Carfilzomib in multiple myeloma patients with renal impairment: pharmacokinetics and safety

Salvage therapy of multiple myeloma: the new generation drugs

During the past decade, overall results of treatment of multiple myeloma (MM) have been improved and survival curves are now significantly better with respect to those obtained with historical treatment. These improvements are linked to a deeper knowledge of the biology of disease and to the introduction in clinical practice of drugs with different mechanism of action such as proteasome inhibitors and immunomodulatory drugs (IMiDs). However, MM remains in most cases an incurable disease. For patients who relapse after treatment with novel agents, the prognosis is dismal and new drugs and therapeutic strategies are required for continued disease control. In this review, we summarize new insights in salvage therapy for relapsed/refractory MM as emerging from recent clinical trials exploring the activity of bendamustine, new generation proteasome inhibitors, novel IMiDs, monoclonal antibodies, and drugs interfering with growth pathways.

Incidence and management of adverse events in patients with relapsed and/or refractory multiple myeloma receiving single-agent carfilzomib

Carfilzomib, a selective proteasome inhibitor approved in the USA in 2012, is a single agent for relapsed and refractory multiple myeloma. Carfilzomib is administered as a 2–10-minute infusion on days 1, 2, 8, 9, 15, and 16 of a 28-day cycle at a starting dose of 20 mg/m² for cycle 1 and a target dose of 27 mg/m² thereafter. In the pivotal Phase II study (PX-171-003-A1), carfilzomib 20/27 mg/m² provided durable responses in a heavily pretreated population with relapsed and refractory multiple myeloma (n=266), with an overall response rate of 22.9% and a median duration of response of 7.8 months. In an integrated safety analysis of four Phase II studies, common adverse events (32.7%–55.5%) included fatigue, anemia, nausea, thrombocytopenia, dyspnea, and diarrhea. Grade 3/4 adverse events were generally hematologic and included thrombocytopenia (23.4%), anemia (22.4%), and lymphopenia (18.1%). Serious adverse events included pneumonia (9.9%), acute renal failure (4.2%), pyrexia (3.4%), and congestive heart failure (3.4%). New or worsening peripheral neuropathy was infrequent (13.9% overall, 1.3% grade 3, no grade 4). This review discusses findings of the integrated safety analysis and provides practical experience from a single institution in managing treatment-related and disease-related adverse events. Individualized treatment with proactive management of side effects and complications allows patients with advanced multiple myeloma to remain on carfilzomib for extended periods.

New drugs and novel mechanisms of action in multiple myeloma in 2013: a report from the International Myeloma Working Group (IMWG)

Treatment in medical oncology is gradually shifting from the use of nonspecific chemotherapeutic agents toward an era of novel targeted therapy in which drugs and their combinations target specific aspects of the biology of tumor cells. Multiple myeloma (MM) has become one of the best examples in this regard, reflected in the identification of new pathogenic mechanisms, together with the development of novel drugs that are being explored from the preclinical setting to the early phases of clinical development. We review the biological rationale for the use of the most important new agents for treating MM and summarize their clinical activity in an increasingly busy field. First, we discuss data from already approved and active agents (including second- and third-generation proteasome inhibitors (PIs), immunomodulatory agents and alkylators). Next, we focus on agents with novel mechanisms of action, such as monoclonal antibodies (MoAbs), cell cycle-specific drugs, deacetylase inhibitors, agents acting on the unfolded protein response, signaling transduction pathway inhibitors and kinase inhibitors. Among this plethora of new agents or mechanisms, some are specially promising: anti-CD38 MoAb, such as daratumumab, are the first antibodies with clinical activity as single agents in MM. Moreover, the kinesin spindle protein inhibitor Arry-520 is effective in monotherapy as well as in combination with dexamethasone in heavily pretreated patients. Immunotherapy against MM is also being explored, and probably the most attractive example of this approach is the combination of the anti-CS1 MoAb elotuzumab with lenalidomide and dexamethasone, which has produced exciting results in the relapsed/refractory setting.

