What signs of PRCA may be observed in a CRF patient treated with epoetins?

A sudden onset of persistent, severe anemia (normochromic, normocytic) with normal granulocyte and platelet counts. The anemia is not responsive to increasing doses of epoetin, and patients become transfusion dependent.

Could all Lack of Effect (LOE) cases reported be associated with an immunogenic reaction to epoetins?

No. Only a very small number of patients receiving epoetins experience LOE. The most common cause of LOE is iron deficiency. Some additional causes may include blood loss through dialysis, infections, inflammatory process, occult bleeding, folic acid or vitamin B-12 deficiency, marrow fibrosis or aluminum toxicity. These causes represent much more common reasons for LOE and should be ruled out first before considering an immune response. The product label is a good reference for additional information about investigating non-response to epoetin therapy.

What types of antibodies might be seen in patients treated with epoetin?

There are two types of antibodies. One type is referred to as non-neutralizing. These antibodies do not appear to cause a lack of clinical effect. The second type of antibody is referred to as neutralizing, so named because the antibody renders naturally occurring EPO and epoetin drugs inactive. Neutralizing antibodies cause epoetin therapy to fail.

Has PRCA due to anti-EPO antibodies been seen in oncology patients?

As of 31 March 2002, PRCA cases with anti-EPO antibodies have only been confirmed in patients with chronic kidney disease. The majority of these cases involved EPREX/ERYPO.

What do most physicians know about PRCA?

Physicians have certainly heard of the term, and probably know it mostly as a very rare phenomenon that they have not encountered in clinical practice. There are just a few literature reports over the past 10 years. Interest and information have increased in the past 6 months. In November 2001, Janssen-Cilag (and Ortho Biotech) presented PRCA case reports to regulatory authorities worldwide, and to customers. EPREX/ERYPO prescribing information was updated in 4th quarter 2001. In many countries, the Company instituted a "Dear Doctor Letter" to coincide with an update to the EPREX/ERYPO label in 4th quarter 2001. The Sales Force actively has advised physicians of our observations and label change since November 2001. A slide presentation was released for use in presenting PRCA information to customers. Also, the New England Journal of Medicine article (Casadevall, et al, February 14, 2002) brought it to the attention of many clinicians. PRCA remains a rare event observed in a small number of CRF patients. Because of the rare nature of this disorder, most clinical nephrologists may have never managed a patient with this condition.

Who are we working with as outside experts?

There are a number of medical opinion leaders and scientific advisors assisting us. There is a Global Advisory Board comprised of key opinion leaders from Europe, Canada, Australia and USA who have been retained to assist us. The Advisory Board is multi-disciplinary and comprised of nephrologists, hematologists and immunologists. Other consultant arrangements have also been established.

Is there some other characteristic that could make certain patients more susceptible to developing PRCA when treated with epoetins?

The first characteristic is all reported cases to date have a diagnosis of CRF. With so few reported cases of PRCA, it is very difficult to detect special characteristics which make a patient more susceptible to developing PRCA. This question is also asked in the case-by-case investigations ongoing at this time.

In CKD patients who had been treated with EPO, how long did it take before PRCA developed?

The median duration of therapy prior to symptoms is 9-10 months cases. Treatment periods ranged from 2 to 111 months before EPO-related PRCA developed.

Is there an association between PRCA and patient care or other medications administered to these patients?

As there are very few reported cases, it is very difficult to find associations with patient care or other medications. However, subcutaneous (s.c.) administration is predominant in the reported cases where data are available. The case-by-case investigation is under way, and this question is part of the analysis currently being conducted and it is also to be analyzed in a follow-up study of all reported cases.

Is there an association between PRCA and product handling?

When biologic products such as EPREX® are subjected to stress conditions, there remains the potential for protein aggregate formation. Protein aggregation is a known cause for immunogenic reactions. It therefore remains important to follow storage and handling guidelines described in the label. The case-by-case investigation of PRCA cases will evaluate this issue. We are also looking into handling practices in the supply chain (distribution network) with the intent to provide educational support and ensure entire supply chain understands and follows necessary handling procedures. 19.

Are EPREX/ERYPO and PROCRIT the same drug?

No. They are made at different manufacturing sites and have different formulations. However, both are known by the same chemical name, epoetin alfa. PROCRIT and EPOGEN are epoetin alfa brands manufactured by Amgen Inc. and marketed by Ortho Biotech Products, L.P. and Amgen respectively for different indications. EPREX/ERYPO are the brand names used to market epoetin alfa brands manufactured by our Company and marketed by Ortho Biotech and Janssen-Cilag outside of the United States.

Does the route of administration of EPREX/ERYPO have an impact on the development of immunogenicity or PRCA?

The literature suggests that injecting proteins under the skin (sub-cutaneous route (SC)) has higher immunogenic potential than injecting directly into the vein (intravenous route (IV)). Of the reported PRCA cases, the majority are patients treated with EPREX/ERYPO by SC route.

Is EPREX/ERYPO considered a safe product when administered by SC route?

Subcutaneous route is considered a safe route of administration. However, the risk-benefit of SC should be evaluated in light of the PRCA case reports. Patients who can be treated with epoetins via IV route (e.g., hemodialysis patients) have an option that the physician should consider based on risk-benefit.

If a patient develops PRCA and anti-EPO antibodies to one type of epoetin, can they simply be switched to a different brand?

No. There is clinical evidence suggesting anti-EPO antibodies cross react with all epoetins and darbepoetin. It is recommended that treatment with all erythropoietins be discontinued.

What is said about Immunogenicity in the NeoRecormon label?

