Genomic landscape of patients in a phase II study of zanubrutinib in ibrutinib- and/or acalabrutinib-intolerant patients with B-cell malignancies

Not available.

Elranatamab in relapsed or refractory multiple myeloma: the MagnetisMM-1 phase 1 trial

Multiple myeloma (MM) is a plasma cell malignancy expressing B cell maturation antigen (BCMA). Elranatamab, a bispecific antibody, engages BCMA on MM and CD3 on T cells. The MagnetisMM-1 trial evaluated its safety, pharmacokinetics and efficacy. Primary endpoints, including the incidence of dose-limiting toxicities as well as objective response rate (ORR) and duration of response (DOR), were met. Secondary efficacy endpoints included progression-free survival (PFS) and overall survival (OS). Eighty-eight patients with relapsed or refractory MM received elranatamab monotherapy, and 55 patients received elranatamab at efficacious doses. Patients had received a median of five prior regimens; 90.9% were triple-class refractory, 29.1% had high cytogenetic risk and 23.6% received prior BCMA-directed therapy. No dose-limiting toxicities were observed during dose escalation. Adverse events included cytopenias and cytokine release syndrome. Exposure was dose proportional. With a median follow-up of 12.0 months, the ORR was 63.6% and 38.2% of patients achieving complete response or better. For responders, the median DOR was 17.1 months. All 13 patients evaluable for minimal residual disease achieved negativity. Even after prior BCMA-directed therapy, 53.8% achieved response. For all 55 patients, median PFS was 11.8 months, and median OS was 21.2 months. Elranatamab achieved durable responses, manageable safety and promising survival for patients with MM. ClinicalTrials.gov Identifier: NCT03269136 .

A phase II multi-arm study of magrolimab combinations in patients with relapsed/refractory multiple myeloma

Magrolimab is a monoclonal antibody that blocks CD47, a 'do not eat me' signal overexpressed on tumor cells. CD47 is overexpressed in multiple myeloma (MM), which contributes to its pathogenesis. Preclinical studies have shown that CD47 blockade induces macrophage activation, resulting in elimination of myeloma cells, and that there is synergy between magrolimab and certain anticancer therapies. These findings suggest that magrolimab-based combinations may have a therapeutic benefit in MM. This phase II study investigates magrolimab in combination with commonly used myeloma therapies in patients with relapsed/refractory MM and includes a safety run-in phase followed by a dose-expansion phase. Primary end points include the incidence of dose-limiting toxicities and adverse events (safety run-in) and the objective response rate (dose expansion).

Zanubrutinib in patients with previously treated B-cell malignancies intolerant of previous Bruton tyrosine kinase inhibitors in the USA: a phase 2, open-label, single-arm study

BACKGROUND

We hypothesised that zanubrutinib, a highly selective next-generation Bruton tyrosine kinase (BTK) inhibitor, would be a safe and active treatment for patients intolerant of ibrutinib, acalabrutinib, or both. We aimed to assess whether zanubrutinib would prolong treatment duration by minimising treatment-related toxicities and discontinuations in patients with previously treated B-cell malignancies.

METHODS

This ongoing, phase 2, multicentre, open-label, single-arm study was done in 20 centres in the USA. Patients aged 18 or older with previously treated B-cell malignancies (chronic lymphocytic leukaemia, small lymphocytic lymphoma, mantle cell lymphoma, Waldenström macroglobulinaemia, or marginal zone lymphoma) who became intolerant of ibrutinib, acalabrutinib, or both, were orally administered zanubrutinib 160 mg twice daily or 320 mg once daily per investigator. The primary endpoint was recurrence and change in severity of ibrutinib or acalabrutinib intolerance events based on investigator-assessed adverse events. Secondary endpoints were investigator-assessed overall response rate; duration of response; disease control rate; and progression-free survival. Analyses included all patients who received any dose of the study drug. This study is registered with ClinicalTrials.gov, NCT04116437.

