Introduction
Palbociclib, a selective cyclin-dependent kinase (CDK) 4/6 inhibitor, is currently
under investigation for the treatment of multiple cancers. Here we describe a patient
with metastatic breast cancer who had a Stevens-Johnson syndrome (SJS)-like reaction
with a protracted course after 3 weeks of therapy with palbociclib. The patient's
lesions improved with cessation of palbociclib and treatment with oral cyclosporine.
This is the first report to our knowledge of a CDK 4/6 inhibitor associated with a
severe cutaneous reaction.
Case presentation
A 63-year old woman with a history of metastatic breast cancer presented to the emergency
room with a 3-week history of a worsening, painful rash that started on her face and
spread to her trunk and extremities after 6 weeks of treatment with palbociclib and
fulvestrant. She had last taken palbociclib 5 days and fulvestrant 1 week before her
presentation. Associated symptoms included malaise, dysuria, and a gritty sensation
in her eyes. She denied any other new medications.
This patient's medical history was notable for psoriatic arthritis. Her breast cancer
was diagnosed 5 years ago and treated with lumpectomy, cyclophosphamide, and docetaxel
followed by adjuvant aromatase inhibitor therapy. At the time of metastatic recurrence,
the patient received fulvestrant for 2 years. Most recently, 1 year prior, she was
placed on a clinical trial of entinostat or placebo plus an aromatase inhibitor. Because
of progression, the patient was switched to palbociclib and fulvestrant therapy. She
did not experience any dermatologic complications with prior therapies.
Physical examination found pink-to-violaceous, eroded, tender plaques with collarettes
of scale on the face, trunk, and legs, some of which had yellow crust and dusky centers
(Fig 1). Hemorrhagic crust was noted around the patient's lips (Fig 1, A). The oropharynx
was spared. Nikolsky sign was initially negative but became positive the following
day.
Fig 1
Clinical images. A, Pink to violaceous, eroded plaques with collarettes of scale and
dusky centers on the face. Hemorrhagic crust around the lips. B, Similar lesions on
the back.
Skin biopsy found vacuolar interface dermatitis, focal full-thickness epidermal necrosis,
and mild superficial perivascular lymphocytic infiltrate with pigment incontinence
and dermal edema (Fig 2). Immunofluorescence studies did not find any immunoreactants.
Fig 2
Histology. A, Biopsy of left upper back shows vacuolar interface dermatitis with focal
full thickness epidermal necrosis and mild superficial perivascular lymphocytic infiltrate
and dermal edema. B, Detail shows vacuolar interface and focal full thickness epidermal
necrosis. A and B, Hematoxylin-eosin stain; original magnifications: A, ×40; B, ×200.)
The painful skin, ocular symptoms, mucocutaneous erosions, positive Nikolsky sign,
and full-thickness epidermal necrosis seen on biopsy supported the diagnosis of SJS.
Paraneoplastic pemphigus was considered but excluded given the lack of immunoreactants.
The most likely cause of this patient's SJS was thought to be palbociclib. The patient
had previously tolerated fulvestrant for 2 years without adverse effects. Herpes simplex
virus IgM was negative, and there was no suggestion of Mycoplasma infection based
on symptomatology. Oral cyclosporine at 5 mg/kg was started and slowed the progression
of her lesions. The ophthalmology and gynecology departments were consulted because
of concern for mucous membrane involvement; ultimately none was found.
After 1 week of initial cyclosporine therapy, her dose was halved to 2.5 mg/kg for
another 2 weeks given continued formation of new bullae. At a 1-month follow-up appointment,
her initial SJS-like eruption had resolved but had been replaced with a psoriasiform
dermatitis.
Discussion
SJS and toxic epidermal necrolysis (TEN) are life-threatening cutaneous reactions
characterized by necrosis of the epidermis. In adults, most cases are caused by drug
hypersensitivity.
1
SJS/TEN is thought to be mediated by T cells activated by drug-related haptens or
direct noncovalent interaction of the drug itself with major histocompatibility complex
I or T-cell receptor.
1
Onset of the patient's symptoms 3 weeks after palbociclib is consistent with the time
course of SJS.
2
The continued progression of her symptoms was likely caused by continued ingestion
of the inciting medication. However, after discontinuation of the likely trigger,
her eruption continued for more than 4 weeks, suggesting an SJS-like reaction with
a more protracted course. The development of a psoriasiform dermatitis in areas of
the resolving eruption could represent Koebner phenomenon given the patient's history
of psoriatic arthritis.
We cannot completely exclude other potential causes of SJS. She had tolerated her
other medications, including fulvestrant, for years without cutaneous adverse effects.
Using the algorithm for drug causality for epidermal necrolysis developed by Sassolas
et al,
3
the score for palbociclib was 3, suggesting possible cause, and 1 for fulvestrant,
suggesting unlikely cause.
3
Palbociclib and other CDK 4/6 inhibitors, including ribociclib and abemaciclib, are
being studied in several clinical trials for the treatment of a variety of malignancies,
and all have approvals in breast cancer.
4
In 2013, the US Food and Drug Administration granted palbociclib breakthrough therapy
designation in combination with an aromatase inhibitor as initial therapy for hormone
receptor (HR)+, human epidermal growth factor receptor 2 (HER2)− metastatic breast
cancer for postmenopausal women. Palbociclib received accelerated approval in 2015
on the basis of a phase 3 confirmatory trial, PALOMA-2 (NCT01942135), that found improved
progression-free survival (24.8 vs 14.5 months) in patients treated with palbociclib
or placebo and letrozole.
5
Two other CDK 4/6 inhibitors, ribociclib and abemaciclib, have also been approved
for HR+/HER2
- metastatic breast cancer.6, 7
CDK 4/6 inhibitors are well tolerated. In the phase 3 PALOMA-3 trial of palbociclib
and fulvestrant for breast cancer, the most common severe adverse effects in the palbociclib-treated
group were neutropenia and leukopenia, occurring in 27% and 55% of participants, respectively.
8
Grade 3 rash (severe reaction, requiring hospitalization and limitation of activities)
occurred in 1% of the participants receiving palbociclib plus fulvestrant, but grade
1 to 2 rash occurred in 14% of participants. No grade 4 or higher rashes (life-threatening
reaction requiring urgent intervention) were reported.
8
Thus far, ribociclib and abemaciclib have not been reported to be associated with
SJS/TEN. Ribociclib is associated with transaminitis and QTc prolongation, and abemaciclib
is associated with more fatigue and gastrointestinal-related toxicity compared with
palbociclib.6, 7
Given the severity of the patient's presentation, palbociclib and fulvestrant were
discontinued. Several alternative cancer therapy options are available including everolimus
plus exemestane,
9
tamoxifen, chemotherapy, and clinical trial therapies.
As palbociclib in combination with an aromatase inhibitor is approved for first-line
endocrine-based therapy for postmenopausal women with HR+/HER2
− advanced breast cancer, many patients are likely to come into contact with this
drug.5, 10 Our observations suggest palbociclib may potentially elicit an SJS-like
reaction. We report this case to raise awareness about the possible risk of palbociclib-induced
SJS and the need for close monitoring for signs of a cutaneous drug reaction after
initiation of this medication.