Baseline mutational profiles of patients with carcinoma of unknown primary origin enrolled in the CUPISCO study

BACKGROUND

Patients with unfavorable carcinoma of unknown primary origin (CUP) have an extremely poor prognosis of ∼1 year or less, stressing the need for more tailored treatments, which are currently being tested in clinical trials. CUPISCO (NCT03498521) was a phase II randomized study of targeted therapy/cancer immunotherapy versus platinum-based chemotherapy in patients with previously untreated, unfavorable CUP, defined as per the European Society for Medical Oncology guidelines. We present a preliminary, descriptive molecular analysis of 464 patients with stringently diagnosed, unfavorable CUP enrolled in the CUPISCO study.

MATERIALS AND METHODS

Genomic profiling was carried out on formalin-fixed, paraffin-embedded tissue to detect genomic alterations and assess tumor mutational burden and microsatellite instability.

RESULTS

Overall, ∼32% of patients carried a potentially targetable genomic alteration, including PIK3CA, FGFR2, ERBB2, BRAFV600E, EGFR, MET, NTRK1, ROS1, and ALK. Using hierarchical clustering of co-mutational profiles, 10 clusters were identified with specific genomic alteration co-occurrences, with some mirroring defined tumor entities.

CONCLUSIONS

Results reveal the molecular heterogeneity of patients with unfavorable CUP and suggest that genomic profiling may be used as part of informed decision-making to identify the potential primary tumor and targeted treatment options. Whether stringently diagnosed patients with unfavorable CUP benefit from targeted therapies in a similar manner to those with matched known primaries will be a key learning from CUPISCO.

Multicentric neoadjuvant phase II study of panitumumab combined with an anthracycline/taxane-based chemotherapy in operable triple-negative breast cancer: identification of biologically defined signatures predicting treatment impact

BACKGROUND

Triple-negative breast cancer (TNBC) is a heterogeneous group of tumors for some of which the epithelial growth factor receptor (EGFR) pathway may play an important role. We investigated the efficacy and toxicity of an anti-EGFR antibody (panitumumab) combined with a standard neoadjuvant anthracycline-taxane-based chemotherapy in patients with operable, stage II-III, TNBC.

PATIENTS AND METHODS

Treatment in this multicentric neoadjuvant pilot study consisted of panitumumab (9 mg/kg) for eight cycles q.3 weeks combined with four cycles of 5-fluorouracil, epidoxorubicin and cyclophosphamide (FEC100: 500/100/500 mg/m(2)) q.3 weeks, followed by four cycles of docetaxel (T: 100 mg/m(2)) q.3 weeks. Following therapy, all patients underwent surgical resection. Pathologic complete response (pCR) in assessable patients was the main end point while clinical response, toxicity and ancillary studies were secondary end points. Paraffin-embedded and frozen tumor samples were systematically collected with the aim to identify predictive biomarkers of efficacy and resistance in order to select biologically defined subpopulations for potential further clinical development of the anti-EGFR antibody.

RESULTS

Sixty patients were included with 47 assessable for pathologic response. The pCR rates were 46.8% [95% confidence interval (CI): 32.5% to 61.1%] and 55.3% [95% CI: 41.1% to 69.5%] according, respectively, to Chevallier and Sataloff classifications. The complete clinical response (cCR) rate was 37.5%. Conservative surgery was carried out in 87% of cases. Toxicity was manageable. The association of high EGFR and low cytokeratin 8/18 expression in tumor cells on one hand and high density of CD8+ tumor-infiltrating lymphocytes on the other hand were significantly predictive of pCR.

CONCLUSIONS

Panitumumab in combination with FEC100 followed by docetaxel appears efficacious, with acceptable toxicity, as neoadjuvant therapy of operable TNBC. Several biomarkers could help define large subsets of patients with a high probability of pCR, suggesting a potential interest to further develop this combination in biologically defined subgroups of patients with TNBC.

CLINICAL TRIAL NUMBER

NCT00933517.

Abstract P5-08-07: HER3, MET and immune pathways play important roles in the resistance of triple negative breast cancer (TNBC) after neoadjuvant anti-EGFR (panitumumab) combined with FEC 100

Background: Our group has previously reported (SABCS 2012, abstract 1081) a 2-fold higher pathologic complete response (pCR) rate in TNBC treated with panitumumab+FEC100 (47%) than with the standard therapy alone. However, in a half of the patients (pts) a residual tumor (RT) was detected. Having in mind the detrimental impact of resistant TNBC on patient outcome, we have investigated the tumor tissue factors that might have been important in development of resistance to this treatment.

