Triplet Therapy, Transplantation, and Maintenance until Progression in Myeloma.

BACKGROUND: In patients with newly diagnosed multiple myeloma, the effect of adding autologous stem-cell transplantation (ASCT) to triplet therapy (lenalidomide, bortezomib, and dexamethasone [RVD]), followed by lenalidomide maintenance therapy until disease progression, is unknown. METHODS: In this phase 3 trial, adults (18 to 65 years of age) with symptomatic myeloma received one cycle of RVD. We randomly assigned these patients, in a 1:1 ratio, to receive two additional RVD cycles plus stem-cell mobilization, followed by either five additional RVD cycles (the RVD-alone group) or high-dose melphalan plus ASCT followed by two additional RVD cycles (the transplantation group). Both groups received lenalidomide until disease progression, unacceptable side effects, or both. The primary end point was progression-free survival. RESULTS: Among 357 patients in the RVD-alone group and 365 in the transplantation group, at a median follow-up of 76.0 months, 328 events of disease progression or death occurred; the risk was 53% higher in the RVD-alone group than in the transplantation group (hazard ratio, 1.53; 95% confidence interval [CI], 1.23 to 1.91; P<0.001); median progression-free survival was 46.2 months and 67.5 months. The percentage of patients with a partial response or better was 95.0% in the RVD-alone group and 97.5% in the transplantation group (P = 0.55); 42.0% and 46.8%, respectively, had a complete response or better (P = 0.99). Treatment-related adverse events of grade 3 or higher occurred in 78.2% and 94.2%, respectively; 5-year survival was 79.2% and 80.7% (hazard ratio for death, 1.10; 95% CI, 0.73 to 1.65). CONCLUSIONS: Among adults with multiple myeloma, RVD plus ASCT was associated with longer progression-free survival than RVD alone. No overall survival benefit was observed. (Funded by the National Heart, Lung, and Blood Institute and others; DETERMINATION ClinicalTrials.gov number, NCT01208662.).

Patient-reported outcomes of multiple myeloma patients treated with panobinostat after ≥2 lines of therapy based on the international phase 3, randomized, double-blind, placebo-controlled PANORAMA-1 trial.

The phase 3 PANORAMA-1 trial led to regulatory approvals of panobinostat (PAN) in combination with bortezomib (BTZ) and dexamethasone (DEX) for the treatment of multiple myeloma after ≥2 prior regimens, including BTZ and an immunomodulatory drug. Patient-reported outcomes (PROs) were assessed in PANORAMA-1, with data available for 73 patients in the PAN + BTZ + DEX arm and 74 patients in the placebo (PBO) + BTZ + DEX arm. Per the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 (EORTC QLQ-C30), global health status/quality of life (QoL) scores initially declined with PAN + BTZ + DEX during the first 24 weeks before approaching baseline scores and remaining steady during the next 24 weeks, with no difference between arms at Week 48. The EORTC QLQ-Myeloma module (EORTC QLQ-MY20) demonstrated initial improvements and subsequent stabilization of disease symptom scores in both arms and initial worsening and subsequent improvement of side effects of treatment scores, with the initial worsening more pronounced and recovery less pronounced with PAN + BTZ + DEX. Functional Assessment of Cancer Therapy/Gynecologic Oncology Group-Neurotoxicity scores remained relatively stable and similar between the arms. Overall, these PRO findings support the addition of PAN to the BTZ+DEX regimen as an efficacious treatment option, with limited symptomatology and impact on patients' QoL. The reported results are based on a descriptive analysis of the data. No formal statistical tests have been performed.

A phase 2 study of modified lenalidomide, bortezomib and dexamethasone in transplant-ineligible multiple myeloma.

