RUX prophylaxis or therapy extends survival of CByB6F1 mice with immune-mediated BMF. Two independent experiments were performed to assess RUX efficacy extending animal survival in female and male CByB6F1 mice, in which data were combined from both experiments (A-C). (A) Eight- to 9-week-old female and male CByB6F1 mice preirradiated with 5 Gy TBI plus infusion of 5 × 10⁶ LN cells per mouse from B6 donors of the same gender to induce BMF. Mice were fed with Con-chow (Lab Diet 5002, BMF, n = 10+10) or with Rux-chow (2 g/kg ruxolitinib in Lab Diet 5002) starting at day −2 (BMF+RUXD−2, n = 10+10) or day 2 (BMF+RXD+2, n = 10+10) of LN cell infusion. Half of the mice fed with Rux-chow were switched to Con-chow at days 28 and 42, respectively, and mice were maintained with Con-chow for the remaining 28 and 14 days until animals were bled and euthanized at day 56. (B) Animals were weighed and bled biweekly to monitor body weight (BW) change and to measure blood NEUs, RBCs, and platelets PLTs. (C) Animal survival at day 56 following BMF induction, in which all mice in the BMF-RUXD−2 (n = 20) and BMF+RUXD+2 (n = 20) groups were alive at day 56, whereas mice in the BMF groups (n = 20) were found dead or moribund and requiring immediate euthanasia before day 20. (D) Delayed treatment of BMF mice with RUX. A third study was conducted to induce BMF in 9- to 15-week-old female CByB6F1 mice fed with Con-chow (Lab Diet 5002, BMF, n = 5) or Rux-chow (2 g/kg ruxolitinib in Lab Diet 5002) starting at day 4 (BMF+RUXD+4, n = 10), or day 6 (BMF+RXD+6, n = 10) after LN cell infusion, respectively. All mice fed with Rux-chow were switched to Con-chow at days 28 until animals were bled and euthanized at day 70. (E) BW and NEUs, RBCs, and PLTs of BM failure mice with delayed treatment. (F) All mice in the BMF+RUXD+4 and BMF+RUXD+6 groups were alive at day 70 following BMF induction, whereas all BMF mice were found dead at various time points. ∗∗∗∗P < .0001.