Methods: 40 TNBC pts, treated with 8 cycles the anti-EGFR antibody panitumumab combined with FEC 100 for the first 4 and with docetaxel only for the last 4 cycles, were eligible. All pts underwent breast surgery after the neoadjuvant chemotherapy (NACT) completion. Formalin-fixed, paraffin-embedded tumor samples were collected before and after NACT for biomarker analysis. EGFR, HER3, IGF-1R, MET and the number of FOXP3+ or CD8+ tumor-infiltrating lymphocytes (TIL) were evaluated by immunohistochemistry (IHC). Expression of the kinases was graded semi-quantitatively (histoscores).

Results: Out of 40 treated pts, 21 demonstrated a RT (53%, according to the Chevallier classification, PMID 8338056). The IHC data were available for 17 pts. Since high EGFR expression was important for pCR achievement in this study (SABC 2012), we first investigated the expressions of EGFR, HER3 and MET in the RT. The results are presented in Table 1.

Table 1post-NACT RTn = 17EGFR down or flatEGFR up143HER3 upHER3 flatHER3 upHER3 flat8512MET upMET down or flatMET upMET down or flatMET upMET down or flatMET upMET down or flat17220120

Overall, among the 9 cases (cs) with increased post-NACT HER3 expression (HER3 up), only 1 had increased MET (MET up), while among the 7 cs with no change in HER3 post-CTNA (HER3 flat), 4 had MET expression increased.

Interestingly, although the pre-NACT IGF-1R expression was a strong predictor of pCR (p = 0.028, SABCS 2012), no significant changes in this kinase expression were observed in the RT, compared to the pre-NACT levels. Most RT had low IGF-1R scores (<100). The only 2 RT in which IGF-1R was increased post-CTNA were small groups of tumor cells either in breast or in the nodes, heavily surrounded by lymphocytes.

The density of TIL post-NACT correlated principally with the% of tumor mass (TM) reduction. Among the 7 pts with average reduction of 20%, there was only 1 cs with a good InSitu Immune Response (ISIR: dense TIL, with CD8+/FOXP3+ > 1.2). On the contrary, among the 9 pts with average TM reduction of 90%, 8 demonstrated a good ISIR.

Conclusion: The results indicate that HER3 and MET play significant roles in development of TNBC resistance to the anti-EGFR agents. Those molecules seem to drive 2 different resistance pathways in TNBC, as it has been shown in other malignancies. As several anti-HER3 or anti-MET drugs are nowadays available, we find very important investigating the expression of HER3 and MET in each TNBC pt pre- and post-NACT, in order to rapidly detect and combat the resistance. The ISIR-stimulating agents may bring an additional therapeutic benefit to those patients.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-08-07.

Abstract P1-08-34: Is it possible to predict the efficacy of a combination of cetuximab plus docetaxel in patients with operable, triple negative breast cancer (TNBC)? Final biomarker results from a phase II neoadjuvant trial

Background: TNBC is a heterogenous group of tumors for some of which the Epithelial Growth Factor Receptor pathway (EGFR) may play an important role. We evaluated the efficacy and toxicity of an anti-EGFR antibody (cetuximab) combined with docetaxel, which were given to the TNBC patients (pts) in the neoadjuvant setting. A biomarker analysis accompanied this trial, aiming to identify predictors of response.

Methods: 35 patients with stage II-IIIA TN breast disease were prospectively included in this multicentre pilot study. Systemic therapy (ST) consisted of 6 cycles of docetaxel (100 mg/m2) each 3 weeks, in combination with weekly cetuximab (first dose 400mg/m2 then 250 mg/m2/week) for 6 cycles. All patients underwent surgery at completion of ST.

Patient characteristics : mean age 48 [28-67]; TNM: T1: 3%, T2: 73%, T3: 24%; N0: 61%, N1-N2: 39%; mean tumor size 40 mm [15-100]; SBR: grade III: 73%, grade II: 27%. The median number of cycles was for docetaxel 6 [1-6] and for cetuximab 15 [1-18]. Pathological complete response (pCR) rate was 24% according to the Chevallier and Sataloff classifications; 28% if we consider breast pCR only. Overall clinical response rate was 57% (22% CR). Conservative surgery was performed in 75% of cases. The main side effect was skin toxicity: grade II: 39%, grade III: 36%, grade IV: 3%. Other side effects were: neutropenia grade IV: 12.7%, febrile neutropenia: 1.3%, hand-foot syndrome grade III: 3%, grade II: 3%, ungueal toxicity grade III: 3%, grade II: 33%.

