BACKGROUND Programmed death 1 (PD-1) protein, a T-cell coinhibitory receptor, and one of its ligands, PD-L1, play a pivotal role in the ability of tumor cells to evade the host’s immune system. Blockade of interactions between PD-1 and PD-L1 enhances immune function in vitro and mediates antitumor activity in preclinical models. METHODS In this multicenter phase 1 trial, we administered intravenous anti–PD-L1 antibody (at escalating doses ranging from 0.3 to 10 mg per kilogram of body weight) to patients with selected advanced cancers. Anti–PD-L1 antibody was administered every 14 days in 6-week cycles for up to 16 cycles or until the patient had a complete response or confirmed disease progression. RESULTS As of February 24, 2012, a total of 207 patients — 75 with non–small-cell lung cancer, 55 with melanoma, 18 with colorectal cancer, 17 with renal-cell cancer, 17 with ovarian cancer, 14 with pancreatic cancer, 7 with gastric cancer, and 4 with breast cancer — had received anti–PD-L1 antibody. The median duration of therapy was 12 weeks (range, 2 to 111). Grade 3 or 4 toxic effects that investigators considered to be related to treatment occurred in 9% of patients. Among patients with a response that could be evaluated, an objective response (a complete or partial response) was observed in 9 of 52 patients with melanoma, 2 of 17 with renal-cell cancer, 5 of 49 with non–small-cell lung cancer, and 1 of 17 with ovarian cancer. Responses lasted for 1 year or more in 8 of 16 patients with at least 1 year of follow-up. CONCLUSIONS Antibody-mediated blockade of PD-L1 induced durable tumor regression (objective response rate of 6 to 17%) and prolonged stabilization of disease (rates of 12 to 41% at 24 weeks) in patients with advanced cancers, including non–small-cell lung cancer, melanoma, and renal-cell cancer. (Funded by Bristol-Myers Squibb and others; ClinicalTrials.gov number, NCT00729664.)

Background-Malignant cells of classical Hodgkin lymphoma (cHL) are characterised by genetic alterations at the 9p24·1 locus. This leads to overexpression of the programmed death 1 (PD-1) ligands and enables tumour cells to evade immune surveillance. A phase 1b study showed that nivolumab, a PD-1-blocking antibody, produced a high response rate in patients with relapsed and refractory cHL, with an acceptable safety profile. This phase 2 study assessed the clinical benefit of nivolumab monotherapy in patients with cHL after autologous stem-cell transplantation and brentuximab vedotin failure.

Clinical experimental stroke induces injurious local brain inflammation. However, effects on the peripheral immune system have not been well characterized. We quantified mRNA and protein levels for cytokines, chemokines, and chemokine receptors (CCR) in brain, spinal cord, peripheral lymphoid organs (spleen, lymph node, blood, and cultured mononuclear cells from these sources), and blood plasma after reversible middle cerebral artery occlusion (MCAO) or sham treatment in male C57BL/6 mice. Middle cerebral artery occlusion induced a complex, but organ specific, pattern of inflammatory factors in the periphery. At both 6 and 22 h after MCAO, activated spleen cells from stroke-injured mice secreted significantly enhanced levels of TNF-a, IFN-c, IL-6, MCP-1, and IL-2. Unstimulated splenocytes expressed increased chemokines and CCR, including MIP-2 and CCR2, CCR7 & CCR8 at 6 h; and MIP-2, IP-10, and CCR1 & CCR2 at 22 h. Also at 22 h, T cells from blood and lymph nodes secreted increased levels of inflammatory cytokines after activation. As expected, there were striking proinflammatory changes in postischemic brain. In contrast, spinal cord displayed suppression of all mediators, suggesting a compensatory response to intracranial events. These data show for the first time that focal cerebral ischemia results in dynamic and widespread activation of inflammatory cytokines, chemokines, and CCR in the peripheral immune system.

Induction of stroke not only produces local ischemia and brain damage, but also has profound effects on peripheral immune responses. In the current study, we evaluated effects on spleen and blood cells 4 days after stroke induction. Surprisingly, there was a less inflammatory cytokine profile in the middle cerebral artery occlusion-affected right brain hemisphere at 96 h compared with earlier time points. Moreover, our results demonstrate that stroke leads to splenic atrophy characterized by a reduction in organ size, a drastic loss of splenocyte numbers, and induction of annexin V+ and TUNEL+ cells within the spleen that are in the late stages of apoptosis. The consequence of this process was to reduce T cell proliferation responses and secretion of inflammatory cytokines, resulting in a state of profound immunosuppression. These changes produced a drastic reduction in B cell numbers in spleen and blood, and a novel increase in CD4+FoxP3+ regulatory T cells. Moreover, we detected a striking increase in the percentage of nonapoptotic CD11b+ VLA-4-negative macrophages/monocytes in blood. Immunosuppression in response to brain injury may account for the reduction of inflammatory factors in the stroke-affected brain, but also potentially could curtail protective immune responses in the periphery. These findings provide new evidence to support the contention that damage to the brain caused by cerebral ischemia provides a powerful negative signal to the peripheral immune system that ultimately induces a drastic state of immunosuppression caused by cell death as well as an increased presence of CD4+FoxP3+ regulatory T cells.

Stroke induction in immunologically competent mice not only produces local ischemia and brain damage, but also induces early inflammatory changes in brain and peripheral immune responses. Although immune elements clearly are activated after brain vascular occlusion, the relative contribution of T and B lymphocytes to the developing lesion has not been quantified. We evaluated effects 22 h after middle cerebral artery occlusion (90 mins) on histologic injury and peripheral immune activation in severe combined immunodeficient (SCID) mice lacking T and B cells. Cortical and total infarct volumes were strikingly reduced in male SCID mice (n = 14, 3364% of contralateral cortex, n = 10, 5263% of contralateral hemisphere) versus immunologically intact C57BL/6 mice (wild type, n = 9, 5765% of contralateral cortex, 5764% of contralateral hemisphere) (P < 0.01). Striatal infarction was not altered (7767% of contralateral striatum in SCID, 8467% in wild type), suggesting that the core of the evolving ischemic lesion was not impacted by lack of T and B cells. As expected, inflammatory factors from immune cells in ischemic SCID brains were essentially absent, with the exception of interleukin-1b increase in both SCID and wild type tissue. Spleen cell numbers were low in SCID mice, but were further reduced 22 h after stroke, with substantial reduction in most inflammatory factors except for increased expression of interferon-c and macrophage inflammatory protein (MIP)-2. These data quantify the damaging effect of T and B lymphocytes on early, evolving ischemic brain injury, and further implicate interleukin-1b in brain and interferon-c and MIP-2 in spleen as inflammatory factors produced by cells other than T and B cells.