Alexa Siddon, MD
Professor of Laboratory MedicineCards
About
Research
Publications
2025
Hypomethylating Agent and Venetoclax Combination Is a Safe and Effective Alternative to Intensive Chemotherapy in Older (≥ 70 Years) Patients With Newly Diagnosed Favorable Risk Acute Myeloid Leukemia
Ball S, Jain A, Al Ali N, Aguirre L, Bewersdorf J, Kent A, Rose A, Hayden A, Siddon A, Lykon J, Madarang E, Swoboda D, Padron E, Sweet K, Sallman D, Lancet J, Carraway H, Watts J, Zeidan A, Pollyea D, Komrokji R. Hypomethylating Agent and Venetoclax Combination Is a Safe and Effective Alternative to Intensive Chemotherapy in Older (≥ 70 Years) Patients With Newly Diagnosed Favorable Risk Acute Myeloid Leukemia. American Journal Of Hematology 2025, 100: 1920-1923. PMID: 40772639, DOI: 10.1002/ajh.70031.Peer-Reviewed Original Research382 | GENE COPY NUMBER ALTERATIONS IDENTIFY SUBSET OF SEZARY SYNDROME PATIENTS WITH WORSE SURVIVAL OUTCOMES
Kiwan A, Foss F, Girardi M, Xu M, Siddon A, Sethi T. 382 | GENE COPY NUMBER ALTERATIONS IDENTIFY SUBSET OF SEZARY SYNDROME PATIENTS WITH WORSE SURVIVAL OUTCOMES. Hematological Oncology 2025, 43 DOI: 10.1002/hon.70094_382.Peer-Reviewed Original ResearchHeterogeneity in outcomes of TP53‐mutated myeloproliferative neoplasms based on disease phenotype and mutational status
Badar T, Foran J, Bewersdorf J, Wang Y, Coltoff A, Kettani M, Shah K, Oliva F, Lin C, Jamy O, Diebold K, Shallis R, Siddon A, Katkov D, Schoen A, Khan I, Foucar C, Atallah E, Goldberg A, Patel A. Heterogeneity in outcomes of TP53‐mutated myeloproliferative neoplasms based on disease phenotype and mutational status. British Journal Of Haematology 2025, 207: 683-686. PMID: 40400334, DOI: 10.1111/bjh.20187.Peer-Reviewed Original ResearchAssessing AML-based risk criteria in patients with accelerated/blast-phase MPN treated with less-intensive therapy
Shaw R, Yoon J, Johnston H, Davidson M, Siddon A, Shallis R, Chen E, Burkart M, Oh T, Iyer S, Madarang E, Muthiah C, Kassner J, Rampal R, Murthy S, Bradley T, Abaza Y, Garcia J, Gupta V, Pettit K, Odenike O, Patel A. Assessing AML-based risk criteria in patients with accelerated/blast-phase MPN treated with less-intensive therapy. Blood Advances 2025, 9: 2453-2457. PMID: 39969200, PMCID: PMC12144506, DOI: 10.1182/bloodadvances.2024015712.Peer-Reviewed Original ResearchImpact of memory T cells on SARS-CoV-2 vaccine response in hematopoietic stem cell transplant
VanOudenhove J, Liu Y, Nelakanti R, Kim D, Busarello E, Ovalle N, Qi Z, Mamillapalli P, Siddon A, Bai Z, Axtmayer A, Corso C, Kothari S, Foss F, Isufi I, Tebaldi T, Gowda L, Fan R, Seropian S, Halene S. Impact of memory T cells on SARS-CoV-2 vaccine response in hematopoietic stem cell transplant. PLOS ONE 2025, 20: e0320744. PMID: 40294012, PMCID: PMC12036906, DOI: 10.1371/journal.pone.0320744.Peer-Reviewed Original ResearchConceptsHematopoietic stem cell transplantationMemory T cellsStem cell transplantationCell transplantationT cellsSARS-CoV-2Hematopoietic stem cell transplant recipientsAntigen-specific T-cell activationSARS-CoV-2 mRNA vaccinesSARS-CoV-2 vaccine responsesSevere diseaseAnti-spike IgGT cell activationAdaptive immune responsesRobust antibody responsesPost-vaccination responseSARS-CoV-2 infectionMRNA vaccine seriesSingle-cell RNAMyeloablative chemotherapyCellular responsesImmune profileVaccine responseCOVID-19 infectionMRNA vaccinesInvestigation of NPM1 mutation frequency in cutaneous blastic plasmacytoid dendritic cell neoplasms
Hamdan H, Siddon A, Ramia de Cap M, Germans S, Cantu M, Fuda F, Vandergriff T, Aggarwal N, Weinberg O. Investigation of NPM1 mutation frequency in cutaneous blastic plasmacytoid dendritic cell neoplasms. Human Pathology 2025, 158: 105766. PMID: 40216030, DOI: 10.1016/j.humpath.2025.105766.Peer-Reviewed Original ResearchConceptsBlastic plasmacytoid dendritic cell neoplasmBPDCN patientsBPDCN casesCutaneous blastic plasmacytoid dendritic cell neoplasmAcute myeloid leukemiaPlasmacytoid dendritic cell neoplasmDendritic cell neoplasmNPM1 mutationsMyeloid sarcomaCell neoplasmsSarcoma patientsImmunohistochemical stainingAbsence of NPM1 mutationsFrequency of NPM1 mutationsBone marrow of patientsLow white blood cell countCutaneous myeloid sarcomaWhite blood cell countMarrow of patientsTime of diagnosisHigher hemoglobin levelsBlood cell countPercentage of involvementSRSF2 mutationsComplex karyotypeTP53‐Mutated Acute Myeloid Leukemia and Blast Phase Myeloproliferative Neoplasm: Distinct Mutation Leads to Poorer Prognosis