A novel Bruton's tyrosine kinase inhibitor CC-292 in combination with the proteasome inhibitor carfilzomib impacts the bone microenvironment in a multiple myeloma model with resultant antimyeloma activity

Bruton's tyrosine kinase (Btk) modulates B-cell development and activation and has an important role in antibody production. Interestingly, Btk may also affect human osteoclast (OC) function; however, the mechanism was unknown. Here we studied a potent and specific Btk inhibitor, CC-292, in multiple myeloma (MM). In this report, we demonstrate that, although CC-292 increased OC differentiation, it inhibited OC function via inhibition of c-Src, Pyk2 and cortactin, all involved in OC-sealing zone formation. As CC-292 did not show potent in vitro anti-MM activity, we next evaluated it in combination with the proteasome inhibitor, carfilzomib. We first studied the effect of carfilzomib on OC. Carfilzomib did not have an impact on OC-sealing zone formation but significantly inhibited OC differentiation. CC-292 combined with carfilzomib inhibited both sealing zone formation and OC differentiation, resulting in more profound inhibition of OC function than carfilzomib alone. Moreover, the combination treatment in an in vivo MM mouse model inhibited tumor burden compared with CC-292 alone; it also increased bone volume compared with carfilzomib alone. These results suggest that CC-292 combined with carfilzomib augments the inhibitory effects against OC within the bone microenvironment and has promising therapeutic potential for the treatment of MM and related bone disease.

The emerging role of carfilzomib combination therapy in the management of multiple myeloma

Carfilzomib is a proteasome inhibitor that selectively and irreversibly binds to its target, resulting in sustained inhibition absent of off-target effects relative to bortezomib. Single-agent carfilzomib has produced robust and durable responses in clinical trials and it has been approved in the US for treating relapsed and refractory multiple myeloma (MM). Due to its favorable safety profile, carfilzomib is particularly suitable for use in combination strategies. Promising data have been reported from studies that investigated the use of carfilzomib in combination with immunomodulators, alkylating agents, glucocorticoids, histone deacetylase inhibitors and kinesin spindle protein inhibitors. Ongoing pivotal randomized Phase III studies are investigating the efficacy and safety of carfilzomib combinations in patients with relapsed MM and transplant ineligible patients.

Future agents and treatment directions in multiple myeloma

The development of bortezomib and immunomodulatory agents resulted in a revolution in the treatment of multiple myeloma (MM). Moreover, second-generation proteasome inhibitors (carfilzomib) and immunomodulatory agents (pomalidomide) have recently been approved. Nevertheless, the incurability of this disease requires other drugs with different mechanisms of action to either prolong the survival of patients refractory to current therapies, or achieve cure. Active research has been done exploring the pathogenesis of MM and searching for novel, druggable targets. In this regard, some of these novel agents seem promising, such as monoclonal antibodies (anti-CD38 - daratumumab or anti-CS1 - elotuzumab) or the kinesin protein inhibitor Arry-520. Other agents under investigation are kinase inhibitors, signaling pathways inhibitors or deacetylase inhibitors. With so many novel agents under investigation, future therapy in MM will probably involve the combined use of the already approved drugs with some of those newly discovered.

Current strategies for treatment of relapsed/refractory multiple myeloma

In spite of significant advances in the management of multiple myeloma (MM), the disease remains incurable and nearly all patients ultimately relapse and require salvage chemotherapy. As such, relapsed and relapsed-refractory MM remains a critical area of research pertaining to biological mechanisms of progression and chemotherapy resistance, as well as to the development of new pharmacologic agents and immunologic approaches for the disease. The immunomodulatory agents and proteasome inhibitors represent the cornerstone of treatment in this setting, with combination regimens incorporating these drugs demonstrating encouraging rates and duration of response, including the newer agents, pomalidomide and carfilzomib. In addition, novel drug classes have shown promising activity in RR MM, including the orally-administered proteasome inhibitors ixazomib and oprozomib; monoclonal antibodies such as the anti-CS1 monoclonal antibody elotuzumab and anti-CD38 monoclonal antibody daratumumab; and histone deacetylase inhibitors such as panobinostat and rocilinostat.

New drugs in multiple myeloma - role of carfilzomib and pomalidomide

Carfilzomib (CFZ), an epoxyketone with specific chymotrypsin-like activity, is a second-generation proteasome inhibitor with significant activity in patients with relapsed and refractory multiple myeloma. On July 20, 2012, the US Food and Drug Administration approved CFZ to treat patients with multiple myeloma who have received at least two prior therapies including bortezomib (BORT) and an immunomodulatory agent and have demonstrated disease progression on or within 60 days of completion of the last therapy. Cytogenetic abnormalities did not appear to have a significant impact on the CFZ activity. Carfilzomib was well tolerated and demonstrated promising efficacy in patients with renal insufficiency. Pomalidomide (POM) (CC-4047) is a novel immunomodulatory derivative (IMID) with a stronger in vitro anti-myeloma effect compared with “older” IMIDs – thalidomide and lenalidomide (LEN). On February 8, 2013, the US Food and Drug Administration approved POM (Pomalyst, Celgene) for the treatment of MM patients who have received at least two prior therapies including LEN and BORT and have demonstrated progression on or within 60 days of completion of the last therapy. Pomalidomide is a novel IMID with significant anti-myeloma activity and manageable toxicity. This compound has shown high efficacy in MM patients who were resistant to prior use of LEN/BORT as well as in patients with a high-risk cytogenetic profile. Carfilzomib and POM have very high efficacy and will be used also in first line therapy in future.

