AstraZeneca’s eneboparatide meets the Phase 3 CALYPSO primary endpoint in chronic hypoparathyroidism with full data presented at the European Congress of Endocrinology, Alkermes’ LUMRYZ meets its primary endpoint in the Phase 3 REVITALYZ trial for idiopathic hypersomnia, REGENXBIO’s RGX-202 gene therapy meets the pivotal Phase 3 primary endpoint with high statistical significance in the AFFINITY DUCHENNE trial for Duchenne muscular dystrophy, and Karyopharm’s selinexor plus ruxolitinib combination meets the spleen volume co-primary endpoint in the Phase 3 SENTRY trial for frontline myelofibrosis — the most significant clinical trial results 15 May 2026 has to offer from across the pipeline.
This week delivered a clinically varied and consequential set of readouts spanning rare endocrine disease, sleep medicine, rare genetic disorders, and haematological oncology. The standout result is the pivotal Phase 3 success for RGX-202 in Duchenne muscular dystrophy, marking a potentially significant advance in a devastating rare disease and positioning the therapy as the first in its class to demonstrate statistically significant correlation between its surrogate biomarker endpoint and functional improvement. The remaining readouts extend the week’s rare disease and neurology breadth, with eneboparatide’s full CALYPSO dataset providing important context on both the therapy’s efficacy and the immunogenicity challenges that lie ahead. Here, Life Science Daily News brings you the most significant clinical trial results 15 May 2026.
AstraZeneca’s Eneboparatide Meets Phase 3 CALYPSO Primary Endpoint in Chronic Hypoparathyroidism, with Immunogenicity Signals Observed
AstraZeneca announced on 12 May 2026 late-breaking results from the Phase 3 CALYPSO trial of eneboparatide (AZP-3601), an investigational parathyroid hormone (PTH) 1 receptor agonist, at the European Congress of Endocrinology (ECE 2026) in Prague. The trial met its composite primary endpoint: 31.1% of patients receiving eneboparatide achieved normalisation of albumin-adjusted serum calcium levels and independence from active vitamin D and oral calcium supplements at week 24, compared with 5.9% in the placebo arm (p=0.0001).
CALYPSO was a global, randomised, double-blind, placebo-controlled, multicentre Phase 3 trial enrolling 202 adults with chronic hypoparathyroidism from 12 countries, randomised 2:1 to eneboparatide or placebo. The trial also met all key secondary endpoints at week 24, including normalisation of urinary calcium excretion in patients with hypercalciuria at baseline, achieved in 56.6% of eneboparatide-treated patients versus 20% on placebo (p=0.0001). Statistically significant improvements were also observed in patient-reported outcomes for disease-specific physical symptoms, physical functioning, and SF-36 Physical Function Subscore.
Following the 24-week randomised treatment period, all patients received eneboparatide in an open-label extension to 52 weeks. In the group continuing eneboparatide throughout, clinical benefits were maintained at week 52. Bone health was preserved over 52 weeks, with no clinically significant reduction in bone mineral density and bone turnover markers remaining within normal range. However, immunogenicity was observed in the majority of patients, resulting in reduced treatment effects in some individuals — a finding that analysts have noted may limit eneboparatide’s competitiveness relative to Ascendis Pharma’s approved PTH analogue Yorvipath. Eneboparatide has received Fast Track and Orphan Drug Designations from the FDA and Orphan designation from the EMA. AstraZeneca, which acquired the asset through its $800 million upfront acquisition of Amolyt Pharma in 2024 (total deal value $1.05 billion), has stated it intends to share the results with global regulatory authorities. Chronic hypoparathyroidism affects more than 250,000 people across the United States, European Union, and Japan, with approximately 80% of patients being women.
Alkermes’ LUMRYZ Meets Primary Endpoint in Phase 3 REVITALYZ Trial for Idiopathic Hypersomnia
Alkermes announced on 12 May 2026 positive topline results from the REVITALYZ Phase 3 double-blind, placebo-controlled, randomised withdrawal study evaluating LUMRYZ (sodium oxybate extended-release oral suspension) in adults with idiopathic hypersomnia (IH). LUMRYZ met the study’s primary endpoint, demonstrating a statistically significant improvement in excessive daytime sleepiness compared to placebo as measured by change in Epworth Sleepiness Scale (ESS) score (p<0.0001).
Both key secondary endpoints were also met with high statistical significance (p<0.0001): the Patient Global Impression of Change (PGI-C) and the Idiopathic Hypersomnia Severity Scale (IHSS), with patients in the placebo arm experiencing marked worsening across all three measures following withdrawal from active therapy. The safety profile was consistent with the established safety profile of LUMRYZ, with no new safety signals identified. The most common treatment-emergent adverse events were nausea, headache, anxiety, dizziness, and vomiting.
LUMRYZ is already approved by the FDA for the treatment of excessive daytime sleepiness or cataplexy in patients aged 7 years and older with narcolepsy. Based on the positive REVITALYZ results, Alkermes plans to file a supplemental New Drug Application with the FDA by the end of 2026 to seek approval of LUMRYZ for idiopathic hypersomnia. Notably, under a prior settlement and licence agreement, Alkermes is precluded from marketing LUMRYZ for idiopathic hypersomnia before 1 March 2028, even if regulatory approval is granted — a constraint that limits near-term commercial uptake but positions the company to enter an underserved segment of sleep medicine. Idiopathic hypersomnia is a rare, chronic neurological disorder characterised by excessive daytime sleepiness, prolonged overnight sleep, and significant difficulty waking, for which approved treatment options remain severely limited.
