trials. Use of quality of life as a primary endpoint remains exceedingly low. It remains paramount to recognize that the use of surrogate endpoints is imperfect, and care based upon them requires constant physician and patient re-analysis.

Long-Term Efficacy of Maintenance Therapy for Multiple Myeloma: A Quantitative Synthesis of 22 Randomized Controlled Trials

We aimed to quantitatively synthesize data from randomized controlled trials (RCTs) concerning maintenance for multiple myeloma (MM). We searched electronic literature databases and conference proceedings to identify relevant RCTs. We selected eligible RCTs using predefined selection criteria. We conducted meta-analysis comparing maintenance containing new agents and conventional maintenance, and subgroup analysis by transplantation status and mainstay agent as well. We performed trial sequential analysis (TSA) to determine adequacy of sample size for overall and subgroup meta-analyses. We performed network meta-analysis (NMA) to compare and rank included regimens. A total of 22 RCTs involving 9,968 MM patients and 15 regimens were included, the overall quality of which was adequate. Significant heterogeneity was detected for progression-free survival (PFS) but not overall survival (OS). Meta-analyses showed that maintenance containing new agents significantly improved PFS but not OS [PFS: Hazard Ratio (HR) = 0.59, 95% Confidence Interval (CI) = 0.54 to 0.64; OS: HR = 0.93, 95% CI = 0.87 to 1.00], compared with controls. Subgroup analyses revealed lenalidomide (Len)-based therapies better than thalidomide-based ones (HR = 0.50 and 0.66, respectively; P = 0.001). NMA revealed that most of the maintenance regimens containing new agents were significantly better than simple observation in terms of PFS but not OS. Len single agent was the most effective, considering PFS and OS both. We concluded that conventional maintenance has very limited effect. Maintenance containing new agents is highly effective in improving PFS, but has very limited effect on OS. Maintenance with Len may have the largest survival benefits. Emerging strategies may further change the landscape of maintenance of MM.

Frontline therapy for multiple myeloma: a concise review of the evidence based on randomized clinical trials

The past decade has seen significant progress in the development of new and effective therapies for multiple myeloma. Stem cell transplantation and the introduction of novel agents, such as thalidomide, lenalidomide, and bortezomib, have significantly improved outcomes of myeloma patients. In the current review, we analyzed the available data provided by published randomized clinical trials for the frontline therapy of myeloma patients. We attempted to assess the relative contribution and impact of these new therapies in the setting of both, transplant eligible and transplant ineligible patients.

An old drug with a new future: bendamustine in multiple myeloma

INTRODUCTION

Bendamustine is a unique bifunctional alkylating agent with promising activity in multiple myeloma (MM). It is currently licensed in Europe for use as frontline treatment with prednisolone for patients with MM who are unsuitable for transplantation and who are contraindicated for thalidomide and bortezomib therapy.

AREAS COVERED

Studies evaluating the safety and efficacy of bendamustine administered alone or in combination in both the upfront and relapse settings of MM patients, including those with renal insufficiency, were reviewed. The use of bendamustine as conditioning for autologous stem-cell transplantation and the possibility of stem-cell mobilization after bendamustine therapy are discussed.

EXPERT OPINION

Bendamustine seems to be efficacious either in monotherapy or in combination with other drugs in previously treated or untreated patients. This is due to its unique mechanism of action including its ability to activate apoptosis and inhibit mitotic checkpoints, making it potentially more effective than other alkylating agents. Moreover, it has an acceptable toxicity profile and is suitable for patients with renal impairment. Finally, this drug does not seem to compromise the possibility of achieving a stem-cell mobilization. Nonetheless, data from Phase III studies demonstrating its effectiveness in terms of overall survival are not yet available.

Risk of secondary primary malignancies in maintenance therapy for multiple myeloma

SUMMARY There have been many advances in the treatment of patients with multiple myeloma over the past decade. As a result, the average life expectancy of patients with MM has improved. New medications, including immunomodulatory drugs (thalidomide, lenalidomide and pomalidomide) and proteasome inhibitors (bortezomib and carfilzomib) have entered clinical practice. On average, these medications are easier to tolerate than traditional chemotherapy allowing for long-term use of these drugs in a maintenance fashion. Clinical trials have appeared to establish the benefit of lower dose maintenance therapy for MM patients after induction chemotherapy and/or autologous stem cell transplant. These medications have been shown to improve not only the progression-free survival of patients, but also improve their overall survival compared with observation alone in some pivotal studies. With long-term maintenance therapy, a notable increase in secondary primary malignancies has been described. The exact mechanism behind this increase is uncertain, but may relate to the persistence of CD34+ cells in the setting of continued immunomodulatory exposure. Despite the concern of secondary primary malignancies, the risk:benefit ratio still favors maintenance therapy in many patients with multiple myeloma.