FINDINGS

Between Oct 14, 2019, and Sept 8, 2021, 67 patients (36 [54%] men and 31 [46%] women) who were intolerant of ibrutinib (n=57; cohort 1) or of acalabrutinib or acalabrutinib and ibrutinib (n=10; cohort 2) were enrolled. 63 (94%) patients were White, one (2%) had multiple ethnicities, and three (5%) had unreported or unknown ethnicity. Most intolerance events (81 [70%] of 115 for ibrutinib; 15 [83%] of 18 for acalabrutinib) did not recur with zanubrutinib. Of the recurring events, seven (21%) of 34 ibrutinib intolerance events and two (67%) of three acalabrutinib intolerance events recurred at the same severity with zanubrutinib; 27 (79%) ibrutinib intolerance events and one (33%) acalabrutinib intolerance event recurred at a lower severity with zanubrutinib. No events recurred at higher severity. No grade 4 intolerance events recurred. 64 (96%) of 67 patients had one or more adverse events with zanubrutinib; the most common adverse events were contusion (in 15 [22%] of 67 patients), fatigue (14 [21%]), myalgia (ten [15%]), arthralgia (nine [13%]), and diarrhoea (nine [13%]). Atrial fibrillation occurred in three (4%) patients (all grade 2). Eight (12%) of 67 patients had serious adverse events (anaemia, atrial fibrillation, bronchitis, COVID-19, COVID-19 pneumonia, febrile neutropenia, salmonella gastroenteritis, transfusion reaction, trigeminal nerve disorder, and urinary tract infection). No treatment-related deaths occurred. The median follow-up time was 12·0 months (IQR 8·2-15·6). Among the 64 efficacy-evaluable patients, disease control rate was 93·8% (60; 95% CI 84·8-98·3) and overall response rate was 64·1% (41; 95% CI 51·1-75·7). The median duration of response was not reached; the 12-month event-free duration of response rate was 95·0% (95% CI 69·5-99·3). Similarly, median progression-free survival was not reached; 18-month progression-free survival was 83·8% (95% CI 62·6-93·6).

INTERPRETATION

Patients intolerant of previous BTK inhibitors have limited treatment options. These results suggest that zanubrutinib, a safe and viable treatment for patients with B-cell malignancies, might fill that unmet need for those who exhibit intolerance to ibrutinib or acalabrutinib.

FUNDING

BeiGene.

A phase 2, multicentre, open-label trial (ACE-LY-003) of acalabrutinib in patients with relapsed or refractory marginal zone lymphoma

Acalabrutinib, a Bruton tyrosine kinase inhibitor, demonstrated greater selectivity and improved safety versus ibrutinib in a head-to-head trial in relapsed/refractory (R/R) chronic lymphocytic leukaemia. In the R/R marginal zone lymphoma (MZL) cohort (phase 2) of a phase 1b/2 trial (NCT02180711), 43 patients with MZL and at least one prior therapy received acalabrutinib 100 mg twice daily until disease progression or unacceptable toxicity [median age 69 years (range 42-84); median one (1-4) prior systemic regimens]. Median follow-up was 13.3 months (range 0.5-45.5). Among 40 patients evaluable for response, investigator-assessed overall response rate was 53% [95% confidence interval (CI) 36%-69%] with five (13%) complete responses. Tumour reduction occurred in 40 (93%) of the treated patients. Median time to response was 2.9 months (median duration of response not estimable). Estimated median progression-free survival (PFS) was 27.4 months (12-month PFS rate, 67%). Five patients died (disease progression, n = 4; septic shock, n = 1). Seventeen patients (40%) had grade 3 or higher adverse events (AEs), most commonly neutropenia (14%), anaemia, dyspnoea (7% each), fatigue and thrombocytopenia (5% each). Hypertension occurred in 5%; atrial fibrillation/flutter and major haemorrhage were not reported. AEs led to treatment discontinuation in three (7%) patients. Acalabrutinib was active and well tolerated in patients with R/R MZL.

Elranatamab, a BCMA-targeted T-cell redirecting immunotherapy, for patients with relapsed or refractory multiple myeloma: Updated results from MagnetisMM-1

