Retrospective study of treatment patterns and outcomes post-lenalidomide for multiple myeloma in Canada.

Lenalidomide is an important component of initial therapy in newly diagnosed multiple myeloma, either as maintenance therapy post-autologous stem cell transplantation (ASCT) or as first-line therapy with dexamethasone for patients' ineligible for ASCT (non-ASCT). This retrospective study investigated treatment patterns and outcomes for ASCT-eligible and -ineligible patients who relapsed after lenalidomide as part of first-line therapy, based on data from the Canadian Myeloma Research Group Database for patients treated between January 2007 and April 2019. Among 256 patients who progressed on lenalidomide maintenance therapy, 28.5% received further immunomodulatory derivative-based (IMiD-based) therapy (lenalidomide/pomalidomide) without a proteasome inhibitor (PI) (bortezomib/carfilzomib/ixazomib), 26.2% received PI-based therapy without an IMiD, 19.5% received both an IMiD plus PI, 13.5% received daratumumab-based regimens, and 12.1% underwent salvage ASCT. Median progression-free survival (PFS) was longest for daratumumab-based therapy (22.7 months) and salvage ASCT (23.4 months) and ranged from 6.6 to 7.3 months for the other treatments (P < .0001). Median overall survival (OS) was also longest for daratumumab and salvage ASCT. A total of 87 non-ASCT patients received subsequent therapy, with 66.7% receiving bortezomib-based therapy and 13.8% receiving other PI-based therapy. Median PFS was 15.4 and 24.8 months for bortezomib-based and other PI-based therapy, respectively (P = .404). During most of the study period, daratumumab was not funded; in this setting, switching to a different therapeutic class following relapse on lenalidomide produced the longest remissions for non-ASCT patients. Further prospective studies are warranted to determine optimum treatment following relapse on lenalidomide, especially in the light of increased access to daratumumab.

Weekly carfilzomib plus cyclophosphamide and dexamethasone in the treatment of relapsed/refractory multiple myeloma: Final results from the MCRN-003/MYX.1 single arm phase II trial.

The MCRN-003/CCTGMYX.1 is a single arm phase II trial of weekly carfilzomib, cyclophosphamide and dexamethasone (wKCd), exploring a convenient immunomodulator (IMiD)-free regimen in relapsed myeloma. Weekly carfilzomib (20/70 mg/m2 ), dexamethasone 40 mg and cyclophosphamide 300 mg/m2 was delivered over 28-day cycles. The primary endpoint was overall response after four cycles. Secondary endpoints included toxicity, response depth, PFS and OS. Exploratory endpoints included the impact of cytogenetics, prior therapy exposure and serum free light chain (sFLC) escape; 76 patients were accrued. The ORR was 85% (68% ≥very good partial response [VGPR] and 29% ≥complete response [CR]). The median OS and PFS were 27 and 17 months respectively. High-risk cytogenetics conferred a worse ORR (75% vs. 97%, p = .013) and median OS (18 months vs. NR, p = .002) with a trend toward a worse median PFS (14 vs. 22 months, p = .06). Prior proteasome inhibitor (PI) or lenalidomide did not influence OS or PFS. The sFLC was noted in 15% of patients with a median PFS of 17 months when included as a progression event. The most common ≥ grade 3 non-hematologic adverse events were infectious (40%), vascular (17%) and cardiac (15%). The wKCD is a safe and effective regimen in relapse, especially for patients ineligible for lenalidomide-based therapies.

Long-term follow-up from a phase 1/2 study of single-agent bortezomib in relapsed systemic AL amyloidosis.

