[Cancer and the Kidney: A Deadly Embrace].

A deadly embrace occurs between cancer and chronic kidney disease. The estimation of kidney function in cancer patients is of utmost interest due to its direct impact on chemotherapy dosing, selection, and eligibility for chemotherapeutics. Overestimating kidney function (determined as estimated glomerular filtration rate -eGFR) can lead to overdosing and drug toxicity, while underestimating kidney function can prevent patients from receiving novel therapies. Notably, the current measures of eGFR are not validated in transplanted patients yet. The field of onconephrology ranges from nephrotoxicity of existing and novel therapeutics, paraproteinemias, and cancer-associated electrolyte imbalance, fluid and acid-base disturbances, the effects of the destruction of cancer cells, and acute and/or chronic kidney injuries. Recently, the therapeutic armamentarium has been enriched with new agents that interfere with specific proteins involved in oncogenesis. These are the so-called target therapies, which although acquired as "targeted" therapies do not have absolute specificity and selectivity and tend to inhibit multiple targets, often involving the kidney. Renal biopsy may be critical in managing these adverse effects. Moreover, primary hematological and oncological disorders can have significant kidney implications in the form of glomerular or nonglomerular diseases presenting with proteinuria, hematuria, hypertension, and kidney function decline, specifically including cast nephropathy or systemic light chain amyloidosis, and paraneoplastic glomerulopathies that occur as a result of occult malignancy, such as Membranous Nephropathy and Minimal Change disease.

[Management of the Oncological Patient with Chronic Renal Failure].

Cancer is a leading cause of death in people with chronic kidney disease (CKD). The incidence of CKD in patients with cancer is higher than in the non-cancer population. Across various populations, CKD is associated with an elevated risk of cancer incidence and cancer death compared with people without CKD, although the risks are cancer site-specific. The potential mechanisms for the increased risk of cancer observed in CKD, include patient factors, disease, and treatment factors. CKD has also a major impact on the treatment of cancer patients. The kidney is the primary route of elimination of many anticancer drugs. Dosing of anticancer agents according to kidney function is essential to avoid undertreatment and toxicity. Because of the systemic exclusion of patients with severe kidney dysfunction from clinical cancer trials, data are lacking to guide dosing of anticancer drugs in patients with chronic kidney disease. As a consequence, many therapies are denied to CKD patients due to their possible toxicities. An orchestrated effort by all stakeholders is required to fill the knowledge gap and improve the outcome of cancer patients with kidney dysfunction.

[Renal Side Effects of Novel Molecular Targeted Oncologic Agents].

The introduction of innovative therapies has changed the scenario of complications. The delay in the recognition of kidney adverse effects is partly due to the timing of the development of the kidney damage which occurs later than the observation period of registration studies, and partly to the exclusion of patients with known kidney impairment from registration trials. Renal disease has a significant impact on the management of cancer patients and often leads to discontinuation of therapy. Histological evaluations of kidney disorders induced by targeted/immunotherapy are very limited. Renal biopsy is critical for the management of renal toxicities and should be especially encouraged for patients showing adverse renal effects to novel cancer agents. We recently examined the histological features of patients treated with new cancer agents who underwent renal biopsy for new onset renal failure and/or urinary abnormalities. The cohort included 42 patients. The most frequently administered therapies were immunotherapy (54.8%) and anti-angiogenic treatments (45.2%). The most common adverse effect was tubular interstitial nephritis in the first group and thrombotic microangiopathy in the second one. Based on histological findings, definitive discontinuation of treatment could be restricted to a very limited number of patients. All of them had anti-VEGF-related TMA. Treatment discontinuation was unneeded in patients treated with ICIs. In patients treated with multidrug therapy, the histological findings made it possible to identify the weight of drug-related specific injury. Based on this data, renal biopsy should be considered in every cancer patient who develops urinary abnormalities or shows a worsening of renal function during treatment with immunotherapy or targeted therapy.

[Management of Cast Nephropathy].

Myeloma cast nephropathy is the most common cause of acute kidney injury in patients affected by multiple myeloma. The mainstay of management of cast nephropathy is the clone-based therapy by reducing production and thereby precipitation of light chains. Adjuvant therapy consists of inducing high urine volume flow and alkalinisation, where possible. Extracorporeal removal of light chains is still debated and the advantages of these procedures are not established. The use of safe and low expensive membranes may encourage their use and address their utility.