Article Figures & Data
Figures
- Fig. 1
The combination of local RT and anti-CTLA-4 mAb 9H10 extends the survival of mice bearing the nonimmunogenic 4T1 carcinoma. Treatment was started on day 13 after s.c. inoculation with the 4T1 mammary carcinoma in the flank. RT was delivered by a single dose of 12 Gy to the s.c. tumors. Antibodies were given i.p. 1, 4, and 7 days after RT. Data are from two combined experiments (A). Tumor growth delay by RT. Mice received control hamster IgG (IgG, ▵, n = 11), 9H10 (▴, n = 8), RT + IgG (○, n = 11), or RT + 9H10 (•, n = 10). Points, mean for each treatment group; bars, ±SE. Tumor volume is shown up to day 39 only because afterwards too many animals died. *, P < 0.01, statistically significant difference (from day 20) when compared with IgG-treated control group (B). Percentage of surviving mice following treatment with control IgG (thin broken line, n = 11), 9H10 (thin line, n = 8), RT + IgG (bold broken line, n = 11), or RT + 9H10 (bold line, n = 10). Survival differences between treatment groups were analyzed using a Weibull model; *, P < 0.0005, statistically significant difference between RT + 9H10 and all the other groups.
- Fig. 2
Inhibition of lung metastases by RT to the primary tumor and CTLA-4 blockade requires CD8+ T cells. Treatment was started on day 13 after s.c. inoculation with the 4T1 mammary carcinoma in the flank. RT was delivered by a single dose of 12 Gy to the s.c. tumors. 9H10 and control hamster IgG were given i.p. 1, 4, and 7 days after RT. A, effect of treatment on lung metastases. Mice were sacrificed on day 35 and lung metastases counted. One animal in IgG, 9H10, and RT + IgG group died on days 32, 33, and 34, respectively, and lung metastases were counted at death. Symbol, single animal; horizontal lines, median number of metastases for each treatment group (n = 7 per group). The decrease in number of metastases after RT was statistically significant (P < 0.05) only in the presence of 9H10 according to Mann-Whitney test. B, depletion of CD8+ T cells abolishes the antimetastatic effect of RT + 9H10 treatment. Antibody-mediated CD4+ and CD8+ T-cell depletion was begun on day 10 and maintained up to the day of sacrifice as described in Materials and Methods. Mice were sacrificed on day 32 and lung metastases counted. Symbol, single animal; horizontal lines, median number of metastases for each treatment group. Each group comprised six mice, but two animals, one in control IgG and one in the group depleted of CD8+ T cells died at day 24 and were not included in the study. The difference in number of metastases between mice treated with RT + 9H10 and control IgG was statistically significant (P < 0.02) in the absence of T-cell depletion (None) and in the absence of CD4+ T cells (CD4), but not in the absence of CD8+ T cells (CD8) according to Mann-Whitney test.
- Fig. 3
Effects of two fractions of local RT in combination with CTLA-4 blockade on the primary tumor growth and survival of mice bearing the nonimmunogenic 4T1 carcinoma. Treatment was started on day 13 post-s.c. inoculation with the 4T1 mammary carcinoma in the flank. RT was delivered by two fractions of 12 Gy given at 48 hours interval to the s.c. tumors. Antibodies were given i.p. 1, 4, and 7 days after the second RT fraction. A-C, Primary tumor growth delay/regression by RT. Mice received RT + control hamster IgG (A), RT + anti-CTLA-4 mAb 9H10 (B), or control IgG only (C). Line, single mouse. Bold lines, primary tumors that showed complete temporary or permanent regression. Numbers, mice with complete tumor regression over the total number of mice treated. D, percentage of surviving mice following treatment with control IgG (thin broken line), RT + IgG (thin line), or RT + 9H10 (bold line). *, tumor cure. The survival difference between RT + 9H10 and the other groups was statistically significant (P < 0.001) according to analysis using a Weibull model. Representative of two similar experiments.
- Fig. 4
Tumor cure following RT and CTLA-4 blockade is associated with development of 4T1-specific cytolytic T cells. Spleen cells isolated from a mouse cured from the 4T1 tumor and restimulated in vitro as described in Materials and Methods were tested for the ability to kill 4T1 (⧫) and the A20 lymphoma (◊) cells at various effector to target ratios, as indicated. Representative of two experiments.
Volume 11, Issue 2
