Stability of Melphalan in 0.9% Sodium Chloride Solutions Prepared in Polyvinyl Chloride Bags for Intravenous Injection

Efficacy of a prolonged stability melphalan formulation for intra-arterial treatment of retinoblastoma

BACKGROUND

Melphalan, which is poorly soluble at room temperature, is widely used for the treatment of retinoblastoma by selective ophthalmic artery infusion. Evomela, a propylene glycol-free formulation of melphalan with improved solubility and stability, has recently been used as an alternative.To compare the safety and efficacy of Evomela with standard-formulation melphalan (SFM) in the treatment of retinoblastoma by selective ophthalmic artery infusion.

METHODS

We performed a retrospective case-control study of patients with retinoblastoma undergoing selective ophthalmic artery infusion with SFM or Evomela at a single institution. Cycle-specific percent tumor regression (CSPTR) was estimated by comparing photos obtained during pretreatment examination under anesthesia (EUA) with those obtained during post-treatment EUA 3-4 weeks later. CSPTR, ocular salvage rates, complication rates, operation times (unadjusted and adjusted for difficulty of ophthalmic artery catheterization), and intraprocedural dose expiration rates were compared between Evomela- and SFM-treated groups. Univariate and multivariate analyses were performed.

RESULTS

Ninety-seven operations (melphalan: 45; Evomela: 52) for 23 patients with 27 retinoblastomas were studied. The ocular salvage rate was 79% in the SFM-treated group and 69% in the Evomela-treated group. Multivariate regression controlling for tumor grade, patient age, and treatment history revealed no significant differences in ocular salvage rate, CSPTR, complication rates, or operation times. Although the dose expiration rate was higher for the SFM-treated group, the difference was not statistically significant. Notably, there were no ocular or cerebral ischemic complications.

CONCLUSION

Evomela has non-inferior safety and efficacy relative to SFM when used for the treatment of retinoblastoma by selective ophthalmic artery infusion.

Challenges associated with test dose pharmacokinetic predictions of high dose melphalan exposure in patients with multiple myeloma

Aim

To evaluate the accuracy of melphalan test dose pharmacokinetic (PK) predictions of the subsequent high dose (HDM) area under the concentration-versus-time curve (AUC) and to identify sources of prediction error (PE).

Methods

A prospective multicentre PK study was conducted in 40 myeloma patients of median age 60 (range:35–71) years using a 20 mg/m² test dose administered 1–3 days prior to HDM (predominantly 180 mg/m²). PK data were collected post the test and high doses to compare predicted versus actual AUCs determined using the trapezoidal rule. Test and high dose infusion concentration, volume and duration and the time from preparation to infusion were compared using the paired Wilcoxin rank sign test. The impact of Melphalan administration parameters on PE was evaluated using the Mann–Whitney test. The predictive capacity of a previously published population PK (PopPK) model was also examined.

Results

Predicted HDM AUC was within 15% of the observed values in only 63% of patients when analysed using the trapezoidal rule and 70% of patients using PopPK. Test dose infusion concentration, volume, duration and time from preparation to infusion were significantly lower than for HDM (p < 0.005). Test dose administration within 15 min of reconstitution (n = 5) was associated with significantly lower PE than administration times of 16–60 min (n = 22), p < 0.05. Test and HDM infusion concentrations were lower in patients with large PE (> ± 15%), but the differences were not significant (p = 0.078, 0.228, respectively).

Conclusion

Test dose PK has the potential to predict subsequent HDM exposure to achieve a target AUC once melphalan administration parameters are optimised to account for stability issues in the formulation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00228-022-03396-x.