We sought a regimen that incorporates optimal novel agents and balances efficacy with toxicity in transplant-ineligible multiple myeloma (MM) patients. Our study evaluated modified lenalidomide-bortezomib-dexamethasone (RVD lite) in this population and was administered over a 35-day cycle. Lenalidomide 15 mg was given orally on days 1-21; bortezomib 1·3 mg/m2 weekly subcutaneously on days 1, 8, 15 and 22; and dexamethasone 20 mg orally was given on the day of and day after bortezomib for 9 cycles followed by 6 cycles of consolidation with lenalidomide and bortezomib. The primary objective was to evaluate the overall response rate (ORR); secondary objectives included safety, progression-free survival (PFS) and overall survival (OS). Fifty-three eligible patients were screened between April 2013 and May 2015; 50 received at least one dose of therapy. Median age at study entry was 73 years (range 65-91). The ORR was 86% and 66% of patients achieved a very good partial response or better. Median PFS was 35·1 months (95% confidence interval 30·9-not reached) and median OS was not reached at a median follow-up of 30 months. Peripheral neuropathy was reported in 31 (62%) patients with only 1 patient experiencing grade 3 symptoms. RVD lite is a well-tolerated and highly effective regimen, with robust PFS and OS, in the transplant-ineligible MM population.

Panobinostat plus bortezomib and dexamethasone in previously treated multiple myeloma: outcomes by prior treatment.

Panobinostat is a potent pan-deacetylase inhibitor that affects the growth and survival of multiple myeloma (MM) cells through alteration of epigenetic mechanisms and protein metabolism. Panobinostat plus bortezomib and dexamethasone (PAN-BTZ-Dex) led to a significant increase in progression-free survival (PFS) vs placebo plus bortezomib and dexamethasone (Pbo-BTZ-Dex) in patients with relapsed or relapsed and refractory MM in the phase 3 PANORAMA 1 trial. This subgroup analysis evaluated outcomes in patients in the PANORAMA 1 trial based on prior treatment: a prior immunomodulatory drug (IMiD; n = 485), prior bortezomib plus an IMiD (n = 193), and ≥2 prior regimens including bortezomib and an IMiD (n = 147). Median PFS with PAN-BTZ-Dex vs Pbo-BTZ-Dex across subgroups was as follows: prior IMiD (12.3 vs 7.4 months; hazard ratio [HR], 0.54; 95% confidence interval [CI], 0.43-0.68), prior bortezomib plus IMiD (10.6 vs 5.8 months; HR, 0.52; 95% CI, 0.36-0.76), and ≥2 prior regimens including bortezomib and an IMiD (12.5 vs 4.7 months; HR, 0.47; 95% CI, 0.31-0.72). Common grade 3/4 adverse events and laboratory abnormalities in patients who received PAN-BTZ-Dex across the prior treatment groups included thrombocytopenia, lymphopenia, neutropenia, diarrhea, and asthenia/fatigue. Incidence of on-treatment deaths among patients who received prior bortezomib and an IMiD (regardless of number of prior regimens) was similar between treatment arms. This analysis demonstrated a clear PFS benefit of 7.8 months with PAN-BTZ-Dex among patients who received ≥2 prior regimens including bortezomib and an IMiD, a population with limited treatment options and poorer prognosis. This trial was registered at www.clinicaltrials.gov as #NCT01023308.

Panobinostat plus bortezomib and dexamethasone: impact of dose intensity and administration frequency on safety in the PANORAMA 1 trial.

Panobinostat in combination with bortezomib and dexamethasone demonstrated a significant and clinically meaningful progression-free survival benefit compared with placebo, bortezomib and dexamethasone in the phase 3 PANORAMA 1 (Panobinostat Oral in Multiple Myeloma 1) trial. Despite this benefit, patients in the panobinostat arm experienced higher rates of adverse events (AEs) and higher rates of discontinuation due to AEs. This PANORAMA 1 subanalysis examined AEs between 2 treatment phases of the study (TP1 and TP2), in which administration frequency of bortezomib and dexamethasone differed per protocol. The incidences of several key AEs were lower in both arms following the planned reduction of bortezomib dosing frequency in TP2. In the panobinostat arm, rates of thrombocytopenia (grade 3/4: TP1, 56·7%; TP2, 6·0%), diarrhoea (grade 3/4: TP1, 24·1%; TP2, 7·1%), and fatigue (grade 3/4: TP1, 16·3%; TP2, 1·8%) were lower in TP2 compared with TP1. Dose intensity analysis of panobinostat and bortezomib by cycle in the panobinostat arm showed reductions of both agent doses during cycles 1-4 due to dose adjustments for AEs. Exposure-adjusted analysis demonstrated a reduction in thrombocytopenia frequency in TP1 following dose adjustment. These results suggest that optimization of dosing with this regimen could improve tolerability, potentially leading to improved patient outcomes.

