Long-term efficacy of first-line ibrutinib treatment for chronic lymphocytic leukaemia in patients with TP53 aberrations : a pooled analysis from four clinical trials

TP53 aberrations [del(17p) or TP53 mutation] predict poor survival with chemoimmunotherapy in patients with chronic lymphocytic leukaemia (CLL). We evaluated long-term efficacy and safety of first-line ibrutinib-based therapy in patients with CLL bearing TP53 aberrations in a pooled analysis across four studies: PCYC-1122e, RESONATE-2 (PCYC-1115/16), iLLUMINATE (PCYC-1130) and ECOG-ACRIN E1912. The pooled analysis included 89 patients with TP53 aberrations receiving first-line treatment with single-agent ibrutinib (n = 45) or ibrutinib in combination with an anti-CD20 antibody (n = 44). All 89 patients had del(17p) (53% of 89 patients) and/or TP53 mutation (91% of 58 patients with TP53 sequencing results available). With a median follow-up of 49·8 months (range, 0·1-95·9), median progression-free survival was not reached. Progression-free survival rate and overall survival rate estimates at four years were 79% and 88%, respectively. Overall response rate was 93%, including complete response in 39% of patients. No new safety signals were identified in this analysis. Forty-six percent of patients remained on ibrutinib treatment at last follow-up. With median follow-up of four years (up to eight years), results from this large, pooled, multi-study data set suggest promising long-term outcomes of first-line ibrutinib-based therapy in patients with TP53 aberrations. Registered at ClinicalTrials.gov (NCT01500733, NCT01722487, NCT02264574 and NCT02048813)

Taselisib (GDC-0032), a Potent -Sparing Small Molecule Inhibitor of PI3K, Radiosensitizes Head and Neck Squamous Carcinomas Containing Activating PIK3CA Alterations

Activating PIK3CA genomic alterations are frequent in head and neck squamous cell carcinoma (HNSCC), and there is an association between phosphoinositide 3-kinase (PI3K) signaling and radioresistance. Hence, we investigated the therapeutic efficacy of inhibiting PI3K with GDC-0032, a PI3K inhibitor with potent activity against p110α, in combination with radiation in HNSCC

Radiation-induced death: Characterization of a novel mechanism

Astronauts traveling to Mars will be exposed to Solar Particle Events (SPEs) during their missions. Modeling these large SPEs has led to the knowledge that such SPEs can result in significant doses of radiation that could be deleterious to astronaut health and mission success. Since the bombings of Hiroshima and Nagasaki in 1945, an emphasis has been placed on understanding the consequences of ionizing radiation. At the lowest doses of radiation known to be capable of killing mammals, radiation-induced death is hypothesized to occur due to the hematopoietic syndrome through a severe loss of cells in the hematopoietic system that potentially results in infection (from the loss of white blood cells) and bleeding (from the loss of platelets). The lethal dose of radiation to 50% of the population, referred to as the LD50, for the Hiroshima and Nagasaki casualties is calculated to be ∼2.5 Gy. Certain animals have LD50 values as low as 1.4 Gy (cattle) and as high as 13.4 Gy (mice). The differences in the LD 50 between species have yet to be explained. In these studies, animals were exposed to doses of radiation near the LD50 and monitored for parameters as part of hemostasis and the hematopoietic system. This work will focus on the mechanism of radiation-induced death by evaluating both the hematopoietic system and hemostasis (primary and secondary). Radiation exposure resulted in activation of blood clotting parameters within hours of exposure; this activation persisted, and became more abnormal over time. The results presented here suggest that the cell killing effects of radiation in white blood cells or platelets may not be responsible for death in mammals at the LD50, but, in fact, are due to disseminated intravascular coagulation (DIC). We hypothesize that the mechanism by which mammals die from low doses of radiation is determined by their propensity to develop DIC, which determines their LD50. These results suggest a novel mechanism to describe the mechanism by which humans die at the LD50 and provide insight into the variable LD50 values observed among mammals. These studies will provide new direction for our understanding and treatment of radiation exposure

Leukocyte activity is altered in a ground based murine model of microgravity and proton radiation exposure.

