Relapsed or refractory (R/R) diffuse large B-cell lymphoma (DLBCL) in those unfit or ineligible for autologous stem cell transplantation is associated with a poor outcome and new treatment approaches are needed. Pixantrone is a novel aza-anthracenedione which is structurally similar to anthracyclines and is licenced in R/R DLBCL and National Institute for Health and Care Excellence (NICE)-approved following the PIX301 trial. No data exist post-NICE approval. We performed a UK-wide retrospective multi-centre study of 92 R/R DLBCL who received pixantrone. Eighty-five per cent had refractory disease and 72% had an international prognostic index (IPI) 3-5 at commencement of pixantrone. The median progression-free survival (PFS) was 2·0 months (95% confidence interval (CI) 1·5-2·4) and the median overall survival was 3·4 months (95% CI 2·7-4·5). The overall response rate was 24% (complete response 10%; partial response 14%). We demonstrate that pixantrone has limited activity in a cohort of high risk, predominantly refractory DLBCL. Multivariate Cox regression revealed that patients who relapsed >12 months after first line treatment, those with fewer prior lines of therapy and relapsed (non-refractory) DLBCL had improved PFS. The major population of unmet need are those with refractory DLBCL who are poorly represented within trials and in whom pixantrone appears less efficacious compared to relapsed DLBCL.

Southwest Oncology Group (Bernstein et al, 2009). As expected, these patients had more advanced disease and more frequent extranodal localization at presentation. In this study, we demonstrated that the addition of rituximab to CHOP was associated with a reduction in the incidence of secondary CNS involvement. Moreover, compared to the pre-rituximab era, progression during systemic treatment is less frequent, CNS relapses tend to be isolated and, most strikingly, leptomeningeal involvement is uncommon. These findings are similar to the Vancouver group's study (Villa et al, 2010). The reduced incidence of secondary CNS involvement was also demonstrated by Boehme et al, 2009; and Shimazu et al, 2009;. However, a greater proportion of leptomeningeal relapses in R-CHOP-treated patients was observed in the former study. Conversely, the addition of rituximab did not change the incidence of secondary CNS involvement in the other three studies (Feugier et al, 2004; : Yamamoto et al, 2010; Tai et al, 2011). In contrast to previous studies, our R-CHOP-treated patients with secondary CNS involvement were younger and, probably for that reason, half of them were successfully salvaged with second-line treatment.

7549 Background: Receptor tyrosine kinase-like Orphan Receptor 1 (ROR1) is a type I transmembrane protein is highly expressed on an array of haematological and solid tumours. NVG-111 is a humanised, tandem scFv ROR1xCD3 bispecific antibody previously shown to elicit potent killing of tumour cells in vitro and in vivo by engaging a membrane-proximal epitope in the Wnt5a-binding Frizzled domain of ROR1 and redirecting T cell activity. The in vitro potency and pharmacodynamic responses to NVG-111 were assessed to support progression to a first-in-human study. Methods: The potency of NVG-111 in vitro was determined by evaluating the concentration response for cytotoxicity, T cell activation, and cytokine release in co-cultured Jeko-1 and unstimulated human T cells. Comparative data were generated for the marketed CD19xCD3 bispecific antibody, blinatumomab. Potency data for NVG-111 were used together with allometric scaling from murine PK studies to inform planned clinical doses. Results: NVG-111 demonstrated T cell-dependent cytotoxicity, T cell activation and levels of cytokine release similar in potency to blinatumomab. Cytotoxic responses of both NVG-111 and blinatumomab were more potent than T cell activation and cytokine release. Dose response curves for NVG-111 showed a decrease in activity beyond the concentration of maximal response (ie “hook effect”). We hypothesise this is due to receptor saturation, inhibiting synapse formation. NVG-111 has progressed to a Phase 1/2 first-in-human study in patients with debulked, relapsed/refractory chronic lymphocytic leukemia (CLL) and mantle cell lymphoma (MCL), the drug given as add-on to ≥2nd line therapy with a Bruton’s tyrosine kinase inhibitor, or venetoclax. Phase 1 includes escalating doses of 0.3 to 360 µg/day via continuous infusion over 3 cycles (each 21 days on, 7 days off) to establish safety, PK, pharmacodynamics (PD) and recommended phase 2 dose (RP2D). Predicted exposure at 0.3 µg/day is ̃EC20 for cytotoxicity in vitro and below the lowest EC10 for cytokine release. PD biomarkers in the study include systemic cytokines. Phase 2 will study efficacy and safety of the RP2D in CLL and MCL, with primary endpoint complete response rate; other efficacy endpoints include minimal residual disease and progression free survival. Conclusions: NVG-111 shows potent T-cell mediated lymphoma cell cytotoxicity in vitro at concentrations well below those associated with extensive cytokine release. NVG-111 is in an ongoing Phase 1/2 study and may present a novel option for adoptive immunotherapy in patients with non-Hodgkin lymphoma and potentially other cancers. Clinical trial information: 2020-000820-20. [Table: see text]

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