CAN2007 was a phase 1/2 study of once- and twice-weekly single-agent bortezomib in relapsed primary systemic amyloid light chain amyloidosis (AL) amyloidosis. Seventy patients were treated, including 18 and 34 patients at the maximum planned doses on the once- and twice-weekly schedules. This prespecified final analysis provides mature response and long-term outcomes data after 3-year additional follow-up since the last report. In the once-weekly 1.6 mg/m(2) and twice-weekly 1.3 mg/m(2) bortezomib groups, final hematologic response rates were 68.8% and 66.7%; 80% of patients in each group sustained their response for ≥1 year. One-year progression-free rates were 72.2% and 76.8%. Median overall survival (OS) was 62.1 months and not reached; 4-year OS rates were 75.0% and 63.0%. Low baseline difference in κ/λ free light-chain level was associated with higher hematologic complete response rates and longer OS. At data cutoff, 40 (57%) patients had received subsequent therapy, including 19 (27%) retreated with bortezomib, 11 (58%) of whom achieved complete or partial hematologic responses. Four patients received prolonged bortezomib for between 3.5 and 5.6 years, with no new safety concerns, highlighting the feasibility of long-term therapy. Single-agent bortezomib produced durable hematologic responses and promising long-term OS in relapsed AL amyloidosis. This trial was registered at www.clinicaltrials.gov as #NCT00298766.

Phase I-II trial of oral cyclophosphamide, prednisone and lenalidomide for the treatment of patients with relapsed and refractory multiple myeloma.

This single institution, open label Phase I-II dose escalation trial evaluated the safety and efficacy of the combination of lenalidomide (Revlimid®), cyclophosphamide and prednisone (CPR) in patients with relapsed/refractory multiple myeloma. The maximal administered dose of CPR consisted of cyclophosphamide 300 mg/m(2) on day 1, 8, and 15, lenalidomide 25 mg on d 1-21 and prednisone 100 mg every other day in a 28-d cycle. Between November 2007 and June 2009, 32 patients were entered in cohorts of three at three dose levels. The median age was 64 years, 59% were male, with a median two prior regimens. Responding patients could stay on treatment until progression. The full-dose CPR regimen produced no dose-limiting toxicity and was delivered for a median of 16 months (3·5-65 months) with acceptable safety and tolerance. The overall response rate (≥ partial response) was 94% at a median follow up of 28 months. The median progression-free survival was 16·1 months [95% confidence interval (CI); 10·9-22·5 months], while the median overall survival was 27·6 months (95% CI; 16·8-36·6 months). Only the beta-2 microglobulin level at protocol entry correlated with a better survival (P = 0·047). These observations compare favourably with other 2- and 3- drug combinations for relapsed/refractory myeloma, and suggest that CPR should be evaluated further in the setting of relapsed/refractory disease, or in newly diagnosed patients.

Safety and efficacy of targeted-dose busulfan and bortezomib as a conditioning regimen for patients with relapsed multiple myeloma undergoing a second autologous blood progenitor cell transplantation.

Patients with multiple myeloma (MM) who relapse after autologous transplantation have limited therapeutic options. We conducted a prospective, multicenter, phase IIa study to investigate the safety and efficacy of i.v. busulfan (Bu) in combination with bortezomib as a conditioning regimen for a second autotransplantation. Because a safe Bu exposure was unknown in patients receiving this combination, Bu was initially targeted to a total area under the concentration-time curve (AUC) of 20,000 µM × minute. As no concentration-limiting toxicity was observed in 6 patients, this Bu exposure was utilized in the following treatment cohort (n = 24). Individualized Bu dose, based on test dose .8 mg/kg pharmacokinetics (PK), was administered daily for 4 consecutive days starting 5 days before transplantation, followed by a single dose of bortezomib (1.3 mg/m(2)) 1 day before transplantation. The total mean dose of i.v. Bu (including the test dose and 4-day administration) was 14.2 mg/kg (standard deviation = 2.48; range, 8.7 to 19.2). Confirmatory PK demonstrated that only 2 of 30 patients who underwent transplantation were dosed outside the Bu AUC target and dose adjustments were made for the last 2 doses of i.v. Bu. The median age was 59 years (range, 48 to 73). Median time from first to second transplantation was 28.0 months (range, 12 to 119). Of 26 evaluable patients, 10 patients attained a partial response (PR) or better at 3 months after transplantation, with 2 patients attaining a complete response. At 6 months after transplantation, 5 of 12 evaluable patients had maintained or improved their disease status. Median progression-free survival was 191 days, whereas median overall survival was not reached during the study period. The most common grade 3 and 4 toxicities were febrile neutropenia (50.0%) and stomatitis (43.3%). One transplantation-related death was observed. A combination of dose-targeted i.v. Bu and bortezomib induced PR or better in one third of patients with MM who underwent a second autotransplantation, with acceptable toxicity.

