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Olivera et al. Cancer Drug Resist 2019;2:53-68 I http://dx.doi.org/10.20517/cdr.2018.25 Page 57

rs80081766+ CC CT, TT + AC, AA
rs78060119
rs55886062 CC AC, AA
rs1801265 AA AG, GG
rs1801268 CC AC, AA
Irinotecan DPWG [6]
2
UGT1A1 rs8175347 (TA)6/ (TA)7/(TA)7 Dose > 250 mg/m : reduce initial dose by 30%. Increase
2
(TA)6 dose in response to neutrophil count. Dose ≤ 250 mg/m :
(TA)6/ no dose adjustment
(TA)7
Ondansetron # CPIC [21]
CYP2D6 - PM, IM, NM UM: *1/*1xN, Select alternative drug not predominantly metabolized by
*1/*2xN, *2/*2xN CYP2D6 (i.e., granisetron)
Oxycodone DPWG [6]
CYP2D6 NM PM: two inactive Select alternative drug (not tramadol or codeine) or be
alleles (*3-*8, *11- alert to insufficient efficacy
*16, *19-*21, *38,
*40, *42); IM: two
decreased-activity
alleles (*9, *10, *17,
*29, *36, *41) or
carrying one active
(*1, *2, *33, *35)
and one inactive
allele, or carrying
one decreased-
activity allele and
one inactive allele
UM: gene Select alternative drug (not tramadol or codeine) or be
duplication in alert to ADEs
absence of inactive
(*3-*8, *11-*16,
*19-*21, *38, *40,
*42) or decreased-
activity (*9, *10,
*17, *29, *36, *41)
alleles
Tamoxifen CPIC [22]
More alleles exist, these are the most common [22]
CYP2D6 - - UM: *1/*1xN, Avoid moderate and strong CYP2D6 inhibitors. Initiate
*1/*2xN, *2/*2xN therapy with recommended standard of care dosing
(tamoxifen 20 mg/day)
- - NM: *1/*1, *1/*2, Avoid moderate and strong CYP2D6 inhibitors. Initiate
*1/*9, *1/*41, therapy with recommended standard of care dosing
*2/*2 (tamoxifen 20 mg/day)
- - NM or IM Consider hormonal therapy such as an aromatase
(controversy inhibitor for postmenopausal women or aromatase
remains): *1/*4, inhibitor along with ovarian function suppression in
*1/*5, *41/*41; premenopausal women. If aromatase inhibitor use is
*4/*10, *4/*41, contraindicated, consideration should be given to use a
*5/*9; *10/*10, higher but FDA approved tamoxifen dose (40 mg/day).
*10/*41 Avoid CYP2D6 strong to weak inhibitors
- - PM: *3/*4, *4/*4, Recommend alternative hormonal therapy such as
*5/*5, *5/*6 an aromatase inhibitor for postmenopausal women
or aromatase inhibitor along with ovarian function
suppression in premenopausal women given that
these approaches are superior to tamoxifen regardless
of CYP2D6 genotype and based on knowledge that
CYP2D6 poor metabolizers switched from tamoxifen to
anastrozole do not have an increased risk of recurrence.
Note, higher dose tamoxifen (40 mg/day) increases but
does not normalize endoxifen concentrations and can be
considered if there are contraindications to aromatase
inhibitor therapy
DPWG [6]
- - PM: see Increased risk for relapse of breast cancer. Consider
description in aromatase inhibitor for postmenopausal women
oxycodone