Phase I-II trial of bortezomib plus oral cyclophosphamide and prednisone in relapsed and refractory multiple myeloma

Better quality of response to lenalidomide plus dexamethasone is associated with improved clinical outcomes in patients with relapsed or refractory multiple myeloma

BACKGROUND

This retrospective pooled analysis of two phase III trials (MM-009/MM-010) compared clinical outcomes of patients who achieved a complete response or very good partial response to treatment with lenalidomide plus dexamethasone with the outcomes of those who only achieved a partial response.

DESIGN AND METHODS

Patients (n=353) received lenalidomide (25 mg/day for 21 days of each 28-day cycle) plus dexamethasone (40 mg on days 1-4, 9-12, and 17-20 for four cycles, and only on days 1-4 after the first four cycles). Time to response, duration of response, time-to-progression, overall survival, and adverse events were investigated for patients who had a complete or very good partial response and compared with those of patients who had a partial response.

RESULTS

At the time of unblinding, 32% of patients had achieved a complete or very good partial response and 28% had a partial response. Half (50.5%) of the patients who had a partial response as their initial response achieved a complete or very good partial response with further treatment. The probability of achieving a complete or very good partial response with continued lenalidomide treatment decreased with delayed achievement of a partial response (by cycle 4 versus later); however, it remained clinically significant. With an extended follow-up of 48 months, the median response duration, time-to-progression, and overall survival were longer in patients with a complete or very good partial response than in those with a partial response (24.0 versus 8.3 months, P<0.001; 27.7 versus 12.0 months, P<0.001; not reached versus 44.2 months, P=0.021, respectively). The benefit of a complete or very good partial response was independent of when it was achieved.

CONCLUSIONS

Continuing treatment with lenalidomide plus dexamethasone to achieve best response, in the absence of disease progression and toxicity, provided deeper remissions and greater clinical benefit over time for patients in this study.

Advances in treatment for relapses and refractory multiple myeloma

Recent advances in the treatment of multiple myeloma have resulted in improved response rates and overall survival in patients with multiple myeloma. These advances are largely due to thalidomide-, lenalidomide-, and bortezomib-based combinations that have improved response rates, not only in patients with untreated disease, but also in those with relapsed and/or refractory myeloma, in some cases producing response rates up to 85%. Eventually, however, nearly all patients relapse, emphasizing a continuing role for the introduction of investigational agents that overcome drug resistance. This article will review the current role for thalidomide, lenalidomide, and bortezomib-based combinations, as well as some preliminary findings for promising investigational agents currently in clinical trials for patients with relapsed and/or refractory disease.

Relapsed multiple myeloma

Advances in treatment options for patients with multiple myeloma have made a significant impact on the overall survival of patients and have helped achieve levels of response and duration of remission previously not achievable with standard chemotherapy-based approaches. These improvements are due, in large part, to the development of the novel agents thalidomide, bortezomib, and lenalidomide, each of which has substantial single-agent activity. In addition, a large number of second-generation agents are also in clinical development, such that the repertoire of available treatment options continues to expand. To better interpret clinical trials performed in the relapsed setting, it is important that definitions of relapse categories are used to help better pinpoint the specific benefit for a given therapy, especially in the combination therapy setting as it aids in determining if ongoing work should be continued or abandoned for a given new agent. Insights from preclinical modeling and in vitro work have identified several new combinations, new targets and second- or third-generation versions of existing targets that hold great promise in the setting of relapsed myeloma. Combinations of thalidomide, bortezomib, and lenalidomide with conventional agents or among each other have resulted in enhanced response rates and efficacy. Clinical trials of agents such as carfilzomib, pomalidomide, vorinostat, panobinostat, and elotuzomab are just a few of the many exciting new compounds that are being tested in phase 1 and phase 2 clinical trials for relapsed patients. Further clinical and translational testing are critical to better understanding how best to combine these new agents, as well as identifying patient populations that may best benefit from treatment with these developing new agents.

Evidence-based mini-review: treatment options for patients with relapsed/refractory myeloma previously treated with novel agents and high-dose chemotherapy and autologous stem-cell transplantation

A 64 year-old man with a history of multiple myeloma presents with new back pain. He has a history of International Staging System stage 1, IgG kappa multiple myeloma with normal cytogenetics which was diagnosed 4 years ago when he presented with a pathological fracture of the left humerus. He was initially managed with mechanical stabilization and 4 cycles of bortezomib-dexamethasone, as well as 2 years of bisphosphanates. Following induction therapy he achieved a very good partial response (VGPR). He subsequently received high-dose melphalan and autologous stem cell transplantation (auto-SCT) and achieved a complete reponse (CR) post-transplant. He did not receive maintenance therapy and had been lost-to follow-up for about a year. He now presents 5 years after initial diagnosis with back pain and is noted to have a new lytic lesion with a compression fracture at T8. A serum protein electrophoresis demonstrates reappearance of his original monoclonal protein. After appropriate stabilization he comes to you to discuss additional treatment options.

