Citations

2534 Background: The Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 were derived from an international collaborative effort supported by data from clinical trials (16 studies, 9147 patients) on cytotoxic chemotherapy (CT), providing a standard tool for response assessment. RECIST’s role has been questioned for TCA. Using a pooled individual patient database (IPD) from clinical trials performed by industry and cooperative groups, we assessed whether modifications to RECIST are required to evaluate antitumor activity of TCA. Methods: Data were collected from phase 2 and 3 clinical trials testing TCA in solid tumors. To study the occurrence of mixed responses, the variability of response of lesions within patients was studied. Furthermore, response was correlated with survival through landmark analyses and time dependent Cox models. Results: Clinical data were obtained from 23,259 patients, mainly with lung (36%), colorectal (28%) or breast cancer (11%). 15,620 patients (67%) received a TCA, mainly transduction or angiogenesis inhibitors, either as single agent (37%) or combined with other TCAs (7%) or CT (56%); 28% received CT only and 5% best supportive care or placebo. Within-patient variability reduced as the number of lesions used for response assessment increased, and did so similarly for TCAs (+/- CT) and CT. Mixed responses seemed to occur similarly across these treatment categories as well. Landmark analyses showed improving overall survival by % tumor shrinkage and a clear distinction between the effect of tumor shrinkage and progressive disease (PD) according to RECIST 1.1. This was confirmed by time dependent analysis. In addition target lesion growth showed no marked improvement in overall survival prediction over and above the other components of RECIST 1.1 PD (new lesions, non-target PD), regardless of treatment (TCA, CT or both) received. Similar results were seen focusing on major tumor types and classes of TCA. Conclusions: Using a large IPD dataset we demonstrated that RECIST 1.1 performs equally well for response assessment of TCA as for CT. No modifications are required.

11503 Background: Cancer Associated Macrophage-Like cells (CAMLs) are a recently described circulating stromal cell subtype commonly found in the peripheral blood of patients in all stages of solid malignancies and in a variety of cancer subtypes. However, while their biological association to cancer is being studied, their clinical utilization as it relates to cancer prognosis has not been evaluated. Methods: A two year prospective study was undertaken to evaluate the relationship of CAMLs and overall survival (OS) in 6 solid tumor types. The single blind multi-institutional study consisted of 269 stage I-IV patients; breast (n = 57), esophageal (n = 21), prostate (n = 43), pancreatic (n = 59), lung (n = 54), and renal cell (n = 35), in treatment (n = 134) and untreated baseline (n = 135). 7.5mL of whole blood was filtered by CellSieve microfiltration assay and CAMLs enumerated, as previously described. Patients were grouped by CAML number ( < 6 or ≥6) and by size ( < 49 or ≥50 µm) to evaluate hazard ratios (HR) by censored univariate & multivariate analysis. Results: CAMLs were identified in 93% of samples, averaging 8.2 CAMLs/7.5mL blood sample, and found in all 6 cancers at baseline and during treatment. Average CAML number was associated with disease stage and CAML positivity was 4.4 & 80% (Stage I), 4.7 & 93% (Stage II), 9.3 & 98% (Stage 3), 12.1 & 97% (Stage IV). Univariate analysis of patients (n = 269) stratified by ≥6 CAMLs had reduced OS (HR = 1.8, 95%CI 1.1-2.9, p = 0.03). Further, CAML size also had reduced OS in patients with ≥50 µm CAMLs (HR = 2.7, 95%CI 1.8-4.0, p < 0.0001). Conclusions: Our data suggests that in solid malignancies, CAML number and size appear to clinically correlate with OS in early and late stage disease. Given these results relating CAMLs with OS, further analysis is warranted to determine if CAMLs can serve as a clinically-relevant blood-based marker.

e19532 Background: The diagnosis of amyloidosis requires histological confirmation of Congo-red (CR) deposits. The tissue source is preferably fat and/or bone marrow biopsy, but at times organ biopsy is required. Methods: We studied 612 patients with systemic light chain amyloidosis to characterize the tissues used to establish the diagnosis Results: The median number of tissue samples biopsied for CR staining was 3. Ninety-five percent of bone marrow (BM) biopsies were stained for CR, while 79% of patients had fat aspiration performed for CR staining. Overall, 76% of patients underwent both procedures. CR stain sensitivity was 69% in BM samples, 75% in fat aspiration and in 89% for both sources combined. CR stain sensitivity was 97-100% for heart, renal and liver biopsies. 42% of patients with renal involvement, 21% of patients with liver involvement and 13% of patients with heart involvement underwent organ biopsy, when a less invasive safer biopsy would have established the diagnosis. Predictors of need for organ biopsy were male sex, limited organ involvement and lack of fat aspiration (Table). Conclusions: Fat aspiration is underutilized for histologic confirmation of amyloidosis. Organ biopsies (particularly renal biopsies) were performed at a high rate, which represents a failure to recognize the disease (i.e. failure to screen with a light chain assay etc.). Early awareness of amyloidosis in the differential diagnosis of patients with organ dysfunction may lead to fewer unnecessary organ biopsies [Table: see text]

