Orosco-Ttamina, Angel Luis

ABSTRACT Introduction Composite indolent B‐cell lymphomas may remain unrecognized when one component dominates the clinical presentation. Apparent relapse after therapy may, therefore, represent the emergence of a biologically distinct lymphoma rather than the recurrence of the original disease. Case Presentation An 82‐year‐old woman presented with systemic low‐grade B‐cell lymphoma that was most consistent with marginal zone lymphoma (MZL). Staging demonstrated peripheral blood involvement and multifocal FDG‐avid disease. Treatment with the CD20×CD3‐bispecific antibody mosunetuzumab resulted in complete metabolic remission. During surveillance, a new, isolated cervical lymph node developed despite sustained systemic response. Biopsy revealed follicular lymphoma (Grade 1–2) with a germinal center phenotype and a BCL2 rearrangement, findings discordant with recurrence of MZL. Retrospective review of the original specimen identified in situ follicular neoplasia within the initial biopsy. The disease course was, therefore, reinterpreted as a synchronous composite lymphoma in which treatment of the dominant MZL unmasked a previously clinically silent B‐cell neoplasm with follicular lineage. Local radiotherapy achieved remission of the follicular component. Conclusions New disease following treatment of an indolent lymphoma should not automatically be interpreted as relapse. Discordant clinical behavior, particularly focal progression after systemic response, warrants repeat biopsy and integrated pathologic reassessment. This case illustrates how therapy may reveal preexisting clonal heterogeneity and emphasizes the importance of temporality in distinguishing relapse from composite lymphoma. Trial Registration The authors have confirmed clinical trial registration is not needed for this submission

e23554 Background: Radiographic imaging remains the standard of care for disease surveillance and response assessment in soft tissue sarcoma (STS). Circulating tumor DNA (ctDNA) has emerged as a potential biomarker in solid tumors; however, its feasibility and detectability in STS remain incompletely defined due to histologic heterogeneity and variable tumor DNA shedding. We evaluated ctDNA detectability and its relationship to radiographic disease status in the most common STS subtypes: undifferentiated pleomorphic sarcoma (UPS) and leiomyosarcoma (LMS). Methods: We retrospectively analyzed patients with UPS or LMS who underwent serial ctDNA testing using a personalized assay (Signatera) alongside routine radiographic surveillance between 2022 and 2025. Any detectable mean tumor molecules (MTM) >0 was considered positive. ctDNA results were paired with the closest imaging within ±30 days and assessed using radiology report–based determinations of disease status. Exploratory sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were estimated per paired assessment using radiographic progression or recurrence as the reference standard. Results: 13 patients were included (7 female, 6 male), with a median age of 62 years (range 28–75); 7 patients (54%) had LMS and 6 (46%) had UPS. A total of 59 ctDNA–imaging paired assessments were analyzed (median 4 per patient). Overall ctDNA detectability was low and histology-dependent. Baseline ctDNA was detectable in 2 of 13 patients (15%), both with LMS. During longitudinal follow-up, ctDNA remained persistently undetectable in 10 of 13 patients (77%), including all UPS patients and 4 of 7 LMS patients. Detectable ctDNA occurred almost exclusively in LMS and was often observed in association with radiographic disease progression. Across all paired assessments, 46 of 59 (78%) were concordant. Discordance included false-negative ctDNA (negative ctDNA with radiographic disease/progression; n=9) and transient ctDNA positivity without immediate radiographic progression (n=4). Where longitudinal follow-up was available, subsequent ctDNA or imaging assessments frequently demonstrated eventual alignment; lead-time analysis for transient positives was limited by sample size. Using radiographic progression as the reference standard, exploratory per-pair test characteristics demonstrated a sensitivity of approximately 64%, specificity of 88%, PPV of 80%, and NPV of 77%. Conclusions: In this real-world cohort, ctDNA detectability differed by histology and was observed predominantly in LMS. When detectable, ctDNA trends often aligned with radiographic disease progression or recurrence, supporting a potential complementary role in disease monitoring for selected patients. These findings require confirmation in larger, prospective studies.

We report the case of a woman with metastatic alveolar soft part sarcoma (ASPS) who experienced pregnancy-associated disease progression followed by unexpected postpartum regression. Pulmonary lesions increased in size after a miscarriage and during a subsequent pregnancy, prompting consideration for systemic treatment and potential enrolment in a clinical trial evaluating a tyrosine kinase inhibitor in combination with an immune checkpoint inhibitor. However, baseline staging CT performed a few weeks postpartum unexpectedly demonstrated marked spontaneous regression. Because trial enrolment required Response Evaluation Criteria in Solid Tumors-defined radiographic progression, she was deemed ineligible, and no systemic therapy was initiated. Surveillance imaging over the following 2 years confirmed sustained regression and stability of residual disease in the absence of treatment. This case highlights the potential influence of pregnancy-to-postpartum physiology on tumour behaviour through hormonal, immune and angiogenic mechanisms. It also emphasises the importance of short-interval reassessment after delivery before initiation of systemic therapy in reproductive-age patients with metastatic ASPS.

