Have Clinicians Adopted the International Uniform Response Criteria (IURC) for Multiple Myeloma (MM)? Adherence to the IURC for Posttransplant Evaluations In Patients with Multiple Myeloma
Authors: Utz Kenneth , Neumon Bonita , Frye Brenda L. , Chao Ju-Hsien , Toro Juan , Haile David , Freytes Cesar 
Published: October 2019

Abstract
Abstract 84

Background:
The introduction of novel agents and the frequent use of autologous hematopoietic stem cell transplantation (AHSCT) have increased the frequency and magnitude of responses in patients with MM. There is increasing evidence that the magnitude of response influences the outcome of patients with MM. Furthermore, the availability of more sophisticated tests including serum free-light chains (SFLC) allow for a more accurate characterization of the magnitude of response. Previous response criteria were not stringent enough to accurately distinguish magnitudes of response, in particular complete response. To address this need, the International Myeloma Working Group (IMWG) proposed guidelines in July 2006 defining an IURC for patients with multiple myeloma. These criteria define the tests necessary to evaluate patients depending on the magnitude of the response and also incorporate the SFLC assay. However, there is currently limited information regarding the adherence of these guidelines by the clinical community.

Study Purpose:
To determine adherence to the IURC during post AHSCT in patients with MM.

Methods:
We performed a retrospective analysis of all patients who underwent AHSCT at our institution for MM from January 2007 to December 2009. This study time interval was selected because it allowed 6 months for dissemination of the IURC among the oncologic community and also allowed us to assess response evaluations up to 180 days posttransplantation. Posttransplant evaluations were performed by the referring program. Specific instructions regarding tests necessary for the posttransplant day 100 evaluations were provided by our program. Referring physicians decided which tests to order for the posttransplant evaluations. The response evaluations performed 100 days and 180 days posttransplantation were reviewed. All tests performed during the response assessment were recorded and the adherence to the IURC was determined. In particular, the assessment of CR as defined by the IURC guidelines was scrutinized. Furthermore, any additional clinical tests performed as part of the response assessment that were not recommended by the IURC were also recorded. Adherence to the IURC was considered met if all recommended tests were performed at each evaluation. Obtaining additional tests during the evaluation did not affect IURC adherence determination.

Results:
A total of 103 patients underwent AHSCT during the study period. Four patients were ineligible due to death within 100 days posttransplantation. Of the 99 patients who comprised the study group, 83 (84%) did not have evaluations that adhered to the IURC. Of evaluations not adhering to the IURC, the most common test omitted was urine protein electrophoresis (69/83; 83%). Nearly half (37/83; 45%) of evaluations not adhering to the IURC had an additional test omitted other than urine protein electrophoresis, including serum protein electrophoresis (17/83; 20%), bone marrow biopsy (12/83; 14%) and SFLC (21/83; 25%). Of all evaluations, a majority (62/99; 63%) included at least one test not recommend in the IURC. The additional tests consisted of β2 microglobulin (28/99; 28%), quantitative immunoglobulins (44/99; 44%) and serial SFLC in the presence of measurable disease (28/99; 28%).

Conclusion:
Only 16% of patients with multiple myeloma underwent posttransplant evaluations that adhered to the IURC guidelines. This finding suggests that community physicians have not embraced these guidelines. Laboratory tests not included in the IURC are frequently obtained despite the fact that they do not provide additional clinical information and increase the cost of care of patients with MM. Additional studies should be performed to determine the barriers to the use of IURC as defined by the IMWG.

Disclosures:
No relevant conflicts of interest to declare.