Paraffin-embedded and frozen samples were systematically collected before and after ST for biomarker studies. Germinal BRCA1 mutations and EGFR, KRAS, BRAF and PI3KCA somatic mutations were analyzed by NGS. EGFR, MET, cytokeratins 5/6 and 8/18, PTEN, P-cadherin, ALDH1, Ki67, p53 and the number of FOXP3+ or CD8+ tumor-infiltrating lymphocytes (TIL) were evaluated by immunohistochemistry.

Results: The biomarker analysis was interpretable on the samples from 21 pts (3 pCR and 18 non-pCR).

We applied the ROC curve to identify the best cut-off value for Ki67, EGFR, MET, cytokeratin 5/6 and 8/18, p53, ALDH1, PTEN, P-cadherin and the FOXP3+ or CD8+ TIL counts. None of these biomarkers was predictive of pCR except for the CD8+/FOXP3+ TIL count ratio. pCR rate was higher in the pts with the ratio equal or higher than 2.75 than in the others (43% versus 0%, p = 0.047).

BRCA1 mutations were detected in 16% of pts. PI3K and EGFR somatic mutations were observed in 1 and 3 patients, respectively. The presence of the mutations was not predictive of pCR.

Conclusion: Similarly to the previously reported trial by our group (SABCS 2012, abstract 1081), the immune component of the tumor microenvironment plays a very important role in the TNBC response to cytotoxic therapy.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-08-34.

Abstract P3-14-19: Panitumumab in combination with FEC 100 (5-fluorouracil, epirubicin, cyclophosphamide) followed by docetaxel for operable, triple negative breast cancer (TNBC): Patient outcome

Background: Panitumumab is an antibody targeting the epidermal growth factor receptor (EGFR) for which an important role has been suggested in TNBC. Consequently, we evaluated a combination of the standard chemotherapy (FEC 100 followed by docetaxel) with panitumumab as neoadjuvant therapy of operable TNBC. Complete pathologic response (pCR) was the primary endpoint, with clinical response, toxicity, and outcome as secondary endpoints. An investigation of biomarkers possibly predictive of pCR accompanied this trial. Here we focus on tumor recurrence, after a median follow up of 33 months [25-40] as on April, 1, 2013.

Methods: Sixty patients (pts) with stage II-IIIA TNBC were prospectively included. Systemic neoadjuvant treatment (ST) consisted of the anti-EGFR antibody panitumumab combined with FEC 100, followed by 4 cycles of docetaxel. All pts underwent surgery after ST completion. Patient characteristics: median tumor size: 40 mm [20-120]; SBR grade III: 71.7%; pCR rate: 55.3% and 46.8% (the Sataloff and the Chevallier classifications, respectively). Paraffin-embedded and frozen tumor samples were collected before and after ST for biomarker analysis. EGFR, IGF-1R, MET, cytokeratins 5/6 and 8/18, PTEN, P-cadherin, ALDH1, Ki-67, p53, tumoral FOXP3 expression and the number of FOXP3+ or CD8+ tumor-infiltrating lymphocytes (TIL) were evaluated by immunohistochemistry.

Results :.We have observed 9 recurrences: 1 local and 8 distant recidives, including 1 both local and distant.

The distant recidives (metastases) were as follows: brain (4 pts); brain and lungs (1 pt); lungs only (1 pt), pleura (1 pt); liver (1 pt). 6 out of the 8 metastatic pts died and all were non-pCR post-ST. The 2 alive pts had brain metastases, but reached a pCR after the ST.

Among the 9 relapsed pts 6 were 55 years old or less at the diagnosis. Seven out of those 9 pts had tumors with the clinical size equal or higher than 4 cm.

As previously reported (SABCS 2012, abstract 1081), the pCR-predictive biomarkers in this study were high CD8+ TIL count (p = 3.4.10−6) and high ratio between the CD8+ and FOXP3+ TIL counts (CD8+/FOXP3+ > 1.23, p = 8.5.10−5). With this in mind, we have evaluated whether those parameters, assessed before or after the ST, could predict the recurrences. No difference was found in the preoperative CD8+ and the FOXP3+ TIL counts, as well as in the CD8+/FOXP3+ ratio, between the patiens who have recurred and the others.

