Unlabelled

Pancreas ductal adenocarcinoma (PDAC) has one of the worst 5-year survival rates of all solid tumors, and thus new treatment strategies are urgently needed. Here, we report that targeting Bruton tyrosine kinase (BTK), a key B-cell and macrophage kinase, restores T cell-dependent antitumor immune responses, thereby inhibiting PDAC growth and improving responsiveness to standard-of-care chemotherapy. We report that PDAC tumor growth depends on cross-talk between B cells and FcRγ(+) tumor-associated macrophages, resulting in T(H)2-type macrophage programming via BTK activation in a PI3Kγ-dependent manner. Treatment of PDAC-bearing mice with the BTK inhibitor PCI32765 (ibrutinib) or by PI3Kγ inhibition reprogrammed macrophages toward a T(H)1 phenotype that fostered CD8(+) T-cell cytotoxicity, and suppressed PDAC growth, indicating that BTK signaling mediates PDAC immunosuppression. These data indicate that pharmacologic inhibition of BTK in PDAC can reactivate adaptive immune responses, presenting a new therapeutic modality for this devastating tumor type.

Significance

We report that BTK regulates B-cell and macrophage-mediated T-cell suppression in pancreas adenocarcinomas. Inhibition of BTK with the FDA-approved inhibitor ibrutinib restores T cell-dependent antitumor immune responses to inhibit PDAC growth and improves responsiveness to chemotherapy, presenting a new therapeutic modality for pancreas cancer.

Background

Chemoimmunotherapy has led to improved numbers of patients achieving disease response, and longer overall survival in young patients with chronic lymphocytic leukaemia; however, its application in elderly patients has been restricted by substantial myelosuppression and infection. We aimed to assess safety and activity of ibrutinib, an orally administered covalent inhibitor of Bruton tyrosine kinase (BTK), in treatment-naive patients aged 65 years and older with chronic lymphocytic leukaemia.

Methods

In our open-label phase 1b/2 trial, we enrolled previously untreated patients at clinical sites in the USA. Eligible patients were aged at least 65 years, and had symptomatic chronic lymphocytic leukaemia or small lymphocytic lymphoma requiring therapy. Patients received 28 day cycles of once-daily ibrutinib 420 mg or ibrutinib 840 mg. The 840 mg dose was discontinued after enrolment had begun because comparable activity of the doses has been shown. The primary endpoint was the safety of the dose-fixed regimen in terms of frequency and severity of adverse events for all patients who received treatment. This study is registered with ClinicalTrials.gov, number NCT01105247.

Findings

Between May 20, 2010, and Dec 18, 2012, we enrolled 29 patients with chronic lymphocytic leukaemia and two patients with small lymphocytic lymphoma. Median age was 71 years (range 65-84), and 23 (74%) patients were at least 70 years old. Toxicity was mainly of mild-to-moderate severity (grade 1-2). 21 (68%) patients had diarrhoea (grade 1 in 14 [45%] patients, grade 2 in three [10%] patients, and grade 3 in four [13%] patients). 15 (48%) patients developed nausea (grade 1 in 12 [39%] patients and grade 2 in three [10%] patients). Ten (32%) patients developed fatigue (grade 1 in five [16%] patients, grade 2 in four [13%] patients, and grade 3 in one [3%] patient). Three (10%) patients developed grade 3 infections, although no grade 4 or 5 infections occurred. One patient developed grade 3 neutropenia, and one developed grade 4 thrombocytopenia. After a median follow-up of 22.1 months (IQR 18.4-23.2), 22 (71%) of 31 patients achieved an objective response (95% CI 52.0-85.8); four patients (13%) had a complete response, one patient (3%) had a nodular partial response, and 17 (55%) patients had a partial response.

Interpretation

The safety and activity of ibrutinib in elderly, previously untreated patients with symptomatic chronic lymphocytic leukaemia, or small lymphocytic lymphoma is encouraging, and merits further investigation in phase 3 trials.

Funding

Pharmacyclics, Leukemia and Lymphoma Society, D Warren Brown Foundation, Mr and Mrs Michael Thomas, Harry Mangurian Foundation, P50 CA140158 to Prof J C Byrd MD.