Novel agents for relapsed and/or refractory multiple myeloma

The introduction of novel agents, such as thalidomide, bortezomib, and lenalidomide, has altered the landscape of therapeutic options for multiple myeloma by offering new mechanisms for targeting this disease. Combinations of these agents, with each other and/or traditional chemotherapeutics, have vastly increased the treatment options for patients both frontline, and at relapse, providing higher response rates, and importantly, increasing median overall survival. In this review, we will discuss the use of these novel agents and their combinations in patients with relapsed and/or refractory multiple myeloma.

The development and pharmacology of proteasome inhibitors for the management and treatment of cancer

The ubiquitin-proteasome complex is an important molecular target for the design of novel chemotherapeutics. This complex plays a critical role in signal transduction pathways important for tumor cell growth and survival, cell-cycle control, transcriptional regulation, and the modulation of cellular stress responses to endogenous and exogenous stimuli. The sensitivity of transformed cells to proteasome inhibitors and the successful design of treatment protocols with tolerable, albeit narrow, therapeutic indices have made proteasome inhibition a viable strategy for cancer treatment. Clinical validation of the proteasome as a molecular target was achieved with the approval of bortezomib, a boronic acid proteasome inhibitor, for the treatment of multiple myeloma and mantle cell lymphoma. Several "next-generation" proteasome inhibitors (carfilzomib and PR-047, NPI-0052, and CEP-18770) representing distinct structural classes (peptidyl epoxyketones, beta-lactones, and peptidyl boronic acids, respectively), mechanisms of action, pharmacological and pharmacodynamic activity profiles, and therapeutic indices have now entered clinical development. These agents may expand the clinical utility of proteasome inhibitors for the treatment of solid tumors and for specific non-oncological, i.e., inflammatory disease, indications as well. This chapter addresses the biology of the proteasome, the medicinal chemistry and mechanisms of action of proteasome inhibitors currently in clinical development, the preclinical and clinical pharmacological and safety profiles of bortezomib and the newer compounds against hematological and solid tumors. Future directions for research and other applications for this novel class of therapeutics agents are considered in this chapter.

DSMM XI study: dose definition for intravenous cyclophosphamide in combination with bortezomib/dexamethasone for remission induction in patients with newly diagnosed myeloma

A clinical trial was initiated to evaluate the recommended dose of cyclophosphamide in combination with bortezomib and dexamethasone as induction treatment before stem cell transplantation for younger patients with newly diagnosed multiple myeloma (MM). Thirty patients were treated with three 21-day cycles of bortezomib 1.3 mg/m(2) on days 1, 4, 8, and 11 plus dexamethasone 40 mg on the day of bortezomib injection and the day after plus cyclophosphamide at 900, 1,200, or 1,500 mg/m(2) on day 1. The maximum tolerated dose of cyclophosphamide was defined as 900 mg/m(2). At this dose level, 92% of patients achieved at least a partial response. The overall response rate [complete response (CR) plus partial response (PR)] across all dose levels was 77%, with a 10% CR rate. No patient experienced progressive disease. The most frequent adverse events were hematological and gastrointestinal toxicities as well as neuropathy. The results suggest that bortezomib in combination with cyclophosphamide at 900 mg/m(2) and dexamethasone is an effective induction treatment for patients with newly diagnosed MM that warrants further investigation.

Proteasome inhibitors in the treatment of multiple myeloma

Targeting intracellular protein turnover by inhibiting the ubiquitin-proteasome pathway as a strategy for cancer therapy is a new addition to our chemotherapeutic armamentarium, and has seen its greatest successes against multiple myeloma. The first-in-class proteasome inhibitor, bortezomib, was initially approved for treatment of patients in the relapsed/refractory setting as a single agent, and was recently shown to induce even greater benefits as part of rationally designed combinations that overcome chemoresistance. Modulation of proteasome function is also a rational approach to achieve chemosensitization to other antimyeloma agents, and bortezomib has now been incorporated into the front-line setting. Bortezomib-based induction regimens are able to achieve higher overall response rates and response qualities than was the case with prior standards of care, and unlike these older approaches, maintain efficacy in patients with clinically and molecularly defined high-risk disease. Second-generation proteasome inhibitors with novel properties, such as NPI-0052 and carfilzomib, are entering the clinical arena, and showing evidence of antimyeloma activity. In this spotlight review, we provide an overview of the current state of the art use of bortezomib and other proteasome inhibitors against multiple myeloma, and highlight areas for future study that will further optimize our ability to benefit patients with this disease.