Intravitreal melphalan hydrochloride vs propylene glycol-free melphalan for retinoblastoma vitreous seeds: Efficacy, toxicity and stability in rabbits models and patients

The use of intravitreal chemotherapy has revolutionized the treatment of advanced intraocular retinoblastoma, as intravitreal melphalan has enabled difficult-to-treat vitreous tumor seeds to be controlled, leading to many more eyes being saved. However, melphalan hydrochloride (MH) degrades rapidly in solution, increasing logistical complexity with respect to time between medication preparation and administration for intravitreal administration under anesthesia for retinoblastoma. A new propylene glycol-free melphalan (PGFM) formulation has greater stability and could therefore improve access and adoption of intravitreal chemotherapy, allowing more children to retain their eye(s). We compared the efficacy and toxicity of both formulations, using our rabbit xenograft model and clinical patient experience. Three weekly 12.5 μg intravitreal injections of MH or PGFM (right eye), and saline (left eye), were administered to immunosuppressed rabbits harboring human WERI-Rb1 vitreous seed xenografts. Residual live cells were quantified directly, and viability determined by TUNEL staining. Vitreous seeds were reduced 91% by PGFM (p = 0.009), and 88% by MH (p = 0.004; PGFM vs. MH: p = 0.68). All residual cells were TUNEL-positive (non-viable). In separate experiments to assess toxicity, three weekly 12.5 μg injections of MH, PGFM, or saline were administered to non-tumor-bearing rabbits. Serial electroretinography, optical coherence tomography (OCT) and OCT-angiography were performed. PGFM and MH both caused equivalent reductions in electroretinography amplitudes, and loss of retinal microvasculature on OCT-angiography. The pattern of retinal degeneration observed on histopathology suggested that segmental retinal toxicity associated with all melphalan formulations was due to a vitreous concentration gradient-effect. Efficacy and toxicity were assessed for PGFM given immediately (within 1 h of reconstitution) vs. 4 h after reconstitution. Immediate- and delayed-administration of PGFM showed equivalent efficacy and toxicity. In addition, we evaluated efficacy and toxicity in patients (205 eyes) with retinoblastoma vitreous seeds, who were treated with a total of 833 intravitreal injections of either MH or PGFM as standard of care. Of these, we analyzed 118 MH and 131 PGFM monotherapy injections in whom serial ERG measurements were available to model retinal toxicity. Both MH and PGFM caused reductions in electroretinography amplitudes, but with no statistical difference between formulations. Comparing those patient eyes treated exclusively with PGFM versus those treated exclusively with MH, efficacy for tumor control and globe salvage was equivalent (PGFM vs. MH: 96.2% vs. 93.8%, p = 0.56), but PGFM-treated eyes received fewer injections than MH-treated eyes (average 3.2 ± 1.9 vs. 6.4 ± 2.1 injections, p < 0.0001). Taken together, these rabbit experiments and our clinical experience in retinoblastoma patients demonstrate that MH and PGFM have equivalent efficacy and toxicity. PGFM was more stable, with no decreased efficacy or increased toxicity even 4 h after reconstitution. We therefore now use PGFM over traditional MH for our patients for intravitreal treatment of retinoblastoma.

Development of a method for clinical pharmacokinetic testing to allow for targeted Melphalan dosing in multiple myeloma patients undergoing autologous transplant

AIMS

High dose melphalan (HDM) and autologous stem cell transplant (ASCT) is standard of care for multiple myeloma (MM), but there is significant variability in melphalan exposure (area under the plasma drug concentration-time curve, AUC) when using body surface area-based dosing. Our aim was to establish a method of pharmacokinetic (PK) testing for real-time melphalan dose adjustments.

METHODS

We performed a prospective PK study of melphalan 140 or 200 mg/m2 in MM patients undergoing ASCT. Twenty MM patients were administered HDM on days -2 and - 1, with PK sampling at 8-10 time points. PK testing was performed on day -2 in all patients, and on day -1 in 5 patients.

RESULTS

Less than 20% interpatient variation in the day -2 and - 1 AUC was observed. The day -2 range in AUC (4.95-11.28 mg h/L) confirmed significant interpatient variability. The hypothetical total dose ranged from 133-302 mg/m2 to achieve the total median AUC. A 4-time point AUC (0, 30, 150 and 240 min) highly correlated with the AUC from the 8-time point schedule. A higher AUC correlated with increased risk of febrile neutropenia (P = .05).

CONCLUSION

Here we outline the methods to establish novel melphalan dosing using PK testing in MM patients undergoing ASCT to target a desired melphalan AUC.