Carfilzomib: a next-generation proteasome inhibitor for multiple myeloma treatment

Although the incidence of multiple myeloma (MM) is increasing, the median overall survival and the number of agents in the pipeline for treating MM also are increasing. Response rates higher than 80% are not uncommon in the frontline setting when the novel agents thalidomide, lenalidomide, and bortezomib are used in combination. Response rates and survival also have improved in disease that has relapsed after treatment with conventional therapies. The focus of research has now shifted to improving survival and disease response in patients refractory to current treatment paradigms. New agents are targeting new pathways, as well as existing mechanisms known to be effective, but with different safety profiles. Carfilzomib is a potent, selective, irreversible inhibitor of the ubiquitin-proteasome pathway. The drug is a next-generation proteasome inhibitor found to be safe and effective for patients with relapsed and refractory MM, where treatment options are limited. As with any newly approved agent, one should recognize that drugs within the same class will be administered differently and often cause dissimilar treatment-related toxicities. Oncology nurses are crucial to the successful administration of chemotherapeutic agents such as carfilzomib, and an understanding of management techniques is paramount to quality patient care.

Phase 2 dose-expansion study (PX-171-006) of carfilzomib, lenalidomide, and low-dose dexamethasone in relapsed or progressive multiple myeloma

We previously reported a phase 1b dose-escalation study of carfilzomib, lenalidomide, and low-dose dexamethasone (CRd) in relapsed or progressive multiple myeloma where the maximum planned dose (MPD) was carfilzomib 20 mg/m2 days 1 and 2 of cycle 1 and 27 mg/m2 days 8, 9, 15, 16, and thereafter; lenalidomide 25 mg days 1 to 21; and dexamethasone 40 mg once weekly on 28-day cycles. Herein, we present results from the phase 2 dose expansion at the MPD, focusing on the 52 patients enrolled in the MPD cohort. Median follow-up was 24.4 months. In the MPD cohort, overall response rate (ORR) was 76.9% with median time to response of 0.95 month (range, 0.5-4.6) and duration of response (DOR) of 22.1 months. Median progression-free survival was 15.4 months. ORR was 69.2% in bortezomib-refractory patients and 69.6% in lenalidomide-refractory patients with median DOR of 22.1 and 10.8 months, respectively. A median of 9.5 (range, 1-45) carfilzomib cycles were started with 7.7% of patients requiring carfilzomib dose reductions and 19.2% discontinuing CRd due to adverse events (AEs). Grade 3/4 AEs included lymphopenia (48.1%), neutropenia (32.7%), thrombocytopenia (19.2%), and anemia (19.2%). CRd at the MPD was well tolerated with robust, rapid, and durable responses.

Integrated safety profile of single-agent carfilzomib: experience from 526 patients enrolled in 4 phase II clinical studies

Carfilzomib, a selective proteasome inhibitor, was approved in 2012 for the treatment of relapsed and refractory multiple myeloma. Safety data for single-agent carfilzomib have been analyzed for 526 patients with advanced multiple myeloma who took part in one of 4 phase II studies (PX-171-003-A0, PX-171-003-A1, PX-171-004, and PX-171-005). Overall analyses of adverse events and treatment modifications are presented, as well as specific analyses of adverse events by organ system. Overall, the most common adverse events of any grade included fatigue (55.5%), anemia (46.8%), and nausea (44.9%). In the grouped analyses, any grade adverse events were reported in 22.1% for any cardiac (7.2% cardiac failure), 69.0% for any respiratory (42.2% dyspnea), and 33.1% for any grouped renal impairment adverse event (24.1% increased serum creatinine). The most common non-hematologic adverse events were generally Grade 1 or 2 in severity, while Grade 3/4 adverse events were primarily hematologic and mostly reversible. There was no evidence of cumulative bone marrow suppression, either neutropenia or thrombocytopenia, and febrile neutropenia occurred infrequently (1.1%). Notably, the incidence of peripheral neuropathy was low overall (13.9%), including patients with baseline peripheral neuropathy (12.7%). Additionally, the incidence of discontinuations or dose reductions attributable to adverse events was low. These data demonstrate that single-agent carfilzomib has an acceptable safety profile in heavily pre-treated patients with relapsed/refractory multiple myeloma. The tolerable safety profile allows for administration of full-dose carfilzomib, both for extended periods and in a wide spectrum of patients with advanced multiple myeloma, including those with pre-existing comorbidities.