A phase 2 trial of lenalidomide, bortezomib, and dexamethasone in patients with relapsed and relapsed/refractory myeloma.

In this prospective, multicenter, phase 2 study, 64 patients with relapsed or relapsed and refractory multiple myeloma (MM) received up to 8 21-day cycles of bortezomib 1.0 mg/m(2) (days 1, 4, 8, and 11), lenalidomide 15 mg/day (days 1-14), and dexamethasone 40/20 mg/day (cycles 1-4) and 20/10 mg/day (cycles 5-8) (days of/after bortezomib dosing). Responding patients could receive maintenance therapy. Median age was 65 years; 66% were male, 58% had relapsed and 42% had relapsed and refractory MM, and 53%, 75%, and 6% had received prior bortezomib, thalidomide, and lenalidomide, respectively. Forty-eight of 64 patients (75%; 90% confidence interval, 65-84) were alive without progressive disease at 6 months (primary end point). The rate of partial response or better was 64%; median duration of response was 8.7 months. Median progression-free and overall survivals were 9.5 and 30 months, respectively (median follow-up: 44 months). Common treatment-related toxicities included sensory neuropathy (53%), fatigue (50%), and neutropenia (42%); common grade 3/4 treatment-related toxicities included neutropenia (30%), thrombocytopenia (22%), and lymphopenia (11%). Grade 3 motor neuropathy was reported in 2 patients. Lenalidomide-bortezomib-dexamethasone appears effective and tolerable in patients with relapsed or relapsed and refractory MM, demonstrating substantial activity among patients with diverse prior therapies and adverse prognostic characteristics. This trial is registered with www.clinicaltrials.gov as #NCT00378209.

PANORAMA 2: panobinostat in combination with bortezomib and dexamethasone in patients with relapsed and bortezomib-refractory myeloma.

Panobinostat is an oral pan-deacetylase inhibitor that synergizes with bortezomib to inhibit both the aggresome and proteasome pathways in preclinical studies. PANORAMA 2 is a phase 2 trial of panobinostat in combination with bortezomib and dexamethasone to treat patients with relapsed and bortezomib-refractory multiple myeloma (with ≥2 prior lines of therapy, including an immunomodulatory drug, and patients who had progressed on or within 60 days of the last bortezomib-based therapy). Fifty-five heavily pretreated patients were enrolled (median, 4 prior regimens, including a median of 2 prior bortezomib-containing regimens). The overall response rate was 34.5% (1 near-complete response and 18 partial responses). An additional 10 patients achieved minimal response, for a clinical benefit rate of 52.7%. Median exposure and progression-free survival were 4.6 and 5.4 months, respectively. In patients who achieved a response, median time to response was 1.4 months, and median duration of response was 6.0 months. Common grade 3/4 adverse events, regardless of study drug relationship, included thrombocytopenia (63.6%), fatigue (20.0%), and diarrhea (20.0%). Only 1 patient had grade 3 peripheral neuropathy. Panobinostat, when combined with bortezomib and dexamethasone, can recapture responses in heavily pretreated, bortezomib-refractory multiple myeloma patients. This trial was registered at www.clinicaltrials.gov as #NCT01083602.

Panobinostat plus bortezomib and dexamethasone versus placebo plus bortezomib and dexamethasone in patients with relapsed or relapsed and refractory multiple myeloma: a multicentre, randomised, double-blind phase 3 trial.

