Efficacy of panitumumab (pmab) vs. cetuximab (cmab) in patients (pts) with wild-type (WT) KRAS exon 2 metastatic colorectal cancer (mCRC) treated with prior bevacizumab (bev): Results from ASPECCT

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Background: The phase 3 ASPECCT trial of pts with chemorefractory WT KRAS exon 2 mCRC demonstrated that pmab was noninferior to cmab for overall survival (OS). A previous subgroup analysis of hazard ratios (HRs) suggested that pts who had received prior bev (any line, at any point before study start) in the pmab arm may have had better outcomes vs pts in the cmab arm (Price, 2014). Methods: Pts were randomized 1:1 to receive pmab or cmab. The subset of pts who had received prior bev were analyzed based on the final analysis of ASPECCT. Results: 999 pts were randomized and treated: 499 pmab and 500 cmab. The prior bev subset included 126 pts in the pmab arm (25%) and 132 pts in the cmab arm (26%). Pts in the pmab arm had longer median OS and progression-free survival (PFS) and higher objective response rates (ORR) compared with pts in the cmab arm. Results are shown (table). After adjustment for baseline covariates including ECOG performance status, number of metastatic sites, and baseline LDH, OS HR was 0.65 (95%CI=0.49-0.85) with pmab vs cmab in pts who had received prior bev. Pts in the pmab and cmab arms who did not receive prior bev had similar OS, PFS, and ORR. Post-progression antitumor therapy was similar between the pmab (47%) and cmab arms (52%) in pts who received prior bev. Conclusions: In ASPECCT, pts with WT KRASexon 2 mCRC who received prior bev-containing regimens may have derived greater benefit with pmab versus cmab monotherapy. Clinical trial information: NCT01001377. [Table: see text]

Outcomes by hypomagnesemia (hypomag) in the randomized phase III ASPECCT trial of patients (pts) with chemofractory wild-type (WT) KRAS exon 2 metastatic colorectal cancer (mCRC)

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Background: ASPECCT demonstrated that panitumumab (pmab) was noninferior to cetuximab (cmab) for overall survival (OS). Ad hoc analyses from ASPECCT suggested that hypomag was associated with better outcomes for pmab and cmab (Price 2015). However, results from the phase 3 NCIC CTG/AGITG CO.17 trial indicated hypomag at day 28 was associated with worse outcomes for cmab (Vickers 2013). Methods: Patients (pts) with chemorefractory WT KRASexon 2 mCRC were randomized 1:1 to receive pmab or cmab. Ad hoc analyses by hypomag were performed from the final analysis of ASPECCT at week 5, consistent with the NCIC CTG/AGITG CO.17 trial analysis (Vickers, 2013). Results: 999 pts were treated: 496 received pmab and 503 received cmab. Any grade hypomag was 29.0% and grade ≥3 was 7.3% in the pmab arm vs 19.3% and 2.8% in the cmab arm, respectively. In the pmab arm, 1.2% of pts discontinued treatment and 5% of pts had dose modifications due to hypomag vs 0.4% and 3% in the cmab arm, respectively. Efficacy results by hypomag are shown (Table). Conclusions: In ASPECCT, rates of hypomag were higher in the pmab vs the cmab arm. Pts who developed any grade hypomag with pmab or cmab had longer median OS compared with those pts who did not. Consistent with previous analyses, development of hypomag at week 5 was associated with worse median OS for cmab. Clinical trial information: NCT01001377. [Table: see text]

Randomized phase III study of panitumumab (pmab) vs. cetuximab (cmab) in chemorefractory wild-type (WT) KRAS exon 2 metastatic colorectal cancer (mCRC): Outcomes by hypomagnesemia (hypomag) in ASPECCT