Conclusion : As it has been reported in previous studies, in our cohort of TNBC pts, the relapses occurred early after the administration of the last systemic treatment. The patients who relapsed died rapidly and most of them have not reached pCR after the ST. In addition, half of the metastatic pts got brain deposits. This implies that research on the resistance factors in TNBC should focus on those important for seeding of the “sanctuaries”, like brain. This research is ongoing in our group.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-14-19.

Abstract P3-06-20: Is it possible to predict the efficacy of a combination of Panitumumab plus FEC 100 followed by docetaxel (T) for patients with triple negative breast cancer (TNBC)? Final biomarker results from a phase II neoadjuvant trial

Background: TNBC is an heterogeneous group of tumors for some of which the Epithelial Growth Factor Receptor pathway (EGFR) may play an important role. We evaluated the efficacy and toxicity of an anti-EGFR antibody (panitumumab) combined with a standard neoadjuvant chemotherapy in order to identify predictive biomarkers of efficacy and target biologically defined subpopulations for potential further development.

Methods: Sixty patients with stage II-IIIA disease were prospectively included in this multicentre neoadjuvant study. Systemic therapy (ST) consisted of panitumumab (9 mg/kg q.3 weeks x8) combined with FEC 100 (500/100/500 mg/m2q.3 weeks x4) followed by 4 cycles of T (100 mg/m2 q.3weeks x4). All patients underwent surgery at completion of ST.

Paraffin-embedded and frozen samples were systematically collected before and after ST for biologic studies.

Patients characteristics are as follows: mean age 50 [27–72]; median tumor size: 40 mm [20–120]; invasive ductal carcinoma: 96.7%; Scarff-Bloom-Richardson Grade III: 71.7%, grade II: 28.3%.

Complete pathological response (pCR) rate was 52.3% [95% IC: 37.3–67.5] (Sataloff's classification) and 46.7% [95% IC: 31.6–61.4](Chevallier's classification). Conservative surgery was performed in 88% of cases.

Skin toxicity was the main side-effect: Cutaneous toxicity grade IV: 5%, grade III: 30%, grade II: 20%. Neutropenia grade IV: 27%; febrile neutropenia: 5%. Infection: 0%. Hand-foot syndrome grade III: 3.3%. Ungueal toxicity grade III: 1.6%, grade II: 20%.

Results: We performed a ROC curve to identify the best cut-off value for KI-67, EGFR, cytokeratin 5–6 and p53 in order to predict a pCR.

Tumors with more than 40% of positive cells for KI-67 and tumors with a score for EGFR greater than 70 tend to be associated with pCR according to Chevallier's classification (p = 0.06). No predictive value was identified for Cytokeratin 5–6 and p53 (p = 0.61 and p = 0.27, respectively).

Immunohistochemistry results show that two thirds of tumors have more than 40% of positive cells for KI-67 and that two thirds of tumors present a score for EGFR greater than 70.

About half of the tumors express cytokeratin 5–6 and p53 (cut off: 1%).

Chi-squared tests were performed to assess relations between cutaneous toxicities and pCR.

The cutaneous toxicities were not predictive of pCR (p = 0.94) and no correlations were found with KI-67, EGFR, Cytokeratin 5–6 and p53.

In terms of BRCA1 and BRCA2 status, 35 tumors were analysed so far: BRCA1: 6 mutations (17%); BRCA2 (30 patients): 1 mutation (3.3%).

Conclusions: These results suggest the possibility to identify a subpopulation with high probability of pCR (KI-67 > 40%, EGFR score > 70).

Further biological studies are ongoing and will be presented at the meeting, including EGFR polymorphisms, C-met, ALDH1, pCadherine and PTEN.

This will help us further define subpopulations of TNBC patients, potential targets for antiEGFR development.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P3-06-20.

Comparative clinical and transcriptomal profiles of breast cancer between French and South Mediterranean patients show minor but significative biological differences

BACKGROUND

In Western countries, breast cancer incidence and mortality are higher than in Mediterranean countries. These differences have been ascribed to environmental factors but also to late-stage diagnostic and biological specific characteristics.

