No abstract

SARS-CoV-2 infection and vaccination have raised concerns in paroxysmal nocturnal hemoglobinuria (PNH). In fact, PNH patients carry an increased infectious risk secondary to complement inhibition treatment or associated bone marrow failure (BMF), and may therefore benefit from preventive strategies such as vaccinations. On the contrary, vaccines can be numbered among inflammatory complement amplifiers (e.g., infections, traumas, surgery), potentially triggering a disease exacerbation. In PNH patients on complement inhibitors, this phenomenon has been defined pharmacodynamic breakthrough hemolysis (BTH). Based on isolated reports of BTH following SARS-CoV-2 vaccines, we conducted a survey among 5 Italian reference centers to evaluate complications and BTH occurrence in PNH patients who completed the SARS-CoV-2 vaccination schedule from January, 2 2021 until the time of writing. Adverse events, hematologic and hemolytic parameters were recorded within 7-10 days before and after each dose of vaccine. A total of 67 patients (females/males 43/24, median age 47.6 years, range 21-90.5) were eligible for the analysis. According to the International PNH Interest Group classification, 45 patients suffered from hemolytic PNH, 20 from PNH in the context of BMF syndromes (aplastic anemia or myelodysplastic syndrome), and 2 from subclinical PNH. Fifty-five subjects (82%) were on regular complement inhibition therapy, i.e., eculizumab (N=35), ravulizumab (N=13), subcutaneous anti-C5 (N=3), anti-factor B (N=2) and ravulizumab + anti-factor D combination (N=2). Vaccines (Comirnaty/Pfizer-BioNTech N=53, mRNA-1273/Moderna N=12, and ChAdOx1 nCov-19/AstraZeneca N=2) were complessively well-tolerated, with 3 non-hematologic adverse events after the first dose (2 fever and 1 exercise-induced tachycardia, grade 1 according to CTCAE v5.0) and 2 after the second one (fever, accompanied by vomit in one patient, grade 1). During the observation period, 3 BTH and 1 hemolytic exacerbation were recorded (5.9% of patients), as detailed in Table 1. The most severe episode occurred in a young woman (Patient 3) on subcutaneous ravulizumab who experienced a hemoglobin (Hb) drop >2 g/dL, marked clinical signs of intravascular hemolysis and lactate dehydrogenase (LDH) increase >1.5 x upper limit of normal (ULN) from baseline, which is considered a clinical BTH according to the criteria proposed by the Severe Aplastic Anemia Working Party of the European group for Bone Marrow Transplantation. The patient required hospitalization for additional treatment with recombinant erythropoietin and anti-thombotic/bacterial prophylaxis. The second more severe BTH was registered in a male patient (Patient 1) on oral anti-factor B who experienced a Hb drop >2 g/dL without an overt hemolytic flare, and required hospitalization for intravenous antibiotic therapy (concomitant urinary tract infection). The remaining two patients experienced a subclinical BTH (Patient 2) and a hemolytic flare (Patient 4, not on complement inhibition). On the whole, a median delta variation from usual values of Hb and LDH of -25% (range -26+3%) and +80% (+18+105%) were observed, respectively. Of note, 3 episodes occurred after the second dose of vaccine, generally within 24-48 hours. Anti-complement drugs were not modified/discontinued in any of the 3 patients on regular treatment. Patients not experiencing BTH (94.1%) showed stable hematologic parameters after the first dose (Hb/LDH median delta variations from baseline -1%/+1%, range -14+12%/-32+40%) and the second dose of vaccine (Hb/LDH median delta variations from baseline +1%/0%, range -18+47%/-76+41%). Of note, 4 patients with a previous SARS-CoV-2 infection completed the vaccination without any complication/PNH exacerbation. In conclusion, this survey shows that BTH/hemolytic flares following SARS-CoV-2 vaccines are observed in about 6% of PNH patients, may be clinically relevant but manageable, and should not discourage vaccination. BTH has been registered mostly few days after the second dose of vaccine, suggesting a "booster" effect favoring a higher inflammatory response. Watchful clinical and laboratory monitoring is advised, in order to promptly recognize severe hemolytic flares in both treated and naïve patients. Figure 1 Figure 1. Disclosures Fattizzo: Novartis: Speakers Bureau; Kira: Speakers Bureau; Alexion: Speakers Bureau; Annexon: Consultancy; Momenta: Honoraria, Speakers Bureau; Apellis: Speakers Bureau; Amgen: Honoraria, Speakers Bureau. Bianchi: Agios pharmaceutics: Consultancy, Membership on an entity's Board of Directors or advisory committees. Sica: Jazz Pharma: Consultancy; Alexion: Consultancy. Barcellini: Novartis: Other: Invited speaker, Research Funding; Agios: Membership on an entity's Board of Directors or advisory committees; Alexion Pharmaceuticals, Inc: Membership on an entity's Board of Directors or advisory committees, Other: Invited speaker, Research Funding; Bioverativ: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees.

Despite substantial improvements in breast cancer (BC) treatment there is still an urgent need to find alternative treatment options to improve the outcomes for patients with advanced-stage disease. Photodynamic therapy (PDT) is gaining a lot of attention as a BC therapeutic option because of its selectivity and low off-target effects. However, the hydrophobicity of photosensitizers (PSs) impairs their solubility and limits the circulation in the bloodstream, thus representing a major challenge. The use of polymeric nanoparticles (NPs) to encapsulate the PS may represent a valuable strategy to overcome these issues. Herein, we developed a novel biomimetic PDT nanoplatform (NPs) based on a polymeric core of poly(lactic-co-glycolic)acid (PLGA) loaded with the PS meso-tetraphenylchlorin disulfonate (TPCS2a). TPCS2a@NPs of 98.89 ± 18.56 nm with an encapsulation efficiency percentage (EE%) of 81.9 ± 7.92% were obtained and coated with mesenchymal stem cells-derived plasma membranes (mMSCs) (mMSC-TPCS2a@NPs, size of 139.31 ± 12.94 nm). The mMSC coating armed NPs with biomimetic features to impart long circulation times and tumor-homing capabilities. In vitro, biomimetic mMSC-TPCS2a@NPs showed a decrease in macrophage uptake of 54% to 70%, depending on the conditions applied, as compared to uncoated TPCS2a@NPs. Both NP formulations efficiently accumulated in MCF7 and MDA-MB-231 BC cells, while the uptake was significantly lower in normal breast epithelial MCF10A cells with respect to tumor cells. Moreover, encapsulation of TPCS2a in mMSC-TPCS2a@NPs effectively prevents its aggregation, ensuring efficient singlet oxygen (1O2) production after red light irradiation, which resulted in a considerable in vitro anticancer effect in both BC cell monolayers (IC50 < 0.15 µM) and three-dimensional spheroids.