8038 Background: Daratumumab-based Combination Therapies (DCT) with bortezomib (V)/ lenalidomide (R)/ pomalidomide (P) and dexamethasone (d) showed exceptional activity in RRMM in trials. Experience outside of trials since the approval of Daratumumab (D) in 2015 is limited. Methods: RRMM pts seen at Mayo Clinic, MN from 12/2015 -12/2016 were reviewed. Pts who received ≥ 1cycle of DCT were included. Time-to-event analyses were done from date of starting DCT. Common terminology criteria for adverse events v4.0 were used to grade toxicities. Results: Of 130 pts, 59% were males and median age at DCT initiation was 67 (43-93) years, ECOG performance score was ≥2 in 29%. Pts were classified as mSMART high (22%), intermediate (22%) or standard (56%) risk. Median time from diagnosis to initiation of DCT was 51.3 (5-156) months (m), and median number of prior therapies was 4 (1-14). 14% of pts were refractory to prior D monotherapy. Fifty-three (41%), 34 (26%) and 25 (19%) received DPd, DRd and DVd respectively. Eighteen (14%) pts received ‘other’ DCT. Median time to first response (≥ PR) was 3.1 m (95% CI 2.1-4.6). Overall response rate was 46%, [CR-2%, VGPR-18%, PR-26%]. Minimal response was seen in 17%, with clinical benefit rate of 62%. Median estimated follow up from initiation of DCT was 5.5 m (CI 4.2-6.1). The median duration of response was 6.1 m [CI 5.1- not reached (NR)]. Median progression free survival (PFS) was 5.5 m (CI 4.1-7.8) and median time to next therapy (TTNT) was 5.9 m (CI 4.6-9.4). Median PFS for DPd, DRd, DVd and other DCTs were 4.6 (CI 2.7-NR), 7.8 (CI 5-NR), 3.9 (CI 2.1-NR) and 3.9 (CI 2.8-8.2) m, respectively (p = 0.3). Median PFS for quadruple refractory (n = 28) MM was 2.8 m (CI 2.2-5.3) vs 5.9 m (CI 4.9-NR) for the rest (p < 0.01). Median overall survival (OS) from DCT was NR (CI 11.4-NR). Grade 3 or higher hematological toxicities were seen in 42% of pts. Other toxicities included infections (37%), fatigue (31%), infusion reactions (16%) and diarrhea (10%). Conclusions: DCT are effective in RRMM, but the PFS remains short particularly in quadruple refractory pts, reflecting the challenges encountered in managing heavily-pretreated, and often less fit patients, in routine practice.

8032 Background: Human adipocytes can contribute directly to the in vitro growth and progression of multiple myeloma (MM) cell lines. Clinically, an elevated body mass index (BMI) has been associated with an increased risk of MGUS and a shorter time to progression (TTP) of MGUS to MM. However, the impact of BMI on the risk of early progression to MM from a more advanced plasma cell disorder such as smoldering MM (SMM) remains unknown. Methods: This study included patients (pts) with a known or new diagnosis of SMM evaluated at the Mayo Clinic, Rochester from January 2000-December 2010. Pts were classified based on their BMI as: normal (< 25) and elevated (>/= 25) BMI. Progression to symptomatic MM was defined by the development of hypercalcemia, renal insufficiency, anemia or lytic bone lesions. Results: There were 306 pts with a diagnosis of SMM who were included in this analysis. The median follow up was 106 months. There were 203 (66%) pts who progressed to symptomatic MM at last follow up. The median BMI of the group was 27.5 (Range: 17.2 – 56.4). There were 228 (75%) pts with an elevated BMI. There were 76 (28%) pts who had myeloma defining events (MDEs) such as a serum free light chain ratio > 100 or > 60% clonal bone marrow plasma cells at initial evaluation. MDEs were present in 17% and 33% of pts with a normal and elevated BMI respectively (P = 0.011). The median TTP of SMM to MM in pts with a normal and elevated BMI was 64 and 36 months respectively (P = 0.0006). The 2-year progression rate of SMM to symptomatic MM in pts with a normal and elevated BMI was 16% and 42% respectively (P < 0.0001). Upon limiting the analysis to only SMM pts without MDEs at initial evaluation (N =187), the 2-year progression rate to symptomatic MM with a normal and elevated BMI was 15% and 33% respectively (P = 0.013). In a multivariable model, only elevated BMI (P = 0.004) and increasing clonal bone marrow plasma cells (P = 0.001) was statistically significant in predicting for a 2-year progression to MM. Conclusions: SMM pts with an elevated BMI appear to have a higher risk of early progression to MM than those with a normal BMI. This study provides evidence of a potentially modifiable risk factor for the progression of SMM to MM and warrants confirmation in larger studies.