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Non-Hodgkin lymphomas (NHL) represent the most common hematologic malignancies. Patient-derived xenografts (PDXs) are used for various aspects of translational research including preclinical in vivo validation of experimental treatment approaches. While it was repeatedly demonstrated that PDXs keep majority of somatic mutations with the primary lymphoma samples, from which they were derived, the composition of PDX tumor microenvironment (TME) has not been extensively studied. We carried out a comparative genetic and histopathological study of 15 PDX models derived from patients with various types of NHL including diffuse large B-cell lymphoma (DLBCL; n = 7), Burkitt lymphoma (BL; n = 1), mantle cell lymphoma (MCL; n = 2), and peripheral T-cell lymphomas (PTCL; n = 5). Whole exome sequencing (WES) of the PDXs and primary lymphoma cells was implemented in 13 out of 15 cases with available DNA samples. Standard immunohistochemistry (IHC) was used to analyze the composition of PDX TME. WES data confirmed that PDXs maintained the genetic heterogeneity with the original primary lymphoma cells. In contrast, IHC analysis revealed the following recurrently observed alterations in the composition of PDX tumors: more blastoid lymphoma cell morphology, increased proliferation rate, lack of non-malignant cellular components including T cells and (human or murine) macrophages, and significantly lower intratumoral microvessel density and microvessel area composed of murine vessels. In addition, PDX tumors derived from T-NHL displayed additional differences compared to the primary lymphoma samples including markedly lower desmoplasia (i.e., the extent of both reticular and collagen fibrosis), loss of expression of cytotoxic granules (i.e., perforin, TIA, granzyme B), or loss of expression of T-cell specific antigens (i.e., CD3, CD4, CD8). Our data suggest that despite keeping the same genetic profiles, PDX models of aggressive NHL do not recapitulate the microenvironmental heterogeneity of the original lymphomas. These findings have implications on the relevance of PDX models in the context of preclinical research.

Chemoimmunotherapy with bendamustine and rituximab is an alternative treatment for elderly patients with CLL. The aim of this observational multicenter study was to prospectively assess efficacy and safety of bendamustine and rituximab in front-line therapy in patients with CLL and significant comorbidities in real hematological practice. Eighty-three consecutive patients with cumulative illness rating scale (CIRS) >6 who received at least one cycle of BR as first-line treatment were included in the study. The median age was 71 years (range, 53–83), the median CIRS was 8 (range, 7–17), and 60.2% of patients had a creatinine clearance ≤70 mL/min. FISH analysis, available for 78 cases, showed a del(17p) in 11.5% and del(11q) in 20.5% of patients. Overall response rate was 88.0% with a complete response rate of 20.5%. With median follow-up time of 22 months, the estimated median progression free survival was 35.9 months. Progression free survival and overall survival rates at 2 years were 69.9% and 96.2%, respectively. Grade 3 or 4 neutropenia, thrombocytopenia, and anemia were documented in 40 (48.2%), 14 (16.9%), and 8 (9.6%) patients, respectively. Grade 3 or 4 infections occurred in 14.5% of patients. Chemoimmunotherapy with BR is an effective therapeutic option with manageable toxicity for the initial treatment of CLL patients with significant comorbidities. ClinicalTrials.gov Identifier: NCT02381899.

