Current drug therapy for multiple myeloma

Targeting complete response with upfront bortezomib consolidation versus observation after the achievement of complete response following autologous transplantation for multiple myeloma (TUBA study)

Complete response (CR) after treatment for multiple myeloma is associated with superior progression-free survival (PFS). Multiple myeloma patients were prospectively recruited for induction treatment with bortezomib and dexamethasone (BD) followed by autologous hematopoietic cell transplantation (auto-HCT) between 2010 and 2012. If patients did not achieve CR after auto-HCT, BD consolidation therapy was added to target CR. After the BD induction phase (n = 46), greater than or equal to CR was achieved in 4 patients (8%). After auto-HCT (n = 34), greater than or equal to CR was achieved in 9 patients (20%) and very good partial response (VGPR) was achieved in 11 (24%). Of the 24 patients who received auto-HCT and whose response was less than CR, 21 received BD consolidation therapy for a median of 4 courses. Finally, the maximum response with or without BD consolidation was greater than or equal to CR in 19 (41%), VGPR in 7 (15%), and PR in 6 (13%). Through BD consolidation, CR was achieved in 8 of 11 patients with post-HCT VGPR and in 2 of 12 patients with post-HCT PR. In total, 4 year PFS and overall survival were 43 and 80%, respectively. After adjusting for clinical factors, there was no difference in PFS between CR patients after auto-HCT and BD consolidation, while patients with less than or equal to VGPR after consolidation had a significantly lower PFS. Patients with post-HCT CR showed good PFS, and targeting CR through BD consolidation could improve the CR rate. It would be worthwhile to prospectively compare the efficacy of consolidation only for patients who failed to achieve CR to a universal consolidation strategy.

Phase I trial of vorinostat combined with bortezomib for the treatment of relapsing and/or refractory multiple myeloma

Preclinical studies have shown that targeted combination therapy consisting of vorinostat and bortezomib has antitumor activity in multiple myeloma (MM). We examined this drug combination in advanced relapsing and/or refractory MM patients (n = 34). Although the maximum tolerated dose was not reached, the study found this combination regimen generally well tolerated and clinically active in relapsed and/or refractory MM patients.

BACKGROUND

Development of targeted therapies for MM has improved response rates and increased patient survival, but ultimately the disease becomes refractory and progresses. Vorinostat combined with bortezomib has demonstrated synergistic antiproliferative and proapoptotic activity in preclinical models of MM. The objectives of this study were to determine the maximum tolerated dose for vorinostat with bortezomib in patients with advanced MM and to evaluate the clinical benefit of this new drug combination.

PATIENTS AND METHODS

Patients ≥ 18 years old with relapsed and/or refractory MM were enrolled into escalating dose cohorts of vorinostat and bortezomib combination therapy. Thirty-four patients were enrolled and were evaluable for safety and efficacy analyses.

RESULTS

All patients reported adverse events, 89% of which were mild to moderate in severity. Thirteen patients experienced 29 serious adverse events, 12 (41%) of which were considered drug-related. The maximum tolerated dose was not reached. Partial responses were observed in 9 (27%) patients. Minimal responses were observed in 2 additional patients (6%), and another 20 patients (59%) experienced disease stabilization.

CONCLUSION

Vorinostat with bortezomib is generally well-tolerated and has clinical activity in patients with relapsed and/or refractory MM. Response rates were similar in patients previously exposed to bortezomib and patients who were naive to bortezomib therapy.

Phase I trial of lenalidomide and CCI-779 in patients with relapsed multiple myeloma: evidence for lenalidomide-CCI-779 interaction via P-glycoprotein

PURPOSE

Multiple myeloma (MM) is an incurable plasma-cell neoplasm for which most treatments involve a therapeutic agent combined with dexamethasone. The preclinical combination of lenalidomide with the mTOR inhibitor CCI-779 has displayed synergy in vitro and represents a novel combination in MM.

