Mark Joseph Fesler, MD
NPI 1235204066ActiveIndividual· Internal Medicine, Hematology & Oncology· Saint Louis, MO
Internal Medicine, Hematology & Oncology (MD) in Saint Louis, Missouri, trained at Saint Louis University School of Medicine (class of 2003). Their prescriptions cost Medicare Part D more than their services did: $12,421,275 for 2,654 claims, against $194,833 paid for services in 2024. Incyte Corporation was the largest of 17 companies reporting payments in 2025, $195,858 in all, mostly speaking and faculty fees.
Overview
| NPI | 1235204066 |
|---|---|
| Status | Active |
| Entity type | Individual |
| Credential | MD |
| Sole proprietor | No |
| NPI issued | Nov 21, 2006 |
| Last updated in NPPES | Mar 29, 2021 |
| Certified by provider | Mar 29, 2021 |
Specialties and licenses
| Taxonomy | Code | License | State |
|---|---|---|---|
| Internal Medicine, Hematology & Oncology Primary | 207RH0003X | 2008029015 | MO |
| Internal Medicine | 207R00000X | 43133 | CO |
Exclusion screening
| List | Result | Details |
|---|---|---|
| HHS-OIG LEIE · Oct 9, 2026 | No match | Checked by NPI and by name + state |
| North Carolina Medicaid · Nov 10, 2026 | No match | — |
| New York OMIG · Nov 10, 2026 | No match | — |
| Ohio Medicaid · Nov 10, 2026 | No match | — |
| Pennsylvania Medicheck · Nov 10, 2026 | No match | — |
| Washington HCA · Nov 10, 2026 | No match | — |
Official OIG search · How matching works ·Bulk check a roster
Medicare
| Enrollment (PECOS) | Enrolled Practitioner - Hematology/Oncology (MO) |
|---|---|
| Accepts assignment | Yes (participating) |
Medicare services in 2024
| Medicare patients | 258 |
|---|---|
| Services billed | 2,082 across 16 procedure codes |
| Paid by Medicare | $194,833 |
Part D prescriptions in 2024
| Prescriptions (claims) | 2,654 · 3,665 30-day fills |
|---|---|
| Patients | 229 |
| Total drug cost | $12,421,275 |
| Generic share | 70% of claims |
Education and affiliations
| Medical school | Saint Louis University School of Medicine |
|---|---|
| Graduation year | 2003 |
| Medicare specialty | Hematology/Oncology |
| Secondary specialties | Hematopoietic Cell Transplantation And Cellular Therapy |
| Telehealth | Offers telehealth |
Medical group
- Van Amburg and Busiek Mds LLCChesterfield, MO · 9 clinicians
Hospital affiliation
- St Lukes HospitalChesterfield, MO
Industry payments (Open Payments)
- 2025$195,858 · 114 payments from 17 companies
- 2024$192,797 · 134 payments from 19 companies
Top paying companies in 2025
| Company | Amount | Payments |
|---|---|---|
| Incyte Corporation | $47,295 | 29 |
| Abbvie Inc. | $42,988 | 28 |
| Adc Therapeutics America, Inc. | $28,673 | 13 |
| Beone Medicines USA, Inc. | $20,132 | 10 |
| Genzyme Corporation | $15,174 | 5 |
What the 2025 payments were for
- Compensation for services other than consulting, including serving as faculty or as a speaker at a venue other than a continuing education program$135,146 · 45 payments
- Honoraria$24,820 · 5 payments
- Consulting Fee$19,694 · 10 payments
- Travel and Lodging$13,336 · 14 payments
- Food and Beverage$2,862 · 40 payments
Receiving payments does not imply wrongdoing. What Open Payments covers ·original records
Other Internal Medicine, Hematology & Oncology providers in Saint Louis
- 1629304423
- 1437489168
- 1356316103
- 1811046949
- 1154637395
- 1932206935
- 1477562965
- 1215063110
- 1649498932
- 1871093690
- 1932156726
- 1083147359
All Internal Medicine, Hematology & Oncology providers in Missouri →