Context PD-1 immune checkpoint inhibitors, including nivolumab, have shown strong activity in patients with R/R cHL. The CheckMate 205 study demonstrated an objective response rate (ORR) of 69%, a median duration of response (DOR) of 17 months, and median progression-free survival (PFS) of 15 months, at a median follow-up of 18 months. Objective Assess the longer-term outcomes of CheckMate 205 with a median follow-up of 58 months. Design CheckMate 205 (NCT02181738) enrolled patients with R/R cHL after auto-HCT failure into three cohorts by treatment history: (A) brentuximab vedotin (BV)-naive, (B) BV after auto-HCT, and (C) BV before and/or after auto-HCT. Interventions Nivolumab 3 mg/kg every 2 weeks until disease progression or unacceptable toxicity. Patients in cohort C discontinued nivolumab after 1 year in complete remission (CR) with the option to resume within 2 years if relapsed. Outcome Measures Primary: ORR. Others: CR, DOR, PFS, overall survival (OS), and safety. Results Overall, 243 patients were treated. Median duration of treatment was 14 months. ORR was 71% (95% CI, 65%–77%), and CR rate was 21%. Median PFS was 15 months (95% CI, 11–19), and median DOR was 18 months (95% CI, 15–26). The 2-year and 5-year OS rates (95% CI) were 87% (82%–91%) and 71% (65%–77%), and PFS rates were 37% (30%–44%) and 18% (12%–25%), respectively. Patients with CR had improved OS; failure to achieve disease control was a poor prognostic factor for OS. Per protocol, 12 patients in cohort C stopped treatment after ≥1 year of CR. After median of 48 months (range, 36–55) from last treatment, 6 patients were still in response; 3 were re-treated with nivolumab after disease progression (2 re-achieved CR; 1 partial response). The safety profile is similar to previous reports, and no new toxicities were observed. There were no treatment-related deaths. Conclusions This 5-year analysis of CheckMate 205 demonstrated favorable OS and confirmed the efficacy and safety of nivolumab for patients with R/R cHL after auto-HCT. It appears feasible to stop nivolumab after 1 year of CR and re-initiate treatment upon disease progression. Funding BMS. Previous presentation ICML 2021

Mantle cell lymphoma (MCL) is a rare subtype of B-cell non-Hodgkin lymphoma (B-NHL) with chronically relapsing clinical course. Implementation of cytarabine (araC) into induction and salvage regimen became standard of care for majority of MCL patients. In this study, tailored N-(2-hydroxypropyl)methacrylamide (HPMA)-based polymer nanotherapeutics containing covalently bound araC (araC co-polymers) were designed, synthesized and evaluated for their anti-lymphoma efficacy in vivo using a panel of six patient-derived lymphoma xenografts (PDX) derived from newly diagnosed and relapsed / refractory (R/R) MCL. While free araC led to temporary inhibition of growth of MCL tumors, araC co-polymers induced long-term disappearance of the engrafted lymphomas with no observed toxicity even in the case of PDX models derived from patients, who relapsed after high-dose araC-based treatments. The results provide sound preclinical rationale for the use of HPMA-based araC co-polymers in induction, salvage or palliative therapy of MCL patients.

Clinical application of human multipotent mesenchymal stromal cells (hMSCs) requires their expansion to be safe and rapid. We aimed to develop an expansion protocol which would avoid xenogeneic proteins, including fetal calf serum (FCS), and which would shorten the cultivation time and avoid multiple passaging. First, we have compared research-grade alpha-MEM medium with clinical grade CellGro for Hematopoietic Cells' Medium. When FCS was used for supplementation and non-adherent cells were discarded, both media were comparable. Both media were comparable also when pooled human serum (hS) was used instead of FCS, but the numbers of hMSCs were lower when non-adherent cells were discarded. However, significantly more hMSCs were obtained both in alpha-MEM and in CellGro supplemented with hS when the non-adherent cells were left in the culture. Furthermore, addition of recombinant cytokines and other supplements (EGF, PDGF-BB, M-CSF, FGF-2, dexamethasone, insulin and ascorbic acid) to the CellGro co-culture system with hS led to 40-fold increase of hMSCs' yield after two weeks of cultivation compared to alpha-MEM with FCS. The hMSCs expanded in the described co-culture system retain their osteogenic, adipogenic and chondrogenic differentiation potential in vitro and produce bone-like mineralized tissue when propagated on 3D polylactide scaffolds in immunodeficient mice. Our protocol thus allows for very effective one-step, xenogeneic protein-free expansion of hMSCs, which can be easily transferred into good manufacturing practice (GMP) conditions for large-scale, clinical-grade production of hMSCs for purposes of tissue engineering.