Perspectives in the treatment of multiple myeloma

INTRODUCTION

The development of proteasome inhibitor (PI) and immunomodulatory drugs (IMiDs) and advances in supportive care have considerably changed the treatment paradigm of multiple myeloma (MM) and significantly improved survival. Nevertheless, almost all patients show disease relapse and develop drug resistance.

AREAS COVERED

We review the prognostic stratification and therapeutic strategy for newly diagnosed MM patients. Furthermore, mechanisms of drug resistance are discussed. Data regarding newer drugs, currently undergoing examination, such as PI (carfilzomib, ONX0912, MLN9708, and marizomib), IMiDs (pomalidomide), histone deacetylase inhibitors (vorinostat and panobinostat), kinase inhibitors (temsirolimus, everolimus, and tanespimycin), and immune-based therapies (elotuzumab, siltuximab, MOR03087, and MMBT062) are reported.

EXPERT OPINION

The use of three to four drug combination therapies including PI and IMiDs has significantly impacted on MM patient outcome. Moreover, new insights into MM biology from high-throughput technologies and availability of newer and more efficacious drugs will continue to influence our approach to MM treatment. In the immediate future molecular subgroup-specific trials using targeted agents may represent a very important step toward evaluating impact of interfering with relevant signaling pathways in MM. With the continued rapid evolution of progress in this field, MM will become a chronic illness having sustained complete response in a significant number of patients.

Emerging biological insights and novel treatment strategies in multiple myeloma

INTRODUCTION

Survival in multiple myeloma (MM) has improved significantly in the past 10 years due to new treatments, such as thalidomide and lenalidomide (immunomodulatory drugs or IMiDs) bortezomib and advances in supportive care. Nevertheless, almost all MM patients show disease relapse and develop drug resistance.

AREAS COVERED

The authors review the therapeutic approach for untreated MM patients. Furthermore, the prognostic stratification of patients and the proposed risk-adapted strategy are discussed. Finally, preclinical and clinical data regarding newer antimyeloma agents, currently undergoing examination such as proteasome inhibitors (PIs, carfilzomib), IMiDs (pomalidomide), epigenetic agents (histone deacetylase inhibitors vorinostat and panobinostat), humanized monoclonal antibodies (elotuzumab and MOR03087) and targeted therapies (inhibitors of NF-κB, MAPK, HSP90 and AKT) are reported.

EXPERT OPINION

MM patient outcome has remarkably improved due to the use of three to four drug combination therapies including PIs and IMiDs, which target the tumor in its bone marrow microenvironment, however MM treatment remains challenging. The use of high-throughput techniques has allowed to discover new insights into MM biology. The identification of candidate therapeutic targets and availability of respective investigative agents will allow for a substantial progress in the development and implementation of personalized medicine in MM.

Lenalidomide in multiple myeloma: Current status and future potential

The clinical development of lenalidomide (Revlimid™), then pomalidomide (Actimid™) as members of immunomodulatory drugs (IMiDs) for the treatment of multiple myeloma (MM), exemplifies how insight into disease biology can lead to design of effective therapeutic agents. Increased experience and understanding of IMiD's diverse biological effects has lead to rational design of lenalidomide-based treatment-regimens over recent years. However, much about lenalidomide is yet to be understood and fully exploited. Here, we review what is known of lenalidomide's biological effects, clinical certainties and uncertainties in the treatment of MM, and explore its future potential with other synergistic therapeutic agents.

Thalidomide maintenance therapy for patients with multiple myeloma: meta-analysis

We performed a meta-analysis of randomized controlled trials comparing thalidomide maintenance with other regimens after induction chemotherapy for multiple myeloma. Overall, 6 trials including 2786 patients were identified. Patients treated with thalidomide maintenance had marginally better overall survival (hazard ratio HR 0.83, P=0.07). The improvement was especially prominent in a subgroup of studies using corticosteroids with thalidomide (HR 0.70, P=0.02). Thalidomide improved progression-free survival (HR 0.65, P<0.01), but had more frequent venous thrombosis (risk difference 0.024, P<0.05) and peripheral neuropathy (risk difference 0.072, P<0.01). These results suggest that thalidomide maintenance with corticosteroids is effective in prolonging survival for multiple myeloma.