Pomalidomide (CC4047) Plus Low-Dose Dexamethasone As Therapy for Relapsed Multiple Myeloma

Purpose

Thalidomide and lenalidomide are immunomodulatory drugs (IMiDs) that produce high remission rates in the treatment of multiple myeloma. Pomalidomide is a new IMiD with high in vitro potency. We report, to our knowledge, the first phase II trial of pomalidomide administered in combination with low-dose dexamethasone for the treatment of relapsed or refractory multiple myeloma.

Patients and Methods

Pomalidomide was administered orally at a dose of 2 mg daily on days 1 through 28 of a 28-day cycle. Dexamethasone 40 mg daily was administered orally on days 1, 8, 15, and 22 of each cycle. Responses were recorded using the criteria of the International Myeloma Working Group.

Results

Sixty patients were enrolled. Thirty-eight patients (63%) achieved confirmed response including complete response in three patients (5%), very good partial response in 17 patients (28%), and partial response in 18 patients (30%). Responses were seen in 40% of lenalidomide-refractory patients, 37% of thalidomide-refractory patients, and 60% of bortezomib-refractory patients. Responses were seen in 74% of patients with high-risk cytogenetic or molecular markers. Toxicity consisted primarily of myelosuppression. Grade 3 or 4 hematologic toxicity consisted of anemia (5%), thrombocytopenia (3%), and neutropenia (32%). One patient (1.6%) had a thromboembolic event. The median progression-free survival time was 11.6 months and was not significantly different in patients with high-risk disease compared with patients with standard-risk disease.

Conclusion

The combination of pomalidomide and low-dose dexamethasone is extremely active in the treatment of relapsed multiple myeloma, including high response rates in patients refractory to other novel agents.

The ubiquitin-proteasome system in cancer, a major player in DNA repair. Part 2: transcriptional regulation

DNA repair is an indispensable part of a cell's defence system against the devastating effects of DNA-damaging conditions. The regulation of this function is a really demanding situation, particularly when the stressing factors persist for a long time. In such cases, the depletion of existing DNA repair proteins has to be compensated by the induction of the analogous gene products. In addition, the arrest of transcription, which is another result of many DNA-damaging agents, needs to be overcome through regulation of transcription-specific DNA repair pathways. The involvement of the ubiquitin-proteasome system (UPS) in cancer- and chemotherapy-related DNA-damage repair relevant to the above transcriptional modification mechanisms are illustrated in this review. Furthermore, the contribution of UPS to the regulation of localization and accessibility of DNA repair proteins to chromatin, in response to cellular stress is discussed.

Treatment of relapsed/refractory multiple myeloma

The introduction of several novel and active treatments and improvements in supportive care of myeloma patients has resulted in a prolongation of the survival of these patients. However, myeloma remains an incurable disease and almost all patients will relapse. Effective management of the relapsing/refractory disease incorporates several different strategies, depending on prior treatments, responses, and duration of responses, as well as residual toxicity, age, and physical condition. High-dose dexamethasone still has a role in the management of disease complications such as cytopenias, renal impairment, or spinal cord compression until another agent is added. High-dose therapy may be considered for selected patients who have a long-term treatment-free interval after their first transplantation. Allogeneic transplantation is limited to selected young patients, preferably with an HLA-matched donor. However, the backbone of current strategies for the management of relapsed/refractory myeloma includes the novel agents thalidomide, bortezomib, and lenalidomide. These agents, either with dexamethasone or in combination with chemotherapy, have shown significant activity both in relapsed and in refractory patients. Based on the results of phase III trials, lenalidomide and bortezomib have increased the post-relapse survival and are active in patients who have received prior novel agents; lenalidomide is active in thalidomide-pretreated or bortezomib-pretreated patients and bortezomib alone or in combination with chemotherapy is active in thalidomide/lenalidomide-pretreated patients. Combinations of novel agents show synergistic activity and may overcome drug resistance. Finally, special consideration is needed for the management of patients with renal impairment or other poor prognostic features.

Clinical development of novel proteasome inhibitors for cancer treatment

BACKGROUND

Emerging evidence demonstrates that targeting the tumor proteasome is a promising strategy for cancer therapy.

OBJECTIVE

This review summarizes recent results from cancer clinical trials using specific proteasome inhibitors or some natural compounds that have proteasome-inhibitory effects.

METHODS

A literature search was carried out using PubMed. Results about the clinical application of specific proteasome inhibitors and natural products with proteasome-inhibitory activity for cancer prevention or therapy were reviewed.