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Background: Elranatamab (PF-06863135) is a bispecific molecule that activates and redirects the T-cell mediated immune response against multiple myeloma (MM), a plasma cell dyscrasia characterized by expression of B-cell maturation antigen (BCMA). MagnetisMM-1 (NCT03269136), the ongoing Phase 1 first-in-human study for elranatamab, was designed to characterize safety, pharmacokinetics (PK), pharmacodynamics, and efficacy for patients (pts) with relapsed or refractory MM. Methods: Elranatamab was given subcutaneously (SC) at doses from 80 to 1000µg/kg either weekly or every 2 weeks (Q2W). Treatment-emergent adverse events (TEAEs) were graded by Common Terminology Criteria for Adverse Events (v4.03) and cytokine release syndrome (CRS) by American Society for Transplantation and Cellular Therapy criteria. PK, cytokine and soluble BCMA profiling, and lymphocyte subset analyses were performed. Response was assessed by International Myeloma Working Group (IMWG) criteria. Minimal residual disease (MRD) was assessed by next generation sequencing at a sensitivity of 1×10-5 in accordance with IMWG criteria. Results: A total of 55 pts received single-agent elranatamab SC at a dose ≥215μg/kg as of 1-Nov-2021. Median age was 64 (range 42-80) years, and 27% of pts were Black/African American or Asian. Median number of prior regimens was 6 (range 2-15), 91% were triple-class refractory, 56% had prior stem cell transplantation, 27% had high cytogenetic risk, and 22% received prior BCMA-targeted therapy. The most common TEAEs regardless of causality included CRS, neutropenia, anemia, injection site reaction, and lymphopenia. With pre-medication and a single priming dose (600µg/kg or 44mg), the overall incidence of CRS at the recommended dose (1000µg/kg or 76mg) was 67% and limited to Grade 1 (33%) or Grade 2 (33%), with no events Grade 3 or higher. Exposure was dose dependent and Q2W dosing achieved exposure associated with anti-myeloma efficacy. Cytokine increases occurred with the first dose and were reduced by pre-medication. Soluble BCMA decreased with disease response, elranatamab therapy was associated with increased peripheral T cell proliferation, and median time to response was 36 days (range 7-73). With a median follow-up of 8.1 months (range 0.3-21) and including only IMWG confirmed responses, 31% of pts achieved complete response or better and the overall response rate was 64% (95% CI 50-75%). For responders (n = 35), median duration of response was not yet reached, but the probability of being event-free at 6 months was 91% (95% CI 73-97%). Single-agent elranatamab induces durable clinical and molecular responses, and updated data including MRD assessment will be presented. Conclusions: Elranatamab shows a manageable safety profile and achieves durable clinical and molecular responses for pts with relapsed or refractory MM. Clinical trial information: NCT03269136.

Efficacy and safety of elranatamab (PF-06863135), a B-cell maturation antigen (BCMA)-CD3 bispecific antibody, in patients with relapsed or refractory multiple myeloma (MM)

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Background: Elranatamab (PF-06863135) is a humanized bispecific monoclonal antibody (IgG2a) that targets BCMA, a member of the tumor necrosis factor receptor superfamily expressed in MM, and CD3 on T cells. We reported results for intravenous (IV) dosing (Raje et al. Blood. 2019;134(S1):1869) and now update for subcutaneous (SC) dosing from the ongoing Phase 1 study (MagnetisMM-1). Methods: Patients (pts) received elranatamab at 80, 130, 215, 360, 600, and 1000μg/kg SC weekly. A modified toxicity probability interval method was used for escalation, with monitoring for dose-limiting toxicity (DLT) to end of the first cycle. Treatment-emergent adverse events (TEAEs) were graded by Common Terminology Criteria for Adverse Events (v4.03), and cytokine release syndrome (CRS) by American Society for Transplantation and Cellular Therapy criteria (Lee et al. Biol Blood Marrow Transplant. 2019;25:625). Response was assessed by International Myeloma Working Group criteria. Pharmacokinetics, cytokine profiling, and T cell immunophenotyping were performed. Results: 30 pts had received elranatamab as of 4-Aug-2020 at 80 (n = 6), 130 (n = 4), 215 (n = 4), 360 (n = 4), 600 (n = 6), or 1000 (n = 6) μg/kg SC weekly. Pts had a median of 8 prior treatments; 87% had triple refractory disease, 97% had prior anti-CD38 therapy, and 23% had prior BCMA-directed antibody drug conjugate or chimeric antigen receptor T cell therapy. The most common all causality TEAEs included lymphopenia (n = 24, 80%; 20% G3, 60% G4), CRS (n = 22, 73%; none > G2), anemia (n = 17, 57%; 43% G3, 3% G4), injection site reaction (n = 16, 53%; none > G2), thrombocytopenia (n = 16, 53%; 23% G3, 17% G4), and neutropenia (n = 12, 40%; 17% G3, 17% G4). Both CRS and immune effector cell-associated neurotoxicity syndrome (n = 6, 20%) were limited to ≤G2 with median durations of 2 and 1.5 days, respectively. No DLT was observed. Exposure increased with dose, and Tmax ranged from 3–7 days. Cytokine increases occurred with the first dose, and increased T-cell proliferation was observed in peripheral blood. The overall response rate (ORR) for doses ≥215μg/kg was 75% (n = 15/20) including partial response (PR; n = 6), very good PR (VGPR; n = 3), complete response (CR; n = 1), and stringent CR (sCR; n = 5). Median time to response was 22 days, and 3 of 4 pts (75%) with prior BCMA-directed therapy achieved response (VGPR, n = 2 and sCR, n = 1). Updated data, including duration of response, will be presented. Conclusions: Elranatamab demonstrated a manageable safety profile, and SC doses ≥215μg/kg achieved ORR of 75% with CR/sCR rate of 30%. These results demonstrate the safety and efficacy of SC elranatamab in this relapsed/refractory population and support ongoing development of elranatamab for pts with MM, both as monotherapy and in combination with standard or novel therapies. Clinical trial information: NCT03269136.