BACKGROUND: Panobinostat is a potent oral pan-deacetylase inhibitor that in preclinical studies has synergistic anti-myeloma activity when combined with bortezomib and dexamethasone. We aimed to compare panobinostat, bortezomib, and dexamethasone with placebo, bortezomib, and dexamethasone in patients with relapsed or relapsed and refractory multiple myeloma. METHODS: PANORAMA1 is a multicentre, randomised, placebo-controlled, double-blind phase 3 trial of patients with relapsed or relapsed and refractory multiple myeloma who have received between one and three previous treatment regimens. Patients were randomly assigned (1:1) via an interactive web-based and voice response system, stratified by number of previous treatment lines and by previous use of bortezomib, to receive 21 day cycles of placebo or panobinostat (20 mg; on days 1, 3, 5, 8, 10, 12, orally), both in combination with bortezomib (1·3 mg/m(2) on days 1, 4, 8, 11, intravenously) and dexamethasone (20 mg on days 1, 2, 4, 5, 8, 9, 11, 12, orally). Patients, physicians, and the investigators who did the data analysis were masked to treatment allocation; crossover was not permitted. The primary endpoint was progression-free survival (in accordance with modified European Group for Blood and Marrow Transplantation criteria and based on investigators' assessment) and was analysed by intention to treat. The study is ongoing, but no longer recruiting, and is registered at ClinicalTrials.gov, number NCT01023308. FINDINGS: 768 patients were enrolled between Jan 21, 2010, and Feb 29, 2012, with 387 randomly assigned to panobinostat, bortezomib, and dexamethasone and 381 to placebo, bortezomib, and dexamethasone. Median follow-up was 6·47 months (IQR 1·81-13·47) in the panobinostat group and 5·59 months (2·14-11·30) in the placebo group. Median progression-free survival was significantly longer in the panobinostat group than in the placebo group (11·99 months [95% CI 10·33-12·94] vs 8·08 months [7·56-9·23]; hazard ratio [HR] 0·63, 95% CI 0·52-0·76; p<0·0001). Overall survival data are not yet mature, although at the time of this analysis, median overall survival was 33·64 months (95% CI 31·34-not estimable) for the panobinostat group and 30·39 months (26·87-not estimable) for the placebo group (HR 0·87, 95% CI 0·69-1·10; p=0·26). The proportion of patients achieving an overall response did not differ between treatment groups (235 [60·7%, 95% CI 55·7-65·6] for panobinostat vs 208 [54·6%, 49·4-59·7] for placebo; p=0·09); however, the proportion of patients with a complete or near complete response was significantly higher in the panobinostat group than in the placebo group (107 [27·6%, 95% CI 23·2-32·4] vs 60 [15·7%, 12·2-19·8]; p=0·00006). Minimal responses were noted in 23 (6%) patients in the panobinostat group and in 42 (11%) in the placebo group. Median duration of response (partial response or better) was 13·14 months (95% CI 11·76-14·92) in the panobinostat group and 10·87 months (9·23-11·76) in the placebo group, and median time to response (partial response or better) was 1·51 months (1·41-1·64) in the panobinostat group and 2·00 months (1·61-2·79) in the placebo group. Serious adverse events were reported in 228 (60%) of 381 patients in the panobinostat group and 157 (42%) of 377 patients in the placebo group. Common grade 3-4 laboratory abnormalities and adverse events (irrespective of association with study drug) included thrombocytopenia (256 [67%] in the panobinostat group vs 118 [31%] in the placebo group), lymphopenia (202 [53%] vs 150 [40%]), diarrhoea (97 [26%] vs 30 [8%]), asthenia or fatigue (91 [24%] vs 45 [12%]), and peripheral neuropathy (67 [18%] vs 55 [15%]). INTERPRETATION: Our results suggest that panobinostat could be a useful addition to the treatment armamentarium for patients with relapsed or relapsed and refractory multiple myeloma. Longer follow up will be necessary to determine whether there is any effect on overall survival. FUNDING: Novartis Pharmaceuticals.

Outcomes in patients with relapsed or refractory multiple myeloma in a phase I study of everolimus in combination with lenalidomide.

Everolimus, an oral mammalian target of rapamycin (mTOR) inhibitor, has been studied in multiple myeloma (MM) but lacks significant single agent activity. Based on preclinical studies showing synergistic activity of mTOR inhibitors with lenalidomide, we studied the combination of lenalidomide and everolimus in relapsed or refractory MM in a phase I clinical trial. We assessed patient samples using gene expression, Western blotting and immunohistochemistry to probe the mTOR pathway. Twenty-six patients were evaluable for toxicity. Dose-limiting toxicities included grade 4 neutropenia and thrombocytopenia. The maximum tolerated dose was lenalidomide 15 mg and everolimus 5 mg for 21 d with a 7 d rest period. Grade 3/4 adverse events included thrombocytopenia (35%) and neutropenia (42%). The overall response rate was 65% (1 complete response + 4 partial response + 10 minimal response). The median progression-free survival was 5·5 months and median overall survival was 29·5 months. Biomarker data demonstrated downregulation of phosphorylated p70S6K. Gene expression profiling suggested activation of mTOR in responders versus non-responders. The combination of lenalidomide and everolimus was well tolerated with predictable toxicities and showed responses in a heavily pretreated population. When confirmed with larger patient numbers, this analysis may guide patient selection for future clinical trials of mTOR inhibition in MM.