Autologous stem cell transplant is an effective therapy for carefully selected patients with AL amyloidosis: experience of a single institution.

Autologous stem-cell transplant has been widely used to treat patients with AL amyloidosis. However, transplant-related mortality rates are high, and a recent randomized trial suggested that non-transplant regimens produced comparable results with less toxicity. In order to define the role of patient selection in stem cell transplantation, we evaluated 78 consecutive AL amyloidosis patients transplanted at our centre. Transplant-related mortality occurred in 11·5%. Complete haematological response and organ response were achieved in 56% and 60%. Median overall survival was significantly lower for patients with brain-type natriuretic peptide (BNP) >300 pg/ml (17·5 months vs. not-reached) (P = 0·0004), troponin-I >0·07 ng/ml (13·5 months vs. not-reached) (P = 0·00001) and those not achieving a complete haematological response (88 months vs. not-reached) (P = 0·0345); high BNP and troponin-I were the most important predictive factors in a multivariate analysis. Based on this study, patients with BNP <300 pg/ml and/or normal levels of troponin-I should be considered transplant candidates.

Carfilzomib in multiple myeloma: gold, silver, or bronze?

In this issue of Blood, Siegel and colleagues report that the next-generation proteasome inhibitor carfilzomib, when administered as a single agent, can produce meaningful disease control in heavily pretreated patients with relapsed/refractory multiple myeloma.(1)

Central nervous system involvement with multiple myeloma: long term survival can be achieved with radiation, intrathecal chemotherapy, and immunomodulatory agents.

Involvement of the central nervous system (CNS) in multiple myeloma (MM) is a rare complication, with reported survival of <6 months. This report describes 37 MM patients with leptomeningeal and/or parenchymal brain involvement treated at our institution and identifies factors associated with long-term survival. From January 1999 to December 2010, 37 patients with CNS MM were evaluated at our institution. Clinical characteristics, treatment and survival were retrospectively collected. CNS disease was present at MM diagnosis in 24% and at relapse in 76%. Plasma cell leukemia (40%) and skull plasmacytomas (65%) were common, suggesting haematological and contiguous spread. Intrathecal (IT) chemotherapy was used in 81%, cranial and/or spinal irradiation in 78%, and various systemic therapies [immunomodulatory agents (IMiDs) (51%), cisplatin-based (DPACE; cisplatin, doxorubicin, cyclophosphamide, etoposide) (27%), bortezomib (19%), alkylators (11%), dexamethasone alone (8%), auto-transplant (5%)]. Median survival from CNS disease was only 4·6 months [95% confidence interval (CI): 2·8-6·7]; however, nine patients had prolonged survival (median: 17·1 months, 95% CI: 13·2-67·4). In general, these long-term survivors were treated with radiotherapy, multi-dosing IT chemotherapy, and IMiD-containing therapy. CNS MM is a highly aggressive disease but in our experience, long-term survival can be achieved with the combination of multi-dosing IT chemotherapy, radiation and IMiD-based therapy.

Efficacy and safety of once-weekly and twice-weekly bortezomib in patients with relapsed systemic AL amyloidosis: results of a phase 1/2 study.