Preliminary results of the phase 2 study of zanubrutinib in patients with previously treated B-cell malignancies intolerant to ibrutinib and/or acalabrutinib

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Background: Many patients (pts) with B-cell malignancies require continuous treatment with Bruton tyrosine kinase inhibitors (BTKi). Adverse events (AEs) are a common reason for ibrutinib (ibr) or acalabrutinib (acala) discontinuation. Early data from BGB-3111-215 showed zanubrutinib (zanu) was well tolerated in pts with B-cell malignancies intolerant to ibr or acala. We report preliminary results with a median follow-up of 4.2 mo. Methods: Pts meeting protocol criteria for intolerance to ibr, acala or both (without documented progressive disease) were given zanu monotherapy (160 mg twice daily or 320 mg once daily). Recurrence of AEs that led to intolerance of prior BTKi and additional safety measures were assessed based on the Common Terminology Criteria for AEs v5.0. Investigators determined responses using disease status at study entry as baseline. Results: As of November 1, 2020 (cutoff), 44 pts (n=34 chronic lymphocytic leukemia/small lymphocytic lymphoma, n=6 Waldenström macroglobulinemia, n=2 mantle cell lymphoma, n=2 marginal zone lymphoma) were enrolled, received ≥1 dose of zanu, and analyzed for safety. Median age was 70.5 y (range, 49-91); median duration of treatment was 4.2 mo (range, 0.1-12.6). Median number of prior regimens was 2 (range, 1-12). Regarding prior BTKi, 39 pts received ibr only, 4 received ibr and acala, and 1 received acala only. The median number of ibr- or acala-intolerant AEs per pt was 2 (range, 1-5). 83% of ibr and 78% of acala intolerant events did not reccur on zanu; Table. At data cutoff, 43 pts remained on treatment; 1 withdrew consent due to zanu-unrelated grade 3 syncope. Overall, 34 pts (77.3%) reported any AE; most commonly reported AEs were myalgia (n=9; 20.5%), contusion (n=8; 18.2%), dizziness (n=7; 15.9%), fatigue (n=7; 15.9%), and cough (n=5; 11.4%). Grade ≥3 AEs were reported in 6 pts (13.6%), serious AEs in 1 pt (2.3%, febrile neutropenia and salmonella infection), AEs requiring dose interruptions in 6 pts (13.6%), and AEs leading to dose reduction in 2 pts (4.5%). No AEs led to zanu discontinuation. No deaths were reported. All efficacy evaluable pts (26/26 [100%]) maintained (10 [38.5%]) or achieved deepening (16 [61.5%]) of their response. Conclusions: Zanu provides an additional treatment option after intolerance to other BTKi, demonstrating tolerability and sustained or improved efficacy. Updated results will be presented. Recurrence and Severity Change of AEs Leading to Ibr or Acala Intolerance. Clinical trial information: NCT04116437. [Table: see text]

Health care cost impact associated with adverse events (AEs) among treatments in third-line+ (3L+) relapsed/refractory follicular lymphoma (R/R FL)

