Dual TORK/DNA-PK inhibition blocks critical signaling pathways in chronic lymphocytic leukemia.

Inhibition of B-cell receptor (BCR) signaling pathways in chronic lymphocytic leukemia (CLL) provides significant clinical benefit to patients, mainly by blocking adhesion of CLL cells in the lymph node microenvironment. The currently applied inhibitors ibrutinib and idelalisib have limited capacity however to induce cell death as monotherapy and are unlikely to eradicate the disease. Acquired resistance to therapy in CLL is often caused by mutations in the response network being targeted, both for DNA damage or BCR signaling pathways. Thus, drugs with dual targeting capacity could offer improved therapeutic value. Here, the potency of CC-115, a novel inhibitor of mammalian target of rapamycin kinase (TORK) and DNA-dependent protein kinase (DNA-PK), was evaluated in primary CLL cells in vitro and in CLL patients. Combined TORK and DNA-PK inhibition in vitro resulted in caspase-dependent cell killing irrespective of p53, ATM, NOTCH1, or SF3B1 status. Proliferation induced by CD40(+) interleukin-21 stimulation was completely blocked by CC-115, and CD40-mediated resistance to fludarabine and venetoclax could be reverted by CC-115. BCR-mediated signaling was inhibited by CC-115 and also in CLL samples obtained from patients with acquired resistance to idelalisib treatment. Clinical efficacy of CC-115 was demonstrated in 8 patients with relapsed/refractory CLL/small lymphocytic lymphoma harboring ATM deletions/mutations; all but 1 patient had a decrease in lymphadenopathy, resulting in 1 IWCLL partial response (PR) and 3 PRs with lymphocytosis. In conclusion, these preclinical results, along with early promising clinical activity, suggest that CC-115 may be developed further for treatment of CLL. The trial was registered at www.clinicaltrials.gov as #NCT01353625.

Fludarabine, cyclophosphamide and rituximab as first-line treatment in patients with newly diagnosed follicular lymphoma.

UNLABELLED: Fludarabine-based regimens are highly effective as first-line therapy in patients with follicular lymphoma. Nevertheless, noticeable haematological toxicity has been reported using fludarabine-based regimens. AIM: To analyse the combination of low-dose oral fludarabine and cyclophosphamide plus rituximab (FCR) as induction therapy, followed by rituximab as maintenance therapy. METHODS: We retrospectively analysed 73 patients diagnosed with low-grade follicular lymphoma treated with two different schemes: attenuated oral (AO) and standard intravenous (SIV) FCR. RESULTS: Overall response rate (ORR) was 95% (complete response rate, CRR 79.5%, partial response, PR 15.4%). CRR was 84.6% in AO vs. 61.9% in SIV (P = 0.058). 44.4% of patients underwent maintenance therapy. Grade 3-4 toxicities included neutropenia: 65.4%; anaemia: 39.7%; thrombocytopenia: five patients; infectious complications: six patients. There were no treatment-related deaths. 6.8% had a secondary malignancy. Progression-free survival (PFS) was 84.6% at 12 yr. The following variables influenced PFS in multivariate analysis: Hb < 12 g/dL [HR 4.7 (95% CI 1.18-18.6)], response after induction [HR 4.9 (95% CI 1.01-24)] for PR vs. CR and [HR 21.27 (95% CI 4.33-104)] for SD/DP vs. CR. OS was 83.1% at 12 yr. The following variables significantly influenced OS in multivariate analysis: not receiving rituximab as maintenance therapy (HR 10.7 (95% CI 1.4-82.5), increased levels of ß2-microglobulin [HR 5.2 (95% CI 1.16-23.7)]. CONCLUSIONS: FCR allowed us to obtain a high response rate, which translated into promising progression free and overall survival with an acceptable and manageable toxicity profile, especially with the attenuated oral scheme.