This first prospective phase 2 study of single-agent bortezomib in relapsed primary systemic AL amyloidosis evaluated the recommended (maximum planned) doses identified in phase 1 testing (1.6 mg/m² once weekly [days 1, 8, 15, and 22; 35-day cycles]; 1.3 mg/m² twice weekly [days 1, 4, 8, and 11; 21-day cycles]). Among all 70 patients enrolled in the study, 44% had ≥ 3 organs involved, including 73% and 56% with renal and cardiac involvement. In the 1.6 mg/m² once-weekly and 1.3 mg/m² twice-weekly groups, the hematologic response rate was 68.8% and 66.7% (37.5% and 24.2% complete responses, respectively); median time to first/best response was 2.1/3.2 and 0.7/1.2 months, and 78.8% and 75.5% had response durations of ≥ 1 year, respectively. One-year hematologic progression-free rates were 72.2% and 74.6%, and 1-year survival rates were 93.8% and 84.0%, respectively. Outcomes appeared similar in patients with cardiac involvement. Among all 70 patients, organ responses included 29% renal and 13% cardiac responses. Rates of grade ≥ 3 toxicities (79% vs 50%) and discontinuations/dose reductions (38%/53% vs 28%/22%) resulting from toxicities appeared higher with 1.3 mg/m² twice-weekly versus 1.6 mg/m² once-weekly dosing. Both bortezomib dose schedules represent active, well-tolerated regimens in relapsed AL amyloidosis. This study was registered at www.clinicaltrials.gov as #NCT00298766.

Lenalidomide, bortezomib, pegylated liposomal doxorubicin, and dexamethasone in newly diagnosed multiple myeloma: a phase 1/2 Multiple Myeloma Research Consortium trial.

This phase 1/2 trial evaluated combination lenalidomide, bortezomib, pegylated liposomal doxorubicin, and dexamethasone (RVDD) in newly diagnosed multiple myeloma (MM) patients. Patients received RVDD at 4 dose levels, including the maximum tolerated dose (MTD). Patients with a very good partial response or better (≥ VGPR) after cycle 4 proceeded to autologous stem cell transplantation or continued treatment. The primary objectives were MTD evaluation and response to RVDD after 4 and 8 cycles. Seventy-two patients received a median of 4.5 cycles. The MTDs were lenalidomide 25 mg, bortezomib 1.3 mg/m(2), pegylated liposomal doxorubicin 30 mg/m(2), and dexamethasone 20/10 mg, as established with 3-week cycles. The most common adverse events were fatigue, constipation, sensory neuropathy, and infection; there was no treatment-related mortality. Response rates after 4 and 8 cycles were 96% and 95% partial response or better, 57% and 65% ≥ VGPR, and 29% and 35% complete or near-complete response, respectively. After a median follow-up of 15.5 months, median progression-free survival (PFS) and overall survival (OS) were not reached. The estimated 18-month PFS and OS were 80.8% and 98.6%, respectively. RVDD was generally well tolerated and highly active, warranting further study in newly diagnosed MM patients. This trial was registered at www.clinicaltrials.gov as NCT00724568.

Second autologous stem cell transplantation as salvage therapy for multiple myeloma: impact on progression-free and overall survival.

The role of a second autologous stem cell transplant (ASCT) as salvage therapy is unclear, particularly with the availability of novel agents to treat progressive multiple myeloma (MM). We retrospectively reviewed all MM patients who received a second ASCT as salvage therapy at our center from March 1992 to December 2009. Eighty-one MM patients received a second ASCT for relapsed MM. The median time to relapse after first transplant was 39 months (9.83-100). All patients received reinduction therapy before the second ASCT. The high-dose regimen given before the second ASCT consisted of melphalan (MEL) alone in the majority. Complete response, very good partial response, and partial response were seen in 7.7%, 39.7%, and 50%, respectively, at day 100 post-ASCT; the median time to relapse after the second ASCT was 19 months. Early deaths occurred in 2.6%. Median progression-free survival (PFS) based on the time to myeloma relapse after first ASCT was 9.83 months (relapse ≤ 24 months) and 17.3 months (relapse ≥ 24 months) (P < .05). Median overall survival (OS) was 28.47 months (relapse ≤ 24 months) and 71.3 months (relapse >24 months) (P = .006). Second ASCT is a feasible and safe option for salvage therapy in MM. The best outcome was observed in patients whose time to progression was >24 months after first ASCT, as these patients had a subsequent PFS lasting over 1 year and an OS of almost 6 years.