Immune system adaptation during spaceflight is a concern in space medicine. Decreased circulating leukocytes observed during and after space flight infer suppressed immune responses and susceptibility to infection. The microgravity aspect of the space environment has been simulated on Earth to study adverse biological effects in astronauts. In this report, the hindlimb unloading (HU) model was employed to investigate the combined effects of solar particle event-like proton radiation and simulated microgravity on immune cell parameters including lymphocyte subtype populations and activity. Lymphocytes are a type of white blood cell critical for adaptive immune responses and T lymphocytes are regulators of cell-mediated immunity, controlling the entire immune response. Mice were suspended prior to and after proton radiation exposure (2 Gy dose) and total leukocyte numbers and splenic lymphocyte functionality were evaluated on days 4 or 21 after combined HU and radiation exposure. Total white blood cell (WBC), lymphocyte, neutrophil, and monocyte counts are reduced by approximately 65%, 70%, 55%, and 70%, respectively, compared to the non-treated control group at 4 days after combined exposure. Splenic lymphocyte subpopulations are altered at both time points investigated. At 21 days post-exposure to combined HU and proton radiation, T cell activation and proliferation were assessed in isolated lymphocytes. Cell surface expression of the Early Activation Marker, CD69, is decreased by 30% in the combined treatment group, compared to the non-treated control group and cell proliferation was suppressed by approximately 50%, compared to the non-treated control group. These findings reveal that the combined stressors (HU and proton radiation exposure) result in decreased leukocyte numbers and function, which could contribute to immune system dysfunction in crew members. This investigation is one of the first to report on combined proton radiation and simulated microgravity effects on hematopoietic, specifically immune cells

Distinct vascular genomic response of proton and gamma radiation-A pilot investigation.

The cardiovascular biology of proton radiotherapy is not well understood. We aimed to compare the genomic dose-response to proton and gamma radiation of the mouse aorta to assess whether their vascular effects may diverge. We performed comparative RNA sequencing of the aorta following (4 hrs) total-body proton and gamma irradiation (0.5-200 cGy whole body dose, 10 dose levels) of conscious mice. A trend analysis identified genes that showed a dose response. While fewer genes were dose-responsive to proton than gamma radiation (29 vs. 194 genes; q-value ≤ 0.1), the magnitude of the effect was greater. Highly responsive genes were enriched for radiation response pathways (DNA damage, apoptosis, cellular stress and inflammation; p-value ≤ 0.01). Gamma, but not proton radiation induced additionally genes in vasculature specific pathways. Genes responsive to both radiation types showed almost perfectly superimposable dose-response relationships. Despite the activation of canonical radiation response pathways by both radiation types, we detected marked differences in the genomic response of the murine aorta. Models of cardiovascular risk based on photon radiation may not accurately predict the risk associated with proton radiation

Long-term efficacy of first-line ibrutinib treatment for chronic lymphocytic leukaemia in patients with TP53 aberrations: a pooled analysis from four clinical trials.

TP53 aberrations [del(17p) or TP53 mutation] predict poor survival with chemoimmunotherapy in patients with chronic lymphocytic leukaemia (CLL). We evaluated long-term efficacy and safety of first-line ibrutinib-based therapy in patients with CLL bearing TP53 aberrations in a pooled analysis across four studies: PCYC-1122e, RESONATE-2 (PCYC-1115/16), iLLUMINATE (PCYC-1130) and ECOG-ACRIN E1912. The pooled analysis included 89 patients with TP53 aberrations receiving first-line treatment with single-agent ibrutinib (n = 45) or ibrutinib in combination with an anti-CD20 antibody (n = 44). All 89 patients had del(17p) (53% of 89 patients) and/or TP53 mutation (91% of 58 patients with TP53 sequencing results available). With a median follow-up of 49·8 months (range, 0·1-95·9), median progression-free survival was not reached. Progression-free survival rate and overall survival rate estimates at four years were 79% and 88%, respectively. Overall response rate was 93%, including complete response in 39% of patients. No new safety signals were identified in this analysis. Forty-six percent of patients remained on ibrutinib treatment at last follow-up. With median follow-up of four years (up to eight years), results from this large, pooled, multi-study data set suggest promising long-term outcomes of first-line ibrutinib-based therapy in patients with TP53 aberrations. Registered at ClinicalTrials.gov (NCT01500733, NCT01722487, NCT02264574 and NCT02048813)

Total blood cell counts are decreased in the irradiated (2 Gy) groups +/− HU treatment WBCs (A) and lymphocytes (B) at 4 days post-proton radiation exposure are significantly decreased, compared to the No treatment group (*).

<p>The WBC and lymphocyte results indicated statistically significant differences between the 2 Gy + HU group and the No treatment group (*), as well as between the 2 Gy + HU group and the HU group (#). Average counts +/− SD are expressed as a fraction of the control, n = 3–5. The neutrophil count at 4 days post-proton radiation exposure + HU treatment are significantly decreased, compared to the neutrophil counts observed for the No treatment group (*) and the HU group (#). HU treatment results in a statistically significant increase in neutrophil counts, compared to the No treatment group (*) (C); however, the differences between the neutrophil counts for the 2 Gy group are not statistically significant when compared to the neutrophil counts from the mice in the No treatment group. Monocytes are decreased in the combined treatment group (2 Gy + HU) compared to the No treatment group (*) (D).</p