4 daily by the parents of the subjects. At the beginning of the visit, laboratory testing was conducted and processed. The investigator performed a short physical and documented a CGI-I. Upon completion of a physical exam and receipt of laboratory results to assess conditions that may be related to drug toxicity, medication was dispensed for the next week. 2.8. Statistical Analysis. Data were graphically displayed and descriptive statistics used to assess the distribution of the measurements. The Wilcoxon signed-ranks test was used to analyze diﬀerences in the measurements between baseline, 6, and 12-week followup. The area under the curve (AUC), maximum observed concentration (Cmax) and sampling time (hour) at which Cmax occurred (tmax) were used to evaluate the results of the pharmacokinetic testing. 3. Results Seven white males aged 6–12 were enrolled in the study (Table 1). All children had parental history reporting regres- sion between 12 and 18 months with loss of eye contact, verbal ability, and loss of nonverbal gesturing in 4/7 patients. No children regressed during the course of the study. Baseline CSF TNF-α in one of the seven children was processed using 1 : 1 dilution, the rest with 1 : 10 dilutions based on laboratory recommendations (InterScience Laboratory). Three children had initial observed rote and simple 1-2 word phrased speech, mostly with prompting, while four children were nonverbal. These lower functioning children were most likely why outcomes were harder to observe for language change. Prestudy serum and CSF TNF-α values were obtained 8.5 ± 5.7 months prior to baseline repeat serum levels. One child’s initial sample was obtained 20.7 months prior to the start of the study but the repeat results were obtained within 9 months of the baseline visit. Serum TNF-α was processed with 1 : 1 dilution for two children and 1 : 10 dilution for ﬁve children. All patients had serum levels of cytokines done at baseline and one patient had CSF sample repeated. Pharmacokinetic (PK) data were obtained for 7 subjects (Table 2 and Figure 1). Six of the seven children had serum concentrations between 20 and 60 pg/mL one hour after the ﬁrst dose. Eight hours after the ﬁrst dose, the serum concentration for all children was less than 20 pg/mL. The PK value for subject 5 was signiﬁcantly higher than all other subjects at the 1-hour mark but this normalized at 2 hours. Table 2 provides the parameter estimates for each patient. Concentration peaked in the second hour for 2 subjects and in the ﬁrst hour for the remaining 5. Two patients developed a rash and were discontinued from the study. One patient was discontinued from the study after eight weeks for transient drop of absolute neutrophil count of 1200 (safety cutoﬀ 1500). All rashes cleared after stopping lenalidomide, and ANC returned to normal levels after stopping in patient aﬀected. 3.1. TNF-α. At the 12-week followup, 1 : 10 diluted serum TNF-α was obtained in three of the same children who had Autism Research and Treatment 1 : 10 diluted serum at baseline. One case processed using 1 : 1 dilution at baseline had his serum processed using 1 : 1 at the 12-week followup. One child’s serum was processed using 1 : 1 dilution at baseline and was processed using 1 : 10 dilution at follow-up; therefore, this case was excluded from the analysis (protocol change from InterScience laboratory). CSF TNF-α values were consistently measured for four subjects who completed the study (Table 1). CSF-TNF-α declined an average of 57% ± 25% from 80.5 ± 41.03 to 38.0±31.27 in four children whose samples were consistently measured and completed the study at 12 weeks (P = 0.068). Serum TNF-α showed decline of 57% (92.50 ± 68.92 to 40.25 ± 44.53; P = 0.068). Only TNF-α was used as an exploratory outcome measure because other cytokines were not always available in all patients. The investigator has also observed and reported of elevated CSF/serum ratios in autistic patients [7]. 3.2. Language and Behavioral Measures. At the 6-week followup, mean receptive language in three of the six patients with initial phrase speech increased from 60.67 ± 12.06 to 65.00 ± 15.10 (P = 0.110) (Table 3). Six children who completed the 6-week followup showed decreased symptoms of autism based on the CARS scores that was signiﬁcant for change (baseline 40.75 ± 5.96 versus 6 weeks 38.67 ± 7.90, P = 0.043). Clinical Global Impression ratings by the investigator indicated some improvements in socialization, language expression, and receptive speech (Table 4). Mean baseline CGI expressive language was 5.43 ± 1.27 and was statistically improved at 6 weeks (4.00 ± 2.12, P = 0.042) and at 12 weeks (4.17 ± 1.60, P = 0.023). CGI assessment of receptive language showed a similar improvement between baseline (4.50 ± 1.56) and 6 weeks (2.50 ± 1.18, P = 0.027) but the improvements did not remain statistically signiﬁcant at 12 weeks (3.33 ± 1.63, P = 0.066). While social skills scores improved at both 6 weeks (2.50 ± 1.00) and 12 weeks (3.00 ± 1.41), the diﬀerences were not signiﬁcant compared to baseline (4.83 ± 1.17) P = 0.066. 4. Discussion This was a pilot study to determine the safety and potential eﬃcacy of lenalidomide in a small number of patients and was not intended to have adequate power to achieve statistically signiﬁcant ﬁndings. The fact that the majority of the patients with history of regression showed almost no expressive ability at baseline is not atypical for some regressive subtypes seen clinically, but it limited the ability of the study to measure any signiﬁcant change. This study suggests that the oral TNF-α inhibiting agent lenalidomide is a potential novel mechanism for treatment of autism with regression in the presence of elevated TNF-α markers in CSF and serum. Clear clinical lowering of TNF-α in both serum and CSF was observed in four patients completing the 12-week study. These ﬁndings build upon prior animal models of inﬂammatory cytokine elevation and change in rat oﬀspring behavior with cytokine treatment [17, 18] and