A comparison of lenalidomide/dexamethasone versus cyclophosphamide/lenalidomide/dexamethasone versus cyclophosphamide/bortezomib/dexamethasone in newly diagnosed multiple myeloma.

Novel agents are considered standard components of induction therapy for newly diagnosed patients with multiple myeloma. We retrospectively compared the results of three consecutive phase 2 clinical trials; RD (lenalidomide/dexamethasone, n=34), CRD (cyclophosphamide/lenalidomide/dexamethasone, n=53) and CyBorD (cyclophosphamide/bortezomib/dexamethasone, n=63) (N=150). Response rates after four cycles of treatment were: ≥near complete response (nCR), 12% vs. 2% vs. 41%, P<0·0001 and very good partial response or better, 35% vs. 30% vs. 65%, P=0·0003, respectively. With all cycles of therapy considered, ≥nCR was 35%, 15% and 41%, P=0·006. However, there is no evidence that one regimen produced superior progression-free survival (PFS) (median: 3·2 vs. 2·3 vs. 2·7years, P=0·11) or overall survival (3-year: 88% vs. 79% vs. 88%, P=0·23). Transplantation did not impact PFS (median: 2·7 vs. 2·3 years, P=0·41) but was associated with improved OS (3-year: 93% vs. 75%, P≤0·001). High genetic risk patients (n=40) had earlier relapse despite lenalidomide or bortezomib (median: 2·1 vs. 2·7years, P=0·45). Grade 3/4 toxicities were least with CyBorD while CRD had most toxicity. In conclusion, CyBorD demonstrated superior responses and less frequent serious toxicity but more neuropathy when compared to RD and CRD. Importantly, 80% of patients treated with modern therapeutic approaches are alive at 4years.

Weekly and twice-weekly bortezomib in patients with systemic AL amyloidosis: results of a phase 1 dose-escalation study.

New treatment options are required for primary systemic AL amyloidosis (AL). This phase 1 dose-escalation component of a phase 1/2 study in relapsed AL aimed to determine the maximum tolerated dose (MTD) of bortezomib once weekly (0.7-1.6 mg/m(2); days 1, 8, 15, and 22; 35-day cycles) and twice weekly (0.7-1.3 mg/m(2); days 1, 4, 8, and 11; 21-day cycles) and assess preliminary hematologic responses. Thirty-one patients with relapsed AL were enrolled across 7 cohorts. Dose-limiting toxicity included grade 3 congestive heart failure in 2 patients (1 at once weekly, 1.6 mg/m(2), and 1 at twice weekly, 1.0 mg/m(2)). MTD was not defined for either schedule; the maximum doses of 1.6 mg/m(2) (once weekly) and 1.3 mg/m(2) (twice weekly) are being used in phase 2 evaluation. Most commonly reported toxicities on both schedules included gastrointestinal events, fatigue, and nervous system disorders. Discontinuations and dose reductions for toxicity were reported in 12 and 4 patients, respectively. No treatment-related deaths occurred. Hematologic responses occurred in 15 (50%) of 30 evaluable patients, including 6 (20%) complete responses. Median time to first response was 1.2 months. Once-weekly and twice-weekly bortezomib appear generally well tolerated in relapsed AL, with promising hematologic responses. This study is registered with http://ClinicalTrials.Gov under identifier NCT00298766.

Cyclophosphamide and prednisone induction followed by cyclophosphamide mobilization effectively decreases the incidence of engraftment syndrome in patients with POEMS syndrome who undergo stem cell transplantation.

