Degenerative joint disease in the temporomandibular joint with fibrous ankylosis in a rhesus macaque (Macaca mulatta)

Background

Ankylosis in the temporomandibular joint (TMJ) is known to have various etiologies in veterinary medicine. We observed a case of fibrous ankylosis of the TMJ in a newly imported rhesus monkey (Macaca mulatta).

Case presentation

Moderate to severe attrition was found in the middle labial portion of the left maxillary canine. No tenderness around the jaw was detected in the physical examination. The WBC count, CRP level, rheumatoid factor level, and other parameters were normal. Irregularity in the joint surface was observed in both TMJs in the radiographic and computed tomographic examinations, but the left TMJ presented more severe irregularity. It was determined that the removal of the locked portion of the left canine would alleviate the case of lockjaw and allow intubation with an endotracheal tube. Canine tooth crown reduction was performed for both canine teeth. The mouth opening distance slightly (approximately 5 mm) increased up to 20 mm. We concluded that the attrition of canine teeth was not the reason for lockjaw and ankyloses originating from TMJ disease. Fibrotic synovial tissue and joint surface irregularity were observed by necropsy. The presence of fibrocartilage in most areas of the TMJ was confirmed by histology. The diagnosis was fibrous ankylosis of the TMJ associated with DJD.

Conclusions

To the best of our knowledge, this is the first report of degenerative joint disease of the TMJ in a rhesus monkey with fibrous ankylosis of the TMJ.

Differential protein stability and clinical responses of EML4-ALK fusion variants to various ALK inhibitors in advanced ALK-rearranged non-small cell lung cancer

Background

Anaplastic lymphoma kinase (ALK) inhibition using crizotinib has become the standard of care in advanced ALK-rearranged non-small cell lung cancer (NSCLC), but the treatment outcomes and duration of response vary widely. Echinoderm microtubule-associated protein-like 4 (EML4)-ALK is the most common translocation, and the fusion variants show different sensitivity to crizotinib in vitro. However, there are only limited data on the specific EML4-ALK variants and clinical responses of patients to various ALK inhibitors.

Patients and methods

By multiplex reverse-transcriptase PCR, which detects 12 variants of known EML4-ALK rearrangements, we retrospectively determined ALK fusion variants in 54 advanced ALK rearrangement-positive NSCLCs. We subdivided the patients into two groups (variants 1/2/others and variants 3a/b) by protein stability and evaluated correlations of the variant status with clinical responses to crizotinib, alectinib, or ceritinib. Moreover, we established the EML4-ALK variant-expressing system and analyzed patterns of sensitivity of the variants to ALK inhibitors.

Results

Of the 54 tumors analyzed, EML4-ALK variants 3a/b (44.4%) was the most common type, followed by variants 1 (33.3%) and 2 (11.1%). The 2-year progression-free survival (PFS) rate was 76.0% [95% confidence interval (CI) 56.8-100] in group EML4-ALK variants 1/2/others versus 26.4% (95% CI 10.5-66.6) in group variants 3a/b (P = 0.034) among crizotinib-treated patients. Meanwhile, the 2-year PFS rate was 69.0% (95% CI 49.9-95.4) in group variants 1/2/others versus 32.7% (95% CI 15.6-68.4) in group variants 3a/b (P = 0.108) among all crizotinib-, alectinib-, and ceritinib-treated patients. Variant 3a- or 5a-harboring cells were resistant to ALK inhibitors with >10-fold higher half maximal inhibitory concentration in vitro.

Conclusion

Our findings show that group EML4-ALK variants 3a/b may be a major source of ALK inhibitor resistance in the clinic. The variant-specific genotype of the EML4-ALK fusion allows for more precise stratification of patients with advanced NSCLC.