Chen D, Cantu M, Siddon A, Weinberg O. TP53‐Mutated Acute Myeloid Leukemia and Blast Phase Myeloproliferative Neoplasm: Distinct Mutation Leads to Poorer Prognosis. European Journal Of Haematology 2025, 115: 57-63. PMID: 40152319, PMCID: PMC12134709, DOI: 10.1111/ejh.14421.Peer-Reviewed Original ResearchConceptsAcute myeloid leukemiaTP53-mutated acute myeloid leukemiaBlast phase myeloproliferative neoplasmsTP53 mutationsClinical outcomesMPN-BPMyeloproliferative neoplasmsMyeloid leukemiaAssociated with prognostic significanceMissense mutationsLow-risk groupSplice site variantOverall survivalAssociated with relatively better prognosisMyeloid neoplasmsPrognostic significanceBetter prognosisTP53 mutantsTherapeutic responseRisk stratificationRetrospective analysisExon 5TP53Exon 6Poorer PrognosisResponse and outcomes of patients with IDH1/2- mutated accelerated/blast-phase myeloproliferative neoplasms
Goldberg L, Yoon J, Johnston H, Davidson M, Siddon A, Shallis R, Chen E, Burkart M, Oh T, Iyer S, Madarang E, Muthiah C, Kassner J, Rampal R, Murthy S, Bradley T, Abaza Y, Garcia J, Gupta V, Pettit K, Odenike O, Cursio J, Patel A. Response and outcomes of patients with IDH1/2- mutated accelerated/blast-phase myeloproliferative neoplasms. Blood Neoplasia 2025, 2: 100089. PMID: 40949768, PMCID: PMC12423677, DOI: 10.1016/j.bneo.2025.100089.Peer-Reviewed Original ResearchChimerism testing in myeloid malignancies: techniques, considerations, and connections to post-transplant outcomes
Puzo C, Siddon A. Chimerism testing in myeloid malignancies: techniques, considerations, and connections to post-transplant outcomes. Pathology 2025, 57: 267-275. PMID: 39934013, DOI: 10.1016/j.pathol.2024.12.632.Peer-Reviewed Original ResearchLineage specific chimerismChimerism testingMyeloid malignanciesCell burdenHematopoietic cellsPost allogeneic stem cell transplantationHost hematopoietic cellsMalignant cell burdenLeukemic cell burdenStem cell transplantationRisk of relapseRecipient hematopoietic cellsPost-transplant outcomesCell transplantationRelapse detectionRecipient chimerismTherapy decisionsRelapsePercentage of donorsChimerismHigh riskConcurrent useChimerism percentageEarly identificationMalignancyDefining a lineage-specific chimerism threshold for the use of donor lymphocyte infusions in treating myeloid malignancies
Puzo C, Seropian S, Rinder H, Tormey C, Siddon A. Defining a lineage-specific chimerism threshold for the use of donor lymphocyte infusions in treating myeloid malignancies. Bone Marrow Transplantation 2025, 60: 535-537. PMID: 39806028, DOI: 10.1038/s41409-025-02510-8.Peer-Reviewed Original Research
Academic Achievements & Community Involvement
Clinical Care
Overview
Alexa Siddon, MD, is a pathologist who specializes in diagnosing diseases of the blood, such as leukemia and disorders, including bone marrow failure. Her interest in medicine began at a young age, when she accompanied her mother to the workplace—a clinical laboratory. In college, Dr. Siddon completed emergency medical technician (EMT) training and, later, decided to attend medical school.
“I chose pathology because I enjoy putting together the entire story of a patient to make a diagnosis,” says Dr. Siddon, who directs the hemopathology lab at the Veteran Affairs Connecticut Healthcare System. When examining patient samples, Dr. Siddon relies on an arsenal of sophisticated tools to make an accurate diagnosis. “For example, we might look at a bone marrow sample under a microscope, and we would also do genetic sequencing to see if we can discover genetic mutations that might make the patient eligible for a clinical trial.”
“My main focus is patient care,” Dr. Siddon says. “The more information I can give our colleagues, including hematology oncologists, the better care they can provide.”
At Yale School of Medicine, Dr. Siddon is an assistant professor of laboratory medicine.
Clinical Specialties
Pathology; Hematology & Oncology; Hematopathology; Pediatric Hematology & Oncology; Genetics
Fact Sheets
Cytogenic Studies for Leukemia Diagnosis
Learn More on Yale MedicineDiagnosing Leukemia
Learn More on Yale Medicine
Board Certifications
Hematology (Pathology)
- Certification Organization
- AB of Pathology
- Original Certification Date
- 2013
Anatomic & Clinical Pathology
- Certification Organization
- AB of Pathology
- Original Certification Date
- 2012
News
News
- June 12, 2025
Pathology, Laboratory Medicine Residents, Fellows Feted at Graduation Ceremony
- March 27, 2025
Yale Pathologists Share Insight, Latest Research at USCAP 2025
- October 21, 2024Source: MedTech Dive
5 steps to navigate the FDA's new lab developed test rule
- September 12, 2024
Alexa Siddon Receives ASCP Distinguished Educator Award
Get In Touch
Contacts
Academic Office Number
Mailing Address
Laboratory Medicine
330 Cedar Street, PO Box 208035
New Haven, CT 06520-8035
United States
Locations
Department of Laboratory Medicine
Academic Office
55 Park Street, Rm 435B
New Haven, CT 06511
Clinical Inquiry
203.688.4977
Events
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