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Background: Tazemetostat, a first-in-class oral, selective methyltransferase inhibitor of enhancer of zeste homolog 2 (EZH2) activity, was approved by the US Food and Drug Administration for treatment of patients with R/R FL after demonstrating single-agent antitumor activity in patients with wild-type or mutant EZH2. Phosphoinositide 3-kinase inhibitors (PI3Kis; idelalisib, duvelisib, and copanlisib) are also indicated for 3L+ R/R FL, but these drugs are associated with serious toxicities, such as neutropenia, infection, and immune-mediated toxicities. A matching-adjusted indirect comparison (MAIC) of tazemetostat with these 3 PI3Kis was previously presented in 3L+ R/R FL, showing that tazemetostat is associated with more favorable safety, and similar efficacy compared to each of the PI3Kis. The objective of this study was to estimate the difference in AE-related health care costs for each treatment. Methods: AE-related costs were sourced from a study of costs in patients hospitalized with AEs, using oncology-specific data when available. Matching-adjusted AE incidence was multiplied by costs related to each AE. Grade ≥3 AEs with incidence ≥5% for any of the evaluated treatments were included. Cost differences were estimated per treatment episode, based on duration of exposure in the tazemetostat clinical trial (9.3 months for tazemetostat, <7 months for the 3 comparators). Incidence rates were then converted to a monthly basis using an exponential curve. Results: The PI3Kis are estimated to incur $13,534 to $18,737 higher AE-related management costs per episode compared with tazemetostat. Adjusting for duration of exposure, each of the PI3Kis is project to cost $2,563 to $3,820 more per month than tazemetostat in AE-related costs. These estimates indicate that the AE-related cost impact of PI3Kis compared with tazemetostat is 3.4- to 6.1-fold higher on a per-episode basis, and 5.0- to 10.4-fold higher on a monthly basis. Conclusions: Quantifying the AE cost impact of tazemetostat based on AE incidence rates estimated by MAIC analysis adjusts for population differences and allows for more direct cost savings comparisons when accounting for duration of exposure to different treatments. Patients with 3L+ R/R FL who are treated with tazemetostat are estimated to incur substantially lower AE-related costs compared with PI3Kis (idelalisib, duvelisib, and copanlisib). [Table: see text]

Salvage transplantation for allograft failure using fludarabine and alemtuzumab as conditioning regimen

Graft failure after allogeneic blood or marrow transplantation, although generally uncommon, can be a devastating complication. This report includes the outcome of nine patients who received a salvage transplant for failure to engraft after one (n=8) or 2 (n=1) prior transplants. Eight patients received allografts from the original donor. All received fludarabine 30 mg/m(2) i.v. and alemtuzumab 20 mg i.v. daily from days -6 to -2. Daily CYA was begun on day -2, and the allograft was infused on day 0. The therapy was well tolerated with low toxicity, and all nine patients engrafted, recovering neutrophils at a median of 12 days after transplant. Four patients died: two of relapse, one of a fungal infection in the setting of GVHD and one of multiple sclerosis. The combination of fludarabine and alemtuzumab is an effective and well-tolerated salvage conditioning regimen for patients who experience graft failure after blood or marrow transplants.

The allogeneic effect revisited: exogenous help for endogenous, tumor-specific T cells

The "allogeneic effect" refers to the induction of host B cell antibody synthesis or host T cell cytotoxicity, including tumoricidal activity, by an infusion of allogeneic lymphocytes. We show that treatment of mice with cyclophosphamide (Cy) followed by CD8(+) T cell-depleted allogeneic donor lymphocyte infusion (Cy + CD8(-) DLI) induces regression of established tumors with minimal toxicity in models of both hematologic and solid cancers, even though the donor cells are eventually rejected by the host immune system. The optimal antitumor effect of Cy + CD8(-) DLI required the presence of donor CD4(+) T cells, host CD8(+) T cells, and alloantigen expression by normal host but not tumor tissue. The results support a model in which a donor CD4(+) T cell-mediated graft-versus-host (GVH) reaction effectively awakens antitumor immunity among Cy-resistant host CD8(+) T cells. These events provide the cellular mechanism of the "allogeneic effect" in antitumor immunity. Cy + CD8(-) DLI may be an effective and minimally toxic strategy for awakening the host immune response to advanced cancers.