Local and Recurrent Regional Metastases of Melanoma

Up to 10% of patients with cutaneous melanoma will develop recurrent locoregional disease. While surgical resection remains the mainstay of treatment for isolated recurrences, locoregional melanoma can often present as bulky, unresectable disease and can pose a significant therapeutic challenge. This chapter focuses on the natural history of local and regionally recurrent metastases and the multiple treatment modalities which exist for advanced locoregional melanoma, including regional perfusion procedures such as hyperthermic isolated limb perfusion and isolated limb infusion, intralesional therapies, and neo-adjuvant systemic therapy strategies for borderline resectable regional disease. Hyperthermic limb perfusion (HILP) and isolated limb infusion (ILI) are generally well-tolerated and have shown overall response rates between 44% and 90%. Intralesional therapies also appear to be well-tolerated as adverse events are usually limited to the site of injection and minor transient flu-like symptoms. Systemic targeted therapies have shown to have response rates up to 85% when used as neoadjuvant therapy in patients with borderline resectable disease. While combination immunotherapy in the neoadjuvant setting has also shown promising results, this data has not yet matured.

Safety and efficacy of propylene glycol-free melphalan as conditioning in patients with AL amyloidosis undergoing stem cell transplantation

High-dose melphalan is the standard conditioning regimen for patients with AL amyloidosis receiving autologous stem cell transplantation. Conventional formulations require propylene glycol (PG) as a co-solvent and melphalan has limited solubility and chemical stability after reconstitution, with potential risks for propylene glycol-related complications. Captisol-stabilized propylene glycol-free (PG-free) melphalan has been developed with improved solubility and chemical stability. We compared a cohort of patients with AL amyloidosis receiving PG melphalan (n = 96) to those receiving PG-free melphalan (n = 48) as conditioning for autologous stem cell transplantation. Median time to neutrophil and platelet engraftment was the same; 14 days PG melphalan vs 14 days PG-free melphalan, p = 0.73 and 16 days PG melphalan vs 16 days PG-free melphalan, p = 0.52, respectively. Hospitalization rate was similar in both cohorts, 68% PG melphalan vs 58% PG-free melphalan, p = 0.27. All-cause mortality at 100 days was not statistically significant, 3% PG melphalan vs 2% PG-free melphalan, p > 0.99. Overall response rate (ORR) and rates of complete response (CR) were similar (ORR 93% PG melphalan vs 94% PG-free melphalan, p > 0.99 and CR 39% PG melphalan vs 32% PG-free melphalan, p = 0.46). PG-free melphalan showed a comparable safety and efficacy profile to PG melphalan in patients with AL amyloidosis receiving stem cell transplantation.

Solution stability of Captisol-stabilized melphalan (Evomela) versus Propylene glycol-based melphalan hydrochloride injection

PURPOSE

The objective of this study was to compare the stability of recently approved Captisol-stabilized propylene glycol-free melphalan injection (Evomela™) against currently marketed propylene glycol-based melphalan injection. The products were compared as reconstituted solutions in vials as well as admixture solutions prepared from normal saline in infusion bags.

METHODS

Evomela and propylene glycol-based melphalan injection were reconstituted in normal saline and organic custom diluent, respectively, according to their package insert instructions. The reconstituted solutions were diluted in normal saline to obtain drug admixture solutions at specific drug concentrations. Stability of the solutions was studied at room temperature by assay of melphalan and determination of melphalan-related impurities.

RESULTS

Results show that based on the increase in total impurities in propylene glycol-based melphalan injection at 0.45 mg/mL, Evomela admixture solutions are about 5, 9, 15 and 29 times more stable at concentrations of 0.45, 1.0, 2.0 and 5.0 mg/mL, respectively. Results confirmed that reconstituted Evomela solution can be stored in the vial for up to 1 h at RT or for up to 24 h at refrigerated temperature (2-8 °C) with no significant degradation. After storage in the vial, it remains stable for an additional 3-29 h after preparation of admixture solution in infusion bags at concentrations of 0.25-5.0 mg/mL, respectively. In addition, Evomela solution in saline, at concentration of 5.0 mg/mL melphalan was bacteriostatic through 72 h storage at 2-8 °C.

CONCLUSION

Formulation of melphalan with Captisol technology significantly improved stability compared to melphalan hydrochloride reconstituted with propylene-glycol based diluents.