REGENXBIO’s RGX-202 Gene Therapy Meets Pivotal Phase 3 Primary Endpoint in AFFINITY DUCHENNE Trial for Duchenne Muscular Dystrophy
REGENXBIO announced on 14 May 2026 positive topline and interim functional data from the pivotal Phase 3 portion of the Phase I/II/III AFFINITY DUCHENNE trial of RGX-202, an investigational gene therapy for Duchenne muscular dystrophy (DMD). The trial met its primary endpoint with high statistical significance (p<0.0001): 93% of participants achieved microdystrophin expression of at least 10% at week 12 (n=30). Data were cut as of 16 April 2026.
RGX-202 also demonstrated a statistically significant correlation between microdystrophin expression levels and interim functional improvement as measured by the North Star Ambulatory Assessment (NSAA, n=9), a key finding that supports the validity of the microdystrophin surrogate endpoint for regulatory purposes. The therapy was generally well tolerated across 31 participants, with a favourable interim safety profile. Two serious adverse events were reported: one case of subacute myocarditis in an 8-year-old participant, whose subsequent cardiac MRI confirmed no heart muscle fibrosis and no change in ejection fraction, and one case of asymptomatic liver injury in a 10-year-old participant, with normal bilirubin levels and abdominal ultrasound. Both events resolved without sequelae. RGX-202 is the only microdystrophin gene therapy in development for Duchenne to include the C-terminal domain of dystrophin, which has been shown to protect cardiac function and which the company argues is a key differentiating feature of its construct.
AFFINITY DUCHENNE is a Phase I/II/III trial evaluating a single intravenous dose of RGX-202 at 2×10¹⁴ genome copies per kilogram in ambulatory boys aged one year and older with Duchenne. REGENXBIO plans to pursue accelerated approval for RGX-202 based on the microdystrophin surrogate endpoint and is preparing for a potential commercial launch in 2027. The company has enrolled over 20 additional participants in a confirmatory trial (n=30 enrolled) and expects to complete dosing across the pivotal and confirmatory trials by mid-2026. Duchenne muscular dystrophy is an X-linked genetic disease affecting approximately 1 in 3,500 to 5,000 male births globally, caused by mutations in the dystrophin gene that result in progressive muscle degeneration and, without intervention, loss of ambulation typically in the early teenage years.
Karyopharm’s Selinexor Plus Ruxolitinib Meets Spleen Volume Co-Primary Endpoint in Phase 3 SENTRY Trial for Frontline Myelofibrosis
Karyopharm Therapeutics reported results from the Phase 3 SENTRY trial evaluating selinexor 60 mg once weekly in combination with ruxolitinib versus placebo plus ruxolitinib in 353 JAK-inhibitor-naive patients with myelofibrosis. The trial met its first co-primary endpoint: spleen volume reduction of 35% or more (SVR35) was achieved in 50% of patients in the selinexor combination arm versus 28% in the ruxolitinib-alone arm at week 24 (one-sided p<0.0001), with rapid, deep, and sustained improvements observed over time. Karyopharm reiterated and further highlighted these data during its Q1 2026 financial results on 14 May 2026, and the SENTRY results have been selected for a late-breaking oral presentation at the 2026 ASCO Annual Meeting on 2 June 2026.
The trial did not meet its second co-primary endpoint of mean change in absolute total symptom score (Abs-TSS) at week 24, and no meaningful differences were observed between treatment arms in secondary endpoints of progression-free survival, haemoglobin stabilisation, and bone marrow fibrosis improvement as of the data cut-off of 20 February 2026. A post-hoc landmark analysis suggested SVR35 achievement may predict overall survival, and a promising overall survival signal was observed (HR 0.43; 95% CI: 0.19–1.00; p=0.0222). An exploratory endpoint showed that 32% of patients in the selinexor combination arm achieved a reduction of 20% or more in variant allele frequency (VAF) for JAK2, MPL, and CALR mutations, compared with 24% in the ruxolitinib-alone arm, providing early evidence of potential disease modification.
Selinexor is an oral XPO1 (exportin-1) inhibitor already approved in the United States for relapsed or refractory multiple myeloma and diffuse large B-cell lymphoma under the brand name XPOVIO. Myelofibrosis is a rare, progressive blood cancer affecting approximately 20,000 patients in the United States and 17,000 in the European Union, causing extensive bone marrow fibrosis, splenomegaly, and debilitating systemic symptoms. Karyopharm has stated it believes potential inclusion of the selinexor combination in relevant treatment compendia could occur in the second half of 2026. Topline data from the Phase 3 XPORT-EC-042 trial of selinexor in endometrial cancer, which has completed enrolment, are also expected in mid-2026.
Looking Ahead
The most significant clinical trial results 15 May 2026 reflect a pipeline defined by advances in rare disease and genetic medicine. The pivotal Phase 3 success for RGX-202 in Duchenne muscular dystrophy stands as the week’s most impactful result, offering the prospect of a gene therapy that could permanently address the underlying cause of a devastating condition for which treatment options have historically been limited to symptom management. LUMRYZ’s Phase 3 success in idiopathic hypersomnia extends the therapy’s clinical utility into a chronically underserved sleep disorder, though the 2028 marketing restriction means the regulatory path will run ahead of any commercial benefit for several years. AstraZeneca’s full CALYPSO dataset, while confirming the primary endpoint, introduces important immunogenicity questions that the regulatory pathway will need to resolve. And the SENTRY myelofibrosis data, with their mixed endpoint picture but promising survival signal, continue to generate clinical debate ahead of the ASCO presentation that will bring additional scrutiny in June. Life Science Daily News will continue to bring you accurate, timely coverage of the clinical trial results 15 May 2026 that matter most across the global life sciences pipeline.
This clinical trials roundup is produced by the Life Science Daily News editorial team. All stories are selected and written independently.
