Prula-cel's Immunosuppressant-Free Signal Is Real but Rests on Uncontrolled, Underpowered Data

Adicet's Off-the-Shelf CAR-T Shows Promise in Lupus Trial

Adicet Bio's allogeneic gamma delta CAR-T therapy, prula-cel, demonstrated promising early-stage clinical results in lupus nephritis patients. After a year of follow-up, 50% achieved a complete kidney response and 54% met remission criteria, with all evaluable patients discontinuing immunosuppressants. The therapy also showed a favorable safety profile, with no serious cytokine release syndrome or neurological side effects, addressing key concerns associated with CAR-T treatments. Adicet plans to initiate a pivotal study in lupus in the fourth quarter.

• In an early-stage trial, prula-cel achieved significant efficacy in lupus nephritis patients, with 50% experiencing a complete kidney response and 54% reaching remission after one year. Crucially, all these patients were able to stop their chronic immunosuppressive medications, highlighting the potential for a "reset" of the immune system and offering a new therapeutic paradigm for those who have failed multiple prior treatments.
• The therapy exhibited a favorable safety profile, notably with no serious cases of cytokine release syndrome (CRS) or neurological side effects, which are common concerns with CAR-T therapies. This safety advantage is attributed to prula-cel's gamma delta T-cell basis, which secretes fewer inflammatory cytokines compared to conventional alpha beta CAR-T cells, potentially reducing the risk of severe immune-related adverse events.
• Prula-cel is an allogeneic, "off-the-shelf" CAR-T therapy derived from donor cells, offering a more practical, quicker, and less costly manufacturing process than personalized CAR-T treatments. This approach aims to overcome the logistical and cost limitations of individualized therapies, making it potentially more suitable for widespread use in autoimmune conditions and expanding access to this advanced treatment modality.

Why New Approaches are Needed for Lupus Management

Despite advances in immunosuppressive therapy, current treatment approaches for lupus fall short of achieving consistent disease control, leaving a substantial proportion of patients at risk for progressive organ damage, treatment-related toxicity, and reduced long-term survival.

• Incomplete and heterogeneous treatment response: Standard induction regimens combining corticosteroids with cyclophosphamide or mycophenolate mofetil do not achieve clinical remission in all patients. In lupus nephritis specifically, slow and incomplete responses to induction therapy, combined with high relapse rates on maintenance treatment, continue to drive progression to end-stage renal failure in a significant proportion of patients.

• Corticosteroid-related damage accrual: Prolonged corticosteroid exposure is a primary driver of long-term organ damage in SLE, independent of disease activity itself. Reducing glucocorticoid burden remains a central but unresolved challenge; current standard-of-care regimens frequently require sustained steroid use to maintain disease control.

• Limited efficacy in refractory and severe disease subsets: Patients refractory to conventional immunosuppressives, including intravenous cyclophosphamide, represent a particularly difficult-to-treat population. In rapidly progressive crescentic lupus nephritis with significant renal impairment, even B-cell depletion with rituximab may not prevent progression to end-stage renal failure and dialysis.

• Unmet need in neuropsychiatric SLE (NPSLE): NPSLE remains the least understood manifestation of lupus. Its multifactorial pathogenesis and heterogeneous clinical presentation — encompassing psychosis, seizures, acute confusional state, and headache — complicate both diagnosis and treatment selection. Randomized controlled trial evidence for any agent in NPSLE is absent, and management relies on individualized strategies extrapolated from broader SLE data.

• Racial and geographic disparities in treatment access and outcomes: Asian and African American patients exhibit higher prevalence and greater severity of lupus nephritis compared to Caucasian patients. Despite the proven efficacy of mycophenolate mofetil across populations, its high cost limits access in parts of Asia, and evidence supporting reduced-dose intravenous cyclophosphamide — validated in European Caucasian cohorts — has not been formally evaluated in Asian populations.

• Safety burden limiting treatment adherence: Immunosuppressive regimens carry significant infection risk and other adverse events that drive discontinuation. In a real-world Japanese cohort of 119 SLE patients receiving mycophenolate mofetil, the cumulative discontinuation rate reached 42.4%, with 29 patients discontinuing due to adverse events, including two cases of irreversible viral meningitis complications associated with high mycophenolic acid trough concentrations.

Prula-cel's Promising Early Data in Lupus Nephritis

Recent clinical trials in systemic lupus erythematosus (SLE) have evaluated a range of biologic and small-molecule interventions across phase 2 and phase 3 settings, with outcomes assessed using composite indices including BICLA, SRI(4), and organ-specific measures. The studies below represent key data points from the anifrolumab, belimumab, and baricitinib programmes, spanning efficacy, corticosteroid sparing, and safety.

Prula-cel's Promise: A New Era for Lupus Nephritis

The promising early-stage data for Adicet Bio's allogeneic gamma delta CAR-T therapy, prula-cel, in lupus nephritis (LN) signals a potential paradigm shift in how severe autoimmune diseases might be managed. For patients grappling with LN, the prospect of achieving deep, sustained remission and, crucially, discontinuing chronic immunosuppressive medications is a significant beacon of hope. Current treatment regimens, while effective for many, often necessitate long-term drug exposure, leading to a host of side effects and a persistent risk of disease flares, even after achieving remission.

Prula-cel's ability to induce high rates of complete kidney response and remission, coupled with the complete withdrawal of immunosuppressants in all evaluable patients after a year, suggests a profound and potentially curative impact. This is further bolstered by a favorable safety profile, notably the absence of serious cytokine release syndrome or neurological toxicities, which are common concerns with other CAR-T approaches. The allogeneic nature of prula-cel is also a strategic advantage, offering an 'off-the-shelf' solution that could overcome the logistical hurdles and manufacturing timelines associated with autologous cell therapies, thereby enhancing accessibility for a wider patient population.

However, as with any groundbreaking therapy, important considerations remain.

• The long-term durability of these remissions will be critical. Historical data indicates that flares are not uncommon after immunosuppressant discontinuation in SLE patients, even those in remission, and maintenance therapies like antimalarials have shown protective effects.

• The translation of these early-stage results to a larger, more diverse patient cohort in pivotal studies will be key. Lupus nephritis is a heterogeneous disease, and patient characteristics can influence treatment response.

• While initial safety is encouraging, comprehensive long-term follow-up is essential to fully characterize the safety profile of an allogeneic cell therapy in an autoimmune setting.

Adicet's plan to initiate a pivotal study in lupus later this year underscores the confidence in prula-cel's potential. If these results are replicated in larger trials, prula-cel could not only transform the treatment landscape for lupus nephritis but also validate the broader application of allogeneic gamma delta CAR-T platforms across a spectrum of autoimmune conditions, offering a new frontier in immune modulation.