Table 1.

Clinical Characteristics of Sulfasalazine Hypersensitive Patients

	Gender	Age	Immunotherapy Indication	Previous Immunotherapy	Immunotherapy at Time of Reaction	Indication for Sulfasalazine	Duration on Sulfasalazine (days)	Clinical Presentation of Sulfasalazine Reaction	Ameliorative Measures	LTT Result	Drug Specific T Cells
Patient 1	Male	57	Metastatic melanoma	Ipilimumab. (stopped due to hypophysitis and disease progression)	Pembrolizumab	Monoarthritis (subsequently symmetrical oligoarthritis of knees and ankles)	10	Fever, erythematous maculopapular rash across face, neck, chest, and back, acute rise in ALT and CRP and lymphopenia	Discontinuation of pembrolizumab and sulfasalazine, IV methylprednisolone (3 days) followed by oral prednisolone wean	SPHA (SI 2.8, 40 µM)	SPHA, possible SP
Patient 2	Male	51	Metastatic melanoma	Ipilimumab. (stopped due to hypophysitis and hepatitis)	Pembrolizumab	Monoarthritis (subsequently symmetrical oligoarthritis of knees and ankles)	(A) 5, (B) 11, (C) 9, (D) 21—concomitant steroid	(A) Fever, cough, raised CRP. (B) Fever, raised CRP. (C) Fever, nonproductive cough, raised CRP. (D) nausea, diarrhea, raised ALT and CRP	Discontinuation/deferral of pembrolizumab and discontinuation of sulfasalazine, oral prednisolone	SP (SI 15.2, 200 µM) and SPHA (SI 3.2, 50 µM)	SPHA and SP
Patient 3	Male	77	Metastatic melanoma	Ipilimumab. (stopped due to progression)	Pembrolizumab	Symmetrical polyarthritis	35	Acute late onset colitis	Discontinuation of pembrolizumab and sulfasalazine, high dose steroids	Possible SLZ (SI 2.1, 200 µM)	SPHA and SP

Abbreviations: CRP, C-reactive protein; ALT, alanine aminotransferase; SLZ, sulfasalazine; SP, sulfapyridine; SPHA, sulfapyridine hydroxylamine; LTT, lymphocyte transformation test; SI, stimulation index.