Cyrus V. Hedvat

Adults with relapsed B cell acute lymphoblastic leukemia (B-ALL) have a dismal prognosis. Only those patients able to achieve a second remission with no minimal residual disease (MRD) have a hope for long-term survival in the context of a subsequent allogeneic hematopoietic stem cell transplantation (allo-HSCT). We have treated five relapsed B-ALL subjects with autologous T cells expressing a CD19-specific CD28/CD3ζ second-generation dual-signaling chimeric antigen receptor (CAR) termed 19-28z. All patients with persistent morphological disease or MRD(+) disease upon T cell infusion demonstrated rapid tumor eradication and achieved MRD(-) complete remissions as assessed by deep sequencing polymerase chain reaction. Therapy was well tolerated, although significant cytokine elevations, specifically observed in those patients with morphologic evidence of disease at the time of treatment, required lymphotoxic steroid therapy to ameliorate cytokine-mediated toxicities. Indeed, cytokine elevations directly correlated to tumor burden at the time of CAR-modified T cell infusions. Tumor cells from one patient with relapsed disease after CAR-modified T cell therapy, who was ineligible for additional allo-HSCT or T cell therapy, exhibited persistent expression of CD19 and sensitivity to autologous 19-28z T cell-mediated cytotoxicity, which suggests potential clinical benefit of additional CAR-modified T cell infusions. These results demonstrate the marked antitumor efficacy of 19-28z CAR-modified T cells in patients with relapsed/refractory B-ALL and the reliability of this therapy to induce profound molecular remissions, forming a highly effective bridge to potentially curative therapy with subsequent allo-HSCT.

Disease alleles that activate signal transduction are common in myeloid malignancies; however, there are additional unidentified mutations that contribute to myeloid transformation. Based on the recent identification of TET2 mutations, we evaluated the mutational status of TET1, TET2, and TET3 in myeloproliferative neoplasms (MPNs), chronic myelomonocytic leukemia (CMML), and acute myeloid leukemia (AML). Sequencing of TET2 in 408 paired tumor/normal samples distinguished between 68 somatic mutations and 6 novel single nucleotide polymorphisms and identified TET2 mutations in MPN (27 of 354, 7.6%), CMML (29 of 69, 42%), AML (11 of 91, 12%), and M7 AML (1 of 28, 3.6%) samples. We did not identify somatic TET1 or TET3 mutations or TET2 promoter hypermethylation in MPNs. TET2 mutations did not cluster in genetically defined MPN, CMML, or AML subsets but were associated with decreased overall survival in AML (P = .029). These data indicate that TET2 mutations are observed in different myeloid malignancies and may be important in AML prognosis.

PURPOSE: The p63 gene, located on chromosome 3q27-28, is a member of the p53 gene family. The product encoded by the p63 gene has been reported to be essential for normal development. EXPERIMENTAL DESIGN: In this study, we examined the expression pattern of p63 in human normal and tumor tissues by immunohistochemistry using a monoclonal antibody (clone 4A4) that recognizes all p63 splice variants, and by reverse transcription-PCR using isoform-specific primers. RESULTS: We found that p63 expression was restricted to the nucleus, with a nucleoplasmic pattern. We also observed that the expression was restricted to epithelial cells of stratified epithelia, such as skin, esophagus, exocervix, tonsil, and bladder, and to certain subpopulations of basal cells in glandular structures of prostate and breast, as well as in bronchi. Consistent with the phenotype observed in normal tissues, we found that p63 is expressed predominantly in basal cell and squamous cell carcinomas, as well as transitional cell carcinomas, but not in adenocarcinomas, including those of breast and prostate. Interestingly, thymomas expressed high levels of p63. Moreover, a subset of non-Hodgkin's lymphoma was also found to express p63. Using isoform-specific reverse transcription-PCR, we found that thymomas express all isoforms of p63, whereas the non-Hodgkin's lymphoma tended to express the transactivation-competent isoforms. We did not detect p63 expression in a variety of endocrine tumors, germ cell neoplasms, or melanomas. Additionally, soft tissue sarcomas were also found to have undetectable p63 levels. CONCLUSIONS: Our data support a role for p63 in squamous and transitional cell carcinomas, as well as certain lymphomas and thymomas.