High-dose chemotherapy with autologous stem cell transplantation (ASCT) can achieve excellent clinical responses in patients with POEMS syndrome (Jimenez Zepeda et al., Blood 2010;116:2403; Gertz et al., Am J Hematol 2005;79:319-328; Gherardi et al., Ann Neurol 1994;35:501-505; Gattinoni et al., Nat Rev Immunol 2006;6:383-393; Salem et al., J Immunol 2009;182:2030-2040; Salem et al., Cancer Immunol Immunother 2010;59:341-353; Salem et al., Cell Immunol 2010;261:134-143). However, High-dose melphalan with ASCT should be considered carefully due to its treatment-related morbidity (Vuckovic et al., Blood 2003;101:2314-2317), especially in patients with poor performance status owing to polyneuropathy and multiorgan involvement, such as cardiac, respiratory, and renal failure. Significant increases in the concentration of circulating macrophage colony-stimulating factor, erythropoietin, IL-6, and TNF-α, reach near maximal values at approximately day +12, predating neutrophil engraftment, and clinically manifest with fever, rash and edema (Dispenzieri et al., Eur J Haematol 2008;80:397-406). Depending on the definition used, approximately 50% of patients satisfied criteria for engraftment syndrome (ES) (Vuckovic et al., Blood 2003;101:2314-2317). ES occurs in 27-47% of patients who undergo ASCT; mortality rate is reported from 8% to 18% (Gattinoni et al., Nat Rev Immunol 2006;6:383-393; Vuckovic et al., Blood 2003;101:2314-2317). We have therefore reviewed our experience with ASCT in patients with POEMS syndrome who were treated with cyclophosphamide and prednisone as induction therapy followed by cyclophosphamide mobilization with an emphasis on treatment-related morbidity and frequency of ES. Our study confirms that ASCT is a feasible and efficacious treatment for patients with POEMS syndrome. In addition, the use of CP followed by cyclophosphamide mobilization decreases the incidence of PES leading to less morbidity and mortality rates.

Race and outcomes of autologous hematopoietic cell transplantation for multiple myeloma.

Blacks are twice as likely to develop and die from multiple myeloma (MM), and are less likely to receive an autologous hematopoietic-cell transplant (AHCT) for MM compared to Whites. The influence of race on outcomes of AHCT for MM is not well described. We compared the probability of overall survival (OS), progression-free survival (PFS), disease progression, and nonrelapse mortality (NRM) among Black (N=303) and White (N=1892) recipients of AHCT for MM, who were reported to the Center for International Blood and Marrow Transplant Research (CIBMTR) from 1995 to 2005. The Black cohort was more likely to be female, and had better Karnofsky performance scores, but lower hemoglobin and albumin levels at diagnosis. Black recipients were younger and more likely to be transplanted later in their disease course. Disease stage and treatment characteristics prior to AHCT were similar between the 2 groups. Black and White recipients had similar probabilities of 5-year OS (52% versus 47%, P=.19) and PFS (19% versus 21%, P=.64) as well as cumulative incidences of disease progression (72% versus 72%, P=.97) and NRM (9% versus 8%, P=.52). In multivariate analyses, race was not associated with any of these endpoints. Black recipients of AHCT for MM have similar outcomes compared to Whites, suggesting that the reasons underlying lower rates of AHCT in Blacks need to be studied further to ensure equal access to effective therapy.

Development of target-specific treatments in multiple myeloma.

In the last decade, the novel agents lenalidomide, bortezomib, and thalidomide have dramatically improved outcomes for patients with multiple myeloma (MM). A number of new therapies with precise targets involved in MM cell growth and replication are now in development and have the potential for further improvements. Second-generation proteasome inhibitors and thalidomide derivatives may offer increased efficacy and safety. Investigational therapies with rationally selected targets in MM include inhibitors of histone deacetylase, heat shock protein 90, mammalian target of rapamycin, BCL2, Akt, mitogen-activated protein kinase, and telomerase. In addition, monoclonal antibodies directed against several targets have been developed and many are showing promise in initial clinical trials in MM. Interest in the ancient remedy of arsenic trioxide has been revived because of its proapoptotic effects on mitochondria, despite its established toxicities. In general, combination regimens are proving the most efficacious, which is to be expected given the multiple overlapping pathways responsible for MM growth and progression.