RESULTS/CONCLUSION

Bortezomib, the reversible proteasome inhibitor that first entered clinical trials, has been studied extensively as a single agent and in combination with glucocorticoids, cytotoxic agents, immunomodulatory drugs and radiation as treatment for multiple myeloma and other hematological malignancies. The results in some cases have been impressive. There is less evidence of bortezomib's efficacy in solid tumors. Novel irreversible proteasome inhibitors, NPI-0052 and carfilzomib, have also been developed and clinical trials are underway. Natural products with proteasome-inhibitory effects, such as green tea polyphenol (-)-epigallocatechin-3-gallate (EGCG), soy isoflavone genistein, and the spice turmeric compound curcumin, have been studied alone and in combination with traditional chemotherapy and radiotherapy against various cancers. There is also interest in developing these natural compounds as potential chemopreventive agents.

New generation pharmacotherapy in elderly multiple myeloma patients

BACKGROUND

Observational databases have demonstrated that the overall prognosis of multiple myeloma patients has markedly improved over the past decade, yet the greatest strides have been attained in younger rather than older patients.

OBJECTIVE

To review recent clinical trials that include new generation agents (thalidomide, lenalidomide and bortezomib) and autologous stem cell transplantation in older multiple myeloma patients.

RESULTS

Conventional regimens such as melphalan plus prednisone can be improved with the addition of thalidomide or bortezomib: more patients attain complete and near-complete remission, and progression-free survival rates are nearly doubled. In addition, autologous hematopoietic stem cell transplantation studies show that this treatment approach can be used successfully in selected older myeloma patients in whom the toxicity profile of autotransplant and resulting overall survival may be similar to that obtained in the younger patient group.

CONCLUSIONS

In the advanced-age population, implementation of new therapies results in significant benefits in older as well as younger patients.

NFkappaB signaling in carcinogenesis and as a potential molecular target for cancer therapy

It has become increasingly clear that deregulation of the NFkappaB signaling cascade is a common underlying feature of many human ailments including cancers. The past two decades of intensive research on NFkappaB has identified the basic mechanisms that govern the functioning of this pathway but uncovering the details of why this pathway works differently in different cellular contexts or how it interacts with other signaling pathways remains a challenge. A thorough understanding of these processes is needed to design better and more efficient therapeutic approaches to treat complex diseases like cancer. In this review, we summarize the literature documenting the involvement of NFkappaB in cancer, and then focus on the approaches that are being undertaken to develop NFkappaB inhibitors towards treatment of human cancers.

Cyclophosphamide, bortezomib and dexamethasone induction for newly diagnosed multiple myeloma: high response rates in a phase II clinical trial

We have studied a three drug combination with bortezomib, cyclophosphamide and dexamethasone (CyBorD) on a 28 day cycle in the treatment of newly diagnosed multiple myeloma patients to assess response and toxicity. The primary endpoint of response was evaluated after four cycles. Thirty-three newly diagnosed, symptomatic patients with multiple myeloma received bortezomib 1.3 mg/m² intravenously on days 1, 4, 8, 11, cyclophosphamide 300 mg/m² orally days 1, 8, 15, 22 and dexamethasone 40 mg orally days 1-4, 9-12, 17-20 on a 28 day cycle for four cycles. Responses were rapid with a mean 80% decline in the sentinel monoclonal protein at the end of two cycles. The overall intent to treat response rate (≥ partial response) was 88% with 61% ≥VGPR and 39% CR/nCR. For the 28 patients that completed all 4 cycles of therapy the CR/nCR rate was 46% and ≥VGPR rate 71%. All patients undergoing stem cell harvest had a successful collection. Twenty three patients underwent SCT and are evaluable through day 100 with CR/nCR documented in 70% and ≥VGPR in 74%. In conclusion, CyBorD produces a rapid and profound response in patients with newly diagnosed multiple myeloma with manageable toxicity.

Novel therapies for relapsed myeloma

Treatment of myeloma relapse needs to be individualized to reflect the effectiveness and toxicities of prior therapies, with consideration given to pragmatic issues such as the tempo of relapse, age of the patient, access to drugs and patient preference. In general, combination therapies have been associated with higher response rates and improved progression-free survival and may be preferable when a rapid response is required. Nevertheless, in a slower-tempo relapse it is unclear at this juncture whether sequencing of drugs or multi-agent combinations offer superior overall survival results. Fortunately, active novel agents that offer further possibilities for some myeloma patients have become available in clinical trials. In this review we will describe the various classes of novel drugs being tested and the pros and cons of preclinical testing, and will particularly focus on two agents with single-agent activity in myeloma: carfilzomib, a proteasome inhibitor, and pomalidomide, a member of the immunomodulatory class of drugs.