Chad Tang

CD47, a "don't eat me" signal for phagocytic cells, is expressed on the surface of all human solid tumor cells. Analysis of patient tumor and matched adjacent normal (nontumor) tissue revealed that CD47 is overexpressed on cancer cells. CD47 mRNA expression levels correlated with a decreased probability of survival for multiple types of cancer. CD47 is a ligand for SIRPα, a protein expressed on macrophages and dendritic cells. In vitro, blockade of CD47 signaling using targeted monoclonal antibodies enabled macrophage phagocytosis of tumor cells that were otherwise protected. Administration of anti-CD47 antibodies inhibited tumor growth in orthotopic immunodeficient mouse xenotransplantation models established with patient tumor cells and increased the survival of the mice over time. Anti-CD47 antibody therapy initiated on larger tumors inhibited tumor growth and prevented or treated metastasis, but initiation of the therapy on smaller tumors was potentially curative. The safety and efficacy of targeting CD47 was further tested and validated in immune competent hosts using an orthotopic mouse breast cancer model. These results suggest all human solid tumor cells require CD47 expression to suppress phagocytic innate immune surveillance and elimination. These data, taken together with similar findings with other human neoplasms, show that CD47 is a commonly expressed molecule on all cancers, its function to block phagocytosis is known, and blockade of its function leads to tumor cell phagocytosis and elimination. CD47 is therefore a validated target for cancer therapies.

PURPOSE Our previously published findings reported that local consolidative therapy (LCT) with radiotherapy or surgery improved progression-free survival (PFS) and delayed new disease in patients with oligometastatic non–small-cell lung cancer (NSCLC) that did not progress after front-line systemic therapy. Herein, we present the longer-term overall survival (OS) results accompanied by additional secondary end points. PATIENTS AND METHODS This multicenter, randomized, phase II trial enrolled patients with stage IV NSCLC, three or fewer metastases, and no progression at 3 or more months after front-line systemic therapy. Patients were randomly assigned (1:1) to maintenance therapy or observation (MT/O) or to LCT to all active disease sites. The primary end point was PFS; secondary end points were OS, toxicity, and the appearance of new lesions. All analyses were two sided, and P values less than .10 were deemed significant. RESULTS The Data Safety and Monitoring Board recommended early trial closure after 49 patients were randomly assigned because of a significant PFS benefit in the LCT arm. With an updated median follow-up time of 38.8 months (range, 28.3 to 61.4 months), the PFS benefit was durable (median, 14.2 months [95% CI, 7.4 to 23.1 months] with LCT v 4.4 months [95% CI, 2.2 to 8.3 months] with MT/O; P = .022). We also found an OS benefit in the LCT arm (median, 41.2 months [95% CI, 18.9 months to not reached] with LCT v 17.0 months [95% CI, 10.1 to 39.8 months] with MT/O; P = .017). No additional grade 3 or greater toxicities were observed. Survival after progression was longer in the LCT group (37.6 months with LCT v 9.4 months with MT/O; P = .034). Of the 20 patients who experienced progression in the MT/O arm, nine received LCT to all lesions after progression, and the median OS was 17 months (95% CI, 7.8 months to not reached). CONCLUSION In patients with oligometastatic NSCLC that did not progress after front-line systemic therapy, LCT prolonged PFS and OS relative to MT/O.