Characterization of sentinel node-derived antibodies from breast cancer patients

A cocktail of polyclonal affinity enriched antibodies against melanoma mutations increases binding and inhibits tumor growth

BACKGROUND

Antibodies that target a single tumor antigen fail to cure stage IV cancer patients due to tumor heterogeneity and variable expression of antigen. Tumor cells with insufficient binding of antibody will not undergo antibody induced cytotoxicity. We describe targeting multiple tumor-specific antigens that resulted in homogeneous dense binding to mouse melanoma cells and significant tumor growth inhibition.

METHODS

Surface-related tumor-specific mutations on B16-F10 cells were identified. Peptides containing the single amino acid mutation were synthesized for 9 different neoantigens. Rabbits were vaccinated with each of these peptides and high affinity polyclonal antibodies to each peptide were obtained. The 9 antibodies were combined as a cocktail and mice with implanted B16-F10 cells were treated with and without PD1 inhibitor.

RESULTS

Even a single dose of the antibody cocktail inhibited tumor growth and prolonged survival. PD1 inhibitor alone had little effect on tumor growth. The antibody cocktail plus PD1 inhibition increased tumor response and 4 doses of the cocktail completely prevented tumor growth in 50% of the mice. Complete responses were durable. The complete responders were highly resistant to tumor re-challenge at 6 months. No adverse events were identified in the antibody treated mice.

CONCLUSIONS

Multiple tumor-specific cell surface-related neoantigens were abundant in B16-F10 cells. Antibodies to 9 of these neoantigens had variable binding but when combined had dense homogeneous binding. Even one dose of this cocktail of 9 antibodies improved survival and when multiple doses were combined with PD1 inhibition 50% of the mice were rendered permanently tumor free.

Effects of human umbilical cord mesenchymal stem cells on co-cultured ovarian carcinoma cells

Ovarian carcinoma is mainly treated by surgery aided by chemotherapy. If supplemented by stem cells treatment, its recurrence rate and mortality rate will be decreased. This is a new therapy. In this study, ovarian cancer cells were cultured together with umbilical cord mesenchymal stem cells (UCMSCs), and the interactions between them were observed. The results showed that the survival rates of UCMSCs increased to 83.8 ± 2.2% from 56.5 ± 5.5%, and the survival rates of ovarian cancer cells decreased to 16.2 ± 2.2% from 43.5 ± 5.5% with the progression of the cultural time from 24 to 96 hr. There was a significant difference between them (p < .05). It revealed that UCMSCs could inhibit the proliferation of ovarian cancer cells.

Sentinel lymph node B cells can predict disease-free survival in breast cancer patients

Tumor invasion into draining lymph nodes, especially sentinel lymph nodes (SLNs), is a key determinant of prognosis and treatment in breast cancer as part of the TNM staging system. Using multicolor histology and quantitative image analysis, we quantified immune cells within SLNs from a discovery cohort of 76 breast cancer patients. We found statistically more in situ CD3⁺ T cells in tumor negative vs. tumor positive nodes (mean of 8878 vs. 6704, respectively, p = 0.006), but no statistical difference in CD20⁺ B cells or CD1a⁺ dendritic cells. In univariate analysis, a reduced hazard was seen with a unit increase in log CD3 with HR 0.49 (95% CI 0.30–0.80) and log CD20 with HR 0.37 (95% CI 0.22–0.62). In multivariate analysis, log CD20 remained significant with HR 0.42 (95% CI 0.25–0.69). When restricted to SLN tumor negative patients, increased log CD20 was still associated with improved DFS (HR = 0.26, 95% CI 0.08–0.90). The CD20 results were validated in a separate cohort of 21 patients (n = 11 good outcome, n = 10 poor outcome) with SLN negative triple-negative breast cancer (TNBC) (“good” mean of 7011 vs. “poor” mean of 4656, p = 0.002). Our study demonstrates that analysis of immune cells within SLNs, regardless of tumor invasion status, may provide additional prognostic information, and highlights B cells within SLNs as important in preventing future recurrence.

B cells within the tumor-draining lymph nodes may have an important biological role in preventing relapse of breast cancer. A team led by Peter Lee from City of Hope in Duarte, California, USA, quantified the levels of three populations of immune cells—T cells, B cells and dendritic cells—within sentinel lymph nodes biopsied from a cohort of 76 patients. They found that larger numbers of T cells and B cells were both linked to longer progression-free survival in the women. However, after statistically accounting for correlations between the two immune cell types, the researchers concluded that B cells had the dominant beneficial effect on survival times. They validated the finding that high B-cell counts are a prognostic indicator of better outcomes in a separate cohort of 21 women with triple-negative breast cancer.