Heterogeneity of immune status in patient-derived malignant pleural effusion and ascites: Relationship to the ex-vivo efficacy of a HER2-targeted tri-specific antibody and a novel cytokine fusion protein.

e13000 Background: Malignant pleural effusion (MPE) and malignant ascites (MA) are common complications of malignant tumors, often indicating that the malignant tumors have reached an advanced stage, leading to a shorter survival. Historical studies have shown that the effusion or asities are deficient in innate immunity and/or adaptive immunity. It would be a high therapeutic value if the immune status (deficiency or exhaustion) in this tumor microenvironment can be corrected using innate and adaptive immune targeting molecules. Here we have studied the immune status of one MPE sample from an advanced Her2 positive breast cancer patient and one MA sample from an advanced ovarian cancer patient; and used a novel tri-specific molecule targeting Her2, macrophage and NK cell (IAMA-004) and a novel Fc-cytokine fusion protein (IAMA-005) to treat the cells from MPE or MA samples to determine the efficacy in the killings of tumor cells and the modulation of IFN-γ and Granzyme B levels. Methods: A pleural effusion sample from a 61-year-old female patient suffering from breast cancer lung metastasis and an ascitic fluid sample from a 58-year-old female patient with poorly differentiated advanced ovarian cancer were collected. The cells were immunophenotyped and treated with IAMA-004, IAMA-005, anti-PD1 or control. The killing of Her2 positive or EpCAM positive tumor cells and the levels of IFN-γ and Granzyme B were measured. Results: MPE immune status: NK cells, 6.47%; Macrophages, 2.11% (M1, 0.06%; M2, 0.33%); CD3 + T cells, 5.47%; CD4 + T cells, 2.93%; CD8 + T cells, 1.66%; Treg, not detectable. IAMA-004 and IAMA-005 enhanced the killing of Her2 positive tumor cells by ~30% and ~40% respectively; Herceptin plus TTI-622 was not able to enhance the tumor cell killing. In combination with nivolumab, IAMA-004 was able to enhance the Granzyme B and IFN-γ secretion significantly without enhancing the tumor cell killing. Ascites immune status: NK cells, 0.5%; macrophage, 10.74% (M1, 0.31%; M2 0.05%); CD3 + T cells, 5.98%; CD4 + T cells, 4.36%; CD8 + T cells, 0.97%; Treg, not detectable. While anti-PD1 antibody was not able to kill the tumor cells over the background, IAMA-004, IAMA-005 or Herceptin plus TTI-622 was able to enhance the tumor cell killing over the background more than 2.5-fold. Addition of anti-PD1 to IAMA-004 or IAMA-005 did not further increase the efficacy. The immune status of MPE being NK competent while MA being macrophage competent seems to determine the efficacy of the respective therapeutic molecules. Conclusions: Immune status from MPE or MA are heterogenous in both adaptive and innate immunity. Using combinations of innate immune targeting therapeutics and adaptive immune check point inhibitors may be able to correct the specific deficiency with precision and effectively treat these diseases.