We previously demonstrated that autologous natural killer (NK)-cell therapy after hematopoietic cell transplantation (HCT) is safe but does not provide an antitumor effect. We hypothesize that this is due to a lack of NK-cell inhibitory receptor mismatching with autologous tumor cells, which may be overcome by allogeneic NK-cell infusions. Here, we test haploidentical, related-donor NK-cell infusions in a nontransplantation setting to determine safety and in vivo NK-cell expansion. Two lower intensity outpatient immune suppressive regimens were tested: (1) low-dose cyclophosphamide and methylprednisolone and (2) fludarabine. A higher intensity inpatient regimen of high-dose cyclophosphamide and fludarabine (Hi-Cy/Flu) was tested in patients with poor-prognosis acute myeloid leukemia (AML). All patients received subcutaneous interleukin 2 (IL-2) after infusions. Patients who received lower intensity regimens showed transient persistence but no in vivo expansion of donor cells. In contrast, infusions after the more intense Hi-Cy/Flu resulted in a marked rise in endogenous IL-15, expansion of donor NK cells, and induction of complete hematologic remission in 5 of 19 poor-prognosis patients with AML. These findings suggest that haploidentical NK cells can persist and expand in vivo and may have a role in the treatment of selected malignancies used alone or as an adjunct to HCT.

No abstract

Purpose Combination PD-1/CTLA-4 blockade and dual BRAF/MEK inhibition have each shown significant clinical benefit in patients with BRAFV600 mutant metastatic melanoma, leading to broad regulatory approval. Little prospective data exist to guide the choice of either initial therapy or treatment sequence in this population. This study was conducted to determine which initial treatment or treatment sequence produced the best efficacy. Methods In a phase III trial, patients with treatment-naïve BRAFV600-mutant metastatic melanoma were randomized to receive either combination nivolumab/ipilimumab (Arm A) or dabrafenib/trametinib (Arm B) in Step 1, and at disease progression were enrolled in Step 2 receiving the alternate therapy, dabrafenib/trametinib (Arm C) or nivolumab/ipilimumab (Arm D). The primary endpoint was 2-year overall survival. Secondary endpoints were 3-year overall survival, objective response rate, response duration, progression-free survival, crossover feasibility and safety. Results 265 patients were enrolled with 73 going onto Step 2 (27 Arm C, 46 Arm D). The study was stopped early by the independent DSMC due to a clinically significant endpoint being achieved. The 2-year overall survival for those starting on Arm A was 71.8% (62.5, 79.1%) and Arm B 51.5% (41.7, 60.4%) (log-rank p=0.010). Step 1 progression-free survival favored Arm A (p=0.054). Objective response rates were: Arm A:46.0%; Arm B:43.0%; Arm C:47.8%; Arm D:29.6%. Median duration of response was not reached for Arm A and 12.7 months for Arm B (p<0.001). Crossover occurred in 52% of patients with documented disease progression. Grade >3 toxicities occurred with similar frequency between arms and regimen toxicity profiles were as anticipated. Conclusion Combination nivolumab/ipilimumab followed by BRAF and MEK inhibitor therapy, if necessary, should be the preferred treatment sequence for a large majority of patients.

Mono-ADP-ribosylation, a post-translational modification of proteins in which the ADP-ribose moiety of NAD is transferred to an acceptor amino acid, occurs in viruses, bacteria, and eukaryotic cells (1). The reaction is distinct from that catalyzed by poly(ADPribose) polymerase, a nuclear protein involved in DNA repair, cell differentiation, and the maintenance of chromatin structure (2). Among mono-ADP-ribosyltransferases, the bacterial toxins, cholera toxin, pertussis toxin, diphtheria toxin, and Pseudomonas aeruginosa exotoxin A are the best characterized in molecular structure, function, and substrate specificity (reviewed in Ref. 1). Mono-ADP-ribosyltransferases from mammalian and avian cells have been cloned and characterized, and specific target proteins have been identified (3,4). In lymphocytes, a glycosylphosphatidylinositol (GPI) 1 -anchored transferase appears to be involved in immune modulation, whereas other isoforms in lymphocytes (5) and chicken heterophil granules (6) are membrane-associated but appear to be processed for secretion. Further, ADP-ribosyltransferases have been purified from brain, and data from several independent laboratories demonstrate that ADP-ribosylation is involved in neuronal function (7,8). Deduced amino acid sequences of the vertebrate ADP-ribosyltransferases have similarities to those of viral and bacterial toxin transferases (9, 10) in regions that form, in part, an active site cleft, consistent with a common mechanism of NAD binding and ADP-ribose transfer (9).The majority of the eukaryotic enzymes are arginine-specific transferases. ADP-ribosylation of arginine appears to be a reversible process; free arginine can be regenerated in ADP-ribosylated proteins by ADP-ribosylarginine hydrolases (1). ADP-ribosylarginine hydrolase activity was detected in the soluble fraction of turkey erythrocytes, cultured mouse cells, and rat skeletal muscle with deduced amino acid sequences known for rat, mouse, and human brain ADP-ribosylarginine hydrolases (11,12).ADP-ribosylation of cysteine was reported in bovine erythrocytes (13), and an NAD:cysteine ADP-ribosyltransferase that modified G␣ i was purified from human erythrocyte and platelet membranes (14). Consistent with this, ADP-ribosylcysteine linkages were detected in rat liver plasma membranes (15). ADP-ribosylation of cysteine can, however, occur nonenzymatically via the reaction of ADP-ribose, generated from NAD by NAD glycohydrolases, with cysteine to form an ADP-ribosylthiazolidine, a linkage distinct from the thioglycoside formed by pertussis toxin (PT)-catalyzed ADP-ribosylation of a cysteine in the heterotrimeric guanine nucleotide-binding (G) proteins (16). Nonenzymatic ADP-ribosylation of cysteine in proteins, however, yielded a product with the same chemical sensitivity as the linkage formed by PT (17). Based on these data, the ADP-ribose-cysteine produced by the human erythrocyte enzyme may have been generated nonenzymatically from free ADP-ribose. Because nitric oxide (NO) induced the noncovalent binding of the ent...