There was an update to their label in September 2001: "In very rare cases, neutralizing anti-erythropoietin antibodies with or without pure red cell aplasia (PRCA) occurred during r-HuEPO Therapy"

What is said about Immunogenicity in the ARANESP label?

The EMEA document (European Public Assessment Report) notes the "theoretical potential" for antibody development. Amgen has been required by both USA and the EU to conduct post-Marketing clinical studies to determine if antibody development occurs in patients treated with ARANESP. In the USA, there are specific statements in the ARANESP Package Insert:

"The incidence of antibody development in patients receiving ARANESP has not been adequately determined….High-titer antibodies were not detected, but assay sensitivity may be inadequate to reliably detect lower titers. …comparison of the incidence of antibodies to ARANESP with the incidence of antibodies to other products may be misleading. Erythrocyte aplasia has been reported on rare occasions in patients treated with other recombinant erythropoietins. Due to the close relationship of ARANESP to endogenous erythropoietin, such a response is a theoretical possibility with ARANESP treatment, but has not been observed to date."

NOTE: There have been no reported cases of antibody development in patients receiving ARANESP to date. The EMEA document (European Public Assessment Report) notes the "theoretical potential" for antibody development. Amgen is required to conduct post-marketing clinical studies to determine if antibody development occurs in patients treated with ARANESP, both in USA and EU.

How do laboratories test for the presence of antibodies?

There are various laboratory tests (assays) that will detect whether or not antibodies are present. One is called ELISA (enzyme-linked immunosorbent assay). Another is referred to as IP (immunoprecipitation). A third technique utilizes the Western Blot procedure. All tests can detect the presence of anti-EPO antibodies, but there is scientific controversy about the sensitivity, specificity and accuracy of each of these tests. From internal investigations, IP appears to offer the best combination of accuracy and sensitivity.

How can a physician request an Anti-EPO antibody assay?

The Company will pay for anti-EPO antibody testing for any physician who has reported an adverse event and who wishes to have the test performed. Patient consent must be obtained prior to sample collection. Timing of sample collection is also important. Contact Janssen Pharmaceutica for further information.

Are you conducting any trials now looking for anti-EPO antibody?

Yes. An international Phase 4 study (INT-77) was initiated in June 2000. One purpose was to establish background incidence of anti-EPO antibodies occurring in CRF patients with at least 6 months of exposure to r-HuEPO. Serum samples have been collected from 278 patients in 8 countries. To date, using an IP assay, no samples have shown antibodies. Other studies will include screening for antibody (baseline and during study).

How common are false-positive anti-EPO antibody test results?

They are theoretically possible. Autoimmune diseases may be associated with assay result interference (e.g., Systemic Lupus Erythaematosis, Rheumatoid Arthritis) that could cause erroneous results. However, false-positive results have not been observed in our extensive laboratory experience.

How common are false-negative anti-EPO antibody test results?

They can occur mostly due to timing of serum sample collection.

What are the treatment options for patients with CKD who have anemia but who do not respond to immunosuppressive therapy?

Supportive blood transfusions are the best option. The possibility of renal transplant also exists. Casadevall (2002) notes one (1) PRCA patient in whom anemia was corrected after renal allograft.

If the bone marrow examination shows that the anemia is due to PRCA, what should be done?

Treatment may involve use of immunosuppressive drugs, starting with corticosteroids. In patients not responsive to steroids, cyclosporine, immunoglobulins (IV-IG) or cytotoxic drugs may be used by themselves or in combination with glucocorticoids. The response rate to immunosuppressive drugs is estimated to be 30-55%.

Consideration should also be given to collection of blood samples for anti-EPO antibody determination.

Has anyone ever died from PRCA or anti-EPO antibody development?

As of March 31, 2002, one (1) patient death is attributed to PRCA by the reporting physician. The relevance of epoetin treatment or anti-EPO antibodies to cause of death has not been established.

What steps should a physician follow if a patient experiences LOE?

• Rule out potential causes of anemia (iron, folate or B12 deficiency, aluminum toxicity, infection, inflammation). Follow guidelines in EPREX/ERYPO label.

• If no causes can be identified, consider doing a bone marrow biopsy examination (BM).

• If PRCA is confirmed through bone marrow biopsy examination, therapy with all erythropoietin products should be discontinued until the etiology of PRCA is determined.

• A test for anti-EPO antibodies should be considered.

• If an immune response to EPREX/ERYPO cannot be ruled out, therapy with

• all erythropoietin product should be permanently discontinued.

• Medical treatment procedures for PRCA should be initiated.

• Report this case to the local Medical Affairs Department for further investigation.

If the more common causes of LOE have been ruled out, what should the physician do?

Patients with sudden onset of anemia during treatment with epoetins should be evaluated for the cause of LOE. If a diagnosis of PRCA is established (bone marrow biopsy evaluation is recommended), treatment with all erythropoietins should be discontinued until etiology of PRCA is determined. Patient serum should be collected for determination of anti-EPO antibodies. (Contact Medical Affairs).

If a patient treated with epoetin develops signs of anemia and, through a bone marrow biopsy evaluation, is found to have PRCA, does that mean he will automatically have anti-EPO antibodies?

No. Of the cases reported and tested so far, not all bone marrow-confirmed PRCA cases had anti-EPO antibodies. However, it is highly likely that a patient with LOE and confirmed PRCA will demonstrate anti-EPO antibodies at some time.

If a patient shows signs of LOE and it is found to be PRCA, would it help to increase epoetin dose?

No. Increasing the dose of epoetin does not help the LOE situation if the cause of LOE is PRCA due to anti-EPO antibodies.