Abstract Background: The coexistence of systemic mastocytosis (SM) and lymphoid neoplasms is rare and remains poorly defined. These cases are classified under SM with associated hematologic neoplasm (SM-AHN) in the WHO framework, though the ICC distinguishes SM with associated myeloid neoplasm (SM-AMN) as a separate entity. Emerging evidence points to SM with associated lymphoid neoplasms (SM-ALN) as a biologically distinct and clinically indolent subgroup (Aperna F et al, 2025). We performed a multisite retrospective study to characterize the clinico-molecular features and outcomes of SM-ALN. Methods: We conducted a retrospective analysis across Mayo Clinic sites, reviewing records from January 1980 to December 2024 to identify patients with SM-ALN. IRB approval was obtained. Of 22 cases identified, 4 were excluded due to co-occurring myeloid neoplasms. The final cohort included 18 patients. Variables analysed included age, sex, SM subtype, KIT mutation, symptoms, treatment, and survival outcomes. Results: Eighteen patients were included (median age: 61.5 years; range: 38–80; 11 female). Most had indolent SM (ISM, n=16); two had aggressive SM (ASM). SM preceded the lymphoid neoplasm in 4 cases (22%), followed it in 6 (33%), and was concurrent in 8 (44%). Low-grade lymphomas (n=12, 67%) included follicular lymphoma (n=2), CLL (, n=2), marginal zone (n=1), lymphoplasmacytic (n=1), and mantle cell (n=1). High-grade lymphomas (n=6, 33%) included diffuse large B-cell lymphoma (DLBCL, n=3), Hodgkin lymphoma (n=2), and T-cell acute lymphoblastic leukemia (n=1). SM-related symptoms were present in 16 of 18 patients (89%). The most common manifestations included dermatologic symptoms (rash/pruritus, 56%), systemic complaints (fatigue/weight loss, 39%), GI symptoms (17%), and anaphylaxis (6%). KIT D816V testing mutation was positive in 10 of 16 patients tested (63%). Tryptase was elevated (>20 ng/mL) in 15 of 18 (83%). NGS data was available for 9 patients: among the two ASM cases, both harbored SRSF2 mutation; one also had JAK2, DNMT3A, RUNX1, TET2, and TP53, while the other carried DNMT3A and IDH1. Mutations observed in ISM cases included CCND3, CXCR4, NOTCH2, SF3B1, MYD88 L265P, ASXL1, and TET2. SM management was divided into two categories: (1) Conservative approach, including observation alone in 4 patients (22%) and symptomatic therapies such as antihistamines or leukotriene inhibitors in 7 (39%); and (2) Cytoreductive treatments, comprising avapritinib in 5 patients (28%), cladribine in 1 (6%), and imatinib in 1 (6%). Management of lymphoid neoplasms included intensive regimens such as R-CHOP and hyper-CVAD for high-grade subtypes (e.g., DLBCL and T-ALL), while indolent forms (e.g., CLL and follicular lymphoma) were treated with bendamustine-rituximab or observation depending on disease burden. Overall, 13 patients (72%) received systemic therapy. At a median follow-up of 81 months (6.7 years), 17 of 18 patients (94%) were alive and progression-free. Median OS and PFS were not reached. The sole death occurred in a patient with ASM, while all ISM cases remained alive. ASM was associated with a higher (though nonsignificant) risk of death (OR 33.0; 95% CI, 0.89–1220.9; p = 0.111). Among patients with high-grade lymphomas (n=5), 80% were alive at follow-up, compared to 100% with indolent lymphomas (n=13). Discussion: Our findings support SM-ALN as a clinically indolent and biologically distinct subset within SM-AHN. Most patients had ISM and low-grade lymphoid neoplasms, with favorable outcomes regardless of lymphoma subtype or diagnostic sequence. High-risk mutations were confined to ASM cases, reinforcing underlying biologic differences. These findings align with prior Mayo Clinic data showing longer survival in SM-ALN compared to SM-AMN (median OS 8.1 vs 2.0 years; p<0.01). Treatment was primarily directed by the lymphoid malignancy, with limited need for cytoreduction in ISM. Larger, prospective studies are needed to confirm these observations and optimize management strategies. Limitations include the study's retrospective, single-center design and limited racial diversity. Multi-institutional studies are warranted to validate these findings and guide optimal management. Conclusion: SM-ALN is a rare but distinct SM subtype characterized by indolent behavior, favorable treatment responses, and prolonged survival. Recognition of this subset is critical to avoid over-treatment and to guide risk-adapted management strategies.

Autologous Chimeric antigen receptor (CAR) T-cell therapies have demonstrated substantial efficacy in patients with relapsed or refractory hematologic malignancies; however, their implementation has been constrained by regulatory barriers. Risk Evaluation and Mitigation Strategies (REMS), mandated by the U.S. Food and Drug Administration (FDA), were initially implemented to mitigate risks associated with cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), and other treatment-related toxicities. On 27 June 2025, the FDA removed REMS requirements for all approved B-cell maturation antigen (BCMA) and CD19-directed autologous CAR T-cell therapies, citing that current product labeling sufficiently communicates safety information. Key regulatory changes include the elimination of site certification and tocilizumab stocking requirements, a reduction in the recommended post-infusion proximity period from four weeks to two weeks, increased flexibility regarding monitoring locations, and a shortened driving restriction from eight weeks to two weeks. This review examines the rationale for the REMS requirements for CAR T-cell therapies, synthesizes contemporary safety data from clinical trials and real-world practice, and explores the implications of this regulatory shift for access to care, particularly in rural and underserved populations. The removal of REMS requirements may facilitate broader implementation of CAR T-cell therapies and alleviate logistical and institutional barriers, offering the potential to expand access while preserving patient safety.