Disease characteristics, effectiveness, and safety of vestronidase alfa for the treatment of patients with mucopolysaccharidosis VII in a novel, longitudinal, multicenter disease monitoring program.

BACKGROUND: Mucopolysaccharidosis VII (MPS VII) is an ultra-rare, autosomal recessive, debilitating, progressive lysosomal storage disease caused by reduced activity of ß-glucuronidase (GUS) enzyme. Vestronidase alfa (recombinant human GUS) intravenous enzyme replacement therapy is an approved treatment for patients with MPS VII. METHODS: This disease monitoring program (DMP) is an ongoing, multicenter observational study collecting standardized real-world data from patients with MPS VII (N ≈ 50 planned) treated with vestronidase alfa or any other management approach. Data are monitored and recorded in compliance with Good Clinical Practice guidelines and planned interim analyses of captured data are performed annually. Here we summarize the safety and efficacy outcomes as of 17 November 2022. RESULTS: As of the data cutoff date, 35 patients were enrolled: 28 in the Treated Group and seven in the Untreated Group. Mean (SD) age at MPS VII diagnosis was 4.5 (4.0) years (range, 0.0 to 12.4 years), and mean (SD) age at DMP enrollment was 13.9 (11.1) years (range, 1.5 to 50.2 years). Ten patients (29%) had a history of nonimmune hydrops fetalis. In the 23 patients who initiated treatment prior to DMP enrollment, substantial changes in mean excretion from initial baseline to DMP enrollment were observed for the three urinary glycosaminoglycans (uGAGs): dermatan sulfate (DS), -84%; chondroitin sulfate (CS), -55%; heparan sulfate (HS), -42%. Also in this group, mean reduction from initial baseline to months 6, 12, and 24 were maintained for uGAG DS (-84%, -87%, -89%, respectively), CS (-70%, -71%, -76%, respectively), and HS (+ 3%, -32%, and - 41%, respectively). All adverse events (AEs) were consistent with the known vestronidase alfa safety profile. No patients discontinued vestronidase alfa. One patient died. CONCLUSIONS: To date, the DMP has collected invaluable MPS VII disease characteristic data. The benefit-risk profile of vestronidase alfa remains unchanged and favorable for its use in the treatment of pediatric and adult patients with MPS VII. Reductions in DS and CS uGAG demonstrate effectiveness of vestronidase alfa to Month 24. Enrollment is ongoing.

Long-term Burosumab Administration Is Safe and Effective in Adults With X-linked Hypophosphatemia.

CONTEXT: Burosumab was developed as a treatment option for patients with the rare, lifelong, chronically debilitating, genetic bone disease X-linked hypophosphatemia (XLH). OBJECTIVE: Collect additional information on the safety, immunogenicity, and clinical response to long-term administration of burosumab. METHODS: UX023-CL203 (NCT02312687) was a Phase 2b, open-label, single-arm, long-term extension study of adult subjects with XLH who participated in KRN23-INT-001 or KRN23-INT-002 studies. The long-term UX023-CL203 study (January 5, 2015 through November 30, 2018) provided data up to 184 weeks. Participants in UX023-CL203 received burosumab based on the last dose in the prior KRN23-INT-001 or KRN23-INT-002 studies (0.3, 0.6, or 1.0 mg/kg given by subcutaneous injection every 4 weeks). At Week 12, burosumab could be titrated upward/downward to achieve fasting serum phosphate levels within the normal range. Primary objectives included long-term safety, the proportion of subjects achieving fasting serum phosphate in the normal range, changes in bone turnover markers, patient-reported outcomes for pain and stiffness, and measures of mobility. RESULTS: Fasting serum phosphate levels at the midpoint of the dosing interval (2 weeks postdose, the time of peak effect) were within the normal range in 85% to 100% of subjects. Measures of phosphate metabolism and bone biomarkers generally improved with burosumab therapy, approaching or reaching their respective normal ranges by study end. Improvements in patient-reported outcomes and mobility were sustained throughout the observation period. No new safety findings emerged with longer-term burosumab treatment. CONCLUSION: These data support the conclusion that burosumab therapy may be a safe and effective long-term treatment option for adult patients with XLH.

CC-486 (oral azacitidine) in patients with myelodysplastic syndromes with pretreatment thrombocytopenia.

Thrombocytopenia is among the strongest predictors of decreased survival for patients with myelodysplastic syndromes (MDS) across all prognostic risk groups. The safety and efficacy of CC-486 (oral azacitidine) was investigated in early-phase studies; we assessed clinical outcomes among subgroups of MDS patients from these studies, defined by presence or lack of pretreatment thrombocytopenia (≤75 × 109/L platelet count). Patients received CC-486 300 mg once-daily for 14 or 21 days of repeated 28-day cycles. Overall, 81 patients with MDS, median age 72 years, comprised the Low Platelets (n = 45) and High Platelets (n = 36) cohorts. Pretreatment median platelet counts were 34 × 109/L and 198 × 109/L, respectively. Grade 3-4 bleeding events occurred in 2 patients in the Low Platelets and 1 patient in the High Platelets groups; events resolved without sequelae. Treatment-related mortality was reported for 7 patients, 5 of whom had pretreatment platelet values <25 × 109/L. Overall response rates were 38% and 46% in the Low Platelets and High Platelets groups, respectively. Five thrombocytopenic patients attained complete remission and 9 attained platelet hematologic improvement. In both cohorts, platelet counts dropped during the first CC-486 treatment cycle, then increased thereafter. Extended CC-486 dosing was generally well tolerated and induced hematologic responses in these patients regardless of pretreatment thrombocytopenia.