Proliferative glomerulonephritis with monoclonal immunoglobulin deposits in a kidney allograft.

Paraprotein may accumulate in glomeruli and cause kidney damage associated with variable histopathologic patterns and a characteristic immunofluorescence staining restricted to a single light chain and/or a single heavy chain isotype. Hence, such glomerular injury includes diseases caused by deposition of a monoclonal light chain, heavy chain, or entire immunoglobulin (light and heavy chains), which may manifest as proliferative glomerulonephritis. In this report, we focus on the latter as the least characterized of the 3, particularly in the transplantation setting. We describe a case of late transplant dysfunction associated with glomerular immunoglobulin G1/κ deposits. We also present our experience with proliferative glomerulonephritis and monoclonal immunoglobulin deposits in transplant and native kidney biopsies, with reference to the literature.

Compartment-Specific Bioluminescence Imaging platform for the high-throughput evaluation of antitumor immune function.

Conventional assays evaluating antitumor activity of immune effector cells have limitations that preclude their high-throughput application. We adapted the recently developed Compartment-Specific Bioluminescence Imaging (CS-BLI) technique to perform high-throughput quantification of innate antitumor activity and to show how pharmacologic agents (eg, lenalidomide, pomalidomide, bortezomib, and dexamethasone) and autologous BM stromal cells modulate that activity. CS-BLI-based screening allowed us to identify agents that enhance or inhibit innate antitumor cytotoxicity. Specifically, we identified compounds that stimulate immune effector cells against some tumor targets but suppressed their activity against other tumor cells. CS-BLI offers rapid, simplified, and specific evaluation of multiple conditions, including drug treatments and/or cocultures with stromal cells and highlights that immunomodulatory pharmacologic responses can be heterogeneous across different types of tumor cells. This study provides a framework to identify novel immunomodulatory agents and to prioritize compounds for clinical development on the basis of their effect on antitumor immunity.

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.

Lenalidomide, bortezomib, and dexamethasone combination therapy in patients with newly diagnosed multiple myeloma.

This phase 1/2 study is the first prospective evaluation of lenalidomide-bortezomib-dexamethasone in front-line myeloma. Patients (N = 66) received 3-week cycles (n = 8) of bortezomib 1.0 or 1.3 mg/m(2) (days 1, 4, 8, 11), lenalidomide 15 to 25 mg (days 1-14), and dexamethasone 40 or 20 mg (days 1, 2, 4, 5, 8, 9, 11, 12). Responding patients proceeded to maintenance or transplantation. Phase 2 dosing was determined to be bortezomib 1.3 mg/m(2), lenalidomide 25 mg, and dexamethasone 20 mg. Most common toxicities included sensory neuropathy (80%) and fatigue (64%), with only 27%/2% and 32%/3% grade 2/3, respectively. In addition, 32% reported neuropathic pain (11%/3%, grade 2/3). Grade 3/4 hematologic toxicities included lymphopenia (14%), neutropenia (9%), and thrombocytopenia (6%). Thrombosis was rare (6% overall), and no treatment-related mortality was observed. Rate of partial response was 100% in both the phase 2 population and overall, with 74% and 67% each achieving very good partial response or better. Twenty-eight patients (42%) proceeded to undergo transplantation. With median follow-up of 21 months, estimated 18-month progression-free and overall survival for the combination treatment with/without transplantation were 75% and 97%, respectively. Lenalidomide-bortezomib-dexamethasone demonstrates favorable tolerability and is highly effective in the treatment of newly diagnosed myeloma. This study is registered at http://clinicaltrials.gov as NCT00378105.

The Medical Research Council Myeloma IX trial: the impact on treatment paradigms.

