R-CHOP Preceded By Engineered Tumor Necrosis Factor (TNF) in Patients with Relapsed or Refractory (r/r) Primary CNS Lymphoma (PCNSL): Results of Antitumor Activity, Safety and Blood-Brain Barrier (BBB) Permeabilization in the "Ingrid" Phase II Trial

Background: Almost all PCNSL belong to the category of DLBCL. However, affected pts are treated with high-dose methotrexate-based combinations that are not currently used in other DLBCL and require hospitalization and extensive expertise to manage toxicity. The use of R-CHOP could overcome these difficulties, but CNS availability of related drugs is poor. TNF induces BBB permeabilization and enhances CNS access of anticancer drugs. Coupling TNF with NGR, a peptide that targets CD13⁺ tumor vessels, improves its biological effects and therapeutic index. Thus, we tested the hypothesis that this conjugate (called NGR-hTNF) can break the BBB, thereby improving CNS access and activity of R-CHOP in pts with r/rPCNSL enrolled in a phase II trial (NCT03536039). Herein, we report results of activity, safety and BBB permeabilization.

Methods: HIV-neg adults with PCNSL failed after methotrexate-based chemo and measurable disease were enrolled and treated with 1 course of R-CHOP, followed by 5 courses of R-CHOP21 preceded by NGR-hTNF (0.8 μg/m², 1-h inf). Overall response rate (ORR) was the primary endpoint. The two-stage Simon Minimax design was used; sample size estimated to demonstrate an improvement from 30% ORR (P0) to 50% (P1) (one-sided test; α 10%; β 90%) was 28 pts. NGR-hTNF/RCHOP would be declared active if ≥12 responses were recorded.

As secondary endpoints, changes in vessel permeability, CD13 expression and anticancer drugs pharmacokinetics were assessed in the first 10 pts. Changes in BBB permeability were assessed by Dynamic Contrast Enhanced MRI (DCE-MRI) and ^99mTc-DTPA-SPECT in tumor lesions, perilesional areas and normal appearing brain. DCE-MRI findings recorded before/after the 1^st course (RCHOP alone - baseline) and before/after the 2^nd and 6^th courses (NGR-hTNF/RCHOP) were compared to establish the effect of TNF, and results were expressed as Ktrans values normalized using contralateral white matter. SPECT was performed before and after the 3^rd course, and results were expressed as changes in the volume of ≥30% ^99mTc-DTPA uptake (cm³). CD13 expression was assessed by immunohistochemistry on diagnostic tissue samples. Rituximab, cyclophosphamide and doxorubicin concentrations on matched CSF/plasma samples collected before/after the 1^st, 2^nd and 6^th courses were tested to exclude a non-specific effect of NGR-hTNF on pharmacokinetics.

Results: 22 pts (median age: 58 yo, range 26-78; 11 males) were enrolled; 18 pts had intermediate-high IELSG score. Pts were heavily pretreated: 13 had received ASCT, WBRT or both; 13 had refractory disease. Twenty pts were evaluable for the primary endpoint.

NGR-hTNF/RCHOP combination was active: the predetermined activity threshold (≥12 responses) was achieved, with confirmed tumor response in 13 pts (65%; 95%CI= 45-85%), which was complete in 9. At a median follow-up of 8 months (2-26), 9 pts remain relapse free and 12 pts are alive.

Treatment was well tolerated; toxicities were quickly solved without dose reductions or interruptions. G4 toxicities were neutropenia (49% of courses) and thrombocytopenia (15%), anemia (1%), and FN (1%). Ten SAEs were recorded in 8 pts: g2 seizures (n= 2), g2 DVT (2), g3 infections (2), g3 syncope (2), g4 FN and g2 LVEF reduction. There were 3 cases of g1-2 TNF infusion reaction.

DCE-MRI studies showed an increase of vascular permeability after NGR-hTNF infusion as median (range) Ktrans of tumor and perilesional areas raised from baseline values of 23.5 (6.8-98.8) and 2.5 (0.4-3.9) to 35.3 (23.9-887.7; p= 0.39) and 4.7 (2.2-37.7; p= 0.01), respectively. Likewise, SPECT studies showed a significant enlargement of the volume ≥30% ^99mTc-DTPA uptake, with median (range) values before and after NGR-hTNF infusion of 26 cm³ (5 - 67) and 40 cm³ (10 - 92), respectively (p= 0.02), with a median volume increase of 45% (14-87%). As important features supporting the specificity of the effect of NGR-hTNF, CD13 was expressed in all diagnostic samples, and drug levels in CSF/plasma samples were not influenced by NGR-hTNF.

Conclusions: NGR-hTNF/RCHOP is active and safe in pts with r/rPCNSL. NGR-hTNF enhances vascular permeability specifically in tumor lesions and perilesional areas, which was consistently demonstrated by DCE-MRI, SPECT and plasma/CSF pharmacokinetics studies and was in line with CD13 expression. Accrual completion is warranted. This innovative approach deserves to be addressed as first-line treatment in PCNSL pts.