Citations

10537 Background: Lorvotuzumab mertansine (IMGN901; LM) is an antibody-drug conjugate, linking anti-mitotic agent (DM1) to an anti-CD56 antibody. Preclinical data show effects in Wilms tumor (WT), rhabdomyosarcoma (RMS), and neuroblastoma (NBL). Synovial sarcoma (SS), MPNST and pleuropulmonary blastoma (PPB) also express CD56. A phase 2 trial assessing the efficacy and tolerability of LM administered at the adult recommended phase 2 dose (RP2D) was conducted in children with relapsed tumors. Methods: LM (110 mg/m2/dose) was administered IV on days (d) 1 and 8 of 21 d cycles, with dexamethasone pre-medication. The tolerability of LM was assessed in 6 patients prior to trial activation group-wide. Dose limiting toxicity (DLT) was assessed using CTCAE. Response was assessed by RECIST. Pharmacokinetics (PK) were obtained during cycle 1. Peripheral blood CD56-positive cells were measured d1 and d8 pre-dose. Tumor CD56 expression by immunohistochemistry in archival tissue was scored (0-3+). Results: Sixty-two patients were enrolled. The median (range) age was 14.3 y (2.8–29.9); 35 were male. Diagnoses included WT (17), RMS (17), NBL (12), SS (10), MPNST (5) and PPB (1). One patient was ineligible due to lack of measurable disease. Of 61 eligible patients, 47 were evaluable for toxicity, 50 for response, 50 for tumor CD56 expression; and 18 consented to optional PK. Five patients experienced 9 DLTs: hyperglycemia (1), colonic fistula (1) with perforation (1), nausea (1) with vomiting (1), increased ALT (2 in cycle 1; 1 in cycle 2 with increased AST (1)). Non-dose limiting toxicities (Grade ≥3) attributed to LM included lymphopenia, anemia, vomiting, dehydration, hypokalemia, hyperuricemia, hypophosphatemia. Mean DM1 Cmax, t1/2 and AUC0-∞values were 922 ng/ml, 33 h and 27400 ng/ml*h, respectively. Tumor CD56 expression was 0 (8%), 1+(4%), 2+(12%), 3+(76%). LM and CD56 antibody PK, and response, will be reported. Conclusions: LM (110 mg/m2) is tolerated in children at the adult RP2D. Clinical trial information: NCT 02452554.

6531 Background: Annual mammography is recommended to screen residual breast tissue for new cancers and recurrent disease after treatment for early stage breast cancer. This study aimed to assess mammography rates over time in breast cancer survivors. Methods: We used administrative claims data from a large U.S. commercial insurance database, OptumLabs, to retrospectively identify privately- and Medicare Advantage-insured women with operable breast cancer who had residual breast tissue after definitive breast surgery between 2006 and 2015. We required coverage for at least 13 months following surgery. For each subsequent 13-month time period, we only included women without a loss of coverage, bilateral mastectomy, metastatic breast cancer diagnosis, or non-breast cancer diagnosis. We calculated the proportion of patients who had a mammogram during each 13-month period following breast surgery. We used multivariable logistic regression to test for factors associated with mammography in the first 13 months. Results: The cohort included 26,011 women followed for a median of 2.9 years (IQR 1.9-4.6) after surgery; 63.1% were less than 65 years of age, and 74.4% were white. In their first year of follow-up, 86% underwent mammography, but by year 7, this decreased to 73%. Fewer than 1% underwent MRI instead of mammography. In multivariable analysis, mammograms were less likely during the first year after surgery among women aged < 50 years (odds ratio [OR], 0.7; 95% confidence interval [CI], 0.6 to 0.8), African Americans (OR, 0.7; 95% CI, 0.7 to 0.8), patients who underwent mastectomy (OR, 0.7; 95% CI, 0.6 to 0.7), and patients residing in the Western part of the country (OR, 0.9; 95% CI, 0.7 to 0.9). Those with 1-2 comorbidities were more likely (OR, 1.1; 95% CI 1.1-1.2) than those with none to have a mammogram during that period. Mammography use did not differ significantly by year of diagnosis (2006-2015). Conclusions: Even in an insured cohort, a substantial proportion of breast cancer survivors do not undergo annual surveillance mammography. Mammography use falls as the time from the early stage breast cancer diagnosis increases. Understanding factors associated with lack of mammographic screening may help improve survivorship care.