Osteolytic bone disease is a hallmark of symptomatic multiple myeloma. Bisphosphonates have been the mainstay of treatment to preserve skeletal integrity and prevent skeletal-related events in patients with myeloma-related bone disease. Recently, the MRC Myeloma IX trial demonstrated for the first time improved survival and delayed disease progression with the use of an intravenous amino-bisphosphonate, zoledronic acid, vs. an oral agent, clodronate, with intensive and non-intensive anti-myeloma treatment regimens in patients with newly diagnosed multiple myeloma. These results validate a large body of preclinical, translational and other clinical data suggesting anti-myeloma effects of amino-bisphosphonates. In addition, this trial also provided the first head-to-head evidence for superiority of one bisphosphonate over another (zoledronic acid vs. clodronate) for reducing skeletal morbidity in patients with multiple myeloma, as well as a prospective comparison of toxicities. Despite the use of non-bortezomib containing anti-myeloma treatment regimens in the MRC Myeloma IX trial, these results are encouraging and provide an impetus to continue to evaluate current treatment guidelines for myeloma-associated bone disease.

The potential benefits of participating in early-phase clinical trials in multiple myeloma: long-term remission in a patient with relapsed multiple myeloma treated with 90 cycles of lenalidomide and bortezomib.

We present the case of a woman with relapsed multiple myeloma (MM) who received combination lenalidomide and bortezomib therapy for 90 cycles followed by continuous lenalidomide monotherapy and has completed over 100 cycles of treatment to date. The patient was diagnosed with advanced-stage, symptomatic MM in 2001. Following a partial response (PR) to dexamethasone in combination with pamidronate and thalidomide, the patient underwent protocol-directed non-myeloablative allogeneic bone marrow transplantation from her matched sibling donor the following year. In 2004, the patient relapsed and was enrolled in a phase I, dose-escalation trial of lenalidomide plus bortezomib for relapsed and refractory MM. After eight cycles of study treatment, the patient achieved a minimal response. The patient received a total of 90 cycles of treatment with lenalidomide 5 mg given for 14 d every 21 d, and 1 mg/m(2) of bortezomib initially given on days 1, 4, 8, and 11 for the first 20 cycles, and then weekly thereafter on days 1 and 8. Bortezomib was discontinued after 90 cycles, and the patient continued to receive lenalidomide monotherapy. As of cycle 100, the patient achieved a PR. Currently, she is clinically stable with response sustained for over 7 yrs. Therapy has been well tolerated with no significant long-term toxicity; no dose reductions of lenalidomide and bortezomib were required. The excellent tolerability of this steroid-free approach and the durable response seen underscore the potential benefits of participating in early-phase clinical trials evaluating novel therapies and new drug combinations. This case further supports that combination treatment with lenalidomide and bortezomib is an effective therapy in the management of patients with relapsed and refractory MM.

Management of relapsed and relapsed/refractory multiple myeloma.

Despite significant progress in the treatment of multiple myeloma (MM) over the past decade, this disease remains incurable and almost all patients ultimately experience relapse and become refractory to treatment over time. However, the outlook for patients with relapsed MM has improved markedly with the use of the immunomodulatory drugs thalidomide and lenalidomide, and the proteasome inhibitor bortezomib. Moreover, the development of new drug classes based on preclinical rationale and the introduction of next-generation agents is likely to further expand treatment options and improve outcomes for relapsed MM.

A phase I safety study of enzastaurin plus bortezomib in the treatment of relapsed or refractory multiple myeloma.

The purpose of this study was to assess the safety and identify the recommended doses of enzastaurin and bortezomib in combination for future Phase II studies in patients with relapsed or refractory multiple myeloma. Three dose levels (DLs) of oral enzastaurin and intravenous bortezomib were used according to a conventional "3 + 3" design. A loading dose of enzastaurin (250 mg twice/day [BID]) on Day 1 was followed by enzastaurin 125 mg BID for 1 week, after which bortezomib was added (Cycle 1, 28 days, 1.0 mg/m(2) : Days 8, 11, 15, and 18; seven subsequent 21-day cycles, 1.3 mg/m(2) : Days 1, 4, 8, and 11). Twenty-three patients received treatment; all patients received prior systemic therapy. Most patients received ≥3 regimens; 17 patients were bortezomib-refractory. A median of four treatment cycles (range 1-24) was completed. No dose-limiting toxicities were observed; thus, DL 3 was the recommended Phase II dose. The most common drug-related Grade 3/4 toxicities were thrombocytopenia (n = 6) and anemia (n = 2). No patients died on therapy. One patient (DL 1) achieved a very good partial response; three patients (DLs 2 and 3), a partial response; nine patients, stable disease; and four patients, progressive disease. The recommended Phase II doses in patients with relapsed or refractory multiple myeloma are as follows: enzastaurin loading dose of 375 mg three times/day on Day 1 followed by 250 mg BID, with bortezomib 1.3 mg/m(2) on Days 1, 4, 8, and 11 of a 21-day cycle. The combination was well-tolerated and demonstrated some antimyeloma activity.

