FCGRT and telomere syndrome: Accordingly, SPEDOX-6 recycling efficiency in xenograft tumor cells would be inversely correlated with the FcRn expression level, which is consistent with the antitumor efficacy–FcRn relationship in Figure 6D. The relationship will be tested in SPEDOX-6’s current clinical trials on STS, where the archival tumor tissues of STS patients will be analyzed for FcRn expression level in order to correlate to SPEDOX-6 treatment efficacy, as requested by the FDA.