Phase I study of tremelimumab (CP-675 206) plus PF-3512676 (CPG 7909) in patients with melanoma or advanced solid tumours.

BACKGROUND: Tremelimumab, a fully human cytotoxic T-lymphocyte antigen 4 monoclonal antibody, and PF-3512676, a Toll-like receptor-9 agonist, are targeted immune modulators that elicit durable single-agent antitumour activity in advanced cancer. METHODS: To determine the maximum tolerated dose (MTD) of these agents combined during this phase I study, patients received intravenous tremelimumab (6.0, 10.0, or 15.0 mg kg(-1)) every 12 weeks plus subcutaneous PF-3512676 (0.05, 0.10, or 0.15 mg kg(-1)) weekly. Primary end points were safety and tolerability; secondary end points included pharmacokinetics and antitumour activity. RESULTS: Twenty-one patients with stage IV melanoma (n=17) or advanced solid tumours (n=4) were enrolled. Injection-site reactions (n=21; 100%), influenza-like illness (n=18; 86%), and diarrhoea (n=13; 62%) were the most common treatment-related adverse events (TAEs). Grade ≥3 TAEs were reported (n=7; 33%). Dose-limiting toxicities (prespecified 6-week observation) occurred in one of the six patients in the 10 mg kg(-1) tremelimumab plus 0.05 mg kg(-1) PF-3512676 cohort (grade 3 hypothalamopituitary disorder) and two of the six patients in the 15 mg kg(-1) tremelimumab plus 0.05 mg kg(-1) PF-3512676 cohort (grade 3 diarrhoea). Consequently, 15 mg kg(-1) tremelimumab plus 0.05 mg kg(-1) PF-3512676 exceeded the MTD. Two melanoma patients achieved durable (≥170 days) partial response. No human antihuman antibody responses to tremelimumab were observed. CONCLUSION: Weekly PF-3512676 (≤0.15 mg kg(-1)) plus tremelimumab (≤10 mg kg(-1) every 12 weeks) was tolerable.

A phase III randomized study of gemcitabine and cisplatin with or without PF-3512676 (TLR9 agonist) as first-line treatment of advanced non-small-cell lung cancer.

BACKGROUND: This open-label phase III study assessed the addition of Toll-like receptor 9-activating oligodeoxynucleotide PF-3512676 to gemcitabine/cisplatin chemotherapy in patients with non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: Chemotherapy-naive patients with stage IIIB or IV NSCLC were randomized (1:1) to receive six or fewer 3-week cycles of i.v. gemcitabine (1250 mg/m2 on days 1 and 8) and cisplatin alone (75 mg/m2 on day 1, control arm) or combined with s.c. PF-3512676 0.2 mg/kg on days 8 and 15 of each chemotherapy cycle and weekly thereafter until progression or unacceptable toxicity (experimental arm). No crossover was planned. The primary end point was overall survival (OS). RESULTS: A total of 839 patients were randomized. Baseline demographics were well balanced. Median OS (11.0 versus 10.7 months; P=0.98) and median progression-free survival (PFS) (both 5.1 months) were similar between groups. Grade≥3 hematologic adverse events (AEs), injection-site reactions, and influenza-like symptoms were more frequently reported among patients receiving PF-3512676. At the first-interim analysis, the Data Safety Monitoring Committee recommended study discontinuation. Administration of PF-3512676 was halted based on efficacy futility and increased grade≥3 AEs (experimental arm). CONCLUSIONS: Addition of PF-3512676 to gemcitabine/cisplatin chemotherapy did not improve OS or PFS but did increase toxicity.

Reversible resistance to apoptosis in cutaneous T cell lymphoma.

Mycosis fungoides and its leukemic variant, Sézary syndrome, represent the most common forms of cutaneous T cell lymphomas (CTCL). These disorders are clonal neoplasms characterized by the progressive accumulation of cells that resemble activated/memory CD4+ T cells. Unlike their normal counterparts, these malignant lymphocytes have prolonged life spans and are resistant to dying following treatment with most chemotherapeutic agents. This suggests that CTCL undergo abnormal programmed cell death; however, data regarding apoptotic defects in CTCL are limited. Regulation of apoptosis in lymphocytes that regularly undergo clonal expansion is necessarily complex and will be reviewed here. Clonally expanded lymphocytes rely primarily on Fas-mediated pathways to initiate apoptosis. Factors leading to the resistance of apoptosis in CTCL and new therapeutic approaches for reversing this resistance will be discussed, including the important role that the Fas death pathway may play in the pathogenesis and treatment of CTCL.