Recent trends in the management of newly diagnosed multiple myeloma.

PURPOSE OF REVIEW: Many recent trials have been undertaken that incorporate novel agents into the treatment of newly diagnosed multiple myeloma patients. This review highlights the current status of different approaches to initial therapy in the era of novel drugs. RECENT FINDINGS: The therapy of newly diagnosed patients with multiple myeloma is still usually based on age and eligibility for autologous stem cell transplantation (ASCT). In older patients, several randomized trials have evaluated the addition of a novel agent to oral melphalan and prednisone, while novel agents have been incorporated before, during and after ASCT in younger individuals. Newer investigational approaches that are not age-dependent include continuous myeloma suppression with dexamethasone plus an immunomodulatory derivative, or the use of multiple cycles of combination regimens followed by a treatment break or maintenance therapy. Updated information is now also available regarding the use of nonmyeloablative allogeneic transplantation. The biologic heterogeneity of myeloma is most easily measured in the clinic by fluorescence in-situ hybridization (FISH) cytogenetics, and the detection of adverse cytogenetics is beginning to influence treatment decisions. SUMMARY: Clinical trials have established the superiority of regimens containing novel agents in the initial management of myeloma, although a number of questions remain about the optimal strategy.

An open-label, pharmacokinetic study of lenalidomide and dexamethasone therapy in previously untreated multiple myeloma (MM) patients with various degrees of renal impairment - validation of official dosing guidelines.

Lenalidomide is a backbone agent in the treatment of multiple myeloma, but dose adjustment is required for those with renal impairment (RI). We evaluated the pharmacokinetics (PK) and safety of lenalidomide and dexamethasone as frontline pre-transplant induction, with doses adjusted at start of each cycle based on creatinine clearance, as per the official dosing guidelines. After 4 cycles, PK studies showed that patients with moderate RI (30 ≤ CrCl < 60 mL/min) receiving 10 mg dosing may be under-dosed and those with severe RI (CrCl <30ml/min) appeared appropriately dosed initially, but sustained significant decreases in maximum serum concentration (Cmax) after repeated dosing, due to rapid clinical improvement and enhanced drug clearance. PK drug monitoring during cycle 1 may facilitate appropriate and timely dose adjustments. Adverse events rates did not vary based on severity of RI. No patient discontinued lenalidomide for toxicity. This supports the feasibility and safety of frontline lenalidomide in transplant-eligible patients with RI.

Drug-induced Thrombotic Microangiopathy with Concurrent Proteasome Inhibitor Use in the Treatment of Multiple Myeloma: A Case Series and Review of the Literature.

Thrombotic microangiopathy (TMA) is a life-threatening clinical syndrome characterized by hemolytic anemia, thrombocytopenia, and microvascular thrombosis, resulting in ischemia and organ damage. Multiple myeloma (MM) is a neoplasm arising from clonal plasma cells within the bone marrow. The treatment frequently includes multi-agent immunochemotherapy, often with the use of proteasome inhibitors (PIs) such as bortezomib, carfilzomib, or ixazomib. There are increasing reports of TMA in association with PI exposure. This review summarizes the epidemiology, pathogenesis, and diagnosis of PI-related drug-induced TMA. We will outline the definition and diagnosis of TMA and explore an important cause of hemolysis in patients with MM: drug-induced TMA after PI exposure, an increasingly recognized therapeutic complication. This will be emphasized through the description of 3 novel cases of TMA. These illustrative cases occurred after treatment with high-dose weekly carfilzomib, cyclophosphamide, and dexamethasone as part of the MCRN003/MYX1 phase II clinical trial (NCT02597062) in relapsed MM.