Characterization of plasmid DNA transfer into mouse skeletal muscle: evaluation of uptake mechanism, expression and secretion of gene products into blood

The expression of naked plasmid DNA coding for firefly luciferase (pRSVluc) or a secreted protein, human-alpha-1-antitrypsin (pRcCMVhAAT) in mouse skeletal muscle was characterized following administration by an improved intramuscular injection technique. Injection guided by intense illumination along the longitudinal axis of the mouse quadriceps muscle and parallel to the myofibers yielded 200-fold higher levels of luciferase expression than perpendicular injection. Luciferase expression was inhibited by an excess of non-coding DNA or dextran sulfate suggesting that muscle DNA uptake mechanism(s) can be saturated. Injected plasmid DNA was rapidly eliminated from the muscle as evidenced by tissue distribution studies of radiolabeled hAAT plasmid and Southern analysis. However, PCR analysis demonstrated that hAAT cDNA persisted in the muscle for at least 1 month after injection. Immunohistochemistry techniques indicated that the hAAT gene was expressed by the muscle fibers. ELISA analysis of serum samples collected from intramuscularly injected mice demonstrated that secreted hAAT protein concentration peaked in serum by day 7, started to decline by day 14 and was barely detectable 21 days post-injection. RT-PCR analysis demonstrated that hAAT transcript persisted at the site of injection for at least 1 month indicating that the decline of serum hAAT concentration 21 days post-injection was not due to the absence of hAAT transcript. However, the decline of hAAT protein concentration in the serum was inversely correlated with accumulation of murine anti-hAAT antibodies in circulation.

Intratracheal gene delivery to the mouse airway: characterization of plasmid DNA expression and pharmacokinetics

Intratracheal administration of plasmid DNA resulted in gene expression in mouse airways in the absence of any enhancing agent. Administration of plasmid DNA encoding the chloramphenicol acetyltransferase gene (CAT) in sterile water lead to CAT transgene expression that peaked between 1 and 3 days and was detected up to 28 days after DNA administration. Transgene expression was independent of mouse gender, age and strain. Levels of expression from DNA in various isotonic solutions did not differ from levels obtained with DNA administered in water, suggesting that transfection is not dependent on damage to airway cells caused by a hypo-osmotic delivery vehicle. Pharmacokinetic studies using radiolabeled plasmid DNA showed that DNA was rapidly degraded, while higher levels of radioactivity were retained for longer duration following administration of cationic liposome-DNA complexes in the airway. Southern blot and PCR analysis confirmed that DNA complexed with DOTMA-DOPE was retained in the airways for a longer period. However, cationic liposomes DOTMA-DOPE (1:1) or DOTAP complexed with DNA, did not enhance expression over DNA alone. These results suggest that 'naked' plasmid DNA should be included as a control in all studies on intratracheal gene delivery using nonviral systems.

Efficacy evaluation of a novel submicron miconazole emulsion in a murine cryptococcosis model

Submicron emulsions of miconazole were stabilized by using a combination of three emulsifiers comprising phospholipids, poloxamer, and deoxycholic acid (DCA). The presence of DCA was vital for prolonged emulsion stability owing to its contribution to the elevated zeta potential of the emulsion. Further, the results by the phospholipid surface labelling colorimetric technique clearly suggested that poloxamer molecules interacted with phospholipid polar-head groups of the mixed DCA-phospholipid interfacial film, resulting in the stabilization of the emulsion by a steric enthalpic entropic mechanism. The plain emulsion vehicle was well tolerated up to a dose of 0.6 ml injected i.v. to BALB/c mice. The maximum tolerated dose of miconazole was 80 and 250 mg/kg in Daktarin i.v. (a marketed product) and emulsion, respectively, showing an improved safety ratio of 1 to 3 in favor of the emulsion. These results tended to confirm that the adverse effects associated with Daktarin i.v. injection should be associated with the vehicle rather than with the miconazole itself. In a murine cryptococcosis model, only one mouse out of ten remained alive by day 15 in the infected group treated with Daktarin i.v., while in the miconazole emulsion treated group, mice began to die from day 16 up to day 25 post inoculation. Thus, the multiple-dose treatment with the miconazole emulsions improved the protection offered to the infected mice. However, the therapeutic levels of miconazole that were reached in the target organ (brain) were lower than those required for complete eradication of Cryptococcus neoformans, which is known to multiply preferentially in the brain.

Characterization of diazepam submicron emulsion interface: role of oleic acid

Oleic acid markedly improved the physical stability of a diazepam submicron emulsion. The zeta potential of the emulsion increased with increased oleic acid concentration. This effect suggested that adjustment of the diazepam submicron emulsion pH to 7.8-8.0 led to the ionization of oleic acid molecules at the oil/water (o/w) interface without being excluded from the surface regions of the oil droplets. TEM freeze-fracturing examination revealed that a mixed-emulsifier monolayer film was established at the o/w interface of the submicron emulsion. No liquid crystal or liposome formation was detected. This was confirmed by the results of phosphatidylethanolamine surface labelling at the o/w interface of the emulsion. The improved stability properties conferred to the emulsion by oleic acid should be attributed not only to the zeta potential increase, but also to the strengthening of the molecular interactions occurring between phospholipid and poloxamer emulsifiers in the presence of an ionized form of oleic acid at the o/w interface of the emulsified oily droplets as evidenced in independent monolayer studies.