Unusual childhood extramedullary hematologic malignancy with natural killer cell properties that contains tropomyosin 4--anaplastic lymphoma kinase gene fusion.

This report describes an unusual extramedullary hematologic malignancy in an 18-month-old child who presented with a capillary leak syndrome that evolved into hyperleukocytosis with malignant cells. The circulating tumor cells did not express an antigen profile typical of any subtype of leukemia commonly observed in children. Tumor cells were CD3(-)/CD56(+); had germline TCR genes; and strongly expressed CD30, epithelial membrane antigen, and anaplastic lymphoma kinase (ALK) consistent with a null cell anaplastic large cell lymphoma (ALCL). The malignant cells contained a t(2;19)(p23;p13.1) that interrupted ALK and translocated it to the der(19). Reverse transcriptase-polymerase chain reaction and nucleotide sequence analysis revealed fusion of ALK to tropomyosin 4, an ALK fusion partner not described previously in hematologic malignancies. The clinical presentation and phenotypic features of this malignancy were not typical for ALCL because tumor cells expressed both myeloid (CD13, CD33, HLA-DR) and natural killer (NK) cell antigens. The neoplastic cells most resembled NK cells because in addition to being CD3(-)/CD56(+) with germline TCR genes, these cells were CD25(+)/CD122(+)/granzyme B(+) and possessed the functional properties of immature NK cells. The unusual clinical presentation, immunophenotype, and functional properties of these neoplastic cells suggest that this malignancy may be derived from the putative myeloid-NK precursor cell. Furthermore co-expression of NK and ALCL features supports the concept that a minority of null-ALCL may be derived from NK cells and expands the spectrum of phenotypes that can be seen in tumors produced by ALK fusion proteins. (Blood. 2001;98:1209-1216)

Adenovirus-mediated expression of Fas ligand induces apoptosis of human prostate cancer cells.

Several laboratories have reported on the apoptotic potentials of human prostate cancer (PC) cell lines in response to crosslinking of Fas (CD95/APO-1) with agonistic anti-Fas antibodies. We have re-evaluated the apoptotic potentials of seven human PC cell lines using the natural Fas ligand (FasL) in place of agonistic antibody. First, PC cell lines were tested in a standard cytotoxicity assay with a transfected cell line that stably expresses human FasL. Next, we developed an adenoviral expression system employing 293 cells that stably express crmA, a poxvirus inhibitor of apoptosis, to analyze the effects of FasL when expressed internally by the PC cell lines. Our data suggest that the apoptotic potentials of these cell lines were greatly underestimated in previous studies utilizing agonistic anti-Fas antibodies. Lastly, adenoviral-mediated expression of FasL prevented growth and induced regression of two human PC cell lines in immunodeficient mice. These preliminary in vivo results suggest a potential use for adenovirus encoding FasL as a gene therapy for PC.

Adenoviral-mediated gene transfer in lymphocytes.

Although adenovirus can infect a wide range of cell types, lymphocytes are not generally susceptible to adenovirus infection, in part because of the absence of the expression of the cellular receptor for the adenoviral fiber protein. The cellular receptor for adenovirus and coxsackievirus (CAR) recently was cloned and shown to mediate adenoviral entry by interaction with the viral fiber protein. We show that the ectopic expression of CAR in various lymphocyte cell lines, which are almost completely resistant to adenovirus infection, is sufficient to facilitate the efficient transduction of these cells by recombinant adenoviruses. Furthermore, this property of CAR does not require its cytoplasmic domain, consistent with the idea that CAR primarily serves as a high affinity binding site for the adenoviral fiber protein, and that viral entry is mediated by interaction of the viral penton base proteins with cellular integrins. As a demonstration of their functional utility, we used CAR-expressing lymphocytes transduced with an adenovirus expressing Fas ligand to efficiently kill Fas receptor-expressing tumor cells. The ability to efficiently manipulate gene expression in lymphocyte cells by using adenovirus vectors should facilitate the functional characterization of pathways affecting lymphocyte physiology.