Large granular lymphocytic leukemia: 2026 so far

Treatment evidence broadened beyond immunosuppression into newer agents.

New in the months covered, two small retrospective reports (looking back at past care, not a planned trial) described high response rates with golidocitinib (a JAK1 inhibitor) in relapsed/refractory LGLL and with bendamustine in high-burden T-LGLL. Follow-up was short in the golidocitinib series (about 4 months). The bendamustine cohort included longer follow-up (including a 3-year progression-free survival estimate), but neither report was randomized. Both reports described side effects that often involved low blood counts (cytopenias, meaning too-low blood cell levels). In the bendamustine cohort, two people stopped treatment due to toxicity. In these reports, the practical message is that these are early signals of additional options, along with the need to watch closely for low counts and other treatment-related toxicity.

Research covered in: September 2026

Routine-care cohorts reinforced immunosuppression responses and tolerability limits.

In the months covered, real-world cohorts continued to report that immunosuppressive approaches (medicines that dampen an overactive immune system) are commonly used and often followed by improvement in LGLL. A small single-center LGLL series reported responses after first-line immunosuppressive therapy in most treated patients, alongside common presenting problems like fatigue and cytopenias. In a separate single-center NK-LGLL cohort, frontline cyclosporine or cyclophosphamide was linked with complete remissions in about two-thirds of treated patients, and some patients switched therapies due to side effects rather than clear disease worsening. These reports describe immunosuppression as a common starting point in routine care, where both response and day-to-day tolerability shape what happens next.

Research covered in: April 2026, July 2026, September 2026

Overlap with plasma cell disorders gained clearer frequency and subgroup signals.

New in August, a large cross-sectional analysis (a snapshot across many people at one point in time) reported that LGLL and plasma cell disorders (conditions involving antibody-making plasma cells) often appeared together (plasma cell disorders in 20% of LGLL cases; LGLL in 2% of plasma cell disorder cases). It also reported that overlap cases had more autoimmune conditions and more severe immune-mediated cytopenias. The same report suggested heterogeneity within overlap cases: in one symptomatic subgroup with low plasma-cell infiltration, B-cell-targeted therapies performed better than immunosuppression (not described as randomized). In this dataset, having a co-existing plasma cell disorder was linked with more complicated immune-related low blood counts, and the best-looking treatment comparisons depended on which overlap subgroup a person fit into.

Research covered in: August 2026

Expert guidance converged on shared definitions and fewer diagnostic pitfalls.

In the months covered, several expert publications focused on making LGLL diagnosis and response assessment more consistent across centers. An international expert consensus proposed shared criteria for diagnosing T-LGLL, deciding when treatment is considered, and judging response. A separate national expert consensus summarized diagnostic criteria, common medicines, monitoring considerations, and safety concerns with immunosuppressive treatments. A best-practices paper also emphasized pitfalls in interpreting NK-cell flow cytometry (a blood test that sorts cells by surface markers) including limits of KIR-based clonality inference, and it proposed an operational reflex approach when NK-cell expansions or abnormal patterns are seen. This kind of guidance mainly affects how confidently LGLL is labeled and compared across clinics and studies, which can influence how clear and consistent your workup and follow-up feel from one center to another.

Research covered in: August 2026, September 2026

More studies highlighted infection/reactive patterns that resemble LGLL.

In several months, papers added practical details on why an LGLL workup often needs more than one test and careful clinical context. Comparative data supported T-cell receptor (TCR) gene rearrangement testing (a DNA test for a clonal T-cell population) as frequently positive in T-LGLL and less common in several look-alike control groups, while one flow-based clonality approach (TRBC1) detected fewer cases in that setting. Other reports highlighted that some T-cell disorders can look NK-like on routine markers but still show clonal TCR evidence. Additional studies emphasized mimic scenarios: CMV viremia-associated NK expansions (CMV in the blood, linked with temporary immune cell increases) that can meet NK-LGLL criteria, with NKG2C proposed as a helpful marker in that setting, and substantial overlap between leukemic and reactive T-LGL flow patterns despite some markers being more common in T-LGLL. In these reports, borderline or conflicting lab results were treated as a known issue, and gene-based clonality testing plus context-specific marker choices were used to lower the chance of misclassification.

Research covered in: February 2026, March 2026, May 2026, July 2026, September 2026