The rise, fall and subsequent triumph of thalidomide: lessons learned in drug development

Perhaps no other drug in modern medicine rivals the dramatic revitalization of thalidomide. Originally marketed as a sedative, thalidomide gained immense popularity worldwide among pregnant women because of its effective anti-emetic properties in morning sickness. Mounting evidence of human teratogenicity marked a dramatic fall from grace and led to widespread social, legal and economic ramifications. Despite its tragic past thalidomide emerged several decades later as a novel and highly effective agent in the treatment of various inflammatory and malignant diseases. In 2006 thalidomide completed its remarkable renaissance becoming the first new agent in over a decade to gain approval for the treatment of plasma cell myeloma. The catastrophic collapse yet subsequent revival of thalidomide provides important lessons in drug development. Never entirely abandoned by the medical community, thalidomide resurfaced as an important drug once the mechanisms of action were further studied and better understood. Ongoing research and development of related drugs such as lenalidomide now represent a class of irreplaceable drugs in hematological malignancies. Further, the tragedies associated with this agent stimulated the legislation which revamped the FDA regulatory process, expanded patient informed consent procedures and mandated more transparency from drug manufacturers. Finally, we review recent clinical trials summarizing selected medical indications for thalidomide with an emphasis on hematologic malignancies. Herein, we provide a historic perspective regarding the up-and-down development of thalidomide. Using PubMed databases we conducted searches using thalidomide and associated keywords highlighting pharmacology, mechanisms of action, and clinical uses.

Cyclophosphamide, thalidomide, and dexamethasone (CTD) as initial therapy for patients with multiple myeloma unsuitable for autologous transplantation

As part of the randomized MRC Myeloma IX trial, we compared an attenuated regimen of cyclophosphamide, thalidomide, and dexamethasone (CTDa; n = 426) with melphalan and prednisolone (MP; n = 423) in patients with newly diagnosed multiple myeloma ineligible for autologous stem-cell transplantation. The primary endpoints were overall response rate, progression-free survival, and overall survival (OS). The overall response rate was significantly higher with CTDa than MP (63.8% vs 32.6%; P < .0001), primarily because of increases in the rate of complete responses (13.1% vs 2.4%) and very good partial responses (16.9% vs 1.7%). Progression-free survival and OS were similar between groups. In this population, OS correlated with the depth of response (P < .0001) and favorable interphase fluorescence in situ hybridization profile (P < .001). CTDa was associated with higher rates of thromboembolic events, constipation, infection, and neuropathy than MP. In elderly patients with newly diagnosed multiple myeloma (median age, 73 years), CTDa produced higher response rates than MP but was not associated with improved survival outcomes. We highlight the importance of cytogenetic profiling at diagnosis and effective management of adverse events. This trial was registered at International Standard Randomized Controlled Trials Number as #68454111.

The role of bortezomib, thalidomide and lenalidomide in the management of multiple myeloma: an overview of clinical and economic information

Bortezomib, thalidomide and lenalidomide can be aimed at treating patients with newly diagnosed multiple myeloma (both eligible and ineligible for transplantation) as well as those with relapsed or refractory disease. This review analysed the available clinical and economic data on these three drugs. Irrespective of which of the three agents is considered, the magnitude of the benefit in newly diagnosed cases (transplanted or non-transplanted) tends to be between 10 and 20 months per patient in terms of progression-free survival or survival; the survival benefit is smaller in relapsed or refractory disease. In addition, a single-institution observational analysis evaluated the outcomes in nearly 3000 consecutive patients examined between 1971 and 2006. The survival in patients diagnosed between 2001 and 2006 was longer than that observed in patients diagnosed between 1994 and 2000. This finding supports the conclusion that novel agents provide a survival improvement compared with traditional therapy. Formal cost-effectiveness studies on these three agents are still lacking. A MEDLINE search retrieved only four short papers or letters and no full-length analysis. Hence, the cost effectiveness of these agents needs further investigation, with separate assessments of the different therapeutic settings. In a simplified analysis, we tried to contrast the average cost of treatment for each of the novel agents versus their respective benefit, expressed in quality-adjusted survival. Despite its preliminary nature, our assessment indicates that the cost effectiveness of these three agents is likely to be within commonly accepted pharmacoeconomic thresholds.

Rates of venous thromboembolism in multiple myeloma patients undergoing immunomodulatory therapy with thalidomide or lenalidomide: a systematic review and meta-analysis

INTRODUCTION

The incidence of venous thromboembolism (VTE) in patients with multiple myeloma (MM) treated with thalidomide- and lenalidomide-based regimens is high. Recent observational studies have suggested that thromboprophylaxis might be efficacious in decreasing the risk of VTE in this population.

PURPOSE

To determine the absolute rates of VTE with and without different thromboprophylactic agents in patients with newly diagnosed or previously treated MM receiving thalidomide- or lenalidomide-based regimens.

RESULTS

Patients with newly diagnosed MM treated with thalidomide in combination with dexamethasone have a VTE risk of 4.1 (95% CI, 2.8-5.9) per 100 patient-cycles. Therapeutic doses of anticoagulants seem to provide the largest absolute risk reduction of VTE. The rate of VTE in patients with previously treated MM receiving thalidomide in combination with dexamethasone is 0.8 (95% CI, 0.1-2.1) per 100 patient-months. A combination of lenalidomide and dexamethasone is associated with of risk of VTE of 0.8 (95% CI, 0.07-2.0) per 100 patient-cycles and 0.7 (95% CI, 0.4-0.9) per 100 patient-cycles in patients with newly diagnosed and previously treated MM, respectively. Similarly, the rates of VTE in patients also receiving thromboprophylaxis with aspirin were 0.9 (95% CI, 0.5-1.5) and 0.6 (95% CI, 0.01-2.1), respectively.