Kidney disease and multiple myeloma

Kidney injury is a common complication of multiple myeloma and other plasma cell dyscrasias, and it is associated with increased mortality. Multiple pathogenic mechanisms can contribute to kidney injury in the patient with myeloma, some of which are the result of nephrotoxic monoclonal Ig and some of which are independent of paraprotein deposition. The pathogenic mechanisms that underlie paraprotein-related kidney disease are increasingly well understood. A novel assay allowing the quantification of free light chains in the serum has aided the diagnosis of new onset disease and allowed for the earlier detection of relapse. Novel myeloma agents have shown considerable promise in reversing renal failure in some patients and improving outcomes. Stem cell transplantation remains a mainstay of management for younger patients with myeloma who are suitable candidates for intensive therapy, whereas the role of new drugs, plasma exchange, and kidney transplantation continues to evolve.

Treatment outcomes in patients with relapsed and refractory multiple myeloma and high-risk cytogenetics receiving single-agent carfilzomib in the PX-171-003-A1 study

Several cytogenetic abnormalities are associated with poor outcomes in multiple myeloma (MM). We prospectively analyzed the impact of cytogenetic abnormalities on outcomes during the phase 2 PX-171-003-A1 study of single-agent carfilzomib for relapsed and refractory MM. In the response-evaluable population (257/266), fluorescence in situ hybridization (FISH)/conventional cytogenetic profiles were available for 229 patients; 62 (27.1%) had high-risk cytogenetics—del 17p13, t(4;14) or t(14;16) by interphase FISH or deletion 13 or hypodiploidy by metaphase cytogenetics—and 167 (72.9%) had standard-risk profiles. Generally, baseline characteristics were similar between the subgroups, but International Staging System stage III disease was more common in high- vs standard-risk patients (41.9% vs 27.5%) as was Eastern Cooperative Oncology Group performance status 1/2 (85.5% vs 68.3%). Overall response was comparable between the subgroups (25.8% vs 24.6%, respectively; P=0.85), while time-to-event end points showed a trend of shorter duration in high-risk patients, including median duration of response (5.6 months (95% confidence interval (CI) 3.7–7.8) vs 8.3 months (95% CI 5.6–12.3)) and overall survival (9.3 (95% CI 6.5–13.0) vs 19.0 months (95% CI 15.4–NE); P=0.0003). Taken together, these findings demonstrate that single-agent carfilzomib is efficacious and has the potential to at least partially overcome the impact of high-risk cytogenetics in heavily pre-treated patients with MM.

Carfilzomib: a novel agent for multiple myeloma

OBJECTIVES

Carfilzomib is a new agent for the treatment of relapsed and refractory multiple myeloma (MM). This article presents a comprehensive overview of the pharmacokinetics, pharmacodynamics, dosing schedule, safety, efficacy, preparation and administration of carfilzomib, and its role in treating MM patients.

KEY FINDINGS

Carfilzomib is a selective proteasome inhibitor that differs structurally and mechanistically from bortezomib. In patients' whole-blood and peripheral-blood mononuclear cells, carfilzomib inhibited proteasomal and immunoproteasomal activity by 70-80%. Approved carfilzomib dosing is based on body surface area, and is given on days 1, 2, 8, 9, 15 and 16 of a 28-day cycle (20 mg/m(2) in cycle 1; 27 mg/m(2) in cycle 2+). Premedication with dexamethasone and adequate hydration are recommended to reduce the risk of adverse events. The median t1/2 of carfilzomib is short (0.29-0.48 h), with no accumulation detected between doses. In clinical studies in relapsed and refractory MM. and in combinations in newly diagnosed MM, single-agent carfilzomib demonstrated significant durable activity, good tolerability and a favourable safety profile, supporting its extended use.

CONCLUSIONS

Carfilzomib represents an important addition to the treatment armamentarium for patients with relapsed and/or refractory MM, and studies are underway evaluating the role of single-agent carfilzomib in additional clinical settings as well as in different combinations.