PATIENTS AND METHODS

Between September 2002 and September 2005, we collected clinical data by phone counselling 180 French and Mediterranean breast cancer patients and performed microarray experiments.

RESULTS

Characteristics of breast cancer in patients from Lebanon, Tunisia and Morocco were more aggressive (more SBR grade III and positive node invasion) and patients were 10 years younger at diagnosis. Sixteen differentially expressed genes such as MMP9, VEGF, PHB1, BRCA1, TFAP2C, GJA1 and TFF1 were also found. Additionally, an up-regulation of cytokeratins KRT8 and KRT18 may indicate a luminal B subtype in "South" (Lebanon, Tunisia and Morocco) tumors while "North" (France) tumors may more frequently be luminal A type.

CONCLUSION

This study allowed the identification of specific clinical and transcriptomic parameters in patients from South Mediterranean countries.

Quantification by affinity perfusion chromatography of phosphorylated BRCAl and BRCA2 proteins from tumor cells after lycopene treatment

A new procedure for the quantification of phosphorylated BRCA1 (P-BRCA1) and BRCA2 (P-BRCA2) proteins in breast cell lines after different treatments was carried out. Cells were cultivated with [35S]-methionine and extracts subjected to three perfusion chromatographies. First heparin affinity chromatography purified cellular DNA-binding proteins. Subsequent specific immunoprecipitation of BRCA1 and BRCA2 proteins was performed with antibodies raised against BRCA1 or BRCA2. The immune complexes were isolated by protein A affinity chromatography. Phosphorylated BRCA1 or BRCA2 proteins were then purified with a Poros 20 AL column where anti-phosphothreonine and anti-phosphoserine antibodies were previously bound. The percentage of phosphorylated BRCA1 or BRCA2 proteins was calculated as follows: 100 x dpm of P-BRCA1 or P-BRCA2 eluted from the POROS 20AL column/total dpm eluted from POROS 20AL column. Treatment with 10 microM lycopene increased P-BRCA1 and P-BRCA2 in the breast tumor cell line MCF7 but not in MDA-MB-231 or MCF-10a, breast tumor or fibrocystic cell lines, respectively.

Resveratrol and breast cancer chemoprevention: molecular mechanisms

Despite years of intensive research, breast cancer remains a major cause of death among women. New strategies to combat breast cancer are being developed, one of the most exciting of which is the use of chemopreventive agents. Resveratrol (RES) is a polyphenolic compound found in plants that seems to have a wide spectrum of biological activity. RES has been shown to afford protection against several types of cancer. This review summarizes the chemopreventive effects of RES at the three major stages of breast carcinogenesis: initiation, promotion, and progression. It has anti-oxidant and anti-inflammatory properties, and may induce apoptosis as well as modulate cell cycle and estrogen receptor function in breast cancer cell lines. Although RES has shown remarkable promise as a potent chemopreventive agent in breast cancer, further studies are needed to etablish its usefulness.

Quantitative analysis of BRCA1, BRCA2 and Hmsh2 mRNA expression in colorectal Lieberkühnien adenocarcinomas and matched normal mucosa: relationship with cellular proliferation

The human DNA mismatch repair gene hMSH2 is involved in the development of sporadic and hereditary nonpolyposis colorectal cancer. An increased risk of colorectal cancer has also been suggested in BRCA1 and BRCA2 mutation carriers. To address the relationship between the expression level of these genes and colorectal tumorigenesis, we studied BRCA1, BRCA2 and hMSH2 mRNA expression by real-time quantitative RT-PCR in 72 colorectal Lieberkühnien adenocarcinomas and matched normal mucosa. We investigated the relationship between mRNA levels and various clinicopathological parameters. The mean expression of BRCA1 3' and BRCA2 3' (mRNA pool), BRCA1 ex11 (with exon 11), BRCA2 ex12 (with exon 12) and hMSH2 mRNAs were increased in tumor samples. BRCA1 and BRCA2 mRNAs expressions were altered according to colon tumor site: BRCA1 3' and BRCA2 3' mRNAs levels were highest, respectively, in the right colon and left colon. No difference in hMSH2 mRNA levels was detected in relation to clinicopathological parameters. The mean SPF value was significantly higher in tumor than in non-tumor colonic tissue, and a high SPF value was correlated with high BRCA2 mRNA levels. BRCA2 3' mRNA levels tended to decrease as the Dukes' stage increased. In conclusion, the mechanisms of colorectal carcinogenesis seem to differ according to the right or left position of the tumor.

