Chronic graft-versus-host disease after allogeneic peripheral-blood stem-cell transplantation: a little methotrexate goes a long way

Instrumental variable meta-analysis of individual patient data: application to adjust for treatment non-compliance

Background

Intention-to-treat (ITT) is the standard data analysis method which includes all patients regardless of receiving treatment. Although the aim of ITT analysis is to prevent bias due to prognostic dissimilarity, it is also a counter-intuitive type of analysis as it counts patients who did not receive treatment, and may lead to "bias toward the null." As treated (AT) method analyzes patients according to the treatment actually received rather than intended, but is affected by the selection bias. Both ITT and AT analyses can produce biased estimates of treatment effect, so instrumental variable (IV) analysis has been proposed as a technique to control for bias when using AT data. Our objective is to correct for bias in non-experimental data from previously published individual patient data meta-analysis by applying IV methods

Methods

Center prescribing preference was used as an IV to assess the effects of methotrexate (MTX) in preventing debilitating complications of chronic graft-versus-host-disease (cGVHD) in patients who received peripheral blood stem cell (PBSCT) or bone marrow transplant (BMT) in nine randomized controlled trials (1107 patients). IV methods are applied using 2-stage logistic, 2-stage probit and generalized method of moments models.

Results

ITT analysis showed a statistically significant detrimental effect with the use of day 11 MTX, resulting in cGVHD odds ratio (OR) of 1.34 (95% CI 1.02-1.76). AT results showed no difference in the odds of cGVHD with the use of MTX [OR 1.31 (95%CI 0.99-1.73)]. IV analysis further corrected the results toward no difference in the odds of cGVHD between PBSCT vs. BMT, allowing for a possibility of beneficial effects of MTX in preventing cGVHD in PBSCT recipients (OR 1.14; 95%CI 0.83-1.56).

Conclusion

All instrumental variable models produce similar results. IV estimates correct for bias and do not exclude the possibility that MTX may be beneficial, contradicting the ITT analysis.

Allogeneic Intrabone Marrow-Bone Marrow Transplantation plus Donor Lymphocyte Infusion Suppresses Growth of Colon Cancer Cells Implanted in Skin and Liver of Rats

We have recently found that allogeneic intrabone marrow-bone marrow transplantation (IBM-BMT) + donor lymphocyte infusion (DLI) using CD4(+) cell-depleted spleen cells (CD4(-) cells) can prevent graft-versus-host disease (GvHD) but suppress tumor growth (Meth A: fibrosarcoma) in mice. In the present study, we show that allogeneic IBM-BMT + DLI using CD4(-) cells also has suppressive effects on the growth of colon cancer cells implanted not only in the skin but also in the liver of rats. First, we examined the effects of allogeneic IBM-BMT + DLI on the subcutaneously inoculated ACL-15 (rat colon cancer cell line). Lethally irradiated Fischer rats (F344 rats) were transplanted with T-cell-depleted bone marrow cells (BMCs) from Brown Norway (BN) rats. Simultaneously, DLI was performed using whole spleen cells (whole cells), CD4(+) cell-depleted spleen cells (CD4(-) cells) or CD8(+) cell-depleted spleen cells (CD8(-) cells) of BN rats. Although allogeneic IBM-BMT + DLI suppressed tumor growth, a considerable number of rats treated with allogeneic IBM-BMT + DLI using whole cells or CD8(-) cells died due to GvHD. In contrast, allogeneic IBM-BMT + DLI using CD4(-) cells also suppressed tumor growth, but there was no GvHD. Based on these findings, we next examined the effects of allogeneic IBM-BMT + DLI using CD4(-) cells on the cancer cells implanted in the liver. Allogeneic IBM-BMT + DLI using CD4(-) cells via the portal vein significantly prolonged the survival. These results suggest that allogeneic IBM-BMT + DLI using CD4(-) cells could become a new strategy for the treatment of solid tumors.

Comparative analysis of clinical outcomes after allogeneic bone marrow transplantation versus peripheral blood stem cell transplantation from a related donor in Japanese patients

A reduced incidence of graft versus host disease (GvHD) has been documented among Japanese allogeneic bone marrow transplantation (BMT) patients, as the Japanese are genetically more homogeneous than western populations. To clarify whether this ethnic difference affects the results of allogeneic peripheral blood stem cell transplantation (PBSCT), we conducted a nationwide survey to compare clinical outcomes of allogeneic PBSCT (n = 214) and BMT (n = 295) from a human leucocyte antigen-identical-related donor in Japanese patients. The cumulative incidence of grades II-IV acute GvHD was 37.4% for PBSCT and 32.0% for BMT. The cumulative incidence of extensive chronic GvHD at 1 year was significantly higher after PBSCT than BMT (42% vs. 27%; P < 0.01). The organ involvement patterns of GvHD were different between the two groups. By multivariate analyses, the incidence of chronic GvHD was significantly increased in PBSCT, whereas the stem cell source did not affect the incidence of acute GvHD, transplant-related mortality, relapse or survival. We concluded that Japanese PBSCT patients have an increased risk of chronic GvHD compared with BMT patients, but the incidence of acute GvHD was still lower than in western populations. Thus, the choice of haematopoietic stem cell source should be considered based on data for individual ethnic populations.