Treating the Source: Standard of Care Therapy

The treatment strategy for Monoclonal Immunoglobulin Deposition Disease (MIDD) generally follows a single, vital principle: treat the bone marrow to save the kidney.

Because the abnormal proteins damaging your kidneys are produced by a clone of cells in your bone marrow, clone-directed treatment is generally considered to suppress the source ^[1]. Even if your bone marrow clone is small, it can cause progressive kidney injury, so therapy selected by a hematology team is required ^[2].

First-Line Chemotherapy and Targeted Therapy

The choice of therapy depends on several factors, including whether the clone is plasma-cell or B-cell, whether you have LCDD or HCDD, your kidney function, comorbidities, and prior therapy.

• Bortezomib-Based Regimens: For plasma-cell clones, bortezomib (a proteasome inhibitor) is commonly used ^[1]. It works by preventing cells from breaking down old proteins, causing the abnormal plasma cells to die. It is often combined with dexamethasone (a steroid) ^[3].
• CyBorD: Some doctors add cyclophosphamide to the mix, a regimen known as CyBorD (Cyclophosphamide, Bortezomib, and Dexamethasone) ^[4].
• Targeting the Clone: The goal is to achieve a deep hematologic response, significantly reducing the amount of abnormal proteins ^[5]. Achieving a deep response is strongly associated with whether your kidneys will stabilize or improve ^[6][7]. B-cell clones may require a completely different approach.

Autologous Stem Cell Transplant (ASCT)

For selected patients, an autologous stem cell transplant may be an option ^[3].

1. Induction: You first receive therapy to lower the protein levels.
2. Collection: Your own stem cells are collected and frozen.
3. High-Dose Melphalan: You receive conditioning therapy (a high dose of melphalan) designed to suppress the remaining abnormal cells in the bone marrow.
4. Rescue: Your frozen stem cells are returned to your body to restore marrow function.

Eligibility is individualized using performance status, cardiac and pulmonary function, kidney status, comorbidities, and center experience; age alone is not the deciding factor ^[8]. Selected dialysis patients may be considered, but this requires specialist-center assessment and carries substantial risks ^[9].

Understanding Treatment Risks

All effective treatments carry the risk of side effects, which your team will monitor closely. Ensure you have clear instructions on when to call your team:

• Peripheral Neuropathy: Bortezomib can damage nerves, leading to numbness, tingling, or “burning” pain. A 19% neuropathy rate has been reported in certain MIDD cohorts, but the rate depends heavily on the study, the bortezomib route, and the schedule ^[1].
• Infection Risk: These treatments suppress your immune system. Antiviral prophylaxis is commonly considered with bortezomib, while antibacterial or Pneumocystis prophylaxis is regimen- and risk-dependent rather than routine for every patient ^[10]. Follow urgent instructions for any fever.
• Fluid and Steroid Side Effects: Dexamethasone can cause fluid retention, mood changes, and high blood sugar ^[11].

Supportive Kidney Care and Recovery

While the hematologist manages the clone, individualized kidney-protective care is critical. This includes blood-pressure and proteinuria control, edema management (using diuretics and sodium restriction), avoidance of kidney-toxic medicines, and dialysis planning when needed.

It is important to have realistic expectations for kidney recovery. While suppressing the bone marrow clone stops new damage, it cannot always fix damage that has already occurred.

• Interstitial Fibrosis: If your kidney biopsy showed significant interstitial fibrosis (advanced scarring) or tubular atrophy, the kidneys may not be able to regain full function even after the protein is suppressed ^[6].
• Advanced Disease: If the disease was active for a long time before diagnosis, the kidneys may reach a point of severe impairment where dialysis is necessary despite successful hematologic treatment ^[12][13].

The focus of treatment is often on preservation—keeping your current kidney function from getting any worse—rather than a complete “cure” of the kidney damage ^[14].