CC-486 Maintenance after Stem Cell Transplantation in Patients with Acute Myeloid Leukemia or Myelodysplastic Syndromes.

Relapse is the main cause of treatment failure after allogeneic stem cell transplant (alloSCT) in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). Injectable azacitidine can improve post-transplant outcomes but presents challenges with exposure and compliance. Oral CC-486 allows extended dosing to prolong azacitidine activity. We investigated use of CC-486 maintenance therapy after alloSCT. Adults with MDS or AML in morphologic complete remission at CC-486 initiation (42 to 84 days after alloSCT) were included. Patients received 1 of 4 CC-486 dosing schedules per 28-day cycle for up to 12 cycles. Endpoints included safety, pharmacokinetics, graft-versus-host disease (GVHD) incidence, relapse/progression rate, and survival. Of 30 patients, 7 received CC-486 once daily for 7 days per cycle (200 mg, n = 3; 300 mg, n = 4) and 23 for 14 days per cycle (150 mg, n = 4; 200 mg, n = 19 [expansion cohort]). Grades 3 to 4 adverse events were infrequent and occurred with similar frequency across regimens. Standard concomitant medications did not alter CC-486 pharmacokinetic parameters. Three patients (10%) experienced grade III acute GVHD and 9 experienced chronic GVHD. Of 28 evaluable patients, 6 (21%) relapsed or had progressive disease: 3 of 7 patients (43%) who had received 7-day dosing and 3 of 23 (13%) who had received 14-day dosing. Transplant-related mortality was 3%. At 19 months of follow-up, median overall survival was not reached. Estimated 1-year survival rates were 86% and 81% in the 7-day and 14-day dosing cohorts, respectively. CC-486 maintenance was generally well tolerated, with low rates of relapse, disease progression, and GVHD. CC-486 maintenance may permit epigenetic manipulation of the alloreactive response postallograft. Findings require confirmation in randomized trials. (ClinicalTrials.gov NCT01835587.).

Pharmacokinetics and Pharmacodynamics with Extended Dosing of CC-486 in Patients with Hematologic Malignancies.

UNLABELLED: CC-486 (oral azacitidine) is an epigenetic modifier in development for patients with myelodysplastic syndromes and acute myeloid leukemia. In part 1 of this two-part study, a 7-day CC-486 dosing schedule showed clinical activity, was generally well tolerated, and reduced DNA methylation. Extending dosing of CC-486 beyond 7 days would increase duration of azacitidine exposure. We hypothesized that extended dosing would therefore provide more sustained epigenetic activity. Reported here are the pharmacokinetic (PK) and pharmacodynamic (PD) profiles of CC-486 extended dosing schedules in patients with myelodysplastic syndromes (MDS), chronic myelomonocytic leukemia (CMML) or acute myeloid leukemia (AML) from part 2 of this study. PK and/or PD data were available for 59 patients who were sequentially assigned to 1 of 4 extended CC-486 dosing schedules: 300mg once-daily or 200mg twice-daily for 14 or 21 days per 28-day cycle. Both 300mg once-daily schedules and the 200mg twice-daily 21-day schedule significantly (all P < .05) reduced global DNA methylation in whole blood at all measured time points (days 15, 22, and 28 of the treatment cycle), with sustained hypomethylation at cycle end compared with baseline. CC-486 exposures and reduced DNA methylation were significantly correlated. Patients who had a hematologic response had significantly greater methylation reductions than non-responding patients. These data demonstrate that extended dosing of CC-486 sustains epigenetic effects through the treatment cycle. TRIAL REGISTRATION: ClinicalTrials.gov NCT00528983.

Bone marrow hypocellularity does not affect tolerance or efficacy of azacitidine in patients with higher-risk myelodysplastic syndromes.

The efficacy and tolerance of azacitidine in higher-risk myelodysplasia with hypocellular bone marrow (BM) are unknown. This post hoc AZA-001 trial analysis assessed whether baseline BM cellularity affected the overall survival (OS) advantage demonstrated with azacitidine versus conventional care regimens (CCR). Baseline BM biopsies of <30% cellularity were considered hypocellular with data evaluable from 299 patients (azacitidine n = 154, CCR n = 145); 13% (n = 39) hypocellular, 87% (n = 260) non-hypocellular. Patient characteristics were balanced between cellularity and treatment groups. Most patients (90-100%) had 2-3 cytopenias at baseline. Median (range) azacitidine treatment cycle lengths were 35·5 (28-54) and 33·0 (15-75) d in hypocellular and non-hypocellular groups, respectively. At 33 months, median OS was not reached (NR) [95% confidence interval (CI): 19·2, NR] in hypocellular patients receiving azacitidine versus 16·9 months (95% CI: 11·1, 19·3) with CCR (P = 0·001); and in non-hypocellular patients, it was 21·1 months (95% CI: 16·2, 34·7) versus 15·3 months (95% CI: 9·3, 17·6) (P = 0·012). Azacitidine tolerance was similar regardless of cellularity. Grade 3-4 thrombocytopenia and neutropenia occurred similarly in hypocellular patients treated with azacitidine versus CCR (80% vs. 92% and 88% vs. 75%). Azacitidine OS results are consistent with those from AZA-001, regardless of cellularity, and demonstrate its safety and efficacy in higher-risk myelodysplasia with hypocellular BM.