PATIENTS AND METHODS

A phase I clinical trial was initiated for patients with relapsed myeloma with administration of oral lenalidomide on days 1 to 21 and CCI-779 intravenously once per week during a 28-day cycle. Pharmacokinetic data for both agents were obtained, and in vitro transport and uptake studies were conducted to evaluate potential drug-drug interactions.

RESULTS

Twenty-one patients were treated with 15 to 25 mg lenalidomide and 15 to 20 mg CCI-779. The maximum-tolerated dose (MTD) was determined to be 25 mg lenalidomide with 15 mg CCI-779. Pharmacokinetic analysis indicated increased doses of CCI-779 resulted in statistically significant changes in clearance, maximum concentrations, and areas under the concentration-time curves, with constant doses of lenalidomide. Similar and significant changes for CCI-779 pharmacokinetics were also observed with increased lenalidomide doses. Detailed mechanistic interrogation of this pharmacokinetic interaction demonstrated that lenalidomide was an ABCB1 (P-glycoprotein [P-gp]) substrate.

CONCLUSION

The MTD of this combination regimen was 25 mg lenalidomide with 15 mg CCI-779, with toxicities of fatigue, neutropenia, and electrolyte wasting. Pharmacokinetic and clinical interactions between lenalidomide and CCI-779 seemed to occur, with in vitro data indicating lenalidomide was an ABCB1 (P-gp) substrate. To our knowledge, this is the first report of a clinically significant P-gp-based drug-drug interaction with lenalidomide.

Phase I and II pharmacokinetic and pharmacodynamic study of the proteasome inhibitor bortezomib in Japanese patients with relapsed or refractory multiple myeloma

The purpose of this phase I and II study was to evaluate the safety, pharmacokinetics, pharmacodynamics, and efficacy of bortezomib in Japanese patients with relapsed or refractory multiple myeloma. This was a dose-escalation study designed to determine the recommended dose for Japanese patients (phase I) and to investigate the antitumor activity and safety (phase II) of bortezomib administered on days 1, 4, 8, and 11 every 21 days. Thirty-four patients were enrolled. A dose-limiting toxicity was febrile neutropenia, which occurred in one of six patients in the highest-dose cohort in phase I and led to the selection of 1.3 mg/m(2) as the recommended dose. Adverse events >or= grade 3 were rare except for hematological toxicities, although there was one fatal case of interstitial lung disease. The overall response rate was 30% (95% confidence interval, 16-49%). Pharmacokinetic evaluation showed a biexponential decline, characterized by a rapid distribution followed by a longer elimination, after dose administration, whereas the area under the concentration-time curve increased proportionately with the dose. Bortezomib was effective in Japanese patients with relapsed or refractory multiple myeloma. A favorable tolerability profile was also seen, although the potential for pulmonary toxicity should be monitored closely. The pharmacokinetic and pharmacodynamic profiles of bortezomib in the present study warrant further investigations, including more relevant administration schedules.

Experimental Study Enhancing the Chemosensitivity of Multiple Myeloma to Melphalan by Using a Tissue-Specific APE1-Silencing RNA Expression Vector

PURPOSE

Because of a developing resistance to chemotherapy agents, multiple myeloma (MM) has been an incurable disease until now. As a means to overcome MM tumor cell resistance and/or sensitize tumor cells to chemotherapeutic treatments currently used, we examined the role of human apurinic/apyrimidinic endonuclease 1 (APE1) in resistance and prognosis in patients with MM.

PATIENTS AND METHODS

Multiple myeloma cells were analyzed by using bone marrow specimens from 32 patients with MM and 10 normal volunteers.

RESULTS

The positive rate of APE1 protein expression was 65.6% in the bone marrow specimens of patients with MM with known clinical outcome. Positive rate of APE1 expression beyond grade 2 in the relapsed/refractory group was significantly higher than that in the untreated group. No positive results of grade > 2 were detected in bone marrow specimens from patients with noncancerous disease. It was also confirmed that the amount of APE1 protein in KM3 cells was positively correlated with the dose and action time of melphalan. Because APE1 was overexpressed in refractory/relapsed MM cells, siRNA-targeted technology was used to decrease APE1 levels in KM3 cells, with protein levels deceasing to 80%-90% within 24 hours and continuing to decease for 72 hours. The best dose and time of inhibiting expression of APE1 protein were 3 mug and 2 days long. A decrease in APE1 levels in siRNA-treated KM3 cells led to enhanced cell sensitization to melphalan.

