Intracellular calcium dynamics are central to cellular physiology. The principal mechanism for refilling depleted intracellular stores is store-operated calcium entry (SOCE), mediated by the Ca2+ release-activated Ca2+ (CRAC) channel. CRAC channel opening is driven by the interaction between the endoplasmic reticulum Ca2+ sensor STIM1 and the pore-forming protein Orai1. Because SOCE regulates processes across immune cells, stromal populations and other tissues, dysregulation of this pathway contributes to a range of human pathologies, notably immune disorders and features associated with cancer.
Given this central role, Orai1 has emerged as a promising target for precision therapeutics aimed at modulating pathological calcium influx while preserving necessary physiological signalling.
Pharmacological modulation of CRAC channels has progressed through distinct stages. Early chemical tools such as SKF-96365 provided proof-of-concept that chemical blockade of SOCE could alter cellular responses, but these early compounds exhibited substantial off-target effects that limited their translational utility.
Subsequent, second-generation agents focused on improved selectivity and pore blockade. Examples discussed include Synta66, RO2959 and GSK-7975A. These agents represented a meaningful advance over first-generation tools by reducing non-specific interactions, yet they still faced challenges for clinical deployment related to specificity, pharmacokinetics or safety profiles.
Third-generation CRAC inhibitors mark the transition from preclinical tools to therapeutic candidates evaluated in human studies. The review highlights CM4620 (zegocractin) as a leading intravenous third-generation inhibitor. CM4620 has been evaluated in Phase 2 clinical trials across several acute indications. The review specifically references Phase 2 programs in acute pancreatitis (CARPO), severe COVID-19 pneumonia (CARDEA) and acute kidney injury (KOURAGE).
The included discussion focuses on the clinical development trajectory rather than presenting detailed trial outcomes in this summary. The authors emphasize that CM4620 exemplifies an approach aimed at acute, intravenous modulation of SOCE to blunt pathological inflammation and organ injury in critical-care settings.
Alongside intravenous programs, the pharmacological portfolio is expanding toward orally bioavailable CRAC inhibitors intended for chronic disease modulation. The review mentions candidate molecules such as CM5480 that are being developed with the goal of addressing chronic cardiopulmonary remodelling and long-term immunomodulatory indications.
This oral approach is positioned as complementary to acute intravenous therapy: where short-term suppression of catastrophic calcium-driven inflammation may be desirable in critical illness, long-term, orally dosed agents may support disease modification in chronic conditions.
A prominent theme is that targeting a ubiquitous signalling pathway like SOCE requires thoughtful clinical strategy. The authors argue for biomarker-driven stratification of patient cohorts to increase the likelihood of demonstrating efficacy while limiting off-target or systemic effects. Trial designs will need to consider indication-specific endpoints, timing and duration of intervention (acute intravenous versus chronic oral), and safety monitoring tailored to calcium signalling modulation.
The review positions biomarker-guided enrollment and outcome selection as key steps for translating molecular understanding of Orai1 into clinical benefit.
Looking forward, the authors anticipate two major lines of therapeutic development. First, acute intravenous CRAC inhibition for critical-care indications; second, chronic oral immunomodulation for long-term disease management. Beyond this practical bifurcation, the review identifies isoform-selective strategies as the next frontier: exploiting tissue- and disease-specific expression patterns of Orai family members, particularly Orai2 and Orai3, could improve therapeutic index and enable tailored interventions for distinct disorders.
By combining isoform-directed pharmacology with biomarker-driven clinical frameworks, the field aims to refine SOCE-targeted therapies into safer and more effective options across both acute and chronic disease settings.
When internal calcium stores fall, the STIM1–Orai1 interaction opens a CRAC channel to let calcium back into the cell. Overactive calcium entry through this pathway can drive tissue damage and inflammation in multiple diseases. Drug development has moved from broadly acting chemical inhibitors to more selective pore blockers. Intravenous third-generation agents such as CM4620 are being tested in Phase 2 trials for acute conditions, and oral candidates like CM5480 are under development for chronic disease. Critical next steps include biomarker-based trial design and pursuing isoform-specific targeting to increase safety and efficacy.