The effects of lycopene on the proliferation of human breast cells and BRCA1 and BRCA2 gene expression

The purpose of this study was to demonstrate the effects of lycopene, the major tomato carotenoid, on the expression of the BRCA1 and BRCA2 genes in three breast tumour cell lines, MCF-7, HBL-100, MDA-MB-231 and the fibrocystic breast cell line MCF-10a. Flow cytometry analysis showed a G(1)/S phase cell cycle-arrest after treatment of the cells with 10 microM lycopene for 48 h. mRNA expression was studied by quantitative reverse transcription-polymerase chain reaction using the Taqman method. We observed an increase of BRCA1 and BRCA2 mRNA in the oestrogen receptor (ER)-positive cell lines (MCF-7 and HBL-100), and a decrease (MDA-MB-231) or no change (MCF-10a) in the ER-negative cell lines. BRCA1 and BRCA2 proteins were quantified by perfusion affinity chromatography. No variation in their expression was observed. These preliminary results on the effects of lycopene on the expression of BRCA1 and BRCA2 oncosuppressor genes in breast cancer may reflect cross-talk between the oestrogen and retinoic acid receptor (RAR) pathways.

Resveratrol increases BRCA1 and BRCA2 mRNA expression in breast tumour cell lines

The phytochemical resveratrol, found in grapes, berries and peanuts, has been found to possess cancer chemopreventive effects by inhibiting diverse cellular events associated with tumour initiation, promotion and progression. Resveratrol is also a phyto-oestrogen, binds to and activates oestrogen receptors that regulate the transcription of oestrogen-responsive target genes such as the breast cancer susceptibility genes BRCA1 and BRCA2. We investigated the effects of resveratrol on BRCA1 and BRCA2 expression in human breast cancer cell lines (MCF7, HBL 100 and MDA-MB 231) using quantitative real-time RT-PCR, and by perfusion chromatography of the proteins. All cell lines were treated with 30 microM resveratrol. The expressions of BRCA1 and BRCA2 mRNAs were increased although no change in the expression of the proteins were found. These data indicate that resveratrol at 30 micro M can increase expression of genes involved in the aggressiveness of human breast tumour cell lines.

The immunomodulatory potency of cimetidine in healthy volunteers

The effect of cimetidine, a histamine H2 receptor antagonist, was investigated in 12 healthy volunteers over a period of six weeks. Cimetidine was administered orally in a daily doses of 1,600 mg during the first three weeks of evaluation. Significant alterations in values of immunoglobulins (IgG, IgA), complement (C3), B-lymphocytes and T-helper cell counts were found after cimetidine intake. The in vitro lymphocyte proliferation response to plant mitogens was increased. In contrast to results obtained from a previous study with healthy volunteers who were given 800 mg cimetidine, we found no significant increase in the CD4/CD8 ratio and no decrease in the CD8 but a significant increase in the CD4 cell count. Whereas the peripheral blood immune system showed signs of immune system activation following 800 and 1,600 mg cimetidine intake, reactivity patterns of skin immune system, however, differed in both studies. The data suggests that cimetidine has a dose and time dependent effect on the immune system.

Immunomodulatory properties of cimetidine in ARC patients

The immunomodulatory potency of cimetidine, a histamine H2 receptor antagonist, was investigated in 33 AIDS-related complex (ARC) patients performing detailed immunological and clinical evaluations. Cimetidine was administered orally in daily doses of 1200 mg for a period of 5 months with an interruption of therapy after the first 3 months for an interval of 3 weeks. Significant (P less than 0.05) elevations of immunoglobulins (IgG, IgA), complement C4, B-lymphocytes, and OKT4+ (helper/inducer) cells were found after cimetidine intake. The in vitro lymphocyte proliferative response to plant mitogens was significantly increased, and the in vivo cell-mediated hypersensitivity reaction assessed by intradermal application of seven recall antigens improved significantly. These effects were both reversible with the discontinuation of cimetidine and reproducible with repeated administration of the drug. Clinical data such as performance status, body weight, and fever were influenced favorably (P less than 0.05) by cimetidine. The frequency of diarrhea and the lymph node size were also diminished significantly. The data suggest that cimetidine may at least partially restore immunofunctions in AIDS-related complex.