Availability of HLA-allele-matched unrelated donors and registry size: Estimation from haplotype frequency in the Italian population

In Italy, an HLA-matched unrelated donor is currently the primary donor when a HLA matched sibling is not found for allogeneic haematopoietic stem cell transplantation (HSCT). Better outcomes for transplantation require optimal matching between donor and recipient at least at the HLA-A, -B, -C, and -DRB1 loci; therefore, the availability of HLA-matched unrelated donors is important. The enormous HLA polymorphism has always necessitated registries with a large number of individuals in order to be able to provide well-matched donors to a substantial percentage of patients. In order to increase the efficiency of the Italian Bone Marrow Donor Registry (IBMDR) in providing Italian patients with a suitable donor, the probability of finding an HLA-A, -B, -C, and -DRB1 allele-matched (8/8) or a single mismatch unrelated donor (7/8) was estimated in this study according to IBMDR size. Using a biostatistical approach based on HLA haplotype frequencies of more than 100,000 Italian donors enrolled in the IBMDR and HLA-typed at high-resolution level, the probability of finding an 8/8 HLA-matched donor was 23.8%; 33.4%; and 41.4% in simulated registry sizes of 200,000; 500,000; and 1,000,000 donors; respectively. More than 2 million recruited donors are needed to increase the likelihood of identifying an HLA 8/8 matched donor for 50% of Italian patients. If one single mismatch at HLA I class loci was accepted, the probability of finding a 7/8 HLA-matched donor was 62.8%; 73.7%; and 80.3% in 200,000 donors; 500,000; and 1,000,000 donors; respectively. Using the regional haplotype frequencies of IBMDR donors, the probability of recruiting a donor with a new HLA phenotype, in the different Italian regions, was also calculated. Our findings are highly relevant in estimating the optimal size of the national registry, in planning a cost-effective strategy for donor recruitment in Italy, and determining the regional priority setting of recruitment activity in order to increase the phenotypic variability of IBMDR as well as its efficiency.

Treating ApoE−/− mice with Toll-like receptor 7 ligand lead to expansion of marginal zone B cells, reduced plasma cholesterol and decreased atherosclerosis

Background

The interplay between innate and adaptive immunity is involved in the cause of the life-threatening events in atherosclerosis, such as myocardial infarction and stroke. We have previously shown that higher levels of Toll-like receptor 7 (TLR7) expression in human atherosclerotic lesions are correlated to better patient outcome, emphasizing the role of the innate pattern recognizing receptors in the pathogenesis of atherosclerosis.

Purpose

Firstly, to investigate if activation of the innate immune receptor TLR7 in vivo in experimental atherosclerosis is a potential way to reduce disease and secondly to identify pathways upon TLR7 ligation treatment.

Methods

Apolipoprotein E (ApoE−/−) deficient mice with established disease were injected intraperitoneal with a TLR7 ligand. Local effects were evaluated by characterization of atherosclerotic lesions. Systemic effects of the treatment were investigated by immune composition analysis in the spleen and by plasma measurements

Results

In vivo treatment of ApoE−/−mice with TLR7 ligand arrested atherosclerotic lesion development in the aortic root. Moreover, in the lesions of the treated mice we detected decrease in necrotic area and decrease in accumulation of apoptotic cells. In the spleen we detected an expansion of marginal zone B cells accompanied with an increase in IgM antibodies against oxidized low-density lipoprotein (oxLDL). The treated mice had reduced plasma cholesterol levels.

Conclusions

In vivo administration of TLR7 ligand ameliorated the atherosclerotic burden in old ApoE−/− mice. Our findings indicate that TLR7 ligation is involved in control of inflammatory responses in atherosclerosis, suggesting that TLR7 is a potential therapeutic target. Further analysis is needed in order to elucidate the underlying mechanisms by which TLR7 exerts its protective role.

Funding Acknowledgement

Type of funding source: Private grant(s) and/or Sponsorship. Main funding source(s): Swedish Heart-Lung Foundation

Pembrolizumab and nab-paclitaxel as salvage therapy for platinum-treated, locally advanced or metastatic urothelial carcinoma: interim results of the open-label, single-arm, phase II PEANUT study

BACKGROUND

Pembrolizumab is a new standard of care for patients with platinum-treated, metastatic urothelial carcinoma (UC). Nab-paclitaxel is active in advanced UC. In the PEANUT study (NCT03464734) we investigated their combination in advanced UC.

PATIENTS AND METHODS

PEANUT was an open-label, single-arm, phase II trial that included patients who had failed one or two chemotherapy regimens, including platinum chemotherapy. Biomarker analyses focused on programmed cell-death ligand-1 combined positive score (CPS) and comprehensive genomic profiling on tumor samples and circulating tumor DNA. Patients received 200 mg pembrolizumab on day 1 (D1), and 125 mg/m² nab-paclitaxel on D1 and D8, every 3 weeks, until disease progression or unacceptable toxicity. The primary end point was progression-free survival (PFS) according to RECIST (v1.1). The assumption was to detect an improvement in the median PFS from ≤3.0 months (H0) to ≥5.0 months (H1).

RESULTS

Between January 2019 and January 2020, the PEANUT study enrolled 70 patients: 24% had failed two prior systemic therapies; 31% had an Eastern Cooperative Oncology Group (ECOG) performance status of 1; and 28.6% had liver metastases. After a median follow-up of 9.8 months, 40 patients have relapsed (57.1%). The median PFS was 5.9 months [95% confidence interval (CI) 3.1-11.5]. The confirmed objective response rate (ORR) was 38.6% (95% CI 27-51) with 17 partial responses and 10 complete responses (14.3%). The median duration of response was not reached. Five patients (7.1%) had ongoing responses lasting >12 months. The most common any-grade treatment-related adverse events included alopecia (71.4%), neutropenia (32.9%), and peripheral neuropathy (34.3%). Neither tumor mutational burden nor CPS was significantly associated with PFS at univariable analyses. The single-arm design of the trial was the major limitation.

CONCLUSIONS

Pembrolizumab combined with nab-paclitaxel, as second- and third-line chemoimmunotherapy for metastatic UC, showed a favorable safety profile, durable PFS, and a clinically meaningful ORR in these preliminary analyses. This combination warrants additional randomized studies in earlier disease stages. CLINICALTRIALS.

GOV NUMBER

ClinicalTrials.govNCT03464734; https://clinicaltrials.gov/ct2/show/NCT03464734.