CONCLUSION

The findings herein present prognostic and therapeutic implications for treating relapsed/refractory MM. The APE1-silencing RNA results demonstrate the feasibility of the therapeutic modulation of APE1 using a variety of molecules and approaches.

166Ho-DOTMP plus melphalan followed by peripheral blood stem cell transplantation in patients with multiple myeloma: results of two phase 1/2 trials

Holmium-166 1, 4, 7, 10-tetraazcyclododecane-1, 4, 7, 10-tetramethylenephosphonate (166Ho-DOTMP) is a radiotherapeutic that localizes specifically to the skeleton and can deliver high-dose radiation to the bone and bone marrow. In patients with multiple myeloma undergoing autologous hematopoietic stem cell transplantation two phase 1/2 dose-escalation studies of high-dose 166Ho-DOTMP plus melphalan were conducted. Patients received a 30 mCi (1.110 Gbq) tracer dose of 166Ho-DOTMP to assess skeletal uptake and to calculate a patient-specific therapeutic dose to deliver a nominal radiation dose of 20, 30, or 40 Gy to the bone marrow. A total of 83 patients received a therapeutic dose of 166Ho-DOTMP followed by autologous hematopoietic stem cell transplantation 6 to 10 days later. Of the patients, 81 had rapid and sustained hematologic recovery, and 2 died from infection before day 60. No grades 3 to 4 nonhematologic toxicities were reported within the first 60 days. There were 27 patients who experienced grades 2 to 3 hemorrhagic cystitis, only 1 of whom had received continuous bladder irrigation. There were 7 patients who experienced complications considered to be caused by severe thrombotic microangiopathy (TMA). No cases of severe TMA were reported in patients receiving in 166Ho-DOMTP doses lower than 30 Gy. Approximately 30% of patients experienced grades 2 to 4 renal toxicity, usually at doses targeting more than 40 Gy to the bone marrow. Complete remission was achieved in 29 (35%) of evaluable patients. With a minimum follow-up of 23 months, the median survival had not been reached and the median event-free survival was 22 months. 166Ho-DOTMP is a promising therapy for patients with multiple myeloma and merits further evaluation.

Dosimetry of high dose skeletal targeted radiotherapy (STR) with 166Ho-DOTMP

A study was undertaken to determine the maximum tolerated dose of (166)Ho-DOTMP that could be administered safely, without negatively impacting marrow re-engraftment, in patients with multiple myeloma treated with melphalan prior to transplant. Ho-166 DOTMP is a tetraphosphonate that localizes rapidly to bone surface. The Ho-166 physical half-life is 26.8 hr and the maximum beta energy is 1.8 MeV. Standard dosimetry models were adapted for radiation absorbed dose estimates using data obtained from whole body counting of the low abundance photons emitted by (166)Ho. Eighty-three patients received high dose (166)Ho-DOTMP followed by melphalan and transplant of peripheral blood stem cells. Twenty-five patients also received 8 Gy total body radiation (TBI). Dosages administered ranged from 460 to 4476 mCi (166)Ho-DOTMP. Marrow dose was derived using the assumption that all radioactivity not excreted by 20 hours was localized to the bone surfaces, and applying the Eckerman bone and marrow dose model to the calculated bone residence times. The dosimetry of the urinary bladder and kidneys was important because of the rapid excretion of the non-targeted radioactivity via the urinary pathway. The dynamic bladder model was used for bladder wall surface dose, and the ICRP 53 kinetic model was used to model kidney kinetics with an additional blood component included. Marrow doses ranged from 13 to 59 Gy and successful hematapoietic recovery occurred. Bladder doses ranged from 4.7 to 157 Gy. Hemorrhagic cystitis occurred in some patients who received more than 40 Gy to the bladder wall surface. Bladder irrigation was successful in protecting patients from bladder toxicity. Kidney doses ranged from 0.5-7.9 Gy. Kidney toxicity in the form of thrombotic microangiopathy with renal dysfunction was observed, with the severity being related to Ho-166-DOTMP radiation dose and probably the dose rate as well. In a future trial, kidney dosimetry will be assessed using early serial gamma camera imaging and modifications will be implemented to reduce renal toxicity.

