Gross, Gerald G.

Abstract Background Anthracycline use in metastatic breast cancer (MBC) is hindered by cumulative exposure limits and risk of cardiotoxicity. Pixantrone, a novel aza-anthracenedione with structural similarities to mitoxantrone and anthracyclines, is theorized to exhibit less cardiotoxicity, mainly due to lack of iron binding. We conducted a randomized phase II study to evaluate the efficacy and safety of 2 dosing schedules of pixantrone in patients with refractory HER2-negative MBC. Methods Intravenous pixantrone was administered at 180 mg/m2 every 3 weeks (group A) versus 85 mg/m2 on days 1, 8, and 15 of a 28-day cycle (group B). Primary endpoint was objective response rate (ORR) and secondary endpoints included progression-free survival (PFS), median 6-month PFS, overall survival (OS), safety, quality of life, and serial assessment of circulating tumor cells. A 20% ORR was targeted as sufficient for further testing of pixantrone in this patient population. Results Forty-five patients were evaluable, with 2 confirmed partial responses in group A and 1 in group B. The trial was terminated due to insufficient activity. Overall median PFS and OS were 2.8 (95% confidence interval [CI]: 2.0-4.1) and 16.8 (95% CI: 8.9-21.6) months, respectively. Notable overall grade 3-4 adverse events were the following: neutrophil count decrease (62%), fatigue (16%), and decrease in ejection fraction (EF) (4%). Conclusion Pixantrone has insufficient activity in the second- and third-line MBC setting. It appears, however, to have limited cardiotoxicity. (ClinicalTrials.gov ID: NCT01086605).

1083 Background: Pixantrone (Pix) is a novel aza-anthracenedione with structural similarities to mitoxantrone and promising activity against non-Hodgkin’s lymphoma. Due to the lack of iron binding it is theorized to exhibit less cardiotoxicity than the anthracyclines. Methods: N1031 is a phase II RCT of 2 schedules of Pix, in pts with MBC. Group A pts received 180mg/m2 IV q3 wks, and group B pts 85mg/m2 IV on days 1, 8, 15 q4 wks. Eligibility included prior exposure to anthracyclines and/or taxanes, and 1 to 3 regiments in the metastatic setting (minimum of 2 if no prior adjuvant therapy given). Due to lack of long term cardiac safety data no more than 12 cycles were allowed. Frequent cardiac imaging was performed per protocol. Primary endpoint was RR and secondary endpoints included PFS, OS, safety, and QOL. Planned sample size was 25 pts per group. Results: In total 46 pts were evaluable (23 per group), mean age 55.5 yrs (range 38-79), 37% PS 0, 52% PS 1, and 11% PS 2. 80% of pts had prior exposure to doxorubicin, 72% had prior (neo)-adjuvant therapy, 76% were ER+ and 57% received prior HT. Number of prior metastatic regiments was: 1 (28%), 2 (61%) and 3 (11%). Most common adverse events (%) of any grade were: alopecia (74), anemia (74), fatigue (85), nausea (67), ANC decrease (87), and skin disorder (41). Grade 3-4 adverse events (%) at least possibly attributed to Pix and occurring in at least 2 pts were: ANC decrease (57), fatigue (9), increased AST (4%). One pt from each group (4%) had a grade 3 decrease in EF. There were no major differences between the two groups except for more oral mucositis in group A (35% vs 4%). Median number of cycles was 3 in group A (range 1-12) and 2 in group B (range 1-8). There was only 1 confirmed tumor response per group (4%,95% CI: 0.1-22%) prompting early termination of the trial. The median PFS was 2.7 mo (95% CI: 1.8-3.8), and the median OS was 8.9 mo (95% CI: 7.5-N/A). Conclusions: Pixantrone has insufficient activity in patients with MBC exposed to prior anthracyclines and/or taxanes. Adverse events were similar to prior experience with Pix. There were no major differences between the 2 schedules of administration. There was no significant cardiac toxicity seen in this trial. Correlative studies are underway.

