Key Points Autologous activated T cells can drive antigen-independent proliferation of CLL cells through CD40 and IL-21 signaling. An IL-21 gene induction signature, IL-21 mRNA, and protein can be found in CLL lymph node samples.

Chronic lymphocytic leukemia (CLL) cells circulating in peripheral blood (PB) differ from the leukemic fraction in lymph nodes (LNs) with respect to cell division and drug sensitivity. CD40 stimulation of PB CLL cells in vitro results in chemoresistance and provides a partial model for the LN microenvironment. The TLR9 ligand CpG induces proliferation in immunoglobulin variable heavychain-unmutated CLL, but apoptosis in immunoglobulin variable heavy-chain-mutated CLL. To juxtapose proliferative with antiapoptotic signals, we investigated the effects of CpG in the context of CD40 ligation in mutated versus unmutated CLL cells in this study. Prolonged CD40 ligation induced classical, followed by alternative nuclear factor-jB (NF-jB), activity in both subgroups, correlating with enhanced Bfl-1 and Bcl-X L levels, respectively. A dichotomy in NF-jB signaling occurred on combined CD40/TLR9 triggering. This induced declining p52 and Bcl-X L levels, and reversed chemoresistance only in mutated cells, whereas unmutated cells proliferated, maintained p52 and Bcl-X L and remained chemoresistant. The pivotal contribution of Bcl-X L to chemoresistance was shown by the BH3 mimetic ABT-737 and RNA interference. Finally, in ex vivo LN samples, p52, p65 and Bcl-X L levels were highly expressed, corroborating the in vitro findings. Thus, a distinction in NF-jB activation and drug susceptibility in mutated versus unmutated (LN-like) CLL cells was uncovered, which was causally linked to Bcl-X L levels.

2538 Background: There is a high unmet medical need for effective treatments for patients with recurrent, metastatic, or persistent cervical cancer. Most patients are young and survival rates are poor. ORR for second line therapies is between 4 and 14% for chemotherapy and recently approved immunotherapy. Adoptive cell transfer using tumor infiltrating lymphocytes (TIL) have demonstrated durable responses in some patients with recurrent cervical cancer thus offering the potential for long-term disease control. Methods: Study C-145-04 is an ongoing, open-label, multicenter Phase 2 clinical trial evaluating the safety and efficacy of LN-145 TIL therapy in patients with advanced cervical cancer who have undergone at least one prior line of chemotherapy. Prior checkpoint inhibitor therapy is an exclusion criterion. The primary endpoint is ORR per RECIST 1.1; secondary endpoints include duration of response (DOR), disease control rate (DCR), and LN-145 safety. Tumors surgically harvested at local institutions are shipped to central GMP facilities for TIL generation in a 22-day manufacturing process. Final LN-145 TIL product is cryopreserved and shipped to sites. Patients receive one week of preconditioning lymphodepletion (cyclophosphamide, fludarabine), a single LN-145 infusion, followed by up to 6 doses of IL-2 (600,000 IU/kg). Results: As of 4 Feb 2019, 27 efficacy-c patients have received Gen 2 of LN-145, with a mean age of 47 years and 2.6 mean prior lines of therapy. Preliminary efficacy results: ORR was 44% (1 CR, 9 PR, 2 uPR), DCR was 89% at 3.5-month median study follow-up with 11/12 patients maintaining their response. Improved responses were observed in 4 patients with longer follow-up. Mean TIL cells infused was 28x109. Median IL-2 doses administered was 6.0. The adverse event profile was generally consistent with the underlying advanced disease and the profile of the lymphodepletion and IL-2 regimens. Conclusions: LN-145 results in 44% ORR in previously treated cervical cancer patients with acceptable safety and efficacy profile. LN-145 offers patients a viable therapeutic option warranting further investigation. Clinical trial information: NCT03108495.

Purpose: Chronic lymphocytic leukemia (CLL) cells in lymph nodes (LN), from which relapses are postulated to originate, display an antiapoptotic profile in contrast to CLL cells from peripheral blood (PB). The BH3 mimetic ABT-737 antagonizes the antiapoptotic proteins Bcl-X L and Bcl-2 but not Mcl-1 or Bfl-1. Previously, it was shown that CD40-stimulated CLL cells were resistant to ABT-737. We aimed to define which antiapoptotic proteins determine resistance to ABT-737 in CLL and whether combination of known antileukemia drugs and ABT-737 was able to induce apoptosis of CD40-stimulated CLL cells.Experimental Design: To mimic the LN microenvironment, PB lymphocytes of CLL patients were cultured on feeder cells expressing CD40L and treated with ABT-737 with or without various drugs. In addition, we carried out overexpression or knockdown of pro-and antiapoptotic proteins in immortalized primary B cells.Results: Upon CD40 stimulation patient-specific variations in ABT-737 sensitivity correlated with differences in levels of Mcl-1 and its antagonist Noxa. Knockdown of Noxa, as well as Mcl-1 overexpression, corroborated the importance of the Noxa/Mcl-1 ratio in determining the response to ABT-737. Inhibition of NF-kB resulted in increased Noxa levels and enhanced sensitivity to ABT-737. Interestingly, increasing the Noxa/Mcl-1 ratio, by decreasing Mcl-1 (dasatinib and roscovitine) or increasing Noxa levels (fludarabine and bortezomib), resulted in synergy with ABT-737.Conclusions: Thus, the Noxa/Mcl-1 balance determines sensitivity to ABT-737 in CD40-stimulated CLL cells. These data provide a rationale to investigate the combination of drugs which enhance the Noxa/Mcl-1 balance with ABT-737 to eradicate CLL in chemoresistant niches.