Oxaliplatin (L-OHP) treatment of human myeloma cells induces in vitro growth inhibition and apoptotic cell death

Oxaliplatin (L-OHP), a diaminocyclohexane platinum derivative, is an active and well tolerated anticancer drug which is presently used in the treatment of gastrointestinal tumours. Since the efficacy of L-OHP in the treatment of multiple myeloma (MM) has not yet been evaluated, we studied the antiproliferative activity of this compound in vitro in a panel of MM cell lines (XG1, XG1a, U266 and IM-9). We found that L-OHP inhibited the growth of MM cells at therapeutically achievable concentrations (IC(50): 5-10 microM after 24 h of exposure) and was more active than Cisplatin (CDDP) or Carboplatin (CBDCA). The activity of L-OHP was apparently not affected by interleukin-6 (IL-6), the major growth and survival factor of MM cells. We also found that L-OHP induced apoptotic cell death. We demonstrated that the combination of L-OHP with Dexamethasone (Dex) resulted in the enhancement of the anti-myeloma effects. L-OHP and Dex both induced poly adenosine diphosphate (ADP)-ribose polymerase (PARP) cleavage and this induction was enhanced by the combined treatment. L-OHP-induced apoptosis correlated with caspase-3 cleavage, but this correlation could not be demonstrated in Dex-treated cells. Taken together, these in vitro results provide a rationale for the experimental use of L-OHP in the treatment of MM patients and suggest therapeutic combinations of potential value.

IgM Myeloma: An IgM Gammopathy Distinct from Waldenstrom's Macroglobulinemia

A 65-year-old patient with an IgM gammopathy, plasma cell infiltration of the bone marrow, lytic lesions of the skeleton, and symptoms of hyperviscosity was evaluated. A diagnosis of IgM myeloma was made. Treatment for multiple myeloma was initiated and resulted in a significant clinical response. There is ongoing debate whether IgM myeloma exists as a unique entity, oras a variant of Waldenstrom's macroglobulinemia. We reviewed the English literature and discovered only six cases documented as IgM multiple myeloma. Further investigation revealed 30 reported cases, which had characteristics typical of an IgM myeloma, but were documented as variations of B-cell neoplastic disease. We acknowledge IgM myeloma to be an entity distinct from Waldenstrom's macroglobulinemia. It is characterized by an IgM monoclonal gammopathy, a predominance of plasma cells infiltrating the bone marrow, and typically associated with osteolytic lesions and/or osteoporosis. Recognizing IgM myeloma is necessary for appropriate disease management.

[Multiple medullary and extramedullary plasmacytomas in an HIV infected female patient]

INTRODUCTION

Before the HIV infection era, plasmocyte tumor rarely occurred in patients younger than 40 years of age. Less frequent than lymphomas, the incidence of these blood diseases has however substantially increased in HIV-infected patients. In these patients, in addition to onset at earlier age, their clinical presentation is quite different and extramedullary plasmocytomas in unexpected locations are more common.

EXEGESIS

We report the case of a 29-year-old HIV-infected female patient in whom were diagnosed occipital, parotidal, sphenoidal, epidural, and uterine plasmocytomas for which chemotherapy and subsequent radiotherapy were successful. The increase in the incidence of plasmocyte tumors in HIV-infected patients might be facilitated by Epstein Barr Virus (EBV) co-infection, HIV-related chronic antigenic stimulation, and secretion of interleukin 6 by infected lymphocytes.

CONCLUSION

Plasmocyte tumors belong to neoplasia whose incidence is increased in HIV infection. Their currently poor diagnosis should be improved by highly active antiretroviral therapies allowing enhanced chemotherapy with possibility of autograft.