BackgroundThe calreticulin (CALR) exon 9 mutations that are identified in 20% of patients with Philadelphia chromosome negative chronic myeloproliferative neoplasms (MPN) generate immunogenic antigens. Thus, therapeutic cancer vaccination against mutant CALR could be a new treatment modality in CALR-mutant MPN.MethodsThe safety and efficacy of vaccination with the peptide CALRLong36 derived from the CALR exon 9 mutations was tested in a phase I clinical vaccination trial with montanide as adjuvant. Ten patients with CALRmut MPN were included in the trial and received 15 vaccines over the course of one year. The primary end point was evaluation of safety and toxicity of the vaccine. Secondary endpoint was assessment of the immune response to the vaccination epitope (www.clinicaltrials.gov identifier NCT03566446).ResultsPatients had a median age of 59.5 years and a median disease duration of 6.5 years. All patients received the intended 15 vaccines, and the vaccines were deemed safe and tolerable as only two grade three AE were detected, and none of these were considered to be related to the vaccine. A decline in platelet counts relative to the platelets counts at baseline was detected during the first 100 days, however this did not translate into neither a clinical nor a molecular response in any of the patients. Immunomonitoring revealed that four of 10 patients had an in vitro interferon (IFN)-γ ELISPOT response to the CALRLong36 peptide at baseline, and four additional patients displayed a response in ELISPOT upon receiving three or more vaccines. The amplitude of the immune response increased during the entire vaccination schedule for patients with essential thrombocythemia. In contrast, the immune response in patients with primary myelofibrosis did not increase after three vaccines.ConclusionTherapeutic cancer vaccination with peptide vaccines derived from mutant CALR with montanide as an adjuvant, is safe and tolerable. The vaccines did not induce any clinical responses. However, the majority of patients displayed a marked T-cell response to the vaccine upon completion of the trial. This suggests that vaccines directed against mutant CALR may be used with other cancer therapeutic modalities to enhance the anti-tumor immune response.

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Objective In patients with large B‐cell lymphoma (LBCL) according to WHO, the prognostic significance of MYC translocation is still not sufficiently clarified. We therefore aimed to investigate whether prognostication could be improved in patients with MYC translocation positive LBCL by additional stratification according to MYC and BCL2 protein expression levels or MYC translocation partner gene as well as concurrent BCL2 and/or BCL6 translocation (DH). Methods From an unselected consecutive cohort of >600 patients with LBCL investigated with fluorescent in situ hybridization (FISH), 64 patients were diagnosed with MYC translocation positive LBCL and included in the study. They were further investigated for supplemental translocations with FISH and MYC and BCL2 protein expression with immunohistochemistry (IHC). Results MYC expression >75% was associated with both reduced progression‐free survival (PFS) and overall survival (OS) (PFS: HR 6.8 (95% CI 1.5‐31), P = 0.004. OS: HR 4.3 (95% CI 0.9‐21), P = 0.05). Immunoglobulin (IG) MYC translocation partner gene was related to high MYC protein expression (P = 0.047) but was not prognostic for PFS (P = 0.8) or OS (P = 0.6). DH did not confer a worse outcome compared to MYC single hit (SH). These findings were confirmed in a comparable, independent validation cohort of 28 patients with MYC translocation positive LBCL. All patients included in the survival analyses were treated with R‐CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) or R‐CHOEP (R‐CHOP + etoposide). Conclusion These findings suggest that in patients with LBCL stratification by MYC protein expression level significantly improves the prognostic impact associated with MYC translocation.