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Background: ASPECCT met its primary endpoint of non-inferiority of overall survival (OS) of pmab vs. cmab. We evaluate outcomes by hypomag, an on-treatment, anti-EGFR related adverse event that develops due to the inhibition of EGFR function. Conflicting reports have suggested hypomag is associated with survival. Methods: Patients with previously treated WT KRAS exon 2 mCRC were randomized 1:1 to receive pmab or cmab. The primary endpoint was non-inferiority of OS. Progression-free survival (PFS) and objective response rate (ORR) were secondary endpoints. Patients were categorized ± any grade hypomag during the study and data analyzed by treatment arm. Analysis of Mg supplementation during hypomag was not conducted. Results: 999 patients were randomized and treated: 499 pmab, 500 cmab. Any grade hypomag was 28.8% and grade ≥3 was 7.3% in the pmab arm vs. 18.9% and 2.6% in the cmab arm, respectively. Median time to first hypomag onset was 82 days in the pmab arm and 57 days in the cmab arm. In the pmab arm, 1.0% of patients discontinued treatment and 5% of patients had dose modifications due to hypomag vs. <0.5% and 3% in the cmab arm, respectively. Results are shown (Table). Conclusions: In ASPECCT, rates of hypomag were higher in the pmab vs. the cmab arm. Patients who developed any grade hypomag with pmab or cmab had higher ORR, PFS, and OS compared with those patients who did not. Clinical trial information: NCT00788957. [Table: see text]

Prevalence and outcomes of patients (pts) with EGFR S492R ectodomain mutations in ASPECCT: Panitumumab (pmab) vs. cetuximab (cmab) in pts with chemorefractory wild-type KRAS exon 2 metastatic colorectal cancer (mCRC)

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Background: Mutations resistant to anti-EGFR treatment (tx), beyond those in RAS, have been reported and include EGFR S492R. We report results for pts with EGFR S492R mutations in the phase 3 ASPECCT trial. Methods: Pts were randomized 1:1 to receive pmab or cmab. Crossover was not allowed. The primary endpoint was non-inferiority of overall survival (OS). Secondary endpoints included progression-free survival (PFS), objective response rate (ORR) and safety. EGFR S492R was evaluated by digital droplet PCR in plasma samples collected pre-tx and post-tx (safety follow-up 4 wks after the last dose). Outcomes were analyzed by EGFR S492 status. Results: Of 999 pts randomized and treated, post-tx samples were available for EGFR S492 assessment from 53% of pts (261/496) in the pmab arm and 57% of pts (285/503) in the cmab arm. EGFR S492R was detected in 1% of pts in the pmab arm and 16% of pts in the cmab arm in post-tx samples. EGFR S492R was not detected in pre-tx samples. Results are shown (table). Conclusions: In a retrospective analysis of pts with available samples from ASPECCT, 16% of pts in the cmab arm and 1% of pts in the pmab developed EGFR S492R mutations. Pts with EGFR S492R in the cmab arm had longer tx duration before progressive disease (PD) and appeared to have worse OS vs pts with wild-type S492 in the cmab arm. Clinical trial information: NCT01001377. [Table: see text]

Amphotericin B Treatment for Indian Visceral Leishmaniasis: Conventional versus Lipid Formulations

In Bihar, India, where visceral leishmaniasis is hyperendemic, amphotericin B deoxycholate is now first-line parenteral treatment. To test the efficacy of amphotericin B deoxycholate versus that of its lipid formulations, Indian patients were randomized to receive treatment with amphotericin B deoxycholate (1 mg/kg on alternate days for 30 days; n=51), liposomal amphotericin B (2 mg/kg per day for 5 days; n=51), or amphotericin B lipid complex (2 mg/kg per day for 5 days; n=51). Infusion-associated reactions were frequent and persistent in subjects treated with amphotericin B deoxycholate. The illness of 3 patients failed to respond to treatment, and 5 patients experienced relapse. Final cure rates were similar. Estimated total treatment costs for a 25-kg patient-417 dollars for amphotericin B deoxycholate, 872 dollars for liposomal amphotericin B, and 947 dollars for amphotericin B lipid complex-differed as a result of drug cost. Substantial reductions (approximately 60%) in the price of liposomal amphotericin B and amphotericin B lipid complex would make treatment costs comparable to that of amphotericin B deoxycholate, permitting administration of short-course regimens in India.