Submicron emulsions as colloidal drug carriers for intravenous administration: comprehensive physicochemical characterization

Submicron injectable emulsions have been gaining more and more attention in the last few years, mainly as a vehicle for the intravenous administration of lipophilic drugs rather than as an improved delivery system for drug targeting. Submicron emulsions are available, clinically well accepted, and successfully marketed. Novel original emulsion formulations are being extensively investigated and already exhibit improved pharmacological activity; this fact underlines the promising therapeutic properties of these colloidal drug carriers as vehicles for potent lipophilic drugs. It is therefore essential to carry out a comprehensive physicochemical characterization of these submicron emulsions. It is the objective of the present review to emphasize the need for physicochemical studies in the design of new submicron emulsion drug delivery systems and to describe the different approaches available for carrying out such a complete examination of the emulsion colloidal drug carrier system.

Efficacy evaluation of a novel submicron amphotericin B emulsion in murine candidiasis

A submicron amphotericin B (AmB) sterile emulsion with a mean droplet size of approximately 100 nm was prepared. The emulsion was stable at 4 degrees C over a period of 4 months. The acute toxicity results showed that the maximum tolerated dose of the AmB emulsion was 2.0 mg kg-1 as compared to 0.5 mg kg-1 for a commercial deoxycholate suspension, Fungizone. Efficacy evaluations of submicron AmB emulsion compared to Fungizone were performed in a murine candidiasis model using either a single or a multiple daily dose administration of 0.4 mg kg-1. Survival (100%) was observed up to 15-18 days post-infection in mice treated with AmB emulsion or Fungizone, while all control non-treated animals had died after 9 days in both single and multi-treatment experiments. Survival (50%) was obtained after 35 days in the single treatment, and 40 days in the multi-treatment, experiment with AmB emulsion, while treatment with Fungizone gave 50% survival after 15 and 20 days, respectively. The overall results indicate that in murine candidiasis, treatment with AmB submicron emulsion was more effective than Fungizone, suggesting a potential therapeutic application.

Short- and long-term stability assessment of a new injectable diazepam submicron emulsion

An innovative diazepam injectable emulsion, recently characterized, was submitted to short- and long-term stability studies. The initial pH of the diazepam emulsion decreased progressively with time. However, this pH decrease can be controlled by adjusting the initial pH of the emulsion. At initial adjusted pH of 7.4 or 8.0, the pH decrease of the emulsions was markedly diminished as confirmed by pH follow-up over 10 months storage. All the emulsions prepared using less than 25% oily phase remained stable at the various storage temperatures over a 10 month period. However, emulsion stability was highly dependent on the non-ionic emulsifier concentration, while both low and high phospholipid concentrations reduced emulsion stability. Furthermore, the diazepam remained intact in the emulsion, as confirmed by HPLC when stored at 4 degrees and 25 degrees C over a 16-month storage period. The optimal emulsion formulation was stable to conventional steam sterilization cycles. Exposure of the emulsion to mechanical stress conditions did not affect the integrity of the emulsion, indicating that the dosage form developed remained practically stable.

Side-effect evaluation of a new diazepam formulation: venous sequela reduction following intravenous (i.v.) injection of a diazepam emulsion in rabbits

Diazepam has been incorporated into a stable, submicronized injectable emulsion. Venous sequela induction in rabbits following iv administration of diazepam in a marketed hydroalcoholic solution and in the emulsion were determined and compared over a 5-day period. There was a marked difference in the local reactions induced by the iv administration of the marketed diazepam hydroalcoholic solution and the diazepam emulsion, even on the first postinjection day. This difference was confirmed by pathological analysis. The highest mean venous sequela score was reached by the rabbit group injected with the marketed diazepam solution. It should be noted that no statistical difference was observed between the saline and the diazepam emulsion rabbit groups during the 5 days of the observation period. The moderate increase in the venous sequela score values compared to that for the saline solution should be attributed to the intrinsic effect produced by diazepam itself, and not to the emulsion vehicle, which was shown not to induce any vascular reaction in the present study.