CONCLUSION

Patients with newly diagnosed or previously treated MM receiving thalidomide- or lenalidomide-based regimens in combination with dexamethasone are at high risk of VTE. The benefit of various types of thromboprophylaxis is difficult to quantify in patients with MM receiving immunomodulatory therapy, especially in those receiving lenalidomide-based therapy or who have previously treated MM. Randomized controlled trials are needed to address this important clinical need.

Combination of IFN-α/Gm-CSF as a Maintenance Therapy for Multiple Myeloma Patients After Autologous Stem Cell Transplantation (ASCT): A Prospective Phase II Study

Interferon alpha (IFN-α) has been used as a maintenance therapy after autologous stem cell transplantation (ASCT) for multiple myeloma (MM) patients. In this study, we combined GM-CSF with IFN-α in order to improve IFN tolerance in post-ASCT myeloma patients. Primary aims were to evaluate myelotoxicity and effectiveness of this maintenance therapy. The treatment included 4 × 10⁶ units of IFN-α and 125 μg/m² of GM-CSF given three times a week for twelve months. Twenty seven patients were enrolled within 120 days after ASCT. One patient discontinued treatment due to thrombocytopenia and seven others were taken off study due to flu-like symptoms and/or increase in liver enzymes. With a median follow-up of 45.5 months, the median overall survival was not reached while the median progression-free survival was 28 months. Eleven patients (42%) have remained in very good partial remission or complete remission since ASCT. In conclusion, our results demonstrate that maintenance with GM-CSF and IFN-α is safe and effective.

Management of treatment-related adverse events in patients with multiple myeloma

The introduction of novel antimyeloma therapies, including thalidomide, lenalidomide and bortezomib, has expanded treatment options for patients with multiple myeloma. These compounds alter the natural history of multiple myeloma and help improve outcomes, but have different and specific toxicity profiles. The major adverse events associated with these treatments are somnolence (thalidomide), venous thromboembolism (thalidomide and lenalidomide), myelosuppression (lenalidomide and bortezomib), gastrointestinal disturbance, and peripheral neuropathy (thalidomide and bortezomib). These adverse events are predictable, consistent, and manageable with patient monitoring, supportive care, and dose reduction and interruption where appropriate. Herein we evaluate the incidence of treatment-related adverse events associated with each of these compounds. We further review the management of these adverse events with a view to delivering optimal therapeutic outcomes in patients with newly diagnosed and relapsed and/or refractory multiple myeloma.

Thalidomide maintenance treatment increases progression-free but not overall survival in elderly patients with myeloma

BACKGROUND

Thalidomide maintenance therapy after stem cell transplantation resulted in increased progression-free survival and overall survival in a few trials, but its role in non-transplant eligible patients with multiple myeloma remains unclear. This study assessed the impact of thalidomide-interferon in comparison to interferon maintenance therapy in elderly patients with multiple myeloma.

DESIGN AND METHODS

Of 289 elderly patients with multiple myeloma who were randomized to thalidomide-dexamethasone or melphalan-prednisolone induction therapy, 137 finally completed 9 cycles of induction therapy with stable disease or better and thereby qualified for maintenance treatment. Of these, 128 have been randomized to either thalidomide-interferon or interferon alone. Primary study endpoints were progression-free survival and response rates; secondary endpoints were overall survival, toxicity and quality of life.

RESULTS

Thalidomide-interferon maintenance therapy led to a significantly longer progression-free survival compared to interferon (27.7 vs. 13.2 months, P=0.0068), but overall survival was similar in both groups (52.6 vs. 51.4 months, P=0.81) and did not differ between patients aged 75 years or older, or younger patients (P=0.39). Survival after disease progression tended to be shorter in patients on thalidomide-interferon maintenance therapy (P=0.056). Progression-free survival and overall survival tended to be shorter in patients with adverse cytogenetic (FISH) findings compared to the standard risk group but differences were not significant (P=0.084 and P=0.082, respectively). Patients on thalidomide-interferon presented with more neuropathy (P=0.0015), constipation (P=0.0004), skin toxicity (P=0.0041) and elevated creatinine (P=0.026).

CONCLUSIONS

Thalidomide plus interferon maintenance therapy increased progression-free survival but not overall survival and was associated with slightly more toxicity than maintenance with interferon alone. (ClinicalTrials.gov Identifier: NCT00205751).