Functional Genomics Identify Distinct and Overlapping Genes Mediating Resistance to Different Classes of Heterobifunctional Degraders of Oncoproteins.

Heterobifunctional proteolysis-targeting chimeric compounds leverage the activity of E3 ligases to induce degradation of target oncoproteins and exhibit potent preclinical antitumor activity. To dissect the mechanisms regulating tumor cell sensitivity to different classes of pharmacological "degraders" of oncoproteins, we performed genome-scale CRISPR-Cas9-based gene editing studies. We observed that myeloma cell resistance to degraders of different targets (BET bromodomain proteins, CDK9) and operating through CRBN (degronimids) or VHL is primarily mediated by prevention of, rather than adaptation to, breakdown of the target oncoprotein; and this involves loss of function of the cognate E3 ligase or interactors/regulators of the respective cullin-RING ligase (CRL) complex. The substantial gene-level differences for resistance mechanisms to CRBN- versus VHL-based degraders explains mechanistically the lack of cross-resistance with sequential administration of these two degrader classes. Development of degraders leveraging more diverse E3 ligases/CRLs may facilitate sequential/alternating versus combined uses of these agents toward potentially delaying or preventing resistance.

Tailoring treatment for multiple myeloma patients with relapsed and refractory disease.

Responses to treatment of relapsed and refractory multiple myeloma are characteristically short, and median survival is as brief as 6 months. Although prognostic factors in the context of relapsed and refractory disease require further characterization, high-risk patients include those with certain cytogenetic abnormalities, high beta2-microglobulin, and low serum albumin. The development of novel therapies targeting disease biology and tumor microenvironment has significantly improved the outlook for patients with relapsed and refractory disease, with bortezomib (Velcade), a first-in-class proteasome inhibitor, and the immunomodulatory agents thalidomide (Thalomid) and lenalidomide (Revlimid) constituting "backbone"agents in this setting. More recent approaches for treating relapsed and refractory myeloma that are recommended by the National Comprehensive Cancer Network include single-agent bortezomib, single-agent lenalidomide, bortezomib/dexamethasone, bortezomib plus pegylated liposomal doxorubicin, lenalidomide/dexamethasone, and lenalidomide/bortezomib/dexamethasone. Individualized treatment of progressive myeloma should take into account the time to progression and/or the type of prior therapy. Additional clinical challenges discussed in this article are renal dysfunction, extramedullary disease, and advanced bone disease. Finally, participation in clinical trials is especially encouraged in this patient population.

Targeting histone deacetylase 3 (HDAC3) in the bone marrow microenvironment inhibits multiple myeloma proliferation by modulating exosomes and IL-6 trans-signaling.

Multiple myeloma (MM) is an incurable cancer that derives pro-survival/proliferative signals from the bone marrow (BM) niche. Novel agents targeting not only cancer cells, but also the BM-niche have shown the greatest activity in MM. Histone deacetylases (HDACs) are therapeutic targets in MM and we previously showed that HDAC3 inhibition decreases MM proliferation both alone and in co-culture with bone marrow stromal cells (BMSC). In this study, we investigate the effects of HDAC3 targeting in BMSCs. Using both BMSC lines as well as patient-derived BMSCs, we show that HDAC3 expression in BMSCs can be induced by co-culture with MM cells. Knock-out (KO), knock-down (KD), and pharmacologic inhibition of HDAC3 in BMSCs results in decreased MM cell proliferation; including in autologous cultures of patient MM cells with BMSCs. We identified both quantitative and qualitative changes in exosomes and exosomal miRNA, as well as inhibition of IL-6 trans-signaling, as molecular mechanisms mediating anti-MM activity. Furthermore, we show that HDAC3-KD in BM endothelial cells decreases neoangiogenesis, consistent with a broad effect of HDAC3 targeting in the BM-niche. Our results therefore support the clinical development of HDAC3 inhibitors based not only on their direct anti-MM effects, but also their modulation of the BM microenvironment.