1048 Background: Previous trials with p plus gem show significant antitumor activity in MBC. Nab-p has lower toxicity compared to p with similar therapeutic effects. This study assessed proportion of confirmed tumor responses and toxicity profile of this combination. Methods: Single stage phase II study enrolled patients (pts) with measurable MBC eligible for 1st line chemotherapy (chemo). Pts treated (tx) with nab-p 125 mg/m2 followed by gem 1,000 mg/m2 days 1 and 8 of 21 day cycle. Dose modifications allowed for both drugs. Primary endpoint was proportion of confirmed responses; complete response (CR), partial response (PR) by RESIST criteria on two consecutive evaluations at least 6 weeks apart. 41 evaluable pts required to test the null hypothesis that the confirmed response rate was at most 40% against the alternative of at least 60%. Results: 50 pts enrolled 11/05 to 5/06. Median age 56 (29–86). 40 pts (80%) visceral disease, 34 (68%) ER positive, 28 (56%) PR positive, 1 (2%) HER2 positive, 1 (2%) prior trastuzumab treatment (tx). 25 (50%) had prior adjuvant chemo, including 15 (30%) prior taxane. Median follow-up 7 mos (3–12). Median of 6 cycles of tx completed (1–15). 41 pts discontinued tx, due to progression (41%), pt refusal (27%), adverse events (17%), alternate tx (7%). Confirmed response rate 48% (95% CI: 34–63%): 4 CR, 20 PR. Median duration of response 6.6 mos (95% CI: 5.7, not reached), median progression-free survival (PFS) 7.9 mos (95% CI: 5.3–9.3). Rate of overall survival (OS) at 6 mos 91% (95% CI: 84–100%), 6 month PFS 58% (95% CI: 45–74%). Median OS not reached. 30 pts required dose delays on total of 52 cycles, mostly due to hematologic AEs. 9 pts (19%) had grade (gr) 4 adverse event (AE), 32 (67%) had maximum gr 3 AE. Most common gr 3/4 AEs: neutropenia (52%), fatigue (26%), anemia (14%), dyspnea (14%), thrombocytopenia (12%). Four pts had gr 3 neuropathy. Conclusions: Nab-paclitaxel in combination with gem has clear activity in patients with MBC. Manageable hematologic, but no other significant toxicities. Study ongoing to correlate efficacy with caveolin-1 levels with results expected Spring 2007. Follow up study of this combination with an anti-angiogenesis agent is in development. No significant financial relationships to disclose.

Background: Bevacizumab (BEV), a monoclonal antibody against vascular endothelial growth factor-A (VEGF-A), is a standard component of medical therapy of metastatic colorectal cancer (mCRC). Activation of alternative angiogenesis pathways has been implicated in resistance to BEV. This phase II study examines the activity of combined vertical blockade of VEGF signaling with sorafenib and BEV as salvage therapy in patients with progressive disease (PD) on all standard therapy in mCRC. Methods: mCRC patients with documented PD on standard therapy, received sorafenib (200 mg orally twice daily, days 1–5 and 8–12) and BEV (5 mg/kg intravenously, day 1) every 2 weeks. Primary endpoint was 3-month progression-free survival (PFS) rate and secondary endpoints were overall survival (OS), response rate (RR), safety, and feasibility. Results: Of the 83 patients enrolled, 79 were evaluable. Of these, 42 (53%) were progression-free at 3 months. Median PFS was 3.5 months and median OS was 8.3 months. One patient had a partial response and 50 patients (63.3%) had at least one stable tumor assessment. Of 79 evaluable patients, 54 (68%) experienced grade 3/4 adverse events (AEs) at least possibly related to treatment. Most frequent grade 3/4 AEs were: fatigue (24.1%), hypertension (16.5%), elevated lipase (8.9%), hand-foot skin reaction (8.9%), diarrhea (7.6%), and proteinuria (7.6%). Reasons for treatment discontinuation were PD (72%), AEs (18%), patient refusal (8%), physician decision (1%), and death (1%). Conclusions: The combination of BEV and sorafenib as salvage therapy in heavily pretreated mCRC patients is tolerable and manageable, with evidence of promising activity. ClinicalTrials.gov identifier: NCT00826540, URL: http://clinicaltrials.gov/ct2/show/NCT00826540